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Laxmi Institute of Technology, Sarigam
DEPARTMENT OF MECHANICAL ENGINEERING
STUDENT REFERENCE MANUAL B.E COURSE
SEMESTER- VI (Jan-June 2016)
Address: Post Bag No. 15, Shrigam P. O Valsad, Gujarat 0260 278 6661 Website:www.litsarigam.co.in
Laxmi Institute of Technology, Sarigam (Electronics And Communication Engineering Department)
Vision Laxmi Institute of technology endowed with awareness on abundance of human resources particularly concentrated in the band of aspiring youth making them reach the technical standards par global achievements, achievable through a balanced blend of impregnated tradition giving rooms to the indispensable evolutionary changes taking place in present scenario, through a structure of basic ethical values, dedication of the staff and high standards of technological infrastructural support. To evolve a system of education - the needs of the youthful India, to foster the creative individual and collective intelligence getting to surface the individualist latent talents without distorting the impregnated cultural, ethical and basic characteristic values. Mission
The diversified curriculum of education under one umbrella, prioritized to reach the deserving, capacitated youth assorted from socio economic backgrounds making them a promising product of our visionary institution. To provide education of high global standards with the able guidance of dedicated professionals and a state of art ambience and to produce an unparalleled group of technocrats and engineers with high acumen and expertise. To be in consonance with the national needs to reach the highest standards of quality education to those socio economically backward but deserving strata of youth yearning for their due share of participation in this field of education, breaking through the geographical proximities.
Laxmi Institute of Technology, Sarigam (Electronics And Communication Engineering Department)
Why Laxmi Institute of Technology?
Premier Institute of higher Education & Research.
Excellent track record for conduction campus placement events year after year.
Dynamism in Curriculum.
State of the art infrastructure, laboratories, libraries, classrooms.
Highly qualified & experienced faculty.
Leadership in quality education.
Excellent boarding & lodging facilities.
Round the clock high class perimeter security.
University ensures absolutely ragging free environment.
Strong industry-university interface ensuring excellent placement and training of students.
Leadership in quality education.
The pedagogy policy of university has its root in slogan,
“Empowering India through Education”
Laxmi Institute of Technology, Sarigam (Electronics And Communication Engineering Department)
ACADEMIC CALENDAR 2015-2016 Day
December
January
February
March
April
PA-I(1stsem)
1.
Sunday PA-III(1stsem)
2.
Sunday
3.
Sunday
PUT(4th& 2ndDipl)
PA-II(1stsem) PAIII(Deg&Dip
4.
PTM
5. 6.
May
Sunday
Sunday Sunday
7.
Mahashivratri PAII(4thsem& 2ndSem)
8.
Sunday
9.
Sunday
10.
Sunday
4thSem (Degree) & 2nd (Diplo.) Term Start
11.
4thSem (Degree) & 2nd (Diplo.) Term End
12. 13. 14.
Sunday
Sunday Makar Shankranti
Sunday
BabaAmbedkarjaynti
PAI(4 sem& nd 2 Diploma)
Ram Navmi
Sunday
th
15.
PUT(1stSem)
16. 17.
Sunday
Sunday
Laxmi Institute of Technology, Sarigam (Electronics And Communication Engineering Department)
PUT(6th& 8th; 18.
4th& 6th Diplo)
19.
Sunday
Sunday
2ndSem (Degree) Term End
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21.
6th& 8thSem (Degree) Term Start
Sunday
Sunday
22. 23.
Sunday
24.
Duleti
Sunday
25.
Republic Day
6th& 8th(Degree) Sem Term End
26.
Sunday
PA-I(6th& 8th , 4th& 6th (diplo))
PTM
4th& 6thSem (Diplo.) Term Start
2ndSem (Degree) Term Start
Sunday
27.
28.
29.
30.
Sunday
PAII(6thSem& 8thSem)
4th& 6thSem (Diplo.) Term End
PTM
Sunday
PTM
31.
Laxmi Institute of Technology, Sarigam (Electronics And Communication Engineering Department)
Degree
Diploma
2ndSem
4thSem
6thSem
8thsem
2ndSem
4thSem
6thSem
28-01-16
11-01-16
21-12-15
21-12-15
11-01-16
28-12-15
28-12-15
96
101
103
103
101
101
101
PA-I
01-03-16
15-02-16
27-01-16
27-01-16
15-02-16
27-01-16
27-01-16
PA-II
04-04-16
08-03-16
29-02-16
29-02-16
08-03-16
01-03-16
01-03-16
PA-III
02-05-16
04-04-16
04-04-16
04-04-16
04-04-16
04-04-16
04-04-16
PUT
16-05-16
02-05-16
18-04-16
18-04-16
02-05-16
18-04-16
18-04-16
Term End
20-05-16
11-05-16
26-04-16
26-04-16
11-05-16
29-04-16
29-04-16
GTU Exam
24-05-16
17-05-16
03-05-16
03-05-16
17-05-16
05-05-16
05-05-16
PTM-1
30-03-16
05-03-16
27-02-16
27-02-16
05-03-16
27-02-16
27-02-16
PTM-2
30-04-16
30-03-16
30-03-16
30-03-16
30-03-16
30-03-16
30-03-16
Term Start Working Days
Laxmi Institute of Technology, Sarigam (Electronics And Communication Engineering Department)
TABLE OF CONTENTS
S.No.
NAME OF TOPICS
1
SCHEME AND SYLLABUS
2
LECTURE PLAN
3
REFERENCES
4
PRACTICAL LECTURE PLAN WITH REFERENCES
5
UNITWISE BLOW-UP
6
QUESTION BANK
7
PREVIOUS YEAR QUESTION PAPER
Laxmi Institute of Technology, Sarigam (Electronics And Communication Engineering Department)
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Course of Study and Scheme of Examination for Batch starting from JAN 2016 B.E VI Semester (DEPARTMENT OF MECHANICAL ENGINEERING)
Mechanical Engineering (19)
Laxmi Institute of Technology, Sarigam (Mechanical Department)
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2161901
Dynamics of Machinery
Laxmi Institute of Technology, Sarigam (Mechanical Department)
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SYLLABUS
subject Name: Dynamics of Machinery Subject Code: 2161901
Teaching Scheme Theory
Tutorial
Practical
Evaluation Scheme Total
University Exam (Theory)
3
0
2
5
70
Mid Sem Exam
Practical
(Theory 30
50
UNIT-I: Balancing Need for balancing, Static balance, balancing of rotating masses in same and different planes, Numericals 1.1 Dynamic balancing, balancing of reciprocating masses, Numericals 1.2 Balancing of locomotives, Partial balancing of locomotives, swaying couple, hammer blow, variation in tractive effort,. Numericals 1.3 Balancing of multi cylinder in line engines, direct and reverse crank Concept, Numericals 1.4 Balancing of V and radial engines, Numericals, balancing machines
UNIT-II: Mechanical Vibrations Introduction, Degree of freedom, Types of vibrations, uses effects and remedy; free natural vibrations, Newton method and energy method for single degree of freedom.
2.1 Damped vibrations; under damped, critically damped and over damped systems, response curves for single degree of freedom system. Numericals 2.2 Forced vibrations with and without damping in single degree of freedom, rotating and reciprocating unbalance, base excitations, Numericals 2.3 Vibration Isolation and transmissibility; Force transmissibility, Motion transmissibility. Forced vibration with rotating and reciprocating Unbalance. Materials used in vibration isolation, Numericals Laxmi Institute of Technology, Sarigam (Mechanical Department)
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2.4 Longitudinal and Transverse Vibrations, whirling of shaft with a single disc with and without damping, Dunkerley's method for simply supported beams. 2.5 Torsional vibrations, torsionally equivalent system, stepped shafts and tapered shafts, two rotor, three rotor and geared systems,Numericals 2.6 Stodola’s and Holzer's method for multi rotor systems, Numericals 2.7 Two degree and Multi degree Vibrations, wave equation, boundary conditions in beams, solution of wave equation, Rayleigh's method, Numericals 2.8 Vibration measuring instruments, vibrometer, accelerometer and frequency measuring instruments
Laxmi Institute of Technology, Sarigam (Mechanical Department)
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LECTURE PLAN
Topics to be covered
Introduction of balancing, Need for balancing, Static balance
R1,R2
1
2
Numerical of static and dynamic balancing
R1,R2
3
Numerical of static and dynamic balancing
R1,R2 R1,R2
4
Balancing of rotating masses in same planes and different planes Balancing of rotating masses in same planes
R1,R2
5
Planned Date
Actual Date Teaching Aids/ of CompleBooks tion
Lec t
Signature of HoD & Date
and different planes (Numerical)
R1,R2 6
Balancing of rotating masses in different planes
7
Balancing of rotating masses in different planes(numerical)
8
Balancing of rotating masses in different planes(numerical)
9
Balancing of reciprocating masses, Numerical
10
Balancing of locomotives, Partial balancing of locomotives
11
Swaying couple, hammer blow, variation in tractive effort
R1,R2
R1,R2
R1,R2
R1,R2
R1,R2
Laxmi Institute of Technology, Sarigam (Mechanical Department)
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R1,R2 12
Swaying couple, hammer blow, variation in tractive effort, .Numerical
13
Swaying couple, hammer blow, variation in tractive effort, .Numerical
14
Balancing of multi cylinder in line engines
15
Direct and reverse crank concept, Numerical
16
Direct and reverse crank concept, Numerical
17
Balancing of V and radial engines
18
Balancing of V and radial engines( Numerical
19
Balancing of V and radial engines( Numerical
20
Balancing machines
21
Stodola’s and Holzer's method for multi rotor systems
22
Stodola’s and Holzer's method for multi rotor systems(Numerical)
23
Two degree and Multi degree Vibrations, wave equation,
24
Boundary conditions in beams, solution of wave equation
R1,R2
R1,R2
R1,R2
R1,R2
R1,R2
R1,R2
R1,R2
R1,R2 R1,R2
R1,R2
R1,R2
R1,R2
Laxmi Institute of Technology, Sarigam (Mechanical Department)
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R1,R2 Rayleigh's method, Numericals
Abvia-
R1,R2 26
Vibration measuring instruments, vibrometer
27
Accelerometer and frequency measuring instruments
bre-
R1,R2
R1,R2 Accelerometer and frequency measuring instruments tions used in the reference column are explained at the end of the Lecture Plan. 28
Reference Books: R1: “Theory Of Machines And Mechanisms” by J.E.Shigley, Tata Mcgraw Hill R2: “Dynamics Of Machines” by F. Haidery Nirali Prakashan, Pune
(iii) UNIT WISE (BLOW: UP) Laxmi Institute of Technology, Sarigam (Mechanical Department)
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UNIT-I BALANCING: Balancing is the technique of correcting or eliminating unwanted inertia forces or moments in rotating or reciprocating masses and is achieved by changing the location of the mass centers. The objectives of balancing an engine are to ensure: 1. That the centre of gravity of the system remains stationery during a complete revolution of the crank shaft and 2. That the couples involved in acceleration of the different moving parts balance each other.
Types of balancing: a) Static Balancing: i) Static balancing is a balance of forces due to action of gravity. ii) A body is said to be in static balance when its centre of gravity is in the axis of rotation. b) Dynamic balancing: i) Dynamic balance is a balance due to the action of inertia forces. ii) A body is said to be in dynamic balance when the resultant moments or couples, Laxmi Institute of Technology, Sarigam (Mechanical Department)
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ii) The conditions of dynamic balance are met; the conditions of static balance are also met. In rotor or reciprocating machines many a times unbalance of forces is produced due to inertia forces associated with the moving masses. If these parts are not properly balanced, the dynamic forces are set up and forces not only increase loads on bearings and stresses in the various components, but also unpleasant and dangerous vibrations. Balancing is a process of designing or modifying machinery so that the unbalance is reduced to an acceptable level and if possible eliminated entirely.
BALANCING OF ROTATING MASSES When a mass moves along a circular path, it experiences a centripetal acceleration and a force is required to produce it. An equal and opposite force called centrifugal force acts radially outwards and is a disturbing force on the axis of rotation. The magnitude of this remains constant but the direction changes with the rotation of the mass.
Laxmi Institute of Technology, Sarigam (Mechanical Department)
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In a revolving rotor, the centrifugal force remains balanced as long as the centre of the mass of rotor lies on the axis of rotation of the shaft. When this does not happen, there is an eccentricity and an unbalance force is produced. This type of unbalance is common in steam turbine rotors, engine crankshafts, rotors of compressors, centrifugal pumps etc. The unbalance forces exerted on machine members are time varying, impart vibratory motion and noise, there are human discomfort, performance of the machine deteriorate and detrimental effect on the structural integrity of the machine foundation. Balancing involves redistributing the mass which may be carried out by addition or removal of mass from various machine members.
Balancing of rotating masses can be of 1. Balancing of a single rotating mass by a single mass rotating in the same plane. 2. Balancing of a single rotating mass by two masses rotating in different planes. 3. Balancing of several masses rotating in the same plane 4. Balancing of several masses rotating in different planes Laxmi Institute of Technology, Sarigam (Mechanical Department)
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UNIT-II
Mechanical Vibrations Any motion that repeats itself after an interval of time is called vibration or oscillation. The swinging of a pendulum (Fig.1) and the motion of a plucked string are typical examples of vibration. The theory of vibration deals with the study of oscillatory motion of bodies and forces associate with them. Elementary Parts of Vi-
brating system • A means of storing potential energy (Spring or elasticity) • A means of storing kinetic energy (Mass or inertia) • A means by which energy is gradually lost (damper) The forces acting on the systems are • Disturbing forces • Restoring force • Inertia force • Damping force Degree of Freedom: The minimum number of independent coordinates required to determine completely the position of all parts of a system at any instant of time defines the degree of freedom of the system. System with a finite number of degrees of freedom are called discrete or lumped parameter system, and those with an infinite number of degrees of freedom are called continuous or distributed systems. Classification of Vibration: • Free and forced Laxmi Institute of Technology, Sarigam (Mechanical Department)
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• Damped and undamped • Linear and nonlinear • Deterministic and Random
Free vibration: If a system after initial disturbance is left to vibrate on its own, the ensuing vibration is called free vibration. Forced Vibration: If the system is subjected to an external force (often a repeating type of force) the resulting vibration is known as forced vibration Damped and undamped: If damping is present, then the resulting vibration is damped vibration and when damping is absent it is undamped vibration. The damped vibration can again be classified as under-damped, critically-damped and over-damped system depending on the damping ratio of the system. Fig. 1: Swinging of a Pendulum Linear vibration: If all the basic components of a vibratory system – the spring the mass and the damper behave linearly, the resulting vibration is known as linear vibration. Principle of superposition is valid in this case. Nonlinear Vibration: If one or more basic components of a vibratory system are not linear then the system is nonlinear. Depending on excitation: Deterministic: If the value or magnitude of the excitation (force or motion) acting on a vibratory system is known at any given time, the excitation is called deterministic. The resulting vibration is known as deterministic vibration.
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Random Vibration: In the cases where the value of the excitation at any given time cannot be predicted. Ex. Wind velocity, road roughness and ground motion during earth quake. Coordinate: In Newtonian mechanics motions are measured relative to an inertial reference frame, i.e, a reference frame at rest or moving uniformly relatively to an average position of “fixed stars” and displacement, velocity and acceleration are absolute values. Generalized coordinate: These are a set of independent coordinates same in number as that of the vibrating system. For example, the motion of a double pendulum in planar motion can be represented completely either by 1 2 θ θ, the rotation of the first and second link respectively or by 1 1 2 2 x y x y , , , the Cartesian coordinates of first and second links. While in the later case 4 coordinates are required to represent completely the system, in the former case only 2 coordinates are required for the same. Hence, in this case 1 2 θ θ, is the generalized co-ordinate while 1 1 2 2 x y x y , , , are not the generalized one. One may note that these four coordinates are not independent and can be reduced to two by the use of length constraint.
ASSIGNMENTS/ QUESTION BANK ASSIGNMENTS 1: Balancing of Rotating Masses Assignment Questions: 1) Four masses A, B, C and D carried by a rotating shaft are at radii 110, 140, 210 and 160 mm respectively. The planes in which the masses revolve are spaced 600 mm apart and the masses of B, C and D are 16 kg, 10 kg and 8 kg respectively. Find the required mass A and the relative angular positions of the four masses so that shaft is in complete balance. 2) Explain the methods of Static and Dynamic balancing using balancing machines in the industry.
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3) Four masses A, B, C, and D are completely balanced. Masses C and D make angles of 900 and 1950 respectively with B in the same sense. The rotating masses have following properties. mb = 25 kg ra = 150 mm mc = 40 kg rb = 200 mm md = 35 kg rc = 100 mm rd = 180 mm Planes B and C are 250 mm apart. Determine using analytical method, (i) The mass A and its angular position (ii) The positions of planes A and D. 4) A, B, C and D are four masses attached on a shaft at radii 0.1 m, 0.225 m, 0.15 m and 0.15 m respectively. Planes in which masses revolve are spaced 0.6 m apart and the weights of B, C and D are 10 kg, 5.5 kg and 3.6 kg respectively. Find the required mass at A and the relative angular positions of all the four masses so that the shaft is in complete balance. Use any method. 5) Derive an expression for the response of a rotating unbalance system. Plot the amplitude frequency response curves for different damping factors.
ASSIGNMENTS 2: Balancing of Reciprocating Masses Assignment Questions: 1) How and why are reciprocating masses balanced in a piston-cylinder assembly? Why reciprocating masses are partially balanced? 2) The crank radius and connecting rod length of a four cylinder inline engine are 200 mm and 900 mm respectively. The outer cranks are set at 120o to each other and each has a reciprocating mass of 200 kg. The spacing between adjacent planes of cranks are 400 mm, 600 mm and 500 mm. If the engine is in complete primary balance, determine the reciprocating masses of the inner cranks and their angular positions. Also find the secondary unbalanced force if the engine speed is 300 rpm. 3) Explain the procedure for balancing multi-cylinder radial engines by direct and reverse cranks method. Attempt the following questions. (i) Need of balancing (ii) Primary unbalanced force in reciprocating engine. (iii) Four examples of practical problems where balancing is done. Laxmi Institute of Technology, Sarigam (Mechanical Department)
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4) A five cylinder in-line engine running at 750 r.p.m. has successive cranks 1440 apart, the distance between the cylinder centre lines being 375 mm. The piston stroke is 225 mm and the ratio of the connecting rod to the crank is 4. 5) Examine the engine for balance of primary force and couple. Find the maximum values of these and the position of the central crank at which these maximum values occurs. The reciprocating mass for each cylinder is 15 kg. The reciprocating mass per cylinder in a 600 twin engine is 1.5 kg. The stroke and connecting rod length are 100 mm and 250 mm respectively. If the engine runs at 2500 r.p.m. Determine the maximum and minimum values of the primary forces. Also find out the resultant secondary force. 6) A single cylinder engine runs at 250 rpm and has a stroke of 180 mm. The reciprocating parts weigh 120 kg and revolving parts equivalent to 70 kg at a radius of 90 mm. A mass is kept opposite to the crank at a radius of 150 mm to balance the whole of revolving mass and two third of the reciprocating mass. Determine the magnitude of balancing mass and the resultant residual unbalanced force when the crank has turned 300 from the dead centre.
ASSIGNMENTS 3: Balancing of Locomotives V Engines Assignment Questions: 1) The following data refers to an inside cylinder locomotive: Mass of reciprocating parts/cylinder: 36 kg Revolving masses/cylinder : 16 kg Pitch of the cylinder : 700 mm Angle between crank : 90o Length of each crank : 320 mm Wheel tread diameter : 1900 mm Distance between planes of wheel : 1800 mm Limiting speed of locomotive : 100 kmph If total revolving masses and 2/3 of the reciprocating parts are to be balanced, determine: (i) Variation of tractive force (ii) Maximum swaying couple.
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2) The intermediate cranks of a four cylinder symmetrical engine, which is in complete primary balance, are 90o to each other and each has a reciprocating mass of 300 kg. The centre distance between intermediate cranks is 600 mm and between extreme cranks it is 1800 mm. Lengths of the connecting rod and cranks are 900 mm and 300 mm respectively. Calculate the masses fixed to the extreme cranks with their relative angular positions. Also find the magnitudes of secondary forces and couples about the centre line of the system if the engine speed is 1500 rpm. 3) Discuss the method of Balancing of V-engines and determine the expression for magnitude and direction of resultant primary force. 4) For uncoupled two cylinder locomotive engine, explain the following terms: (i) Hammer blow (ii) Swaying couple (iii) Variation in tractive force 5) For a twin V-engine the cylinder centerlines are set at 90o. The mass of reciprocating parts per cylinder is 2.5 kg. Length of crank is 100 mm and length of connecting rod is 400 mm. determine the primary and secondary unbalanced forces when the crank bisects the lines of cylinder centerlines. The engine runs at 1000 rpm. 6) The three cranks of three cylinder locomotive are all on the same axle and are set at 1200 .The pitch of the cylinders is 1 meter and the stroke of each piston is 0.6 m. The reciprocating masses are 300 kg for inside cylinder and 260 kg for each outside cylinder and the planes of rotation of the balance masses are 0.8 m from the inside crank. If 40% of the reciprocating parts are to be balanced, Find:1. The magnitude and the position of the balancing masses required at a radius of 0.6 m. 2. The hammer blow per wheel when the axle makes 6 r.p.s 7) Discuss balancing of ‘V’ engines. 8) Explain the concept of direct and reverse crank for balancing of radial engines. 9) For an uncoupled two cylinder locomotive engine, derive (a) Variation in tractive force, (b) Hammer blow and (c) Swaying couple.
ASSIGNMENTS 4: Introduction to vibrations
Assignment Questions: 1) Define the following: Simple harmonic motion, Transmissibility, Resonance, Dynamic Magnification Factor, Degree of freedom, Damping factor, Natural frequency of vibration. 2) Discuss the effect of damping on vibratory systems. What is meant by under damping, critical damping and over damping? 3) Define the following terms: Natural frequency, Damping factor, Logarithmic decrement, Resonance, Critical speed of the shaft, Magnification factor and Force transmissibility. Laxmi Institute of Technology, Sarigam (Mechanical Department)
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4) What are different approaches to get equations of motion of a vibratory system? Explain any one in brief.
ASSIGNMENTS 5: Forced vibration
1) A machine having mass of 100 kg is mounted on four springs of combined stiffness 1500 kN/m with an estimated damping factor of 0.25. A piston within the machine has a mass of 2 kg which reciprocates with stroke of 80 mm at a speed of 3000 rpm. Assuming the motion of the piston to be SHM, determine: (i) The amplitude of the steady state vibration.(ii) The force transmitted to the foundation.(iii) Magnification factor. 2) The electric motor is supported on a spring and a dashpot. The spring has the stiffness 6400 N/m and the dashpot offers resistance of 500 N at 4.0 m/sec. The unbalanced mass 0.5 kg rotates at 50 mm radius and the total mass of vibratory system is 20 kg. The motor runs at 400 r.p.m. Determine (a) damping factor (b) amplitude of vibration and phase angle (c) resonant speed and amplitude 3) A vibratory body of mass 150 kg supported on springs of total stiffness 1050 kN/m has a rotating unbalance force of 525 N at a speed of 6000 r.p.m. If the damping factor is 0.3, Determine (i) the amplitude caused by the unbalance and its phase angle (ii) the transmissibility The successive amplitudes of vibrations of a vibratory system as obtained under free vibrations are 0.69, 0.32, 0.19 and 0.099 units respectively. 4 ) Determine the damping ratio of the system. If the damping ratio is doubled what would be the amplitude ratio then? 5)A single cylinder engine has a mass of 100 kg and is acted upon by a vertical unbalanced force of 400sin(13πt ) N. The engine block is supported on a spring having a stiffness 60 kN/m and a damper which gives a damping force of 700 N per unit velocity. Find the damping ratio and force transmitted to the foundation.
ASSIGNMENTS 6: Critical Speed of Shafts
1 )Derive an expression to determine deflection of a shaft simply supported at two ends, carrying single rotor at the center, rotating at an angular speed ω, considering damping. 2) A shaft 100 mm diameter is simply supported in two bearings 4 m apart carrying three discs having masses 125 kg, 200 kg and 100 kg situated at 1.5 m, 2 m and 3 m from one of the bearings respectively. Determine the frequency of transverse vibration of the beam by Dunkerley’s method. Neglect mass of the beam. Assume E = 2 x 105 MPa.
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3) A shaft 40 mm diameter and 2.5 m long is supported between two short bearings at its ends. It carries three rotors of masses 90 kg, 140 kg and 60 kg at 0.8 m, 1.5 m and 2 m from the left bearing respectively. Take Young’s modulus of the shaft material as 2×105 N/mm2 and neglecting the mass of the shaft determine the critical speed of the shaft by using Dunkerley’s method. 4 )Answer the following questions. (i) Explain briefly energy method to find out characteristic equation for free vibration of single degree of freedom system. (ii) Define under-damped system. (iii) Define briefly whirling speed of shaft with single disc without damping.
Laxmi Institute of Technology, Sarigam (Mechanical Department)
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Roll No.________
Enrollment No.___________Student sign:-_________ Gujarat Technological University LAXMI INSTITUTE OF TECHNOLOGY, SARIGAM Academic year 2014-2015 Semester Exam B. E. – III(Sem – 6) Branch: Mechanical Engineering
Subject: Dynamic of machine Date: 27/04/2015
Subject Code: 161901
Time: 1:00 pm to 3.30 pm
Max. Marks:70
Instructions: 1. Attempt all questions. 2. Make suitable assumptions wherever necessary. 3. Figures to the right indicate full marks. Q.1
Q.2
A) Explain in briefa) Need of balancing b)primary unbalanced force c)four example of practical problem where balancing is done B) What is vibration and Classification of vibration also discuss advantage and disadvantage of vibration also Define time period, amplitude A) Explain brief primary and secondary balancing of reciprocating masses
B) Four masses m1,m 2,m 3,m 4 having their radii of rotation as
7 Marks
7 Marks 7 Marks
7 Marks
100mm,120mm, 250mm, 300mm are 200kg,250kg,150kg and 100kg respectively. The angle between successive masses are 45°,70° and 140°respectively Find position and magtitude of balancing mass required if its radius of rotation is 350mm Solve by graphical method OR Q.2
A). Define Static & Dynamic balancing with suitable example also discuss why is balancing of rotating parts necessary for high speed engine
7 Marks
7 Marks B) Four masses A, B, C, and D are completely balanced. Masses C and D make angles of 90°and 195° respectively with B in the same sense. The rotating masses have following properties. mb = 25 kg ra = 150 mm mc = 40 kg rb = 200 mm md = 35 kg rc = 100 mm rd = 180 mm Planes B and C are 250 mm apart. Determine using analytical method, Laxmi Institute of Technology, Sarigam (Mechanical Department)
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(i) The mass A and its angular position (ii) The positions of planes A and D. Solve by graphical method
Q.3
A) Explain balancing machine with the neat sketch
7 Marks
B) Four masses 150 kg, 200 kg, 100 kg and 250 kg are attached to a shaft revolving at radii 150 mm, 200 mm, 100 mm and 250 mm ; in planes A, B, C and D respectively. The planes B, C and D are at distances 350 mm, 500 mm and 800 mm from plane A. The masses in planes B, C and D are at an angle 105°, 200°and 300° measured anticlockwise from mass in plane A. It is required to balance the system by placing the balancing masses in the planes P and Q which are midway between the planes A and B, and between C and D respectively. If the balancing masses revolve at radius 180 mm, find the magnitude and angular positions of the balance masses.
7 Marks
7 Marks Q.4
OR A)Explain different method in vibrating system also Define Frequency, degree of freedom. B) A single cylinder reciprocating engine has speed of 240rpm , stroke 300mm, mass of reciprocating parts 50kg, mass of revolving parts at 150mm radius 30kg .if all the mass of revolving parts and two third of mass of reciprocating parts are to be balanced, find the balance mass required at radius of 400mm and the residual unbalanced force when the crank has rotated 60° from IDC
Q5
A)Explain in briefFor uncoupled two cylinder locomotive engine-Variation in tractive force & swaying couple B) Enlist different types of vibration measuring instrument .Explain any one in detail OR A) The following data refers to an inside cylinder locomotive: Mass of reciprocating parts/cylinder: 36 kg Revolving masses/cylinder : 16 kg Pitch of the cylinder : 700 mm Angle between crank : 90o Length of each crank : 320 mm Wheel tread diameter : 1900 mm Distance between planes of wheel : 1800 mm Limiting speed of locomotive : 100 kmph If total revolving masses and 2/3 of the reciprocating parts are to be balanced, determine: (i) Variation of tractive force (ii) Maximum swaying couple
7Marks
7 Marks
7 Marks
7 Marks
7 Marks B) Explain the concept of critical damped and over damped system Laxmi Institute of Technology, Sarigam (Mechanical Department)
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A) Explain the procedure for balancing multi-cylinder radial engines
7 Marks
B) What are various frequency measuring instruments? Explain in brief
7 Marks
Q.5
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SEAT NO.: _____________ENROLMENT NO.________________
GUJARAT TECHNOLOGICAL UNIVERSITY B E Sem-VI Examination May 2011 Subject code: 161901 Subject Name: Dynamics of Machinery Date:16/05/2011
Time: 10.30 am – 01.00 pm Total Marks: 70
Instructions: 1.Attempt all questions. 2.Make suitable assumptions wherever necessary. 3.Figures to the right indicate full marks. Q.1
Q.2
Q.3
(a) What are different approaches to get equations of motion of a vibratory system? Explain any one in brief.
07
(b) Discuss different cases showing the characteristics of the system performance for a damped free vibration.
07
(a) A, B, C and D are four masses attached on a shaft at radii 0.1 m, 0.225 m, 0.15 m and 0.15 m respectively. Planes in which masses revolve are spaced 0.6 m apart and the weights of B, C and D are 10 kg, 5.5 kg and 3.6 kg respectively. Find the required mass at A and the relative angular positions of all the four masses so that the shaft is in complete balance. Use any method.
07
(b) A single cylinder engine has a mass of 100 kg and is acted upon by a vertical unbalanced force of 400sin(13πT) N. The engine block is supported on a spring having a stiffness 60 kN/m and a damper which gives a damping force of 700 N per unit velocity. Find the damping ratio and force transmitted to the foundation. OR (b) Derive an expression for the response of a rotating unbalance system. Plot the amplitude frequency response curves for different damping factors.
07
(a) Derive an expression for finding natural frequency of a cylindrical object having a radius r, which is rolling without slipping and vibrating inside a circular surface of radius R.
07
07
(b) A rotor has a mass of 12 kg mounted midway on a 24 mm diameter horizontal 07 shaft supported at the ends by two bearings which are 1 m apart. The shaft rotates at 2400 rpm. If the centre of mass m of the rotor is 0.11 mm away from geometric centre of the rotor due to certain manufacturing defects, find the natural frequency, amplitude of the steady state vibration and dynamic force Laxmi Institute of Technology, Sarigam (Mechanical Department)
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transmitted to the bearings. The shaft is assumed to be simply supported. Take modulus of elasticity as 200 GPa. OR Q.3
A) Explain balancing machine with the neat sketch
7 Marks
B) Four masses 150 kg, 200 kg, 100 kg and 250 kg are attached to a shaft revolving at radii 150 mm, 200 mm, 100 mm and 250 mm ; in planes A, B, C and D respectively. The planes B, C and D are at distances 350 mm, 500 mm and 800 mm from plane A. The masses in planes B, C and D are at an angle 105°, 200°and 300° measured anticlockwise from mass in plane A. It is required to balance the system by placing the balancing masses in the planes P and Q which are midway between the planes A and B, and between C and D respectively. If the balancing masses revolve at radius 180 mm, find the magnitude and angular positions of the balance masses.
7 Marks
7 Marks Q.4
OR A)Explain different method in vibrating system also Define Frequency, degree of freedom. B) A single cylinder reciprocating engine has speed of 240rpm , stroke 300mm, mass of reciprocating parts 50kg, mass of revolving parts at 150mm radius 30kg .if all the mass of revolving parts and two third of mass of reciprocating parts are to be balanced, find the balance mass required at radius of 400mm and the residual unbalanced force when the crank has rotated 60° from IDC
Q5
A)Explain in briefFor uncoupled two cylinder locomotive engine-Variation in tractive force & swaying couple
7Marks
7 Marks
B) Enlist different types of vibration measuring instrument .Explain any one in detail OR A) The following data refers to an inside cylinder locomotive: Mass of reciprocating parts/cylinder: 36 kg Revolving masses/cylinder : 16 kg Pitch of the cylinder : 700 mm Angle between crank : 90o Length of each crank : 320 mm Wheel tread diameter : 1900 mm Distance between planes of wheel : 1800 mm Limiting speed of locomotive : 100 kmph If total revolving masses and 2/3 of the reciprocating parts are to be balanced, determine: (i) Variation of tractive force (ii) Maximum swaying couple
7 Marks
B) Explain the concept of critical damped and over damped system
7 Marks
7 Marks
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A) Explain the procedure for balancing multi-cylinder radial engines
7 Marks
B) What are various frequency measuring instruments? Explain in brief
7 Marks
Q.5
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2161902 Internal combustion engines
Laxmi Institute of Technology, Sarigam (Mechanical Department)
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SYLLABUS Category of Course Automobile
Course Title Internal combustion engines
Course Code 2161902
Theory Paper L
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UNIT-I Introduction: Basic components and terminology of IC engines, working of four stroke/two stroke - petrol/diesel engine, classification and application of IC engines, engine performance and emission parameters UNIT-II Fuel Air Cycles and Actual Cycles: Assumptions for fuel–air cycles, Reasons for variation of specific heats of gases, change of internal energy and enthalpy during a process with variable specific heats, isentropic expansion with variable specific heats, effect of variable specific heats on Otto, Diesel and Dual cycle, dissociation, comparison of air standard and fuel air cycles, effect of operating variables, comparison of air standard and actual cycles, effect of time loss, heat loss and exhaust loss in Petrol and Diesel engines, valve and port timing diagrams UNIT-III Combustion: Combustion equations, stoichiometric air fuel ratio, enthalpy of formation, adiabatic flame temperature, determination of calorific values of fuels – calorimeter*- Bomb and Junkers gas calorimeter UNIT-IV Fuels and its supply system for SI and CI engine: Important qualities of IC engine fuels, rating of fuels, Carburation, mixture requirement for different loads and speeds, simple carburetor and its working, types of carburetors, MPFI, types of injection systems in CI engine, fuel pumps and injectors, types of nozzles, spray formation. UNIT – V Ignition and Governing System: Battery and magneto ignition system, spark plug, firing order, quality, quantity & hit and miss governing UNIT – VI Supercharging: Need for supercharging, Effect of supercharging, types of supercharger, methods of supercharging, thermodynamic analysis of supercharged engine cycle, limitations of supercharging, turbocharging UNIT – VII Combustion in SI and CI Engines: Stages of combustion in SI engines, abnormal combustion and knocking in SI engines, factors affecting knocking, effects of knocking, control of knocking, combustion chambers for SI engines, Stages of combustion in CI engines, detonation in C.I. engines, factors affecting detonation, controlling detonation, combustion chamber for SI and CI engine UNIT – VIII Engine Lubrication and Cooling: Lubrication of engine components, Lubrication system – wet sump and dry sump, crankcase ventilation, Types of cooling systems – liquid and air cooled, comparison of liquid and air cooled systems UNIT – IX Measurement and Testing of IC engines: Measurement of indicated power, brake power, fuel consumption and emission, Measurement of friction power by Willan’s Line Method* and Morse Test*, calculation of brake thermal efficiency, brake power and brake specific fuel consumption of IC Engines, variable compression ratio engines, heat balance sheet of IC Engines Laxmi Institute of Technology, Sarigam (Mechanical Department)
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UNIT – X Engine Emission and their control: Air pollution due to IC engines, Euro I to VI norms, HC, CO and NOx emission, catalytic convertor UNIT – XI Application of diesel engines in power field Application of diesel engines in power field, merit and demerits of diesel engine power plants, layout of diesel engine power plants
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LECTURE PLAN
Lect
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Topics to be covered
Introduction of I.C engine, applications, theoretical working of IC engines. Overview of Otto cycle and Diesel cycle, actual working of I.C engine, Valve and port timing diagrams. Fuel air cycles, actual cycles and their analysis. Factors considered and assumptions made for fuel–air cycles, dissociation, comparison of air standard and fuel air cycles. Effect of operating variables on cycle analysis, difference between actual cycle and fuel air cycle for SI and CI engines. Desirable properties of I.C. engine fuels, required qualities of S.I and C.I engine fuels, rating of S.I and C.I. engine fuels. Rating of S.I and C.I. engine fuels, HUCR, dopes/additives for S.I. & C.I. engines. Use of alternate fuels like CNG, LNG, LPG, vegetable oils, biodiesel.
Planned Date
Actual Date of Completion
Teaching Aids/ Books
Signature of HoD & Date
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Use of alcohol, biogas and hydrogen for IC engines.
1st UNIT TEST (25% of Syllabus) Fuel supply system for SI engines, properties of air-petrol mixture, mixture requirement for different loads and speeds. Simple carburetor and its working, calculation of air-fuel ratio, types of carburetors. Limitations of a single jet carburetor, modern carburetors. Problems in carburetors, altitude compensation, gasoline injection in SI engines.
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MPFI system for modern automobile engines. Fuel supply systems for C.I. engines: Requirement of ideal injection system.
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Types of injection systems, fuel pumps and injectors.
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Types of nozzles, spray formation.
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Quantity of fuel and size of nozzle orifice. Objects, types of superchargers. Supercharging of SI and CI engines. Effects of supercharging, supercharging limits. Methods of supercharging, turbo charging. Combustion in S.I. Engines: Stages of combustion, Ignition lag and the factors affecting the ignition lag. Flame propagation and factors affecting flame propagation. MID SEMESTER (50% of Syllabus) Abnormal combustion and knocking in SI engines, factors affecting knocking, effects of knocking, control of knocking. Combustion chambers for S.I. engines. Combustion in C.I. engines: Stages of combustion. Delay period /ignition lag and the factors affecting it. Detonation in C.I. engines, factors affecting detonation, controlling detonation. Combustion chambers for C.I. engines. Aims of engine testing, measurement of indicated power. 2st UNIT TEST (75% of Syllabus) Testing of brake power, friction power, speed. Testing of air consumption, fuel consumption. Testing of IC engine efficiencies, specific output. Testing of specific fuel consumption, heat balance sheet.
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Performance characteristics of SI and CI engines, testing of IC engines as per Indian standard 10001. Working principle of Stirling, Wankle and Variable Compression Ratio Engines Introduction of I.C engine, applications, theoretical working of IC engines. Overview of Otto cycle and Diesel cycle, actual working of I.C engine, Valve and port timing diagrams. Fuel air cycles, actual cycles and their analysis. Factors considered and assumptions made for fuel–air cycles, dissociation, comparison of air standard and fuel air cycles. Effect of operating variables on cycle analysis, difference between actual cycle and fuel air cycle for SI and CI engines. Aims of engine testing, measurement of indicated power. Testing of brake power, friction power, speed. Testing of air consumption, fuel consumption. Testing of IC engine efficiencies, specific output. Testing of specific fuel consumption, heat balance sheet. Performance characteristics of SI and CI engines, testing of IC engines as per Indian standard 10001.
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Put 100% syllabus REFERENCES S. No.
1
2
TITLE
AUTHOR
Internal Combustion Engines
V Ganesan.
PUBLISHER / EDITION Tata-McGraw Hill Publishing Co., New Delhi
YEAR
2013
A course in Internal Combustion Engines
V.M.Domkundwar
Dhanpatrai publications
2014
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3
Internal Combustion Engines
J.P HADIYA
Books India Publications
2014
4
Automobile Engines
K.V.Kadadu
Books India Publications
2015
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UNITWISE BLOWUP UNIT-I Engine Construction and Operation
The four-stroke cycle operates through two revolutions of the crankshaft. The intake stroke draws air and fuel into the cylinder. The compression stroke compresses the air-fuel mixture. When the mixture ignites, it pushes the piston down for the power stroke. On the exhaust stroke, the upward movement of the piston pushes the exhaust gases out of the cylinder. The cycle then repeats. The major components of a reciprocating-piston engine are the engine block, pistons and rings, connecting rods, crankshaft, cylinder head(s), valves, and valve train. The valves are driven by the crankshaft through a set of gears, a gear and chain arrangement, or sprockets and a drive belt. On some engines, valve operation is controlled by a mechanism operated by a computer. The cooling system removes unwanted engine heat and regulates engine temperature. Cars and light trucks have a liquid cooling system. Coolant is pumped through engine passages by a belt-driven pump. A radiator removes heat from the coolant. Engine coolant is a mixture of antifreeze and water. Antifreeze may be ethylene glycol or propylene glycol. Poor lubrication can eventually result in driveability symptoms. The lubrication system circulates engine oil to internal engine parts. Oil galleries are internal passages that carry the oil throughout the engine. The oil pump is driven by a gear on the camshaft or by the engine timing belt. A pressure regulator controls oil pump output. The engine oil provides lubrication, reduces friction, helps with cooling, seals, provides shock absorption between parts, and cleans parts. It is formulated to prevent sludge formation.
Figure: Petrol Engine
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UNIT-II Two stroke engine The two-stroke cycle engine (commonly called two-cycle) performs the same cycle of events as the four-cycle engine. The main difference is that intake, compression, power, and exhaust functions take place during only two strokes of the piston. The two strokes occur during each revolution of the crankshaft. Therefore, it takes only one revolution of the shaft to complete a two-stroke cycle. A two-cycle engine has several advantages over a four-cycle unit. It is much simpler in design than the four-cycle engine because the conventional camshaft, valves, and tappets are unnecessary. See Figure. Additionally, a two-cycle engine is smaller and lighter than a four-cycle engine of equivalent horsepower. Unlike the four-stroke cycle engine, the two-cycle engine will get adequate lubrication even when operated at extreme angles. It receives its lubrication as fuel mixed with oil is passed through the engine.
Figure : Two Stroke Engine Four Stroke Engine In a four-stroke cycle engine (called a fourcycle), four strokes are needed to complete the operating cycle. The four strokes are as follows: • intake stroke • compression stroke • power stroke • exhaust stroke Two strokes occur during each revolution of the crankshaft. Therefore, a four-stroke cycle requires two revolutions of the crankshaft. Figure. Illustrates each of the four strokes taking place in proper
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Figure: four stroke Engine cycle UNIT –III SI Engine Fuel System Spark-ignition engines normally use volatile liquid fuels. Preparation of fuel-air mixture is done outside the engine cylinder and formation of a homogeneous mixture is normally not completed in the inlet manifold. Fuel droplets, which remain in suspension, continue to evaporate and mix with air even during suction and compression processes. The process of mixture preparation is extremely important for sparkignition engines. The purpose of carburetion is to provide a combustible mixture of fuel and air in the required quantity and quality for efficient operation of the engine under all conditions. Definition of Carburetion The process of formation of a combustible fuel-air mixture by mixing the proper amount of fuel with air before admission to engine cylinder is called carburetion and the device which does this job is called a carburetor. Factors Affecting Carburetion Of the various factors, the process of carburetion is influenced by i. The engine speed ii. The vaporization characteristics of the fuel iii. The temperature of the incoming air and iv. The design of the carburetor
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Figure : Carburetor UNIT –IV CI Engine Fuel System The C.I. engine demands that the fuel supplied is –Timed to inject when the piston is near the end of the compression stroke.The fuel is atomised (broken up) into fine particles if efficient combustion and reduced pollution are to be obtained.The fuel is forced with sufficient pressure into to the hot air in the combustion engine.All C.I.engines require some form of cold start device, this is because when the engine is cold, heat loss can result in the heat generated by the compression stroke insufficient to ignite the fuel. To overcome this, most C.I.engine inject addition fuel when cold (excess fuel) and use some form of electrical heating device, to raise the temperature of the air (glow plugs).If theses demands are not met, the engine will produce excessive noise (combustion knock) and pollution. The fuel system consists basically of a fuel tank, one or more filters, a low pressure fuel (lift) pump, a high pressure injection pump and a injector for each cylinder. Air must not be allowed to get into the fuel injection system, the engine will not run, some systems require bleeding if air is presen, e.g. when the fuel filter is replaced, or the vehicle runs out of fuel
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Figure: Fuel Injection System UNIT –V Cooling and Lubrication System A system, which controls the engine temperature, is known as a cooling system. Necessity Of Cooling System : The cooling system is provided in the IC engine for the following reasons: • The temperature of the burning gases in the engine cylinder reaches up to 1500 to 2000°C, which is above the melting point of the material of the cylinder body and head of the engine. (Platinum, a metal which has one of the highest melting points, melts at 1750 °C, iron at 1530°C and aluminium at 657°C.) Therefore, if the heat is not dissipated, it would result in the failure of the cylinder material. • Due to very high temperatures, the film of the lubricating oil will get oxidized, thus producing carbon deposits on the surface. This will result in piston seizure. • Due to overheating, large temperature differences may lead to a distortion of the engine components due to the thermal stresses set up. This makes it necessary for, the temperature variation to be kept to a minimum. • Higher temperatures also lower the volumetric efficiency of the engine. Requirements Of Efficient Cooling System The two main requirements of an efficient cooling system are: 1. It must be capable of removing only about 30% of the heat generated in the combustion chamber. Too much removal of heat lowers the thermal efficiency of the engine. 2. It should remove heat at a fast rate when the engine is hot. During the starting of the engine, the cooling should be very slow so that the different working parts reach their operating temperatures in a short time. Types Of Cooling System There are two types of cooling systems: (i) Air cooling system and (ii) Water-cooling system. Lubrication system: The engine lubrication system is designed to deliver clean oil at the correct temperature and pressure to every part of the engine. The oil is sucked out the sump into the pump, being the heart of the system, than forced through an oil filter and pressure feeded to the main bearings and to the oil pressure gauge. From the main bearings, the oil passes through feed-holes into drilled passages in the crankshaft and on to the big-end bearings of the connecting rod. The cylinder walls and piston-pin bearings are lubricated by oil fling dispersed by the rotating crankshaft. The excess being scraped off by the lower ring in the piston. A bleed or tributary from the main supply passage feeds each camshaft bearing. Another bleed supplies the timing chain or gears on the camshaft drive. The excess oil then drains back to the sump, where the heat is dispersed to the surrounding air. Types of lubricating (oil) systems . The systems used to circulate oil are known as splash, combination splash force feed, force feed, full force-feed.
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UNIT –VI Combustion and Combustion Chambers: The combustion process : The combustor provides the energy input for the gas turbine cycle. It receives air, inserts fuel, mixes the two components and then it lets the mixture combust. This process is known as internal combustion. In a gas turbine, it is generally done at constant pressure. (Although small pressure losses are generally present.) An important parameter during combustion is the T04 temperature. It effects the power output and the thermal efficiency. T04 is generally limited by material properties. The materials must be able to withstand large temperatures and temperature gradients. If not, the gas turbine might fail. Combustion Chamber: Intake manifold design and combustion chamber shape effects the gas flow and turbulence intensity. Turbulence strongly effects burning rate of the fuel. Spark plug location effects distance traveled by the flame and flame front surface area. Number of spark plugs. Pressure gradiant should be controlled for optimum conditions in terms of total efficiency. For best efficiency :
UNIT –VII Types of Scavenging. In automotive usage, scavenging is the process of pushing exhausted gas-charge out of the cylinder and drawing in a fresh draught of air or fuel/air mixture for the next cycle. This process is essential in having a smooth-running internal combustion engine. If scavenging is incomplete, the following stroke will begin with a mix of exhaust fumes rather than clean air. This may be inadequate for proper combustion, leading to poor running conditions such as four-stroking. Scavenging is equally important for both two- and four-stroke engines. However it is more difficult to achieve in two-stroke engines, owing to the proximity, or even overlap, of their induction and exhaust strokes. Scavenging is also equally important to both petrol and diesel engines. There are three types of scavenging on the basis of the flow of air:
Direct, cross or loop scavenging
Reverse, using Schnuerle porting Uniflow scavenging
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Figure :Types of Scavenging
UNIT – VIII Supercharging and Turbo charging: Super charger: A turbocharger is basically a centrifugal compressor driven by a turbine which is run by the exhaust gases or emission gases coming out of the your car’s engine. The compressor used in the construction compresses the air which is about to enter the engine, to high pressure. With increased pressure, the weight or amount of fuel entering the same space inside the engine is increased. In this way, the burning of fuel is more efficient inside the engine chamber and it eventually results in greater performance of the vehicle from the same displacement of engine without need of a larger displacement engine. For example, if you put 30% more fuel in the same engine cylinder, the burning of that fuel will produce about 30% more power from the same size of engine.
Figure:Supercharger
TurboCharger: A supercharger is very much similar to a turbocharger with a compressor used for forcing high pressure air into the engine. The major difference being that in case of the supercharger, the engine itself runs the turbocharger whereas in turbocharger, the energy of escaping exhaust gases or emission, which otherwise goes waste, is used to run the compressor. With more compressed air, more oxygen and fuel reaches the combustion chamber, hence more power is developed.
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Figure: Turbocharger UNIT – IX Engine Testing and Performance: Laboratory work on engine testing is intended to bring students into contact with running engines, allowing the student a) to learn the basic procedures of engine testing ; b) to verify, measure, and interpret engine performance and how this performance changes when the test conditions change ; and c) to “feel” the engine, i.e., to develop sensorial awareness to how a running engine sounds, smells, vibrates, realises heat, etc. In particular it is intended that each student is directly involved in (and responsible for) one of the following engine tests (and writes the corresponding report), and participates in at least one of the other tests: influence of load at constant speed in a Diesel engine; influence of load at constant speed in a Diesel engine with retarded injection; influence of load at constant speed in a spark ignition (SI) engine; influence of engine speed in a SI engine for constant throttle position; influence of ignition timing at constant speed and constant throttle position in a SI engine; influence of air/fuel ratio at constant speed and constant throttle position in a SI engine; influence of compression ratio at constant speed and constant throttle position in a SI engine. UNIT – X Engine Emission and their control There has been a great concern, in recent years, that the I C Engines are e I C Engines are I C Engines are responsible responsible for too much atmospheric pollution, which is for too much atmospheric pollution, which isdetrimental to human health & detrimental to human health & detrimental to human health &environment. environment. Thus concerted efforts are being made to reduce the re Thus concerted efforts are being made to reduce the responsible pollutants emitted sponsible pollutants emitted from the exhaust system without sacrificing power & from the exhaust system without sacrificing power & em without sacrificing power &fuel consumption. fuel consumption. fuel consumption. Air pollution can be defined as an addition to our atmosphere of any material which will have a deleterious effect on life upon our planet. Besi have a deleterious effect on life upon our planet. Besides IC engines other sources engines other sources such as electric power stations, industrial and domestic fuel consumers also add pollution. Pollution Pollutants are produced Pollutants are produced by the incomplete burning of the air by the incomplete burning of the air by the incomplete burning of the air-fuel mixture in the fuel mixture in the combustion chamber. Laxmi Institute of Technology, Sarigam (Mechanical Department)
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The major pollutants emitted from the exhaust due to incomplete combustion are: combustion are: Carbon monoxide (CO) Carbon monoxide (CO) Hydrocarbons (HC) Hydrocarbons (HC) Oxides of nitrogen (NO). Oxides of nitrogen (NO). Other products produced are acetylene, aldehydes etc. If, Other products produced are acetylene, aldehydes etc. If, ene, aldehydes etc. If, however, combustion however, combustion however, combustion is complete- complete--the only products being expelled from the exhaust would the only products being expelled from the exhaust would be water vapour e water vapour which is harmless, and carbon dioxide, which is an inert gas and, as such it is not directly harmful to humans. UNIT – XI Application of diesel engines in power field A generating station in which diesel engine is used as the prime mover for the generation of electrical energy is known as diesel power station. In a diesel power station, diesel engine is used as the prime mover. The diesel burns inside the engine and the products of this combustion act as the working fluid to produce mechanical energy. The diesel engine drives alternator which converts mechanical energy into electrical energy. As the generation cost is considerable due to high price of diesel, therefore, such power stations are only used to produce small power. Although steam power stations and hydro-electric plants are invariably used to generate bulk power at cheaper costs, yet diesel power stations are finding favour at places where demand of power is less, sufficient quantity of coal and water is not available and the transportation facilities are inadequate. This plants are also standby sets for continuity of supply to important points such as hospitals, radio stations, cinema houses and telephone exchanges.
Advantages (a) The design and layout of the plant are quite simple. (b) It occupies less space as the number and size of the auxiliaries is small. (c) It can be located at any place. (d) It can be started quickly and it can pickup load in a short time. (e) There are no standby losses. (f) It requires less quantity of water for cooling. (g) The overall cost is much less than that of steam power station of same capacity. (h) The thermal efficiency of the plant is higher than that of a steam power station. (i) It requires less operating staff Disadvantages (a) The plant has high running charges as the fuel (diesel) used is costly. (b) The plant doesn’t work satisfactorily under overload conditions for a longer period. (c) The plant can only generate small power. (d) The cost of lubrication is generally high. (e) The maintenances charges are generally high Objectives After studying this unit, you should be able to understand about diesel engine power plant, explain fuel injection system and its functions, and describe various injection schemes. Laxmi Institute of Technology, Sarigam (Mechanical Department)
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ASSIGNMENT TOPICS S. No.
TOPIC
1
Introduction
2
Fuel Air Cycles and Actual Cycles
3
Combustion
4
Fuels and its supply system for SI and CI engine
5
Ignition and Governing System
6
Supercharging
7
Combustion in SI and CI Engines
8
Engine Lubrication and Cooling
9
Measurement and Testing of IC engines
10
Engine Emission and their control
11
Application of diesel engines in power field
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Roll No.________
Enrollment No.________________Student sign:-_________ Gujarat Technological University
LAXMI INSTITUTE OF TECHNOLOGY, SARIGAM Academic year 2013-2014 Mid Semester Exam-II
Center Code: 086
B. E. – III (Sem – VI)
Branch: Mechanical Engineering
Subject: ICE
Subject Code: 2161902
Date: 17/03/2015 Time: 1:00 pm to 02:30 pm
Max. Marks: 30
Instructions: 1. Attempt all questions. 2. Make suitable assumptions wherever necessary. 3. Figures to the right indicate full marks.
Q.1
a) Explain with neat sketch Valve timing diagram for Diesel engine. Also explain de- [05] viation of an actual cycle from an ideal cycle. [05] b) State the name of Different types evaporative devices used in refrigeration system Explain Automatic expansion valve.
Q.2
a) State main applications of Refrigeration. Explain Ice making plant with a Suitable diagram. b) Briefly explain construction and working of Practical vapour absorption Refrigeration system. Also mention the advantages of this system.
[05]
a) Mention the limitations of Simple vapour compression refrigeration cycle. Briefly explain the working of Two stage compression with water intercooler and liquid sub cooler employed for vapour compression System. b) The atmospheric air at 300C dry bulb temperature and 75 % relative humidity enters a cooling coil at the rate of 200 m3/min. The coil dew point temperature is 140C and the by-pass factor of the coil is 0.1. Determine: 1. The temperature of air leaving the cooling coil; 2. The capacity of the cooling coil in tones of refrigeration 3. The sensible heat factor for the process.
[04]
a)what happens if R-22 or R-290 is used as a drop in substitute in R-12 refrigerator? b)With a notes on ‘ Total equivalent warming impact’. OR a) what are the advantages and disadvantages of multistage compression with intercooling in between the stages? b) A R-12 refrigeration system uses one compressor and three evaporators of capacities 20 TR,40 TR and 60 TR. All evaporators operate at a temperature of -10 0 c. Condenser temperature is 40 0 c . The liquid leaving the condenser is at 300c.the vapour at entry to compressor is dry-saturated and compression is isentropic find the compressor power and cop of the system.
[05] [05]
Q.2
Q.3
Q.3
[05]
[06]
[05] [05]
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2161903 Computer Aided Design
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(i) Course Content Teaching Scheme
Credits
L
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C
3
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2
5
Examination Marks Theory Marks PA (M) ESE (E) PA ALA 70 20 10
Practical Marks PA (V) PA (I) ESE OEP 30 0 20
Total Marks 150
UNIT-I 1. Fundamentals of Cad: Introduction, Reasons for implementing a CAD system, Computer Aided Process application, conventional design vs CAD. Benefits, Hardware, CAD softwares, Elements of Programming,CAD programming. Technical specification of CAD workstation, computer software-operating system UNIT-II 2. Computer Graphics: Scan conversions, DDA and Breshnham’s algorithm for generation of various figure, 2D and 3D transformations: Scaling, Translation, Rotation, Mirroring, Clipping, Homogeneous matrix.. UNIT-III 3. Geometrical Modeling: Types & mathematical representation of curves, wire frame models, entities, representations, parametric representations, Review of vector algebra, lines, circle, ellipse, parabolas, Parametric representation of synthetic curves, cubic curves, B spline, Bezier spline, sweep curves. Surfaces & solids – model, entities, representations, fundamentals of surface and solid modeling, B-rep, constructive solid geometry (CSG), analytical modeling, sweep. Solid manipulation, visual realism. Computer aided design of Mechanical Elements & Mechanical Assembly with animation. Capabilities of various commercially available software in the area of CAD. UNIT-IV 4. Graphics Standards: Standards for graphics programming, features of GKS, other graphics standards, PHIGS, IGES, PDES. Standards in CAD.
UNIT – V 5. Finite Element Analysis: Types of elements, types of error, derivation equitation finite element procedure, Stress – deflection – stiffness matrix, global matrix, conductivity table. Elimination approach, penalty approach, effect of temperature, principle of min. Potential energy, Mesh generation, Capability of different FEA software. Laxmi Institute of Technology, Sarigam (Mechanical Department)
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UNIT – VI 6. Optimization: Introduction, design synthesis, Engineering vs Optimum Design, Objectives of Optimization, Classification of Optimization problems and their procedure, techniques of optimization, Optimized design of machine components, Optimization Software.
(ii)Lecture Plan with References Subject Title: - Computer Aided Design
Session :- Dec-May 2015-16
Subject Code :- 2161903 Department :- Degree Engineering
Semester :- VIII Branch :– Mechanical Engineering
Lect. No.
Topics to be Covered Date of
1
UNIT 1 A typical product cycle, CAD tools for the design process of product cycle
2
CAD / CAM system evaluation criteria, Input / Output devices; Graphics
R2
3
Displays: Refresh display, DVST, Raster display, pixel value and lookup table
R2
4
Estimation of graphical memory, LCD, LED fundamentals.
R3
5
Concept of Coordinate Systems: Working Coordinate System,
R4
6
Model Coordinate System, Screen Coordinate System
R2
7
Line and Curve generation algorithm: DDA, Bresenham’s algorithms
R2
8
Graphics exchange standards and Database management system
R2
References
R2
UNIT 2 1
Parametric representation of lines: Locating a point on a line, parallel lines
R1
2
Perpendicular lines, distance of a point, Intersection of lines.
R1
3
Intersection of lines .Parametric representation of circle,
R1
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4
Ellipse, parabola and hyperbola
5
Synthetic Curves: Concept of continuity, Cubic Spline equation Properties and blending. Bezier Curve: equations Properties and advantages of B-Splines and NURBS. Various types of surfaces along with their typical applications.
6 7
R1 R1 R1 R1
UNIT 3 1
Geometry and Topology, Comparison of wireframe, surface and solid models,
R4
2
Properties of solid model, properties of representation schemes,
R4
3
Concept of Half-spaces
R1
4
Boolean operations. Schemes: B-rep, CSG, Sweep representation
R4
5
ASM, Primitive instancing
R4
6
Cell Decomposition and Octree encoding
R4
UNIT 4 1 2 3
Homogeneous representation; Translation, Scaling, Reflection, Rotation, Shearing in 2D and 3D; Orthographic and perspective projections Window to View-port transformation . UNIT 5
1
Review of stress-strain relation and generalized
2
Hooke's Law
3
Plane stress and Plane strain conditions
4
Concept of Total Potential Energy
5
Basic procedure for Solving a problem using Finite Element Analysis
R1 R1 R1
R4 R5 R5 R5 R4
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R4
6
1-D Analysis: Concept of Shape function and natural coordinates
7
Strain displacement matrix
8
derivation of stiffness matrix for structural problems
9
properties of stiffness matrix
R4
10
1-D structural problems
R4
11
elimination andpenalty approaches
R4
12
1-D thermal and fluid problems
R5
13
Trusses and Beams
R4
14
Formulation of stiffness matrix
R4
15
simple truss problems
R4
Simple truss problem to find displacement, reaction and stresses in truss members
R4
16 17
Structural analysis using Euler-Bernoulli beam element.
R5
Higher Order Element: CST element stiffness matrix formulation
R4
18 19
shape functions
20
Applications of Quad elements
21
Applications of axisymmetric elements
R4
R4 R5 R5
Abbreviations used in the reference column are explained at the end of the Lecture Plan. Reference Books: R1: Ibrahim Zied, CAD / CAM: Theory and Practice, McGraw-Hill R2: CAD/CAM and Automation by Farazdak Haideri R3: Hearn E J and Baker M P, Computer Graphics, Pearson R4: CAD/CAM: Theory and Concept by Kuldeep Sareen and Chandandeep Grewal R5: Logan D, A First Course in the Finite Element Method, Cengage. Laxmi Institute of Technology, Sarigam (Mechanical Department)
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PRACTICAL PLAN Subject Title :: Computer Aided Design
Session :: Dec-May 2015-16
Subject Code: 2161903 Department :: Degree Engineering
Semester : VI Branch: Mechanical Engineering
Sr. No. 1
List of Experiment
References
Prepare a programme for plotting lines and curves using algorithms learned.
2
Introductory exercise for 3-D modeling
3
Exercise for advanced 3-D modeling
4 Exercise for 3-D editing options
5
Exercise for Assembly modeling
6
Exercise for surface modeling
7
Introductory exercise for finite element analysis.
8
Exercise for FEA of 1-D structural problems
9
Exercise for FEA of trusses.
10
Exercise for FEA using Beam Element.
11
Exercise for FEA of 1-D thermal problems.
12
Exercise for FEA of 1-D fluid problems.
13
Exercise for FEA of 2-D structural problems.
All Demos will be explained during the lab session
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(iii) UNIT WISE (BLOW: UP) UNIT I INTRODUCTION
CAD or computer Aided Design can be defined as the use of computer to assist the user in design in system. It is a tool, which may be used to 1. Create 2. Modify 3. Analysis 4. Optimize the design All present day CAD systems are user-friendly and based on interactive computer graphics (ICG). Interactive Computer Graphics, as the name suggest, display data and information in the form of graphics is in a position to enter data in the form of commands which is readily converted by the software in to graphical form. Thus, the user can created drawing, modify them and explore further possibilities and options The design process: Before examining the several facts of computer aided design, let us first consider the general design process, the process of designing something is characterized by shigley as an interactive procedure, which consists of six identifiable steps or phases: 1. Recognition of need 2. Definition of problem 3. Synthesis 4. Analysis and optimization 5. Evaluation 6. Presentation Recognition of need involves the realization by something that a problem exists for which some corrective action should be taken. This might be the identification of some defect in a current machine design by an engineer or the perception of a new product marketing opportunities by a salesperson. Definition of problem involves a through specification of the item to be designed . This specification includes physical and functional characteristics, cost quality and operating performance.
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Synthesis and analysis are closely related and highly intensive in the design process. A certain component or subsystem of the overall system is conceptualized by the designer, subjected to analysis, improved through this analysis procedure and redesigned. The process is repeated until the design has been optimized within the constraints imposed on the designer. The components and subsystem are synthesized into the final overall system in a similar iterative manner. Evaluation is concerned with measuring the design against the specifications established in the problem definition phase. This evolution often requires the fabrication and testing of a prototype model to assess operating performance, quality. Reliability and other criteria. The final phase in the design process is the presentation of the design. This includes documentation of the design by means of drawing, material, specification, assembly lists and so on. Essentially the documentation requires that a design database be created. Figure illustrates the basics steps in the design process indicating its iterative nature
UNIT –II Simple geometric model may not require 3D illustrations and the models may be represented with only wire –frame entities or curves .the curve design or stick finger design represents the object in its simplest form .this is especially useful in representing 2D designs. Two Dimensional Geometric transformations The geometric transformation change the orientation, size, and shape of the objects this alter the coordinate description of objects the geometric transformation also used in animation the basic two dimension geometric transformation 1 Translation 2 Rotation 3scaling 4 reflection and 5 shear Coordinate Systems In CAD modeling system or global coordinate system or model coordinate system There are major types of coordinate system commonly used in CAD model 1 World coordinate system or model coordinate system (MCS) 2 User coordinate system (UCS) 3 Screen Coordinate system
UNIT III
Geometry and Topology Laxmi Institute of Technology, Sarigam (Mechanical Department)
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Geometry Geometry is the actual dimensions that define the entities of the object The geometry that define the object shoe in fig 1 the lengths of lines L1 ,L2, L3 2 the angle between the lines 3 the radius R of half circle 4 the center P1 of half circle
Topology Topology is the connectivity and associatively of the different entities of the object .it describes the way in which the different entities of the object are connected together 1 The line L1 shares a vertex with the line L2 and circle C1 2 The line L1 shares a vertex with the line L1 and L3 3 The line L3shares a vertex with the line L2 and circle C1 4 The line L1 and L3 do not overlap 5 the point P1 Lies outside the object It is the important to note that neither geometry nor topology alone can completely define the solid model the solid model needs both the geometrical and topological data Solid entities The solid model of an objective is created by using the three dimension gepometricentities know as object Evolution of A wireframe representation of an object is done using edges (lines curves) and vertices. Surface representation then is the logical evolution using faces (surfaces), edges and vertices. In this sequence of developments, the solid modeling uses topological information in addition to the geometrical information to represent the object unambiguously and completely Geometric Modeling
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UNIT IV In this chapter of Geometric Transformations various transformations such as Translation, Rotation, Shearing in 2D and 3D and Orthographic and Perspective projections are to be studied. By definition geometric transformation are mapping from one coordinate system onto itself. In other words the description of geometric model of the object can change within its own MCS. A geometric transformation is any bisection of a set having some geometric structure to itself or another such set. Specifically, "A geometric transformation is a function whose domain and range are sets of points. Most often the domain and range of a geometric transformation are both R2 or both R3. Often geometric transformations are required to be 1-1 functions, so that they have inverses." The study of geometry may be approached via the study of these transformations. Coordinate Systems In CAD three types of coordinate systems are needed in order to input, store and display model geometry and graphics. These are the Model Coordinate System (MCS), the World Coordinate System (WCS) and the Screen Coordinate System (SCS). Model Coordinate System The MCS is defined as the reference space of the model with respect to which all the model geometrical data is stored. The origin of MCS can be arbitrary chosen by the user. World Coordinate System As discussed above every object have its own MCS relative to which its geometrical data is stored. Incase of multiple objects in the same working space then there is need of a World Coordinate System which relates each MCS to each other with respect to the orientation of the WCS. It can be seen by the picture shown below. Screen Coordinate System In contrast to the MCS and WCS the Screen Coordinate System is defined as a two dimensional devicedependent coordinate system whose origin is usually located at the lower left corner of the graphics display as shown in the picture below. A transformation operation from MCS coordinates to SCS coordinates is performed by the software before displaying the model views and graphics. Viewing Transformations As discussed that the objects are modeled in WCS, before these object descriptions can be projected to the view plane, they must be transferred to viewing coordinate system. The view plane or the projection plane, is set up perpendicular to the viewing zv axis. The World coordinate positions in the scene are transformed to viewing coordinates, and then viewing coordinates are projected onto the view plane. The transformation sequence to align WCS with Viewing Coordinate System is. Laxmi Institute of Technology, Sarigam (Mechanical Department)
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1. Translate the view reference point to the origin of the world coordinate system. 2. Apply rotations to align xv, yv, and zv with the world xw, yw and zw axes, respectively.
UNIT V Finite element analysis is a powerful numerical technique for analysis. It is useful for solid machines, fluid mechanics, nuclear reactor etc. It is used for stress analysis in the area of solid mechanics. The basic concept of the finite element method is that a body or a structure may be divided into smaller elements of finite dimension called finite elements. The original body or the structure is considered as an assemblage of this elements connected at finite number of joints called nodes. The properties of the elements are formulated and combined to obtain the solution for the entire body or structure. For a given practical design problem, the engineer has to idealized the physical system into a finite element model with proper boundary condition and loads that are acting on the system. Then the discretization of a given body or structure into cell of finite element is performed and the mathematical model is analyzed for every element and for complete structure. The various unknown parameters are computed by using known parameters. Limitation of Finite Element Analysis: The finite element modeling of a given problem requires human expertise and knowledge. On the behavior of physical system and on various types of elements. Hence, it still remains as an art. Since finite element analysis method is an approximate numerical method the solution is not exact. The costs of FEA software packages are very high and it requires very costly computer hardware. If the number of elements are more at that time required for FEA is more. The main types of errors are: (a) mathematical modeling error, (b) Discretization error and (c) round off errors. 1. Mathematical modeling error: It is the error in the mathematical model which is taken into considerations. In the finite element analysis the mathematical model is assumed and the empirical constant are choose in the equation by solving the boundary conditions. This may lead to mathematical error in the modeling. 2. Discretization error: Discretization is a process of dividing the object into fine elements and these fine elements are spread over the complete object. In this process, the element is assumed and the elements are joined at nodal points and the whole object is considered to have been composed of large number of elements. There may be some error in the discretization of object. 3. Round off errors: The round off errors occurs due to the rounding of the decimal values. In the finite element analysis the matrices are generated by use of equation of the elements and these matrices are globalize and then are solved by using the digital computers. The accuracy of this calculation varies and because of which the calculation are rounded off to the nearest value which gets calculated and the final answer has minor errors because of the round off values Steps in Finite Element Analysis: 1) Discretization of the continuum by various finite elements: A taper beam subjected to an axial load P, can be discretized by modeling it as a series of finite elements each uniform but of different cress sectional. Laxmi Institute of Technology, Sarigam (Mechanical Department)
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Discretization
can
be
done
by
different
types
of
elements
as
described
above.
2) Selection of displacement model: The displacement model or the shape function maps the values of degree of freedom from the nodes to points within the element. This is important as the values of degree of freedom are calculated only at the nodes. The displacement model or shape function then gives the values at any point within the element. The simplest from of shape function is the linear displacement model. 3) Derivation of the element stiffness matrix: The element stiffness matrix relates the applied actions to the degrees of freedom in the element. For structural applications, we know that Force = Stiffness x Deflection. Action = Stiffness x Degree of freedom. {F} = [K] {U} Here, {F} represents the nodal forces; [K] represents the stiffness of each element (depending on the type of displacement model chosen) and {U} represents the displacement of each node. The matrix [K] is called the Element Stiffness Matrix. The element stiffness matrix can be derived by 3 methods: a) Energy Method: Here, we equate the work done by a force at the node to the strain energy stored in the element. b) Galerkin Method or Weighted Residual Method: This method consists of minimizing the sum or errors over the region of interest. This is done by attaching weightage to the error depending on its position. c) Castigliano’s Theorem: This method uses the principle that partial derivation of strain energy stored in the element with respect to force gives the deflection. d) Assemblage of the Algebraic Equations for the Overall Discretized Continuum: This process includes the assembly of overall or “Global Stiffness Matrix” for the entire body forms the individual stiffness matrices of all elements. Proper boundary conditions are then applies. e) Solutions for the Unknown Deflections: The algebraic equations assembled are then solved for unknown deflection. f) Computation of the Element Strains and Stresses from the Nodal Displacements.
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QUESTION BANK UNIT 1 1. What is CAD? 2. Distinguish between conventional design and computer aided design? 3. Discuss advantages & limitation of CAD. 4. List of hardware requirements for a CAD workstation. 5. List CAD software used commercially with their capabilities. 6. What is Computer Graphics? State general application of computer graphics. 7. Draw the flow chart and write Bresenham’s algorithm for generation of line. 8. Draw the flow chart and write Bresenham’s algorithm for generation of circle. 9. Explain DDA algorithm for generation of line. 10. 2D and 3D Transformations UNIT II
Geometric Modeling: Curves 1. Explain Geometrical Modelling. Explain wireframe modeling with its advantages and disadvantages. 2. 3. 4. 5.
Explain the non-parametric representation of curves. State its limitations. Explain the parametric representation of curves. What do you understand by analytic curves and synthetic curves? Explain the parametric equations for the following analytic curves: (i) Line, (ii) Circle, (iii) Ellipse, (iv) Parabola, (v) Hyperbola. (ii) State and explain the continuity conditions in synthetic curves. (iii)With neat sketch, explain Hermite cubic Spline curve.Obtain the Parametric equation for Hermite cubic spline curve. (iv) Why Bezier curve is preferred over Hermite cubic spline curve? With the neat sketch, explain the characteristics of Bezier curve. (v) With the neat sketch, explain the B-spline curve. State its advantages.
Geometric Modeling: Surfaces 1.What is geometric modeling? Explain its significance in CAD/CAM applications. 2. Explain the different methods of geometric modeling. State their advantages and limitations. 3. What do you understand by 2D, 2 and 1/2D and 3D wire-frame models? 4. What do you understand by parametric and non-parametric representation of surfaces? 5. Explain the following entities used in surface modeling: (i) Plane surface, (ii) Ruled surface, (iii) Tabulated surface, (iv) Surface of revolution, (iii) Tabulated surface, (iv) Surface of revolution, (vii) Coons patch, (viii) Fillet surface, (ix) Offset surface. Laxmi Institute of Technology, Sarigam (Mechanical Department)
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UNIT III 1. What do you understand by geometry and topology in solid modeling? 2. What are the commonly used primitives in solid modeling? 3. What do you understand by C-rep and B-rep approaches? Compare them. 4. With neat sketches, explain the various Boolean operations used in CSG solid modeling. 5.What are the various types of sweeps used in solid modeling?
UNIT IV 1. Discuss translation and rotation with example. 2. Write the transformation matrices for rotation, translation and scaling. 3. What is composite matrix? Derive the composite transformation matrix for the object is mirrored about arbitrary line. 4. Show that the composition of two rotations is additive by concatenating the matrix representations for R (θ1) and R (θ2) to obtain R (θ1) R (θ2) = R (θ1 + θ2 ) 5. Explain scaling of a line about any other point with suitable example. (SS Khandare Page No 62) 6. consider a triangle ABC having coordinates A (5, 5), B (8, 5) and C (5, 10).Determine new vertex positions if (1)The triangle is rotated by 60 degrees anticlockwise about vertex A (2)The triangle scaled by 2 times in x direction and 3 times in y direction about vertex A (3)If it is mirror @ a line Y=2X+4.
UNIT V 1. 2. 3. 4. 5.
Define Finite element analysis? Explain Types of elements used in F.E.A. Explain Types of Error? Explain Finite Element Procedure. Derive the stiffness matrix for Two dimensional Element. Explain Global stiffness matrix.
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(vi) MODEL QUESTION PAPER Roll No.________
Enrollment No.____________Student sign:-_________
Gujarat Technological University LAXMI INSTITUTE OF TECHNOLOGY, SARIGAM Academic year 2012-2013 Center Code: 086
Mid Semester Exam- I B. E. – III (Sem – VI)
Branch: Mechanical Engineering
Subject: Computer Aided Design Date: 25/03/2012
Time: 11.30 am to 1:00 pm
Subject Code: 161903 Max. Marks: 30
Instructions: 1. Attempt all questions. 2. Make suitable assumptions wherever necessary. 3. Figures to the right indicate full marks.
Q.1
Q.2
a) A triangle PQR with vertices P(0,0), Q(4,0) and R(2,3) is to be subjected to following two transformations in order: 1. Translation through 4 and 2 units along X and Y directions respectively, and 2. Rotation through 90° in counterclockwise direction about the new position of point R. Determine new position of Triangle. b) Explain any one type of display device.
[07]
a) Explain Bresenham’s Line Algorithm. b) Draw a diagram showing product cycle with the implementation of CAD.
[07]
[03]
[03]
OR Q.2
a) Explain DDA algorithm for generation of line.
[07]
b) Explain reasons for implementing CAD.
[03]
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Q.3
a) Generate an ellipse with semi major axis a=5 and semi minor axis b=2 inclined at 45° to the horizontal with center at (2,2). b) Describe the structure of an IGES file.
[07]
[03]
OR Q.3
a) A triangle ABC with vertices A(40,30), B(100,30) and C(40,90) is to be scaled by a factor of 0.5 about a point (60,50). Determine the co ordinates of the vertices for a scaled triangle.
[07]
b) Describe the structure of an PDES file. [03]
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Industrial Engineering (2161907)
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(i) Course Content Category of Course
Course Title Course Theory Paper Course
Course Code
ME VI SEM
Industrial Engineering
2161907
L
T
P
3
0
2
Theory Paper Max.Marks:70 Min. Marks:23 Duration :2:30 hours
UNIT:ILocation Selection and Plant Layout: Nature of Location Decision, Importance of Plant Location, Dynamic Nature of Plant Location, Choice of site for selection, Comparison of location, Principles of Plant layout and Types, factors affecting layout, methods, factors governing flow pattern, travel chart, analytical tools of plant layout, layout of manufacturing shop floor, repair shop, services sectors and process plant. Quantitative methods of Plant layout: CRAFT and CORELAP, Relationship diagrams.
UNIT :II Production Planning and Control: Types of Production systems and their Characteristics, functions and objectives of Production Planning and Control, Sales forecasting: Techniques and Applications, Steps of Production Planning and Control: Process planning, Leading, Scheduling, Dispatching and Expediting with illustrative examples, Introduction to line of balance, assembly line balancing, and progress control
.
UNIT:III Productivity and Work Study: Definition of productivity, application and advantages of productivity improvement tools, reasons for increase and decreases in productivity. Areas of application of work study in industry. Reaction of management and labour to work study. Method Study: Objectives and procedure for methods analysis, Recording techniques, Operations Process Chart, Flow Process Chart, Man-Machine , Multiple Activity Chart, Travel Chart, and Two Handed process chart, String Diagram, Therbligs, Micro motion and macro-motion study: Principles of motion economy, Normal work areas and work place design. Work Measurement: Objectives, Work measurement techniques – time study, work sampling, pre-determined motion time standards (PMTS) Determination of time standards. Observed time, basic time, normal time, rating factors, allowances, and standard time. Introduction to ergonomics.
UNIT IV: Job Evaluation and Wage Plan: Objective, Methods of job evaluation, job evaluation procedure, merit rating (Performance appraisal), method of merit rating, wage and wage incentive plans.
UNIT V: Industrial Legislation: Need for Industrial legislation, Factories act 1948, Industrial dispute act 1947, The Indian trade unions act 1926, Industrial employment act 1946, Payment of wage act 1936, Workmen compensation act 1923, Payment of bonus act 1965, Employees provident fund scheme 1952.
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UNIT VI: Inspection and Statistical Quality Control: Inspection – functions, types, objectives and benefits, quality control principles, Concepts of quality circles, Total quality management, Quality assurance, Quality audit, Basic Concept ISO 9000, ISO 14000 and QS 9000, Six sigma: Concept, Principle, Methodology, Scope, Advantage and limitations. SQC Concept, variable and attributes, normal distribution curves and its property charts for variable and attributes and their applications and interpretation (analysis) process capability. Acceptance sampling, sampling plans, OC curves and AOQ curves.
UNIT VII: Entrepreneurship: Concept, product identification, infrastructure facilities, preparation of project report, sources of industrial finance, Resources allocation, Government incentives to entrepreneurs.
(ii)Lecture Plan with References Subject Title: -Industrial Engineering
Session :-Dec-May 2014
Subject Code :- 2161907 Department :- Mechanical Engineering
Semester :- VI
Lect. No.
Branch :– Mechanical Engineering
Topics to be Covered Date of
References
UNIT 1 Nature of Location Decision, Importance of Plant Location
1
Dynamic Nature of Plant Location, Choice of site for selection, Comparison of location, Principles of Plant layout and Types, factors affecting layout, methods, factors governing flow pattern
2 3 4
travel chart, analytical tools of plant layout,
5
layout of manufacturing shop floor,
6
Repair shop, services sectors and process plant.
7 8
Repair shop, services sectors and process plant. CORELAP, Relationship diagrams. UNIT 2 Laxmi Institute of Technology, Sarigam (Mechanical Department)
63
Types of Production systems and their Characteristics functions and objectives of Production Planning and Control,
9 10 11
forecasting: Techniques and Applications, Steps of Production Planning and Control: Process planning
12 13 14 15 16
Leading, Scheduling, Dispatching Expediting with illustrative examples, Introduction to line of balance, Assembly line balancing, and progress control. UNIT 3 Definition of productivity, application and advantages of productivity improvement tools,
17
Reasons for increase and decreases in productivity. Areas of application of work study in industry
18
Reaction of management and labour to work study.
19
Method Study: Objectives and procedure for methods analysis
20
Recording techniques, Operations Process Chart,
21
Flow Process Chart, Man-Machine , Multiple Activity Chart, Travel Chart,
22
Two Handed process chart, String Diagram, Therbligs,
23 24
Micro motion and macro-motion study: Principles UNIT 4
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25 26 27 28 29
Objective, Methods of job evaluation job evaluation procedure merit rating (Performance appraisal), method of merit rating Wage and wage incentive plans. UNIT 5
30
Need for Industrial legislation, Factories act 1948 Industrial dispute act 1947, The Indian trade unions act 1926,
31
Industrial employment act 1946, Payment of wage act 1936
32
Workmen compensation act 1923, Payment of bonus act 1965,
33 34
Employees provident fund scheme 1952. UNIT 6 Inspection – functions, types, objectives and benefits, quality control principles
35
Concepts of quality circles, Total quality management, Quality assurance,
36
Quality audit, Basic Concept ISO 9000, ISO 14000 and QS 9000
37
Six sigma: Concept, Principle, Methodology, Scope, Advantage and limitations.
38 39
SQC Concept, variable and attributes normal distribution curves and its property charts for variable
40
attributes and their applications and interpretation (analysis) process capability
41
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Acceptance sampling, sampling plans, OC curves and AOQ curves.
42
UNIT 7 Concept, product identification, infrastructure facilities
43
preparation of project report, sources of industrial finance,
44 45
Resources allocation, Government incentives to entrepreneurs
Abbreviations used in the reference column are explained at the end of the Lecture Plan. Reference Books:
R1: Industrial Engineering and Production Management Martand Telsang S Chand & company. R2: Industrial Engineering and Production Management by Banga and Sharma, Khanna Publishers. R3: Industrial Engineering and Management by Dr. B. Kumar Khanna Publishers
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(iii)
UNIT WISE (BLOW: UP) UNIT I
Location Selection and Plant Layout: Plant location is an important decision which decides the fate of the business. In the past, much importance was not given to the selection of appropriate location and the decisions in this regards were mainly governed by the individual preferences of the entrepreneurs and social customs. This resulted in failure of many organization. In this chapter nature of locations for business. Plant layout and site selection major things in it. Also, first phase means site selection to final phase when final completion for site with proper layout.
UNIT –II Production Planning and Control: For any final product first thing was to decide or scheduling of process or proper planning needed. Without any planning big mistakes comes in final product and schedule. That’s why proper planning was needed. For product planning sales forecasting needed. Sales forecasting means the task of projecting the futures sales of the firm. It indicates how much of a product is likely to be sold during a specified periods in a specified market, at specified prices.
UNIT III Productivity and Work Study: Productivity is the ratiobetween output and input. It is quantitative relationship between what we produce and what we have spent to produce. Productivity is nothing but reduction in wastage of resources like men, material, machine, time, space, capital etc. It can be expressed as human efforts to produce more and more with less and less inputs of resources so that there will be maximum distribution of benefits among maximum number of people. Productivity denotes relationship between output and one or all associated inputs. European Productivity is an attitude of mind. It is a mentality of progress of the constant improvement of that which exists. It is certainty of being able to do better than yesterday and continuously. It is constant adoption of economic and social life to changing conditions. It is continual effort to apply new techniques and methods. It is faith in human progress‟. In the words of Peter Drucker productivity means a balance between all factors of production that will give the maximum output with the smallest effort.
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UNIT IV Job Evaluation and Wage Plan Job evaluations the rating of jobs according to a specifically planned procedure in order to determine the relative size and worth of each job. Itexamines the contents and requirements of jobs and measures these against a standard scale. This result in job grades, scores, levels or ratings whereby jobs can be compared with other jobsto determine their relative worth. Wages is factor affecting the relations between the management and the workers. Wages is the remuneration paid for the services renders by the workers. .
UNIT V Industrial Legislation Industrial legislation are the laws enacted by the government to provide economics and social justice to the workers in industries. These laws provides guidelines to the industrialists in dealing with the matters of wages, incentives, facilities and other working condition of workers. Legislation looks after the general labour problems like social welfare, insurance and industrial dispute, while specific legislation looks after the work of specific industries, transport, mines, electricity, waste disposal, boiler etc. Laxmi Institute of Technology, Sarigam (Mechanical Department)
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There are different acts are as below: 1) Factories act 1948 2) Industrial dispute act 1947 3) The Indian trade unions act 1926 4) Industrial employment act 1946, 5) Payment of wage act 1936, 6) Workmen compensation act 1923, 7) Payment of bonus act 1965, 8) Employees provident fund scheme 1952.
UNIT VI Inspection and Statistical Quality Control Inspection is the most common method of attaining standardization, uniformity and quality of workmanship. It is the cost art of controlling the product quality aftercomparison with the established standards and specifications. It is the function of qualitycontrol. If the said item does not fall within the zone of acceptability it will be rejected andcorrective measure will be applied to see that the items in future conform to specified standards.Inspection is an indispensable tool of modern manufacturing process. It helps toquality, reduces manufacturing costs, eliminate scrap losses and assignable causesof defective work. Quality control can be defined as that Industrial Management technique by meansof which product of uniform acceptable quality is manufactured. Total Quality Control defined as an effective system for integrating the qualitydevelopment, quality maintenance and quality improvement efforts of the various groups in an organization so as to enable production and service at the most economical levelwhich allow for full customer satisfaction.
UNIT VII Entrepreneurship Entrepreneurship is the attempt to create value through recognition of businessopportunity, the management of risk taking appropriate to the opportunity andthrough the communicative and management skills to mobilize human, financialand material resources necessary to bring a project to fruition.
Relationships between entrepreneur and entrepreneurship
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QUESTION BANK SR NO 1
UNIT:1LOCATION SELECTION AND PLANT LAYOUT Define plant layout. Discuss types of plant layout. With suitable example
3
Discuss the factors to be considers for the selection of the site for thermal power plant. Which are the major factors affecting plant layout
4
Differentiate – process layout pan v/s product layout plan
2
5 6 7 8
1
2
3
4 5 6 7 8 9 10
Principle of good plant layout In order to achieve sound plant layout, explain in detail the scientific step by step procedure that must be followed. List the factors which should be considered for the selection of the site for automobile industry. Write various types of plant layout and explain any two with near sketch. UNIT:2PRODUCTION PLANNING AND CONTROL What is P.P.C.? give the major objective of the same Forecast the demand for the following series by exponential smoothing method (take α = 0.3). Period 1 2 3 4 5 6 7 8 9 10 Actual 10 12 08 11 09 10 15 14 16 15 Demand The process time for five jobs and due date (days) of the jobs are given in the following table: Job 1 2 3 4 5 Process Time (days) 3 6 9 5 7 Due date (days) 6 20 30 12 2
YEAR May-2012, Nov-2011, Dec-2013
Nov-2011 May-2012, Nov-2014 May-2012, Jan-2013 May- 2013 May 2013 Dec-2013 Nov-2014
May-2014
May-2011
May-2014
Job may be sequence according to following rules: 1) Minimum process time 2) First come first serve 3) Due date (days) The sale of drilling machines during the last six years is as under. Forecast the sales in the year 2012 using suitable method. Nov-2011 Year 2006 2007 2008 2009 2010 2011 Units sold 10 15 19 22 24 25 Explain the role of PPC in engineering industry. Nov-2011 Effective PPC guarantees better utilization of the available resources – Nov-2011 discuss giving suitable example. Write the function included under the activity of production planning. May-2012 What is economic order quantity? May-2012 Discuss the following method of sales forecasting May-2012, 1) Exponential smoothing May-2014 2) Method of weighted moving average. What is line balancing? Discuss in detail assembly line balancing taking May-2012, suitable example. MayLaxmi Institute of Technology, Sarigam (Mechanical Department)
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11 12 13 14 15 16 17
Explain in detail method of weighted moving average. What is MRP? Explain steps involved in MRP programme. Discuss the method of job sequencing to minimize the machine ideal time. Which are the main functions of production planning and control department? Discuss – standardization and simplification. Write function included under the activity of production planning. Discuss different method of sales forecasting
2014,Nov2014 May2014, Jan-2013 May2013 Dec- 2013 Dec- 2013 Dec- 2013 May-2014 Nov-2014
UNIT:3 PRODUCTIVITY AND WORK STUDY 1 2 3 4
5
6 7
8
9 10 11
12
13 14 15 16
What is Productivity? Give various ways to improve productivity and alsoExplain at least one way, with the help of suitable example Define Method Study and explain technique with its various steps? What is Work measurement? List the various techniques of work Measurement and also explain how the Standard time is calculated. Differentiate between Micro & Macro motion study. Explain in brief variousTechniques for micro motion study. Write a note on (Any Two) 1. Flow process chart 2. String Diagram 3. Two handed process chart State the relationship between productivity and work study. Explain Various tools for increasing productivity. State the relationship between cumulative timing and fly back timing. How standard time is calculated? Wrote briefly on (1) work flow diagram (2) operation process chart (3) machine data cards What is method study? Explain in brief various charts and diagrams Utilized in method study. What is therblig? State the importance of micro motion study What is Productivity? Discuss the factors affecting the productivity of themanufacturing organization. Discuss the following: (i) Work Study and Management. (ii) Work Study and the Worker. Discuss the following: (i) Ineffective time within the control of the worker. (ii) Ineffective time due to shortcomings on the part of management. Define Method Study. Discuss the objectives of method study. Explain in brief operation process charts and machine data cards Explain Economic order quantity
May-2011, May-2012 May-2011, Nov- 2014 May-2011 May-2011
May-2011
May-2011 May-2011, Jan- 2013, May-2014 May-2012, May-2014 May-2012, May-2014 May-2012, May-2014 May-2011, May-2014, Nov-2014 Nov-2011
Nov-2011 Nov-2011 Jan-2013 Jan-2013
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17
18 19 20 21 22 23 24 25
Define the following: 1) Productivity 2) Productivity Index 3) Work study 4) Ergonomics Explain the following in connection with time study. (i) Selecting the job. (ii) Breaking the job into elements. State the objectives of work measurement. Name the work measurement Techniques. Explain in brief the normal work area and work place design. Describe the effects of the following on the productivity. (i) Plant layout. (ii) Working conditions. Describe the ways to increase the industrial productivity. Explain principle of motion economy and work place layout. How does the multiple activity charts help to reduce the ideal time of men and machine? Discuss – string diagram and its uses.
May- 2013
Dec-2013 Dec-2013 Dec-2013 Dec-2013 Dec-2013 Nov-2014 Nov-2014 Nov-2014
UNIT:4 JOB EVALUTION AND WAGE PLAN Define wages and explain in detail various types of incentives. 1 2 3 4 5 6 7 8
State various methods of job evaluation, discuss in brief. Incentives are necessary for smooth and the efficient running of the Manufacturing organization. – Discuss giving suitable example. Define wages and explain in detail various types of incentives. State various methods of job evaluation. Differentiate Minimum Wage, Fair Wage and Living Wage. Describe the characteristics of good wage plan. Discuss any one wage plan. What is job evaluation? Discuss any one method of job evaluation.
May-2011, May-2012, May-2014, May-2014 May-2012 Nov-2012 Jan-2013 Jan-2013, May-2014 May-2013 Dec-2013 Dec-2013, May-2014
UNIT:5 INDUSTRIAL LEGISLATION What are factories Act? As per the factories act 1948 what are the major Provisions for safety and Health? 1
2 3 4 5
What is industrial dispute? Discuss the process of resolving the industrial Disputes through the Industrial Dispute Act. Explain the workman’s compensation Act, 1923. What is industrial legislation? Name the different acts which are helpful inresolving the industrial disputes. Discuss any one act in detail. What are the different provisions made under various Indian trade union acts?
May-2011, May-2012, Jan-2013, May-2013, May-2014, Nov-2011 May-2013 Dec-2013 Nov-2014
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UNIT:6 INSPECTION AND STATISTICAL QUALITY CONTROL 1
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
What is term S.Q.C.? Explain operating characteristic curves for acceptancesampling. Define following terms 1. Quality, 2. Quality control, 3. Quality assurance, 4. Reliability, 5. Quality audit, 6. Inspection, 7. T.Q.M. State the advantages of S. Q. C. what attribute and variable quality Characteristics are? Explain following terms (1) quality assurance, (2) quality and inspection, (3) T. Q. M. Explain in detail how P chart and C chart are constructed? State the important objectives of Quality Control. Which duties are Generally assigned to the Quality Control Department? What is the purpose of control charts? Explain how this purpose is Achieved in manufacturing? What is an OC curve? Explain the step-by-step procedure for the Construction of an OC curve. Explain the following in brief: 1) The OC curve 2) Control chart for the number of defects Discuss the functions of inspection department in a manufacturing plant. What is quality control? State important objectives of statistical quality control. Discuss – Total Quality Management. How is the OC curve prepared? Define the control chart. Discuss the control charts for variables. Discuss – Sampling Plans. State the advantages of S.Q.C. What are attribute and variable quality characteristics? Explain operating characteristics curves for acceptance sampling.
May-2011, May-2014, Nov-2014 May-2011 May-2012 May-2012, May-2014 May-2012, May-2014 Nov-2011 Nov-2011 Nov-2011 May-2013 Dec-2013 Dec-2013 Dec-2013 Dec-2013 Dec-2013 Dec-2013 May-2014 May-2014
UNIT:7 ENTERPRENEURSHIP 1 2
What is entrepreneur and explain his major characteristics. State various sources of industrial finance. State various government incentives to entrepreneurs.
3
4 5 6 7
State various sources of industrial finance. State various government incentives to Entrepreneurs. Discuss in brief: factor affecting entrepreneurial growth. Define the term entrepreneur and entrepreneurship & differentiate them. List out the obstacles in the way of entrepreneur’s development.
May-2011, Nov-2014 May-2012, Nov-2011 May-2012, Dec-2011, May-2014 Jan-2013, May-2014 May-2013 May-2013 May-2013
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(vi) MODEL QUESTION PAPER
Seat No.: _____
Enrolment No.______
GUJARAT TECHNOLOGICAL UNIVERSITY BE- VIth SEMESTER–EXAMINATION – MAY- 2012
Subject code: 161907 Subject Name: Industrial Engineering Time: 10:30 am – 01:00 pm
Date: 24/05/2012 Total Marks: 70
Instructions: 1. Attempt all questions. 2. Make suitable assumptions wherever necessary. 3. Figures to the right indicate full marks.
Q.1 (a) Define plant lay out. discuss following types of plant layout (1) Process layout (2) Group technology (3) Fixed position layout (b) Wrote briefly on (1) Work flow diagram (2) Operation process chart (3) Machine data cards
07
07
Q.2 (a) Write the functions included under the activity of production planning. 04 (b) What is economic order quantity? 03 (c) Discuss the following methods of sales forecasting 07 (1) Exponential smoothing (2) Methods of weighted moving average OR (c) What is line of balancing? discuss in detail assembly line balancing 07 taking suitable example Q.3
Q.3
Q.4
Q.4
Q.5
(a) What are factories act? What are major provisions for safety and health? (b) State various sources of industrial finance. (c) State various government incentives to entrepreneurs. OR (a) State various methods of job evaluation, discuss in brief. (b) Define wages and explain in detail various types of incentives.
07 04 03 07 07
(a) State the relationship between productivity and work study. Explain 07 Various tools for increasing productivity. (b) State the relationship between cumulative timing and fly back timing. 07 How standard time is calculated? OR (a) What is method study? Explain in brief various charts and diagrams 07 Utilized in method study. (b) What is therblig? State the importance of micro motion study. 07 (a) State the advantages of S. Q. C. what attribute and variable quality Characteristics are.
07
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(b) Find UCL and LCL for following data Sample no.
1 2 3 4 5 6 7 8 9 10
07
--X
R
26.0 34.0 28.5 32.75 29.25 29.25 26.0 24.75 27.25 30.25
35 17 18 22 31 15 19 29 18 9
Take A2=0.73, D3=0, D4=2.28,d2=2.059 OR Q.5 (a) Explain following terms (1) quality assurance (2) quality and inspection (3) T. Q. M. (b) Explain in detail how P chart and C chart are constructed ?
07
07
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181901 Refrigeration and Air-conditioning
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(i) Course Content UNIT 1 Introduction: Brief history and need of refrigeration and air conditioning, methods of producing cooling, ton of refrigeration, coefficient of performance, types and application of refrigeration and air condensing systems.
UNIT 2 Refrigerants: Classification, nomenclature, desirable properties, secondary refrigerants, future industrial refrigerants UNIT 3 Air refrigeration: Reversed Carnot cycle and its limitation, Bell-Coleman cycle, aircraft refrigeration, working and analysis of Simple; Bootstrap; Reduced ambient and Regenerative air refrigeration systems UNIT 4 Vapour Compression system: Simple system on P-h and T-s diagrams, analysis of the simple cycle, factors affecting the performance of the cycle, actual cycle Compound Compression System: Compound compression with intercooler, flash gas removal and flash intercooler, multiple evaporators with back pressure valves and with multiple expansion valves without flash inter cooling, analysis of two evaporators with flash intercooler and individual expansion valve and multiple expansion valve, cascade refrigeration system UNIT 5 Absorption refrigeration system: Desirable characteristics of refrigerant, selection of pair, practical H2O -NH3 cycle, LiBr – H2O system and its working, h-x diagram and simple calculation of various process like adiabatic mixing and mixing with heat transfer, throttling, Electrolux refrigeration system* UNIT 6 Refrigeration system components: Types; construction; working; comparison and selection of compressors*; condensers; expansion devices; and evaporators, refrigeration piping accessories*, evacuation and charging of refrigerant*, properties and classification of thermal insulation
UNIT 7 Psychrometry: Dalton’s law of partial pressure, Properties of moist air, temperature and humidity measuring instruments, psychrometric chart, psychrometric processes such as sensible heating and cooling, heating and humidification cooling and dehumidification, chemical dehumidification, adiabatic saturation UNIT 8 Human comfort: Selection of inside design conditions, thermal comfort, heat balance equation for a human being, factors affecting thermal comfort, Effective temperature, comfort chart and factors governing effective temperature, selection of outside design conditions UNIT 9 Load analysis: Site survey, outdoor and indoor design conditions, classification of loads, flywheel effect of building material and its use in design, effect of wall construction on cooling load, instantaneous heat gain (IHG) and instantaneous cooling load (ICL) heat transmission through sunlit and shaded glass using tables, method of reduction of solar heat gain through glass, calculations of cooling load TETD due to Laxmi Institute of Technology, Sarigam (Mechanical Department)
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sunlit and shaded roof and walls using tables, ventilation and air infiltration, load due to outside air, heat gain from occupants; electric lights; product; electric motor and appliances, load calculations for automobiles, use of load estimation sheet*, introduction of CLTD method UNIT 10 Duct design and air distribution: Function; classification and economic factors influencing duct layout, equal friction method of duct design, use of friction chart, dynamic losses and its determination, Requirements of air distribution system, air distribution, grills, outlets, application, location UNIT 11 Air-conditioning systems: Classification, system components, all air; all water; and air-water systems, room air conditioners, packaged air conditioning plant, central air conditioning systems, split air conditioning systems
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(i)
Course Content
(ii)Lecture Plan with References Subject Title: RAC
Session :- Dec –May 2016
Subject Code :- 181901
Semester :- 8th
Department :-Mechanical Engineering
Branch :– Mechanical Engineering
Lect. No.
Topics to be Covered Date of
References
UNIT 1 1 2 3
Brief history and need of refrigeration and air conditioning methods of producing cooling, ton of refrigeration, coefficient of performance types and application of refrigeration and air condensing systems.
R-1
UNIT 2
R-1 R-1
4
Classification, nomenclature
5
desirable properties, secondary refrigerants, future industrial refrigerants
R-1 R-1
R-1
UNIT 3 6
Reversed Carnot cycle and its limitation, BellColeman cycle,
R-1
7
aircraft refrigeration, working and analysis of Simple; Bootstrap
R-1
8
Reduced ambient and Regenerative air refrigeration systems
R-1
UNIT 4 9
Simple system on P-h and T-s diagrams, analysis of the simple cycle
R-1
10
factors affecting the performance of the cycle, actual cycle
R-1
11
Compound compression with intercooler, flash gas removal and flash intercooler
R-1
12
multiple evaporators with back pressure valves and with multiple expansion valves without flash inter cooling
R-1
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analysis of two evaporators with flash intercooler and individual expansion valve and multiple expansion valve, cascade refrigeration system
R-3
UNIT 5 15
Desirable characteristics of refrigerant, selection of pair, practical H2O -NH3 cycle
R-3
16
LiBr – H2O system and its working, h-x diagram and simple calculation of various process like adiabatic mixing and mixing with heat transfer
R-3
17
throttling, Electrolux refrigeration system
R-3
18
UNIT 6 Types; construction; working; comparison and selection of compressors
R-3
19
condensers; expansion devices; and evaporators, refrigeration piping accessories
R-3
20
evacuation and charging of refrigerant*, properties and classification of thermal insulation
R-3
21
UNIT 7 Dalton’s law of partial pressure, Properties of moist air, temperature and humidity measuring instruments
R-3
22
psychrometric chart, psychrometric processes such as sensible heating and cooling
R-3
23
heating and humidification cooling and dehumidification, chemical dehumidification, adiabatic saturation
R-3
UNIT 8 24
Selection of inside design conditions, thermal comfort, heat balance equation for a human being
R-5
25
factors affecting thermal comfort, Effective temperature, comfort chart and factors governing effective temperature
R-5
26
selection of outside design conditions
R-5
27
UNIT 9 Site survey, outdoor and indoor design conditions,
R-5
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classification of loads, flywheel effect of building material and its use in design, effect of wall construction on cooling load 28
instantaneous heat gain (IHG) and instantaneous cooling load (ICL) heat transmission through sunlit and shaded glass using tables, method of reduction of solar heat gain through glass
R-5
29
calculations of cooling load TETD due to sunlit and shaded roof and walls using tables, ventilation and air infiltration
R-5
30
31 32
34 35
UNIT 10 Function; classification and economic factors influencing duct layout equal friction method of duct design, use of friction chart, dynamic losses and its determination Requirements of air distribution system, air distribution, grills, outlets, application, location UNIT 11 Classification, system components, all air; all water; and air-water systems, room air conditioners packaged air conditioning plant, central air conditioning systems, split air conditioning systems
R-3
R-5 R-5
R-5 R-5
Abbreviations used in the reference column are explained at the end of the Lecture Plan. Reference Books: R1: Refrigeration and Air Conditioning by C P Arora, McGraw-Hill India Publishing Ltd. R2: Refrigeration and Air-conditioning by Ramesh Arora , Prentice Hall of India R3: Refrigeration and Air Conditioning by Manohar Prasad, New Age International Publisher R4: Refrigeration and Air Conditioning by Ameen Ahmadul, PHI India R5: Refrigeration and Air Conditioning by Jordon and Prister, Prentice Hall of India Pvt. Ltd
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82 (iii) UNIT WISE (BLOW: UP) UNIT I
Introduction Understand the basic concepts of refrigeration and air conditioning systems: Refrigeration may be defined as the process of achieving and maintaining a temperature below that of the surroundings, the aim being to cool some product or space to the required temperature. One of the most important applications of refrigeration has been the preservation of perishable food products by storing them at low temperatures. Refrigeration systems are also used extensively for providing thermal comfort to human beings by means of air conditioning. Air Conditioning refers to the treatment of air so as to simultaneously control its temperature, moisture content, cleanliness, odour and circulation, as required by occupants, a process, or products in the space. The subject of refrigeration and air conditioning has evolved out of human need for food and comfort, and its history dates back to centuries. The history of refrigeration is very interesting since every aspect of it, the availability of refrigerants, the prime movers and the developments in compressors and the methods of refrigeration all are a part of it. The French scientist Roger ThÝvenot has written an excellent book on the history of refrigeration throughout the world UNIT –II
Refrigerants Get the basic idea about the Refrigerants: A refrigerant is a substance or mixture, usually a fluid, used in a heat pump and refrigeration cycle. In most cycles it undergoes phase transitions from a liquid to a gas and back again. Many working fluids have been used for such purposes. Fluorocarbons, especially chlorofluorocarbons, became commonplace in the 20th century, but they are being phased out because of their ozone depletion effects. Other common refrigerants used in various applications are ammonia, sulfur dioxide, and non-halogenated hydrocarbons such as propane UNIT III Vapour Compression system & Compound Compression System
Understand and analysis of various refrigeration cycles: Vapor-compression refrigeration,[1] in which the refrigerant undergoes phase changes, is one of the many refrigeration cycles and is the most widely used method for air-conditioning of buildings and automobiles. It is also used in domestic and commercial refrigerators, large-scale warehouses for chilled or frozen storage of foods and meats, refrigerated trucks and railroad cars, and a host of other commercial and industrial services. Oil refineries, petrochemical and chemical processing plants, and natural gas processing plants are among the many types of industrial plants that often utilize large vapor-compression refrigeration systems. UNIT IV Absorption refrigeration system Get the basic idea about the Refrigerants: An absorption refrigerator is a refrigerator that uses a heat source (e.g., solar energy, a fossil-fueled flame, waste heat from factories, or district heating systems) which provides the energy needed to drive the cooling process. Absorption refrigerators are often used for food storage in recreational vehicles. The principle can also be used to aircondition buildings using the waste heat from a gas turbine or water heater. Using waste heat from a gas turbine makes the turbine very efficient because it first produces electricity, then hot water, and finally, air-conditioning (called cogeneration/trigeneration). UNIT V Refrigeration system components:
Get the basic idea about the Refrigeration components: Refrigeration has had a large impact on industry, lifestyle, agriculture and settlement patterns. The idea of preserving food dates back to the ancient Roman and Chinese empires. However, refrigeration technology has rapidly evolved in the last century, from ice harvesting to temperature-controlled rail cars. The introduction of refrigerated rail cars contributed to the westward expansion of the United States, allowing settlement in areas that were not on main transport channels such as rivers, harbors, or valley trails. Settlements were also developing in infertile parts of the country, filled with new natural resources. These new settlement patterns sparked the building of large cities which are able to thrive in areas that were otherwise thought to be inhospitable, such as Houston, Texas and Las Vegas, Nevada. In most developed countries, cities are heavily dependent upon refrigeration in supermarkets, in order to obtain their food for daily consumption.
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UNIT VI Psychrometry Make basic calculation of psychometric properties and process: Psychrometrics or psychrometry or hygrometry are terms used to describe the field of engineering concerned with the determination of physical and thermodynamic properties of gas-vapor mixtures. The term derives from the Greek psuchron (ψυχρόν) meaning "cold"[1] and metron (μέτρον) meaning "means of measurement" UNIT VII Human comfort
Get the basic idea about the Human comfort level in air conditioning system: Thermal comfort is the condition of mind that expresses satisfaction with the thermal environment and is assessed by subjective evaluation (ANSI/ASHRAE Standard 55).[1] Maintaining this standard of thermal comfort for occupants of buildings or other enclosures is one of the important goals of HVAC (heating, ventilation, and air conding) design engineers.
Thermal neutrality is maintained when the heat generated by human metabolism is allowed to dissipate, thus maintaining thermal equilibrium with the surroundings. The main factors that influence thermal comfort are those that determine heat gain and loss, namely metabolic rate, clothing insulation, air temperature, mean radiant temperature, air speed and relative humidity. Psychological parameters such as individual expectations also affect thermal comfort
UNIT VIII Load analysis
Do basic calculations of heating and cooling load requirements of a room: The first step toward helping you choose the right heating and air conditioning system for your home is to do a complete analysis of your present heating and air conditioning system and of your home to determine the right size equipment for your individual comfort needs.
According to the Department of Energy, a large percentage of people who replace their heating and air conditioning systems don’t take the time to get a proper system analysis and end up with the wrong size equipment. This results in higher utility bills, equipment that fails and needs to be replaced before its life expectancy is reached and a system that does not provide the comfort that you expected. UNIT XI Duct design and air distribution Apply scientific and engineering principles to analyze and design aspects of engineering systems that relate to refrigeration and air conditioning: Static pressure and velocity pressure increase anddecrease as the air proceeds through the ductwork,depending on the cross-sectional area of the flow, The total pressure of the airstream decreases as the air proceeds through the the ductwork due to the conversion of mechanical energy to heat caused by friction
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84 QUESTION BANK
Sub:- Refrigeration and Air-conditioning 1. Explain the working of Vapour compression refrigeration system with the help of a neat sketch. Mention the advantages of vapour compression refrigeration system over air refrigeration system. 2.An air refrigerator working on Bell coleman cycle takes in air at 1 barand at a temperature of 100 C. The air is compressed to 5 bar abs. The same is cooled to 250 C in the cooler before expanding in the expansion cylinder to cold chamber pressure of 1 bar. The compression and expansion laws followed are pv1.35 = C and pv1.3 = C respectively. Determine C.O.P of the plant and net refrigeration effect per kg of air. Take Cp = 1.009 kJ/kg K and R = 0.287 kJ/kg K for air. 3.State the principle of Steam jet refrigeration system. Explain the working of Steam jet refrigeration system 4.State main applications of Refrigeration. Explain Ice making plant with a suitable diagram.Briefly explain construction and working of Practical vapour absorption refrigeration system. Also mention the advantages of this system. 5.Mention the limitations of Simple vapour compression refrigeration cycle. Briefly explain the working of Two stage compression with water intercooler and liquid sub-cooler employed for vapour compression system. 6.Explain standard vapour compression refrigeration cycle with T-S and P-H diagram. What is the effect of sub-cooling on the performance of vapour compression refrigeration system? 7.A R-12 vapour compression system has saturated suction temperature of - 5°C and saturated discharge temperature of 40°C. The refrigerant vapour is dry-saturated at the suction of compressor and becomes superheated after compression. For one ton of refrigeration capacity, Calculate (i) Refrigerating effect (ii) mass flow rate (iii) Power and (iv) COP of the system. 8.Explain Boot-strap air refrigeration system with neat diagram. 9.Explain working of Li-Br vapour absorption refrigeration system with neat sketch. 10.Explain compound compression with flash chamber but without intercooler with system diagram and P-H diagram. 11.Explain multiple evaporator at different temperature with individual expansion valve with neat sketch and P-H diagram.
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12.A vapor compression machine is used to maintain a temperature of -230 C in refrigerated space. The ambient temperature is 370 C.The compressor takes in dry saturated vapor of F -12. Aminimum100 C temperature difference is required at the evaporator as well as condenser. There is no sub-cooling of liquid. If refrigerant flow is rate is 1kg/min find (i) Tonnage of refrigeration.(ii) Power requirement (iii)Ratio of COP of this cycle to COP of Carnot cycle. 13.Define refrigeration , State the Name of different types of system used for cooling of aircraft cabin, Also Explain with schematic diagram Bootstrap air Refrigeration system. 14.A Refrigerator working on Bell-Coleman cycle takes air into the compressor at 1 bar and – 50 C. It is compressed in compressor to a 5 bar and cooled to 250 C at the same pressure. It is further expanded in the expander to 1 bar and discharged to take cooling load. The isentropic efficiency of the compressor = 85% and the isentropic efficiency of the Expander = 90% find the following: (i) Refrigerating capacity of the system if air circulation is 40kg/min.(ii) KW capacity of motor required to run the compressor (iii) COP of the system.Take ᵞ =1.4 Cp =1kJ/kg Cv = 0.7 kJ/kg for air. 15.State the name of Different types evaporative devices used in refrigeration system Explain Automatic expansion valve. 16.Explain in brief Desirable Properties required for a good refrigerant. 17.A Two stage ammonia refrigeration system operates between overall pressure limits of 15 bar and 2 bar resply. The liquid is sub-cooled to 30oC. The temperature of desuperheated vapour leaving the water intercooler is also 30oC. The flash chamber separates the dry vapour at 5 bar pressure. The liquid refrigerant then expands to 2 bar,the evaporator pressure. The load on the evaporator is 50 kW. Calculate 1. Mass flow rate in different lines 2. Power required 3. COP. 18.A single compressor using R-12 as refrigerant has three evaporators of capacity 30TR,20TR and10TR.The temperature in the three evaporators is to be maintained at -10 oC , 5 oC and 10 oC respectively. The condenser pressure is 9.609 bar. The liquid refrigerant leaving the condenser is sub-cooled to 30oC. The vapour leaving the evaporators is dry and saturated. Assuming isentropic compression, calculate (a) the mass of refrigerant flowing through each evaporator; (b) the power required to drive the compressor; and (c) C.O.P. of the system. 19.What are desirable characteristics of ideal refrigerant? Explain how refrigerants are designated. 20.Draw neat and labeled sketches only of following: 1. Flooded evaporator 2. Dry expansion evaporator 3. Thermostatic expansion valve. 21.A two cylinder reciprocating compressor with 5% clearance is used in a refrigeration cycle to take load of 7.5 tons at 5oC refrigeration temperature and 40oC condensing temperature. The compression index is 1.35. The speed of piston is limited to 3m/s. take L/D =0.8 if refrigerant used is R-12 determine 1. Power conLaxmi Institute of Technology, Sarigam (Mechanical Department)
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sumption of compressor and COP of cycle 2. Volumetric efficiency of cycle 3. Bore , stroke and RPM of compressor. 22.How subcooling improves performance of vapour compression refrigeration cycle? 23.Explain multistage refrigeration system with intercooling between stages. 24.Write brief note on Hermetically sealed compressor. 25.Write brief note on natural refrigerants. 26. An air conditioned room that stands on a well ventilated basement measures 3 m wide, 3 m high and 6 m deep. One of the two 3 m walls faces west and contains a double glazed glass window of size 1.5 m by 1.5 m, mounted flush with the wall with no external shading. There are no heat gains through the walls other than the one facing west. Calculate the sensible, latent and total heat gains on the room, room sensible heat factor from the following information. What is the required cooling capacity? Inside conditions : 25oC dry bulb, 50 percent RH Outside conditions : 43oC dry bulb, 24oC wet bulb U-value for wall : 1.78 W/m2.K U-value for roof : 1.316 W/m2.K U-value for floor : 1.2 W/m2.K Effective Temp. Difference (ETD) for wall: 25oC Effective Temp. Difference (ETD) for roof: 30oC U-value for glass ; 3.12 W/m2.K Solar Heat Gain (SHG) of glass ; 300 W/m2 Internal Shading Coefficient (SC) of glass: 0.86 Occupancy : 4 (90 W sensible heat/person) (40 W latent heat/person) Lighting load : 33 W/m2 of floor area
Laxmi Institute of Technology, Sarigam (Mechanical Department)
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Enrollment No.________________Student sign:-_________ Gujarat Technological University
LAXMI INSTITUTE OF TECHNOLOGY, SARIGAM Academic year 2014-2015 Center Code: 086
Mid Semester Exam-I B. E. – IV(Sem – VIII)
Branch: Mechanical Engineering
Subject: Refrigration and air conditioning Date: 06/04/2015 Time: 9:00 am to 10:30 am
Subject Code:181901 Max. Marks: 30
Instructions: 1. Attempt all questions. 2. Make suitable assumptions wherever necessary. 3. Figures to the right indicate full marks. 4. Use Steam table OR Pschrometric chart table if require. Q.1
a) Define Refrigeration. State types of refrigeration systems. Explain BellColeman
[05]
air refrigeration cycle b) State the name of Different types evaporative devices used in refrigeration system [05] Explain Automatic expansion valve. Q.2
a) Define refrigeration , State the Name of different types of system used for cooling [05] of aircraft cabin, Also Explain with schematic diagram Bootstrap air Refrigeration system b) A dense air refrigeration machine operating on Bell-Coleman cycle works between [05] 3.4 bar and 17 bar. The temperature of air after the cooler is 15oC and after refrigeration is 6oC, for a refrigeration capacity of 6 tons calculate 1. Temperature after compression and expansion 2. Air circulation required in cycle per minute 3. Work of compression and expansion 4. Theoretical COP 5. Rate of water circulation required in the cooler in Kg/min if rate of temperature rise is limited to 30oC
Q.2
a) Explain with neat sketch working of Electrolux Refrigerator alsoexplain signifi- [05] cance of Hydrogen used in system. Laxmi Institute of Technology, Sarigam (Mechanical Department)
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b) A single compressor using R-12 as refrigerant has three evaporators of capacity 30TR,20TR and10TR.The temperature in the three evaporators is to be maintained at -10 oC ,5oC and 10oC respectively. The condenser pressure is 9.609 bar. The liquid refrigerant leaving the condenser is sub-cooled to 30oC. The vapour leaving the evaporators is dry and saturated. Assuming isentropic compression, calculate (a) the mass of refrigerant flowing through each evaporator; (b) the power required to drive [05] the compressor; and (c) C.O.P. of the system. From p-h chart: h3=230 KJ/Kg, h11= 348 KJ/Kg h8= 354 KJ/Kg h5= 356 KJ/Kg. Q.3
a) Draw neat and labeled sketches only of following:
[05]
1. Flooded evaporator 2. Dry expansion evaporator 3. Thermostatic expansion valve b) What are different methods used for design of the ducts and explain advantages of [05] each over other OR Q.3
a) Define following terms:
[05]
(i) Saturated air (ii) Specific humidity (iii) Relative humidity (iv) Absolute humidity (v) Dry bulb temperature (vi) Dew point temperature (vii) Wet bulb depression b) State important applications of refrigeration system. Explain construction and
[05]
working of an Ice plant.
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2161909
Production Technology
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SYLLABUS UNIT-I THEORY OF METAL CUTTING: Principles of metal machining, cutting tools and tool materials, tool signature, mechanics of chip removal, cutting forces and parameters effecting it, cutting fluids, tool wear, tool life, economics of machining. Multi point cutting tools, temperature measurement at tool-work interface and its Effects.
UNIT-II GEAR AND THREADS MANUFACTURING: Different types of Threads manufacturing methods, and tools involved, Different gear forming and generating methods with their special features, Gears finishing processes. .
UNIT-III JIGS & FIXTURES: Definition, its usefulness in mass production, design principles, locating systems and types of locators & clamps, jig bushes, design of jigs and fixtures for various machining operations.
UNIT-IV PRESSES AND PRESS WORK: Classification of presses, Classification of dies, cutting actions in dies, clearance, cutting forces, center of pressure design of press tools, methods of mounting of punches, scrap reduction, strip layout.
UNIT – V CONTROLS IN MACHINE TOOLS: Machine tool drives, Machine tool structures, Machine tool spindles, Special purpose machines, Capstan and turret lathes, single spindle and multi spindle automats, bar type and chucking type machines, Design of cam for single spindle automat Transfer Machines.
UNIT – VI NON-CONVENTIONAL MACHINING: EDM, IBM, ECM, ECG, CM, AJM, wire cut EDM, USM, LBM process principle, process parameters and their applications.
Laxmi Institute of Technology, Sarigam (Mechanical Department)
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LECTURE PLAN
Lect
Topics to be covered
2
Principles of metal machining. Cutting tools and tool materials.
3
Tool signature.
1.
5
Mechanics of chip removal. Cutting forces and parameters affecting it.
6
Cutting fluids.
7
Tool wear, tool life.
4
9
10
12 13
Date
Different types of Threads manufacturing methods.
Tools involved in thread manufacturing methods. Different gear forming methods.
16 17
Definition, its usefulness in mass produc-
15
Teaching Aids/ Books
1st UNIT TEST (25% of Syllabus)
Different gear generating methods. With their special features. Gears finishing processes.
14
Actual Date of Completion
Economics of machining. Multi point cutting tools. Temperature measurement at tool-work interface and its effects.
8
11
Planned Date
Signature of HoD &
Laxmi Institute of Technology, Sarigam (Mechanical Department)
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tion, 18
Design principles,
19
Locating systems
20
Types of locators
21
Types of clamps, jig bushes
22
Design of jigs
23
Design of fixtures
26
Various machining operations. Classification of presses, Classification of dies. Cutting actions in dies clearance.
27
Cutting forces,
24 25
Centre of pressure design of press tools Methods of mounting of punches. Methods of scrap reduction. Methods of strip layout.
28 29 30 31
32
33 34
35 36
2st UNIT TEST (75% of Syllabus)
Machine tool drives, Machine tool structures, Machine tool spindles, Special purpose machines. Capstan and turret lathes. Single spindle and multi spindle automats. Bar type and chucking type machines.
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37
38
39
40
41
42
43
44
45
Design of cam for single spindle automat Transfer Machines. EDM process principle, parameters and their applications. IBM process principle, parameters and their applications. ECM process principle, parameters and their applications. ECG process principle, parameters and their applications. CM process principle, parameters and their applications. AJM process principle, parameters and their applications. Wire cut EDM process principle, parameters and their applications. USM and LBM process principle, parameters and their applications. PUT 100% SYLLABUS
Lect. Topics to be Covered No.
References
UNIT I 1
Principles of metal machining.
2
Cutting tools and tool materials.
3
Tool signature.
4
Mechanics of chip removal.
5 6
Cutting forces and parameters affecting it. Cutting fluids.
7
Tool wear, tool life.
R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3
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8
Economics of machining.
9
Multi point cutting tools. Temperature measurement at tool-work interface and its effects.
10
R1,R2, R3 R1,R2, R3 R1,R2, R3
UNIT II 11 12 13 14 15 16
Different types of Threads manufacturing methods.
Tools involved in thread manufacturing methods. Different gear forming methods. Different gear generating methods. With their special features. Gears finishing processes.
R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3
UNIT III 17
Definition, its usefulness in mass production,
18
Design principles,
19
Locating systems
20 21
Types of locators Types of clamps, jig bushes Design of jigs
22
Design of fixtures
23
Various machining operations. UNIT-IV
24
Classification of presses, Classification of dies.
25
Cutting actions in dies clearance.
26
Cutting forces,
27 28 29 30
Centre of pressure design of press tools Methods of mounting of punches. Methods of scrap reduction. Methods of strip layout. UNIT – V
32
Machine tool drives, Machine tool structures,
33 34 35 36
Machine tool spindles, Special purpose machines. Capstan and turret lathes. Single spindle and multi spindle automats. Bar type and chucking type machines. Design of cam for single spindle automat Transfer Machines. UNIT – VI EDM process principle, parameters and their ap-
37 38
R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3
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39 40 41 42 43 44 45
plications. IBM process principle, parameters and their applications. ECM process principle, parameters and their applications. ECG process principle, parameters and their applications. CM process principle, parameters and their applications. AJM process principle, parameters and their applications. Wire cut EDM process principle, parameters and their applications. USM and LBM process principle, parameters and their applications.
R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3 R1,R2, R3
REFERENCES Sr. No.
TITLE
AUTHOR
PUBLISHER / EDITION
1
Production Technology
H.M.T.
2
Tool Design
Donaldson
Tata McGraw Hill Pub.
3
Production Technology
R. K. Jain
Khanna Pub
YEAR
HMT
PRACTICAL PLAN Subject Title : Production Technology
Session : Jan – May 2016
Subject Code: 2181903 Department : Mechanical Engineering
Semester : 8th Branch: Mechanical Engineering
Sr. List of Experiment No.
References
1
To study the different aspects of Single Point Cutting tool and Chip formation.
R1, R2, R3, R4
2 3
To measure the cutting forces for the given cutting conditions. To study the different variables influencing the tool wear and tool life.
R1, R2, R3, R4 R1, R2, R3, R4
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4
To study the temperature Measurement on chip tool interface.
5
Determination of chip-thickness ratio and shear plane angle during machining. To understand the effect of chosen parameters on the type of chip produced. To determine the Effect of Speed and Feed on the efficiency of Orthogonal Machining. To study different gear finishing processes. To study locating system and types of locators and clamps. To study machine tool drives and structures.
6 7 8 9 10
R1, R2, R3, R4 R1, R2, R3, R4 R1, R2, R3, R4 R1, R2, R3, R4 R1, R2, R3, R4 R1, R2, R3, R4 R1, R2, R3, R4
Abbreviations used in the reference column are explained at the end of the Lecture. Reference Book R1). Tool Design by Donaldson, Tata McGraw Hill Pub. R2). Metal cutting Principles by Trent McGraw Hill Pub. R3). Workshop Technology Vol.II by Raghuvanshi , Dhanpat rai Pub. R4). Production Technology by R.K.Jain, Khanna Pub.
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UNIT WISE (BLOW: UP) UNIT I THEORY OF METAL CUTTING THE MECHANICS OF CHIP FORMATION: A typical metal cutting process can be schematically represented as shown in Fig. wedge-shaped tool is made to move relative to the work piece. As the tool makes contact with the meta1, it exerts a pressure on it resulting in the compression of the metal near the tool tip. This induces shear-type deformation within the metal and it starts moving upward along the top face of tool. As the tool advances, the material ahead of it is sheared continuously along a plane called Shear plane”.
This shear plane is actually a narrow zone (of the order of about 0.025 mm) and extends from the cutting edge of the tool to the surface of the work piece. The cutting edge of the tool is formed by two intersecting surfaces. Tool Designation:
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The tool designation or tool signature, under ASA system is given in the order given below Back rake, Side rake, End relief, Side relief, End cutting edge angle, Side cutting edge angle, and nose radius that is, If tool designation is: αb- αs - θe – Ce – Cs - R 1) Orthogonal Rake System (ORS) In this system the planes for designating tools are the plane containing the principal or side cutting edge and the plane normal to it. METHOD OF MACHINING:
(i)
Orthogonal metal cutting-Two dimensional cutting
(ii)
Oblique metal cutting-Three dimensional cutting
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UNIT II GEAR AND THREADS MANUFACTURING GRINDING PROCESS:
Selecting which of the following grinding operations to be used is determined by the size, shape, features and the desired production rate.
Surface grinding
Surface grinding uses a rotating abrasive wheel to remove material, creating a flat surface. The tolerances that are normally achieved with grinding are ± 2 × 10−4 inches for a grinding a flat material and ± 3 × 10−4 inches for a parallel surface (in metric units: 5 μm for flat material and 8 μm for parallel surface).
The surface grinder is composed of an abrasive wheel, a workholding device known as a chuck, either electromagnetic or vacuum, and a reciprocating table.
Typical workpiece materials include cast iron and steel. These two materials do not tend to clog the grinding wheel while being processed. Other materials are aluminum, stainless steel, brass and some plastics.
Cylindrical grinding
Cylindrical grinding (also called center-type grinding) is used to grind the cylindrical surfaces and shoulders of the workpiece. The workpiece is mounted on centers and rotated by a devise known as a drive dog or center driver. The abrasive wheel and the workpiece are rotated by separate motors and at different speeds. The table can be adjusted to produce tapers. The wheel head can be swiveled.
Creep-feed grinding (CFG) was invented in Germany in the late 1950s by Edmund and Gerhard Lang. Unlike normal grinding, which is used primarily to finish surfaces, CFG is used for high rates of material removal, competing with Laxmi Institute of Technology, Sarigam (Mechanical Department)
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milling and turning as a manufacturing process choice. Depths of cut of up to 6 mm (0.25 inches) are used along with low workpiece speed. Surfaces with a softer-grade resin bond are used to keep workpiece temperature low and an improved surface finish up to 1.6 micrometres Rmax.
High-efficiency deep grinding (HEDG) uses plated superabrasive wheels, which never need dressing and last longer than other wheels. This reduces capital equipment investment costs. HEDG can be used on long part lengths, and removes material at a rate of 1 in3 in 83 sec. It requires high spindle power and high spindle speeds.
Peel grinding, patented under the name of Quickpoint in 1985 by Erwin Junker Maschinenfabrik, GmbH in Nordrach, Germany, uses a tool with a with superabrasive nose and can machine cylindrical parts.
VIPER (Very Impressive Performance Extreme Removal), 1999, is a process patented by Rolls-Royce and is used in aerospace manufacturing to produce turbine blades. It uses a continuously dressed aluminum oxide grinding wheel running at high speed. CNC-controlled nozzles apply refrigerated grinding fluid during the cut. VIPER is performed on equipment similar to a CNC machining center, and uses special wheels.
Ultra-high speed grinding (UHSG) can run at speeds higher than 40,000 fpm (200 m/s), taking 41 sec to remove 1 in.of material, but is still in the R&D stage. It also requires high spindle power and high spindle speeds.
UNIT III JIGS & FIXTURES LOCATING GUIDELINES
No single form of location or type of locator will work for every work holder. To properly perform the necessary location, each locator must be carefully planned into the design. The following are a few guidelines to observe in choosing and applying locators. Positioning Locators The primary function of any locator is to reference the work piece and to ensure repeatability. Unless the locators are properly positioned, however, these functions cannot be accomplished. When positioning locators, both relative to the work holder and to the workpiece, there are a few basic points to keep in mind. Whenever practical, position the locators so they contact the workpiece on a machined surface. The machined surface not only provides repeatability but usually offers a more-stable form of location. The work piece itself determines the areas of the machined surface used for location. In some instances, the entire surface may be machined. In others, especially with castings, only selected areas are machined. Laxmi Institute of Technology, Sarigam (Mechanical Department)
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The best machined surfaces to use for location, when available, are machined holes. As previously noted, machined holes offer the most-complete location with a minimal number of locators. The next configuration that affords adequate repeatability is two machined surfaces forming a right angle. These characteristics are well suited for the six-point locational method. Regardless of the type or condition of the surfaces used for location, however, the primary requirement in the selection of a locating surface is repeatability. To ensure repeatability, the next consideration in the positioning of locators is the spacing of the locators themselves. As a rule, space locators as far apart as practical. This is illustrated in Figure 9-12. Both workpieces shown here are located with the six-point locating method. The only difference lies in the spacing of the locators. In the part shown at (b), both locators on the back side are positioned close to each other. In the part at (a), these same locators are spaced further apart. The part at (a) is properly located; the part at (b) is not. Spacing the locators as far apart as practical compensates for irregularities in either the locators or the workpiece. Its also affords maximum stability.
Figure 9-12. Locators should be spaced as far apart as practical to compensate for slight irregularities and for maximum stability. The examples in Figure 9-13 show conditions that may occur when locators are placed too close together if the center positions of the locators are misaligned by .001". With the spacing shown at (a), this condition has little effect on the location. But if the locating and spacing were changed to that shown at (b), the .001" difference would have a substantial effect. Another problem with locators placed too close together is shown at (c). Here, because the locators are too closely spaced, the part can wobble about the locators in the workholder.
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Figure 9-13. Positioning locators too close together will affect the locational accuracy. Controlling Chips The final consideration in the placement of locators involves the problem of chip control. Chips are an inevitable part of any machining operation and must be controlled so they do not interfere with locating the workpiece in the workholder. Several methods help minimize the chip problem. First, position the locators away from areas with a high concentration of chips. If this is not practical, then relieve the locators to reduce the effect of chips on the location. In either case, to minimize the negative effects of chips, use locators that are easy to clean, self-cleaning, or protected from the chips. Figure 3-14 shows several ways that locators can be relieved to reduce chip problems.
Figure 9-14. Locators should be relieved to reduce locational problems caused by chips. Coolant build-up can also cause problems. Solve this problem by drilling holes, or milling slots, in areas of the workholder where the coolant is most likely to build up. With some workholders, coolant-drain areas can also act as a removal point for accumulated chips. Laxmi Institute of Technology, Sarigam (Mechanical Department)
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When designing a workholder, always try to minimize the chip problem by removing areas of the tool where chips can build up. Omit areas such as inside corners, unrelieved pins, or similar features from the design. Chip control must be addressed in the design of any jig or fixture. CLAMPING GUIDELINES Locating the workpiece is the first basic function of a jig or fixture. Once located, the workpiece must also be held to prevent movement during the operational cycle. The process of holding the position of the workpiece in the jig or fixture is called clamping. The primary devices used for holding a workpiece are clamps. To perform properly, both the clamping devices and their location on the workholder must be carefully selected. Factors in Selecting Clamps Clamps serve two primary functions. First, they must hold the workpiece against its locators. Second, the clamps must prevent movement of the workpiece. The locators, not the clamps, should resist the primary cutting forces generated by the operation. Holding the Workpiece Against Locators. Clamps are not intended to resist the primary cutting forces. The only purpose of clamps is to maintain the position of the workpiece against the locators and resist the secondary cutting forces. The secondary cutting forces are those generated as the cutter leaves the workpiece. In drilling, for example, the primary cutting forces are usually directed down and radially about the axis of the drill. The secondary forces are the forces that tend to lift the part as the drill breaks through the opposite side of the part. So, the clamps selected for an application need only be strong enough to hold the workpiece against the locators and resist the secondary cutting forces. The relationship between the locators and clamps can be illustrated with a milling-machine vise. In Figure 9-22, the vise contains both locating and clamping elements. The solid jaw and vise body are the locators. The movable jaw is the clamp. The vise is normally positioned so that the locators resist the cutting forces. Directing the cutting forces into the solid jaw and vise body ensures the accuracy of the machining operation and prevents workpiece movement. In all workholders, it is important to direct the cutting forces into the locators. The movable vise jaw, like other clamps, simply holds the position of the workpiece against the locators.
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Figure 9-22. A vise contains both locating and clamping elements. Holding Securely Under Vibration, Loading, and Stress. The next factors in selecting a clamp are the vibration and stress expected in the operation. Cam clamps, for example, although good for some operations, are not the best choice when excessive vibration can loosen them. It is also a good idea to add a safety margin to the estimated forces acting on a clamp. Preventing Damage to the Workpiece. The clamp chosen must also be one that does not damage the workpiece. Damage occurs in many ways. The main concerns are part distortion and marring. Too much clamping force can warp or bend the workpiece. Surface damage is often caused by clamps with hardened or non-rotating contact surfaces. Use clamps with rotating contact pads or with softer contact material to reduce this problem. The best clamp for an application is one that can adequately hold the workpiece without surface damage. Improving Load/Unload Speed. The speed of the clamps is also important to the workholder's efficiency. A clamp with a slow clamping action, such as a screw clamp, sometimes eliminates any profit potential of the workholder. The speed of clamping and unclamping is usually the most-important factor in keeping loading/unloading time to a minimum. Positioning the Clamps The position of clamps on the workholder is just as important to the overall operation of the tool as the position of the locators. The selected clamps must hold the part against the locators without deforming the workpiece. Once again, since the purpose of locators is to resist all primary cutting forces generated in the operation, the clamps need only be large enough to hold the workpiece against the locators and to resist any secondary forces generated in the operation. To meet both these conditions, position the clamps at the most-rigid Laxmi Institute of Technology, Sarigam (Mechanical Department)
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points of the workpiece. With most workholders, this means positioning the clamps directly over the supporting elements in the baseplate of the workholder, Figure-9-23a. In some cases the workpiece must be clamped against horizontal locators rather than the supports, Figure 3-23b. In either case, the clamping force must be absorbed by the locating elements.
Figure 9-23. Clamps should always be positioned so the clamping force is directed into the supports or locators. For workholders with two supports under the clamping area of the workpiece, two clamps should be used — one over each support, Figure 3-24a. Placing only one clamp between the supports can easily bend or distort the workpiece during the clamping operation. When the workpiece has flanges or other extensions used for clamping, an auxiliary support should be positioned under the extended area before a clamp is applied, Figure 3-24b.
Figure 9-24. The number and position of clamps is determined by the workpiece and its supports. Another consideration in positioning clamps is the operation of the machine tool throughout the machining cycle. The clamps must be positioned so they do not interfere with the operation of the machine tool, during either the cutting or return cycle. Such positioning is especially critical with numerically controlled Laxmi Institute of Technology, Sarigam (Mechanical Department)
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machines. In addition to the cutters, check interference between the clamps and other machine elements, such as arbors, chucks, quills, lathe carriages, and columns. When fixturing an automated machine, check the complete tool path before using the workholder. Check both the machining cycle and return cycle of the machine for interference between the cutters and the clamps. Occasionally programmers forget to consider the tool path on the return cycle. One way to reduce the chance of a collision and eliminate the need to program the return path is simply to raise the cutter above the highest area of the workpiece or workholder at the end of the machining cycle before returning to the home position. Most clamps are positioned on or near the top surface of the workpiece. The overall height of the clamp, with respect to the workpiece, must be kept to a minimum. This can be done with gooseneck-type clamps, Figure 3-25. As shown, the gooseneck clamp has a lower profile and should be used where reduced clamp height is needed.
Figure 9-25. Using gooseneck clamps is one way to reduce the height of the clamps. The size of the clamp-contact area is another factor in positioning a clamp. To reduce interference between the clamp and the cutter, keep the contact area as small as safely possible. A small clamping area reduces the chance for interference and also increases the clamping pressure on the workpiece. The overall size of the clamp is another factor to keep in mind. The clamp must be large enough to properly and safely hold the workpiece, but small enough to stay out of the way.
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UNIT-IV PRESSES AND PRESS WORK Metal forming is one of the manufacturing processes which are almost chip less. These operations are mainly carried out by the help of presses and press tools. These operations include deformation of metal work pieces to the desired size and size by applying pressure or force. Presses and press tools facilitate mass production work. These are considered fastest and most efficient way to form a sheet metal into finished products. Objectives After studying this unit, you should be able to understand Introduction of press tool, Major components of press working system, Different criteria of classification of presses, Different types of presses, Description of important parts of a press, Specifications of a press, other press working tools, like punch and die, Components of press working system, Different types of die sets, and Design considerations for die set design. PRESS A press is a sheet metal working tool with a stationary bed and a powered ram can be driven towards the bed or away from the bed to apply force or required pressure for various metal forming operations. A line diagram of a typical pres is explained in the Figure 2.1 hydraulic system. The relative positions of bed and ram in the press are decided by the structure of its frame. The punch is generally gripped into the punch holder and punch holder is attached to ram. A blaster steel plate is attached to the bed of the press and die is mounted on the blaster steel plate.
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Figure 3.1: Line Diagram of a Typical Press Presses are available in a variety of capacities, power systems and frame type. Meaning of capacity of press is its capability to apply the required force to complete the operation. Power and Drive System Power systems on presses are either hydraulic presses use a large piston and cylinder to drive the ram. This system is capable to provide longer ram strokes than mechanical dries. It gives a consistent applied load. Its working is comparatively slower. These presses can be single action or double action or so on. Number of actions depends on the number of slides operating independently. Mechanical presses are used several types of drive mechanisms. These drives includes eccentric, crankshaft, knuckle joint, etc. These drives are used to convert rotational motion given by a motor into linear motion of the ram. A fly wheel is generally used as reservoir of energy for forging operations. These presses are recommended for blanking and punching operations as the involved drives are capable to achieve very high forces at the end of their strokes. Press working is used in large number of industries like automobile industry, aircraft industry, telecommunication electrical appliance, utensils making industry are major examples. TYPES OF PRESSES There are different criteria of classification of presses into different categories. These criteria, related classifications and their descriptions are discussed below. According to the Power Source These power sources are categorized as: Manually Operated or Power Driven These presses are used to process thin sheet metal working operations where less pressure or force is required. These are operated by manual power. Most of manually operated presses are hand press, ball press or fly press. Power Presses Power presses are normally driven by mechanical mechanism or hydraulic system. Power source of these presses may be electric motor or engine. According to the Type and Design of Frame Laxmi Institute of Technology, Sarigam (Mechanical Department)
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The type and design of frame depending on the design of frame these are classified as inclinable, straight side, adjustable bed, gap frame, horning and open end. 35 Press and Press Tools Inclinable Frame Press Its frame is called inclinable due to its capability to tilt back upto some angle. It can be locked into nay of its inclined position as shown in Figure 3.2. Its back is open to exit the scrap so it is also called open back inclinable press.
Figure 3.2 : Inclinable Frame Press Gap Frame Press These presses have larger frame openings, that means a wide gap between its base and ram to accommodate larger workpieces. It also has longer beds, as shown in Figure 3.3.
Figure 3.3: Line Diagram of a Gap Frame Press Straight Side Press These presses have straight side type frame which is preferred for presses having larger bed area and high tonnage. This offers greater rigidity and capable of longer strokes. The frame consists of vertical and straight sides so it is called straight side press. Adjustable Bed Type Press It is also called column and knee type press because it has a knee type bed supported on its column shaped frame. Its bed (knee) can be adjusted at any desirable height by Laxmi Institute of Technology, Sarigam (Mechanical Department)
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moving it vertically up or down with the help of power screws. In this structure there is slight lack of rigidity as compared to other structures. It is shown in Figure 3.4.
Figure 3.4 : Adjustable Bed Type Press 36 Manufacturing Processes-III Open End Press It has a solid type of vertical frame with all sides open. Driving mechanism is housed at the back and ram controlling mechanism at the front. It is easily to accommodate workpiece and dies in this type of structure. It is identified as light duty machine. Horning Press It consists of a vertical frame, top of which over hangs towards the front. The overhanging portion serves for housing for driving mechanism and ram control. The frame consists of a front face as a work table called horn. According to the Position of Frame Presses can also be categorized by the position of frame as described below. Inclinable Frame Vertical Frame Vertical frame type of press is already been discussed, it cannot be adjusted like inclinable frame. Gap, adjustable bed, straight side, open end and honing presses are the example of vertical frames. Horizontal Frame It has a fixed frame in horizontal position. It provides the facility of auto ejection of produced part and scrap due to gravity. Inclined Frame Like inclinable frame, inclined frame press has an inclined frame but fixed, it cannot be adjusted to any other angle. According to the Actions According to the number of actions it can be categorized as single action, double action or triple action press. Here number of actions is same as the number of rams on the press. According to Mechanism Used to Transmit Power to Ram Crank Press It consists of crankshaft driven by a flywheel, rotary motion of the crankshaft is converted into reciprocating motion with the help of a connecting rod connected to ram. Cam Driven Press Laxmi Institute of Technology, Sarigam (Mechanical Department)
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In this press, a cam is used to press the ram down words and suitably located springs restore the original position of ram when pressure applied is removed. This mechanism has a limitation of size of the press. Eccentric Press In this press, the driving shaft carries an eccentric integral with it. One end of the connecting rod carried an attachment of revolving eccentric and its other end is connected to ram. As the eccentric shaft revolves, the offset between the eccentric centre and the centre of rotation of the shaft provides the required movement. Knuckle Press This press is driven with the help of knuckle joint mechanism. The main advantage of this press is partial back thrust is transferred to crankshaft, its major portion is transferred to back crown which is capable to hear. This 37 Press and Press Tools enables the application of this press for heavier jobs with high intensity of blows. These presses are recommended for coining, squeezing, extruding and embossing. They have a limitation of shorter stroke lengths. Toggle Press These presses work on toggle mechanism and used for double and triple action presses for driving the outer rams. However, crankshaft drive is used for the inner ram. These are used for large draw dies, in which this mechanism actuates the blank holder whereas the punch is operated by the crank driven inner ram. Screw Press This is known as power screw or percussion press. There is a vertical are like frame, its job forms a nut. There is a flywheel at the top of and engages the ram at its bottom. The flywheel is driven by a friction disc and the rotating screw lowers and raises the ram. The flywheel is accelerated by friction drive. Its total energy is expanded in striking the work, bringing it to a halt. The intensity of blow can be regulated by adjusting the height of the die. Higher the position of the die, lesser the speed of the flywheel and hence lower the intensity of blow. These presses have a limitation that the ram movement is slow so these are recommended for sheet metal work only. Hydraulic Press These presses have a piller type construction or carry the hydraulic cylinder at the top of the crown. These presses provide longer stroke than mechanical presses with adjustable intensity of blow. Their stroke length can also be adjusted with full tonnage. These are recommended for deep drawing, extruding and plastic moulding. Rack and Pinion Press Rack and pinion driven presses are called rack and pinion presses meant for long strokes. Major advantage is faster operation of this press due to involvement of quick return motion. There are some limitations of this press. Load bearing capability of rack and pinion mechanism is very low so these are light duty machines. Ram movement is slightly slower. These presses have very limited use now-a-days. According to Number of Drive Gears Number of drive gears means number of gears attached at the ends of crankshaft, used to drive it. Smaller presses have single drive and larger presses may be double drive crankshafts. Very large presses with longer beds, carry long crankshafts. They have risk of twisting. These crankshafts are provided with one driving gear at each ends, these presses are named as twine drive presses. If a press carries two crankshafts each having a twin drive, such presses are called quadruple drive presses. Laxmi Institute of Technology, Sarigam (Mechanical Department)
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According to Number of Crankshaft in a Press According to the number of crankshafts used in a press, these are directly classified as single crank (having one crankshaft) double crank (having two crankshafts).
UNIT – V CONTROLS IN MACHINE TOOLS A general purpose machine tool is basically comprised of power drive and kinematic system for the essential formative and auxiliary tool – work motions and a rigid body or structure to accommodate all of the above. But several additional elements or devices called accessories are also essentially required for that machines’ general functioning, mainly for properly holding and supporting the workpiece and the cutting tool depending upon the type and size of the tool – work and the machining requirements. These accessories generally include for instance, in case of; •Centre lathes: chucks, collets, face plate, steady and follower rests, centres, tool holders etc. •Drilling machines: vices, clamps, drill chuck and sockets etc. •Shaping and planning machines: vices, clamps, tool holders etc. •Milling machines: vices, clamps, parallel blocks, collets, job – support like tailstock etc. Such accessories, inevitable for general functioning of the machine tools, are usually enlisted in the supply list and covered within the to tal price of the machine tools. Occasionally, some accessories are ordered separately as and when required. ATTACHMENTS Each general purpose conventional machine tool is designed and used for a set of specific machining work on jobs of limited range of shape and size. But often some unusual work also need to be done in a specific machine tools, e.g. milling in a lathe, tapping in a drilling machine, gear teeth cutting in shaping machine and soon. Under such conditions, some special devices or systems are additionally used being mounted in the ordinary machine tools. Such additional special devices, which augment the processing capability of any ordinary machine tool, are known as Attachments, Unlike accessories, Attachments are not that inevitable and procured separately as and when required and obviously on extra payment. Some attachments being used in the general purpose conventional machine tools are : • In centre lathes: Ο Taper turning attachment ο Copy turning attachments ο Milling and cylindrical ο grinding attachments ο Spherical turning attachments ο Relieving attachment • In drilling machines: Ο Tapping attachment • In shaping machines: Ο Double cut tool head ο Thread rolling attachment Laxmi Institute of Technology, Sarigam (Mechanical Department)
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ο Matter son’s attachment (gear teeth cutting) • In planning machines: Ο Contour forming attachment ο Helical grooving attachment ο Oil grooving attachments ο Milling and grinding attachments • In milling machines: Ο universal milling attachment ο indexing / dividing head ο rotary table ο slotting attachment Conditions and Places Suitable For Application of Attachments in Machine Tools. With the rapid and vast advancement of science and technology, the manufacturing systems including machine tools are becoming more and more versatile and productive on one hand for large lot or mass production and also having flexible automation and high precision on the other hand required for production of more critical components in pieces or small batches. With the increase of versatility and precision (e.g., CNC machines) and the advent of dedicated high productive special purpose machines, the need of use of special attachments is gradually decreasing rapidly. However, some attachments are occasionally still being used on no automatic general purpose machine tools in some small and medium scale machining industries; •when and where machining facilities are very limited •when production requirement is very small, may be few pieces •product changes frequently as per job order •repair work under maintenance, especially when spare parts are not available •when CNC machine tools and even reasonable number of Conventional machine tools cannot be afforded. Therefore, use of aforesaid attachments is restricted to manufacture of unusual jobs in small quantities under limited facilities and at low cost. Working Principles And Application Of Various Attachments In Different Machine Tools. (a) Attachments used in centre lathes •Taper turning attachment Taper cylindrical surface, which is a very common feature of several engineering components, is generally produced in lathes in a number of methods, depending upon length and angle of the tapered position of the job, such as offsetting tailstock, swiveling the compound slide using form tool and Combined feed motions. But jobs with wide ranges of length and angle of taper, are easily machined by using a simple attachment, called taper turning attachment. Fig. 4.6.1 schematically shows a taper turning attachment where the cross slide is delinked from the saddle and is moved crosswise by the guide block which moves along the guide bar preset at the desired taper angle. Thus, the cutting tool, which is fitted on the cross slide through the tool post and the compound slide, also moves along with the guide black in the Same direction resulting the desired taper turning. • Copy turning attachment There are two common types of copy turning; Ο mechanical type Ο hydraulic type Laxmi Institute of Technology, Sarigam (Mechanical Department)
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Ο Mechanical copying A simple mechanical type copy turning attachment has been schematically shown in Fig. 4.6.2. The entire attachment is mounted on the saddle after removing the cross slide from that. The template replicating the job-profile desired is clamped at a suitable position on the bed. The stylus is fitted in the spring loaded tool slide and while travelling longitudinally along with saddle moves in transverse direction according to the template profile enabling the cutting tool produce the same profile on the job as indicated in the Fig. 4.6.2
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Ο Hydraulic copying attachment- the mounting and working principle of hydraulic copying attachment for profile turning in centre lathe are schematically shown in Fig. 4.6.3. Here also, the stylus moves along the template profile to replicate it on the job. In mechanical system (Fig. 4.6.2) the heavy cutting force is transmitted at the tip of the stylus, which causes vibration, large friction and faster wear and tear. Such problems are almost absent in hydraulic copying, where the stylus works simply as a valve – spool against a light spring and is not affected by the cutting force. Hydraulic copying attachment is costlier than the mechanical type but works much smoothly and accurately. The cutting tool is rigidly fixed on the cross slide which also acts as a valve – cum – cylinder as shown. So long the stylus remains on a straightedge parallel to the lathe bed, the cylinder does not move transversely and the tool causes straight turning. As soon as the stylus starts moving along a slope or profile, i.e., in cross feed direction the ports open and the cylinder starts moving accordingly against the piston fixed on the saddle. Again the movement of the cylinder i.e., the slide holding the tool, by same amount travelled by the stylus, and closes the ports. Repeating of such quick incremental movements of the tool, Δx and Δy result in the profile with little surface roughness.
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• Milling attachment This is a milling head, comprising a motor, a small gear box and a spindle to hold the milling cutter, mounted on the saddle after removing the cross slide etc. as shown in Fig. 4.6.4. Milling attachments are generally used for making flat surfaces, straight and helical grooves, splines, long and deep screw threads, worms etc. in centre lathes by using suitable milling cutters.
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• Grinding attachment Grinding attachment is very similar to milling attachment. But in the former, there is no gear box and the spindle speed is much higher as needed for grinding operation. Such attachments are employed for external and internal cylindrical grinding, finishing grooves, splines etc. and also for finish grinding of screw threads in centre lathe. But unlike dedicated machines, attachments cannot provide high accuracy and finish. •Spherical turning attachments these simple attachments are used in centre lathes for machining spherical; both convex and concave surfaces and similar surfaces. Fig. 4.6.5 schematically visualizes the usual setting and working principle of such attachments. In Fig. 4.6.5 (b), the distance Rican be set according to the radius of curvature desired. In the type shown in Fig. 4.6.5 (a) the desired path of the tool tip is controlled by the profile of the template which is pre-made as per the radius of curvature required. The saddle is disconnected from the feed rod and the lead screw. So when the cross slide is moved manually in transverse direction, the tool moves axially freely being guided by the template only.
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•Relieving attachment The teeth of form relieved milling cutters like gear milling cutters, taps, hobs etc. are provided with flank having Archimedean spiral curvature. Machining and grinding of such curved flanks of the teeth need relieving motion to the tool (or wheel) as indicated in Fig. 4.6.6 (a). The attachment schematically shown in Fig. 4.6.6 (b) is comprised of a spring loaded bracket which holds the cutting tool and is radially reciprocated on the saddle by a plate cam driven by the feed rod as indicated.
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UNIT – VI NON-CONVENTIONAL MACHINING As we are in the era of fastest growing technological development and advancement in manufacturing technology we need quick and better results. Non conventional machining processes enable us to get consistency and accuracy in our desired manufacturing techniques. In the field of engineering, development of such techniques has lead to revolution in the field of manufacturing. Tasks which are assumed to be impossible in past can be done within fraction of seconds. Machining of many metals which needed too much time and used to be too laborious are now simplified and easied. NON-TRADITIONAL MACHINING However development of newer methods has always been the Endeavour of engineering personnel and scientists. The main ideas behind such endeavors have generally been the economic considerations, replacements of existing manufacturing methods by more efficient and quicker ones, achievement of higher accuracies and quality of surface finish, adaptability of cheaper materials in place of costlier ones and developing methods of machining such materials which cannot be easily machined through the conventional methods etc. Of all this reasons, the last one has contributed considerably to the post-war developments in machining methods, particularly because of the use of a large number of ‘hard to machine’ materials in the modern industry. A few of such materials are tungsten, hardened and stainless steel, inconel, uranium, beryllium and some high strength steel alloys. The increasing utility of such materials in Laxmi Institute of Technology, Sarigam (Mechanical Department)
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the modern industry has forced research engineers to develop newer machining methods, so as to have full advantage of these costly materials. The use of such costly and hard-to-machine material is quite common in aircraft industry, research equipment, nuclear plants, missile technology, sophisticated equipments, manufacturing industries etc. To meet the needs of such industries, whereas on one hand newer materials have been developed at the same time a number of newer machining methods have been evolved for achining of these materials. These machining methods are known as Unconventional or N on-traditional Machining Methods.
ABRASIVE JET MACHINING (AJM) In Abrasive Jet Machining (AJM), abrasive particles are made to impinge on the work material at a high velocity. The high velocity abrasive particles remove the material by micro-cutting action as well as brittle fracture of the work material. In AJM, generally, the abrasive particles of around 50 μm grit size would impinge on the work material at velocity of 200 m/s from a nozzle of I.D. of 0.5 mm with a standoff distance of around 2 mm. The kinetic energy of the abrasive particles would be sufficient to provide material removal due to brittle fracture of the work piece or even micro cutting by the abrasives.
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Water jet cutting can reduce the costs and speed up the processes by eliminating or reducing expensive secondary machining process. Since no heat is applied on the materials, cut edges are clean with minimal burr. Problems such as cracked edge defects, crystalisation, hardening, reduced wealdability and machinability are reduced in this process. Water jet technology uses the principle of pressurizing water to extremely high pressures, and allowing the water to escape through a very small opening called “orifice” or “jewel”. Water jet cutting uses the beam of water exiting the orifice to cut soft materials. This method is not suitable for cutting hard materials. The inlet water is typically pressurized between 1300 –4000 bars. This high pressure 0.18 to 0.4 mm in diameter.
USM is mechanical material removal process or an abrasive process used to erode holes or cavities on hard or brittle work piece by using shaped tools, high frequency mechanical motion and an abrasive slurry. USM offers a solution to the expanding need for machining brittle materials such as single crystals, glasses and polycrystalline ceramics, and increasing complex operations to provide intricate shapes and work piece profiles. It is therefore used extensively in machining hard and brittle materials Laxmi Institute of Technology, Sarigam (Mechanical Department)
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that are difficult to machine by traditional manufacturing processes. The hard particles in slurry are accelerated toward the surface of the work piece by a tool oscillating at a frequency up to 100 KHz - through repeated abrasions, the tool machines a cavity of a cross section identical to its own.
Figure 10: Schematic of ultrasonic machine tool USM is primarily targeted for the machining of hard and brittle materials (dielectric or conductive) such as boron carbide, ceramics, titanium carbides, rubies, quartz etc. USM is a versatile machining process as far as properties of materials are concerned. This process is able to effectively machine all materials whether they are electrically conductive or insulator. For an effective cutting operation, the following parameters need to be carefully considered:• The machining tool must be selected to be highly wear resistant, such as high-carbon steels. • The abrasives (25-60 μm in dia.) in the (water-based, up to 40% solid volume) slurry Includes: Boron carbide, silicon carbide and aluminum oxide. Electrical Discharge Machining (EDM) Electrical discharge machining (EDM) is one of the most widely used nontraditional machining processes. The main attraction of EDM over traditional machining processes such as metal cutting using different tools and grinding is that this technique utilises thermoelectric process to erode undesired materials from the work piece by a series of discrete electrical sparks between the work piece and the electrode.
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A picture of EDM machine in operation The traditional machining processes rely on harder tool or abrasive material to remove the softer material whereas non-traditional machining processes such as EDM uses electrical spark or thermal energy to erode unwanted material in order to create desired shape. So, the hardness of the material is no longer a dominating factor for EDM process. A schematic of an EDM process is shown in Figure 2, where the tool and the work piece are immersed in a dielectric fluid. EDM removes material by discharging an electrical current, normally stored in a capacitor bank, across a small gap between the tool (cathode) and the work piece (anode) typically in order. Electrochemical machining (ECM) is a metal-removal process based on the principle of reverse electroplating. In this process, particles travel from the anodic material (work piece) toward the cathodic material (machining tool). A current of electrolyte fluid carries away the depleted material before it has a chance to reach the machining tool. The cavity produced is the female mating image of the tool shape.
Similar to EDM, the work piece hardness is not a factor, making ECM suitable for machining difficult-to –machine materials. Difficult shapes can be made by this process on materials regardless of their hardness. A schematic representation of ECM process is shown in Figure. The ECM tool is positioned very close to the work piece and a low voltage, high amperage DC current is passed between the work piece and electrode. Some of the shapes made by ECM process. Laser-beam machining is a thermal material-removal process that utilizes a highenergy, coherent light beam to melt and vaporize particles on the surface of metallic and non-metallic workpieces. Lasers can be used to cut, drill, weld and mark. LBM is particularly suitable for making accurately placed holes. A schematic of laser beam machining is shown in Figure 12. Different types of lasers are available for manufacturing operations which are as follows:
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• CO2 (pulsed or continuous wave): It is a gas laser that emits light in the infrared region. It can provide up to 25 kW in continuous-wave mode. • Nd:YAG: Neodymium-doped Yttrium-Aluminum-Garnet (Y3Al5O12) laser is a solid- state laser which can deliver light through a fibre-optic cable. It can provide up to 50 kW power in pulsed mode and 1 kW in continuous-wave mode. EBM the gun is operated in pulse mode. This is achieved by appropriately biasing the biased grid located just after the cathode. Switching pulses are given to the bias grid so as to achieve pulse duration of as low as 50 μs to as long as15 ms. Beam current is directly related to the umber of electrons emitted by the cathode or available in the beam. Beam current once again can be as low as 200 μ amp to 1 amp. Increasing the beam current directly increases the energy per pulse. Similarly increase in pulse duration also enhances energy per pulse. High-energy pulses (in excess of 100 J/pulse) can machine larger holes on thicker plates.
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The energy density and power density is governed by energy per pulse duration and spot size. Spot size, on the other hand is controlled by the degree of focusing achieved by the electromagnetic lenses. A higher energy density, i.e., for a lower spot size, the material removal would be faster though the size of the hole would be smaller. The plane of focusing would be on the surface of the work piece or just below the surface of the work piece.
ASSIGNMENT TOPICS
Sr. No.
TOPIC
1
THEORY OF METAL CUTTING
2
GEAR AND THREADS MANUFACTURING
3
JIGS & FIXTURES
4
PRESSES AND PRESS WORK
5
1. CONTROLS IN MACHINE TOOLS
6
2. NON-CONVENTIONAL MACHINING
SR Chapter - 1 THEORY OF METAL CUTTING NO 1 The following equation for tool life has been obtained for H. S. S. tool. VT 0.13 f 0.6 d 0.3 = C A 60 minute tool life was obtained while cutting at V = 40 m/min, f = 0.25 mm/rev and d= 2 mm. Calculate the effect on tool life if speed, feed and depth of cut are together increased by 25% and also if they are increased individually by 25%. Also give your comments. 2 In orthogonal cutting, if the feed is 1.25 mm/rev and chip thickness after cutting is 2mm, determine the following. 1. Chip thickness ratio 2. Shear angle The tool bit has a rake angle of 10º, If shear strength = 600 N/mm2, Width of cut = 10 mm, Cutting speed = 30 m/min, Co-efficient of friction = 0.9 Determine, a. Shear force b. Friction angle c. Cutting force d. Horse power at the cutting tool 3 4 5
Draw a neat sketch of a single point cutting tool indicating its complete geometry on it. What do you understand by orthogonal and oblique cutting? How do they differ from each other? Draw a merchant circle diagram and derive expressions to show relationship among the different forces acting on the cutting tool and different parameter involved in metal cutting.
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Chapter - 2 GEAR AND THREAD MANUFACTURING 1
Classify the generating process for gear cutting? Explain “Gear Hobbing” in detail.
2
Enlist different types of gears and draw gear tooth terminology. With appropriate example discuss plain indexing and compound indexing methods of manufacturing a gear on milling machine.
3
Explain with the help of sketch, principle, types, and applications of gear hobbing.
4
Write short note on Gear finishing process.
5
What are the different types of thread manufacturing processes? Explain in details.
Chapter – 3 JIGS & FIXTURES 1 2 3 4
Distinguish between jig and fixture. State advantages of jigs and fixtures Describe the degrees of freedom for workpiece located in space. Draw a simple sketch to show the 3-2-1 locating principle and explain. List various clamping devices used in jigs and fixtures and explain its working also give their features and application. Sketch different drill bushes useful in drill jigs.
1
List the various types of locating devices used for both Jigs and Fixture and Explain of them with neat sketch. Chapter - 4 PRESSES AND PRESS WORK Write in detail the methods of reducing the cutting forces in press working.
2
Discuss the various types of pilots used in progressive die.
3
1
Sketch and design a progressive die to make a steel washer 30 mm outside diameter with 15 mm hole. From 1.6 mm thick steel sheet. The ultimate shear strength of the material is 320 N/mm 2. Calculate, a. Maximum punch force necessary to blank and punch the washer if both punches operate at the same time, b. Punch and die size for piercing and blanking operation Draw neat schematic diagram of a sectioned view of a blanking die and punch assembly and label on it. Explain the function of (i) Die Block (ii) Punch (iii) Knock out. Draw and discuss following clamping devices (i) Hinged Clamp (ii) Quick Action Nut (iii) Hydraulic Clamp Chapter -5 CONTROLS IN MACHINE TOOLS Describe the essential parts of turret lathe. What is the field of application of turret lathe?
2
Discuss the various types of multi spindle automats.
3
Explain single spindle automates and transfer machines with suitable example.
4
What are automatic transfer machines? Write principle, advantages and disadvantages of it.
5
What is difference between a capstan and turret lathe? Describe in brief with the help of suitable sketch. Chapter -6 NON-CONVENTIONAL MACHINING Define Non-conventional machining? Why do we need these processes? Give classification of the Non conventional processes? What is LASER? Explain LBM.
5
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1 2
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3 4
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Write important functions of dielectric fluid and electrolyte. Also write various types of commonly used dielectric fluid and electrolyte. Describe Ultrasonic Machining (USM) process with neat sketch. Discuss how the following factors effects the material removal rate of USM. (i) Grain Size (iv) Feed force (ii) Frequency (v) Hardness ratio (iii) Amplitude (vi) Abrasive concentration Describe principle of Electrical Discharge Machining (EDM) with figure and state its advantages, limitation and application.
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Seat No.: ________ No.___________
Enrolment
GUJARAT TECHNOLOGICAL UNIVERSITY BE - SEMESTER–VIII EXAMINATION – WINTER 2015
Subject Code: 181903 Date:07/ 12/2015 Subject Name: Production Technology Time: 2:30pm to 5:00pm Marks: 70
Total
Instructions: 4. Attempt all questions. 5. Make suitable assumptions wherever necessary. 6. Figures to the right indicate full marks.
Q.1 (a) Derive various force equations can be derived using Merchant Circle diagram. (b) Draw neat sketch of single point cutting tool showing the six major angles. 07 Explain the need of providing these angles. Q.2
Q.3
Q.3
Q.4
Q.4
Q.5
07
(a) Explain the need of unconventional machining methods. With neat sketch explain ECG method. (b) Explain with neat sketches compound die and progressive die. OR (b) Explain Design of cam for single spindle automat Transfer Machines with suitable example.
07
(a) Explain significance of center of pressure in design of press tools. How it is calculated? (b) How the Presses are classified? Explain the methods of reducing the force requirement in press work. OR (a) List various principles of location and explain the 3-2-1 Principal of Location with neat sketches. (b) What is drilling Jig? Explain the various types of bushes used in drilling jig.
07
(a) Define tool life and explain in brief the factors affecting it. (b) Explain in detail tool dynamometer. OR (a) Discuss following thread manufacturing methods with neat sketch (i) Chasing (ii) Rolling (iii) Tapping. (b) Explain methods of temperature measurement at tool-work interface.
07 07
(a) Discuss the differences between Turret and Capstan lathes.
07
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Q.5
(b) Write important functions of dielectric fluid and electrolyte. Also write various types of commonly used dielectric fluid and electrolyte. OR (a) Explain the different machine tool structures. (b) Explain in brief what you understand by bar type and chucking type machines. *************
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