Exam Paper On Design of Machine Tools
Exam Paper On Design of Machine Tools
Exam Paper On Design of Machine Tools
Answer FIVE questions, taking ANY TWO from Group A, ANY TWO from Group
Band All from Group C. Figures in the bracket indicate full marks.
Group A
Q. 1 (a) Basic definition wise how is 'Machine tool' different from 'Mechanism' and
'Machine'? (4)
(b)How is a centre lathe specified? (4)
(c) Name the various mechanisms that are used to convert rotary motion into linear
or translatory motion and give examples of application of those different
mechanisms in machine tools. (10)
(d) Why are almost all the lathes made horizontal and their Centre height from the
floor is also more or less same and is around 1.0 metre. (2)
Q. 2 (a) Why are Centre lathes provided with a speed gearbox and a feed gearbox?
(4)
(b)Draw a feasible Ray diagram and the corresponding gear layout for a speed
gearbox to be used in a Centre lathe having 12 spindle speeds ranging from 20 rpm
to 900 rpm. (12)
(c) Show by a block diagram the major procedural steps that are followed in
sequence while designing a machine tool. (4)
Q. 3 (a) Draw schematically the kinematic diagram of a Centre lathe or a milling
machine and briefly state the working principle of that machine tool (12)
(b) Why and how the stroke length of a shaping machine is varied (or adjusted)? (4)
(c) Why is lathe spindle made hollow'? (4)
Q. 4 (a) What factors need to be considered during designing the body or structure
of any machine tool? (4)
(b)Why is grey cast-iron preferably used to make lathe beds? (4)
(c) Draw a cross sectional view of the bed of a medium duty Centre lathe and state
the functions or purposes of the different features (surfaces) shown in that cross
sectional view of the lathe bed. (8)
(d)How is the table-feed controlled in a grinding machine having hydraulically
driven worktable? (4)
Group B
Q. 5 (a) Sketch a centre lathe spindle showing its mounting in two bearings at its
two ends and three gears of different size being rigidly mounted on that spindle.
(b)What factors need to be considered while designing a lathe spindle for strength?
(4)
(c) Why and how the friction in between the worktable (slide) and the bed (guide) is
reduced in heavy-duty machine tools. (4)
(d)State the working principle and the relative advantages of recirculating balls type
feed screws being used in modern machine tools like CNC milling machines. (4)
Q. 6 (a) What are the effects and possible causes of vibration in machine tools? (8)
(b)What does machine tool chatter mean? How such chatter develops and can be
controlled? (4)
(c) State the purposes of mounting machine tools on proper foundations. (4)
(d)What features and characteristics of a machine tool are checked and measured
during its:
(i) Geometrical test,
(ii) Kinematic test,
(iii) Idle run and
(iv) Full load-running test? (4)
Q. 7 (a) How can vibration in centre lathes be reduced without sacrificing
productivity and product quality? (4)
(b)Compare flexible automation with fixed automation with respect to their basic
working principle in machine tools, advantages, limitations and applications. (8)
(c) Usually when, where and by whom machine tools are thoroughly tested? (4)
(d)What are the differences between Machine tool inspection and Machine tool
testing?' (4)
Q. 8 (a) With the help of a suitable sketch briefly describe the working principle of
hydraulic copying lathe or copy milling machines. (8)
(b)State the purposes of incorporating automation in machine tools. (4)
Group B
Q. 5. (a) Discuss, with neat sketches, various types of sleeve bearing used in a lathe.
(4)
(b) Discuss the slideways with hydraulic relief. What are its characteristics? (5)
(c) Draw a neat sketch of the cam- controlled automatic system used in machine
tools. Explain its working principle. (5)
(d) Describe the acceptance tests for lathes. (6)
Q. 6. (a) Explain in brief, with sketches, various methods used for adjustment of
clearances in slideways. (5)
(b) Draw a neat sketch of the speed changing mechanism of a jig boring machine
and explain its principle of operation. (5)
(c) Discuss in brief the effect of vibration on the cutting conditions. (5)
(d) Explain various instruments required for acceptance tests. (5)
Q. 7. (a) What do you mean by aerostatic slideways? Discuss briefly its operating
principle along with its design aspects. (6)
(b) Derive an expression to find out the diameter of the spindle subjected to
combined bending and twisting. (6)
(c) Explain briefly the design principles of push buttons with a sketch. (4)
(d) What are the various sources of vibrations? Explain any two of them briefly. (4)
Q. 8. (a) Explain in brief the importance of adaptive control system.
Draw a block diagram of a process optimization adaptive control system and explain
its principle of operation. (6)
(b) Explain briefly the stick slip motion in guides and its effect on the performance
of machine tools. How is the stick slip motion minimized? ( 6) .
(c) Discuss in brief, with sketches, the design principles of toggles. (4)
(d) Discuss the hydrodynamic slideways. Find out me hydrodynamic force and
maximum load carrying capacity in a wedge of infinity width. (4)
Group C
Q. 9. (A) Match the following:
Machine Tool Common Ratio,
(i) Heavy duty machine tools and automats (a) 126
(ii) Large- to- medium size general- purpose machine tools and automats (b) 1
41
iii) For milling machines, the drive and feed motions are:
(i) The coefficient of efficiency of belt drive with flat belt is
(a) 098 (b) 096
(c)095 ( d) 090.
(ii) The piston pumps in hydraulic transmission system is used for pressures up to
(a) 250 N/cm2 (b) 1000 N/cm2
(c) 1400 N/cm2 (d) 1800N/cm2.
List II
(a) Generatrix
(b) Grey cast iron as spheroidal graphite iron
(c) Directrix
(d) C-1045 steel (1 x6)
Cutting motion
Hollow-heavy duty spindles
(iii) Tapered roller bearings
(iv)
(v)
List I
(1) Cylindrical roller bearings
(ii) Feed motion
(e) Both radial and axial loads
(vi) Normal accuracy spindles (j) Radial loads only.
(C) Choose the correct answer for the following: (1 x 10)
(iv) Medium- to-small size general- (d) 112.
purpose machine tools
(B) Match the following:
Common Ratio, rp
(a) 126
Group A
1. (a) State the essential requirements of machine tools. Outline various factors
affecting the selection of materials for machine tools.
(b) What are the important elements of mechanical transmission? Explain each one
of them briefly?
2.(a) How do you select range of speeds in the design of gear boxes?
(b) What is support-drive? Explain.
3. (a) Discuss advantages .and disadvantages .of hydraulic regulation of machine
tool drives. Describe the working of a hydraulic drive unit for rotary motions.
(b) What is the effect of stiffness arrangement on the bending and torsional stiffness
of box-type structure?
4. (a) What are the aspects to be considered while selecting welded vs. cast structure.
What is the importance of combination of guide and guideway materials?
(b) Define stress concentration factor. State the methods to reduce effect of stress
concentration.
Group B
5. (a) Sketch and explain the tandem arrangement of spindle bearing of a horizontal
boring machine?
(b) What do you understand by the term 'stick-slip vibration' in machine tools? What
is the purpose of scraping the cast iron guide and guideways after finish grinding
operation.
6. (a) Why is preloading of spindle support bearing done? State the method of
preloading radial ball bearing.
(b) State the procedure for selecting ball bearing from manufacturer's catalogue.
7. (a) List the applications of hydraulic and pneumatic actuators and controls in
machine tools.
(b) Distinguish between steady load and cyclic load. Mention applications where
these loads are occurred.
8. Write short notes on the following:
(a) Ergonomics applied to machine tools
(b) Acceptance tests of machine toots
Group C
9. Write the answer for the following in brief:
(i) Classify design work.
(ii) Discuss basic requirements of a good machine tool design.
(iii) What are the factors to be considered in the selection of the axis feed drive of a
machine tool ?
(iv) Name four mechanical stepless drivers.
(v) Mention any three mechanisms that can convert rotary motion into translation.
(vi) What are the requirements of a machine tool structure?
(vii) How do you express life of bearing?
(viii) What are the slideway profiles?
(ix) What is meant by dynamic rigidity in terms of machine tool design?
(x) What are the feed rate-dependent errors?
Group A
3 (a) Discuss various methods of increasing rigidity of 1 machine elements.
(b) Differentiate between connection diagram and flow diagram for a gear box
having four output speeds.
Differentiate between the following: 4x5
(a) Static and dynamic stiffness
(b) Stepped and step less drive
(c) Goodman's diagram and modified Goodman's diagram
(d) Guideways and slideways.
Group B
5. (a) Discuss design of machine tool spindle subjected to combined bending and
twisting.
(b) Explain the following :
(i) Stick slip motion in guides
(ii) Chatter in machine tools
6. (a) Discuss objects and procedure for acceptance tests for machine tools and
explain any two instruments used for it.
(b) Describe various elements of control systems for machine tools.
7. (a) Explain standard acceptance test charts for a lathe.
(b) Describe aesthetic and ergonomics as applied to machine tools with suitable
examples.
8. (a) Discuss the effect of vibration on machine tools.
(b) Explain the force analysis of lathe guideways.
Group C
9. Explain the following in brief:
(i) What is kinematic structure of machine tool?
(ii). Explain speed structure-analysis.
(iii) Differentiate between rigidity and. compliance of a machine tool.
(iv) For what type of loads bearings are designed? Explain.
(v) Explain the application of hydrostatic bearings.
(vi) What is ray diagram?
(vii) Explain waviness meter.
(viii) What is modular design?
(ix) Describe the purpose of machine tool spindle,"
(x) Name the sources of machine tool vibrations.
MC 424/PR414 (i50'9)
DESIGN OF MACHINE TOOLS
Group A
1. ( a) Classify working motions ~ a machine tool with neat sketches.
(b) Explain important elementary transmissions being used in machine tools for
transforming rotary motion into translator motion.
Group C
9. Answer the following in brief:
(i) Classification of machine tools
(ii) Required properties of materials for machine tools
(iii) Elements of hydraulic transmission
(iv) Aim of feed rate regulation
(v) Choice of different sections of machine tools structures
(vi) Functions of machine tools control systems
(vii) Standardization of machine tools
(viii).Chatter in machine tools
(ix) Factor influencing the dynamic stability of machine tools
(x) Advantages of modular design.