JNTU previous year question papers
JNTU III B.Tech Supplimentary Examinations, Aug/Sep 2008
1. Explain the terms:
(a) “True Stress” and “True Strain”. How they differ from the concepts of Engg. Stress and Engg. Strain
(b) Discuss the relationships between
i. True stress and Engineering stress
ii. True strain and Engineering strain
2. (a) Discuss Frank – Read mechanism of generating of dislocations.
(b) How Taylor’s Classical theory forms basis for Work hardening. Discuss.
3. (a) Differentiate between Notching, Lancing and Slitting.
(b) Derive an expression for diameter of a smallest hole that can be punched.
4. (a) Why clearance is required between Die and Punch. List out factors influencing ’clearance’. How the progressive tool is used for making washers ? Explain with a sketch.
(b) Differentiate between Open Frame and Closed Frame presses. Discuss in detail with sketch. What are the advantages and limitations of open frame press over closed frame press.
5. (a) Describe a basic extrusion process and indicate elements in it. Sketch some typical cross-sections that are extruded.
(b) Discuss the effects of deformation speed, die materials and lubricants in hot and cold working processes.
6. (a) Why is lubrication difficult in Wire Drawing? Explain any one lubricating method that is generally employed in Wire Drawing.
(b) What are the various materials used for making wire drawing dies? Explain the application of each of them.
7. (a) Sketch and describe the various sequence of operations in forging of an automobile connecting rod.
(b) Discuss various forging defects mentioning reasons and remedies. Suggest suitable methods of reducing them in forged components?
8. (a) Explain the effect of ’Back Tension’ on Rolling process. Discuss its application with the help of ’Friction Hill’. How the ’forward’ and ’backward slips’ will be explained and its role in Rolling?
(b) Calculate rolling load if steel sheet is hot rolled to 30% from thick slab using 800 mm dia roll. Slab is 40 mm wide. Assume coefficient of friction is 0.3. Plain strain flow stress is 138N/mm2 at entrance and 270N/mm2 at exit. In the above problem, what would be load if the sticking Friction occurs?