# JNTU question papers III B.Tech Supplimentary Examinations, Metal forming – Aug/Sep 2008

JNTU III B.Tech Supplimentary Examinations, Aug/Sep 2008

Metal forming

(Production Engineering)

SET-IV

1. (a) Derive an expression for strain tensor generally used in three dimensional stress system.

(b) Why True stress – strain curve is called Flow Curve? Give reasons. How do you indicate Flow curve mathematically?

2. (a) Discuss the concept of ‘Strain Aging’. Explain its effect in flow curve of a low carbon steel with a sketch.

(b) Define the following:

i. Dislocation climb

ii. Cross slip

iii. Jogs in dislocation

iv. Perfect and partial dislocation

3. (a) Explain the process of bending operation? Discuss various types of bending with neat sketches.

(b) How can spring back be offset? Explain the factors influencing spring back. What is its application and relative merits.

4. (a) Sketch and explain the working of a Compound die. Indicate various elements in it.

(b) Sketch and explain the constructional details of Hydraulic press and mention its salient features.

5. (a) Derive an equation to calculate Extrusion Load.

(b) Discuss the common methods of extrusion processes with sketches.

6. (a) Differentiate between ‘Surface Cracking’ and Internal Cracking of the extruded product. How they can be explained? Mention methods of eliminating them.

(b) Name the important process variables in the drawing of rod and wire. Discuss briefly.

7. (a) Distinguish between Open Die and Closed Die Forging. Illustrate with examples. Give suitable sketches. What is Multi-Impression Die ? How it plays a role in Forging.

(b) Discuss various parameters to be considered in the design of forging dies and explain their effects on quality and finish of the components.

8. (a) Explain the principles and theory of Rolling with governing equations. How seamless tubes are manufactured ?

(b) Deduce the differences between Forward slip and Backward slip. How Front tension differs from Back Tension. In what way it affects Rolling ?