JNTU B.Tech II Semester Examinations, METAL FORMING, Aug/Sep 2008

JNTU B.Tech II Semester Examinations, METAL FORMING

, Aug/Sep 2008

(Production Engineering)

Time: 3 hours Max Marks: 80

Answer any FIVE Questions

All Questions carry equal marks

SET-III

1. (a) State the maximum shear stress criterion and derive it.

(b) Explain why the elastic deformation does not disappear, even after the load

which had caused plastic deformation in polycrystalline materal is relased.

[8+8]

 

2. (a) Explain why is it neded to perform annealing during cold working process.

(b) Draw a typical recrystalization curve representing

ii) % of recrystallization, and

iii) time of annealing. Explain about the curve. [8+8]

 

3. Define hot working, warm working and cold working.Discuss the relative features

of hot work and cold work for Al, Pt and Molybdenum considering melting point,

brittleness and oxidation behaviour. [16]

 

4. (a) Explain the differeces between

i. drwing and

ii. deep drawing

(b) Expalin why normal anisotrophy is important in determining the deep drwawability of a material . [8+8]

 

5. (a) Distinguish between press forged and drop forged components.

(b) Discuss the forging process in plane strain condition.

(c) A 13kN power-forging hammer has a total nominal energy of 47 kJ. If the

blow efficiency is 40 percent and the forging load builds up from P/3 at the

beginning of the stoke to P at the end of the stroke, what is the total forging

load for

i. a stroke of 5mm

ii. a stroke of 15mm. [6+4+6]

 

6. (a) Explain the following:

i. Roll forming

ii. Tandum mill

iii. Angle of nip

iv. No slip angle

v. Redundant work

(b) What is the effect of presence of front and back tensions in rolling load?

Explain. [12+4]

 

7. (a) Calculate the force required in extruding a copper alloy at 7500C, if the billet

diameter is 80 mm and the extrusion ratio is 20.

(b) Explain the term ‘efficiency of a forming process’ in terms of energy consumed.

(c) What is the significance of grain size control for metal forming? [6+5+5]

 

8. (a) Explain about the residual stresses in rods, wires and tubes drawn.

(b) Discuss the effects of the following on maximum possible reduction in wire

drawing with no back tension.

i. Cone angle

ii. Friction [10+6]

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