Manufacturing Process 3 - Dec 2013

Mechanical Engg. (Semester 5)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks. 1 (a) How the metal working processes are clasified? Explain.(6 marks) 1 (b) Define re-crystallization. Distinguish hot working from cold working.(6 marks) 1 (c) Derive an expression for the following with respect to yield criteria for ductile material:
i) Von-Mises or distortion energy criteria
ii)Fresca or maximum shear stress criteria.(8 marks) 2 Explain the following parameter which affects the metal working process:
i)temperature ii) strain rate effects
iii) hydrostatic pressure iv) deformation zone geometry(20 marks) 3 (a) Explain with sketch the procedural steps involved in forging operation.(6 marks) 3 (b) A solid cylindrical slug made of stainless steel is 150 mm diameter and 100 mm height. It is reduced in height by 50% at room temperature by open die forging with flat dies. Assume \mu as 0.2 and flow stress as 1000MPa, calculate forging force at the end of the stroke.(6 marks) 3 (c) Derive an expression for slab analysis to determine the mean pressure for closed die forging.(8 marks) 4 (a) Explain with sketch any three types of rolling mills(9 marks) 4 (b) Derive an expression to determine the roll force and power required in rolling operation.(6 marks) 4 (c) Determine the maximum possible reduction for cold rolling a 300mm slab when \mu is 0.08 and the roll diameter is 600 mm. What is the maximum reduction on the same mill for hot rolling when \mu is 0.5?(5 marks) 5 (a) Explain with sketch the wire drawing and rod drawing operations.(8 marks) 5 (b) Determine the drawing stress to produce 20% reduction in a 10 mm stainless steel wire. The mean flow stress \bar{sigma } is given as 637 Mpa. The die angle is 12° and the \mu is 0.09. Also determine the power required to draw when the wire is moving through the die at 3m/sec.(6 marks) 5 (c) Explain with sketch any two methods of tube drawing(6 marks) 6 (a) Explain with sketch the direct extrusion and indirect extrusion processes.(6 marks) 6 (b) Explain with sketch the following extrusion process.
i) Cold extrusion ii) Hydrostatic extrusion and iii)Impact extrusion(9 marks) 6 (c) Explain in detail the deformation, lubrication and defects in extrusion.(5 marks) 7 (a) Explain with sketch the progressive die and combination die in sheet metal formatting.(6 marks) 7 (b) Explain with sketch the following operations in sheet metal forming:
i)Deep drawing ii) Stretch forming iii) Rubber press forming.(9 marks) 7 (c) Mention defects in sheet metal formed parts.(5 marks) 8 (a) Explain with sketch the following high energy rate forming methods:
i) Explosive forming ii) Elctro hydraulic forming iii) Electromagnetic forming.(12 marks) 8 (b) Expalin different steps in powder metallurgy process.(8 marks)