Download GTU BE/B.Tech 2018 Winter 7th Sem New 2172108 Metal Working Processes Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER-VII (NEW) EXAMINATION - WINTER 2018

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Instructions:

1. Attempt all questions.

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2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.

MARKS

Q.1 (a) Classify metal forming processes. 03

(b) Differentiate between cold and hot working. 04

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(c) What is Stress-Strain diagram? Draw sample Stress-Strain 07
diagrams for mild steel and cementite.

Q.2 (a) Multiple Choice Questions: 03

1. A three high rolling mill consists of three rolls placed one
   above the other. Which of the following statement is
   

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   correct?
   1. The upper and middle rolls rotate in the same
      direction whereas the bottom roll rotates in
      opposite direction.
   2. The upper and bottom rolls rotate in the same
      direction whereas the middle roll rotates in
      

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      opposite direction.
   3. The middle and bottom rolls rotate in the same
      direction whereas the upper roll rotates in opposite
      direction.
   4. All the upper; middle and bottom rolls rotate in the
      

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      same direction.
2. A moving mandrel is used in
   1. Wiredrawing
   2. Tube drawing
   3. Metal cutting

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   4. Forging
3. Cold working of metal increases
   1. Tensile strength
   2. Yield strength
   3. Hardness

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   4. All of the above

(b) Briefly explain flow curve for material. 04

(c) Draw Tresca’s yield criteria in two-dimensional stress state and 07
write yield condition for each side of the diagram.

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OR

(c) Find the relationship between von Mises’ yield function and the 07
shear stress on octahedral plane for a state of stress given by three
principal stresses.

Q.3 (a) Name at least six components that are manufactured by extrusion 03

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(b) What are the benefits of hydrostatic extrusion process? 04

(c) Explain briefly the variables that affect the metal flow in direct 07
extrusion process. Also discuss the role of lubricant.

OR

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Q.3 (a) Why small diameter rolls should be used for rolling very thin 03
sheets?

(b) What is the effect of the following factors on the rolling load? 04

1. The co-efficient of friction,
2. Forward and backward tension.

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(c) Discuss rolling defects with causes and remedies. 07

Q.4 (a) What is the function of flash in forging. 03

(b) Give the effect of forging on microstructure in comparison with 04
machining and casting.

(c) Compare and contrast open die forging and close die forging. 07

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OR

Q.4 (a) Explain briefly deep drawing process with figure. 03

(b) With neat sketch discuss stretch forming. 04

(c) Write short note on workability. 07

Q.5 (a) Discuss the effect of strain rate on metal working processes. 03

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(b) What are the common defects observed in wire drawing process? 04
Explain any one in detail.

(c) With neat sketch explain the types of tube-drawing processes. 07

OR

Q.5 (a) What are the required properties for die selection? 03

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(b) Define: 04

1. Bloom,
2. Billet,
3. Slab,
4. Strip.

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(c) Explain recovery, recrystallization and grain growth with structure 07
property relationship graph.

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