381. In progressive die (for sheet metal), spring loaded stripper plate is used to clamp the stock until

1. 1. The punch penetrates twice the stock thickness

   
   
   

   2. It removes wrinkles on the product edges

   
   
   

   3. Automatic feeder plate releases it

   
   
   

   4. Punch is completely withdrawn from the stock

   
   
   

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1. View Hint View Answer Discuss in Forum

   Punch is completely withdrawn from the stock

   Correct Option: D

   Punch is completely withdrawn from the stock

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382. Consider a linear elastic rectangular thin sheet of metal, subjected to uniform uni-axial tensile stress of 100 MPa along the length direction. Assume plane stress condition in the plane normal to the thickness. The Young’s modulus E = 200 MPa and Poisson’s ratio μ = 0.3 are given. The principal strains in the plane of the sheet are

1. 1. (0.5, – 0.15)

   
   
   

   2. (0.5, 0.0)

   
   
   

   3. (0.35, – 0.15)

   
   
   

   4. (0.5, – 0.5)

   
   
   

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1. View Hint View Answer Discuss in Forum

   Given E = 200 MPa
   σ_x = 100 MPa
   σ_y = 0
   Principal strain in x-direction
   

   εx =	σx	- μ	σy
   	E		E

   
   

   =	100	- 0 = 0.5
   	200

   
   ε_x = 0.5
   Principal strain in y-direction,
   

   εy =	σy	- μ	σx
   	E		E

   
   

   ⇒ 0 - 0.3.	100	= - 0.15
   	200

   
   (ε_x, ε_y) = (0.5,-0.15)

   Correct Option: A

   Given E = 200 MPa
   σ_x = 100 MPa
   σ_y = 0
   Principal strain in x-direction
   

   εx =	σx	- μ	σy
   	E		E

   
   

   =	100	- 0 = 0.5
   	200

   
   ε_x = 0.5
   Principal strain in y-direction,
   

   εy =	σy	- μ	σx
   	E		E

   
   

   ⇒ 0 - 0.3.	100	= - 0.15
   	200

   
   (ε_x, ε_y) = (0.5,-0.15)

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383. The value of true strain produced in compressing a cylinder to half its original length is

1. 1. 0.69

   
   
   

   2. -0.69

   
   
   

   3. 0.5

   
   
   

   4. -0.5

   
   
   

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1. View Hint View Answer Discuss in Forum

   Engg. strain
   

   (ε) =	Change in Length
   	Original Length

   
   
   True strain = ln(1 + ε) = ln(1 – 0.5) = – 0.69

   Correct Option: B

   Engg. strain
   

   (ε) =	Change in Length
   	Original Length

   
   
   True strain = ln(1 + ε) = ln(1 – 0.5) = – 0.69

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384. A 300 mm thick slab is being cold rolled using roll of 600 mm diameter. If the coefficient of friction is 0.08, the maximum possible reduction (in mm) is_______.

1. 1. 1.92

   
   
   

   2. 1.95

   
   
   

   3. 1.94

   
   
   

   4. 1.99

   
   
   

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1. View Hint View Answer Discuss in Forum

   Maximum possible reduction
   = ∆ H/pass = µ²R
   = 0.08² × 300 = 1.92 mm

   Correct Option: A

   Maximum possible reduction
   = ∆ H/pass = µ²R
   = 0.08² × 300 = 1.92 mm

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385. In a rolling process, the maximum possible draft, defined as the difference between the initial and the final thickness of the metal sheet, mainly depends on which pair of the following parameters?
     P: Strain
     Q: Strength of the work material
     R: Roll diameter
     S: Roll velocity
     T: Coefficient of friction between roll and work

1. 1. Q, S

   
   
   

   2. R, T

   
   
   

   3. S, T

   
   
   

   4. P, R

   
   
   

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1. View Hint View Answer Discuss in Forum

   ∆ h = µ²R

   Correct Option: B

   ∆ h = µ²R

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