A copper strip of 200 mm width and 300 mm thickness is to

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A copper strip of 200 mm width and 300 mm thickness is to be rolled to a thickness of 295 mm. The roll of radius 300 mm rotates at 100 rpm. The average shear strength of the work material is 180 MPa. The roll strip contact length and the roll force are

1. 15.8 mm and 0.569 MN
2. 18.97 mm 0.683 MN
3. 38.73 mm and 1.395 MN
4. 38.73 mm and 2.09

Correct Option: C

h_i = 300 mm h_f = 295 mm
Δh = h_i – h_f = 5 mm
R = 300 mm, N = 100 rpm.
τ_{avg_{= 180 MPa
Roll strip contact length
L = √ΔhR
= √5 × 300 = √1500 = 38.73 mm
Rolling force = τ_{avg_{.L_f × width = 1.394 MN}}}}