Calculation of Average Rolling Force

Q. 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. 15.8mm 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 MN

Q. A cold roll aluminium strip of 1400 mm width from 4 mm to 3.2 mm thickness on a 4 high mill. The diameter of the roll is 450 mm. Plane strain of aluminium at inlet as used is 0.5 and corresponding plane stress is $135N/m{m}^2$. Take the value of $\mu$ as 0.05 and strain at the end of rolling as 0.8 when plane stress is $148N/m{m}^2$. The expression of roll force is given by

$F=\omega \sqrt{R\Delta h}{\sigma }_m(1+\frac{\mu \sqrt{R\Delta h}}{h_b+h_f})N$

where symbols carry usual meaning.

The rolling load will be_____tonne.

1. 296.168