Question

In a cold rolling process without front and back tensions, the required minimum coefficient of friction is 0.04. Assume large rolls. If the draft is doubled and roll diameters are halved, then the required minimum coefficient of friction is .............

Hint:

In cold rolling, the coefficient of friction plays a significant role in determining the process efficiency. Changes in draft and roll diameter will directly affect the required friction for optimal rolling.

Answer 1

The minimum coefficient of friction \( \mu_{{min}} \) for a cold rolling process is related to the draft and roll diameters. The required coefficient of friction depends on the specific conditions of the rolling process, and it typically scales with the square root of the diameter ratio and the draft ratio. Given the relationships:
- The draft is doubled, so the coefficient of friction would typically increase.
- The roll diameters are halved, which would also cause an increase in the required coefficient of friction.
From empirical formulas used in rolling processes, we know that the required minimum coefficient of friction typically increases when both the draft is doubled and the roll diameter is halved. Therefore, the required coefficient of friction in this case is: \[ \mu_{{min}} = 0.08. \]