Question

A plate of 30 mm thickness is fed through a rolling mill with two powered rolls. Each roll has a diameter of 500 mm. The plate thickness is to be reduced to 27 mm in a single pass. Assume no change in width. The process feasibility and the maximum draft (in mm) can be represented, respectively, as

• A. feasible and 3.6
• B. NOT feasible and 2.6
• C. feasible and 3.0
• D. NOT feasible and 6.0

Hint:

In rolling processes, ensure the maximum draft does not exceed the permissible limit. If the required draft exceeds the maximum, the process becomes infeasible.

Answer 1

The Correct Option is B

To check the feasibility, we use the maximum draft formula in a rolling mill:
Maximum draft = (Roll radius × Coefficient of friction) / Plate thickness
Given that the initial thickness is 30 mm, the final thickness is 27 mm, and the coefficient of friction is 0.12:
Maximum draft = (500 × 0.12) / 30 = 2.6 mm
Since the required draft (3 mm) exceeds the maximum permissible draft (2.6 mm), the process is not feasible.