A 4 mm thick aluminum sheet of width w = 100 mm is rolled in a two-roll mill of roll diameter 200 mm each. The workpiece is lubricated with a mineral oil, which gives a coefficient of friction, µ=0.1. The flow stress (𝜎 ) of the material in MPa is 𝜎 =207+414 𝜀, where 𝜀 is the true strain. Assuming rolling to be a plane strain deformation process, the roll separation force (F) for maximum permissible draft (thickness reduction) is _________ kN (round off to the nearest integer).
Use:
is average flow stress, 𝐿 is roll-workpiece contact length, and ℎ J is the average sheet thickness.