Flattening of surface grooves in cold flat rolling

In sheet rolling, surface deforms more than bulk interior so that surface asperities are flattened. However, it is still not easy to predict the roughness of the sheet after rolling. Copper sheets having artificial triangular grooves running either in the transverse or the rolling direction were cold-rolled. Initial contact ratio was varied by changing pitch between two adjacent grooves. With increasing reduction in thickness by the rolling, depth as well as width of grooves decreases, meanwhile contact ratio between the sheet and the roll increases. The change in contact ratio agrees with 2D analytical solutions when the initial contact ratio is high. It is also found that grooves running in the transverse direction are more flattened than those in the rolling direction. (C) 2014 The Authors. Published by Elsevier Ltd.