Curling of Sheet in Asymmetric Rolling Investigated by Profile Measurement of Partly Rolled Sheet

Abstract

The curling of a sheet in cold asymmetric rolling was investigated experimentally by interrupted rolling. Influences of speed difference as well as entry table height were studied. The upper and lower profiles of the aluminum sheet obtained by interrupted rolling were measured by a laser profilometer. The contact lengths on both upper and lower surfaces L_U and L_L were detected from the profiles. The curvature radius of sheet was calculated from the curling profiles. Under differential-speed rolling, the sheet curled to the slower roll side at low reduction in thickness, while it curled to the faster roll side at higher reduction. Meanwhile, L_U on the faster (upper) roll surface was longer than L_L on the slower (lower) roll surface at low reduction. On the other hand, L_U was shorter than L_L at higher reduction in thickness. It is found that the ratio of contact length L_L/L_U is correlated with the curling direction in the differential-speed rolling. If L_L/L_U < 1, the sheet curls towards the slower roll side, while the sheet curls towards the faster roll side in case of L_L/L_U > 1.