Effects of Average Lubricant Velocity and Sliding Velocity on Friction Behavior in Mild Steel Sheet Forming

Abstract

A series of experiments was carried out using a rolling-type tribometer to investigate the frictional dependence on the average velocity of the lubricant V at the contact zone inlet and the relative sliding velocity ΔV between the roll and workpiece during deformation. Experiments using mild steel strips with a dull surface of 0.63 fxm Ra showed that the friction coefficient decreases with increasing forming velocity, especially at high forming velocity. This variation in the friction coefficient may be due to the increase in ΔV derived from the increase of the forming velocity, because the friction coefficient decreases with increasing ΔV but varies little with increasing V. It was also confirmed that an increase of ΔV or a decrease in V promotes flattening of the workpiece asperities.