Effects of oil traction velocity and relative sliding velocity on friction behavior in forming mild steel

A series of experiments was conducted using a rolling-type tribometer to clarify the effects of the oil traction velocity V, average of the friction roll velocity and the workpiece velocity at the inlet to the contact zone, and the relative sliding velocity ΔV during deformation on friction behavior in metal forming. Experiments using mild steel strips with a dull surface for various lubricants showed that the friction stress and friction coefficient decrease with increasing forming velocity especially at high forming velocity. The variation in the friction stress may be due to the increase in ΔV derived from the increase of the forming velocity because the friction stress decreases with increasing ΔV but varies little with increasing V. It was also confirmed that the increase of ΔV promotes flattening of the workpiece asperities.