Lubricant behavior trapped within pockets on workpiece surface in lubricated upsetting by means of direct fluorescence observation technique

摘要

It is important to understand the trapping behavior of liquid lubricant within pockets on the workpiece surface at the tool-workpiece interface during metal forming in order to characterize and qualify the surface structure of workpiece. Therefore, it is tried to measure the lubricant behavior trapped within pockets in lubricated upsetting. In order to measure the lubricant behavior, a direct fluorescence observation technique has been developed, consisting of a direct observation method and a conventional fluorescence method. The lubricant behavior and the pocket geometry are measured by means of the technique. The volume of the oil pocket decreases with increasing reduction in height. From these results, it is confirmed that the lubricant trapped within the pockets is permeated into the real contact area. The volume change of the oil pocket depends on the position on the end surface of workpiece and the geometry of cylindrical specimen.