Experimental investigation of contact conditions in tube end forming process by tapering

Abstract

This paper presents the experimental investigation of force and influence of contact conditions in the thin-walled tube end forming process by tapering. Based on the set requirements numerical simulation is performed within which two tubes are analyzed. Tubes are of the same material, thickness and length but have different diameters. Based on the results of FEM analysis, forces for the tube end forming are estimated and the appropriate equipment for experimental investigation of force is adopted. Dies are made without heat treatment with two different quality of surfacing. Influence of contact conditions (friction coefficient) is investigated for three different cases: without lubrication – dry friction, lubricant for cold forging and cutting fluid – coolant, thus making a total of six different contact conditions. The investigated contact conditions in the circular tube end forming process by tapering have influence on the force reduction of approximately 10%, which is particularly important for the thick walled tubes, since forces are then much larger.