ANALYSIS OF THE PROCESS PARAMETERS INFLUENCE ON THE CHANGE OF MEAN CONTACT PRESSURE IN IRONING PROCESS

Friction that occurs in metal forming processes is significantly different from the friction in mechanical joints. Specific pressures in deep drawing with thinning of the wall thickness that occur on the contact surface between the deformed metal and the tool are very high and considerably exceed the yield stress of the workpiece. As a result of such high pressures there are significant changes in the friction conditions, the efficiency of the lubrication is reduced (the lubricant layer breaks and a direct contact of the surfaces occurs) and the wear process is intensified. This paper shows the analysis of the influence of different process parameters (the die angle, lubrication on die and punch, the punch surface roughness, tool material, etc.) on the mean contact pressure based on performed experimental tests on the model.