Improvement of Lubrication in Deep Drawing by use of a Die with a Slightly Inclined Face

Abstract

Using a specially designed die with a very slightly inclined face, the punch load is decreased to a lower level than that for the usual flat die. This is because the lubricant trapped on a slightly inclined die face enters on the die radius in the course of the punch stroke, so that friction on the die profile decreases. The punch penetration, at which point the decrease of the punch load starts, can be estimated by calculating the volume of lubricant initially trapped and the change in the intervening space between the die face and the deforming flange during the press. The increase in the limiting drawing ratio (LDR) is brought about by the decrease of maximum punch load, and it depends on the inclination of the die face. The experimental results show that the LDR is increased by about 0.15 at the optimum inclination.