Investigation into Manufacturing of Very Long Cups by Hydromechanical Deep Drawing and Ironing with Controlled Radial Pressure

Abstract

High-quality cups of deep drawing ratio of more than four cannot be simply drawn by conventional drawing and redrawing process. In the present study, after the first deep drawing process, subsequent hydromechanical reverse redrawing with controlled radial pressure and final ironing to control the thickness and outer surface appearance are employed. In order to increase the deep drawing ratio much more than four, the radial pressure is controlled independently of the chamber pressure and thus an optimum forming condition can be found by varying the radial pressure. The final ironing process ensures the fine surface quality as well as improved deep drawing ratio without inducing any forming defect such as slight puckering and surface waviness. The process has been subject to finite element analysis by using the rigid-plastic material modeling considering all the frictional conditions induced by the hydrostatic pressure. The comparison of the computation with the experiment has shown that the finite element modeling can be conveniently employed for the design of the process with reliability from the viewpoint of formability. © 1995 CIRP.