IMPROVEMENT OF DEEP DRAWABILITY BY RADIALLY PRESSURIZED FLUID

Developments in the automobile and other sheet metal industries demand continuous improvements in the deep drawing processes. The areas of i mproving deep drawing processes include higher forming limits so that much deeper products can be obtained with less power consumption. In t his paper, the idea of applying hydraulic pressure in the radial direc tion on the periphery of the blank is theoretically analyzed. This rad ial pressure is generated due to the punch movement within the fluid c hamber and is directed through a by-pass to the blank periphery. The p roblem is solved for a work hardening material using the finite differ ence method. The stress and strain distributions in the Range of the s hell are determined and the limiting drawing ratio is calculated at th e instant when the strain in the thickness direction reaches a critica l value. This critical value is assumed to be the strain hardening exp onent of the drawn material. The results show significant increase in the limiting drawing ratio as the radial pressure increases.