Hydraulic-pressure-enhanced cup-drawing processes—an appraisal

Hydraulic-pressure-enhanced deep drawing techniques generally increase the depth-to-diameter ratio possible in cup drawing. Draw ratios of up to 3.5 have been achieved by some of these processes. Phenomena being used in these processes include a peripheral push to aid the draw force, hydraulic pressure tightly holding the wall of the cup against the punch and fluid lubrication of the die radius and the flange of the cup being drawn. Various aspects including the principles underlying these are presented and discussed in this paper.