Pressure generated in the hydraulic-pressure augmented deep-drawing process

摘要

A recently developed hydraulic-pressure augmented deep drawing process to draw cups at largedraw ratios is introduced briefly. A hydraulic pressure proportional to the punch force is generated inthis process, the blank-holding force also being provided by this hydraulic pressure. In addition, thehydraulic pressure is applied on the periphery of the flange of the cup, the drawing being performedin a simultaneous push-pull manner making it possible to achieve higher draw ratios than thosepossible in the conventional deep-drawing process. The process has other advantages such as theautomatic coordination of the punch force and the blank-holding force, low friction between theblank and the tooling as the high-pressure liquid lubricates these interfaces, and the elimination of theneed for a complicated control system. The deep-drawing process can be easily carried out on asingle-action press without the need for a cushion. The principle of the process is introduced in thispaper. Experiments were conducted in the drawing of cups of 36 mm diameter at draw ratios of up to3.11 using annealed aluminum blanks. Using a process model, a finite-element analysis of the processwas carried out. The hydraulic pressures measured in the experiments are compared with thosecalculated using a simple analytical method and those from the finite-element analysis.