Improvement in Drawability by Hydraulic Counter-Pressure Deep Drawing

Hydraulic counter pressure deep drawing is a process for producing cup shaped parts with the assistance of a pressurized fluid. In the present work a complete experimental set up has been designed and fabricated to conduct hydro-mechanical deep drawing on a 315 tonne hydraulic press. A comparison was made between conventional and hydro-mechanical deep drawing using low carbon steel sheets (EDD grade) of 1.00 mm sheet thickness. Limiting draw ratio (LDR) has been determined experimentally by using blanks of various diameters. Effect of counter pressure on LDR was also studied. Pre-bulging height was also measured at different chamber pressures and LDR was theoretically predicted. It was found that by hydro-mechanical deep drawing higher drawabllity, more uniform thickness distribution and better surface finish were obtained when compared to conventional deep drawing.