Hydromechanical deep drawing

An experimental investigation on the control of process parameters for the hydromechanical deep drawing of mild steel and an aluminium alloy with special attention to control of the blank holder force (BHF) is carried out. The effect of the counter pressure in the hydromechanical deep drawing process is investigated in combination with different constant levels of the BHF. Differences in strains obtained for the conventional and hydromechanical deep drawing process as well as process limitations are presented. An attempt to improve partial quality by control of the packing effect between the blank and draw die by varying the blank holder force according to the punch force have been explored. A closed-loop control for the BHF is implemented, but no significant effect could be found due to limitations of the BHF range and delayed response of the pneumatic-based BHF system.