Investigation into the effect of pre-bulging during hydromechanical deep drawing with uniform pressure onto the blank

Many parameters influence the process of sheet hydroforming, but the key one is the pre-bulging. Pre-bulging includes two parameters: pre-bulging height and pre-bulging pressure, which influence the forming process significantly. In this paper, based on the proposed hydromechanical deep drawing with uniform pressure onto the blank, the effect of pre-bulging on the forming is investigated experimentally and the needed process windows for the pre-bulging pressure and the pre-bulging height are built by using pure aluminum and aluminum alloy. Finally, FEM is used to analyze the forming process to explain some results which were found in the experiment.