Deep drawing of a thin hemispherical cup using a novel die without a blank holder: experimental and numerical investigations

In this paper, deep drawing of a thin circular blank into a perfect hemispherical cup at room temperature, using a die without a blank holder, is experimentally and numerically studied. Eliminating the blank holder may result in a defective product due to a different failure mode, such as wrinkling or puckering. Hence, based on the previous studies, it is not recommended to eliminate the blank holder in the deep drawing process. An improved die profile has been proposed to compensate for the disadvantages that may arise due to blank holder elimination. The proposed new profile is based on a multi-arc curve. For this purpose, ABAQUS FE simulation was utilized to determine the proper die profile. Then, in order to practically investigate the proposed profile, the die was manufactured and used to carry out experimental tests. Thin circular blanks of St13 and Al1050 were drawn into the hemispherical cups in the experiments, using the proposed die without a blank holder. To validate the simulations, numerical and experimental force–displacement curves were compared. A very close agreement was observed, which evidently shows the validity of the simulation results. The perfect cups drawn by the proposed die showed that it is possible to draw a thin circular blank into a perfect hemispherical cup at room temperature, using a die without a blank holder, if the die profile is properly designed.