Effect of Sealing Position on Bulge Height in Hydroforming of Aluminum Tubes

In this paper, a new sealing method has been applied to eliminate the friction force between the tube and the die. The new sealing method was experimentally examined in the free bulge test of AA6063 aluminum tubes and necking limit strains, thickness and bulge height of specimens were measured. Results showed that the new sealing method compared to the conventional sealing method improves the material flow to the deformation zone and, therefore, increases the bulge height of aluminum tubes. Finite element simulations of the free bulge test were performed in ABAQUS software under the different process parameters. In these simulations, forming limit curve obtained from the experimental tests was utilized to predict of the necking. Results showed that an increase of friction coefficient, axial feed and initial length tub increases the bulge height of aluminum tubs in the new sealing method compared to the conventional sealing method.