Numerical simulation analysis of rubber flexible die properties on forming quality of the double-curved part for 6K21-T4 aluminum alloy

The double-curved is the main feature of the sheet metal part, which is mainly used in automobile panels, aircraft skins, high-speed rail car bodies, etc. The forming process can easily lead to the local thinning and springback and seriously affect its forming quality. In this paper, the influence of the shear modulus of the flexible die on the thinning and springback of 6K21-T4 aluminum alloy for double-curved parts was analyzed by the numerical simulation method. Different rubber flexible die were selected for the forming process of the different double-curved parts, and the effect of the shear modulus on the thinning and springback of double-curved parts was obtained. Results show that the thickness reduction of the part formed by the rubber flexible die is reduced by 10.6% compared with that of the rigid punch forming. The maximum effective stress difference can be reduced by 67.4% and the springback can be reduced by 64.8% through optimizing the shear modulus of rubber flexible die.