Abstract:

According to the characteristics that the multi-gripper stretch forming machine can realize the flexibility of clamping and stretching， finite element models of rectangular and trapezoidal sheet metal were built for surface parts of trapezoidal projection plane， and numerical simulations of different transition zones for rectangular and trapezoidal metal sheets were conducted. The results showed that with the decrease of the maximum length of the transition zone， the conformability of the sheet metal to the forming die was increased， the forming force together with the maximum strain of the formed parts decreased while the strains and thickness of the effective forming zone distributed more uniformly and the formability was much better. Stretch forming experiments were done for the surface part of trapezoidal projection plane， and the experimental results were coincident with the numerical simulation results， which proved the validity of simulation. The multi-gripper stretch forming machine can reasonably choose the transition zone shape according to the shape of forming die， which improves forming quality and reduces the material and stretch forming costs.

Key words: plasticity processing, sheet metal forming, stretch forming process, numerical simulation, transition zone