Finite Element Simulation of Multi-gripper Flexible Stretch Forming

Abstract

Multi-gripper flexible stretch forming is a novel sheet metal forming process aimed at improving the conformability of sheet metal to forming die, material utilization and forming quality of sheet metal. Straight jaws in traditional stretch forming machines are replaced by a pair of opposed clamping mechanisms movable relative to each other during the forming process. In the present study, a wave-like surface part was selected as the study object, and the forming processes of traditional stretch forming and multi-gripper flexible stretch forming were performed using a commercially available finite element analysis software to show their influences on conformability of sheet metal. In addition, three levels of transition lengths in multi-gripper flexible stretch forming were chosen to investigate their influence on forming results. The simulation results show that multi-gripper flexible stretch forming would result in an easier conformability of sheet metal than traditional stretch forming. It is also found that the sheet metal can be formed without a transition length, which could significantly improve the material utilization. In addition, the simulation results show that a shorter transition length would result in a smaller maximum strain in the forming zone, which may provide a useful guidance on choosing the transition length of sheet metal.