Modeling and numerical simulation of multi-gripper flexible stretch forming process

Abstract

Multi-gripper flexible stretch forming (MGFSF) is a recent technological innovation of sheet metal forming process. Straight jaws in traditional stretch forming machines are substituted for a pair of opposed clamping mechanisms movable relative to each other during the forming process. In this paper, spherical part is selected as the study object, and numerical simulations of the MGFSF process under two representative loading paths of horizontal-vertical (HV) loading path and horizontal-tilting-vertical (HTV) loading path have been carried out using a commercially available FEM software (ABAQUS). Four levels of horizontal forces in HV loading path are selected to investigate their influences on strain and forming error distributions of the simulated parts. In addition, four levels of tilting forces in HTV loading path are also taken into consideration. The simulation results reveal that HV loading path would result in a larger strain but a smaller forming error in the forming zone. In contrast, HTV loading path would result in a smaller strain but a larger forming error in the forming zone. Finally, experimental validations are conducted on self-developed apparatus, and the experimental results show a good correlation with the simulation results.