Numerical simulation of multi-point stretch forming and controlling on accuracy of formed workpiece

Abstract

A finite element model was built for the sheet metal multi-point stretch forming (MPSF), and the model was applied to the MPSF of a typical part. The numerical simulation of the MPSF for a saddle and cylindrical surface workpiece was performed. The effects of non-uniform deformation of elastic cushion and spring back after unloading on the precision of formed workpiece were investigated. The simulation results show that using elastic cushion can effectively suppress generation of dimples, but have an effect on precision of formed workpiece. In addition, the amount of spring back after unloading is small, and the effect of the non-uniform deformation of the elastic cushion on the precision of the MPSF workpiece is larger than that of the spring back. A method based on the iterative corrections according to the numerical simulation results was proposed to compensate the non-uniform deformation of elastic cushion and the spring back to enhance the accuracy of MPSF.