Numerical Simulation and Experiment Research on Thick Plate Multi-Point Forming Process with Elastic Cushion

Abstract

Multi-point forming (MPF) is an advanced flexible manufacturing technology for three-dimensional sheet metal forming. The substance of MPF is replacing the conventional solid dies by a set of discrete punches called ‘‘punch group’’. Because the reconfigurable discrete punches are used, part manufacturing costs are reduced and manufacturing time is shortened. However due to the discrete contacts between the workpiece and punches, the dimple defects occurred, which are inevitable and particular for MPF. For thick plate, the surface defect is the mainly dimple defect during its MPF process. In this study, elastic cushion was proposed to prevent these surface defects. The dynamic explicit finite element method was chosen to implement the simulation of MPF process. The Hill’s anisotropic yield criterion was used to describe the workpiece material behavior, and the elastic cushion was described with using the hyperelastic material model. The method to determine each punch position to construct forming surface was introduced. The MPF process with and without using elastic cushion was simulated to study the effect of the elastic cushion on preventing the surface defects. The relevant experiment was implemented, and it verified that the elastic cushion is effective method to suppress the surface defects during the thick plate MPF process. Keyword: flexible forming process (FFP), elastic cushion, surface defects, multi-point forming (MPF), thick plate, numerical simulation