Generate Tooling Mesh by FEM Virtual Forming Model for Springback Compensation in Die Surface Design of Sheet Metal Stamping

An iterative FEM algorithm has been recently developed to compensate for springback in die surface design of sheet metal stamping. In each iteration of this algorithm, a new set of tooling mesh needs to be generated based on the part geometry after the so called “spring-forward” deformation. This geometry is represented by finite element mesh of the blank. Without CAD files, regular mesh generators can not handle the task. This paper presents a technique to generate such tooling mesh by means of a finite element calculation. After the spring-forward simulation, a virtual forming model is constructed. The virtual die and virtual punch are made from the part mesh with material changed from deformable to rigid. The virtual workpiece is generated by copying the die mesh and changing rigid material to deformable. The virtual workpiece is placed in between the virtual punch and the virtual die and then a FEM calculation is conducted to press the virtual workpiece into the shape of the virtual die. The needed new tooling mesh can then be easily obtained from the deformed virtual workpiece. The new tooling mesh generated by this technique has the same configuration as the original tooling mesh and preserves geometric features of the part design, so that the CAD engineers who receive the modified die surface geometry in the form of FEM mesh can work on the files with ease.