Blank design and formability prediction of complicated progressive die stamping part using a multi-step unfolding method

A multi-step unfolding method (MSUM) is developed for blank design and formability prediction of complicated progressive die stamping part. In the method, a finite element model of the inverse approach (IA) is developed at a local area according to the stamping process, and the intermediate shape is unfolded on a reference surface at the local area. Not only the influence of the connection, blank-holder force and the friction, but also the influence of the offsetting of the strain neutral layer with different radius of curvature at local area, are considered in the model, which improves the calculation precision of the blank shape at each step. The key intermediate blank shapes and initial blank shape can be generated using the method with many times in an inverse sequence. The optimum blank shape also can be designed according to the formability of the forming part. The MSUM is illustrated to the blank design of a progressive die stamping part, and a benchmark test is compared with experimental and other numerical results.