On the determination of the blank shape contour for thin precision parts obtained by stamping

The present study deals with the "automatic" determination of the initial blank shape contour for 3D thin metallic precision parts obtained by stamping, knowing the 3D CAD geometry of the final part (the desired product). The forming process can involve several steps presented in this paper that consists in applying a heuristic method of optimization to find out the initial blank shape of thin precision metallic part in order to obtain a final part, with a required 3D geometry (specified). The purpose of the present approach is to replace the experimental trial and error optimization method used currently, which is expensive and time consuming. The principle of the "heuristic" optimization method is to first estimate the blank shape using the Inverse Approach, then to compensate the shape error calculated in each node of the blank contour. The "heuristic" optimization loop is done using a precise incremental code (Abaqus Explicit or Stampack) and, the iterations loop is stopped when the shape errors are within some initially fixed tolerances. The method is tested in the case of a special stamping process where the parts are pressed in one or more steps using a manual press, without blank holder and by the mean of tools having complex shape. The sensitivities of the process parameters regarding the optimal solution are investigated.