A new blank design method is suggested as an effective tool based on the ideal forming and FE-analysis method in the sheet metal forming process. The method consists of two stages ; initial blank design stage and optimum blank design stage.
In the initial blank design, it deals with only one step from the final shape to the initial blank using the ideal forming theory. Based on this theory, a three-dimensional membrane finite element code has been developed for ideal sheet forming. The design of the initial blank for forming a cylindrical cup, a rectangular cup, and a front fender are presented as examples.
In the optimum blank design stage, it computes an optimum blank of the target shape using the initial blank calculated from the initial blank design. The target shape is compared with the shape deformed from the initial blank using the FEM analysis code, then the shape errors are defined. A deformation path iteration method is introduced to minimize the shape errors iteratively. In this method, volume addition and subtraction are tried iteratively along the deformation path until the error is reduced within the error bound. As examples of the initial blank design stages, cylindrical and rectangular cup are employed
From the computed optimal blank, the formability of the blank is studied on the forming limit diagram. From the results, it is shown that the optimum blank is deformed more smoothly than the unoptimized plain square blank with improved formability.
Until now, the results illustrates the information that the optimum blank design tool is very useful tool in the design state. Through the investigation, the proposed systematic method of optimal blank design is found to be effective in the design of the deep drawing process.
