Determination of the Optimum Blank Shape When Deep Drawing Nonaxisymmetric Cups, Using a Finite-Element Method : Simplified Determination of Optimum Blank Shape and Limiting Drawing Ratio by Inverse Finite-Element Procedure

Abstract

The article is concerned with blank development when deep drawing nonaxisymmetric, prismatic cups with a flat bottomed punch. Two processes are considered, one of which is the calculation of optimum blank shapes when deep drawing square cups ; here "optimum" means that the cups have essentially a flat top after the drawing process. The second process is to design a blank such that the finished component is a partially drawn cylindrical cup possessing a square flange of some specified dimensions. An inverse finite-element technique was developed to perform the analysis for calculating the blank shapes. In addition to blank shapes, it was possible to predict the limiting drawing ratios, the maximum draw depth and the drawing load. Although the entire drawing process is not modeled, it is possible to assess the influence of certain processing parameters such as blank shape, the coefficient of friction, blank holder force, and die radius on the drawing force and limiting drawing ratio. Some of the theoretical predictions for the limiting blank size in deep drawing square cups from optimum-shaped blanks are compared with published data, and the agreement is found to be reasonable.