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)

The article is concerned with blank development when deep drawing nona xisymmetric, prismatic cups with a flat bottomed punch. Two processes are considered, one of which is the calculation of optimum blank shape s when deep drawing square cups; here ''optimum'' means that the cups have essentially a flat top after the drawing process. The second proc ess is to design a blank such that the finished component is a partial ly drawn cylindrical cup possessing a square flange of some specified dimensions. An inverse finite-element technique was developed to perfo rm the analysis for calculating the blank shapes. In addition to blank shapes, it was possible to predict the limiting drawing ratios, the m aximum draw depth and the drawing load. Although the entire drawing pr ocess is not modeled, it is possible to assess the influence of certai n processing parameters such as blank shape, the coefficient of fricti on, blank holder force, and die radius on the drawing force and limiti ng 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 reason able.