Abstract: A new sensitivity analysis method for perform die shape design in metal forging by controlling the deformation uniformity is developed. The optimization problem is to minimize the square summation of the difference between effective strain of arbitrary element and the average effective strain over all elements so that more uniform deformation within forging can be obtained. The perform die shapes are presented by cubic B-spline curves. The control points of B-spline curves are used as the design variables. The form of the objective function is given. The sensitivity equations of the objective function, elemental effective strain rate and the components of elemental strain rate with respect to the design variables are developed. The procedure of the optimization in this method is given. Using this method, the perform die shape of a cylinder upsetting process is designed. In order to check the optimization result, a deformation uniform factor is introduced. Comparison of the factor obtained by optimization and non-optimization shows that the optimized result is satisfactory.

Key words: Analysis, Deformation, Design, Forging, Preform, Sensitivity, Uniformity