Abstract: With the preform die shape as the research object, the optimization design of metal forging is studied. The deformation uniformity and deforming force of the final forging are considered in the multiple objective function. The optimization objective is to optimize the deformation uniformity and the deforming force of the final forging at the same time so the best quality of the final forging can be obtained. Based on FEM, the multiple objective preform optimization design is carried out by using the sensitivity analysis method. The expression forms of the total objective function and the sub-objective function are given. The sensitivity equations of the total objective function and the sub-objective functions with respect to the design variables are developed. On this basis, a FORTRAN software used to perform the multiple objective perform design is developed. And then, the preform die shape of an H-shaped forging process is designed. The total objective function, sub-objective function, the perform die shape and the effective strain, y-stress distribution of the forging during the optimization are given. The results show that after optimization the total objective function, the deformation uniformity sub-objective function and the deforming force sub-objective function decrease 13%, 33% and 6% respectively. The goal that the deformation uniformity and the deforming force are optimized at the same time is achieved.

Key words: Deforming force, Forging, Multiple objective, Preform, Sensitivity, Uniformity