New Cold Forging Process of Retaining Pin Using FEM Based Simulation

Abstract

Retaining pins are generally used as the parts of automobile gears, axes, crankshafts, and seat belts, which are proceeded three-stage forming and then drilling processing in the original manufacturing procedure. However, the fixture seizing in the drilling processing could result in rod surface damage and dent, and the depth tolerance exceeding the drawing specifications after the drilling causes the major defects in product manufacturing. This study attempts to modify the cold forging process by adding one stage and replacing the original mechanical drilling processing with backward extrusion and forging engineering. In the research process, Finite Element Method is utilized for analyzing and simulating the forming load at each stage. The analysis results show that increasing the original 3-stage forging process to 4-stage could assist in solving the problems of rod dent and depth tolerance exceeding the drawing specifications after the drilling. Although the die cost would increase with an increasing stage, the new process allows the forging force being more even and the die life being prolonged, in consideration of the overall production costs.