Rigid–plastic finite element simulation for process design of impeller hub forming

A torque converter impeller hub is usually made through sequential cold forming processes: forward extrusion, upsetting, piercing and finishing. The finishing process is a closed-die forging where the load increases abruptly due to flash formation and the defect of the under filling in the finished product is happened occasionally. In this study, rigid–plastic finite element simulation was applied to analyze the deformation characteristic of the whole impeller hub forming processes and to optimize the process. As a result, two kinds of improvement for the impeller hub forming process satisfying the limit of the machine’s load capacity and the geometrical quality are suggested and the results are verified by experiment.