Numerical simulation and experimental study on cold extrusion process for clutch outer gear hub with inner tooth shapes

In this study, the clutch outer gear hub with inner tooth shapes was formed in five steps associated with three processes to pre-form the cup-shaped blank and two extrusion processes to perform the inner tooth shapes. The extrusion processes were the focus of this investigation because the dimensional accuracy of the inner tooth was the primary consideration to control the automobile transmission functionality. The cold extrusion process of the clutch outer gear hub was simulated by the finite element software DEFORM-3D, and the influences of process parameters such as the entrance angle of extruding punch, the thickness of initial blank, and the length of calibration band on forming load, tooth filling, and stress distribution were investigated. The simulation results show that the rounded corner of inner tooth in the clutch outer gear hub is fully filled, the effective stress and the forming load are relatively small with the entrance angle of extruding punch of 30°, the thickness of initial blank of 6.0 mm, and the length of calibration band of 10 mm. Finally, the experiments were carried out by the cold extrusion forming of the clutch outer gear hub. The results prove the feasibility of the cold extrusion process and the correctness of the numerical simulation results.