A precision sizing method for cold extruded sun gear with internal-external tooth shapes

摘要

Due to the complex metal flow in the cold extrusion of sun gear, the teeth accuracy of formed sun gear is poor. In order to improve the accuracy of extruded sun gear, a precision sizing method was proposed in this study. Finite element simulation for predicting tooth deviations of finished sun gear was performed using DEFORM, and the influences of key process parameters such as the sizing amount of external gear, interference value of internal spline, die bearing length, and friction factor on gear deviations were examined. The simulation results reveal that the accuracy of extruded sun gear can be significantly improved with the sizing amount of external gear as 0.2 mm, spline interference value as 0.10 mm, die bearing length as 19 mm, and friction factor as 0.12. Finally, experimental investigation was carried out by the developed precision shaping method. The experimental results show that the profile accuracy of external gear after cold shaping operation is the seventh, the gear lead accuracy is the eighth, and the total M value deviation of internal spline is reduced to 0.07 mm, which proves the feasibility of precision sizing method and the correctness of numerical simulation results.