In view of the problems of large material waste and high cost caused by the traditional die design and process formulation based on experience and experiment in the hot forging of the driven spiral bevel gear blank of ZHY gear, a numerical simulation method is proposed to study the forging process. Aiming at the problem that the single step method can not reflect the influence of the residual stress of the previous process on the next process, a multi-step method for numerical simulation of forging process is proposed, that is, multi-step analysis of upsetting process and die forging process. The following work is mainly completed:

1. The multi-step analysis of the upsetting process and die forging process of the driven wheel is carried out, and the metal flow law of the upsetting process and die forging process is obtained, and the equivalent stress-strain and temperature distribution of the forgings during the final forging are obtained. The curves of equivalent stress, strain and temperature at three points with time were obtained. The stroke load curve of the total forging process is obtained, that is, the forming load at different strokes of the forging process. The results show that the large stress, strain and high temperature during the final forging of the driven spiral bevel gear blank occur at the steps of the outer side and the flash and the steps of the inner side and the concave thin layer of the driven spiral bevel gear blank, indicating that the metal flow is difficult at these two steps. The numerical simulation results were compared with the real forgings to verify the correctness of the numerical simulation.
2. According to the numerical simulation results, the die structure of die forging process was improved. The stress, strain, temperature distribution and forming load of driven spiral bevel gear blank during final forging before and after die improvement were compared, and the influence of die structure on forming effect was analyzed.
3. Research the influence of different initial forging temperature and different friction on the forming effect.
4. Research the relationship between forging energy consumption and initial forging temperature.