China’s gear manufacturing industry started late. It began to produce gears in the 1950s and formed its own gear manufacturing system in the 1960s. Although it started late and there is a certain gap between the technology and that of western developed countries, many experts and scholars in China have studied the forging process of gears. Similarly, the research mainly focuses on the precision forging of gears.
Koushuqing, yangshenhua, etc. studied the cold precision forging method of spur gear, and put forward the process scheme of closed upsetting and extrusion hole split two-step forming and the tooth profile die correction method based on the displacement theory. Chengyu, chendeli, Yang Cheng, etc. studied the die structure of hole shunting, with insert and with mandrel by using the closed die forging method of floating die and the shunting principle, and obtained the optimal hole diameter, insert height and mandrel diameter. Zhengjianshe, fuweiping, huojiwu, etc. put forward a new set of optimization design scheme and manufacturing method for the technological equipment in the process control of spur bevel gear machining.
Zhengjianshe and lijinhai studied the new forming technology of spiral bevel gear tooth surface and the design method of closed hot forging die, and put forward a set of new process procedures and processing methods for the machining of automotive drive axle spiral bevel gear after precision die forging near net shape, This method can not only improve the machining efficiency and material utilization of spiral bevel gears, but also improve the transmission performance of gears. Tianfuxiang, wangzhejing, yindeliang, etc. put forward a new process and a new die structure for the open die forging of spiral bevel gear without flash, which significantly reduced the forging deformation force, material consumption and production cost, and improved the service life and production efficiency of the die. Huchengliang, liuquankun, liuyongxi, etc. studied the metal flow law in the forging process of spur gears, and put forward the assumptions of radial rigid translational flow mode and axial uniform flow mode, so as to reduce friction resistance and improve uneven deformation, Based on the rigid translational flow model, a new rigid translational final forging process for spur gears is proposed.
Chen Xuewen, Wang Jin, Chen Jun, etc. put forward a forging forming process optimization method based on the reduced descending gradient method. The maximum damage value of all elements of the forging is used as the index to measure the deformation damage of the forging, and the initial height diameter ratio of the part blank is used as the design variable to establish the mathematical model of the optimization design, The optimization of non isothermal hot forging process has achieved good results. Lou Luliang and Li Fuguo studied the random fatigue damage of forging dies. They established a random fatigue damage analysis model of forging dies based on the damage accumulation theory, which can be used for life prediction and reliability analysis of dies.
Wanghuajun, Xia Juchen, Qian Yingping, etc. studied the closed die forging of spiral bevel gear by using the method of physical simulation, revealed the metal flow law in the closed die forging, and proposed the design of closed die forging die with double action punches at large and small ends by using local heating and replacing the large end punch with the workpiece handle. Nieaiqin, wanggangchao, etc. applied the cold precision forging technology of cylindrical spur gears to the production practice, put forward the tooth cavity shunting process, designed the special die tooling, and studied the two shunting processes of tooth top shunting and upper tooth end shunting. The results show that the upper tooth end shunting process can not effectively improve the filling performance of the tooth edge line, Moreover, the load drop is not large, which can not completely avoid the sharp rise of load in the final stage of filling. Tanxianfeng, Liuxia, hudefeng, etc. analyzed the influence of the blank hole diameter on the forming process of spur gears under the two schemes of small mandrel constrained splitting and flange splitting based on the constrained splitting principle, and obtained the best process scheme to improve the filling performance and reduce the working load.