Research on gear forging in China

China’s gear manufacturing industry started relatively late. It began to produce gears in the s of the last century and formed its own gear manufacturing system in the s. Although it started late and there is a certain gap between technology and 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.

Kou Shuqing and Yang Shenhua 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 displacement theory. Cheng Yu, Chen Deli and Yang Cheng studied the hole shunting, die structure with insert and mandrel by using the floating die closed die forging method and shunting principle, and obtained the best hole diameter, insert height and mandrel diameter.

Zheng Jianshe, Fu Weiping and Huo Jiwu put forward a set of new optimization design scheme and processing and manufacturing method for the process equipment in the process control of spur bevel gear processing. Zheng Jianshe and Li Jinhai 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 spiral bevel gear of automobile drive axle after precision die forging and near net shape, This method can not only improve the processing efficiency and material utilization of spiral bevel gear, but also improve the transmission performance of gear.

Aiming at the problems existing in the open die forging process of spiral bevel gear, Tian Fuxiang, Wang Zejing and Yin Deliang put forward a new process and new die structure of spiral bevel gear without flash, which significantly reduces the forging deformation force, material consumption and production cost, and improves the service life and production efficiency of the die. Hu Chengliang, Liu Quankun and Liu Yongxi 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, a new rigid translational final forging process of spur gear is proposed.

Chen Xuewen, Wang Jin and Chen Jun proposed a forging process optimization method based on the reduced 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 damage accumulation theory, which can be used for life prediction and reliability analysis of dies.

Wang Huajun, Xia Juchen and Qian Yingping studied the closed die forging of spiral bevel gear by using the method of physical simulation, revealed the flow law of metal 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 workpiece handle instead of large end punch. Nie Aiqin and Wang gangchao applied the cold precision forging technology of cylindrical spur gears to production practice, put forward the tooth cavity shunting process, designed 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 tooth edge line, Moreover, the load drop is small, which can not completely avoid the sharp rise of the load in the final stage of filling. Tan Xianfeng, Liu Xia and Hu Defeng analyzed the influence of the size of blank aperture on the forming process of spur gear under the two schemes of small mandrel constrained shunting and flange shunting based on the principle of constrained shunting, and obtained the best process scheme to improve the filling performance and reduce the working load.

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