Application of new forming technology in China gear production

Although the traditional gear manufacturing process has been constantly improved, but it always has some inherent disadvantages. Many scholars completely get rid of the constraints of the inherent traditional forming process, and put forward some new gear forming processes to improve product quality, dimensional accuracy, material and energy utilization.

In the traditional technology, the cup-shaped thin-walled internal gear is produced by the combination of cutting and welding technology. Sun Lingyan introduced the application of spinning forming technology in this kind of gear production in his doctoral dissertation. It effectively made up for the shortcomings of traditional complex technology and poor product quality stability. It is a technological innovation in the field of gear processing. The research work mainly focuses on the spinning deformation mechanism of cup-shaped thin-walled internal gear, the restriction relationship between process parameters, forming process and optimization of process parameters. A three-dimensional elastic-plastic numerical simulation model of internal gear spinning is established, which can take into account the calculation accuracy and efficiency. The results of simulation and test show that the difference of tooth thickness to tooth height ratio of internal gear (at the tooth root) will lead to the change of material flow during the forming process. According to the size of tooth thickness to tooth height ratio of parts, the spinning forming internal gear is divided into involute internal gear and straight internal gear, and the technological scheme is put forward. The process test shows that the optimization scheme is feasible.

Spur gear is a basic mechanical part with a large quantity and a wide range. At present, the main production methods in China have low production efficiency and serious material waste. Sun Hongxing et al. Studied the forming process of spur gear by the method of numerical simulation and experiment, analyzed the filling and load under different forming processes, studied the influence of friction factors on the forming process, and thought that keeping the uniformity of filling is the key to forming success. On this basis, a new forming process of spur gear is put forward: one step uniform forming process of bi-directional extrusion and upsetting.

In order to solve the problems of complex die structure and relatively large rolling force existing in the cold rolling technology of hypoid gear, dangyugong and others put forward a new cold rolling scheme, which simplified the die structure and adopted local line contact continuous plastic forming. In order to prove the feasibility of this scheme, the contact line between trapezoidal die and gear tooth was studied, It is found that the contact line between the grinding wheel and the tooth surface is completely coincident in the process of gear grinding by forming method.

In recent years, China has made some gratifying improvements and breakthroughs in gear manufacturing technology. Many new process schemes have been widely put into production, and the expected improvement effect has been achieved, which has taken a solid step to promote the development and application of gear manufacturing technology in China. However, there is still a big gap compared with the developed countries in the West. China should further research and explore in the following aspects: continue to research and develop new gear steel materials; further improve heat treatment tooth surface strengthening technology to improve the bearing capacity and reliability of gears; research and develop new gear heat treatment technology, For example, Isothermal Normalizing Technology of gear forging blank, low pressure (vacuum) carburizing technology, direct carburizing technology, gear carburizing and accelerating technology, gear carburizing and pre oxidation technology, gear quenching and controlled cooling technology, etc.; strengthen the application of modern technology in gear production, For example, gear heat treatment quality online control technology, gear flexible manufacturing technology, intelligent precision gear heat treatment technology, gear integrated heat treatment manufacturing technology, etc. I believe that in the near future, China’s gear production technology will be further improved, further promoting the development of China’s basic parts manufacturing industry.

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