Bevel gear is a very important mechanical part in industry. Its main characteristics are that it can withstand large loads, work stably, and has low noise and vibration. It is widely used in the automobile main reducer, and plays a vital role in the transmission of power and movement process [1]. The failure of bevel gear is mainly related to working conditions, including stress, load, temperature and environment. The main factors of bevel gear failure include design, materials, processing, installation, environment and use.
The fracture analysis of bevel gears is an important technical means to judge the fracture form and fracture mechanism of bevel gears. The fracture morphology can truly record the cause, propagation and fracture process of cracks. Therefore, it is not only the basis for studying the micro mechanism of fracture process, but also the reliable basis for analyzing the fracture cause. Because the residual stress on the surface of bevel gears has an important influence on the fatigue life of bevel gears, the detection and analysis of residual stress has become a new means of failure analysis and detection.
1) After carburizing, quenching and tempering, because of the existence of internal oxidation soft layer, the bevel gear is easy to produce stress concentration during shot peening, which becomes the starting point of fatigue crack source. It is suggested to select low Si materials on the premise of ensuring the hardenability of the materials, try to control the content of Cr, Mn, Ti, V and other alloy elements, purify the carburizing feed gas (methanol or natural gas), reduce the content of oxidizing components, such as water, sulfur and other impurities, and reduce the internal oxidation degree of the products after heat treatment.
2) Strengthening shot peening can improve the bending fatigue strength and contact fatigue strength of bevel gears. It is an important way to improve the anti seizure ability and increase the service life of bevel gears.
3) Control the purity and segregation of inclusions from the source of materials, cooperate with the pressure quenching process to reduce the deformation of heat treatment, improve the consistency of the contact zone, and improve the working conditions.