Gear is an important part for transmitting power in mechanical devices. The Japanese mechanical society has conducted systematic investigation and Research on gear transmission failure cases in various industries. About 74% of gear transmission pair failures are caused by gear surface fatigue failure, which fully shows that the strength and service life of gears are closely related to the advantages and disadvantages of mechanical devices. In recent years, with the progress and development of modern vehicles, new energy vehicles, military vehicles, ships, aerospace vehicles, high-speed railway facilities and other technologies, the power transmission mechanism further requires the gear to have the characteristics of high strength, high speed, high efficiency, high life, lightweight and miniaturization (four high and one light and small). This not only puts forward new topics for the design of gears, but also brings new R & D tasks for the development of new materials and innovative material processing technology. Among them, surface strengthening technology is the key to ensure the realization of four high and one light and small gears.
At present, there is still a considerable gap between China and Europe, the United States, Japan and other countries in the design and manufacturing technology of high-strength gears, especially in the strength and service life of parts and components of high-end automotive and mechanical products and foreign products, which restricts the development of automotive automatic transmission and other high-end electromechanical equipment in China, Therefore, it is imperative to comprehensively improve the high strength of high-end gears.
(1) Surface strengthening technology is one of the important technologies of high-strength automotive gears, which occupies an important position in the field of automotive technology. At present, it can not fully meet the target requirements of automotive automatic transmission in lightweight, high speed, high torque and high durability. More attention should be paid to the basic and Application Research of gear material and surface strengthening.
(2) Surface strengthening technologies such as automobile gear surface heat treatment, shot peening and surface coating have a good practical effect on improving the fatigue strength limit of automobile transmission gears. While introducing and absorbing international technology, further studying the gear surface integrity and anti fatigue strengthening mechanism is one of the important tasks to solve the current technical problems of high-strength gears in China.
(3) The numerical simulation of automotive gear surface strengthening should be combined with the interdisciplinary disciplines of thermodynamics, phase transformation thermodynamics, material mechanics, solid mechanics, tribology and gear dynamics. Establishing the quantitative relationship between gear surface strengthening parameters and the improvement of gear performance will be the focus of research in this field. For the composite surface strengthening technology of gears with high resistance to contact fatigue and high resistance to bending fatigue, we should pay attention to the interaction mechanism and basic research of various surface strengthening treatments, and explore a new composite surface strengthening method of automobile gears from the perspective of multi factor comprehensive indicators, so as to achieve the goal and requirements of high strength in the development of automobile gears.
As we all know, according to the research practice, to improve the fatigue strength and life limit of automobile gears, it is necessary to improve and optimize the alloy composition of materials, carburizing and carbonitriding heat treatment technology, and must also be combined with the research and development of surface strengthening treatment technology of automobile gears, that is, to achieve comprehensive gear surface integrity and better gear fatigue resistance, so as to realize the contact fatigue limit of high-strength automobile gears High performance requirements for bending fatigue limit, fatigue endurance life and optimal friction coefficient.
In recent years, in order to develop new markets, automobile companies are constantly improving the guaranteed driving mileage. Many internationally famous automobile companies have increased the guaranteed driving mileage to more than 340000 kilometers. In order to achieve this performance index, automobile companies in the United States, Japan and Europe have put forward stricter market specification requirements, strengthened the research on improving the fatigue strength and life of automobile gears, and carried out in-depth research and development from the perspective of comprehensive indicators of various factors. This mainly includes the analysis and optimization of gear alloy materials, the optimal heat treatment technology of automobile gears, and the research of automobile gear surface strengthening technology, such as chemical treatment of manganese phosphate conversion coating, compound shot peening on tooth surface, molybdenum disulfide plus particle shot peening on tooth surface, and has achieved good practical results in the application of automobile automatic and manual transmission.