# Contact temperature of spur gears

Gears are widely used in mechanical transmission. Due to the existence of tooth friction, the tooth contact temperature of the gear transmission system increases when it works under the condition of high load and high speed. The higher contact temperature is the main cause of the gluing, which affects the working performance or causes the failure of the gear. The parameters of gear system also have different effects on the contact temperature of tooth surface. Therefore, the calculation and measurement of the tooth contact temperature, as well as the study of the influence of the parameters of the gear system on the tooth contact temperature, have been the focus of scholars at home and abroad.

In 1937, Blok obtained the approximate formula of instantaneous contact temperature of gear by assuming the heat source as constant and moving at a constant speed. Mao K used the finite difference method to get a more practical calculation method of tooth contact temperature. Li s et al. Studied the influence of torque, viscosity coefficient of lubricating oil and surface roughness on tooth contact temperature. Taburdagitan et al. Established a finite element model to study the change of tooth contact temperature caused by friction. Longhui et al. Established the instantaneous contact temperature model of high-speed gear transmission teeth and studied the influence of relevant factors on the instantaneous contact temperature of teeth. Chen Jun et al. Applied infrared thermography technology to the measurement of tooth contact temperature, and analyzed the influence of injection pressure and torque on tooth contact temperature. Xue Jianhua et al. Established the theoretical analysis model of thermoelastic flow, and obtained the temperature field and flash temperature of the contact point. Mao Jun et al. Analyzed the law that the surface flash temperature and contact temperature of gear change with rolling distance and rolling angle. In Fu Xuezhong, the calculation model of the flash temperature of the whole tooth surface of face gear transmission is established. Gong Xiansheng et al. Used the finite element method for transient thermal analysis, and obtained the instantaneous temperature distribution of the tooth surface during the meshing process. Gu Jiangong et al. Put forward the formula of flash temperature along the contact path and the whole tooth surface of spiral bevel gear under mixed elastohydrodynamic lubrication. Gou Xiangfeng et al. Established the numerical calculation method of the contact temperature of the tooth surface, and analyzed the coupling relationship of the parameters of the spur gear system and its influence on the dynamic characteristics of the system. At present, the research results of tooth surface contact temperature are mostly single theoretical calculation or experimental measurement, the theoretical calculation and experimental comparison are less, or the calculated theoretical results and experimental measurement results are not in good agreement.

ZHY gear takes the single degree of freedom spur gear as the research object. Based on the Blok flash temperature theory and Hertzian contact theory, four numerical calculation formulas of tooth surface contact temperature under different lubrication conditions are derived. The experimental measurement is carried out with the help of the single tooth meshing tooth surface contact temperature measurement experimental platform to verify the correctness and effectiveness of the theoretical calculation method. The influences of speed, torque, viscosity of lubricating oil and backlash on the tooth surface contact temperature are calculated. The research results can provide a basis for the calculation and experimental measurement of tooth contact temperature.