Spur Gear Friction Characteristics Analysis Under EHL

Gear is one of the important parts are widely used in mechanical engineering; gear drive is relatively the most useful way of mechanical transmission. However, in the process of gear transmission, because of the gear meshing of collision and impact, resulting in gear mechanism producing vibration and noise; Further, the gear meshing process is repeatedly subjected to the effect of changing load and contact stress, which leads to the wheel teeth are prone to tooth root bending fatigue fracture and tooth surface pitting, such cases will be to some extent affect the transmission efficiency, transmission accuracy and service life of the gear, therefore, the study of tooth strength is essential.The contact fatigue strength design theory of involute spur gear transmission is based on Hertz contact theory, and Hertz contact theory is built on the ideal contact state that the smooth surface without lubrication and friction, it has to do with the actual working condition of the gear transmission gap is larger. Gear actual working conditions due to many factors, such as tooth surface roughness, temperature and shock load, have made the drive gear in the elastichydrodynamic lubrication conditions. There is still friction although most of the gear is in the lubrication conditions. The friction between the meshing wheel will causes the change of temperature and contact pressure, reduce gear transmission efficiency and shorten its service life. Thus, the effect of friction cannot be ignored.The research object of this paper is involute spur gear, through finite element analysis methods combination of gear EHL numerical analysis to study gear transmission. Firstly, this paper established the mathematical model of gear EHL, solving the oil film pressure, film thickness and friction coefficient by numerical calculation method. Finally, finite element analysis on the spur gears is based on the results of numerical calculation. This article mainly did the following work:(1) This paper combined the study of many scholars and the actual working condition and structure of involute spur gears. Establish the mathematical equations of oil film thickness, oil film pressure and friction coefficient under the condition of involute spur gear lubrication. (2) Compiled the program based on the theory of spur gear EHL the calculation, and got the numerical calculation result of film thickness, oil film pressure and coefficient friction, and then collate and analyze the calculation results.(3) Based on finite element analysis software ANSYS platform, the oil film pressure and Hertz pressure as a load, and analyzed the stress of gear.