Research On The Frictional Property Of Interface Of Rough Tooth Surfaces And The Dynamics Of Gear System

With the development of society and the improvement of manufacturing level,the requirements of reliability and environmental protection of gear transmission system are higher.Therefore,the contact characteristics and dynamic characteristics of gear transmission have become a hot issue among researchers in recent years.In the gear meshing process,the tooth surface is always in the mixed lubrication or boundary lubrication state.In these lubrication states,the tooth surface topography will play an important role in the meshing process.The research of the effect of tooth surface topography on the friction and dynamic characteristics during the gear meshing will provide reference for the optimization design of gear tooth surface and the gear modification method,which has important theoretical value and application prospect.In this dissertation,the frictional noise,elastic deformation and friction coefficient variation of the sliding-rolling line contact interfaces with different topographies under elastohydrodynamic lubrication(EHL)condition are investigated based on the theory and experiment.By this way,the relationship between the 3D surface topography parameters and surface friction characteristics is explored.The time-varying friction coefficient curves of tooth surface are established,and then they are introduced into the six degrees of freedom gear dynamic model.The dynamic responses of gears with different tooth surface topographies under various typical operating conditions are calculated by using this model,and the relationship between the tooth surface topography and the dynamic characteristics of gear system is investigated.The main research work and achievements of this dissertation are as follows:(1)The 3D surface topography parameter system of ISO 25178 and the calculation method of these parameters are introduced.The textured surfaces with different topographies are designed and fabricated by laser processing,and the 3D surface topographies of these surfaces are measured and characterized based on ISO 25178.(2)The finite element model of line contact frictional state is established.The explicit dynamic method is used to simulate the process of line contact friction under different operating conditions.The frictional noise and the frictional energy are calculated by this method,and the relationship between the 3D surface topography parameters and the line contact frictional noise is studied.The line contact frictional noise of surfaces with different topographies under EHL condition is measured by using the two disk tribo-tester.Based on the test results,the generation law and influencing factors of line contact frictional noise are analyzed,and the mechanism of surface topography affecting frictional noise is explored.(3)In combination with the elastohydrodynamic lubrication theory and the Amplitude Reduction method which based on the spectrum analysis of surface topography,the elastic deformation analysis method of line contact surface topography under EHL condition is studied.The elastic deformations of surface topography under different operating conditions are calculated by using this method.The influences of surface topography elastic deformation on the topography characteristics and lubrication characteristics of the contact surface are investigated by analyzing the 3D surface topography parameters and the film thickness ratios before and after the elastic deformation.(4)The variation of friction coefficients with the operating condition parameters under line contact condition is studied based on the two disk friction test,and the results are analyzed by 3D surface topography characterization.Combining the calculation results of meshing parameters in the gear meshing process and the test results,the time-varying friction coefficient curves of gears with different tooth surface topographies are obtained.By this way,the effects of operating conditions and tooth surface topography on the time-varying friction characteristics of gears are studied comprehensively.(5)Considering the effect of time-varying mesh stiffness and time-varying friction coefficient,a six degrees of freedom tribo-dynamic model for gear system is established.The dynamic responses of the gear systems with different tooth surface topographies are calculated by using this model.According to the analysis of calculation results,the influences of the tooth surface topography on the dynamic characteristics of the gears during meshing are studied,and the change law of this influence is also discussed.This research will provide a new method for the study of gear dynamics considering the 3D topography features of tooth surface.