Adhesive Wear Calculation For Modified Gear Under Mixed Lubrication

Gear transmission is more and more widely used in new energy vehicle gearbox,robot precision reducer,aerospace transmission system and other fields.When gear operates under heavy load or bad lubrication,lubrication film is easy to break.Consequently,two meshing tooth surfaces directly contact each other,resulting in the wear and even failure of the tooth surface.In order to improve the lubrication state of gear and reduce tooth surface wear,involute spur gear is regarded as research object.The mixed elastohydrodynamic lubrication(EHL)models in line and point contact are established separately.Adhesive wear depths of standard and modified gears under mixed EHL are calculated separately.Furthermore,effects of gear macro,micro parameters and working conditions parameters on lubrication characteristics,friction and wear characteristics are investigated.The main contents are presented:(1)Based on Hertz contact theory and ZMC elastic-plastic contact model,the actual contact load,pressure and area of rough surface with contour height subject to Gauss distribution are derived.The results indicate that the increasing actual contact load and pressure of asperity will increase actual contact area of asperity and reduce the average distance of the rough surface.(2)Based on the one-dimensional mean Reynolds equation and ZMC elasticplastic contact model,a steady-state line contact mixed EHL model is established.The progressive mesh densification method is used to solve the problem.The calculation results are compared with the simulation results in existing literature to evaluate reliability of presented model.The effects of load,speed and material parameters on lubrication characteristics are analyzed.The results indicate that reducing load,material parameters and increasing speed parameters can improve the lubrication state.(3)Considering time-varying effect,the transient line contact mixed EHL is applied to spur gears.Based on the modified Archard adhesive wear model,the adhesive wear model of standard spur gear under mixed EHL is established.The calculated wear rate is compared with the simulation results and experimental data in existing literature to verify effectiveness of presented model.The adhesive wear depth of standard spur gear under mixed EHL is calculated,and the effects of modulus,pressure angle,input power,input speed and surface roughness on tooth surface lubrication,friction and wear characteristics are analyzed.The results show that increasing modulus,pressure angle,input speed and decreasing input power and surface roughness can improve the tooth surface lubrication state and reduce the adhesive wear of tooth surface.(4)Based on the two-dimensional mean Reynolds equation and ZMC elasticplastic contact model,a transient point contact mixed EHL model is established,and the calculation results are compared with the simulation results in existing literature to verify accuracy of presented model.Combined with the modified Archard adhesive wear model,the adhesive wear depth of crowed modified spur gear under mixed EHL is calculated,and the effects of modulus,pressure angle,input power,input speed,surface roughness and crowed modification on tooth surface lubrication characteristics,friction and wear characteristics are investigated.The results show that reducing the amount of crowed modification can improve the tooth surface lubrication state and reduce the adhesive wear of tooth surface.The influence law of other parameters is consistent with the adhesive wear model of line contact mixed EHL.