| Due to the advantages of high transmission accuracy,high load-bearing capacity,reliable operation and long service life,gears are widely used in automotive,railroad,aviation and heavy industry.In the modern industrial field,high speed and heavy load are common working conditions of gear transmission,so the demand for high performance gears is increasing.Excessive dynamic load can easily cause lubrication failure leading to tooth wear,which seriously affects the performance and service life of gears.Therefore,it is important to study the characteristics of gear elastofluid lubrication to optimize the performance of gear transmission system.In spiral bevel gear elastofluid lubrication,the existing research does not systematically study the relationship between the speed and load,roll suction angle and surface roughness and the lubrication characteristics of spiral bevel gears,and does not closely correlate the spiral bevel gear tooth surface modification and theoretical meshing state with its elastofluid lubrication characteristics,so it cannot well guide the tooth shape design of spiral bevel gears to optimize the lubrication performance of spiral bevel gears.To address the above problems,this paper adopts differential geometry theory,elastofluid lubrication theory and multiple mesh method to study the calculation method of elastofluid lubrication of spiral bevel gears,and develops the elastofluid lubrication program for spiral bevel gears.The elastofluid lubrication characteristics of tooth contact are analyzed,and the influence of working conditions and tooth meshing state on the elastofluid lubrication characteristics is obtained,and a preliminary technical procedure for optimizing the elastofluid lubrication performance of spiral bevel gears by tooth shape design is established.The main research work of the thesis is as follows.The tooth equations of the spiral bevel gear were derived,the spiral bevel gear tooth contact model was established,and the tooth geometry parameters and motion parameters were calculated.The contact ellipse under loading condition is solved by Simpson’s integral method with variable steps.The geometric characteristics required for the analysis of the elastofluid lubrication of the spiral bevel gear were obtained.Based on Reynolds equation,oil film thickness equation,load balance equation,viscous pressure equation,and dense pressure equation,the computational model of elastofluid lubrication for isothermal elliptical contact of spiral bevel gears is derived,and is dimensionless as well as discretized,and the numerical calculation of load balance with relative error is taken as the criterion.Based on the idea of finite difference method,the entire solution domain is divided into twodimensional equidistant meshes,and the elastic deformation coefficients of the entire solution domain are calculated using the multiple mesh integration method.The pressure distribution and film thickness distribution are solved by the multiple grid method,and an elastic flow lubrication program for spiral bevel gears is written in the language of the spiral bevel gears,and the feasibility and accuracy of the program are verified by example analysis.The effect of working conditions on the elastofluid lubrication characteristics was analyzed,and the correlation between the load and speed,the size of the roll suction angle,and the surface roughness on the elastofluid lubrication characteristics was obtained.The influence of tooth meshing condition on the elastofluid lubrication characteristics is also analyzed,and the correlation between transmission error,contact trace tilt angle and contact trace length and elastofluid lubrication characteristics is obtained.Finally,the correctness of the relevant conclusions is verified by examples.The thesis research has completed the establishment of the calculation model of spiral bevel gear elastofluid lubrication,developed the calculation program of spiral bevel gear elastofluid lubrication,and put forward the guidance suggestions for the optimization of lubrication performance of spiral bevel gears based on the analysis of the influence of working conditions and tooth meshing state on the elastofluid lubrication characteristics of gear pairs.The research results of the paper have good engineering application value for guiding the optimized design of spiral bevel gear tooth shape based on lubrication performance. |
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