Study On Grease Elastohydrodynamic Lubrication Of Line Gear Pair

Line gear(LG)is a new type of gear transmission mechanism,which is mainly suitable for medium/light load and small size occasions.In recent years,LG has made great progress in geometric design theory.A series of achievements have been made in the manufacturing technology,and preliminary progress has also been made in industrial applications.However,as a kind of mechanical transmission part,the tribological design theory of the LG has not been completed,which restricts its popularization in the industrial application.So far,the tribology of the LG has only completed the oil elastohydrodynamic lubrication(EHL)design theory of arbitrary intersecting LG,other aspects need to be further studied.Lubrication has an important influence on gears,and good lubrication state can ensure the long-term efficient and stable transmission of the gears.Lubricants can’t provide enough film thickness for gears when they operated at slow speeds,which seriously affect the life of the gears.As a result,more and more people start to use grease.The LG is suitable for the tiny mechanical transmission,and its tooth surface speed is small.Therefore,the study of grease elastohydrodynamic lubrication of the LG has important guiding significance for its industrial application.In this paper,the design theory of grease EHL for LG pair is studied and established.The main contents are as follows:1.Establishment of mathematical models of the teeth surfaces of LG.Based on the existing contact curve equation of LG,a general mathematical modeling method of LG teeth surfaces was presented by applying the knowledge of differential geometry and the theory of spatial geometry modeling.The meshing models of parallel axis,arbitrary intersecting axis and vertical skewed axis LG were established in Mathematica software.The kinematic simulation of the meshing process of the parallel axis LG has been carried out,and that proved the correctness of the mathematical modeling method of LG teeth surfaces.2.Establishment and optimization of the contact equivalent models of the parallel axis and vertical skewed axis LG pair.On the basis of the mathematical models of teeth surfaces LG,the contact equivalent models of LG pair with parallel axis and vertical skewed axis were established by applying contact mechanics knowledge and EHL theory.The influences of the parameters of the LG on the ellipticity of the contact area were discussed,and the criteria for optimizing the parameters of the LG were given.The design method of line tooth based on elastohydrodynamic lubrication was obtained.3.Analysis of the grease EHL state of the LG pair.The experiments of point contact grease EHL were carried out,and the central film thickness and the minimum film thickness of these experiments were obtained by using optical interferometry.The calculation results of a numerical calculation program for elliptical contact grease EHL were given and compared to the results of corresponding experiments,the comparison results proved the rationality of the numerical calculation program.The program was applied to calculate the result of the grease EHL state of the contact equivalent model of LG pair and its results could provide the theoretical guidance for the selection of the LG’s application conditions.4.Development of a LG drive test rig.According to the characteristics of the LG transmission,the test rig of the LG transmission is designed and developed.This test rig can provide test conditions for the test of comprehensive transmission performance of each series of LG.