The Research Of Rolling Bearing Hydrodynamic Lubrication Mechanism In Elliptical Contact Area

Rolling bearings as key components of important equipments,its good lubrication condition will extend the service life of mechanical equipments effectively and enhance the accuracy and performance.High speed angular contact rolling bearing type of B7008 C is object of study.The lubrication condition of complex flow field in tiny contact area was studied.The research of rolling bearings lubrication condition providing fundamental basic and reference for the lubrication action of high speed rolling bearings.In this study,the lubrication condition of rolling bearings was simulated using the fluid dynamics analysis software of ANSYS CFX.Two type of fluid models of lubricant were established and the non-Newtonian fluid characteristics were given.According to different boundary conditions,fifteen different rolling speeds were set upon the two different fluid models.A series of comparatively analysis of simulation results was analyzed.Finally,experimental phenomena and simulation result was comparatively analyzed.The main content contains:Firstly,according to the formula of Hertz contact stress and oil film thickness,under the given condition of load and rolling speed,the size of contact area and oil film thickness in elliptical contact area of B7008 C bearing was calculated.Then lubricate fluid model of eighteenth of B7008 C bearing,namely one rolling element unite.Secondly,because of the oil film thickness of the center of elliptical contact area was just 1?m,and the oil film thickness of free surface was 0.3mm,so,mesh generation of fluid model is the key and difficult points of the study.In order to ensure the calculate accuracy and taking the economy of calculate into account,more optimized method was adopted in this paper:The method of partrefining influenced by interaction body and the method of smooth connection inflection was integrated applied in meshing.Thirdly,according to the calculate result of pressure distribution in the surface of rolling element,the oil film pressure of lubricate were extracted by 21 probe points in both the minor axis and major axis of elliptical contact area.The chart of these probe values has concise and clearly described the distribution and variation of oil film pressure in elliptical contact area.Then the conclusions of oil film pressure of inlet of elliptical contact area is higher and oil film pressure of elliptical contact area is negative pressure were summed up.Fourthly,setting the rolling speed boundary of inner,outer rings and rolling element as this:With in the rolling speed of inner ring as standard,the rolling speed of inner,outer ring and rolling element were rolling.Set the inner ring rolling speed from 500rad/s to 5000rad/s respectively,and analyze every 500rad/s.According to the distribution and variation of oil film pressure in elliptical contact area of different rolling speed,the following conclusions were obtained:Along with the inner ring rolling speed rising,oil film pressure of the inlet of elliptical contact area was rose correspondingly,and the shape of pressure distribution was stable.In the elliptical contact area,oil film pressure was decreased along with the inner ring rolling speed rising,and the shape of pressure distribution was stable too.Fifthly,establish the fluid model without grooves of lubricate,which ignore the characteristic of grooves.Applying the same meshing method,editing the fluid characteristic of non-Newtonian,setting the same boundary condition to the fluid model.Comparatively analysis the results of without grooves fluid model and B7008 C fluid model,the following conclusions were obtained:due to the different shape and thickness of oil film,there are both the same oil pressure regularity and different distribution of a-axis and b-axis in contact area.Finally,briefly introduced the Oil film thickness Measurement system.Comparing the experimental phenomena and the simulation result,this paper come to the conclusion:when oil drop flow through the contact area, the oil film distribution condition was identical to the mass flow distribution when continuous lubricating oil flow through the contact area.