The objective of this study was to investigate the grease-lubricated film-forming mechanisms in the finite line contact and to improve the grease-lubricated finite line contact’s film-forming capacity.An elastohydrod...The objective of this study was to investigate the grease-lubricated film-forming mechanisms in the finite line contact and to improve the grease-lubricated finite line contact’s film-forming capacity.An elastohydrodynamic lubrication(EHL) test rig with two interferometry microscopes,which could simultaneously monitor two different contact locations in the finite line contact,was constructed in order to study the influences of the grease thickener formulation on the film thickness and lubrication condition.By using the relative light intensity method,the thickness maps of the grease-lubricated film were calculated from the interferometer images captured by the two microscopes.The test results revealed that the grease thickener’s formulation had remarkable effects on film formation and the perturbation of film thickness.For the lithium-based grease,the film’s thickness near the two ends of the roller was prone to severe perturbation caused by the conglomeration of clumps that were hard to shear.For the aluminum-complex-based grease,the fibers tended to accumulate in the middle of the roller rather than at the two ends.The urea-based grease could be easily sheared into smaller particles.In addition to the straight-line profile rollers,the logarithmic profile rollers were tested and found to effectively enhance the axial grease flow,increase the axial shear stress,and thus shear more fibers into particles within the contact area.展开更多
An account of numerical solutions to the isothermal and flooded elastohydrodynamic lubrication(EHL)of a logarithmic profile roller,which is rolling over a flat plane,is given The analysis takes account of sideways fl...An account of numerical solutions to the isothermal and flooded elastohydrodynamic lubrication(EHL)of a logarithmic profile roller,which is rolling over a flat plane,is given The analysis takes account of sideways flow of lubricant in the inlet region of the contact When the results are presented in suitable non dimensional groups,it is shown that more uniformly pressure and shape of the film distributing in axial direction is taken place under light loading As the increase of the load,the end closure is displayed and the oil pressure rises sharply at the ends The seal action formed by the end closure makes the film thickness a little And the minimum film thickness is transferred from the central to the ends and the value is reduced rapidly As the increase of the speed,the end closure becomes much serious The optimum crowning value obtained in EHL state is larger than the design value obtained in elastostatic contact state for the same working conditions In order to verify the correctness of theory,optical interferometry is applied to measure the oil film thickness between a logarithmic profiled roller and a glass plate under pure rolling conditions It is found the agreement between numerical solutions and experiments is very good.展开更多
In this paper, the effect of the grinding undercut of the raceways on the longitudinal pressure distribution of the profiled rollers, which are the most popular axial profile employed by the bearing manufacturers, was...In this paper, the effect of the grinding undercut of the raceways on the longitudinal pressure distribution of the profiled rollers, which are the most popular axial profile employed by the bearing manufacturers, was discussed. Based on the profiled roller geometrical equations and numerical calculation of three dimensional elastic contact problems of finite length, a new numerical method for calculating the crown drop evaluation considering the effect of grinding undercut was used. The analyses of two structure case, that roller length is greater or less than raceway width, were carried out and compared with each other. The Results show that the width of grinding undercut must be considered in determining the crown drop of rollers.展开更多
基金funded by the twelfth five-year projects of China for science and technology under Contract D50-0109-12-001the Key Innovational Program of Shanghai Municipal Education Commission(No.11ZZ89)
文摘The objective of this study was to investigate the grease-lubricated film-forming mechanisms in the finite line contact and to improve the grease-lubricated finite line contact’s film-forming capacity.An elastohydrodynamic lubrication(EHL) test rig with two interferometry microscopes,which could simultaneously monitor two different contact locations in the finite line contact,was constructed in order to study the influences of the grease thickener formulation on the film thickness and lubrication condition.By using the relative light intensity method,the thickness maps of the grease-lubricated film were calculated from the interferometer images captured by the two microscopes.The test results revealed that the grease thickener’s formulation had remarkable effects on film formation and the perturbation of film thickness.For the lithium-based grease,the film’s thickness near the two ends of the roller was prone to severe perturbation caused by the conglomeration of clumps that were hard to shear.For the aluminum-complex-based grease,the fibers tended to accumulate in the middle of the roller rather than at the two ends.The urea-based grease could be easily sheared into smaller particles.In addition to the straight-line profile rollers,the logarithmic profile rollers were tested and found to effectively enhance the axial grease flow,increase the axial shear stress,and thus shear more fibers into particles within the contact area.
基金This project is supported by National Natural Science Foundation of China (No.59475037).
文摘An account of numerical solutions to the isothermal and flooded elastohydrodynamic lubrication(EHL)of a logarithmic profile roller,which is rolling over a flat plane,is given The analysis takes account of sideways flow of lubricant in the inlet region of the contact When the results are presented in suitable non dimensional groups,it is shown that more uniformly pressure and shape of the film distributing in axial direction is taken place under light loading As the increase of the load,the end closure is displayed and the oil pressure rises sharply at the ends The seal action formed by the end closure makes the film thickness a little And the minimum film thickness is transferred from the central to the ends and the value is reduced rapidly As the increase of the speed,the end closure becomes much serious The optimum crowning value obtained in EHL state is larger than the design value obtained in elastostatic contact state for the same working conditions In order to verify the correctness of theory,optical interferometry is applied to measure the oil film thickness between a logarithmic profiled roller and a glass plate under pure rolling conditions It is found the agreement between numerical solutions and experiments is very good.
文摘In this paper, the effect of the grinding undercut of the raceways on the longitudinal pressure distribution of the profiled rollers, which are the most popular axial profile employed by the bearing manufacturers, was discussed. Based on the profiled roller geometrical equations and numerical calculation of three dimensional elastic contact problems of finite length, a new numerical method for calculating the crown drop evaluation considering the effect of grinding undercut was used. The analyses of two structure case, that roller length is greater or less than raceway width, were carried out and compared with each other. The Results show that the width of grinding undercut must be considered in determining the crown drop of rollers.
