Theoretical And Experimental Study On Friction Lubrication Characteristics Of Rough Surfaces With Micro-grooves

The technology of surface texture can effectively improve the friction and lubrication performance between mechanical components,and it has become a hot research field of mechanical engineering.As a common texture type,micro-grooves not only can improve the effect of hydrodynamic pressure,but also can dredge lubricants to achieve the purpose of rapid oil distribution,which can effectively improve the surface tribological performance and cause extensive attention among scientific researchers.In recent years,researches on micro-texturing mostly focus on the effects of texture forms and geometric parameters on tribological properties,but do not fully consider the effect of initial surface roughness on micro-texture surface.However,when the surface roughness peak and average film thickness of the lubricating oil film are on the same order of magnitude,the effect of surface roughness on the lubrication performance at this time is crucial.Therefore,it has important scientific significance and practical engineering value to study the tribological properties of micro-grooves textured surface.Firstly,the sinusoidal model rough peakis used to simulate the surface roughness.Based on the JFO cavitation boundary of mass conservation law,the deterministic model for hydrodynamic lubrication of micro-grooves textured bidirectional roughness surface is established.After that,the multi-grid method is used to solve the deterministic model to obtain the pressure distribution map of lubricant film.Finally,the influence of the peak height,wavelength of bidirectional sinusoidal roughness model and micro-grooves textured surface parameters on the average oil film pressure is discussed.The results show that the size of the calculation area has an important influence on the accuracy of the numerical calculation.The larger the calculation area,the higher the accuracy of results.When the effect of micro-groove texture on hydrodynamic lubrication is studied by numerical simulation method,the influence of the roughness peak of sinusoidal model on the lubrication performance is affected to a certain extent.As the peak height increases,the carrying capacity of the oil film gradually decreases,and the optimal micro-groove texture depth is affected by the roughness height.Under the condition of bidirectional rough surface,there are optimal micro-groove geometric parameters to maximize the oil film carrying capacity.Then,the unidirectional sinusoidal model was used to simulate the unidirectionaltexture structure of surface roughness,and a deterministic model of micro-grooves textured unidirectional rough surface hydrodynamic lubrication is established.By analyzing the change of the average oil film pressure curve,the influence of geometric parameters of micro-groove texture on average oil film pressure distribution under unidirectional sinusoidal roughness is studied,and compared with the results of bidirectional sinusoidal curve characterization.The results show that the effect of geometrical parameters of micro-grooves on the average oil film pressure is less affected by the change of roughness model.The average oil film pressure of the micro-grooves textured unidirectional rough surface is slightly higher than that of the bidirectional roughness simulation.Finally,The study focused on the micro-grooves textured rough surfaces.Reciprocating friction test was performed on the Rtec friction and wear tester,and the Stribeck curve was plotted based on the test results.The results showed that the ideal performance of friction reduction of the textured surfaces can be obtained by optimizing the roughness according to the load and speed conditions.An interesting finding in the present paper is the existence of an optimal roughness that minimizes the friction coefficient of the textured surface,and the optimal roughness is depend on the load,speed and groove depth.Numerical simulations and experimental studies have shown that roughness affects the lubricating properties of micro-grooves textured surface and can not simply ignore the effects of surface roughness.The results of this paper play a guiding role in the theoretical research and engineering application of surface texture.