| There are a large number of friction pairs between the mechanical surfaces,friction will lead to wear of mechanical equipment,and then cause mechanical equipment failure.Lubrication and surface texture are important measures to reduce friction and wear,and also a key point to improve energy utilization.In this thesis,the point contact mixed lubrication and surface texture lubrication are studied,which is of great significance to the friction reduction between parts.In this thesis,the contact of the micro convex body was simplified by the contact between the ball and the rough plane.A point contact lubrication model based on the unified Reynolds equation was established to solve the film thickness distribution and pressure distribution of the point contact lubricant film in the pure rolling state.The film thickness and pressure distribution of transverse,longitudinal and isotropic surface texture,as well as the influence of different surface texture amplitudes on lubrication characteristics were calculated and compared under different viscosity.The results show that the higher the ambient viscosity is,the easier it is to form lubricating oil film,and the thicker the film thickness is;the lower the ambient viscosity is,the better the expansibility is,and the larger the lubricating range is;the higher the viscosity is,the pressure distribution is uniform and compact;under the same working condition,the isotropic surface texture has the strongest ability to form lubricating oil film,the thickest film thickness,the longitudinal second,the transverse smallest,but Under the condition of the same viscosity,with the increase of the amplitude,the thickness of the central film decreases and the contact area ratio increases.In engineering practice,the viscosity of lubricating oil is selected according to the processing method and texture direction,which provides reference for engineering practice.In order to explore the influence of textured surface on lubrication and friction more comprehensively,this thesis designed a kind of Kite-shaped surface texture.Firstly,ANSYS Fluent was used for simulation calculation,then laser marking machine was used to texturize the quenched 40Cr,and finally friction and wear testing machine was used for friction and wear experiment.The oil film bearing capacity and friction coefficient of each parameter(area ratio,inclination angle,depth,angle between sides,texture size)of Kite-shaped texture were studied The significance of the influence of each factor on the friction coefficient was analyzed.The results show that the experimental results are consistent with the simulation results.Considering single factor,the friction coefficient tends to decrease first and then increase as the increase of area ratio of Kite-shaped texture,there is an optimal area ratio to minimize the friction coefficient Meanwhile,the friction coefficient is minimized when the inclination angle is set to 180°.Furthermore,the friction coefficient tends to decrease first and then increase as the increase of depth of Kite-shaped texture,there is an optimum depth to minimize the friction coefficient Obtained results show that as the increase of angle between sides of Kite-shaped texture,the friction coefficient tends to decrease first and then increase,there is an optimal angle between sides to minimize the friction coefficient.Moreover,the friction coefficient tends to decrease first and then increase as the increase of size of Kite-shaped texture,there is an optimal texture size to minimize the friction coefficient.Considering the results,the order of the influence of the five parameters on the friction coefficient is depth,texture size,angle of inclination,angle between sides and area ratio.The relationship between the depth and texture size of Kite-shaped texture and the friction coefficient is nearly linear.When the Kite-shaped surface texture is used to reduce friction in practice,the theoretical and experimental basis is provided for parameter selection and parameter adjustment. |
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