Research On Surface Topography Characteristics And Tribological Property Of Part Point-grinded

There is wheel slant angle between the axis of the wheel and the axis of the part in the process of point-grinding, so the surface topography of the cylindrical part point-grinded is different from the part common cylindrical grinded, the surface integrity is fine and the surface texture direction is changeable. The surface topography of the part point-grinded has crucial effect on the tribological properties and contact characteristics.This paper was integrated with the project (51075065):The control technology and theory research of the surface integrity based on the point-grinding combined machining which is supported by national natural science foundation. In this paper, the influence rule of the point-grinding machining parameters on the surface topography is analyzed and the part point-grinded is characterized properly, the effects of the part surface topography point-grinded on the tribological properties under fluid lubrication condition and under the dry sliding contact condition are researched, the relationship between the surface texture and the load capacity of the film under fluid lubrication condition and the influence rule of the surface texture on the contact stress and contact length under dry sliding contact condition are researched. The design and realization method of the part surface topography point-grinded are proposed based on the above theoretical analysis and experimental research. The specific research contents are as follows:(1) The influence rule of the point-grinding machining parameters on the surface roughness and surface texture is analyzed. The influence rule of the surface texture characteristics on the evaluation parameters of the surface roughness is analyzed by experiment, and the research shows that the fluctuation range of the profile curve is the least and the surface roughness value is the least when surface texture direction angle is 10°～15°.(2) The influence rule of the surface texture direction on the surface fractal dimension and scale coefficient is researched and the theoretical computing formula of the surface fractal dimension and scale coefficient are achieved by theoretical analyzing and experimental researching based on the characteristics of the point-grinding after the traditional characterization parameters of the surface roughness, estimation method of the fractal dimension and the computation method of the scale coefficient have been analyzed. The experimental results show that:the surface fractal dimension is the largest and the scale coefficient is the least when the surface texture direction is 60°; the surface fractal dimension is smaller and the scale coefficient is the biggest when the surface texture direction is 30°.(3) The equation of the lubrication fluid film thickness and the Reynolds equation of the single micro-peak considering the surface texture are deduced theoretically, the boundary condition of the Reynolds equation is determined, the Reynolds equation is non-dimensionalized and numerical solution of the Reynolds equation is achieved. The effect of the surface texture direction point-grinded on the average film pressure, carrying capacity and the friction is analyzed, the effect of the minimum film thickness on the carrying capacity and friction is also analyzed according to the theoretical research and numerical solution.(4) The influence rule of the surface texture on the abrasive resistance is gained by analyzing the effect of the surface texture direction on the surface bearing length ratio, the influence rule of the surface texture direction on the surface bearing length is analyzed by experiment. The contact mechanics model of the part point-grinded is constituted based on fractal theory, the relation equation between real contact length and the contact stress is constituted. The contact mechanics model is analyzed by applying Matlab, the relation between the stress-real contact length curve and each variable.(5) The effects of the surface texture direction on the tribological property under fluid lubrication condition and dry sliding contact condition are analyzed by experiment. The results show that the friction coefficient of the part is smaller when the surface texture direction is 30° and the load and the velocity are reasonable under the fluid lubrication condition. Under dry sliding contact condition, the fluctuation of friction coefficient is smaller, the value of friction coefficient is smaller, the tribological property of the part is better for the part whose surface texture direction is 30° and 60°; the abrasion loss is the least when the angle of the surface texture direction of the friction pair is 45°.(6) The surface topography design theory under certain working condition is proposed according to the influence rule of the surface texture direction on the tribological property of the part under fluid lubrication condition and dry sliding contact conditions, the surface topography parameters which make the part have optimum tribological property are obtained. The reasonable machining parameters of point-grinding is determined by applying the relation between the surface topography parameters and the machining parameters of the point-grinding, the adaptable surface topography can be obtained.