油润滑条件下减摩织构表面的优化设计

发布时间：2018-06-15 05:01

本文选题：表面织构 + 流体润滑　；参考：《中国矿业大学》2015年博士论文

【摘要】：机械设备接触表面间的摩擦问题直接影响设备的能量损耗、失效时间及可靠性,如何减小机械磨损,提高能量效率和延长失效时间是机械行业的重要研究课题。近年来,表面织构作为一种表面处理技术在减摩抗磨领域显现出了较大的优势。通过对零件接触表面进行表面织构的优化设计,可以有效改善润滑状态,减小摩擦磨损。为进一步丰富表面织构领域的科学研究,本文在传统织构研究的基础上通过理论建模和试验研究方法研究了多织构位置排布及各向异性织构形貌的排布模式等因素对润滑摩擦性能的影响,同时对具有复杂嵌套结构的织构表面的润滑摩擦特性进行了深入研究。首先,基于常见的球冠状织构单元建立了CFD流体动压润滑模型,利用高性能科学计算平台计算得到了Navier-Stokes方程的数值解,详细讨论了织构半径、深度、面积率及相对滑动速度对摩擦系数和动压承载能力的影响。结果发现摩擦系数与面积比和深度成反比,其中深度对摩擦系数的影响更大,而动压承载能力则主要与织构深度和相对滑动速度有关,随着深度的增加动压承载能力逐渐增加,在无量纲深度达到15时承载能力达到最大。然后,利用数值仿真方法建立了基于多织构单元相互作用的流体动压润滑模型,研究了圆柱形凹坑织构单元的位置偏移率对摩擦学性能的影响,并采用正交设计方法研究了织构单元的深度、半径、位置偏移率及相对滑动速度对摩擦系数和动压承载能力的影响。结果发现织构单元位置偏移率对摩擦副表面间的动压承载能力有十分显著的影响,当位置偏移率由0增加到0.5时,压力系数的增幅达34.9倍,与此同时摩擦系数仅增加约0.59%。同时发现,适当增加圆柱状织构单元的面积可以在有效增加动压承载能力的同时减小摩擦力。对于具有圆对称结构的圆柱状凹坑,不需要考虑织构单元的倾角因素,而对于像椭圆形织构单元这种具有各向异性结构特征的织构而言,其倾角、位置偏移率及排布模式对摩擦学性能的协同影响则是织构优化设计必须要考虑的重要因素。正交设计的具有不同面积、倾角、位置偏移率及排布模式的椭圆织构表面的CFD仿真结果发现增加椭圆织构单元的面积能显著降低织构表面的摩擦系数,而椭圆长轴与相对滑动方向一致时摩擦系数最小。织构单元的倾角和位置偏移率对动压承载能力的提升有显著贡献。摩擦磨损试验结果同样发现椭圆柱状织构的倾角和位置偏移率对摩擦力有较大影响,而椭圆织构的最佳单元间距为1500μm。低速轻载工况条件下,织构倾角取0°减摩效果最好,而高速重载条件下取90°摩擦力最小。通过对三种不同织构排布模式的对比研究发现P2排布模式的织构表面具有更优越的减摩性能。圆环状织构是一种具有复杂嵌套结构的织构单元,其环状结构兼具离散的凹坑织构和连续的凹槽织构的结构特点。对单一织构单元的数值仿真研究结果显示,在相同面积比条件下圆环状织构的减摩性能优于传统的圆柱状织构,并且随着织构单元面积比的增加摩擦系数逐渐减小,同时流线分析结果表明圆环状织构在吸纳磨屑方面较圆柱状织构更有优势。为了验证理论结果的可靠性在可变载荷摩擦磨损试验机上测试了圆环状织构表面的摩擦力,试验结果发现圆环宽度对摩擦力有较大影响,宽度为200μm的圆环织构具有最优减摩效果,同时摩擦力随着织构单元的位置偏移率的增大而逐渐减小。圆环状织构表面的摩擦性能对织构的设计参数较为敏感,不同织构参数的织构表面的摩擦力可以大于或小于相应光滑表面。
[Abstract]:The friction between the contact surfaces of the mechanical equipment directly affects the energy loss, failure time and reliability. How to reduce the mechanical wear, improve the energy efficiency and prolong the failure time is an important research topic in the machinery industry. In recent years, the surface texture has shown great advantages in the field of antifriction and wear reduction as a surface texture technology. The optimal design of surface texture on the surface of the parts can effectively improve the lubrication state and reduce friction and wear. In order to further enrich the scientific research in the field of surface texture, the paper studied the position arrangement and anisotropic texture of multi texture on the basis of the theoretical modeling and Experimental Research on the basis of the traditional texture research. The influence of the layout mode of the appearance on the lubrication friction properties and the lubrication and friction characteristics of the texture surface with complex nested structure were studied. First, the CFD fluid dynamic lubrication model was established based on the common spherical coronal texture unit, and the Navier-Stokes equation was calculated by the high performance computing platform. The influence of the texture radius, depth, area rate and relative sliding velocity on the friction coefficient and the bearing capacity of the dynamic pressure is discussed in detail. The results show that the friction coefficient is inversely proportional to the area ratio and depth, and the depth has greater influence on the friction coefficient, while the dynamic loading capacity is mainly related to the texture depth and relative sliding velocity. The bearing capacity of dynamic pressure increases gradually, and the bearing capacity reaches the maximum when the dimensionless depth reaches 15. Then, the hydrodynamic lubrication model based on the interaction of multi texture elements is established by numerical simulation. The influence of the position deviation rate on the tribological properties of the cylindrical concave texture unit is studied and the orthogonal design is used. The influence of the depth, radius, position deviation and relative sliding velocity of the texture element on the friction coefficient and the bearing capacity of the dynamic pressure is studied by the design method. The results show that the position migration rate of the texture unit has a significant influence on the dynamic loading capacity of the friction pair. When the position migration rate increases from 0 to 0.5, the increase of the pressure coefficient is increased. At the same time, the friction coefficient is up to about 0.59%. at the same time, at the same time, the coefficient of friction is only about 0.59%.. It is found that the proper increase in the area of the cylindrical texture unit can reduce the friction force while increasing the dynamic loading capacity. For cylindrical concave with circular symmetry, it is not necessary to consider the inclination factor of the texture unit, but for the elliptical texture unit. In the case of texture with anisotropic structure, its inclination, position migration rate and the synergistic effect of the arrangement mode on the tribological properties are important factors to be considered in the optimization design of texture. The CFD simulation results of orthogonal design with different area, angle, position deviation and pattern type elliptical texture are found to be increased. The area of the elliptical texture unit can significantly reduce the friction coefficient of the texture surface, and the friction coefficient is the smallest when the elliptical long axis is the same as the relative sliding direction. The inclination and position offset of the texture unit have a significant contribution to the lifting capacity. The friction and wear test results also have the inclination and position deviation of the elliptical cylindrical texture. The rate has a great influence on the friction force, while the optimal unit spacing of the elliptical texture is 1500 m. low speed light load condition, and the texture dip angle is best with 0 degree reduction, while the friction force of 90 degrees is the smallest under the high speed heavy load condition. The texture surface of the P2 layout mode is superior by comparing the three different texture layout modes. The circular texture is a texture unit with complex nested structure, with a circular structure with a discrete concave texture and a continuous groove texture. Numerical simulation of a single texture unit shows that the friction reduction performance of circular circular texture is better than that of the traditional cylindrical fabric under the same area ratio condition. The friction coefficient gradually decreases with the increase of the area ratio of the texture element, and the flow line analysis shows that the circular texture is more advantageous than the cylindrical texture in absorbing the debris. In order to verify the reliability of the theoretical results, the friction force of the circular texture surface is tested on the variable load friction and wear testing machine. The test results are also tested. It is found that the ring width has a great influence on the friction force. The annular texture with a width of 200 m has the best antifriction effect. At the same time, the friction force gradually decreases with the increase of the position migration rate of the texture element. The friction properties of the circular texture surface are more sensitive to the design parameters of the texture. The frictional force on the texture surface with different texture parameters can be found. To be larger than or less than the corresponding smooth surface.
【学位授予单位】：中国矿业大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TH117

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