动静压轴承加工质量及弹性变形对其性能的影响研究

发布时间：2018-05-08 16:13

本文选题：动静压轴承 + 加工质量　；参考：《重庆大学》2012年硕士论文

【摘要】：动静压轴承是一种既综合了液体动压和静压轴承的优点，又克服了两者缺点的新型油膜轴承。目前，研究者对动静压轴承基本特性进行了大量研究工作，但未考虑加工质量和弹性变形的影响。然而，研究表明加工质量所产生的误差和弹性变形量与油膜厚度的数量级相近，对其动静态特性影响显著。因此，本论文基于动静压轴承的基本理论，研究上述因素对轴承性能的影响，不仅有利于完善动静压轴承的设计理论，也为动静压轴承的加工制造提供理论指导。本文以雷诺方程为基础建立了动静压轴承油膜性能的数学模型，采用有限差分方法对其数学模型进行离散化，运用现代数值分析工具MATLAB进行编程，对理想轴承的动静态特性进行研究。结果表明：当主轴的偏心率较小时，动压效应较弱，主要以静压来满足轴承的工作要求；当主轴偏心率较大时，，动压效应较强，动压则成为轴承的主要压力来源。此外，在动载荷作用下，主轴轴心位置不断变化，其运动速度可以分解为偏心距变化率和偏位角变化率，前者会产生挤压效应，后者则增加楔效应的作用。为便于直观描述轴承的工作特性，还利用了准稳定轴承法绘制轴心的运动轨迹曲线。在上述理想轴承动静态特性研究的基础上，开展了加工质量对动静压轴承性能影响的研究。经研究得出：在轻载工况下，因为油膜厚度比较大，所以表面粗糙度对油膜性能的影响很小，可以忽略不计；在重载工况下，要求很高的油膜压力来提供轴承的承载力，如果过多的依赖动压效应来提高油膜压力，势必会增大偏心率，同时降低最小油膜厚度，而油膜厚度和表面不平度的数量级相近，就很容易出现油膜厚度过薄的情况，甚至出现干摩擦，影响油膜的正常使用。此外，本文还分析了尺寸公差及形状公差对轴承性能的影响规律。尺寸公差和形状公差都将引起轴承油膜间隙的变化。在选择尺寸公差时，尽量使公差带所确定的初始间隙更小，以便更有效的发挥动静压轴承的能力。在讨论形状误差时，主要对带椭圆内表面的轴承进行研究。当轴承内表面的椭圆形状绕主轴的轴心线逆时针旋转时，轴承的承载力先减小后增大再减小，尤其在长轴与偏位线垂直时，承载能力最强。最后，开展了轴与轴瓦弹性变形对动静压轴承性能影响的研究。经研究得出：在外载荷作用下主轴和轴瓦产生弹性变形，影响了油膜压力分布和厚度分布。轴的弯曲变形和轴瓦内表面的挤压变形都会使轴承的承载力下降。研究结果表明：轴与轴承的加工质量和弹性变形对动静压轴承性能的影响主要是通过改变轴承油膜间隙从而引起油膜性能的变化来体现的。论文研究结果对于指导轴承的设计和实际应用具有重要的参考意义。
[Abstract]:The hydrostatic bearing is a new type of oil film bearing which combines the advantages of hydrostatic and hydrostatic bearings and overcomes their shortcomings. At present, researchers have done a lot of research work on the basic characteristics of the static and static bearing, but the effect of machining quality and elastic deformation has not been taken into account. However, it is shown that the error and elastic deformation caused by the processing quality are similar to the oil film thickness, and the dynamic and static characteristics are significantly affected. Therefore, based on the basic theory of the hydrostatic bearing, this paper studies the influence of the above factors on the bearing performance, which is not only helpful to perfect the design theory of the static and static bearing, but also provides theoretical guidance for the manufacture of the static and static bearing. Based on Reynolds equation, the mathematical model of oil film performance of hydrostatic bearing is established in this paper. The mathematical model is discretized by finite difference method and programmed by modern numerical analysis tool MATLAB. The static and static characteristics of ideal bearings are studied. The results show that when the eccentricity of the spindle is small, the dynamic pressure effect is weak, and the hydrostatic pressure is mainly used to meet the requirements of the bearing, and when the spindle eccentricity is large, the dynamic pressure effect is stronger, and the dynamic pressure becomes the main pressure source of the bearing. In addition, under the action of dynamic load, the axial position of the spindle is constantly changing, its velocity can be decomposed into eccentricity change rate and offset angle change rate, the former will produce extrusion effect, and the latter will increase the effect of wedge effect. In order to intuitively describe the working characteristics of the bearing, the quasi-stable bearing method is also used to draw the trajectory curve of the axis center. Based on the study of the dynamic and static characteristics of the ideal bearing, the effect of machining quality on the performance of the hydrostatic bearing is studied. It is concluded that under the light load condition, the surface roughness has little effect on the oil film performance because of the large oil film thickness, and under heavy load condition, the high oil film pressure is required to provide bearing capacity. If the oil film pressure is increased by relying too much on the dynamic pressure effect, the eccentricity will be increased and the minimum oil film thickness will be reduced at the same time. If the oil film thickness is close to the order of magnitude of the surface irregularity, it is easy to have the oil film thickness too thin. Even dry friction, affecting the normal use of oil film. In addition, the effect of dimension tolerance and shape tolerance on bearing performance is analyzed. Size tolerance and shape tolerance will cause the change of oil film clearance. When choosing the dimension tolerance, the initial clearance determined by the tolerance belt is smaller, so that the ability of the static and static bearing can be brought into play more effectively. When discussing the shape error, the bearing with elliptical inner surface is studied. When the elliptical shape of the inner surface of the bearing rotates counterclockwise around the axis line of the spindle, the bearing capacity of the bearing decreases first and then increases and then decreases, especially when the long axis is perpendicular to the offset line, the bearing capacity is the strongest. Finally, the influence of elastic deformation of shaft and bearing bush on the performance of static and dynamic bearing is studied. It is concluded that the elastic deformation of spindle and bush under external load affects the distribution of oil film pressure and thickness. The bearing bearing capacity will be reduced by bending deformation of shaft and extrusion deformation of bearing inner surface. The results show that the influence of machining quality and elastic deformation of shaft and bearing on the performance of static and dynamic bearing is mainly reflected by changing the oil film clearance of bearing and causing the change of oil film performance. The results of this paper have important reference significance for guiding the design and practical application of bearings.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH133.3

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