制造误差对多孔质静压轴承静动态特性的影响规律研究

发布时间：2018-11-10 12:08

【摘要】：气体静压轴承是超精密机床的重要支撑部件,具有摩擦损耗小、无污染、精度高、寿命长等优点。随着超精密技术的不断发展,对气体静压轴承承载特性、回转精度和稳定性的要求也不断提高。多孔质气体静压轴承以其稳定性好、承载力高和精度更优等特点,正逐步替代小孔节流形式的静压轴承成为国内外学者研究的重点。然而,制造误差对多孔质气体静压轴承静动态特性影响规律的研究仍然存在困难,是进一步提高超精密机床精度亟待解决的问题。针对这一问题,本文在分析国内外气体静压轴承的研究理论及方法的基础上展开研究工作,旨在探求多孔质气体静压主轴制造误差的表征方法、制造误差对静动态特性的影响规律。本文主要研究内容如下:(1)改进了多孔质气体静压轴承静动态特性的数值求解方法。基于流体力学基本方程,结合多孔质内部流场规律,建立了多孔质气体静压轴承的求解方程;基于流体力学软件,建立了多孔质气体静压轴承的数值求解模型;基于动网格技术改进了轴承转子的动态回转精度预测方法,通过将转动速度转化为线速度,添加至Naiver-Stokes方程动量源项的方式解决了回转运动网格畸变问题,实现了对主轴运动过程的动态模拟,这将有利于推动静压轴承的影响规律的研究工作;(2)研究了制造误差的表征方法及其对轴承静态特性的影响规律。基于实验测量与数学函数拟合的方式,对不同形式的制造误差进行了表征,并嵌入到轴承的数值计算模型中;计算了不同形式的制造误差对多孔质气体静压轴承的静态特性的影响规律,得到了制造误差的类型与幅值对径向及轴向承载力和刚度的变化关系;静态特性实验验证了考虑制造误差时的计算结果更接近真实值。上述工作将有助于多孔质气体静压轴承的结构设计。(3)分析了不同制造误差对多孔质气体静压轴承动态特性的影响规律。基于轴承转子的回转运动分析,研究了动不平衡量及圆度误差对回转精度的影响规律;通过比较有无制造误差时,轴承间隙内部的压强分布、速度矢量及承载力的变化规律,分析了圆度误差的动态影响机理;通过将圆柱度误差对轴向的影响转化为力的形式,采用动网格技术将其嵌入到轴向求解方程中,求解得到了其对轴向动态特性的影响规律;最后,回转精度实验测试结果验证了上述有关结论,上述研究工作将有助于推动提升超精密机床精度的研究。
[Abstract]:Aerostatic bearing is an important supporting part of ultra-precision machine tools. It has the advantages of low friction loss, no pollution, high precision and long life. With the continuous development of ultra-precision technology, the bearing characteristics, rotary accuracy and stability of aerostatic bearing have been improved. Because of its good stability, high bearing capacity and better precision, porous gas hydrostatic bearing is gradually replacing the hydrostatic bearing with small orifice throttle form, which has become the focus of scholars at home and abroad. However, it is still difficult to study the influence of manufacturing errors on static and dynamic characteristics of porous aerostatic bearings, which is an urgent problem to improve the accuracy of ultra-precision machine tools. In order to solve this problem, based on the analysis of the theory and method of aerostatic bearing at home and abroad, the purpose of this paper is to find out the characterization method of manufacturing error of porous gas hydrostatic spindle. The influence of manufacturing error on static and dynamic characteristics. The main contents of this paper are as follows: (1) the numerical solution of static and dynamic characteristics of porous aerostatic bearing is improved. Based on the basic equations of fluid mechanics and the law of internal flow field of porous mass, the solution equation of porous gas hydrostatic bearing is established, and the numerical solution model of porous gas static bearing is established based on hydrodynamic software. Based on the dynamic mesh technology, the dynamic rotation accuracy prediction method of the bearing rotor is improved. By transforming the rotational velocity into the linear velocity and adding it to the momentum source term of the Naiver-Stokes equation, the problem of the rotating mesh distortion is solved. The dynamic simulation of the spindle motion process is realized, which will be beneficial to the research of the influence law of the hydrostatic bearing. (2) the characterization method of manufacturing error and its influence on the static characteristics of bearing are studied. Based on the experimental measurement and mathematical function fitting, the manufacturing errors of different forms are characterized and embedded into the numerical calculation model of bearings. The influence of different manufacturing errors on the static characteristics of porous gas static bearing is calculated. The relationship between the type of manufacturing error and amplitude on radial and axial bearing capacity and stiffness is obtained. The static characteristic experiments show that the calculated results are closer to the real value when the manufacturing error is taken into account. The above work will contribute to the structural design of porous gas hydrostatic bearing. (3) the influence of different manufacturing errors on the dynamic characteristics of porous gas hydrostatic bearing is analyzed. Based on the rotary motion analysis of the bearing rotor, the influence of dynamic unbalance and roundness error on the rotary accuracy is studied. The dynamic influence mechanism of roundness error is analyzed by comparing the pressure distribution, velocity vector and bearing capacity of bearing clearance with or without manufacturing error. By transforming the influence of the cylinder error to the axial force, the dynamic grid technique is used to embed it into the axial solution equation, and the law of its influence on the axial dynamic characteristic is obtained. Finally, the experimental results of rotary accuracy verify the above conclusions, which will help to improve the precision of ultra-precision machine tools.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH133.36

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