新型动静压转台静动态特性分析

发布时间：2018-07-06 21:03

本文选题：回转台 + 动静压轴承　；参考：《山东大学》2017年硕士论文

【摘要】：回转工作台是大型、重型数控加工设备的主要部件,其性能优劣影响着设备的加工质量和运行效率。而在转台中,推力轴承是其关键部件。在大型回转台中,采用大型重载推力滚珠轴承不仅制造困难、成本高而且磨损严重,目前装备制造业中主要采用静压推力轴承。动静压轴承是在综合动压轴承和静压轴承的优点后而开发出来的的新型轴承,具有启动力矩小,油膜刚性高,承载能力强和性能可靠等优点。当动静压轴承工作在一定转速时,可以降低供油压力,从而显著地减小供油系统的功耗。本文对一种新型动静压转台的性能进行了研究,主要对动静压转台的压力分布建模进行了计算,研究了工作条件和结构参数对静态、动态特性的影响,并将采集得的实验数据和计算结果进行了相应的对比,具体工作内容如下:(1)对动静压转台的油腔结构进行了介绍,建立螺旋油楔的油膜厚度方程,综合考虑雷诺方程和流量连续性方程,采用有限元法对动压螺旋油楔区域的油膜压力进行了计算。与相关文献的计算结果进行了对比,验证了所编制的MATLAB有限元程序的正确性与可靠性。联立求解雷诺方程与流量连续性方程,建立了转台静态特性计算模型。对回转台承载力、摩擦力矩和流量等静态特性进行了计算。(2)分析了固定负载条件下转速与供油压力分别变化对转台静态特性的影响,研究槽深、螺旋角、槽数、槽宽比、槽径比和螺旋油楔径向长度比等结构参数对转台静态特性的影响规律,综合考虑总承载力和动压比对结构参数的选取范围进行了推荐。考虑油膜厚度较小时螺旋油楔存在的供油不足的情况,提出了一种结构改进的方法,研究结果表明,改进后的结构可以解决一定工作条件下螺旋油楔供油不足的问题,并能显著提高承载力,同时可以降低静压油腔封油面的加工精度。(3)考虑挤压效应对稳态雷诺方程和流量平衡方程进行了修正,采用差分法对转台刚度系数和阻尼系数进行了计算,分析工作条件和结构参数对动态特性的影响,为转台油腔结构参数的优化提供了参考。(4)介绍了实验系统的构成和传感器的布置,对涡流传感器的实际初始安装间隙进行了标定。对于采集的实验数据采用理想低通滤波器进行了处理,并和计算结果进行了对比,结果表明计算结果和实验数据吻合较好,计算方法较为可靠。本文完成了动静压转台的压力分布建模与静动态特性分析,为以后的结构优化与运动平稳性分析等进一步的研究打下理论基础。
[Abstract]:Rotary table is the main component of large and heavy NC machining equipment, and its performance affects the machining quality and operation efficiency of the equipment. In the turntable, thrust bearing is the key component. In the large scale rotary table, it is difficult to manufacture large heavy load thrust ball bearings, high cost and serious wear. At present, hydrostatic thrust bearings are mainly used in the equipment manufacturing industry. The hydrostatic bearing is a new type bearing which is developed after combining the advantages of hydrodynamic bearing and static bearing. It has the advantages of small starting moment, high oil film rigidity, strong bearing capacity and reliable performance. When the dynamic and static bearing is working at a certain speed, the fuel supply pressure can be reduced, and the power consumption of the fuel supply system can be significantly reduced. In this paper, the performance of a new type of dynamic and static pressure turntable is studied. The pressure distribution of the table is calculated, and the influence of working conditions and structural parameters on the static and dynamic characteristics is studied. The experimental data are compared with the calculated results. The main contents are as follows: (1) the structure of the oil chamber is introduced, and the oil film thickness equation of the spiral oil wedge is established. Considering Reynolds equation and flow continuity equation, the oil film pressure in the hydrodynamic spiral wedge region is calculated by finite element method. The validity and reliability of the MATLAB finite element program are verified by comparing with the calculation results of related literatures. The static characteristic calculation model of turntable is established by solving Reynolds equation and flow continuity equation simultaneously. The static characteristics such as bearing capacity, friction moment and flow rate of rotary table are calculated. (2) the influence of the change of rotational speed and oil supply pressure on the static characteristics of turntable under fixed load is analyzed, and the groove depth, spiral angle, slot number and slot width ratio are studied. The influence of structural parameters such as groove diameter ratio and radial length ratio of spiral oil wedge on the static characteristics of turntable is studied. The selection range of structural parameters is recommended considering the total bearing capacity and dynamic pressure ratio. Considering the shortage of oil supply in spiral wedge with small thickness of oil film, a method of structure improvement is proposed. The results show that the improved structure can solve the problem of insufficient oil supply in spiral wedge under certain working conditions. It can improve the bearing capacity and reduce the machining accuracy of the seal surface of the hydrostatic oil chamber. (3) considering the extrusion effect, the steady state Reynolds equation and the flow equilibrium equation are modified. The stiffness coefficient and damping coefficient of turntable are calculated by difference method, and the influence of working conditions and structural parameters on dynamic characteristics is analyzed. It provides a reference for the optimization of the structural parameters of the turntable oil chamber. (4) the structure of the experimental system and the arrangement of the sensor are introduced, and the actual initial installation clearance of the eddy current sensor is calibrated. The collected experimental data are processed by the ideal low-pass filter and compared with the calculated results. The results show that the calculated results are in good agreement with the experimental data and the calculation method is more reliable. In this paper, the pressure distribution modeling and static and dynamic characteristics analysis of the static and static pressure turntable are completed, which lays a theoretical foundation for the further research on structure optimization and motion stability analysis.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG659

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