超高速空气静压电主轴的动静态性能分析与实验研究

发布时间：2018-10-17 13:11

【摘要】：随着电子元器件微型化和各类电器功能复杂化,PCB电路板的集成度也越来越高,PCB板上的微细孔也越来越密集。为了提高密集孔的钻削效率和改善微小孔的钻削质量,在PCB微细孔的钻削过程中,常采用超高速空气静压电主轴来钻削。超高速空气静压电主轴,是以空气静压轴承作为支承元件,能在超高转速下保持较高的回转精度,而且无污染、无磨损、使用寿命长。但是超高速空气静压电主轴的承载力和刚度较小,易出现气锤自激振动和涡动失稳现象,影响着超高速空气静压电主轴的稳定性和可靠运行。本文通过研究空气静压轴承的承载性能、静态稳定性、超高速空气静压电主轴的动静态特性及其影响因素,以掌握超高速空气静压电主轴的设计方法。本文主要从以下几方面进行了研究： 1、通过对气体润滑理论的深入分析,从一般形式的Reynolds方程出发,结合空气静压轴承的实际状况,建立了空气静压轴承气膜压力分布的数学模型,得出空气静压轴承的承载能力。在此基础上,研究轴承结构参数和供气参数共同影响下轴承的静态特性,分析这些参数对承载性能和气锤效应的影响,优选参数必须综合考虑承载力、刚度、耗气量、实际情况。 2、采用ANSYS的CFD模块,分析了超高转速条件下,空气静压轴承的承载性能的变化规律。研究表明：转速增加时,空气静压径向轴承的承载性能明显增加且在不同转速段承载性能的增加不同,但是转速的增加对空气静压止推轴承的承载性能影响较小。 3、从主轴发生涡动失稳的角度,首先研究气膜阻尼系数与偏心、涡动转速和主轴转速之间的关系。研究发现：加大阻尼面、减小气膜厚度、适当增大偏心率、提高主轴涡动转速等方法可增加气膜的阻尼、提高主轴的动态稳定性。然后,根据上述分析结果,推导计算了超高速空气静压电主轴涡动失稳时的极限转速。 4、结合轴承气膜和主轴的实际结构参数,建立轴承气膜和主轴的整体模型,采用气固耦合的方法,研究超高速空气静压电主轴的静态承载性能,确定气膜的等效材料特性,在此基础上进行了超高速空气静压电主轴的动态特性分析,包括模态特性和谐响应分析。研究表明：施加的轴向外载增加时,电主轴的轴向刚度明显增加；施加的径向外载增加时,电主轴的径向刚度比较稳定,增加缓慢；主轴的三个低阶共振频率处于电主轴有效工作转速范围内,在这三个共振频率附近,主轴前端的振幅较大、动态刚度下降很快。加工时,主轴工作转速需要尽量避开共振频率。 5、为了验证超高速静压电主轴动静态特性的仿真分析结果的正确性,最后对超高速空气静压电主轴进行了静刚度实验测试、主轴空转运行实验等相关实验研究,并将理论分析的数据和实验测试的数据进行对比,同时分析了产生误差的原因。
[Abstract]:With the miniaturization of electronic components and the complexity of various electrical functions, the integration of PCB circuit boards is becoming higher and higher, and the micro-holes on PCB boards are becoming more and more dense. In order to improve the drilling efficiency of the dense holes and the drilling quality of the tiny holes, the ultra-high speed air hydrostatic motorized spindle is often used in the drilling process of the PCB micro-holes. The ultra-high speed air hydrostatic motorized spindle takes the air hydrostatic bearing as the supporting element. It can keep high rotary precision at the ultra high speed and has no pollution, no wear and long service life. However, the bearing capacity and stiffness of the super-high speed aerostatic motorized spindle are small, the self-excited vibration and vortex instability of the air hammer are easy to occur, which affects the stability and reliable operation of the ultra-high speed aerostatic motorized spindle. In this paper, the bearing capacity, static stability, static and static characteristics of ultra-high speed aerostatic motorized spindle and its influencing factors are studied in order to master the design method of ultra high speed aerostatic motor spindle. This paper mainly studies from the following aspects: 1, through the deep analysis of the gas lubrication theory, starting from the general form of Reynolds equation, combined with the actual condition of the air static bearing, The mathematical model of film pressure distribution of aerostatic bearing is established, and the bearing capacity of aerostatic bearing is obtained. On this basis, the static characteristics of bearing under the influence of bearing structure parameters and gas supply parameters are studied, and the effects of these parameters on bearing performance and air hammer effect are analyzed. 2. Using the CFD module of ANSYS, the change law of bearing load performance under ultra high speed is analyzed. The results show that with the increase of rotating speed, the bearing capacity of the aerostatic radial bearing increases obviously and the load bearing performance increases differently at different rotational speeds. However, the increase of rotational speed has little effect on the bearing capacity of aerostatic thrust bearing. 3. From the point of view of vortex instability of spindle, the relationship between film damping coefficient and eccentricity, whirling speed and spindle speed is studied firstly. It is found that increasing the damping surface, reducing the thickness of the film, increasing the eccentricity and increasing the swirl speed of the spindle can increase the damping of the film and improve the dynamic stability of the spindle. Then, according to the above analysis results, the limit rotational speed of the superhigh speed aerostatic motorized spindle is deduced and calculated. 4. Combined with the actual structure parameters of the bearing film and the spindle, the integral model of the bearing film and the spindle is established. In this paper, the static load-bearing performance of ultra-high speed air hydrostatic motorized spindle is studied by gas-solid coupling method, and the equivalent material characteristic of gas film is determined. On the basis of this, the dynamic characteristics of ultra-high speed air hydrostatic motor spindle are analyzed. The harmonic response analysis of modal characteristics is included. The results show that the axial stiffness of the motorized spindle increases obviously when the applied axial load increases, and the radial stiffness of the motorized spindle increases slowly when the applied radial external load increases. The three low order resonance frequencies of the spindle are in the range of the effective working speed of the motorized spindle. Near these three resonance frequencies the amplitude of the front end of the spindle is larger and the dynamic stiffness decreases rapidly. In order to verify the correctness of the simulation results of the dynamic and static characteristics of the ultra-high speed hydrostatic motorized spindle, the working speed of the spindle should avoid the resonance frequency as far as possible. Finally, the static stiffness test and idle operation experiment of the super-high speed aerostatic motorized spindle are carried out, and the theoretical analysis data are compared with the experimental test data, and the causes of the errors are analyzed at the same time.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH133.36

【引证文献】