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1、硕士学位论文五轴数控机床回转轴几何误差辨识及补偿 / 摘 要随着科学技术的飞速发展,人们的生活水平不断提高,社会对具有复杂空间曲面,以及高精度的机械零部件的需求越来越大。五轴数控机床已被广泛应用于具有复杂空间曲面的机械零部件的加工中。回转轴是五轴机床的重要组成部分,五轴机床切削工件时,能改变刀具的方向。由于五轴机床刚度较低且其加工精度没有三轴机床的加工精度高,提高五轴机床的加工精度就成了人们关注的重点。直线轴的几何误差已得到国外科研人员的广泛研究并取得了一定的成果,五轴机床回转轴几何误差的辨识及补偿方法是本文的主要研究容。本文首先讨论了回转轴静止误差的辨识及补偿方法。针对回转轴的静止误差,本文
2、设计了球杆仪的6种测量模式。在这6种测量模式中,一个回转轴转动,同时两个直线轴配合插补使球杆仪作圆运动。根据多体系统误差理论建立球杆仪读数的数学模型,推导单个误差元素在6种测量模式下对球杆仪读数的影响,并仿真分析这些误差元素对球杆仪读数的影响效果,然后将球杆仪运动轨迹的偏心与回转轴静止误差元素联系起来,辨识出回转轴静止误差,并给出了回转轴静止误差补偿的思路。接着,本文讨论了回转轴运动误差的辨识及补偿方法。针对回转轴的运动误差,设计了球杆仪的5种测量模式来检测回转轴的运动误差。在这5种测量模式检测的过程中,只有一个回转轴在转动,其余的轴都是静止的。这样球杆仪的读数就只包含了转动的那个回转轴的运动
3、误差而不受其他轴运动误差的影响。根据多体系统误差理论建立球杆仪读数的数学模型,并推导在5种测量模式下球杆仪读数的数学表达式,忽略其它误差因素的影响,如球杆仪的安装误差,联立5个数学表达式推导出回转轴运动误差的辨识公式,从而辨识出回转轴的运动误差,并给出了回转轴运动误差补偿的思路。回转轴几何误差的辨识及误差补偿是提高五轴机床加工精度的关键。因此,本文所讨论的回转轴几何误差的辨识及补偿方法是对五轴机床回转轴进行实际的几何误差补偿以提高五轴机床加工精度的基础和必要的前期工作,有着很强的实用性。关 键 词：五轴数控机床；回转轴；几何误差；误差辨识；误差补偿论文类型：应用基础本研究得到国家科技重大专项高
4、速精密数控机床动态综合误差补偿技术编号：I2009ZX04014-023的资助ABSTRACTWith the rapid development of science technology, peoples living standards are improving unceasingly and the community need more and more mechanical parts with complex space curved surface and high precision, such as blade and propeller in the large rot
5、ating machinery. Five axes nc machine tools have already been widely used to machine the mechanical parts with complex space curved surface. Rotary table is an important part of five axis machine tool. With low rigidity, the machining accuracy of five axis machine tool is lower than that of three ax
6、is machine tool, then to improving the machining accuracy of five axis machine tool becomes the keystone of the scientistsresearch. Because the geometric error compensation of three axis machine tool has been studied by the scientists at home and abroad, the geometric error identification and compen
7、sation of the rotary table in five axis machine tool are the main contents in this paper. The geometric error of rotary table has two groups. One is the link error, another is motion error.Firstly, this paper discusses the method to identify and compensate link error elements of rotary table. Consid
8、ering the link error of rotary table, this paper design six tests of ball bar to detect the link error. In these six tests, one rotary table is rotating, and another two linear axes is moving to make the ball bar do circle motion. According to the multi-body system error theory, this paper establish
9、es mathematical model of readings of ball bar in the six tests, analysises influence of single error element on the ball bar readings and simulate the influence through matlab software. Then relate eccentricity of ball bar trajectory with geometric error elements of rotary table to identify the geom
10、entric error elements. This paper also gives the method to compensate the link error of rotary table.Secondly, this paper discusses the method to identify and compensate motion error elements of rotary table. Considering the motion error of rotary table, this paper design five tests of ball bar to d
11、etect the motion error. In these five tests, only one rotary table is rotating, the rest axes is not moving in order not to introduce motion errors of other axes. Thus, ball bar readings only reflect motion errors of rotary table that is rotating. According to the multi-body system error theory, thi
12、s paper establishes the mathematical model of ball bar readings in the five tests designed and derives five equation of ball bar readings under the influence of motion error neglecting the other error elements such as the setup errors of ball bar to calculate the five motion error elements of rotary
13、 table. This paper also gives the method to compensate motion error of rotary table.The identification and compensation of geometric error of rotary table is key step to improve the machining accuracy of five axes machine tool. Thus, the contents of this paper is the basis and necessary preparatory
14、work of implementing geometric error compensation in five axes machine tools and this paper has strong practicality.KEY WORDS: Five axes machine tool; Rotary table; Geometric error;Error identification;Error compensationTYPE OF THESIS: Application Fundamentals目 录1 绪论11.1 研究背景及意义11.2 国外研究现状11.2.1 回转轴
15、静止误差的研究现状11.2.2 回转轴运动误差的研究现状21.2.3 几何误差补偿的研究现状31.3 论文研究容及主要章节安排51.3.1 论文研究容51.3.2 论文章节安排52 多体系统误差理论72.1 多体系统理论概述72.1.1 多体系统72.1.2 多体系统理论72.2 多体系统的描述方法82.2.1 多体系统的拓扑结构82.2.2 相邻体之间的几何描述92.2.3 齐次矩阵102.3 理想运动的齐次变换矩阵102.3.1 理想平移运动的变换矩阵102.3.2 理想旋转运动的变换矩阵112.4 实际运动的齐次坐标变换122.5 本章小结143 五轴机床回转轴的几何误差分析153.1
16、回转轴几何误差分类153.2 回转轴的静止误差153.3 回转轴的运动误差163.4 回转轴几何误差辨识及补偿思路173.5 本章小结174 回转轴静止误差的辨识及补偿184.1 静止误差的测量仪器184.1.1 球杆仪的结构184.1.2 球杆仪的测量原理184.2 静止误差的测量方法194.3 球杆仪读数的数学模型的建立214.3.1 主轴端小球的坐标214.3.2 工作台端小球的坐标234.4 误差对球杆仪读数的影响264.4.1 B轴转动的情形264.4.2 C轴转动的情形304.5 仿真误差对球杆仪读数的影响354.6 静止误差的辨识364.6.1 辨识步骤364.6.2 辨识方法374.7 静止误差补偿思路45
