外文翻译数控机床几何误差及其补偿方法研究

1、毕业设计(论文)外文资料翻译系部： 机械工程系 专 业： 机械工程及自动化 姓 名： 学 号： 外文出处： cnc machine tool geometric error and its compensation method 附 件： 1.外文资料翻译译文；2.外文原文。 指导教师评语：此翻译文章详细描述了数控机床几何误差及其补偿方法研究，翻译用词基本准确，文笔也较为通顺，具备一定的英语基础，为在以后工作中接触英文资料打下了基础 签名： 年 月 日注：请将该封面与附件装订成册。附件1：外文资料翻译译文数控机床几何误差及其补偿方法研究摘要：对数控机床几何误差产生的原因作了比较详细的分析，将系

2、统误差的补偿方法进行了归纳，并在此基础上阐述了各类误差补偿方法的应用场合，为进一步实现机床精度的软升级打下基础。 关键词：数控机床；几何误差；误差补偿 前言 提高机床精度有两种方法。一种是通过提高零件设计、制造和装配的水平来消除可能的误差源，称为误差防止法 (error prevention)。该方法一方面主要受到加工母机精度的制约，另一方面零件质量的提高导致加工成本膨胀，致使该方法的使用受到一定限制。另一种叫误差补偿法(error compensation)，通常通过修改机床的加工指令，对机床进行误差补偿，达到理想的运动轨迹，实现机床精度的软升级。研究表明，几何误差和由温度引起的误差约占机床

3、总体误差的70%，其中几何误差相对稳定，易于进行误差补偿。对数控机床几何误差的补偿，可以提高整个机械工业的加工水平，对促进科学技术进步，提高我国国防能力，继而极大增强我国的综合国力都具有重大意义。 1几何误差产生的原因 普遍认为数控机床的几何误差由以下几方面原因引起： 1.1 机床的原始制造误差 是指由组成机床各部件工作表面的几何形状、表面质量、相互之间的位置误差所引起的机床运动误差，是数控机床几何误差产生的主要原因。 1.2 机床的控制系统误差 包括机床轴系的伺服误差（轮廓跟随误差），数控插补算法误差。 1.3 热变形误差 由于机床的内部热源和环境热扰动导致机床的结构热变形而产生的误差。 1

4、.4切削负荷造成工艺系统变形所导致的误差 包括机床、刀具、工件和夹具变形所导致的误差。这种误差又称为“让刀”，它造成加工零件的形状畸变，尤其当加工薄壁工件或使用细长刀具时，这一误差更为严重。 1.5 机床的振动误差 在切削加工时，数控机床由于工艺的柔性和工序的多变，其运行状态有更大的可能性落入不稳定区域，从而激起强烈的颤振。导致加工工件的表面质量恶化和几何形状误差。 1.6 检测系统的测试误差 包括以下几个方面： （1）由于测量传感器的制造误差及其在机床上的安装误差引起的测量传感器反馈系统本身的误差； （2）由于机床零件和机构误差以及在使用中的变形导致测量传感器出现的误差。 1.7 外界干扰误

5、差 由于环境和运行工况的变化所引起的随机误差。 1.8 其它误差 如编程和操作错误带来的误差。 上面的误差可按照误差的特点和性质，归为两大类：即系统误差和随机误差。 数控机床的系统误差是机床本身固有的误差，具有可重复性。数控机床的几何误差是其主要组成部分，也具有可重复性。利用该特性，可对其进行“离线测量”，可采用“离线检测开环补偿”的技术来加以修正和补偿，使其减小，达到机床精度强化的目的。 随机误差具有随机性，必须采用“在线检测闭环补偿”的方法来消除随机误差对机床加工精度的影响，该方法对测量仪器、测量环境要求严格，难于推广。 2几何误差补偿技术 针对误差的不同类型，实施误差补偿可分为两大类。随

6、机误差补偿要求“在线测量”，把误差检测装置直接安装在机床上，在机床工作的同时，实时地测出相应位置的误差值，用此误差值实时的对加工指令进行修正。随机误差补偿对机床的误差性质没有要求，能够同时对机床的随机误差和系统误差进行补偿。但需要一整套完整的高精度测量装置和其它相关的设备，成本太高，经济效益不好。文献4 进行了温度的在线测量和补偿，未能达到实际应用。系统误差补偿是用相应的仪器预先对机床进行检测，即通过“离线测量”得到机床工作空间指令位置的误差值，把它们作为机床坐标的函数。机床工作时，根据加工点的坐标，调出相应的误差值以进行修正。要求机床的稳定性要好，保证机床误差的确定性，以便于修正，经补偿后的

7、机床精度取决于机床的重复性和环境条件变化。数控机床在正常情况下，重复精度远高于其空间综合误差，故系统误差的补偿可有效的提高机床的精度，甚至可以提高机床的精度等级。迄今为止，国内外对系统误差的补偿方法有很多，可分为以下几种方法： 2.1单项误差合成补偿法 这种补偿方法是以误差合成公式为理论依据，首先通过直接测量法测得机床的各项单项原始误差值，由误差合成公式计算补偿点的误差分量，从而实现对机床的误差补偿。对三坐标测量机进行位置误差测量的当属利特, 运用三角几何关系,推导出了机床各坐标轴误差的表示方法,没有考虑转角的影响。较早进行误差补偿的应是何曼教授，针对型号moore 5-z(1)的三坐标测量机

8、，在16小时内，测量了工作空间内大量的点的误差，在此过程中考虑了温度的影响，并用最小二乘法对误差模型参数进行了辨识。由于机床运动的位置信号直接从激光干涉仪获得，考虑了角度和直线度误差的影响，获得比较满意的结果。1985年g. zhang成功的对三坐标测量机进行了误差补偿。测量了工作台平面度误差，除在工作台边缘数值稍大，其它不超过1m，验证了刚体假设的可靠性。使用激光干涉仪和水平仪测量得的21项误差，通过线性坐标变换进行误差合成，并实施了误差补偿。x-y平面上测量试验表明，补偿前,在所有测量点中误差值大于20m的点占20，在补偿后，不超过20的点的误差大于2m，证明精度提高了近10倍。 除了坐标

9、测量机的误差补偿以外，数控机床误差补偿的研究也取得了一定的成果。在1977年斯提克教授运用矢量图的方法，分析了机床各部件误差及其对几何精度的影响，奠定了机床几何误差进一步研究的基础。福劳瑞和其合作者也对该方法进行了研究，得出了机床几何误差的通用模型,对单项误差合成补偿法作出了贡献。金奈特更进一步将该方法运用于在线的误差补偿,获得了比较理想的结果。陈特建立了32项误差模型，其中多余的11项是有关温度和机床原点误差参数，对卧式加工中心的补偿试验表明，精度提高10倍。因斯劳特几乎使用了同张博士一样的测量方法，对三坐标铣床21项误差进行了测量，运用误差合成法得出了误差模型，补偿后的结果分别用激光干涉仪

10、和dbb系统进行了检验，证明机床精度得以提升。 2.2误差直接补偿法 这种方法要求精确地测出机床空间矢量误差，补偿精度要求越高，测量精度和测量的点数就要求越多，但要详尽地知道测量空间任意点的误差是不可能的，利用插值的方法求得补偿点的误差分量，进行误差修正，该种方法要求建立和补偿时一致的绝对测量坐标系。 1981年,在不同的载荷和温度条件下，对机床工作空间点的误差进行了测量,构成误差矢量矩阵,获得机床误差信息。将该误差矩阵存入计算机进行误差补偿。类似的研究主要通过测量机床工作空间内，标准参考件上多个点的相对误差，以第一个为基准点，然后换算成绝对坐标误差，通过插值的方法进行误差补偿，结果表明精度提

11、高了24倍。何曼则运用三维线性（lvtds）测量装置,得到机床空间27个点的误差（分辨率0.25m，重复精度1m），进行了类似的工作。进一步考虑到温度的影响，每间隔1.2小时测量一次，共测量8次，对误差补偿结果进行了有关温度系数的修。这种方法的不足之处是测量工作量大，存储数据多。目前，还没有完全合适的仪器，也限制了该方法的进一步运用和发展。 2.3相对误差分解、合成补偿法 大多数误差测量方法只是得到了相对的综合误差，据此可以从中分解得到机床的单项误差。进一步利用误差合成的办法，对机床误差补偿是可行的。目前，国内外对这方面的研究也取得一定进展。 2000年美国michigan大学jun ni教授

12、指导的博士生做了这样的尝试，运用球杆仪(tbb)对三轴数控机床不同温度下的几何误差进行了测量，建立了快速的温度预报和误差补偿模型，进行了误差补偿。christopher运用激光球杆仪（lbb），在30分钟内获得了机床的误差信息，建立了误差模型, 在9个月的时间间隔内,对误差补偿结果进行了5次评价,结果表明，通过软件误差补偿的方法可以提高机床的精度，并可保持精度在较长时间内不变。 误差合成法，要求测出机床各轴的各项原始误差，比较成熟的测量方法是激光干涉仪，测量精度高。用双频激光干涉仪进行误差测量，需时间长，对操作人员调试水平要求高。更主要的是对误差测量环境要求高，常用于三坐标测量机的检测，不适宜

13、生产现场操作。相对误差分解、合成补偿法，测量方法相对简单，一次测量可获得整个圆周的数据信息，同时可以满足机床精度的检测和机床评价。目前也有不少的误差分解的方法，由于机床情况各异，难以找到合适的通用数学模型进行误差分解，并且对测量结果影响相同的原始误差项不能进行分解，也难以推广应用。误差的直接补偿法，一般以标准件为对照获得空间矢量误差，进行直接补偿，少了中间环节，更接近机床的实用情况。但获得大量的信息量需要不同的标准件，难以实现，这样补偿精度就受到限制。 在国内，许多研究机构与高校近几年也进行了机床误差补偿方面的研究。1986北京机床研究所开展了机床热误差的补偿研究和坐标测量机的补偿研究。199

14、7年天津大学的李书和等进行了机床误差补偿的建模和热误差补偿的研究。1998年天津大学的刘又午等采用多体系统建立了机床的误差模型，给出了几何误差的22线、14线 、9线激光干涉仪测量方法，1999年他们还对数控机床的误差补偿进行了全面的研究，取得了可喜的成果。1998年上海交通大学的杨建国进行了车床热误差补偿的研究。1996到2000年在国家自然科学基金和国家863计划项目的支持下，华中科技大学开展了对数控机床几何误差补偿以及基于切削力在线辩识的智能自适应控制的研究,取得了一些成果。 综上所述：进行数控机床的误差补偿，误差测量是关键，误差模型是基础。通过误差的补偿，可以有效的提高机床的精度，为提

15、升我国附件2：外文原文cnc machine tool geometric error and its compensation method abstract: the geometric error of cnc machine tools were the cause of a more detailed analysis, the system error compensation methods were summed up, and on this basis on a variety of methods of error compensation applications, i

16、n order to further the achievement of precision machine tools lay the foundation for soft upgrade. keywords: cnc machine tools; geometric error; error compensationforeword improve the precision machine tool there are two ways. one is by improving the part design, manufacture and assembly level to el

17、iminate a possible source of error is called error prevention act (error prevention). this method is the main subject on the one hand, the precision machine tool processing constraints, on the other hand, lead to improving the quality of parts processing costs of expansion, with the result that the

18、use of this method are subject to certain restrictions. another called error compensation act (error compensation), usually by modifying the machines processing instructions for error compensation of machine tools, achieve the desired trajectory, precision machine tools to achieve a soft upgrade. st

19、udies have shown that the geometric error and the error caused by the temperature of the overall error of machine tool about 70 percent, of which the geometric error is relatively stable, easy to carry out error compensation. geometric error of cnc machine tools of compensation, you can raise the le

20、vel of processing machinery industry, the promotion of scientific and technological progress and improving chinas national defense capability, in turn greatly enhance chinas comprehensive national strength are of great significance.1 geometric error causes generally agreed that the geometric error o

21、f cnc machine tools from the following causes: 1.1 machine tool original manufacturing error machine refers to the composition of the various components work surface geometry, surface quality, the position error between the machine caused by errors in cnc machine tools is the main reason for the geo

22、metric error. 1.2 machine control system error including the machine tool axis servo error (follow the outline of error), cnc interpolation algorithm error. 1.3 thermal deformation as the machines internal heat source and environmental thermal disturbances resulting in the structure of machine tool

23、thermal distortion resulting from errors. 1.4-cutting process system load caused by the deformation caused by error including machine tools, cutting tools, workpiece and fixture deformation caused by error. this error also known as lets knife, which resulted in the shape of the processing parts dist

24、ortion, especially when processing or use of thin-walled workpiece slender tool, this error even more serious.1.5 machine vibration error in cutting, the cnc machine tools as a result of process flexibility and the ever-changing process, and its operation there is a greater possibility of falling in

25、to the hands of unstable region, which aroused strong flutter. resulting in workpiece surface quality and geometry of the deterioration of the error. 1.6 detection system test error include the following: (1) as a result of measurement sensors and its application in machine tool manufacturing error

26、on the installation of sensor error caused by the error feedback system itself; (2) as a result of machine tool parts and bodies, as well as in the use of error of deformation lead to sensor error. 1.7 outside interference error because of the environment and changes in operating conditions caused b

27、y random error. 1.8 other errors such as the programming and operation of an error caused by error.the above error may be in accordance with the characteristics and the nature of the error, into two broad categories: namely, system error and random error. cnc machine tools is the systematic errors i

28、nherent machine error, with repeatability. cnc machine tool geometric error is the main component of the also repeatability. use of the properties may be off-line measurement can be off-line detection - open-loop compensation technology to be amended and compensation to smaller, precision machine to

29、ols to achieve the purpose of strengthening.random error with a random, must be used on-line detection - the closed-loop compensation approach to the elimination of random errors on machining precision of the method of measuring instruments, measuring the strict environmental requirements and it wou

30、ld be difficult to promote.2 geometric error compensation technology for the different types of error, the implementation of error compensation can be divided into two broad categories. random error compensation request line measurement, the error detection devices installed in the machine directly,

31、 in the machine work, in real time to detect the location of the corresponding error, use this real-time error of processing instructions be amended. random error compensation of machine tool does not require the nature of the error can be at the same time machine random errors and systematic errors

32、 to compensate. however, the need for a complete set of high-precision measuring devices and other related equipment, the cost is too high, not cost-effective. 4 conducted online temperature measurement and compensation, failed to achieve practical application. error compensation system is the appro

33、priate machine tool equipment in advance of the test, that is, through off-line measurement to be the location of machine tool working space command error value, use them as a function of machine tool coordinates. machine work, according to the coordinates of processing points, out of the correspond

34、ing error to be amended. the stability requirements of machine tools is better, and ensure the certainty of machine errors in order to facilitate the amendment, the compensation depends on the accuracy of the machine tool repeatability and environmental conditions change. cnc machine tools under nor

35、mal circumstances, the repeat accuracy is much higher than its space integrated error, the error compensation system can effectively improve the accuracy of machine tools, and even can improve the accuracy of machine grading. so far, both at home and abroad on the system error compensation methods a

36、re many, can be divided into the following methods:2.1 synthesis of single error compensation method the compensation method is based on error of the theoretical basis for the synthetic formula, first of all through direct measurement machine measured the single original error by the error of synthe

37、tic formula for calculating compensation point error components in order to achieve the error compensation of machine tools. of coordinate measuring machine for measuring the location of error among leete, the use of triangular geometry, derived the coordinate axis machine error method, without cons

38、idering the impact of the corner. earlier error compensation should be hocken professors, for model moore 5-z (1) of the coordinate measuring machine in 16 hours, surveying the work space, a large number of points of error, in this process takes into account temperature , and least square method of

39、error model parameters identification. due to the location of machine signals directly from the laser interferometer to obtain, given the angle and straightness error of the impact was relatively satisfied with the results. g. zhang success in 1985 of a coordinate measuring machine error compensatio

40、n. worktable measured flatness error, with the exception of slightly larger numerical edge in the table, the other of not more than 1m, to verify the reliability of the rigid assumptions. the use of laser interferometer and measured the level of a 21 error, through the linear coordinate transformati

41、on error synthesis, and implementation of the error compensation. xy plane measurement tests showed that compensation for the former, in all measurement points in the error value is greater than 20m point accounted for 20%, in compensation, no more than 20% of the point of error is greater than 2m,

42、to prove the accuracy of nearly 10 times.apart from the coordinate measuring machine error compensation, the nc machine tool error compensation research has made some achievements. in 1977 professor schultschik vector method of analysis of the various components of error of machine tool and its impa

43、ct on the geometric precision of the effect of laying the machine tool geometric error basis for further study. ferreira and his collaborators have conducted a study of the method, the geometric error of machine tools come to a common model of a single error synthesis compensation act has contribute

44、d to. j. ni et al further the methods used in-line error compensation, access to a more satisfactory results. chen et al established a 32 error model, in which the extra 11 is about the temperature and machine error parameters of the origin of the horizontal machining center compensation tests showe

45、d that 10-fold improvement in accuracy. eung-suk lea et al almost used g. zhang with the same measurement method, to coordinate bridge port milling 21 errors were measured using the error synthesis error model obtained, the results of the compensated laser interferometer, respectively and renishaws

46、dbb system being tested and proved the accuracy of machine tools can be improved.2.2 error compensation act directly this approach requires accurate measurement of machine tool space vector error, compensation precision higher measuring accuracy and measuring the number of points required more detai

47、l but know that any point in space measurement error is not possible, the use of interpolation methods to seek compensation point of error components for error correction, the approach requires the establishment and compensation consistent absolute measurement coordinate system. in 1981, dufour and

48、groppetti in different load and temperature conditions, the working space of machine-point margin of error was measured, constitutes error vector matrix, was machine error message. the error matrix into a computer error compensation. there are similar studies acokafor et al, by measuring the machine

49、 working space, the standard reference piece on the multiple points of relative error to first for the reference point, and then converted into absolute coordinates error, through interpolation error compensation methods the results showed that precision can be improved by 2 4 times. hooman is the u

50、se of three-dimensional linear (lvtds) measuring device, the machine room for 27-point margin of error (resolution 0.25m, repeatability 1m), carried out similar work. further, taking into account the effects of temperature, each measuring 1.2 hours interval time, measuring a total of 8 times, the re

51、sults of error compensation of the temperature coefficient of repair. this inadequacy is a measure of heavy workload, store data and more. at present, has not been fully suitable apparatus, the method also limits the further application and development.2.3 relative error decomposition, synthetic com

52、pensation act most of error of measurement methods have been only a relatively comprehensive error, which can be machine decomposition single error. further use of synthetic methods of error of machine tool error compensation is feasible. at present, domestic and international research in this area

53、have also made some progress. michigan university of the united states in 2000, professor jun ni guidance chen guiquan doctoral made such attempt, the use of clubs miriam (tbb) of three-axis cnc machine tools at different temperatures were measured geometric error, the establishment of a rapid tempe

54、rature forecasts and error compensation model, carried out error compensation. christopher uses laser clubs miriam (lbb), in 30 minutes of the machine tool error information, the establishment of error model, in the 9-month time interval, the error compensation results were 5 times the evaluation re

55、sults show that through software error compensation method can improve the accuracy of machine tools, and to maintain the accuracy of the same for a long time. error synthesis requires the axis machine tools to detect the original error, more mature measurement method is laser interferometer, measur

56、ement and high accuracy. use dual-frequency laser interferometer measurement error, take a long time to debug the level of the operator requirements. more important is the measurement error of the high environmental requirements, commonly used in the coordinate measuring machine testing, not suitabl

57、e for the production operation at the scene. relative error decomposition, synthetic compensation act, a relatively simple measurement method, a measurement of access to the entire circumference of the data and information, at the same time meet the machine accuracy of testing and evaluation tools. at present, there are many error decomposition method, as it would vary from machine tools, it is difficult to find a suitable mathematical model of generic error decomposition, and the results of measuring the impact of the same