大回转工件端面全跳动误差测量

对于回转工件,其端面跳动误差是指被测实际要素绕基准线作无轴向移动回转一周时,由固定的指示器测量工件端面在给定方向上最大与最小读数之差。被测点分布在端面的同一圆周上,对于大尺寸回转工件,只能借助加工该工件的机床进行在位测量。但由于机床主轴回转时常伴有轴向审动无法测出工件的真实窜动量。针对上述问题,我们设计、制作了旋转两测头端面全跳动测量装置,较有效地解决了大工件端面圆跳动误差的测量问题。一、旋转两测头法测量原理端面全跳动是指被测实际要素绕其基轴线作无轴向移动的连续多周回转,同时指示器作垂直于基准轴…     

重型卧式车床高精度主轴装配工艺研究

在主轴回转误差的基本概念中,主轴回转轴线的运动误差有径向圆跳动、端面圆跳动和倾角摆动三种基本形式。回转误差产生的原因有主轴（轴径圆度、同轴度、轴肩端面垂直度）、轴承（内圈精度、外圈精度、滚动体精度）、箱体轴承孔（轴承孔圆度、同轴度、端面垂直度）三种基本零件的误差。     

重型卧式车床高精度主轴装配工艺研究

1 概述 在主轴回转误差中,主轴回转轴线的运动误差有径向圆跳动、端面圆跳动和倾角摆动三种基本型式. 回转误差产生的原因有:主轴(轴径圆度、同轴度、轴肩端面垂直度)、轴承(内圈精度、外圈精度、滚动体精度)、箱体轴承孔(轴承孔圆度、同轴度、端面垂直度)三种基本零件的误差引起的.     

永磁同步型磨削电主轴运动精度分析

随着高档数控机床对主轴的运动精度的要求不断提高,研究永磁同步型磨削电主轴运行精度问题是十分必要的。在基于主轴振动误差和热分析的基础上,分别建立了径向误差运动、倾角误差运动和轴向误差运动数学模型。应用最小二乘法近似算法拟合主轴径向误差运动轨迹,然后对倾角运动误差进行建模,得到主轴回转轴线的倾斜角度。结合时域和频域信号分析方法,对轴向运动误差轨迹展开分析。为了实现一次测量主轴径向和轴向误差位移,并且获得主轴热误差,采用了典型的双标准球5-DOF测量主轴误差装置。通过国产某机床厂所研发永磁同步型磨削电主轴在试运行时主轴回转误差问题进行了实验。研究结果表明:当转速升高到最高转速,径向误差和轴向误差升高,离心力对主轴精度作用更加明显;当存在主轴偏心时,径向误差运动轨迹为逐渐由近似圆过渡到花瓣状态;双标准球五点法测试方法不仅可以判断电主轴制造存在的制造、装配等问题,并且该实验方法可应用于电主轴误差运动的实验,同时满足倾角误差、轴向误差运动和主轴温度变形的测试。     

减小主轴轴向跳动的措施

在一些精密机床中,如螺纹和齿轮加工机床等,其主轴、丝杠的轴向跳动对加工精度有很大影响,它将产生螺旋线误差。产生轴向跳动的主要因素是(以滑动轴承为例);主轴轴向承载面和箱体孔轴向承载端面对主轴回转中心线的垂直度误差所引起的,并使主轴发生弯曲变形所引起主轴偏摆。其次还有轴颈和轴承圆锥面加工误差。     

基于提高主轴回转精度的车床动力传动结构改进

主轴是机床的核心零件,机床主轴的精度和特性可以用来评价机床本身的精度。一般说来,主轴的回转精度是衡量一台数控机床技术参数的一个关键指标,它主要是指主轴前端和距离主轴前端一定长度的检测平面上安装工件或者刀具处的径向圆跳动量和端面圆跳动量,有时也会涉及到主轴倾角运动的变化量。回转精度通常是在无载荷的情况下,通过手动或者低速机动主轴进行测量的。     

第四讲 机床主轴部分精度的检验方法

几何精度检验中,主轴部分的精度主要包括:主轴回转精度──主轴回转中心线的径向跳动和主轴的轴向窜动;主轴上各工夹具定位面的精度──主轴锥孔中心线(或定心轴颈)的径向跳动和轴肩(或端面)的端面跳动;主轴 转中心线相对于机床其它部分的位置精度──如平行度、垂直度等。本讲仅介绍前面两个问题,主轴回转中心线相对于机床其它部分的位置精度在以后介绍。但所述检验方法,同样也适用于检验回转工作台的精度。 一、主轴回转精度　　　　1.概念　　　　图la是车床上加工外圆时的情况。实际上,工件除正常的回转运动θ(t)外,还会产生两个附加的…     

一种圆柱度测量基准的误差分离方法

通过对主轴回转误差运动的分析，结合三点法圆度误差分离技术，提出了一种完全分离圆柱度测量基准误差的分离方法，即利用主轴回转轴线平均线、测量传感器及直行导轨之间的空间位置关系，建立相应的坐标系，在分离出被测截面圆度误差、最小二乘圆心初始坐标的基础上，完整地分离出影响圆柱度精密测量的径向回转运动误差和导轨的直行运动误差。该技术不仅可以消除测量基准误差对圆柱度测量精度的影响，还可以实现主轴回转误差、导轨直线度以及导轨对主轴平行度误差的精密测量，对高精度误差补偿加工和机床的精度检验也具有重要意义。     

金属切削机床主轴运动误差影响的数学分析

在研究金属切削机床加工误差的基础上,针对机床主轴回转运动误差中的径向跳动误差、角度摆动误差和轴向窜动误差,以车床和镗床主轴为例,建立了主轴回转运动误差数学分析模型,从数学几何角度分别对上述主轴回运动城的加工精度影响结果进行了定量分析,并推导出了由此产生的各类加工几何误差不同的数学表达式。通过这些数学表达式可以定量地计算出机床主轴由于回转运动误差产生的加工几何误差数值。     

关于高精度车床主轴回转精度的测量

本文主要阐述了高精度车床主轴回转精度的几种测量方法。文中指出:对于超精加工机床、主轴回转精度的动态测试研究是直接提高另件加工精度的关键。介绍了国内外的动态测试的主要方法。文中还介绍了精密球加工机床主轴回转精度测量的方法。提出了采用试切另件后用电容测微仪对主轴径向与轴向进行近似测置的方法与理由。其测量结果和静态测量与加工另件精度基本相同。该方法适用于精加工及回转轴系具有良好的动平衡条件下的测量,测量装置简单易行,便于在生产现场使用.     

三点法中测头角位置的精密测量方法

研究了三点法圆度及轴系误差测量中测头角位置的精密测量方法。设计了能直接测量非接触电容传感器测头实测状态下的角位置的测角系统,提出了克服测头角位置测量误差及三个测头灵敏度标定误差影响的校正方法。实验表明：采用本文提出的“多刻线”法测角精度优于1′,测头角位置测量误差及三个测头灵敏度标定误差对测量精度的影响可降致最小。     

SURFACE PROPERTIES OF THE MACHINED WORKPIECE FOR HELICAL MILLS

Stability and surface errors are investigated numerically for milling operations with a helical tool. A detailed two degree of freedom mechanical model is derived that includes both surface regeneration and the helical teeth of the tool. The governing delay-differential equation is analyzed by the semi-discretization method. The surface errors are predicted based on the (stable) forced motion of the tool. New surface error parameters were introduced to characterize the properties of the spatial machined surface. The errors were calculated numerically for a given machine tool and workpiece for different axial depths of cut and spindle speeds. It is shown that both good surface properties and large material removal rate can be achieved by appropriate axial immersion in case of helical fluted tool. This phenomenon was proved analytically by means of the Fourier transformation of the cutting force.     

龙门数控机床主轴热误差及其改善措施

依据ISO和ASME标准建立龙门数控(Numerical control,NC)机床热误差测试条件,通过主轴恒转速和变转速热误差试验分析主轴箱温度场分布及其对主轴热误差的影响趋势。建立龙门机床误差元素模型,分析影响机床各坐标轴加工精度的主轴热误差分量。研究发现,主轴热误差和主轴箱温度存在单调对应关系,温度对主轴轴向的热伸长误差的影响要远大于主轴径向的热漂移误差,但温度变化相对各坐标变形存在热延迟和热惯性等特性。对主轴径向精度影响最大的热误差分量是由机床生热产生的同方向的偏移误差和与之垂直的偏转误差;对轴向精度影响最大的则是轴向的偏移误差。针对热误差特点和分布规律,提出结构优化、热平衡、误差补偿建模等3种减小热误差的措施,并对其各自优点进行了分析。     

三点法中测头最佳角位置的确定方法

论述了三点法圆度及轴系运动误差测量系统中确定三个测头最佳角位置的方法。通过分析测头读数误差对圆度各次谐波测量精度的影响,提出了确定三个测头最佳角位置的优化策略,基于MonteCarlo思想和单纯形模式搜索方法编制了高效、高精度的寻优程序,优化得到三个测头的最佳角位置。研究表明：在误差分析的基础上对三个测头的角位置进行优化能很好地解决三点法圆度测量形状失真问题,随机模式搜索寻优是确定测头最佳角位置的有效手段。     

Relationship between geometric errors of thrust plates and error motions of hydrostatic thrust bearings under quasi-static condition

A new model using approximate formulas is established to predict the error motions of hydrostatic thrust bearings. Three different types of geometric errors of thrust plates are listed in this paper including tilt errors, saddle shaped errors and petal shaped errors. The influences of them on lateral tilt error motion, longitudinal tilt error motion and axial error motion are discussed. Definitions of averaging coefficients are made based on the approximate formulas. It is found that the time-varying tilt errors are the main reason for the error motions of hydrostatic thrust bearings. The thrust bearings with six pairs of recesses have priority over the thrust bearings with four and three pairs of recesses in the view of rotation accuracy. Experiments are done using a hydrostatic rotary table with an outer diameter of 2 m. It is found that the second harmonic errors are the main component of the radial run-out and the results agree well with the results calculated from the approximate formulas.     

Spindle thermal drift measurement using the laser ball bar

Thermally induced errors are major contributors to the overall accuracy of machine tools. An important component of thermally induced errors is the error associated with spindle thermal drifts. In this paper, a novel method is developed to measure spindle thermal drifts in machine tools using a laser ball bar (LBB) as the calibration instrument. The method is implemented on a two-axis CNC turning center. The LBB is used to measure the coordinates of the spindle center and the direction cosines of the spindle axis at various thermal states. The axial, radial, and tilt thermal drifts of the spindle are then computed from the changes in these coordinates. The new method is verified by comparing the spindle drifts measured with the LBB to those measured by capacitance gauges. The results obtained by the new method show good agreement with the capacitance gauge technique. The primary advantage of the new method is the ability to measure the spatial coordinates of the spindle center and direction cosines of the spindle axis with the same instrument used for measurement of the geometric errors of the machine axes.     

Geometric error measurement and compensation for the rotary table of five-axis machine tool with double ballbar

This paper proposes a novel measuring method for geometric error identification of the rotary table on five-axis machine tools by using double ballbar (DBB) as the measuring instrument. This measuring method greatly simplifies the measurement setup, for only a DBB system and a height-adjustable fixture are needed to evaluate simultaneously five errors including one axial error, two radial errors, and two tilt errors caused by the rotary table. Two DBB-measuring paths are designed in different horizontal planes so as to decouple the linear and angular errors. The theoretical measuring patterns caused by different errors are simulated on the basis of the error model. Finally, the proposed method is applied to a vertical five-axis machining center for error measurement and compensation. The experimental results show that this measuring method is quite convenient and effective to identify geometric errors caused by the rotary table on five-axis machine tools.     

Investigation of error separation for three dimensional profile rotary measuring system

High precision 3D profile rotary measuring systems for large diameter workpieces are urgently needed in precision engineering. Error separation is critical for improving the accuracy of the system. In order to obtain higher accuracy for 3D profile rotary measuring systems, the random and systematic errors are analyzed and separated in this paper. In the measuring system, roll and pitch caused by the probe tilt violate the Abbe principle. Roll is removed by using two probes and pitch is separated by the interferometer method. The radial run-out and the perpendicularity error between the probe and the spindle axis are compensated by a two-probe-two-step method carried out on a standard hemisphere artifact. As the form error of the artifact is mixed with the perpendicularity error, the least-squares method is applied to fit the hemisphere and work out the perpendicularity error and the profile error of the hemisphere. Finally, numerical validation is presented using Matlab program to demonstrate the effectiveness and correctness of the proposed method.     

立式加工中心空间几何误差辨识解析及定位误差补偿研究

为大幅提升立式加工中心加工精度,满足当代数控机床对高精度的需求,针对立式加工中心3个运动轴,深入分析了其轴向运动空间几何误差,提出了可有效辨识运动轴轴向运动空间6项几何误差的辨识方法.建立了空间6项几何误差辨识模型,并针对关联轴联动垂直度误差进行了有效分析,建立了垂直度误差辨识解析模型.同时,针对3个独立运动轴轴向定位...