海德汉iTNC530数控系统在A/C轴双摆角铣头几何误差补偿中的应用

A/C轴双摆角铣头C轴轴线、A轴轴线与主轴轴线之间存在3个位置误差与3个角度误差,6个几何误差严重影响曲面零件的加工精度.通过百分表以及海德汉iTNC530数控系统可以补偿3个位置误差,而3个角度误差只能依靠提高零部件加工精度或采取若干调整措施才能予以解决.     

基于激光干涉仪的A/C轴双摆角铣头定位误差检测与辨识

A/C轴双摆角铣头是中、大规格五轴联动加工中心的关键功能部件.分析了A/C轴双摆角铣头的误差构成,包括两个定位误差、三个尺寸误差与三个角度误差,分析了三个尺寸误差与三个角度误差的检测手段与补偿方法,针对两个定位误差采用Renishaw激光干涉仪并配以RX10回转基准分度器的方法进行检测,介绍了Renishaw回转轴测量系统的工作原理,并详细说明了利用该系统进行A轴与C轴定位误差检测的方法.     

数控机床XY工作台单向运动二维阿贝误差分析与建模

为了提高数控机床的加工精度,建立误差补偿模型。对温度影响下的数控机床XY工作台导轨系统各误差分量之间的误差相关性进行研究。首先,分析了XY工作台单向运动时各平动误差和角度误差的相关性和X向导轨系统二维阿贝误差的变化规律。然后,建立了Y轴导轨系统和X轴导轨系统误差相关性的阿贝误差计算模型。最后,分别进行了X轴导轨和Y轴导轨角度误差的相关性验证和导轨系统定位误差补偿效果对比实验。实验结果表明:利用工作台二维阿贝误差补偿后的定位误差2整体误差呈减小趋势,且比用传统方法补偿后的定位误差1最大相差3μm左右,占补偿后的工作台总误差的三分之一。本文所建立的导轨系统二维阿贝误差模型更符合数控机床XY工作台误差的实际变化规律,利用该模型导轨进行的工作台联动定位误差补偿效果比传统补偿方法的修正效果更好,为实时补偿数控机床误差,提高机床加工精度和在机测量系统的测量精度打下理论基础。     

A/C轴双摆头几何精度误差的预防与补偿方案

通过A/C轴双摆头误差预防与误差补偿工艺方案的研究,设计了A/C轴双摆头装配工艺方案以及两轴回转中心的误差检测与补偿方案.将此研究方案应用于沈阳机床某A/C轴双摆头试制,效果良好.     

双轴转台分度误差检测与辨识技术

以自行研发的小规格五轴联动加工中心为例,分析了双轴转台的各项误差。简单介绍了Renishaw回转轴测量系统的构成、工作原理,并详细说明了利用该系统检测A轴与C轴分度误差的方法。利用该方法在我公司的五轴联动加工中心样机上对双轴转台进行分度误差检测,实践证明该方法具有检测精度高、检测重复性好、检测效率高等优点。     

五轴数控机床回转中心的几何误差检测与补偿

通过对转摆台式五轴数控机床回转中心几何误差的研究,提出了转摆台式五轴数控机床回转中心不重合几何误差的检测与补偿方法。将此方法应用于沈阳机床某转摆台式五轴数控机床,结合HEIDENHAIN ITNC530系统进行误差补偿,取得了良好效果。     

五轴头回转中心的几何误差检测与补偿

以SIEMENS大圆插补原理为基础,设计了五轴头回转中心不重合几何误差检测方法,详细解析了误差补偿原理及算法,并利用补偿值修正数控系统结构数据.将此方法应用于沈阳机床集团某型五轴加工中心的五轴头回转中心不重合几何误差检测与补偿,效果良好.     

工作台面对回转轴线垂直度的精密测试方式

为精确测量转台工作台面对回转轴线的垂直度误差,在转台上放置一个夹具,夹具能够相对于台面转动,再在夹具上放置电子水平仪。分别转动转台转轴和夹具体,读取两组电子水平仪读数。通过这两组读数进行谐波分析,解决了工作台面对回转轴线的垂直度测试的问题。     

双轴转台几何误差数学建模与解耦研究

通过雷尼绍激光干涉仪与RX10回转基准分度器对A轴与C轴的定位误差进行检测与补偿,使得几何误差总数由10项减少为6项,使得数学模型得到了极大简化.因此,最终可以通过几何误差数学模型求得各几何误差值.     

盘式离心机两回转轴线的平行度测试

在盘式离心机上建立了一系列坐标系，通过坐标系之间的姿态关系推导了工作基面坐标系相对于地理坐标系的姿态矩阵，在此基础上提出了将2维水平仪安装于工作基面上，分别旋转主轴与工作台轴，测试一系列数据，对这些数据进行谐波分析，得出了工作台轴线与主轴轴线的平行度，并分析了平行度误差对离心机静态半径测试的影响。     

车铣复合加工中心综合误差检测及补偿策略

根据五轴车铣复合加工中心的结构及其运动链构型特点,设计了综合误差检测方案。检测包括车主轴床身至铣主轴运动链的空间误差检测以及车主轴的热误差检测两部分。由于检测方案使刀具-工件之间构成了完整的运动链,解决了单纯的空间误差检测方法未考虑车主轴运动链误差影响的问题。文中同时提出了车铣复合加工中心综合误差补偿策略以及运用神经网络算法的几何误差和热误差综合补偿模型。采用分步体对角空间误差检测后,实施了空间误差补偿。补偿后四条体对角线的空间误差都明显减小,减小幅度从15.24 μm到50.83 μm,误差补偿效果从39.10%提高到78.06%。本文提出的方法极大地改善了空间误差补偿精度。     

Plane kinematic calibration method for industrial robot based on dynamic measurement of double ball bar

A new calibration method is proposed to improve the circular plane kinematic accuracy of industrial robot by using dynamic measurement of double ball bar (DBB). The kinematic model of robot is established by the MDH (Modified Denavit-Hartenberg) method. The error mapping relationship between the motion error of end-effector and the kinematic parameter error of each axis is calculated through the Jacobian iterative method. In order to identify the validity of the MDH parameter errors, distance errors and angle errors of each joint axis were simulated by three orders of magnitude respectively. After multiple iterations, the average value of kinematic error modulus of end-effector was reduced to nanometer range. Experiments were conducted on an industrial robot (EPSON C4 A901) in the working space of 180 mm × 490 mm. Due to the measuring radius of DBB, the working space was divided into 30 sub-planes to measure the roundness error before and after compensation. The average roundness error calibrated by the proposed method at multi-planes decreased about 21.4%, from 0.4637 mm to 0.3644 mm, while the standard deviation of roundness error was reduced from 0.0720 mm to 0.0656 mm. In addition, by comparing the results of positioning error measured by the laser interferometer before and after calibration, the range values of motion errors of end-effector were decreasing by 0.1033 mm and 0.0730 mm on the X and Y axes, respectively.     

Thermally induced volumetric error modeling based on thermal drift and its compensation in Z-axis

Traditional thermally induced volumetric error modeling requires 21 geometric error components at different temperatures. Taking thermal drift errors into account, 30 geometric errors are described to model volumetric error in this paper. The main sources of thermally induced volumetric error are positioning errors of each axis and thermal drift errors. An experiment on milling and boring machine is carried out, which shows that volumetric error in Z-axis is affected significantly. To compensate volumetric error of Z-axis, a model of positioning error is proposed based on nut temperature. A finite elements analysis of headstock thermal characteristic is carried out, and error chain is established, which shows the main source of thermal drift of Z-axis is ram expansion. Thermal drift compensation system of Z-axis is developed based on Invar metal and thermal error compensation module of Siemens CNC system. Therefore, the positioning error and thermal drift of Z-axis are compensated. The thermally induced volumetric error in Z-axis is reduced by 80 % after compensation.     

五轴数控机床工作台的几何误差测量

针对回转轴误差的定义,最终确立以基于最小二乘圆法,对回转工作台几何误差的测量方案.并以HS664RT五轴联动立式加工中心作为研究实例,完成数控回转工作台的几何误差测量实验.用Matlab建立了求解标准球安装误差的算法,并对回转工作台几何误差进行了辨识建模.     

五轴数控机床转动轴误差元素的球杆仪检测方法

提出一种立式高速精密五轴加工中心转动轴C轴误差元素的球杆仪检测方法。建立了影响加工精度较大的C轴4项误差的球杆仪检测模式。通过机床多轴联动使球杆仪完成一圆弧轨迹运动,此过程中,采集球杆仪的杆长变化量,由数学建模及轨迹仿真,结合误差敏感方向分析,最终分离得到各误差元素值。通过对比球杆仪检测误差值与预设误差值,证明球杆仪检测法是一种高效准确的转动轴误差检测方法。     

数控机床几何精度综合解析与试验研究

以对机床精度影响较大的几何误差为对象,通过理论与试验相结合,对其进行较深入的研究。基于多体系统理论,综合考虑各轴定位误差、直线度误差以及角度误差等几何误差元的耦合作用,提出一种机床综合误差建模方法,并在机床坐标系下建立三轴数控机床综合误差模型。通过利用激光干涉仪的大量试验得出定位误差、直线度误差以及角度误差曲线,分析证实定位误差相对于直线度误差和角度误差影响更为显著。以此为基础,进一步研究工作空间综合误差在各轴各误差元耦合作用下的分布和演变规律,发现综合误差在某轴向的分量与该轴的定位误差非常接近,给出定位误差是影响综合误差的决定性因素的结论。机床几何精度的分析对于机床精度补偿方法的选取与运用具有理论和实际意义。     

Influence of position-dependent geometric errors of rotary axes on a machining test of cone frustum by five-axis machine tools

A machining test of cone frustum, described in NAS (National Aerospace Standard) 979, is widely accepted by machine tool builders to evaluate the machining performance of five-axis machine tools. This paper discusses the influence of various error motions of rotary axes on a five-axis machine tool on the machining geometric accuracy of cone frustum machined by this test. Position-independent geometric errors, or location errors, associated with rotary axes, such as the squareness error of a rotary axis and a linear axis, can be seen as the most fundamental errors in five-axis kinematics. More complex errors, such as the deformation caused by the gravity, the pure radial error motion of a rotary axis, the angular positioning error of a rotary axis, can be modeled as position-dependent geometric errors of a rotary axis. This paper first describes a kinematic model of a five-axis machine tool under position-independent and position-dependent geometric errors associated with rotary axes. The influence of each error on machining geometric accuracy of a cone frustum is simulated by using this model. From these simulations, we show that some critical errors associated with a rotary axis impose no or negligibly small effect on the machining error. An experimental case study is presented to demonstrate the application of R-test to measure the enlargement of a periodic radial error motion of C-axis with B-axis rotation, which is shown by present numerical simulations to be among potentially critical error factors for cone frustum machining test.     

New method for computer numerical control machine tool calibration: Relay method

Relay measurement method, which uses the kilogram-meter (KGM) measurement system to identify volumetric errors on the planes of computer numerical control (CNC) machine tools, is verified through experimental tests. During the process, all position errors on the entire plane table are measured by the equipment, which is limited to a small field. All errors are obtained first by measuring the error of the basic position near the original point. On the basis of that positional error, the positional errors far away from the original point are measured. Using this analogy, the error information on the positional points on the entire plane can be obtained. The process outlined above is called the relay method. Test results indicate that the accuracy and repeatability are high, and the method can be used to calibrate geometric errors on the plane of CNC machine tools after backlash errors have been well compensated. __________ Translated from Journal Huazhong University of Science and Technology (Nature Science Edition), 2005, 33(11): 60–62 [译自: 华中科技大学学报(自然科学版)]     

Geometric error calibration of multi-axis machines using an auto-alignment laser interferometer

This work will report the development and application of an auto-alignment laser interferometer system for the geometric error calibration of CNC multi-axis machines. The system is capable of a diagonal displacement measurement, where multiple machine axes are moved simultaneously, with automatic optic alignment. This capability provides a solution for quick evaluation of the overall volumetric error of a multi-axis machine tool. One application of the system is that the 21 geometric errors of a 3-axis machine can be quickly estimated from the displacement measurements of some determined diagonal lines in the working volume. Compared with a time of several days using a conventional laser interferometer system, it takes only 1 hour for the proposed system to complete the geometry calibration of a 3-axis machine. A method for the roll calibration of a vertical axis is also proposed and demonstrated in this work.