多步法体积定位测量与补偿的分析及应用

介绍了多步法体积定位测量，由于这种方法可以分离出各误差元素，所以可以方便而快速地检测出机床的体积定位精度。根据测量出的误差数据生成误差补偿代码，对其进行补偿以提高机床体积定位精度，并通过实例来验证该测量方法的正确性及高效率性。     

加工中心三维体积定位误差的理论及其激光测量

二十年前,机床最大的定位误差为丝杠的螺距误差及丝杠的热膨胀误差,但时至今日上述的大部分误差已被大幅度降低,因此机床的主要误差转而变成垂直度误差和直线度误差。所以,为了达到高的机床三维空间定位精度,机床上所有的3个位移误差、6个直线度误差和3个垂直度误差都得测量与补偿。目前,光动公司已为机床三维体积定位误差测量发明并研制了革命性的激光矢量测量技术(美国专利6,519,043,2/11/2003)。使用这种测量,仅需数个小时就可完成对机床误差的测量,而使用目前常规的激光干涉测量可能需要数日才能完成。因此,为了获得更高的加工精度,机床三维体积定位误差测量和补偿变得越来越紧迫和必要。本文首先介绍三维体积定位误差测量的基本理论及其公式推导,然后介绍LDDM硬件及其调整、数据采集和分析,最后给出基于激光矢量测量技术的体积斜线测量的结果。还要讨论这种新技术对三维体积定位精度、机床业的影响。     

三维空间定位精度定义与测量

20年前，大型机床的主要定位精度为丝杠的螺距误差及热膨胀误差，但直至今日上述的大部份误差已藉由线性编码器来减少与补偿，因此机床的误差转而变成以垂直度误差与直线度误差为主要原因，然而为了达到三维空间定位精度，垂直度误差与直线度误差的测量与补偿则变得更为重要。     

工件载荷对机床定位误差的影响分析及补偿研究

影响机床精度的因素众多，其中，工件载荷对机床产生的误差同样不可忽视。通过对机床的受载情况进行静力学分析，并利用激光干涉仪对机床的定位误差及其他各项几何误差进行测量，其结果显示，工件载荷对机床的几何误差存在很大影响，尤其在定位精度上，加载100 kg与空载相差10%左右，并且在进行误差补偿之后，这一差距会提升到40%左右，在此基础上提出了结合载荷的定位误差补偿方法。该方法解决了螺距误差补偿在实际工况下会产生欠补偿或过度补偿的问题。     

基于动态模糊神经网络的机床时变定位误差补偿

为提高数控机床的定位精度,提出基于动态模糊神经网络进行数控机床时变定位误差补偿的方法.针对数控机床定位误差影响因素复杂、模糊规则难于获取的情况,改进动态模糊神经网络,使其能够应用于多输入多输出系统,并实现模糊规则的自动在线辨识与生成.通过测量机床温度和定位精度,应用改进后的动态模糊神经网络建立机床时变定位误差预测模型....     

数控机床空间定位误差检测新方法研究

介绍了一种基于激光多普勒位移测量技术的机床几何误差测量辨识新方法,即激光矢量分步对角线测量法.该方法和传统的体对角线测量技术相比较,该方法能够取得3倍的数据,可以方便而快速地检测出机床的体积定位精度,并且能够获得足够的信息用于分离各误差元素,进而可以对其进行体积定位误差的补偿,大幅度提高了数控机床加工精度.     

数控机床体积定位精度的测量与补偿

介绍一种使用激光多普勒位移测量仪，对数控机床进行体积误差检测的激光矢量测量新方法，该方法可以方便而快速的检测出机床的体积定位精度，包括3个定位误差，6个直线度误差和3个垂直度误差，同时还可以根据测量的体积定位误差数据生成误差补偿的代码，进而可以对其进行体积定位误差的补偿，大幅度提高了数控机床加工精度。     

数控机床空间定位精度的测量与补偿

本文介绍一种使用美国光动公司的激光多谱勒位移测量仪，对数控机床进行空间误差检测的激光矢量测量新方法。该方法可以方便而快速地检测出机床的空间定位精度，包括3个定位误差、6个直线度误差和3个垂直度误差；同时还可以根据测量的空间定位误差数据生成误差补偿的代码，进而可以对其进行空间定位误差的补偿，大幅度提高了数控机床加工精度。     

切线法数控成形非球面机床的定位误差研究

分析了切线法数控成形非球面机床产生定位误差的原因,提出了一种改进型PID控制算法和开发型UMAC软件补偿并行的定位补偿方法,并给出了实现该方法的具体步骤。通过建立改进型PID控制模型和开发型UMAC误差修正表对该机床进行了定位误差补偿实验,结果表明该补偿方法可以有效地减小数控机床的定位误差,大幅度地提升数控机床的定位精度。     

数控弧齿锥齿轮磨齿机回转轴定位误差检测及补偿研究

基于回转轴激光多普勒测量原理,研究数控弧齿锥齿轮磨齿机回转轴定位误差检测和补偿。采用多普勒激光干涉仪MCV2002+RT—100转台对国产数控弧齿锥齿轮磨齿机YK2050回转轴定位误差进行检测,依据软件误差补偿原理,在机床数控系统Siemens840D中,通过修改数控系统的NC数据,对机床回转轴定位误差进行补偿,检测及补偿结果表明,回转误差补偿的方法和技术能极大的提高回转轴的定位精度。     

数控机床误差测量技术及其误差补偿

介绍了一种使用激光多普勒位移干涉仪对数控机床误差测量和误差补偿的方法。分轴步进体对角线测量法就是通过序列的单轴运动使机床沿着体对角线运动,这样便可以分离出数控机床的各项空间误差元素,包括直线定位误差、垂直直线度误差、水平直线度误差。然后利用测量误差自动生成补偿文件,输入数控系统,对误差进行相应的补偿。实验证明了这种测量和补偿的有效性。     

三维与三轴校准在机床生产中的差异

在机床的设计中，许多制造者都认为三轴和三维的精度是一样的。而实际上，三轴的精度只有一维，因为它只是用指定公差的线性来测量每个轴。三维的精度，是指线性测量每个轴与X，Y和Z轴的关系。标定三轴的精度是相当简单的，而标定三维的精度则较复杂．但能节省时间，所以，它是一个更好的方法。     

Dynamic and geometric error assessment of an XYC axis subset on five-axis high-speed machine tools using programmed end point constraint measurements

This paper presents a technique for assessing the volumetric errors on a five-axis machine tool for motion involving two linear axes and one rotary axis at selected feed rates using data from two sources. The first source of data is obtained through a programmed end point constraint procedure with measurement of the 3D volumetric positioning errors between a point on the tool holder and another fixed to the machine table reference frame. The tests involve maintaining the nominal coincidence of these two points whilst exercising the three axes. The second source of data is the position feedback signal from the encoder provided by the machine controller. Tests were carried out at low and high feed rates to evaluate the effect of geometric and dynamic errors. Polynomial functions are used to represent and then predict the geometric errors. The predicted geometric errors are then added to the dynamic errors provided by the servo errors from position feedback signals and propagated to the tool centre point and are compared with the measured volumetric errors. It shows that the influence of the geometric errors are dominant at low feed, whereas the effects of the servo errors of the linear axes become dominant as the feed increases, reaching 80% of the total error at a feed of 10,000 mm/min.     

数控机床误差的激光干涉仪自动瞄准测量及补偿技术研究

开发了用于数控机床空间误差测量的激光干涉仪自动瞄准系统。该系统实现了机床多轴联动、而激光束的方向发生连续改变时空间曲线轨迹定位误差的测量。提出了通过一次对光实现数控机床整个空间定位误差的直接测量方法。采用网格方法储存测量误差,用有限元法实现补偿误差的预报。在立式数控加工中心上进行了误差的测量和补偿试验,结果表明所提出的误差测量方法精度高、速度快,误差补偿效果明显。     

A Hole-Plate Artifact Design for the Volumetric Error Calibration of CMM

To measure the volumetric error of coordinate measuring machines (CMMs), a hole-plate artifact method was studied. Example designs of the hole-plate are shown using titanium and ceramic materials. The deflection by its own weight of the designed hole-plate is analysed using the finite element method. The hole distances moved by the deflection are shown in different hole-plate set-up cases, for vertical and horizontal positions. The influence of inside hole roundness as a measuring standard is also studied. Eccentric errors for different hole roundness are simulated. The hole-plate set-up errors are also discussed. A method for obtaining the parametric errors of a CMM is shown using the hole-plate as a measuring artifact for CMM positioning error. In addition, a method for measuring 2D and 3D length errors using the hole-plate data is introduced.     

Concept for the integration of geometric and servo dynamic errors for predicting volumetric errors in five-axis high-speed machine tools: an application on a XYC three-axis motion trajectory using programmed end point constraint measurements

A modelling approach for volumetric error prediction taking into account geometric and servo dynamic errors in a five-axis high-speed machine tool is proposed in this paper. Polynomial functions are used to represent and then predict the geometric errors. A simple second-order transfer function model is used to model and predict the servo dynamic error. The servo dynamic errors are added to the axis position geometric errors and propagated to the tool and workpiece using matrix transformations. The validity of the error integration concept is tested for a XYC three-axis motion trajectory. Two experimental setups are used. The first experimental test used the KGM grid encoder instrument to estimate the parameters of the servo dynamic error models of the X- and Y-axes. The second experimental test used a programmed end point constraint procedure with measurement of the 3D volumetric positioning errors between a point on the tool holder and another fixed to the machine table. The tests involve maintaining the nominal coincidence of these two points whilst exercising the three axes. These last tests are used to estimate the geometric error parameters and also to validate the prediction performance of the integrated geometric and dynamic model. The result shows the effectiveness of the error integration concept.     

Volumetric distortion assessment of a five-axis machine by probing a 3D reconfigurable uncalibrated master ball artefact

In this paper, a method is proposed that uses an artefact assembled in situ and exploiting the on-machine probing capability to perform a rapid volumetric distortion assessment of a five-axis machine. The 3D reconfigurable uncalibrated master ball artefact (RUMBA) is an assembly of the machine pallet and an adjustable number of master balls located within the machine working and probing envelop. The artefact design philosophy allows flexibility in the number and positions of the balls thus conferring the reconfigurability attribute. Reconfigurability allows adaptation of the artefact to the machine topology and geometry and its construction around a fixture and workpiece to reduce disruption to machine production. On the down side, the artefact is uncalibrated as its construction concept hinders precise knowledge of its geometry. During a test, combinations of all the machine axes are used to move and probe the master balls. A mathematical model is developed in order to identify the setup errors of each master ball and the probe. Simultaneous identification of the rotary axes’ linear offset with the setup errors is proposed to improve the parameter estimation and volumetric distortion prediction. The machine contribution to the volumetric distortion is then computed from the ball centre data excluding the setup errors. Tests are conducted in a laboratory on a horizontal machining centre. The results show that the proposed mathematical procedure is capable of removing the influence of the uncalibrated artefact geometry, excluding scale, and that the proposed design is suited to the machine environment.     

五轴数控机床万能主轴头空间误差建模研究

五轴机床万能主轴头空间误差建模的传统方法采用齐次变换矩阵(HTM)进行运算,计算过程复杂,物理意义很难理解。提出了一种主轴头空间误差的简化建模方法。综合考虑了主轴头两个旋转轴的运动误差和刀具热误差对主轴头空间精度造成的影响。优化了机床运动坐标系设置,从而降低了空间误差模型的复杂性。基于刚体运动学原理,描述了主轴头的运动误差传递关系。结合实例,推导出了主轴头空间误差的数学表达式,其建模过程简单,物理意义明确。