三坐标测量机测头系统动态特性研究

为了实现三坐标测量机的最佳动态测量精度,介绍了接触式测头的工作原理,研究了测头动态特性与测量机动态测量精度之间的复杂关系,提出了测头动态有效作用直径的概念。利用实验分析了测量机运动DCC参数对测头动态有效作用直径的影响,结果表明:测量机测头逼近距离对作用直径的影响远远大于触测速度和移动速度对作用直径的影响,而移动速度对作用直径的影响最小。     

三维螺纹测量机接触式测头的优化设计

为削弱接触式测头对高精度三维螺纹测量机精度的影响,设计了一种接触式测头结构尺寸优化方案,并提出了相应的标定方法。通过有限元仿真和正交试验优化测头结构参数,确定最优结构参数;利用坐标变换理论和最小二乘法原理建立测头标定模型并进行了标定试验;通过不同预压量下的螺纹塞规对比试验及螺纹环规、塞规对比试验对优化后的测头进行测试。结果表明：接触式测头测量螺纹塞规、环规参数标准偏差在1 μm左右,满足三维螺纹综合测量机接触式测头测量精度要求。该优化方案及标定方法为测头结构设计提供了重要的理论基础。     

基于虚拟再测量的精密转子轮廓测量技术

精密转子表面为典型的复杂螺旋曲面,采用三坐标测量机较难实现高精度的测量。对此,基于螺旋曲面的数字化特征模型及其等距面的相关几何性质,将转子轮廓的测量转化为导程参数和端面型线的测量,并提出一套新型的转子导程、型线等主要几何参数坐标测量方案。阐述转子数学模型及其测量数据处理的若干基本方法,在此基础上模拟三坐标测量机的步进采样测量过程,实现测量结果的不确定度评价和测量采样策略的优化选取。针对导程测量中存在的螺旋线特征点捕捉问题,提出了型线匹配测量法;为解决测尖半径补偿问题,提出基于虚拟再测量的补偿评价方法和不补偿直接评价方法。通过仿真和实际测量试验进行验证,其结果与转子厂家提供的理论数据吻合度较高,表明此方案合理。     

关节臂式坐标测量机角度传感器偏心参数辨识

对关节臂式坐标测量机中圆光栅角度传感器分度盘安装存在的偏心误差进行修正,可以有效提高测量机的测量精度。为了实现坐标测量机动态、实时的现场标校,建立了一种六自由度关节臂式坐标测量机的坐标系统,分析了圆光栅分度盘的安装偏心对角度测量的影响,推导了由于偏心引起的测量误差及其修正公式。分析表明,较小的安装偏心便会引起较大的角度测量偏差。以测量机的单点重复测量精度为目标函数,提出了一种基于模拟退火算法的角度传感器偏心参数辨识方法,并将其用于测量机关节圆光栅12个偏心参数的辨识和修正,实验结果表明,修正之后测量机的重复测量精度提高了11.3%。     

关节式坐标测量机热变形误差及修正

关节式坐标测量机工作温度范围宽,可以在线测量,应用领域越来越宽.这也使得其热变形误差随着对测量机测量精度要求的提高越来越受到关注,并且对其必须加以修正.简要分析关节式坐标测量机主要部件由于温度变化对测量的影响.关节式坐标测量机热变形误差模型用单隐层带反向传播前馈神经网络建立,网络的输入是测量机两个温度参数和测头的坐标值,输出为测头坐标相对于20℃该点的变化量.通过试验获得数据样本,训练所建模型并进行仿真.试验结果表明所建模型对关节式坐标测量机热变形误差修正是有效的.     

产品推荐

瓦尔特(无锡)有限公司HEVLICHECK高精度测量机Waller公司的Helicheck测量机,在当今多样的测量技术领域里铺设了一个全新的测量标准。带有4个NC轴和3个CCD照相机的测量机可以采用非接触式的测量方式,实现刀具一次装夹后对周齿、切削刃和端面的几何尺寸以及跳动等参数进行全自动测量。     

测量强反射自由曲面的测头设计

分析了利用三角法测量强反射表面时存在的问题。基于多目视觉测量 ,根据偏振特性 ,开发了由三个摄像机组成的测头系统。在建立几何模型的基础上 ,分析了各项结构参数对系统纵向分辨率的影响 ,对结构参数进行了优化 ,为实现自由曲面的高精度在线检测提供了理论依据。本系统与三坐标测量机相结合 ,能够测量金属强反射表面 ,具有高精度、高效率的特点。     

柔性关节式坐标测量机的误差源分析与建模

近30年来研究发展了可用于多种制造业的各种几何形体参数测量的柔性关节式坐标测量机,它具有灵活、轻便、价格较低等优点,适宜于现场使用,但限制其应用的关键就是其测量精度问题,本文首先建立测量机的测量模型,然后对影响测量机精度的误差源进行分析,建立更有效的误差模型。通过求出误差模型中各个参数并进行修正补偿后,大大提高测量机的精度,并分析了测量机存在最佳测量区域的问题。     

θFXZ型测量机的回转轴线标定方法

回转轴线的标定技术是保证θFXZ型测量机测量精度的一项关键技术。针对该型测量机没有y方向运动的特点,分析了其内外径测量原理,讨论了回转轴线标定误差与内外径测量误差的关系,并提出了一种基于环形标准件内孔、外圆的测量结果,快速标定回转轴线的方法。试验结果表明:利用该方法进行θFXZ型测量机的回转轴线标定,标定后,测量机对其它型号环形标准件的测量误差在±0.001 mm以内。该方法实现了对回转轴线的精确标定,同时操作简单,可以制定标定软件,实现回转轴线的软件自动标定。     

实现超长零件测量的三坐标测量机辅助设备研制及检测方法研究

针对特定三坐标测量机所存在的"测量范围受限,无法检测超过测量范围的超长零件"的问题,提出了一种基于测量基准重定位的超长零件测试方法,设计制造了一套基于三坐标测量机的超长零件辅助测量设备,制定了辅助设备和三坐标测量机相结合的超长零件检测方法。该方法利用精密几何体作为检测基准;采用移动超长零件、刚性变换测量数据和查错优化基准精度的理论,设计了相应测量软件;分析了测量精度影响因素,优化了测量方案。研究结果表明:在三坐标测量机和辅助设备相结合下,三坐标测量机长度测量范围由原来的750 mm扩展到了1 200 mm(拓宽了60%);超长零件的测量数据精度符合测量要求,实现了超长零件形位公差的精密测量。     

Error separation in CMM coordinate metrology

测量形状误差是精密制造业质量控制的关键部分。坐标测量机(CMM)是自动化精确测量维度尺寸和几何形状的机器。本文选用两种类型的坐标测量机触发探针进行标准工件测量,旨在研究不同的每转波数(UPR)时不可预见的动态固有误差的影响。整个实验过程使用探针类型和探针速度参数,采用快速傅立叶变换分析实验结果,得到受CMM机械结构和探针扫描速度影响而可预见的几何误差。实验结果表明,UPR的数量在进行圆形测量时对CMM准确度水平起非常重要的作用。本文对探针系统和坐标测量机结构响应的具体误差公式也进行了假设与分析,以经验数据来预测PRISMO-Bridge-CMM在NIS中的准确度。     

Precision tracking control of a horizontal arm coordinate measuring machine in the presence of dynamic flexibilities

One of the major sources that affect measurement accuracy and limit the use of high motion speeds in coordinate measuring machines (CMM) is the position error. In fact, static and dynamic probe errors are more direct factors in measuring machine accuracy, but are not the subject of this research. However the accuracy of acquisition of component position errors using a CMM in motion is also of importance, hence the dynamics of a CMM need to be considered. Therefore, this research aims to model the dynamics of a horizontal arm CMM by considering drive flexibility at joints and evaluates the characteristics of the system for fine motion control purposes. Design of a precision tracking controller (PTC) to perform superior tracking for enhancing the measurement accuracy and the probing speed in providing less inspection time at high motion speeds is carried out. A dynamic model for the CMM is developed including drive flexibilities represented with lumped springs at the joints. Due to the non-collocated nature of the control scheme in the flexible CMM dynamics, a non-minimum phase system is observed in the proposed CMM model. Using the derived CMM model with joint flexibilities, tracking motion control simulations are conducted at different probing speeds for the cases where a PI controller and a feedback PTC are employed. A comparison of the PI controller with the feedback PTC is also performed. Results demonstrate that the effects of joint flexibilities on the contour error and probing speeds are significant and the PI controller is not capable of providing good accuracy during challenging tasks such as corner tracking. However, the simulation results indicated that by using the proposed feedback precision tracking controller, contour errors in corner tracking that are caused by joint flexibilities can be reduced effectively .     

三坐标测量机非刚性误差的分析与补偿

根据移动桥式三坐标测量机非刚性效应测量误差的分布特征 ,通过对坐标测量机构件进行受力变形分析与建模 ,对坐标测量机的非刚性效应测量误差进行了分析 ,为高精度坐标测量机的误差补偿技术提供了新的思路     

Analysis of Natural Vibrations of Round Bimorph Piezoelectric Ceramic Plates of Arbitrary Dimensions. II. Rigidly Fixed Piezoelectric Plate

The problem of natural vibrations of a round bimorph rigidly fixed supported piezoelectric ceramic plate (piezoplate) of an arbitrary thickness with arbitrary axisymmetric electrodes is solved using the method of finite elements. The natural frequency spectra are analyzed in the resonance and antiresonance regimes. The displacement distributions over the piezoplate surfaces (vibration modes) are also analyzed and the dynamic electromechanical coupling coefficient (DCC) is investigated as a function of the relative plate thickness for various piezoelectric ceramic compositions. Round bimorph piezoplates with partial electrodes are considered; it is shown that the DCC can be significantly (by tens times) raised using partial electrodes. The results obtained make it possible to estimate the limits of applicability of the approximate one-dimensional theory and choose the optimum geometric dimensions of the plate and electrodes that ensure the maximum DCC.     

Enhance performance of inspection process on Coordinate Measuring Machine

Coordinate Measuring Machine (CMM) has been an important inspection tool in quality control for several years owing to its high accuracy and precision. Effectiveness of inspection plan generated by CMM greatly depends on measurement cycle time. Lesser the inspection time taken by CMM to measure a given part better will be the performance of inspection process. Therefore, it has been critical to reduce measurement time for efficient performance of inspection process. In this paper, methodologies to generate most suitable measurement path resulting into minimum inspection time has been introduced. These methodologies are based on different algorithms to reduce measurement cycle time for CMM. The different algorithms have successfully been explored and compared to show their effectiveness in minimizing inspection time for stationary CMM equipped with touch trigger probe. The proposed methodologies have also been implemented and tested on real-world mechanical part with certain number of features to demonstrate their applicability.     

Measuring large 3D structures using four portable tracking laser interferometers

A new concept that allows measuring 1D–3D objects in the range of several centimeters to 5 m × 5 m × 5 m is presented. In general terms the concept can be seen as a task specific correction of geometrical errors of coordinate measuring machines (CMMs). The developed system comprises a commercial CMM, its measurement and its evaluation software and a set of at least four high accurate tracking laser interferometers. The CMM is simply used as a mover which allows to capture points on the surface of a measuring object. In parallel the tracking laser interferometers follow a retro-reflector located close to the stylus tip of the tactile probe of the CMM. Based on a multi-lateration algorithm 3D-positions are calculated from the measured interferometric distances. Finally, two sets of coordinates emerged, namely, one by the CMM and the second from the metrological frame of the tracking laser interferometers. The interferometrically measured positions are usually more precise than the positions measured by the CMM. This is due to the high accuracy of the interferometric system and also due to the fact that the measurement positions are taken in a manner which almost avoids Abbe errors. Because of that, the measurement positions of the CMM are substituted with the more accurate measurement points calculated from distance measurements of the tracking interferometers. The position coordinates thus obtained are used for the further computerized evaluations, which yield the geometric parameters of the object measured. First measurements under laboratory condition show very promising results. It has been demonstrated that the concept is suitable for the high precision calibration of large workpieces with small tolerances, for instance, for the calibration of large gears for the windmill industry.     

陶瓷球轴承高精密电主轴临界转速分析

主要研究陶瓷球轴承高精密电主轴动态性能。首先简化并建立轴承—转子系统模型,然后根据电主轴高精度要求选择合适的预紧力,并计算出前后轴承的径向刚度;将所建模型导入软件,根据径向刚度值进行模态分析,结果可以看出所设计电主轴在实际运转中不会产生共振;最后分析出电机转子安装位置变化对临界转速的影响不大,并对比跨距和悬伸量两个模态参数对临界转速的影响,跨距影响最大,悬伸量次之,而安装位置影响最小。该研究为电主轴的设计提供良好的理论依据。     

Analysis of Natural Vibrations of Round Bimorph Piezoelectric Ceramic Plates of Arbitrary Dimensions. I. Simply Supported Piezoelectric Plate

The problem of natural vibrations of a round bimorph simply supported piezoelectric ceramic plate (piezoplate) of an arbitrary thickness with arbitrary axisymmetric electrodes is solved in the exact formulation using the method of finite elements. The natural frequency spectra are analyzed in the resonance and antiresonance regimes. The displacement distribution over the piezoplate surfaces (vibration modes) is also analyzed and the dynamic electromechanical coupling coefficient (DCC) is investigated as a function of the relative plate thickness for various piezoelectric ceramic compositions. Round bimorph piezoplates with partial electrodes have been also considered. The results obtained make it possible to estimate the limits of applicability of an approximate one-dimensional theory and choose the optimum geometric dimensions of the plate and electrodes that ensure the maximum DCC.     

一种基于固有频率分析的液压6自由度并联机构参数优化方法

液压6自由度并联机构存在固有频率低成本高体积大的缺点,在动态响应要求较高的场合使用常用的优化方法较难得到最佳性能,提出了基于固有频率的参数优化方法,建立了数学模型。考虑了液压系统主要运动部件活塞杆和油缸的摆动惯量,经过准确性验证后分析了液压缸面积、构件质量和结构尺寸等参数对系统固有频率的影响,实现了参数的优化。该优化方法简单、精确、高效,为固有频率较低的液压6自由度平台的参数优化及固有频率指标校核提供了新的理论研究手段,对实际工程具有指导意义。