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。     

Torque traceability examination of calibration laboratories in Korea

Torque is a physical quantity that is related to fastening bolt in various industry fields of assembling. The quality of assembling procedure is highly dependent on the accurate torque control. For the accurate torque measurement and control of torque, each torque transducer in industries should be calibrated using qualified torque calibration system. In Korea, there are 14 calibration laboratories for the torque measuring device. They have their own torque calibration system. Some of them are using deadweight torque calibration machine and the others have unsupported torque generating system using torque arm and masses.To check the reliability of the torque calibration laboratories, a series of round robin measurement was performed by the Korean National Measurement Institute, Korea Research Institute of Standards and Science (KRISS). This paper deals with the round robin measurement to check the traceability in torque in Korea. Two torque transfer standards each having 200 Nm capacity were used for the measurement. Measured value as well as the measured uncertainty of each laboratory was compared with those of KRISS.     

脉冲激光测距中信号处理系统嵌入式设计与实现

脉冲激光测距是一种技术先进、应用广泛的测距技术。介绍采用嵌入式设计实现基于脉冲激光测距原理的测量系统,着重论述了以可调节增益放大器和高速模数转换器为基础的电路设计,给出了硬件和软件的设计方法,实现了高精度时间间隔测量,并研制了专用的嵌入式检测仪器,具有良好的测距效果。该电路成本低、测量精度高,特别适合于大批量生产、低成本要求的应用。     

Integration of a laser interferometer and a CMM into a measurement system for measuring internal dimensions

In order to improve the existing comparative procedure for calibrating internal dimensions, we have developed a new measurement set-up for traceable absolute measurements. It consists of a co-ordinate measuring machine (CMM) and a laser interferometer (LI). The LI serves as a traceable measurement system, while the CMM is only used as a guiding system for the measuring probe. Extended research focused on defining probe parameters such as diameter, bending and indentation, as well as probing head repeatability and other error sources. The final goal of the research was to determine uncertainty of measurement under existing laboratory conditions. The main outcomes of the research and final uncertainty of measurement are presented in this article.     

风冷式粉碎机粉碎手机边框板刀具磨损试验研究

用表面形貌仪,采用平行试验方法,研究FL150型风冷式粉碎机粉碎手机边框板在常温和低温2种条件下,不锈钢304刀具、高速钢(W18Cr4V)刀具、Cr12刀具3种材料刀具的磨损情况。结果表明该粉碎机主要粉碎形式是“磨”,主要磨损形式是磨料磨损,3种材料中Cr12刀具抗磨效果最好;手机边框板经过低温预冷后,刀具磨损加大。     

引伸计与变形测量范围

从引伸计的结构、标距和测量范围、标称量程与输出灵敏度、示值的绝对误差和应变误差等几个方面论述电子万能试验机引伸计的正确配置。从材料力学性能测试所需的变形量、引伸计系统实际检定结果论述电子万能试验机有效变形测量的确定，从而指出了试验机行业内普遍存在的一个认识误区。     

一种新型机械零件表面形貌测量仪的研究

介绍了基于象散法的激光自动聚焦原理,论证了利用该原理在金属表面微位移测量技术中的应用,可通过对自动聚焦伺服系统各信号的控制来进行表面形貌的测量.研究并开发了一台基于已有光驱激光头及其伺服电路的经济型三坐标测量仪,使用步进电机带动丝杠传动实现X、Y轴的进给,通过改变步进电机驱动器细分数改变进给步长,读取聚焦良好时音圈电机的加载电压作为该点的Z坐标值.     

利用数字全息干涉术测量电路板的连续弯曲形变

采用离轴菲涅耳数字全息干涉术实现了对电路板表面的连续弯曲形变测量。在电路板两端依次施加0.01mm至15mm位移载荷过程中,记录了1 501幅全息图。通过相邻两幅全息图数值重建的复振幅相位分布相减得到干涉相位差,根据相位差与离面位移的关系计算得到照明测量区域的离面位移,通过累加获得了施加1～15mm位移载荷时电路板表面的弯曲形变测量结果。由5块相同规格电路板上照明测量区域中同一电容中心点的离面位移,计算得到测量结果的A类不确定度不超过0.008mm,加载夹具引起的测量结果的B类不确定度为0.003 5mm,测量结果的合成不确定度不超过0.008 7mm。实验表明这种利用离轴菲涅耳数字全息干涉术测量物体大位移连续弯曲形变的方法具有良好的重复性和稳定性。     

Modelling,kinematic parameter identification and sensitivity analysis of a Laser Tracker having the beam source in the rotating head

This paper presents a new kinematic model, a parameter identification procedure and a sensitivity analysis of a laser tracker having the beam source in the rotating head. This model obtains the kinematic parameters by the coordinate transformation between successive reference systems following the Denavit–Hartenberg method. One of the disadvantages of laser tracker systems is that the end-user cannot know when the laser tracker is working in a suitable way or when it needs an error correction. The ASME B89.4.19 Standard provides some ranging tests to evaluate the laser tracker performance but these tests take a lot of time and require specialized equipment. Another problem is that the end-user cannot apply the manufacturer’s model because he cannot measure physical errors. In this paper, first the laser tracker kinematic model has been developed and validated with a generator of synthetic measurements using different meshes with synthetic reflector coordinates and known error parameters. Second, the laser tracker has been calibrated with experimental data using the measurements obtained by a coordinate measuring machine as nominal values for different strategies, increasing considerably the laser tracker accuracy. Finally, a sensitivity analysis of the length measurement system tests is presented to recommend the more suitable positions to perform the calibration procedure.     

基于激光位移传感器的非接触三坐标测量机的设计

针对采用接触测头进行测量的三坐标测量机的测量效率低、不能对易变形物体进行测量等问题,设计了一种基于激光位移传感器的非接触三坐标测量系统,以PLC和工控机为主控,通过运动模组带动激光位移传感器定位,实现对工件表面特征点尺寸和数据的快速测量,且用户可通过触摸显示屏对设备进行操作.通过对待测工件进行实测表明,该设备能满足生产...     

一种激光挠测量系统的实现

本文介绍了一种用于大型土木工程结构的投影式光学挠度测量系统。系统由激光器、光接收器件及其外围信号采集处理电路组成。光接收部分采用特殊的光电接收器件取代传统的CCD或PSD,使测量范围得到扩大;外围电路部分采用现场可编程逻辑阵列FPGA器件作为核心。通过这种设计,系统的量程和可扩展性得到改善,实现了通道复用。实验室证明,系统的测量范围可以达到210mm,分辨率达到0.005mm,可完成结构的静态及动态挠度测量。     

基于机器视觉的激光线测量系统的构建与应用

简述了激光测量和机器视觉的基本原理,以此为基础构建了一台新型激光线测量机,介绍了该测量系统的硬件、软件和功能构成,并给出了测量实例。     

Laser tracker performance quantification for the measurement of involute profile and helix measurements

Standard-conforming measurements for a large involute gear were performed with a manually operated laser tracker system and the corresponding task-specific measurement uncertainties were estimated. Especially, readers using laser trackers for inspecting large involute gears will get information of a taskspecific measurement performance for the first time, which significantly differs from the laser tracker machine specification. To ensure unambiguous and repeatable measurement results, user-friendly auxiliary tools are used, which allows the operator to probe the measurement points according to existing guidelines and standards. Measurements were taken on a robust and highly accurate large involute gear measurement standard of the Physikalisch-Technische Bundesanstalt (PTB) under laboratory conditions. The size of this gear measurement standard complies with those gears used in wind power plants. The external gear materializes a left and a right hand gear as well as a spur gear. The obtained results of profile, helix and surface measurements are presented. These research activities were carried out at the PTB in the department of coordinate metrology.     

光盘伺服槽及预制格式刻划机计算机检测系统及机械传动链频谱分析

本文详细地论述了光盘刻槽机光电检测系统的设计、工作原理和检测系统的误差。设计了专用计算机接口板和有效的计算机软件程序。并对机械传动链作了理论分析和实际误差曲线的频谱分析。     

Assessing geometrical errors of multi-axis machines by three-dimensional length measurements

In this paper a method is presented for assessing geometrical errors of multi-axis machines based on volumetric three-dimensional length measurements. A universal machine error model is proposed since a large variety of machine configurations exists. Such models can be used for software error compensation techniques in order to improve the machine’s positioning behaviour as well as for diagnostic purposes. Length measurements are chosen for the measurement of the positioning errors of a multi-axis machine because these measurements can be executed in a short period of time in a relatively simple way combined with a high accuracy. In order to get comparable results for the geometrical errors as measured with conventional techniques, i.e., laser interferometry, the design of the measurement setup as well as the formulation of the machine error model (including parameter correlation effects) appeared to be of major importance and are subject of this paper.     

Ball array calibration on a coordinate measuring machine using a gage block

The distances between the balls of a ball array used in machine geometry calibration have to be very accurate. These distances can be calibrated using a laser measurement system, which requires specially designed optical devices and measuring probes. In this paper, a new and economical alternative method for calibrating the ball array is described. A single gage block is used for measuring the standard distance at the starting position. Then, the exact distances between the balls can be obtained by using the coordinate measuring machine (CMM) probe motion. This method does not depend on the accuracy of the CMM. Also, this method does not require expensive instruments or devices, but a CMM and a gage block. A simple “parallel-plane” bracket, mounted on to the measuring end of a CMM probe, is used to determine the centers of the balls automatically and accurately.     

Development of a measuring method for several types of programmed tool paths for NC machine tools using a laser displacement interferometer and a rotary encoder

Many circular motion measuring methods for NC machine tools have been proposed, however, the drawback common to many of these methods is the restriction on the radius size due to the short measuring range of the displacement transducers used. Moreover, most of these measurement tools are specialized, and can only perform circular test path measurements. A circularity test method using a laser displacement interferometer and a rotary encoder has been developed. The measuring method features a much longer range of motion than ordinal circular test methods such as the double ball bar (DBB) method and, therefore, the radius restriction on these measurements is greatly reduced. Moreover, this measuring system can also be used for the evaluation of positioning accuracy and other more complex test paths.

The proposed device consists primarily of a laser displacement interferometer and a rotary encoder. The holders for the interferometer head and the retroreflector are connected with a stainless steel rod. The retroreflector holder has a synthetic resin linear bearing allowing it to move relative to the interferometer head so that both optical components are always facing each other. The laser interferometer measures the change in distance between the interferometer head and the retroreflector, and the rotary encoder measures the rotation angle of the stainless steel rod.

In this paper, the background, measuring principle and apparatus structure are briefly described. The experimental setup is also presented. The apparatus was employed in several measuring experiments, including circularity tests for a vertical machining center. The results from these experiments support the validity of this measurement apparatus.     

Intermittent Process Measurement of a Freeform Surface Profile with a Circular Triangulation Laser Probe on a Machining Centre

This paper describes the development of a non-contact type system for measuring a freeform surface on a machine tool. A laser probe, model OTM-3A20 made by Wolf & Back Co., was integrated into a CNC machining centre as a non-contact sensor. An adjustment device for the laser probe was designed to minimise the cosine error caused by assembly inaccuracy. An alignment test of the measuring laser beam was carried out using a calibrated specimen. The systematic accuracy of the circular triangulation laser probe and a standard triangulation laser probe, with respect to the surface roughness, surface slope, and coating colour of the workpiece, was investigated by using an HP5529A laser interferometer system. The measuring system, which consists of a personal computer, a CNC controller of a machining centre, a Renishaw MP10 touch-trigger probe system, and the controller of the laser probe system, was integrated information-technically. Automatic measuring software was developed for the purpose of measuring path simulation, generation of NC codes, and error analysis of the measured data. The profile error of the tested object, measured by the laser probe and the coordinate measuring machine respectively was found to be within 45 μm. In this case, the tolerance of the designed part is about 50 μm, so the developed system can be applied to the inspection of mould production in bakelite according to the experimental results. ID="A1"Correspondance and offprint requests to: Dr Fang-Jung Shiou, Department of Mechanical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Rd. 106 Taipei, Taiwan. E-mail: shiou@mail.ntust.edu.tw     

Optimization of an algorithm for measurements of velocity vector components using a three-wire sensor

Hot-wire measurements of velocity vector components use a sensor with three orthogonal wires, taking advantage of an anisotropic effect of wire sensitivity. The sensor is connected to a three-channel anemometric circuit and a data acquisition and processing system. Velocity vector components are obtained from measurement signals, using a modified algorithm for measuring velocity vector components enabling the minimization of measurement errors described in this paper. The standard deviation of the relative error was significantly reduced in comparison with the classical algorithm.     

Methodology for teaching measuring systems

In this paper, a system approach to electrical measurement teaching is presented. This approach enables one to integrate different fields of measurements and different measurement courses. “Measuring Systems” is proposed as a main measurement course for students of Electronics Faculties. A multi-function laboratory stand for teaching measuring systems is proposed to train basic abilities in measuring system design. The stand consists of an IBM PC with an IEEE-488 (IEC-625) interface board, a bus tester, HP 33120A function generator, HP 34401A multimeter with IEEE-488 and RS-232 interface, and — optionally — a measurement plug-in card and a device with a VXI interface. Students are taught how to remote control, in a unifying way, various measuring devices with various interfaces, using simple IEEE-488 software and advanced software (LabWindows/CVI, HP VEE). The laboratory stand enables students to learn practical aspects of the design of measuring systems, teaching them the system approach to measurements.