A New Algorithm for CAD-Directed CMM Dimensional Inspection

The recent developments in computer integrated manufacturing (CIM) systems have made the traditional dimensional inspections bottlenecks in the production line. To overcome these bottlenecks, computer integrated dimensional inspection was proposed with the coordinate measuring machine (CMM) being the key device. In this investigation, a framework for integrating manufacturing (CAD/CAM) environment is developed to automate the process of design, manufacturing and inspection. An algorithm to generate an optimum collision-free CMM probe path is proposed. This algorithm uses the ray tracing technique to locate the collision of the possible paths with the workpiece to be inspected, between the initial probe point and the target point. If there is a collision, the algorithm walks through the topological structure of the part and selects the midpoint of the edge shared by the face with which the path collides and the adjacent face nearest to the target point, as the next probe point. This procedure is followed until the target point is reached. The first half of the proposed algorithm is implemented using Mechanical Desktop as the CAD system and AutoCAD Runtime Extension (ARX) as the application programming interface, running on a Windows NT 4.0 platform. The effectiveness of the proposed algorithm is verified by the results of the implementation which demonstrate optimum collision-free dimensional inspection path generation for three prismatic parts.     

坐标测量机高精度测头技术

介绍了坐标测量机高精度测头的研究发展现状;分析了接触方式,光学方式,扫描方式测头的优缺点,研究了日本松下公司研制的高精度测头测量原理;基于原子力微探针的基本原理,设计了一种新型的坐标测量机测头,指出了采用原子力准接触技术是测头向高精度发展的方向之一。     

Standardised Reference Data Sets Generation for Coordinate Measuring Machine (CMM) Software Assessment

Rapid and accurate in-process measurement has recently become more common in product cycles, especially for producing parts having 3D contoured shapes. As a result, the ability to analyse large quantities of dimensional data requires today’s coordinate measuring machines (CMM) to employ their extreme functionality. With the increasing demand for performance of the software supplied for a CMM, the testing methods for these software packages must be rigorous, stable, and efficient. Motivated by the aforementioned demand, this work is intended to design and develop an algorithm and computer code to generate the reference data sets representing the coordinates of Gaussian associated features for CMM measured parts. These reference data sets can be used to test the CMM software submitted for approval to the National Institute of Standards and Technology (NIST). A generic algorithm for the development of the data sets is proposed and the program code is designed and developed by employing object oriented concepts. Dynamic errors during measurement are also accounted for, using Fourier harmonics representing the form errors and noise in the measured data. The data sets, being an integral part of the proposed International Standard – ISO 10360, will become a significant step towards the standardisation of software testing procedures for coordinate measuring machines.     

坐标测量机双频激光定标仪

分析了现有坐标测量机精度检具的局限性,提出了坐标测量机双频激光定标仪的设计方案,解决了在一次安装中以激光波长为长度基准检定坐标测量机单轴和空间示值精度的难题。     

Quality follow-up of CMM via the measurement of microdefects

The use of CMM in industrial environments requires a surveillance of their state of quality. The implementation of the procedure which allows to ensure the quality of the measurement is often left to the user’s initiative, which is powerless in the face of the complexity of the problem. We are interested in a new type of deviation that we call microdefects. We propose indicators which characterize the microdefects. These indicators are intended to point out metrological failure of CMM axes. We propose indicators that will assess the procedure adapted to a use of CMM in an industrial environment within an integrated CMM global survey system. After an introduction of the microdefects we are interested in, we describe the quality indicators we have defined and the procedure chosen to evaluate them. We conclude with the perspective for these indicators.     

三坐标机测量批量产品的快速装夹装置

针对三坐标机测量批量产品装夹效率低、产品装夹位置不固定的问题,设计了一套快速装夹装置,实现了批量产品的快速装夹测量。该装置装夹方便灵活,一致性好,大幅提高了测量效率,保证了快速测量时的精度。     

复杂曲面的三坐标测量机采样参数选取

为了提高复杂曲面零件测量精度,研究三坐标测量机若干采样参数对复杂曲面离散数据法向偏差的影响。文章以采样间隔和测量直径两组采样参数为研究对象,先通过理论分析两组采样参数对复杂曲面测量精度的影响,然后通过实验方法研究两组采样参数对复杂曲面法向偏差的影响,最后对实验数据进行统计分析,得到复杂曲面法向偏差图。研究结果表明:采样间隔和测球直径越小,曲面法向偏差越大,越能够反映曲面实际轮廓,提高了测量精度,保证了测量结果的准确性。     

应用于CMM的柔性定位夹具设计及应用

介绍了一种用于三坐标测量仪对球类工件进行定位的柔性夹具,既可独立使用,又可与现有三坐标组合式柔性夹具相互组合配套使用。在综合组合夹具优势的基础之上,设计了一种柔性定位夹具,可以实现球类零部件的有效支撑,同时可与组合夹具搭配,实现个多工位定位。该夹具结构简单,使用方便,具有广泛的使用范围。能有效保证定位可靠性,提高测量精度,提高仪器测量测量效率。     

测量造型中的CMM扫描技术

简要介绍了测量造型中应用的三维测量技术,并以实物模型为例重点介绍了基于三坐标测量机(CMM)的接触式扫描技术,认为接触式扫描技术在高精度测量应用中具有优势。     

面向任务的测量不确定度评估原理和方法

坐标测量机是典型的面向任务的测量设备,测量任务的改变将引入不同的测量不确定度。怎样评估坐标机面向任务的测量不确定度,目前我国还没有这方面专门的技术规范。参考ISO/TS15530系列标准,介绍了坐标测量机面向任务的不确定度评估原理和方法。     

Integration Planning Model of IDEF0 and STEP Product Data Representation Methods in a CMM Measuring System

The measuring process using a CMM involves a large amount of data. It is necessary to understand and clearly define the data required by the measuring process and the relationships of these data before incorporating automation into a CMM system. This paper uses the IDEF0 model to analyse the measuring function requirements for solving the problem of ambiguous internal information flow and material flow during the measuring process. A data module for the CMM measuring system was developed using the EXPRESS language in STEP, to support the IDEF0 function process module. An information flow design model was also established, which integrated the IDEF0 process requirement analysis model and the EXPRESS data module. The objective is to enhance the efficiency of the development of measuring systems by system designers, and to provide a basis for future development of measuring information systems using STEP data formats.     

Simple master artefact for CMM dynamic error identification

The proposition in this paper is a new method applying a simple master artefact for testing the dynamic performance of coordinate measuring machines (CMM). The principle of the method is presented and the method is used for identification and evaluation of dynamic error sources. The validity of the method is experimentally confirmed on a Zeiss ACCURA bridge coordinate measuring machine equipped with a Vast Gold active scanning probe, as well as Vast XXT passive scanning probe.     

Integrated laser/CMM system for the dimensional inspection of objects made of soft material

The applications of the coordinate measuring machines (CMMs) with a contact trigger probe to the dimensional inspection of manufactured products are restricted to the parts made of hard material, such as steel. By combining the laser and CMM, the applications of the CMMs can be extended to the inspection of objects made of soft materials, such as foils, plastics, wood, wax and clay materials. In this research, replacing the contact probe with an inexpensive laser sensor is attempted so as to eliminate the possible deflection of the component being measured when using contact probe. By combining a laser sensor with the existing automated inspection environment, a CAD-directed, three-dimensional coordinate sampling system which can perform non-contact dimensional inspection is developed.     

双螺杆压缩机转子齿形三坐标测量的半径补偿

双螺杆压缩机转子齿形进行三坐标测量机测量时,需要对球形测头半径进行半径补偿.结合转子螺旋曲面的几何特点,对转子型线测量数据点进行半径补偿计算,得到三坐标测量机球形测头真实接触点,再将空间分布的真实接触点旋转到相同横截面上得到转子型线数据点.通过实例验证该方法的有效性,可以应用于双螺杆压缩机转子型线的检测及逆向工程等工作中.     

Methodology of NURBS surface fitting based on off-line software compensation for errors of a CMM

Off-line software measuring accuracy enhancement has been suggested based on the prediction of the measuring error, . Based on the error lattice, a NURBS surface can be constructed and the normals of scatter compensated points can be calculated. Then based on the normals obtained and the probe radius, the final compensated points can be determined. Let the final compensated points be target points, the desired NURBS surface can be obtained by modifying the original NURBS surface constructed by let compensated points be control points.     

接触探测系统CMM验收检测和复检检测标准的探讨

在分析ISO/CD103605:2004以及GB/T16857.5(送审稿)的基础上,对具有接触探测系统CMM验收检测和复检检测标准中的术语和定义、计量特性要求、验收检测和复检检测、应用等若干问题进行了探讨,并提出了具体修改建议。     

汽车传动系故障诊断计算机辅助系统

本文采用正反向混合推理机制，深度优先的控制策略建立了一个基于知识的汽车传动系统故障计算机辅助系统，本系统包含二百多条规则，能自动诊断汽车传动系异响和功能变异两大类一百多种故障现象。     

A PC-based system integrating CMM and CAD for automated inspection and reverse engineering

A personal computer (PC)-based system integrating a manual CMM and a CAD system has been developed for on-line capture of 3D point data, resulting in the automation of the inspection process. The sequence of steps taken to measure a master component using the CMM is stored in a measurement program in teach mode and replayed for repetitive measurement of a batch of identical components in the replay mode. The measurement program guides the CMM operator regarding the geometric entity to be measured, the number of points to be input and the direction to be followed for taking the points on the CMM. The operator has simply to follow the sequence displayed on the computer screen. The program automatically computes the dimensions and the deviations from the corresponding dimensions of the master component. The 3D measurement data from the CMM are transferred to a CAD system in real time. Programs have been developed to create 3D cubic splines and surfaces from the 3D point data taken on the CMM. The full features of the CAD software can be used to manipulate the 3D point data for CAD applications.     

用三坐标测量机精确测量斜齿轮分度圆螺旋角

针对渐开线圆柱斜齿轮分度圆螺旋角的传统测量方法精度低、操作复杂等缺陷,提出用三坐标测量机精确测量圆柱斜齿轮分度圆螺旋角的方法,介绍了其测量原理及步骤,并进行了测量精度分析。理论分析和测量实践表明,该方法具有测量精度高、简便易行等优点。     

并联坐标测量机模糊PID控制系统研究

提出了一种自适应模糊PID的控制方法,并将其应用于液压驱动并联坐标测量机的控制。通过使用Matlab中的模糊工具箱,在Simulink环境下设计和搭建了模糊PID控制器,并以并联坐标测量机单通道的电液伺服系统为控制对象进行了仿真。