虚拟装夹在轿车零部件三坐标测量中的应用

提出了一种虚拟装夹模式在三坐标测量工作中的应用方法.主要采用自行设计制造的柔性夹具的数模确定装夹方案,并通过对产品虚拟装夹所得出的数据结论,配合三坐标测量机,来确定夹具定位和夹紧的位置,最终完成对发动机罩盖的柔性装夹.     

三坐标测量辅助工夹具设计

介绍了目前三坐标测量柔性工件安装中存在的问题,有针对性地进行了三坐标测量辅助夹具功能分析,给出了一套工夹具（包括辅助测量工具）的设计方案。     

一种新型的柔性检测夹具

检测夹具是三坐标测量机使用过程中的主要辅助设备之一,尤其是对薄壁零件的测量,检测夹具更是一种必不可少的工具。一种新型的柔性检测夹具解决方案,无论是手动测量机还是自动测量机,该系统都具有极好的适应性。     

由机器人调整的可重构汽车车身焊接夹具的设计研究

介绍了一种全新的由机器人调整的可重构汽车车身焊接夹具,该夹具充分利用了焊装生产线上工业机器人的高精度与柔性自动化能力,并采用"一步直拉式"夹具定位调整方法,实现夹具的快速自动化构建与调整.     

三坐标测量机在自动化生产单元中的应用

本文主要研究了面向自动化生产单元在线测量技术,总控制系统与上下料机器人、测量机、数控机床和零点定位基座进行通信连接,基于零点定位系统实现测量基准与加工基准的统一,在总控制系统中,通过产品图号对零点定位托盘夹具、被加工零件的NC程序和三坐标测量CMM程序进行关联,建立一对一的对应关系;零件加工完成后,通过测量子坐标系进行零件自动测量,实现测量基准和设计基准的统一,从而实现了三坐标测量机在自动化生产单元中的典型应用,降低加工成本,提高生产效率,保证产品质量.     

基于Pro/M的组合夹具结构分析

组合夹具作为一种先进的柔性工艺装备,特别适用于数控机床、加工中心等先进制造单元,是今后夹具技术发展的一个重要方向。组合夹具由一整套标准元件组装而成,用有限元法计算其在切削力和夹紧力作用下的应力应变,以模拟夹具在实际加工过程中的变形,提高夹具设计水平。Pro/Mechanica是Pro/ENGINEER的一个有限元分析模块,可以实现与三维CAD软件Pro/E的无缝集成,能有效提高装配体有限元分析的效率。因此,基于Pro/Mechanica进行组合夹具结构分析,可及时发现设计缺陷,缩短夹具研制周期,提高效率。     

飞机翼面类部件数字化柔性装配工装设计及应用研究

对飞机翼面类部件的数字化柔性装配工装定位铆接技术进行了论述。通过分析传统刚性工装定位方法,明确在柔性装配中采用内定位的装配方式,以产品定位工艺孔为定位基准设计柔性工装,采用立柱式三坐标定位单元实现工装的柔性定位功能．利用工业机器人高度柔性化的结构特点,对翼面类部件铆钉孔进行制孔,结合DELMIA仿真反馈模型．确定柔性工装设计方案,使数字化柔性装配工装具有“夹具＋机床＋刀库”的自动化功能。     

航空叶片的三坐标自动测量技术

针对航空叶片三坐标自动测量技术研究现状,基于CAD数模的自动测量方法、自动定位夹具设计参考规则及先进自动测量系统特点三方面展开论述,并总结了航空叶片自动测量技术的未来发展趋势。结合检测效率低等问题,对比了4种解决方案,通过改进叶型检测流程,设计了一种燕尾型榫根叶片的自动测量夹具。     

汽轮机叶片三坐标测量的自动定位研究

使用三坐标测量机对汽轮机叶片进行检测时多数是以单件测量的方式进行,每次测量都需手动建立坐标系,增加了人机交互的环节,测量效率低下。设计开发了叶片测量专用夹具,通过实验验证,符合三坐标测量机的测量精度,为实现汽轮机叶片计算机集成测量自动化提供了解决方案。     

基于NX的柔性焊接夹具方案设计

针对动车构架组焊工序中采用的专用夹具适用性差的问题,对焊接夹具系统进行了分析。基于NX软件,采用模块化的方法设计了一种柔性焊接夹具。该夹具可满足多种型号铁路客车构架组焊定位夹紧要求,极大提高了设备利用率,同时提高了定位夹紧的准确性和可靠性。     

基于三坐标测量臂的大尺寸模板精度测量

本文重点研究工件尺寸大于其测量范围的零件测量方法,巧妙应用蛙跳算法实现了大尺寸凹凸模定位销、型腔孔柱定位尺寸及各型腔孔柱圆柱度、分形面的平面度等精度的综合测量。通过对凹凸模的测量结果进行形状和重合精度对比表明:凹凸模的定位销直径一致性较高,凹模的型腔孔直径较凸模柱的直径均匀,部分孔柱的重合精度较差,对中性最大偏差达到3.039mm。因此,需要改善该凸模的加工方法和夹具定位设计方案,提高其与凹模的重合精度。     

Measurement of form error of a probe tip ball for coordinate measuring machine (CMM) using a rotating reference sphere

This study presents a method of measurement of the form error of the tip ball in the tactile probing systems of a coordinate measuring machine (CMM) by using a rotating reference sphere. The measurement of the form error of the CMM probe tip was conducted without the use of additional external measuring instruments or sensors. The form errors of the probe tip ball and the reference sphere were separated from the probing coordinates of CMM by rotation of the reference sphere. The effectiveness of the proposed method was evaluated based on an uncertainty analysis. The uncertainty in measurement of diameter of the probe tip ball was estimated to be less than 0.5 μm.     

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.     

Verification of the positioning accuracy of industrial coordinate measuring machine using optical-comb pulsed interferometer with a rough metal ball target

An optical-comb pulsed interferometer was developed for the positioning measurements of the industrial coordinate measuring machine (CMM); a rough metal ball was used as the target of the single-mode optical fiber interferometer. The measurement system is connected through a single-mode fiber more than 100 m long. It is used to connect a laser source from the 10th floor of a building to the proposed measuring system inside a CMM room in the basement of the building. The repetition frequency of a general optical comb is transferred to 1 GHz by an optical fiber-type Fabry–Pérot etalon. Then, a compact absolute position-measuring system is realized for practical non-contact use with a high accuracy of measurement. The measurement uncertainty is approximately 0.6 μm with a confidence level of 95%.     

Calibration of an articulated CMM using stochastic approximations

A coordinate measuring machine (CMM) is meant to digitise the spatial locations of points and feed the resulting measurements to a CAD system for storing and processing. For reliable utilisation of a CMM, a calibration procedure is often undertaken to eliminate the inaccuracies which result from manufacturing, assembly and installation errors. In this paper, an Immersion digitizer coordinate measuring machine has been calibrated using an accurately manufactured master cuboid fixture. This CMM has been designed as an articulated manipulator to enhance its dexterity and versatility. As such, the calibration problem is tackled with the aid of a kinematic model similar to those employed for the analysis of serial robots. In addition, a stochastic-based optimisation technique is used to identify the parameters of the kinematic model in order for the accurate performance to be achieved. The experimental results demonstrate the effectiveness of this method, whereby the measuring accuracy has been improved considerably.     

三坐标精度测量机的工作原理和机械结构

开发了一种基于空间一维球列对称联系组合定标法的手提式三坐标精度测量机,其系统由球列板、滑轨、支架、底座以及伺服驱动系统、电气控制部分和数据处理软件组成。在准确已知球列上任意一对球心距偏差的条件下,可得到整个球列各球心距偏差,再以该球列各球心形成的标准点列与测量机空间的点列进行对称组合比较测量,按最小二乘原理处理测量值,可求得被测三坐标测量机被测空间点的误差,再按通用的数据分解方法即可得到坐标测量机几何结构的21项误差。利用全组合对称联系使一维球列校正精度达到高精度水平,同时由于球列可在该校正装置的滑轨上移动,使该装置可校正范围比球列本身的标准长度增加数倍。仅需在校正前对球板上的一个球心距进行检测标定并作为标准量,即可通过一次测量同时确定事先均未知的一维球列精度和三坐标测量机精度,使校正过程易于实现。此外,校正装置无需严格按国家标准量值传递定期校正,而可由使用单位利用已有标准量和简单装置在使用前进行实时检测标定,因此它对校正装置的长期稳定性无严格要求,可降低对校正装置的设计与制造要求。     

New method of testing of the repeatability of CMM articulating heads

A new method of testing of the accuracy of coordinate measuring machine (CMM) articulating heads was developed and verified. This procedure consists of the measurement of a test sphere, and requires only a basic configuration of the coordinate measuring machine. A new parameter describing the repeatability of angular positioning by CMM articulating probing system was defined.     

十回路自动旋转台的夹具设计

针对发动机零件的多品种柔性化共线生产和多回路自动旋转台在加工中心上应用的需求,提出一种柔性化、全自动的夹具设计方案。充分利用自动旋转台提供的10个回路(9(油/气)+1(水)),实现夹具的自动夹紧/松开和着座气动检测功能,同时采用模块化的两面快换板设计,提高夹具的柔性,满足多品种零件兼容和扩展的需要。快换板的定位和装夹采用了高精度的随行夹紧器和气密检测,提供了自动化快换功能。夹具的设计实现零件装夹和切换品种的两个全自动化,适应了当前工业智能化基本需求。     

FLEXIBLE ASSEMBLY FIXTURING LAYOUT MODELING AND OPTIMIZATION BASED ON GENETIC ALGORITHM

There are many welding fixture layout design problems of flexible parts in body-in-white assembly process, which directly cause body assemble variation. The fixture layout design quality is mainly influenced by the position and quantity of fixture locators and clamps. A general analysis model of flexible assembles deformation caused by fixture is set up based on "N-2-1" locating principle, in which the locator and clamper are treated as the same fixture layout elements. An analysis model for the flexible part deformation in fixturing is set up in order to obtain the optimization object function and constraints accordingly. The final fixture element layout could be obtained through global optimal research by using improved genetic algorithm, which effectively decreases fixture elements layout influence on flexible assembles deformation.     

A modular space frame for assessing the performance of co-ordinate measuring machines (CMMs)

In the present investigation, a new form of space frame for rapid verification of co-ordinate measuring machines (CMMs) is proposed and applied. This space frame has the form of a tetrahedron and is referred to as a modular space frame as different configurations of tetrahedron can be obtained easily and rapidly. The modular space frame comprises magnetic ball links and a ball plate. A typical magnetic ball link consists of two magnetic cups and a carbon fiber link, connecting magnetically, two high accuracy spheres. The volumetric error data obtained when a CMM measures the calibrated modular space frame can be used to verify whether a CMM maintains the manufacturer specifications. The experimental results have demonstrated that the modular space frame system has an acceptable repeatability and provides a practical and cost effective mechanical artifact to determine the volumetric accuracy of small/medium sized CMMs. The developed technique can be applied for calibration, verification, periodic reverification and acceptance test of any type of CMM.