三坐标测量机X向位置偏差的测量不确定度

提出了对三坐标测量机X向位置偏差δx(x)测量不确定度评定的一种模式,测量仪器采用了双频激光干涉仪.在数学模型的建立过程中充分考虑了δx(x)的溯源性,数学模型主要反映了三坐标测量机X向温度偏离20℃对测量值的影响.在不确定度传播律中较好的解决了各不确定度来源项对合成标准不确定度的贡献途径问题.在结论中讨论了u(δxx)的量值传递问题并提出了减小u(δxx)的对策.     

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。     

坐标测量机测量端面距离的不确定度评定

以坐标测量机端面距离测量为例,全面分析测量全过程中影响测量结果不确定度的主要因素,建立坐标测量机测量端面距离的不确定度数学模型;利用蒙特卡罗数值模拟方法进行仿真,得到被测参数的测量不确定度,给出了完整的测量结果,提升了坐标测量机的应用价值。将蒙特卡罗模拟方法评定结果与测量不确定度表示指南给出方法评定的结果进行比较,可以看出应用蒙特卡罗模拟方法对于评定复杂模型测量不确定度更方便、高效。     

双频激光干涉三自由度微振动测量系统

为获取光学平台多自由度微振动信息,设计了一种基于平面镜双频激光干涉的三自由度动态微振动测量系统。该系统利用激光多普勒效应,采用三个测量轴获得测量反射镜的三点位移信息,计算出测量镜平动、扭转角、俯仰角信息,实时检测三自由度的微振动情况,从而为光学系统的微振动补偿控制提供基础。对微振动测量系统进行了不确定度分析,建立了不确定度模型,为进一步提高系统精度提供理论依据,也为系统在校准和计量领域的应用奠定基础。实验过程中,采用高精度地震计对待测平台进行同步测量,与系统平动测量结果进行对比,验证了系统的测量准确性。该系统的平动分辨率可达到5nm,扭转角分辨率为5.05μrad,俯仰角分辨率为4.69μrad,具有多自由度、非接触、高分辨、可溯源的优点。     

坐标测量机动态测量不确定度评定研究

目前人们对三坐标测量机动态测鼍小确定度仍采用静态测量理论来评定,与其实际使用情况不符,带来一定的评定误差.本文分析了触发模式下三坐标测量机测头的主要动态误差源,通过改变测量速度和逼近距离对测头(Renishaw MH20i)动态误差的影响进行了实验测试,采用Monte Carlo方法对三坐标测量机测头动态测量不确定度进行评定,与使州传统的测量小确定度A类和B类评定结果相比较,本方法不受直接测量量相关性的限制,受问题条件限制小,评定更符合实际情况.     

悬臂式测量机测量不确定度分析与验证

针对在某五轴数控机床加工现场有限空间限制下,复杂结构工件的原位在线测量问题,设计了一种悬臂式坐标测量机.根据不确定度评定准则,分析了影响测量机测量不确定度的因素,提出了从理论上估计所设计结构形式测量机测量不确定度的方法,并从机构运动误差、机构变形以及温度等方面对测量机的测量不确定度进行了估计.实验结果显示,测量机的测量误差均小于测量指标所要求的测量不确定度.     

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。     

测量不确定度评定在三坐标测量机中的应用

介绍了三坐标测量机的工作原理,并结合测量不确定度评定在测量工作中的应用,分析影响其测量结果的因素,并对测量结果的不确定度进行了评定。     

平行双关节坐标测量机的标定及不确定度评价

借鉴国外ScanMax测量机所具有的优势,研发了RRP结构(即两个转动和一个直线运动)的平行双关节坐标测量机,并研究了该仪器的误差模型、标定方法和不确定度评定方法。首先,根据平行双关节坐标测量机的机械结构建立了仪器的数学模型和误差模型。然后,基于全误差分析技术设计了仪器的标定方案并分别介绍了对重力和扭矩变形、平行度、臂长、零位等参数的标定。最后,根据国家坐标测量机校准规范,提出了通过评价测量重复性和长度测量精度的方法来评定测量不确定度。实验结果表明:在1 000mm×250mm(直径×高度)的测量范围内,平行双关节坐标测量机的测量不确定度可达到12μm(k=2)。得到的结果验证了平行双关节坐标测量技术及全误差分析技术的可行性,为非正交坐标测量机的标定探索了新的方法。     

三坐标测量机及配合使用的光学转台测量结果不确定度的评估

本文着重介绍了采用量块、双频激光干涉仪和多面棱体、光电自准直仪对三坐标测量机及配套光学转台在校准过程中因各项标准设备引入的不确定度分量的分析和评定。通过对校准过程中标准器的选用和分析计算,证实了标准器在该类设备日常校准中的可行性和可靠性,也确保了实验室校准能力工作的开展。     

CMM uncertainty analysis with factorial design

The purpose of this research is to present a method to estimate the Coordinate Measuring Machine (CMM) measurement uncertainty. The approach is based on a performance test using a ball bar gauge and a factorial design technique. A factorial design was applied to carry out a performance test and to investigate CMM errors associated to orientation and length in the work volume. The CMM measurement uncertainty was estimated with components of variance obtained after statistical analysis of variance applied to volumetric measurement errors. An application was performed with a Moving Bridge CMM and the results were compared to the volumetric performance test proposed by ANSI/ASME B89.4.1 standard. The results showed that the proposed method is suitable to investigate CMM hardware performance and determine the contribution of machine variables to measurement uncertainty.     

Measurement uncertainty evaluation of conicity error inspected on CMM

The cone is widely used in mechanical design for rotation, centering and fixing. Whether the conicity error can be measured and evaluated accurately will directly influence its assembly accuracy and working performance. According to the new generation geometrical product specification(GPS), the error and its measurement uncertainty should be evaluated together. The mathematical model of the minimum zone conicity error is established and an improved immune evolutionary algorithm(IIEA) is proposed to search for the conicity error. In the IIEA, initial antibodies are firstly generated by using quasi-random sequences and two kinds of affinities are calculated. Then, each antibody clone is generated and they are self-adaptively mutated so as to maintain diversity. Similar antibody is suppressed and new random antibody is generated. Because the mathematical model of conicity error is strongly nonlinear and the input quantities are not independent, it is difficult to use Guide to the expression of uncertainty in the measurement(GUM) method to evaluate measurement uncertainty. Adaptive Monte Carlo method(AMCM) is proposed to estimate measurement uncertainty in which the number of Monte Carlo trials is selected adaptively and the quality of the numerical results is directly controlled. The cone parts was machined on lathe CK6140 and measured on Miracle NC 454 Coordinate Measuring Machine(CMM). The experiment results confirm that the proposed method not only can search for the approximate solution of the minimum zone conicity error(MZCE) rapidly and precisely, but also can evaluate measurement uncertainty and give control variables with an expected numerical tolerance. The conicity errors computed by the proposed method are 20%-40% less than those computed by NC454 CMM software and the evaluation accuracy improves significantly.     

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.     

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.     

Calibrating the volumetric errors of a precision machine by a laser tracker system

In this paper, a quick solution for measuring the volumetric errors of a precision machine is presented. It requires a laser tracker system and a plate including three caves on it. The laser tracker system can detect the coordinate of a sensor ball anywhere in the working space. The plate is fixed on the machine spindle. After installation, the spindle is moved toward the diagonal of the working space. The real movements are along the x, y, and z-axis directions, respectively; it will back to the diagonal line for one complete cycle motion. In each step movement, the spindle is stopped and the laser tracker detects the coordinates of the three caves by putting the target sensor ball into caves sequentially. By means of the coordinates, the volumetric errors at that position can be derived. The overall volumetric errors can be measured quickly by just one setup and many step movements with laser tracker detections.     

基于CAD的三坐标测量机检测规划系统的开发

为了提高检测自动化和智能化水平,提出基于CAD平台的三坐标测量机检测规划系统的开发方法.系统结构由外至里分为界面层、功能层、服务层和数据层四层,外层的操作和功能通过里层的支撑服务和数据实现.关键技术中检测几何信息的提取分为直接获取和元素离散点拟合两种方式;采样规划采用以规则分布为基础的步长自适应再分策略;路径规划主要涉及表面求交线的碰撞检查及基于启发式规则的碰撞规避;自动编程根据功能和规划信息依DMIS格式实现.整套系统基于三维CAD平台Open CASCADE进行了实现,相关实例表明该系统能很好地完成常见零件的自动检测规划任务.     

Design and analysis of experiments in CMM measurement uncertainty study

In applying a coordinate measuring machine to measure a mechanical object, many factors affect the measurement uncertainty. Although a number of studies have been reported in evaluating measurement uncertainty, few have applied the factorial design of experiments (DOE) to examine the measurement uncertainty, as defined in the ISO Guide to the Expression of Uncertainty in Measurement (GUM). This research applies the DOE approach to investigate the impact of the factors and their interactions on the uncertainty while following the fundamental rules of the GUM. The measurement uncertainty of the location of a hole measured by a coordinate measuring machine is used to demonstrate our methodology.     

基于激光的裙装自动裁边系统设计

为了实现丝绸裙装下摆修边和裁剪工序的自动化,提出了一种利用激光自动裁边的新方法。采用具有丰富外设资源的嵌入式微处理器LM3S615,完成了裙装立体裁边系统控制器的硬件设计,配合软件设计,实现了利用激光器自动裁边精确度更高、效率更高的目标。样机实验结果表明,该激光自动裁边系统具有良好的工作性能。     

CMM离线编程原型系统开发

为了发挥CMM(Coordination Measuring Machine)设备能力,降低测量成本,本文提出了一种基于离线环境下的DMIS(Dimension Measuring Interface System)测量路径自动生成的方法.它通过对三维CAD B-rep模型数据的分析和模型遍历,提取测量元素和有关数据;根据规则建立测量顺序,通过人机交互确认,最后对测头移动路径自动规划,生成无碰撞测量程序.本文简要介绍了离线测量程序自动生成原型系统的开发方法,系统在实际CMM设备上,对原型系统生成的DMIS程序进行了验证.