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1.
This paper describes an industrial comparison of coordinate measuring machines (CMMs) carried out in the Scandinavian countries from October 1994 to May 1996. Fifty-nine industrial companies with a total of 62 CMMs participated in the project and measured a comparison package with five items chosen to represent a variety of dimensions, angles, and other geometrical quantities. A tool holder, two gauge blocks, a straightedge, and a ring together with instructions on how to measure the items were produced and sent to each participant. Simple measurement tasks were observed to be carried out with good results for the majority of the participants; whereas, increasing the level of difficulty from simple length measurements to more complex geometrical quantities gave severe problems for some of the companies. This occurred even though the participants measured according to prescribed procedures. An important part of the intercomparison was to test the ability of the participants to determine measurement uncertainties. One of the uncertainties was based upon a “best guess” but nevertheless, many participants did not even report this uncertainty. Uncertainty budgeting was not used for measurements other than simple length. For each company, a comparison of their measurement ability with the reference laboratory and other Scandinavian companies was made possible. A network regarding CMMs was created in these Scandinavian countries. 相似文献
2.
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. 相似文献
3.
This paper presents an optimised method for the characterization of circular features of any amplitude, which includes the capture of geometric data, by means of the use of three-coordinate measuring machine or digital optical machines with a CCD camera, and its subsequent mathematical processing. The proposed model determines the radius and the circularity error, based on the minimum zone method, and to this end it uses linear programming techniques, the Simplex programming principles and the limaçon approximation. An experimental study on ring gauges and reference disks is provided, including a comparative analysis using the Chauvenet and Grubbs filtering procedures. Last of all, an uncertainty estimation method is proposed by means of the Monte Carlo simulation. The experimental analysis carried out on ring gauges and reference disks accredit that the algorithm developed, implemented in a Matlab® environment, gives reliable results for any circumference arc considered, regardless of its amplitude. 相似文献
4.
Quasi-stiffness model is effective for the compensation of the geometric errors of coordinates measuring machines (CMMs) in slow probing, but degrade the error compensation accuracy due to the generation of dynamic errors in fast probing. It is usually regarded that acceleration is the major origin of dynamic errors; and yet the dynamic effects that rise from the quick fluctuation of geometric errors in fast probing had attracted little attentions. This paper presents a model for the dynamic effects of the geometric errors of CMMs in fast probing, and investigates their properties with experiments. The error model is built with recursive least squares (RLS) identification technique by taking probing acceleration and the 6 geometric errors of X slideway for the inputs while the positioning error of probe tip for output. Then the positioning error of probe tip is decomposed into 7 components corresponding to the 7 inputs. Analyses on the experiments show that the angular errors around Y and Z axes, εY(x) and εZ(x), can induce remarkable dynamic effects, especially in a CMM with low stiffness air bearing. Error compensation with RLS identification seems feasible theoretically, but it is not recommendable due to the veracity uncertainty of identification. Nevertheless smoothening the sharp corners of the curves of geometric errors, especially εY ∼ x and εZ ∼ x, in terms of probing speed and Y coordinates of probe tip is considered as a simple but effective and reliable method to improve the accuracy of CMMs errors compensation in fast probing. 相似文献
5.
任意方向上直线度误差的评定新方法 总被引:11,自引:1,他引:11
针对任意方向上直线度误差评定存在的非线性方程组求解困难、评定结果不精确、数据处理不能实现自动化等问题,提出将任意方向上直线度误差的评定问题,转化为给定平面内直线度误差与圆度误差的评定问题,推导数据处理方法与误差评定方法,并通过测量验证所提出方法的可行性。结果表明,所提出的方法不仅简单、易于计算机自动数据处理,而且评定精度比一般的方法提高约5%。 相似文献
6.
本文讨论了评定直线度误差的计算机精确算法,给出相应的程序框图,并介绍了程序的实现方法。通过在实验室和企业中的实际运用,证明了该方法的有效性和程序的可靠性。 相似文献
7.
F. L. Chen Y. M. Chiang 《The International Journal of Advanced Manufacturing Technology》1999,15(4):261-267
This study presents a novel mathematical method for resolving the accessibility of a through slot when using coordinate measuring
machines. The proposed method considers the actual shape of a probe consisting of a motor column, a stylus, and a probe tip.
Also derived herein is a mathematical method to derive the feasible probe orientation of the measurement point in the bottom
of a slot using a geometrical relationship between the probe and the slot. 相似文献
8.
Multiple orientation technique for the calibration of cylindrical workpieces on CMMs 总被引:1,自引:1,他引:1
Coordinate measuring machines (CMMs) are widely used in various fields of precision engineering and science. Although they are highly accurate instruments, for some tasks, e.g. calibration of reference artifacts, the accuracy even of the best available instruments is not sufficient.In this paper, we describe a highly accurate technique using a CMM for the measurement of cylindrical workpieces. The proposed method is a combination of multiple orientation and substitution techniques and compensates for all geometrical errors of a CMM, systematic probing effects and the bending of the workpiece due to gravity. We demonstrate the method on a cylinder gauge with flat ends that incorporates a number of different geometrical features. The evaluation of the measurement uncertainties for each characteristic was performed manually and using the Virtual CMM (VCMM) [Trapet E, Franke M, Haertig F, Schwenke H, Waeldele F, Cox M, et al. Traceability of Coordinate Measurements According to the Method of the Virtual Measuring Machine: Final Project Report MAT1-CT94-0076, PTB-Report F-35, Parts 1 and 2; 1999; Haertig F, Trapet E, Waeldele F, Wiegand U. In: Proceedings of the 5th IMEKO TC-14. Traceability of coordinate measurements according to the Virtual CMM concept; 1995. p. 245–54.]. The results show, that very low uncertainties can be achieved by the proposed measurement techniques. It is also demonstrated that the VCMM approach considers reversal effects correctly for the calculation of measurement uncertainties. 相似文献
9.
In this paper we will discuss the limit of the possible compensation for the systematic geometrical errors in large coordinate measurement machines (CMMs). One of the main problems is that the methods of measuring the errors produce errors themselves, which statistically add up to a total uncertainty of the compensation. The standard methods of error compensation cannot improve the measuring uncertainty of the machine beyond this limit, and this limit can only be reached if the reproducibility of the machine (ie the statistical error) is improved. 相似文献
10.
COORDINATE MEASURING MACHINE PROBING ACCESSIBILITY 总被引:2,自引:0,他引:2
Wu Yongqing Xie Zexiao Liu Shugui Zhang Guoxiong State Key Laboritory of Precision Measuring Technology Instrument Tianjin University 《机械工程学报(英文版)》2001,(1):45-50
0 INTRODUCTIONCoordinatemeasuringmachine (CMM )isthekeydeviceusedincomputer integrateddimensionalinspection .However,fromthe persectiveoffunctionality ,itismerelyanaccuratedigitizer ,requiringlengthy planning ,forinspectingcomplexworkpieces.In aninspection pla… 相似文献
11.
Influence of the measured objects parameters on coordinate measuring machine (CMM) touch trigger probe inaccuracy of probing is investigated. Factors such as material stiffness of measured workpiece, its surface shape and roughness are taken into consideration. The measuring method out off CMM, based on a rotary table and a reference axis is applied for tests. The concept is based on measurements of the distance between reference and triggering points in various directions. The reference points are established by the rotation of a precise rotary table. The statistical analysis of variance and regression is applied for data analysis. 相似文献
12.
Chang-Xue Jack Feng Anthony L. Saal James G. Salsbury Arnold R. Ness Gary C.S. Lin 《Precision Engineering》2007,31(2):94-101
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. 相似文献
13.
Anis Limaiem Dr Hoda E. ElMaraghy 《The International Journal of Advanced Manufacturing Technology》1997,13(2):101-108
This paper presents a general method for features accessibility analysis used in the dimensional inspection of mechanical parts by CMMs (coordinates measuring machines). It is based on the intersection of concentric spherical shells (ICSS) centred at the measurement point. This method can be applied to any type of solid or surface and is not limited by continuity or derivability constraints. Accessibility domains can be generated easily as a limit case of the ICSS. This method has been generalised to include inspection with bent probes to take into account the actual shape of the probe. It may be used to analyse the accessibility or probe approach directions for any point within or outside any object. It is also possible to determine the common accessibility domain for a set of points directly or by comparing the accessibility domain of each point. This method has potential applications in fields such as machining and robotics. 相似文献
14.
This note describes a method for measuring probe alignment errors on precision cylindrical coordinate measuring machines. Specifically, this method is used to determine the minimum distance between the line of travel of the center of a spherical probe tip and the axis of rotation of a rotary axis. Within the Timken facility, we refer to this error as intersection error [Bryan JB. Private communication; 7 June 1992]. In addition to intersection error, this method determines the position along the probe line of travel at which the center of the probe tip passes nearest to the axis of rotation. This position is commonly referred to as probe offset error. It is used to adjust the probe location such that its radial position is zero where it intersects (or nearly intersects) the axis of rotation. In this way, the probe tip location is datumed to the axis of rotation. 相似文献
15.
CMM touch trigger probes testing using a reference axis 总被引:2,自引:1,他引:2
A new method of testing of touch trigger probes for coordinate measuring machines (CMM) has been proposed. The concept is based on measurements of the distance between reference and triggering points in various directions. The reference points are established by the rotation axis of a precise rotary table. The advantage of this method relies on easy realisation with application of a commercial device for roundness error measurement. The accuracy of the presented method is much higher in comparison with the existing procedures of CMM probes calibration.The mathematical principle of the method has been presented and used for evaluation of its uncertainty. The validity of the method was experimentally confirmed by means of one- and two-stage type probes. 相似文献
16.
The error caused by the fitting of a set of data points to two lines having a specified angle is defined as the angular error. The evaluation of angular error needs to find two pairs of parallel lines that follow the angular constraint and bound the data points under the minimum zone criterion. The evaluation of angular error is difficult in mathematics, so it is usually simplified by treating one line as the datum and the form error of the other line calculated from the datum as the solution. The datum is assumed to be perfect that doesn’t tell the real properties of the actual line but gives incorrect solutions in general. To give an exact solution to the angular error problem based on the minimum zone criterion, a new mathematical model is proposed in this paper. The basic idea of this model is to rotate the data points of one line to the same direction as that of the other line so that the evaluation of angular error is simplified as solving a straightness problem. The angular error obtained from the proposed model is proved to be minimum. The proposed model offers a simple approach to solve the tough angular error problem, and it also provides a feasible tool to explore more complicated problems, like 3D angular error and polygon error. 相似文献
17.
In this paper, the probe accessibility of coordinate measuring machines (CMM) in dimensional inspection is studied. Based on the previous methods of the accessibility map, the influence of the actual configuration of the probe on the accessibility is analyzed in detail. A method, which takes the effects of the probe length and volume into account, is proposed so that the shortcomings of abstracting the probe as an infinite half-line could be overcome completely. Finally, a feasible and efficient algorithm is given. 相似文献
18.
《Measurement》2014
The purpose of this paper is to estimate the uncertainty of angle measurements using a Coordinate Measuring Machine (CMM), through the geometrical characterization of two concurrent sides of a steel angle gauge block with four perpendicular sides.For the calculation of the uncertainty associated with the measurement and investigating the errors of the CMM associated with orientation and length in the work volume, two models: linear statistical model behavior of CMM and the Mitutoyo model behavior are used and compared. After having established two behavioral models for the CMM we have determined the values of the angles and their uncertainty by using Monte Carlo Method. The results show that the proposed methods are suitable to investigate CMM hardware performance and determine the contribution of machine variables to measurement uncertainty. We can affirm that the statistical model behavior is more immediate and less laborious in terms of calculation and implementation time than the Mitutoyo model. 相似文献
19.
基于多体系统运动学理论的坐标测量机误差自动建模 总被引:1,自引:0,他引:1
研究分析了运用多体系统运动学理论对复杂机械如坐标测量机进行误差建模的基本原理,介绍了误差自动建模过程。以FXYZ型立式三坐标测量机为例进行了误差建模,给出了空间误差模型具体数学表达式。理论分析和实际应用显示所述方法很好地解决了误差建模的通用性问题,为精度分析和误差补偿等提供了一个理想的误差建模方式。 相似文献
20.
三坐标测量机动态误差与测球半径补偿误差的研究 总被引:1,自引:0,他引:1
分析了影响给定的三坐标测量机动态误差的因素,对动态偏转角误差进行了测量,并推导出由动态偏转误差得到测头处的动态位移误差的方法,同时分析了测球半径补偿误差的成因及解决措施。 相似文献