Effect of Eccentricity on Roundness Measurement Accuracy for Cylindrical Components with Large Radius
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ORIGINAL ARTICLE
Effect of Eccentricity on Roundness Measurement Accuracy for Cylindrical Components with Large Radius H.-H. Tian*, Y.-X. Wang and H.-X. Wang School of Mechatronic Engineering, Xi’an Technological University, Xi’an 710021, China Received: 25 December 2019 / Accepted: 22 May 2020 Metrology Society of India 2020
Abstract: The eccentricity, difficult to adjust for components with a large radius, can lead to roundness measurement distortion. In this paper, the effects of the eccentricity and radius of components were simultaneously analyzed in the roundness measurement. The derived mathematical relationships between roundness measurement error, eccentricity and radius of components were represented graphically. Simulation results show that the larger the radius of components, the greater eccentricity is allowed for a constant roundness measurement accuracy. There is no need to decrease the eccentricity to obtain relatively higher measurement accuracy of roundness for components with a large radius. This is expected to provide insights into the future design and manufacture of large size alignment mechanisms. Keywords: Roundness; Eccentricity; Measurement accuracy; Large radius 1. Introduction Roundness is one of the most basic functional product features of mechanical parts. ISO12181 defines the terms and concepts related to the roundness, specified the complete specification operator for roundness of integral features and covered complete roundness profiles [1, 2]. Roundness error indicates the radius difference between two concentric circles containing the ideal one of a cross section profile. Whether roundness error can be measured accurately or not will directly influence the mechanical parts performance and life [3, 4]. The most used methods to determine roundness errors are (ANSI Y14.5 M, 1994): minimum zone circle method(MZC), least-squares circle method(LSC), minimum circumscribed circle method(MCC) and maximum inscribed circle method(MIC). Among the four methods, the LSC is the most widely used method in roundness evaluation in view of the simplicity of its application [5, 6]. Roundness error is usually measured by so-called radial methods [7]. In the radial method, roundness error is measured in respect to the axis of the rotary table. The eccentricity, caused by the misalignment between the workpiece center and spindle axis, has great influences on
*Corresponding author, E-mail: tianhuihui@xatu.edu.cn
measurement accuracy [8, 9]. The widely used limacon approximation to the profile of a truly circular workpiece could compensate the effect of the first harmonic of eccentricity [10–12]. However, the influence of eccentricity can still present itself in the other harmonics [13]. The improvement of roundness measurement accuracy has received substantial attention in the literature [14–16]. Many researchers pay attention to improve the accuracy of roundness measurement based on rotary tables of radial instruments. Taylor Hobson, the major manufacturer of roundness measurement instruments, de
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