Least Squares Evaluations for Form and Profile Errors of Ellipse Using Coordinate Data

To improve the measurement and evaluation of form error of an elliptic section, an evaluation method based on least squares fitting is investigated to analyze the form and profile errors of an ellipse using coordinate data. Two error indicators for defining ellipticity are discussed, namely the form...

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Bibliographic Details
Published in:Chinese journal of mechanical engineering 2016-09, Vol.29 (5), p.1020-1028
Main Authors: Liu, Fei, Xu, Guanghua, Liang, Lin, Zhang, Qing, Liu, Dan
Format: Article
Language:English
Subjects:
Benchmarks
Electrical Machines and Networks
Electronics and Microelectronics
Ellipticity
Engineering
Engineering Thermodynamics
Error analysis
Heat and Mass Transfer
Indicators
Instrumentation
Least squares
Machines
Machining
Manufacturing
Mechanical Engineering
Power Electronics
Precision Measurement and Signal Processing
Processes
Theoretical and Applied Mechanics
Workpieces
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Summary:To improve the measurement and evaluation of form error of an elliptic section, an evaluation method based on least squares fitting is investigated to analyze the form and profile errors of an ellipse using coordinate data. Two error indicators for defining ellipticity are discussed, namely the form error and the profile error, and the difference between both is considered as the main parameter for evaluating machining quality of surface and profile. Because the form error and the profile error rely on different evaluation benchmarks, the major axis and the foci rather than the centre of an ellipse are used as the evaluation benchmarks and can accurately evaluate a tolerance range with the separated form error and profile error of workpiece. Additionally, an evaluation program based on the LS model is developed to extract the form error and the profile error of the elliptic section, which is well suited for separating the two errors by a standard program. Finally, the evaluation method about the form and profile errors of the ellipse is applied to the measurement of skirt line of the piston, and results indicate the effectiveness of the evaluation. This approach provides the new evaluation indicators for the measurement of form and profile errors of ellipse, which is found to have better accuracy and can thus be used to solve the difficult of the measurement and evaluation of the piston in industrial production.
ISSN:1000-9345
2192-8258
DOI:10.3901/CJME.2016.0205.022