| The rapid development of advanced equipment manufacturing industry greatly increase the demand of ultra-precision cylindrical specimen.There are two main problems that affect the ultra-precision measurement of cylindrical contours: First,the circular contours of many cylindrical specimens are discontinuous,while traditional roundness assessment method is mainly designed for completed circular contour evaluation.Second,the accuracy of the position adjustment is limited by the positioning adjustment system.Due to driving and positioning error and other factors,there is still a large axis incline residual error.This two aspects become a great constraint of precision measurement of nonholonomic circular contour and precise measurement of cylindrical contours.In order to solve problems as mentioned,this thesis has made theoretical analysis,simulations and experimental work of the nonholonomic circular contour roundness measurement and tilt error separation in the cylindrical measurement.The main work done in this paper are as follows:Established roundness error evaluation model of nonholonomic circular contours.Studied the algebraic fitting method based on least squares principle,and improved this circular fitting method based on radius constraint.Simulations and experiments results show that this method is correct and the accuracy of the method is higher than using traditional method after compensation when the arc is bigger than 50% full circle and the eccentric is relatively obvious.Proposed the axis incline error separation method of cylindricity measurement.The basic principle of this method is through the spatial line fitting to find specimen axis,and established cylindrical contour measurement model including tilt error.Analysis the function relations of incline error with the sampling angel and radius.Bring up with an error compensation based on this mode,which can separate the axis incline error from the original measurement data by compensation point-bypoint.The experimental results show that the error separation method can separates the incline angel and incline error from measurement data and the relative deviation is less than 5% when the axis incline is less than 300 seconds,and the real characteristics of the measured contour can be obtained accurately.Developed software for nonholonomic circular contour roundness evaluation and axis incline error separation and compensation.This package is based on VS platform and c # language,containing the measurement data acquisition,transmission,motion control,measurement,data processing,the measurement results and gr aphic printing and storage module.this software package has been inserted in the cylindricity measuring instrument used for the actual measurements. |
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