Research On Calibration Technology Of Volumetric Errors For Coordinate Measuring Machine Based On Improving Double Ball Bar

Coordinate measuring machine as a highly efficient and convenient new precision measuring equipment,nowadays has been widely used in machinery,automotive,aerospace,electronics industry and other modern precision manufacturing industry.In order to meet the large size and complex surface parts of the detection needs,the higher requirements and challenges of the whole measurement accuracy of coordinate measuring machine will be presented.How to quickly and effectively improve the whole measurement accuracy of coordinate measuring machine is an urgent problem to be solved.The error calibration is an effective way to enhance the whole measurement accuracy.Generally,there are three main instruments for calibration the coordinate measuring machine measurement accuracy,laser interferometer,laser tracker and double ball bar.Because the laser interferometer has cumbersome measurement and long measurement period,and the laser tracker has high measurement costs and long measurement period.At the same time,the measurement function of traditional double ball bar is single and its measurement range is limited.Therefore,this paper presents a new type of measurement device which is combined with the characteristics both the traditional double ball bar and the circular gratings.According to the measurement device,the separation algorithm of linkage error is established.To achieve the global error calibration of coordinate measuring machine with data stitching,a multi-area foll coverage of the measurement method is proposed.The main study contents summarize the following three points:1.The error calibration is based on the double ball bar for coordinate measuring machine developed by our lab.Firstly,the center offset error which is inevitably generated during the measurement process.The coordinates of the center offset are solved by the least squares fitting algorithm.It is proved that the least squares fitting algorithm eliminate the center offset error through comparing the results of the center bias of the software data analysis effectively and reliably.2.In order to improve the accuracy of the error separation algorithm,the angle parameter of the traditional algorithm is estimated by the relationship between the feed rate of the coordinate measuring machine and the sampling frequency of the double ball bar.The simulation results show that the real angle acquisition is an importance of the characteristics for the coordinate measuring machine.Owing to the excellent performance of circular grating in angular position measurement,a new double ball bar measuring device with rotary angle measurement and double ball bar is designed in this paper.The calibration experiment is carried out.3.Based on the new double ball bar,a multi-area full coverage measurement method is proposed.The global error calibration of the coordinate measuring machine is realized by data stitching.Data stitching solves the problem that the limitation of the double ball bar measurement range.Finally,the feasibility of the new double ball bar stitching algorithm is verified through the calibration experiment on the coordinate measuring machine.And the feasibility of data stitching is also verified.