A V-block Three-probe Error Separation Technique For Measurement Of Cylindricity

Large cylinders are the crucial component of manufacturing equipment,of which form errors,including roundness,cylindricity and generatix straightness,will be directly copied to the large-size products and result in surface defects of large-size products.It is urgent to solve the problem of high-precision in-situ measurement of large cylindrical profiles in order to improve the technical level of national major manufacturing equipment and the market competitiveness of large-size products.Relying on the National Natural Science Foundation of China,the dissertation gives a method which is named V-block three-point probe error separation technique(VEST).This technique integrated with the laser measurement system can realize high precision protable in-situ measurement and reconstruction of cylindrical profile,and theoretically separated out full harmonic errors with the minimum number of probes.In this dissertation,adaptability and accuracy of VEST was evaluated by simulation,measurement and comparison with the measurement results of Talyrond365.Two strategies were also proposed to improve the anti-interference capability and the measurement accuracy of VEST.It can be predicted that this technique can play an active role in the future industrial measurement.Firstly,on the basis of studying and analyzing the several basic problems in the measurement of cylindrical profile,the mathematical models of VEST were established to determine the radial deviation and roundness of cross-sectional profile as will as the median line profile of cylinder.The simulations proved that VEST realizes the full harmonic error separation,and the error motions of V-block are totally eliminated,further,the correct measurement and reconstruction of cylindrical profile are obtained.Secondly,the practical measurement experiments were carried out to measure and reconstruct of two measured cylinders with different form errors by means of the self-developed VEST experimental system.The experiments shown that the measuring result in radial deviation and roundness of each cross-sectional is consistent with that of Talyrond 365.However,there still was a certain degree of distortion in measuring the median line profile by VEST.The analysis pointed out that the contact errors are an important factor of affecting the measurement accuracy of VEST.Finally,in view of the redundant measurement information of VEST,two measurement strategies were proposed to improve the anti-interference ability of VEST.The theory and simulation proved that the two strategies of VEST can effectively improve the accuracy of the median line profile of the measured cylinder.In addition,a specific index was also proposed to evaluate the reliability of a measuring procedure.It is proved that VEST is more suitable for the measuring and reconstructing cylindrical profile with the smaller surface form error.The conclusions obtained from the research on VEST can be used as the valuable reference for the high precision in-situ measurement and reconstruction of large cylindrical profile.