Measuring Method And Technology Of Radial Motion Error Of Rotating Shaft By Laser Interferometry

CNC machine tools are the cornerstone of national manufacturing production and processing.Three-axis CNC machine tools and five-axis CNC machine tools are common.Among them,five-axis CNC machine tools include rotatable shafts,which can achieve accurate operations in all aspects,so they are more widely used.The accuracy of the rotating shaft directly determines the machining and manufacturing accuracy of the CNC machine tool.Measuring and compensating for the motion error of the rotating shaft is an effective means to improve the accuracy of the rotating shaft.At present,the main way to realize the six-degree-of-freedom measurement of the rotating shaft is the step-by-step measurement,which is not only time-consuming and labor-intensive,but also introduces more installation errors.The existing research on the six-degree-of-freedom motion error measurement method of the rotating shaft generally has complicated installation and debugging,and needs complicated Decoupling and high price defects make it difficult to be widely used.Our research group has realized the simultaneous measurement of the geometric motion error of the rotating shaft with six degrees of freedom based on the He-Ne laser.The five-degree-of-freedom measurement of the rotating shaft is based on the principle of optical collimation,and the radial motion error measurement of the rotating shaft combining laser interference and servo tracking is proposed.The method realizes the full circumference measurement of the 360° radial motion error of the rotating shaft while ensuring the continuity of the interference signal.Since the measuring arm is collinear with the radial movement direction of the rotating shaft in the interferometric method,an error-sensitive unit can be shared,thereby realizing simultaneous measurement of six degrees of freedom.In this measurement scheme,helium-neon laser is used as the laser light source,which is large in size and high in cost.Due to the use of commercial laser interferometers,the interferometric signal characteristics and data processing methods of the radial motion of the rotating shaft have not been thoroughly studied.In order to meet the requirements of high precision,low cost and easy integration for the simultaneous measurement of the motion error of the rotating shaft with six degrees of freedom,this paper proposes an interferometric measurement method for the radial motion error of the rotating shaft based on a semiconductor laser,and studies the interferometric measurement of the radial motion error of the rotating shaft.High precision solution of the signal.The main research work of this paper is as follows:1.The research and realization of the radial motion error measurement method with the simultaneous measurement of the six-degree-of-freedom error of the rotating shaft,using a semiconductor laser for interferometric measurement,installing a corner prism on the servo rotating shaft as a measurement sensitive unit,measuring the radial movement direction of the light and the rotating shaft Collinear,the method of laser interference length measurement is used to measure the radial motion error,and the radial motion error measurement of the 360° full circumference of the rotating shaft to be measured is realized by the reversal of the servo shaft.2.The laser interferometric measurement system for the radial motion error of the rotating shaft is developed,including the optical system design and optical path debugging and installation,the selection of photoelectric detectors and the connection of driving circuit debugging.Control the rotation of the shaft to be measured and the servo shaft by controlling the software of the upper computer,use the NI acquisition card to perform real-time online data acquisition through the acquisition program of the Lab VIEW software,and then use the powerful MATLAB data analysis and simulation software to digitally filter the interference signal.Linear error correction and phase interpolation and resolution.3.A method of peak-valley extraction in signal nonlinear correction based on zero-value interception-threshold judgment is proposed.The reason of phase jitter in the process of signal processing for the radial motion error of the rotating shaft is analyzed,and the influence of phase jitter on the nonlinear error correction and phase solution of the interference signal is studied.The proposed method is used to accurately intercept and correct the correction period.The calculation of the coefficients,through the Lissajous figure,verifies the validity of the correction algorithm proposed in this paper.4.The experimental study of the laser interferometry of the radial motion error of the rotating shaft is completed.The experimental results show that the repeatability value of the radial motion error of the rotating shaft of the system is reduced to 0.34μm compared with 4.72μm of the traditional algorithm.In the comparison experiment,the maximum comparison error with the standard instrument was reduced from 3.55μm to1.64μm,which verifies the effectiveness of the method.Theoretical analysis and experiments show that the radial motion error measurement scheme of the rotating shaft based on the semiconductor laser proposed in this paper can meet the measurement requirements of simultaneous measurement of the rotating shaft with six degrees of freedom,and provides a guarantee for the maintenance of CNC machine tools and the realization of accurate operation.