A Method For On-line Measuring Motion Errors Of A Machine Linear Slide And Experimental Verification

High-end CNC machine tools not only play a significant role in the areas of aerospace,military and nuclear industry;but also are a critical factor for breakthroughs in the fields of inertial confinement fus ion,micro-electronics,high performance parts precision machining.Linear guide is essential for the high-end CNC machine tools to achieve the translational motion.Quick and accurate online motion error detection of the linear guide can not only improve the machining accuracy of the machine tool through error compensation,but also monitor the running status of the machine tool.Therefore,the related research has great engineering significance and scientific value.To solve the problem,this paper proposes an on-line linear guide motion error measurement method which are integrated by error separation algorithm and error detection system.The key technologies are studied in depth from theoretical derivation,simulation analysis and experimental research.Aiming at the limitation of the existing multi-probe scanning error separation method,an improved four-point algorithm is proposed to simultaneously measure the straightness error and yaw error of the guideway.The probes are arranged in a specific way,and a full rank linear equation group is established based on the probe measurements.To solve the problem of instability caused by the ill-conditioned nature of the system of equations,a Tikhonov regularization method was introduced.Matlab simulation analyses show that the improved four-point method has ideal calculation accuracy.The system analyzes the influence of parameters such as noise,sampling interval,number of sampling points on the improved four-point method,and the simulation results show that the measurement noise has the greatest influence on the accuracy of the algorithm.According to the functional requirements of the improved four-point method,a matched flexible error detection mechanism is designed and its characteristics are analyzed.Firstly,based on the typical flexible mechanism,the error detection mechanism is configured and integrated.Secondly,based on the flexibility matrix of the flexible hinge,the flexibility model is used to derive the flexibility model of the series/parallel flexible mechanism,and then the flexibility model of the orientation module and the amplification module in the error detection mechanism is established.Then,according to the above model,the key parameters of the output displacement,input stiffness and other geometrical dimensions are simulated and analyzed.Finally,finite element method is used to analyze the dynamic and static characteristics of the error detection mechanism,and the key performance indicators such as the magnification and natural frequency of the mechanism are obtained.Experimental study of the motion error online detection method is proposed to verify the feasibility and effectiveness of the method in this paper.First,the error detection system is constructed based on the flexible error detection mechanism and linear scale.Second,the error detection system magnification,input stiffness and natural frequency are measured.Finally,the linearity error and the yaw error of the machine tool guide rail are determined by applying the on-line error detection method and the laser interferometer.And the space tran sformation relationship of the two errors is established to verify the effectiveness of the proposed method in online error detection of machine tool motion.The experimental results show that the on-line detection method can effectively separate the movem ent errors of the machine tool guide rail.