Analysis And Research On The Measurement System For NC Machine Tool Fault

In this dissertation, a novel NC machine tools error model and identification method are developed, based on understanding and analyzing the status of the reaseach and application in this field. In any experiment, analyzed the motion error of NC machine tools while it do a straight line trace motion, or circle trace motion and complicated trace motion. The main contributions of this dissertation are shown as follows: Established a synthetic kinematical model based on the theory of body kinetics system and the theory of homogeneous transformation. The detail including:The error mechanisms of main componets in NC machine tools, which including link, prismatic joint and rotory joint, are analysed in detail to derive thehomogeneous transformation. The synthetic error model is developed based on the previous analysis. Further more, the mapping relationships between the error components and radial motion error of circular workpiece manufactured on the machine tools are proposed to trace the error source.Analyzed the phenomenon of creeping in low feed velocities and the influence which the low feed velocities to the positions accuracy. Analyzed the reason of creeping based on the kinetics model of feed drive system, using Renishaw laser interferometer system dynamic measure the phenomenon of creeping, put forward the method of control creeping phenomenon. Make use of the Heidenhain flat grid system, analyzed the influence which the low feed velocities to the positions accuracy through the designing of straight line connection experiment, and conclude that the position error increasing with the increment of the feed velocities.Based on the measurement system of Heidenhain grid encoder, Analyzed circular locus errors in different feed velocity and circular radius affect. Combine the circle comprehensive error, anylased the theories circular error locus picture caused by backlash, ball screw, the noised in detectors, servo response lag and mismatch of positioning loop gain. And the comprehensive circle error picture gain by experiment and theories picture is fit together, which proved the model builted in the second part is correct.Design the square locus and complicated locus, make use of the Heidenhain flat grid system, measure the motion error while machine make the square locus and complicated locus. Analyzed the influence of feed velocities to the right angle; analysed the influced of feed rate and radius to curvature motion error in condition of high feed rate and large scale.