Research On Synchronous Detection System Of Tool Posture And Motion Error For Five Axis CNC Machine Tool

The kinematic accuracy is an important indicator to evaluate the process ability of CNC,and also largely determines the machining quality of part. The detection method with instrument has widely been applied in examination of the kinematic accuracy of machine tools as an efficient and convenient method. While, for the examination of five axis CNC machine tools, the boundedness and complicacy of those existing methods become obviously.Since now most of the five axis NC machine tools have equipped with the RTCP(Rotation tool center point) function. A RTCP trajectory would result the machine tool tip unmoving to the work piece coordinate system. While the axes of machine tool are moving in a large range at the same time. Based on this function the R-test detector has been developed, because in a small measurement space the accuracy is improved and the process of detection is simplified. But it is only suitable to detect the motion error of the machine tool. There is unstable delay between the position of each axis and the record of motion error. So that, the R-test is unable to provide a more favorable data to adjust parameter and trace the malfunction source of machine tool. To solve this problem, a scheme to detects five axis machine tool motion error and tool posture synchronous in real-time is proposed. The main research contents of this paper include the following aspects:1) Based on the position constraint relationship of rotation axes and the translation axes in a RTCP trajectory, the feasibility of the synchronous detection scheme of five axis machine tool motion error and tool posture is analyzed. Besides, the inaccuracy of the measurement results caused by the delay in those current detection schemes is analyzed. And the necessity of synchronous detection is shown.2) According to the functional requirements of the detector, the method of motion decomposition is used to design the structure of the detector. And the detailed design of the mechanical structure of the synchronous detector is completed. Besides, those key components have been selected. Combining the structure of the motion error measurement part the mathematical model is built, the maximum effective measurable space and the measurement sensitivity are analyzed, and the key structural parameters of the motion error measurement part are presented.3) Based on the error modeling method of multi-body system theory, the measurement accuracy mathematical model of motion error and attitude angle are built. And according to the mathematical model, the influence rules of each error are simulated and analyzed.4) By analyzing those simulation curves, the primary and secondary error elements contained in the detector are shown. By constructing the radial dimension chain of the shaft system, the uncertainty of the radial runout error of the shaft system is calculated in many cases. The influence of the error in the ball head on the measurement results is analyzed, and the calibration method of the ball head rotation error is proposed...