The Design Of A Five-degree-of-freedom Geometric Errors Measurement System For Machine Tool Worktable

With the development of modern industrial technology,people have put forward more accurate requirements for the machining accuracy of CNC machine tools.Due to the influence of the factors such as the processing and assembly errors of the guideway,there will be 6-DOF geometric errors when the machine tool table moves along a certain direction axis,which directly affects the processing accuracy of the workpiece on the table.The accurate measurement of the 6-DOF geometric errors is an important means to ensure and improve the machining accuracy of the machine.Therefore,the development of a multi-degree-of-freedom geometric error simultaneous measurement system for machine tool worktable is of great significance for improving the accuracy of machine tools.This thesis proposes a simultaneous measurement method for 5-DOF geometric errors of machine tool table with small volume,low cost,long measuring distance and high precision for common CNC machine tools based on laser collimation principle and self-collimation principle.And the complete measurement system was built to measure the five geometric errors in addition to the position error that the machine itself can measure.Firstly,the cost of the whole system is effectively reduced and the volume of the system is reduced by choosing the optical elements reasonably.Secondly,according to the requirements of the measurement system,the hardware circuit of the system is designed.The functions of I/V conversion,AD acquisition and wireless data transmission are realized.The purpose of accurate measurement and no cable connection between the measurement terminal and the host computer are achieved,thus meeting the requirements of high precision and long distance measurement.Finally,based on LabVIEW,the upper computer program of the measurement system is programmed to realize data acquisition,filtering processing,data display and data saving.In order to verify whether the performance of the measurement system meets the measurement requirements of ordinary machine tools,the calibration experiment,stability experiment,comparative experiment and repeatability experiment of the measurement system are carried out.The experimental results show that the straightness calibration residual of the system is less than ±0.6μm,the angle calibration residual is less than ±0.8″,the straightness comparison error is less than ±1μm,the angle comparison error is less than ±2.0″,the offset of the straightness and angle within 60 minutes is 0.6μm and 0.3″,and the repeatability of the straightness and angle error of the measurement system is less than 2.5μm and 2.5″,respectively.It is proved that the system has reliable stability,high accuracy and good repeatability under the circumstance of measuring distance of 1000 mm.