Research On Modeling Method Of Integrated Error Compensation For On-machine Measurement System Of CNC Machine Tools

Establishing accurate CNC machine tool On-machine measurement system error model is basis for improving On-machine measurement accuracy.But the grating system thermal error and guide rail system Abbe error was not considered sufficiently in the existing On-machine measurement system error model.Therefore,the grating system thermal error needs to be studied further.Besides,the Abbe arm calculation was not precisely in this model.In order to consider the correlation between spatial position,velocity and Abbe error,on the basis of CNC machine tool dynamics analysis,the Abbe error compensation model was established in accordance with the machine worktable actual motion.In traditional integrated error model based on multi-body system can't be compensated by using the numerical control system,in order to compensate the error by using the CNC machine tool three-axis linkage,the traditional error model was modified by the differential method.In order to establish an accurate grating thermal error model,the grating thermal deformation critical point theory was proposed,according to the shape heat deformation law.This has been used to improve grating fixing method and establish model of grating zero drift error and indication error.In order to analyze the variation law of the CNC machine tools Abbe error.BV75 CNC machine tool was chosen as the object,whose worktable was analyzed during the feed movement,on this basic the concept and determination method of instantaneous motion center has been proposed.Abbe error compensation model based on the instantaneous motion center was derived.In order to achieve the On-machine measurement system integrated error compensation through numerical control system.Firstly,On-machine measurement system pose matrix was established based on the differential transform.Secondly,the On-machine measurement system equivalent geometric error was solved by matrix transformation.Sometimes,the function relationship of pose matrix and equivalent geometric error was derived by Jacobian matrix.Finally,actual exercise amount of the three axes was calculated.In this paper,the machine tool model thermal deformation experiment was made by using temperature control box and inductance micrometer.The results show that the thermal deformation critical point does exist from the experiment result.The positions differ by 2.5mm,indication error and zero drift error differ by 0.2?m and 0.1?m in the actual and simulation results.This has little effect on position error.We can calculate the thermal deformation critical point by simulation method.Simultaneously,an experimental device for measuring instantaneous motion center was established by using the Laser interferometer and speed sensor.At different speeds,the determination experiment of instantaneous center and positioning error compensation experiment in the machine tool X-direction were carried out.The experimental results show that the worktable instantaneous motion center position is different at different speeds.Compared with the traditional compensation model,at the different speeds,the position error was reduced to 1~2?m by using the instantaneous motion center compensation model.The Abbe error compensation model based on the instantaneous motion can achieve higher precision position error compensation.Figure [59] table [8] reference [53]...