Research On Thermal Error Compensation Measurement And Control System Of CNC Machine Tools

Today,production and processing tend to be more precise.And the way to decrease the CNC machine tool thermal error gets more and more attention.There are many factors that affect the accuracy of CNC machine tools,of which the proportion of thermal error is 40?70%,so the research to decrease the thermal error is very important.And now,most of the CNC machine tools that are working in the factory are not equipped with thermal error compensation function.Therefore,developing a solution that can be applied to measure and compensate for thermal error in the factory workshop to improve the machining accuracy of the machine tools,has a very high social economic value.During research,we found many ways to measure the thermal error,but they all have shortcomings.For example,the laser interferometers that have been used in measuring the error is precise but expensive,complex and environment demanding.Basically,they are only for the laboratory.Contact measurement sensors such as ball rod instruments and inductive sensors are slightly shorter in some measurement scenarios and have lower accuracy than laser interferometers.Therefore,there are demand to develop CNC machine tool thermal error measurement system that can be applied to complex environments,high precision,easy to use.For CNC machine tool thermal error compensation method,basically can be divided into two kinds of way,hardware compensation and software compensation.Among them,the hardware compensation method has great limitations,such as different CNC machine tools require different hardware structures,thus the R&D costs is very high.Software compensation is divided into independent compensation card and computer-aided compensation.In contrast,computer-aided compensation requires a communication line between,the CNC machine and the computer,which presents a number of problems in a complex production workshop.Therefore,we designed our own independent compensation card based on the actual production.and it is equipped wireless communication and control functions.This paper analyzed and compared the measurement and compensation of thermal error in CNC machine tools at home and abroad,and presented the measurement scheme based on eddy current sensor and the compensation scheme using independent compensation card.Then,the paper designed the measurement system and control system,and calibrates the designed eddy current sensor through the calibration experiment to determine the measurement accuracy.Finally,the complete CNC thermal error compensation control system is applied to the Leaderway V-450 vertical CNC machining center.The experiment proves that the system can accurately measure the thermal error and compensate 90%of it.