Research On The Friction Compensation And Servo Optimization Of The MVC850B Cnc Milling Machine

With the concept of "Industry 4.0" and the strategy of "Made in China 2025",the advanced manufacturing industry has higher requirements on the performance for the CNC milling machine.How to improve the processing accuracy has become the key problem.The performance of the feed servo system affects the machining accuracy,especially the positioning error and tracking error,which are two main aspects that restrict the improvement of machining accuracy.In the feed servo system,the clearance error and friction error as well as the servo driving performance are the key factors that affect the positioning accuracy of the feed axis and the tracking accuracy of the system.In order to improve the machining accuracy and stability for the CNC milling machine,this thesis will focus on the error measurement and error compensation as well as the servo optimization.The main research work includes:(1)The analysis and experimental research of the positioning error compensation strategy based on the reverse clearance and pitch error.Aiming at the problem of positioning error,this thesis takes the MVC850B CNC milling machine as the experimental platform.And it uses a laser interferometer to build the measurement and compensation system of positioning error for the feed shaft.Through the measurement analysis and compensation experiment of the reverse clearance and pitch error,it will improve the positioning accuracy of feed shaft for the CNC milling machine.(2)The friction compensation of the CNC milling machine servo system based on the fractional sliding mode control is proposed.In order to compensate the nonlinear friction which affects the performance of the feed servo system for the CNC milling machine and to establish a servo system with good dynamic performance,this thesis proposes a fractional order sliding mode control friction compensation strategy.By introducing the fractional calculus operator into the traditional sliding mode control,it can overcome the defects of the traditional friction compensation method for the unknown modeling error and weak anti-interference ability.(3)The analysis and experimental research on the optimization strategy of feed servo system for the CNC milling machine.In order to further improve the stability and machining accuracy of the CNC milling machine,this thesis intends to study the related methods and experiments of the feed servo system optimization.Through the measurement and analysis of the servo vibration frequency,running current,quadrant bulge and other curves,we use the servo guide software to optimize the servo parameters.This thesis focuses on the machining accuracy of the CNC milling machine.Combining the fractional order control technology and advanced detection technology,the theoretical analysis and experimental research of the error measurement compensation and servo optimization are carried out.