The Multi-domain Modeling And Simulation Research Of High Speed Machine Tool Feed Drive Based On Sliding Mode Control

Feed drives are used to position the machine tool components carrying the cutting tool and workpiece to the desired location; hence their positioning accuracy and speed determine the quality and productivity of machine tools. Feed drive is a complex system consisting of multidisciplinary fields of mechanical, electrical, control and other configuration. The movement and power parameters of mechanical subsystems have strong coupling relationship with the parameters of electrical subsystems; and the control parameters in the role of non-linear electrical systems and control law, also have effects on the dynamic characteristics of the mechanical system. With the improvement of high-end CNC machine tool feed speed, acceleration and positioning accuracy requirements, high-speed feed drive multi-domain coupling becomes more volatile and have a significant impact on the system dynamics. Only a single field analysis model has been difficult to meet research needs. In this paper, the study of the whole high-speed feed systems modeling simulation is carried out, to explore the precision control strategy and the building of multi-domain simulation model. Specific works are as follows:Based on the modular modeling concept, the feed drive is divided into multi-domain modules. Firstly the mechanical, electrical domain model library of feed drive are established based on a unified simulation platform Mworks. The screw parameters is calculated through finite element analysis, which is more targeted and credibility than through traditional empirical formula. Secondly, the position, speed and current closed-loop control of permanent magnet synchronous motor(PMSM) servo control system is built. And by simulation, the feasibility and shortcomings of traditional PI control strategy are analyzed.In order to increase the servo bandwidth and ensure the stability of system, the position, speed and current closed-loop PI control of PMSM servo control system is built. A PMSM servo system speed loop and position loop controller are established based on sliding mode control theory. And for the chattering problem of sliding mode control, a variable gain sliding mode controller is designed and combined with the traditional PI control. The simulation results compared with PI control shows that the new piecewise variable gain sliding mode controller has better robustness and anti-jamming capability.To achieve the multi-parameter coupling between subsystems, the domain interface model library is established and thus the ball screw feed drive multi-domain co-simulation model is built. Based on the uniaxial co-simulation model, the ball screw biaxially synchronize simulation model is also built. The simulation results verify the feasibility and effectiveness of each model, provide a reference value to the selection of the feed system components and parameter optimization.This study on the CNC machine tool feed system of R & D has a good reference, provides a new idea to comprehensively improve the high speed and high precision CNC machine tools. The research method is also applicable to the machine tool spindle servo system.