Analysis Of Influencing Factors And Study Of Optimizing Method On Dynamic Error Of Feed System

High speed,high acceleration and high precision have become the main development direction of high-grade CNC machine tools.Feed system is the core functional component of high-speed CNC machine tool to realize spatial motion,whose dynamic performance directly affects the machining accuracy of CNC machine tool.It is an important issue to clarify the influence of mechanical and control system parameters and the coupling between them on the dynamic error of the feed system.This paper takes the electromechanical-rigid-flexible coupled dynamics model of the feed system as the carrier to carry out the analysis of the factors affecting the dynamic error of the feed system and the optimization methods.The main aspects are as follows:Based on the modal shrinkage method and the concentrated parameter method,the coupling model between the rigidity and flexibility of the mechanical system are established by considering the stiffness between the joint surfaces of the transmission parts of the feed system and the flexibility of the ball screw.Based on the vector control method,a fully closed-loop three-loop control structure is used to establish a control system model of an AC permanent magnet synchronous motor.Based on the input-output relationship between the mechanical system and the control system,an electromechanical-rigid-flexible coupling dynamic model of the feed system is established.Based on the electromechanical-rigid-flexible coupled dynamics model of the feed system,the evaluation index of the dynamic error of the feed system was developed by analyzing the response form of typical signals.Aiming at this evaluation index,the influence law of mechanical and servo control system parameters on the dynamic error of the feed system is studied.It can be known from the simulation analysis that mechanical system parameters such as lead screw lead,nut pair axial stiffness,and support bearing axial stiffness,and servo control system parameters such as position loop gain and speed loop gain are the main effects of dynamic errors in the single axis feed system.Based on the theoretical relationship between contour error and following error,the formation mechanism of dynamic contour error under typical motion trajectories is explored.On this basis,the influence of key parameters such as speed,acceleration,and position loop gain on the dynamic error of the dual-axis feed system is emphatically analyzed,providing a theoretical basis for improving the accuracy of the feed system.At the same time,considering the idea of integrated design of the mechanical and control system,based on the experimental design method,response surface method,and multi-objective optimization algorithm,the research on the optimization design method of the feed system is carried out.In this paper,an electromechanical-rigid-flexible coupling dynamic model of the feed system is established,and the influencing factors and optimization methods of the dynamic error of the feed system are studied.The research results can reveal the generation mechanism and action mechanism of the dynamic error of the feed system,and provide a scientific and effective guidance scheme for improving the dynamic accuracy of the feed system.