Analysis And Experimental Study Of Dynamic Characteristics Of Dual-driving Feed System

As the basic control unit and key transmission components of CNC equipment,the dynamic characteristics of the feed system will directly affect the working performance of CNC equipment.The dual-driving feed system based on the center of gravity drive principle uses dual motors to jointly drive the table movement in the direction of single degree of freedom,which overcomes the defect that the traditional single motor driving force cannot accurately affect the center of gravity of moving parts.The dual-driving feed system has good resistance to system deformation and the ability of high-speed and high-precision feeding.It is an important research direction of advanced CNC equipment.Therefore,this article takes the dual-driving feed system as the research object,and uses theoretical calculations,electromechanical joint simulation and experimental verification to study the dynamic characteristics of the dual-driving feed system from the perspective of mechanical structure parameters and synchronous control strategies.It lays theoretical and technical foundation for improving the dynamic characteristics of the system.The main research contents and results are as follows:(1)The principle of center-of-gravity drive and the components of the dualdriving feed system are introduced,then the equivalent stiffness characteristics of lead screw drive chain are analyzed.Considering the influence of the joint stiffness and the coupling vibration in the space,a three-dimensional parametric dynamic model of the dual-driving feed system is established,and the rigid body mode of the model is expressed analytically.The mechanical simulation model of the dual-driving feed system was established by the state space method,which provided a model basis for the subsequent dynamic characteristics analysis.(2)Based on Hertz contact theory,the stiffness models of the ball screw joint,rolling bearing joint and rolling guide joint in the system were established respectively.The natural frequencies and mode shapes of each order of the dual-driving feed system were predicted.The influence of the mechanical structure parameters such as the quality,position and topology of the worktable on the dynamic characteristics of the system is analyzed.It provides a theoretical reference for the structural design and optimization of the dual-driving feed system.(3)A mathematical model of the AC servo motor and its three rings is established.Based on the single-axis PID servo control system,master-slave synchronization,cross-coupling synchronization,and single neuron PID synchronization control models are established.Considering the relationship of the input and output between the control system and mechanical simulation model,an electromechanical joint simulation model of the dual-driving feed system was constructed,and the dynamic performance of the dual-driving feed system under different synchronization control strategy was analyzed.(4)The construction of the test bed for the dual-driving feed system was completed,then the modal test of the dual-driving feed system is carried out.The accuracy of the dynamic model is verified by comparing the natural frequency and mode shape of the system detected by experiment and predicted by theory;The single axis PID performance test and the dual-driving feed system synchronous control test are carried out.The effects of different synchronous control strategies on the dynamic performance of the dual-driving feed system were analyzed,and servo parameters and synchronization control strategies that optimize the dynamic characteristics of the dualdriving feed system were obtained.