Machine Tool Feed System Rigid-flexible Coupling Electromechanical Co-simulation And Modal Parameters Identification

High-precision,high-speed CNC machine tools are the key products in equipment manufacturing,the ball screw feed system is widely used in the field of CNC machine tools because of its high rigidity,high stability and high precision.With the increase requirements of the quality,there are also strict requirements on the dynamic and static performance of the machine tool feed system.The feed system is a complex electromechanical coupling system.The superior performance of the control system will also greatly improve the dynamic performance of the system.This article studies the feed system from the following aspects.Firstly,based on the lumped mass method,establish a lumped mass model of the feed system,and then using the Lagrange energy method establish the system dynamics equation.The normal stiffness of the fixed joint is calculated using the Yoshimura method,based on the Hertz contact theory calculate screw nut joint and the screw bearing joint stiffness.Using ANSYS to mesh the ball screw,analyze its natural frequency and mode shape,use the rigid region method to establish a rigid region on the screw and derive a modal neutral(MNF)file.In ADAMS,the rigid body screw was replaced by the screw MNF file,add the contact friction of the joint,establish the rigid-flexible coupling model of the feed system,analysised the stick-slip phenomenon of feed system rigid-flexible coupled model.Secondly,a permanent magnet AC synchronous motor is established in a d-q coordinate system and a three-loop PID control model for the electromechanical coupling of feed system is established.Set current loop,speed loop,position loop controller parameters,obtained the better PID control parameters.Impact on nonlinear friction force in machine tool feed system,applying Stribeck friction troque in electromechanical co-simulation system,obtained the influence of nonlinear friction force on low speed motion of servo feed system,and the zero-crossing phenomenon in the speed response when tracking a sinusoidal displacement signal.Finally,in the Workbench,spring elements are used to simulate the stiffness of the joints.Simulation modal analysis is performed to obtain the first six natural frequencies and modes.Simulate the change of the position of the worktable and the change of the load quality in the actual machining,and calculate the modal parameters of the feed system.Build an experimental platform for the feed system was set up,using the DEWEsoft dynamic tester performed modal esperiments.The simulation results are compared with the experimental natural frequency of the feed system.Verified the correctness of the simulation results and the rationality of processing by the binding department.For feed system parameter identification,through experiments obtained the speed and acceleration curves of feed system at different speed,used the least squares method identify the stiffness and damping of the system at different position.