Research On Characteristics Of Machine Tool Feed System Based On Stiffness Characteristics Of Joints

The machine tool feed system is an important part of the machine tool.It is an important research hotspot to analyze and study its dynamic performance,realize the optimization and adjustment of the mechanical structure,drive and numerical control system of the feed system,and improve the working performance of the machine tool.This paper is based on the self-designed CNC machine tool feed system test bench,focusing on the characteristics of the feed system considering the bolt joint and the motion joint,which has important theoretical significance and work application value.The stiffness parameters of the bolt joint was identified.The bolt joint is equivalent to the spring-damper unit,and the finite element model of the single bolt connection plate is established.Based on the finite element modal analysis and the experimental modal analysis,the stiffness parameters of the joint are identified.On this basis,a parametric model of single bolted plates was constructed to solve the repetitive modeling work in the analysis process,which laid a foundation for parametric modeling of the experimental platform.The finite element model of the ball screw pair and the rolling guide in the experimental platform was established.The Hertz contact theory is used to solve the stiffness parameters of the joints of the ball screw pair and the rolling guide pair,and the dynamic model is established to provide a basis for the establishment of the finite element model.Through the modal analysis and harmonic response analysis,the allowable rotational speed of the ball screw pair without resonance is obtained,and the relationship between the vibration amplitude and the load of the ball screw pair and the rolling guide pair is obtained.A finite element model of the feed system experimental platform was established.The modeling method of bolt joint,ball screw pair and rolling guide pair is applied to the finite element model of the system.The modal analysis of the whole experimental platform is completed,and the validity of the established model is verified by experiments.Based on the harmonic response analysis of the system,the amplitude-frequency curve of the machine tool feed system at different working positions is obtained.The research results have an important reference value for the reasonable selection of the load when the system works to reduce the vibration.