Analysis Of Nonlinear Dynamic Characteristics Of Ball Screw Feed System Considering Thermal Deformation

The dynamic accuracy of the CNC machine tool feed system directly determines the machining accuracy of the entire CNC machine tool.With the continuous development of CNC machine tools in the direction of high-speed,the relatively high-speed motion of bearings and screw nuts will generate a lot of heat,and together with the dynamic force will induce the thermal dynamic error,which greatly reduces the dynamic accuracy of the feed system.In response to this problem,this paper takes the ball screw feed system as the research object,and develops the nonlinear dynamics modeling and analysis of the ball screw feed system considering thermal deformation.The main research contents are as follows:(1)The temperature field model of the ball screw feed system is established,and a new analytical solution method for the temperature field and thermal deformation is proposed and verified by experiments.First determine the thermal boundary conditions of the temperature field,process the bearing and nut temperatures collected in the experiment by polynomial fitting,obtain the temperature function that changes with time,and substitute it into the heat conduction equation of the ball screw feed system to solve it,and get the system The temperature field function and thermal deformation.Then use experiments to verify the accuracy of the established theoretical model.Finally,the influence of some parameters on the temperature field and thermal deformation of the ball screw feed system is also discussed.(2)A dynamic model of the ball screw feed system considering thermal deformation was established and verified by experiments.Based on the Hertz contact theory,the thermal deformation of each component of the ball screw feed system is taken into account in the dynamic model,and the nonlinear dynamic model of the system under thermal deformation is established,and a new dynamic equation is obtained.The vibration response signal measured by the experiment is compared with the numerical result of the theoretical simulation,which verifies the correctness of the dynamic model and provides a theoretical basis for the subsequent analysis of dynamic characteristics.(3)Analysis of the dynamic characteristics of the ball screw feed system.The difference between the vibration characteristics of the feed system without considering thermal deformation and considering thermal deformation is analyzed.The influence of different excitation frequencies and amplitude values on the vibration characteristics of the system when thermal deformation is considered is discussed.Finally,the influence of different initial contact angles,different ball diameters and different ball numbers on the vibration characteristics of the system is discussed.Through the research in this paper,a dynamic model of the ball screw feed system under thermal deformation is established,and the effect of thermal deformation on the vibration characteristics of the system is analyzed.The effect of preload,initial contact angle and external excitation on the dynamic performance of the system is also analyzed.,It has important guiding significance for reducing the vibration response of the ball screw feed system and improving the dynamic performance index of the system.