Real-time thermo-mechanical dynamics model of a ball screw system based on a dynamic thermal network

The ball screw system operates under the coupling condition of external loads, preloads, and thermal loads, and its thermo-mechanical characteristics significantly affect its dynamics performance. Therefore, a thermal-mechanical real-time dynamics model is necessary. In this work, the screw systems thermo-mechanical coupling mechanism was first analysed. Second, a new dynamic thermal network model for the screw system with moving heat excitation was proposed using the position of the moving nut obtained by FANUC Open CNC API Specifications (FOCAS), which can rapidly determine the transient temperature field. Based on this model, a new thermo-mechanical coupling real-time dynamics model of the screw system was established. The influence of temperature on dynamics characteristics was analysed using the dynamics model, and the results showed that the system preload caused by thermal elongation of the screw decreases with an increase in temperature. The system preload caused by the thermal deformation of the bearing increases with an increase in temperature. The total preload of the system depends on the interaction between the thermal deformation of the screw and the axial thermal deformation of the bearing. Additionally, the system stiffness and natural frequency variation relative to the increase in temperature and position of the carriage were obtained. Thermo-mechanical dynamics performance experiments of the feed system were carried out to validate the effectiveness of the proposed model.