Research Of Thermal Characteristics For Ball Screw Feeding System Of High-Speed & High-Precision CNC Lathe

With the constant improvement of the spindle speed, the feed velocity must grow more and more rapidly to meet the high speed CNC machine tools requirement.The high-speed rotating ball screw inevitably generates a lot of friction heat, which will cause thermal error for feed system. And this thermal error of ball screw is usually one of the main components of positioning error for machine tool feeding system. Thermal error compensation technology in high-speed & high-precision CNC lathe is a key factor to improve the machining accuracy. Therefore, it is significant to have a research of thermal characteristics for ball screw feeding system.This article focuses on Jiangxi provincial key project of"Research & Development for High-speed & High-precision CNC Lathe". Thermal characteristics of the GSCK200A type high-speed CNC lathe were researched by finite element analysis software ANSYS, then the thermal stability of feeding system was validated.This thesis contains following parts.The first part is the introduction, the latest original literature concerning thermal characteristics of machine tools were extensively reviewed, which focused on the progresses in understanding thermal error compensation technology in CNC machine tools.In the second part, the mechanical structure of feed system for GSCK200A type CNC lathe was researched. Safety and reliability of the selection calculation for Z-direction ball screw were carried out. Considering low-speed rough turning and high-speed hard turning conditions, we analyzed the force condition of ball screw for feed system.The third part focused on basic theory of thermal analysis. Both steady-state heat conduction and transient heat conduction finite element equation were established according to weighted residual method. Through the reasonable simplification of ball screw, we obtained the finite element model for machine tool feeding system. In addition, parameters of the thermal physical properties were defined, and mesh generation was performed in the finite element model.The fourth part mainly discussed the heat sources and thermal boundary conditions for feed system in different working condition. Moreover, thermal characteristics of feed system for GSCK200A type CNC lathe were simulated by using the finite element software ANSYS, and the steady temperature field was also obtained.In the last part, thermal-structural coupled analysis for GSCK200A type CNC lathe was carried out based on the results of steady-state temperature field. Finally, thermal deformation of ball screw was solved exactly.The feed system of GSCK200A type CNC lathe has excellent thermal stability according to the results of finite element analysis. Moreover, it can be a significant theoretical reference for future research and development of high-speed & high-precision CNC lathe.