Study Of Thermal Characteristics On The XK717 CNC Milling Machine

With the development of machine tools in higher speed and higher precision, the thermal characteristic of machine tools is becoming more and more important. Many kinds of the heat sources (frictional heat, cutting heat, ambient temperature, etc) in machining system produce a kind of temperature distribution. This temperature distribution induces thermal deformation between machine tools, tool, work-piece and work holding fixture. This deformation affects the relative displacement between the work piece and the cutter, causes the manufacturing errors, and influences the machining accuracy of the work-piece. From J. Peclenik's investigation, thermal errors accounts for 40%-70% in the precision machining. Therefore, it is very important to reduce thermal deformation and improve the machining accuracy in the design of machine tools, hi this paper, thermal characteristics of XK717 CNC milling machine are analyzed by using the finite element method, supported by a key project of Zhejiang Province.In chapter 1, heat sources in machining system, countermeasure of improving thermal deformation and the study of thermal behavior on the spindle system have been summarized. The background of the project and main contents of this paper have been introduced.In chapter 2, heat conduction and thermal deformation theory are introduced. And then, the finite element method about temperature field and thermal deformation is summarized.In chapter 3, empirical model of the thermal boundary conditions is analyzed onthe CNC milling machine. Process and method of thermal behaviors is discussed on XK717 CNC milling machine and its spindle system.In chapter 4, thermal characteristics of XK717 CNC milling machine are simulated and the result provides the basis to improve thermal behaviors for design of CNC milling machines compared with XK510 CNC milling machine.In chapter 5, thermal characteristics of spindle system with cooling jacket are analyzed on XK717 CNC milling machine by combining 3D finite element model with the temperature model of cooling water between spindle system and water tank. The effect factors to thermal behavior of the main spindle system are studied by analyzing both cooling parameters and structure.Finally, the main conclusions and prospects for the future research are presented.