Thermal Analysis And Thermal Deformation Compensation For Ballscrew System Of Machine Tools

Positioning accuracy of CNC machine tool is an important criterion to reflect the performance of machine tool, and it is also an important factor which can affect the machining accuracy.Because of thermal deformation generated by relative motion between ball screw and nut, and the bearing, the positioning accuracy is seriously affected.The thermal deformation of the ballscrew is changeable differently because of the changeablity of job situations. The thermal deformation of the ballscrew is changeable differently. According to the ballscrew system of a machine tool, first, establish a finite element analysis model to analyse the thermal properties of ballscrew, using the finite element method, then provide theoretical basises for compensation of thermal deformation. Second, analyse the characteristics of ballscrew movements, design an experiment for compensation of thermal deformation, then take a reserch for compensation of thermal deformation using multiple linear regression methods, such as following aspects.1. Establish a mathematical model of three-dimensional temperature field for ballscrew system, and base a mathematical model of heat distortion on the knowledge of elasticity, heat deformation basic equation and finite element theory.2. Establish a three-dimensional CAD model for component ballscrew systems, and have a discussion on finite element meshing and heat conduction between combined surfaces, then establish a finite element model for heat conduction, and lay a foundation for CAE analysis.3. Establish a finite element model for temperature field after analyzing the internal heat source and the boundary conditions.make a detailed analysis for the temperature field and heat distortion of the system, then provide a strong theoretical basis for the thermal deformation compensation of ballscrew system.4. Design a thermal compensation package according to the thermal characteristic results of finite element analysis, and design the layout of the temperature measurement points taking advantage of the relativity of the temperature of nods and the heat drift of ballScrew, establish a thermal error compensation model of ballscrew system to numerical control tool, using multiple linear regression methods, and develope a modeling software module for it. The paper makes a useful contribution to the establishment ofthermal characteristics of ballscrew system finite element mathematical model, and the research of ballscrew system thermal deformation compensation. The correctness of the theoretical analysis results are verified by comparing the results between the finite element analysis and experiment. The result shows that the thermal deformation of the ball screw system has achieved the requirement of the compensation accuracy through the study of the compensation of thermal deformation error of the system.