精密研抛数控机床几何误差与热误差复合建模及其补偿研究

Compound Modeling and Compensation of Geometric Error and Thermal Error for Precision Polishing CNC Machine Tool

为了提高精密研抛数控机床的加工精度,对研抛数控机床的几何误差与热误差进行了研究与分析,发现随着机床相关部件温度的不断升高直至热稳态,机床的定位误差也不断增加到稳态值,验证了几何误差和热误差是精密及超精密加工误差的主要来源。综合考虑了机床复合误差的不同特点并进行误差分离,提出了基于牛顿插值算法和最小二乘法的几何与热复合误差建模方法,依据复合误差模型进行补偿实验,补偿后机床冷态下定位误差值从3.5μm降至1.2μm,误差降低了65.7%,热稳态后定位误差值从12.2μm降至1.9μm,误差降低了84.4%,实验结果证明复合误差模型计算简单、预测精度高、具有较好的鲁棒性,为提高机床的加工精度提供了理论与实践依据。

In order to improve the accuracy of precision polishing CNC machine tool,through analysis and study on geometric error and thermal error of polishing CNC machine tool,it is found that as the temperature rising to the heat steady-state of machine tool parts,the positioning error increase to steady value constantly,to verify the geometric and thermal error are the main source of precision and ultra precision machining.Considering the different characteristic of machine tool comprehensive error,error separation is carried out,a compound modeling method of geometric and thermal error was presented based on least square method and Newton interpolation,using this compound error model for error compensation experiments,the positioning error of machine tool in normal temperature is reduced from 3. 5μm to12. 2μm,the error have been decreased 65. 7%,the positioning error is reduced from 12. 2μm to1. 9μm after heat stable,the error have been decreased 84. 4%. The experimental results showthat the compound error model is convenient in calculation,and high accuracy of prediction and better robustness,and provides a theoretical and practice basis for accuracy of machine tool.