基于EFAST方法的三坐标数控机床几何精度灵敏度分析

Sensitivity Analysis of Geometric Accuracy of Three-coordinate CNC Machine Tools Based on EFAST Method

机床几何误差是影响机床加工精度的主要因素之一,本文针对机床几何误差建模、几何精度灵敏度分析、筛选关键几何误差等问题进行研究。结合多体系统理论和齐次坐标变换建立三坐标数控机床的几何误差模型,求解机床空间位置误差表达式。使用雷尼绍XL-80激光干涉仪对三坐标数控机床进行几何误差测量试验,将测量结果导入九线法误差辨识模型,辨识三坐标数控机床的21项几何误差。应用Simlab软件中的拓展傅里叶幅值灵敏度检验方法(EFAST)对三坐标数控机床的几何误差进行灵敏度分析,并筛选出影响三坐标数控机床加工精度的关键几何误差。此外,以关键几何误差为基础,建立三坐标数控机床的简化几何误差模型,与三坐标数控机床的几何误差模型进行对比分析。结果表明,该方法可合理经济地提高三坐标数控机床加工精度及几何误差补偿。

The geometric errors of machine tools is one of the main factors affecting the machining accuracy of machine tools.This paper focuses on the geometric errors modeling of machine tools,the sensitivity analysis of geometric accuracy,and the selection of key geometric errors.Based on the theory of multi-body system and homogeneous coordinate transformation,the geometric errors model of three-coordinate CNC machine tools is established,and the spatial position error expression of the machine tools is solved.The geometric errors of the three-coordinate CNC machine tools are measured with Renishaw XL-80 laser interferometer,and the measurement results are introduced into the nine line errors identification model to identify 21 geometric errors of the three-coordinate CNC machine tool.By using the Extended Fourier Amplitude Sensitivity Test(EFAST)in the Simlab software,the sensitivity analysis of the geometric errors of the three-coordinate CNC machine tools is carried out,and the key geometric errors affecting the accuracy of the three-coordinate CNC machine tools are screened out.In addition,based on the key geometric errors,a simplified geometric errors model of the three-coordinate CNC machine tools is established and compared with the geometric errors model of the three-coordinate CNC machine tools.The analysis results show that the method can reasonably and economically improve the machining accuracy and geometric errors compensation of three-coordinate CNC machine tools.