数控机床几何误差相关性分析方法研究

Correlation Analysis of Geometric Error for CNC Machine Tool

摘要:

为提高数控机床的精度, 降低装配、制造过程产生的几何误差的影响，基于多体系统理论建立几何误差模型，在误差相关性分析的基础上，提出了一种辨识关键性几何误差元素的方法。首先，基于多体系统理论及齐次坐标变换方法建立了三轴数控机床几何误差模型，构建了几何误差元素相关性分析模型。其次，采用拉丁超立方抽样方法在整个参数空间内抽样，有效避免了单因素分析的缺陷。最后，通过计算拉丁立方抽样确定的误差元素引起的空间几何误差,进行相关性分析并辨识影响机床精度的关键几何误差元素。误差补偿后的圆测试对比结果表明,该方法可判别影响数控机床空间精度的重要误差元素,并能够定量辨识误差元素对几何误差向量的作用效果，可为机床误差补偿及精度分配提供重要的理论参考。

Abstract:

In order to improve the accuracy of NC machine tool and reduce the influence of geometric errors caused by assembly and manufacturing process, the geometric error model was established based on multi-body system theory, and a new method of identifying key elements of the geometric errors was proposed on the basis of geometric errors correlation analysis. Firstly, geometric errors model of three-axis vertical CNC machine tools was derivated by using multibody system theory and homogeneous coordinate transformation method, and correlation analysis model of the geometric error elements was established, which contained 21 geometric errors of three-axis NC machine tools. Secondly, to avoid the defects of single factor analysis, and considering the coupling effects of geometric error elements, Latin hypercube sampling method was used in the whole parameter space sampling. Finally, based on the geometric error model and correlation analysis model, spatial error was calculated by using geometric errors element which was determined by Latin cube sample. And the key geometric error elements that affected the accuracy of machine tool were analyzed. Before error compensation, the twelve-line method was applied to identify the geometric error elements for each axis based on Renishaw XL—80 laser interferometer measuring system. The comparison result of circular tests after error compensation showed that the method can effectively and quantificationally identify the key factors that affecting the precision of machine tool space and the effects of error elements of total space error, thus important theoretical foundation was provided for accuracy allocation and error compensation of machine tool reasonably.