卧式加工中心关键几何误差元素甄别方法

A Methodology for Identifying Crucial Geometric Error Elements of Horizontal Machining Centers

以某卧式加工中心为研究对象,通过定义机床各部件局部坐标系间初始位置特征矩阵和初始位置误差特征矩阵,构建机床空间误差完备模型,解决传统建模方法中若干项几何误差元素缺失的问题。借助体对角线定位精度测量实验,对所建完备模型准确性进行验证,进而在此基础上提出几何误差元素实际参预度的概念及其计算方法,并由此形成基于空间误差完备模型和实际参预度的关键几何误差元素辨识新方法。分别根据计算所得实际参预度和灵敏度,对给定加工中心关键几何误差元素进行甄别。对比分析显示,相较于传统灵敏度分析,所提基于实际参预度的甄别方法具有更高的准确性。甄别结果表明,该加工中心关键几何误差元素有7项,且均与位置相关,与X轴进给相关的关键几何误差元素有4项,说明机床X轴运动组件制造精度可能存在较大缺陷。

Taking a horizontal machining center as the research object,a complete volumetric error model was established by defining the initial position and position error characteristic matrix for local coordinates of each components of machine tools,so as to solve the problems that some geometric error elements(GEE)were lost when concerning about the conventional volumetric error modeling methodology.The proposed complete volumetric model was experimentally validated by measuring the volumetric diagonal positioning errors.The concept,as well as the calculation approaches,of GEEs actual contribution factors(ACF)were presented on the basis of the complete volumetric error model.A novel methodology for identifying the crucial GEEs was furtherly formulated with the help of complete volumetric error model and ACF.Based on the calculated ACFs or sensitivities,the crucial GEEs of the given machining center were respectively identified.The comparative analyses show that the proposed identification methodology,fundamental of which is the concept of ACF,is more accurate and effective than that based on traditional sensitivities analyses.The identified results indicate that there are 7 crucial GEEs for the studied machining center,which are all position-dependent.In particular,4 elements of the crucial GEEs are related with feeding motions in X-axis,which suggests that the machine tool movable components in X-axis may have massive flaws affected the manufacturing accuracy.