基于敏感度分析的机床关键性几何误差源识别方法

零部件几何误差耦合而成的机床空间误差是影响其加工精度的主要原因,如何确定各零部件几何误差对加工精度的影响程度从而经济合理地分配机床零部件的几何精度是目前机床设计所面临的一个难题。基于多体系统理论,在敏感度分析的基础上提出一种识别关键性几何误差源参数的新方法。以一台四轴精密卧式加工中心为例,基于多体系统理论构建加工中心的精度模型,并利用矩阵微分法建立四轴数控机床误差敏感度分析的数学模型,通过计算与分析误差敏感度系数,最终识别出影响机床加工精度的关键性几何误差。计算和试验分析表明,该方法可以有效地识别出对机床综合空间误差影响较大的主要零部件几何误差因素,从而为合理经济地提高机床的精度提供重要的理论依据。

An Identification Approach for Key Geometric Error Sources of Machine Tool Based on Sensitivity Analysis

The volumetric error coupled by geometric errors of parts is the main reason affecting the machining accuracy.How to determine the influence degree on the processing precision generated by the geometric errors of parts,thus distribute the geometric errors of parts economically and reasonably,is currently a difficult problem of machine tool design.Based on the theory of multi-body system and sensitivity analysis,a new method of identifying the key geometric error sources parameters is proposed.Taking a four-axis precision horizontal machining center as example,the precision model of the machine center is built up with the theory of multi-body system,thus a mathematical model for error sensitivity analysis of four-axis computer numerical control machine tools is established with matrix differential method,finally the key geometric error sources which affect the machining precision are identified after sensitivity coefficient of error are calculated and analyzed.Calculation and example show that geometric error factors of major parts that have relatively significant influence on comprehensive spatial error of the machine tools can be identified effectively,thus important theoretical basis is provided for improving precision of machine tools reasonably and economically.