机床关键几何误差元素辨识及其公差设计方法

Methodology of Identifications and Tolerance Design of Machine Tools Crucial Geometric Error Elements

面向加工精度指标提出机床关键几何误差元素辨识及其公差设计方法。以某型立式加工中心为对象,基于螺旋理论对机床空间误差进行建模;结合所得机床空间误差模型及加工精度指标定义,推导建立加工精度评估模型,同时提出间接试验验证策略及实施技术;通过正交实验、统计学对影响加工精度的关键几何误差元素进行辨识,并利用数值试验对辨识结果进行验证,并基于响应面法构建加工精度与关键几何误差元素的映射关系,由此将后者的公差设计转换为一类优化问题;利用遗传算法获取各关键几何误差元素最优公差,在加工精度指标满足要求的同时,机床产品成本达到最低,表明所提方法有利于实现机床精度稳健设计。

Facing the machining accuracies,a methodology of identifications and tolerance design of machine tools crucial geometric error elements(CGEE)is proposed.Taking a vertical machining center as the object,the volumetric error of machine tools is modeled based on screw theory.Combined with the volumetric error model and the definitions of machining accuracies,the machining accuracies evaluation models are established,and the indirect experimental verification strategies and implementation technologies are proposed.The CGEE can be identified by orthogonal experiment and statistical analysis,and the identification results are verified by numerical experiment.Then,the mapping relationship between machining accuracies and CGEE is constructed based on response surface method,and the tolerance design of the latter is transformed into an optimization problem.Genetic algorithm is used to obtain the optimal tolerance of CGEE.While the machining accuracies meet the requirements,the product cost of machine tool is the lowest,which shows that the proposed method is conducive to the robust design of machine tools accuracies.