基于灵敏度筛选的机床多固定结合面等效刚度虚拟识别方法

A Virtual Identification Method for the Equivalent Stiffness of Multiple Fixed Connection Surfaces of Machine Tools Based on Sensitivity Screening

摘要: 针对缺少实验条件时机床多固定结合面刚度难以辨识的问题，本文以由床身、立柱、主轴箱、主轴、刀具、鞍部和工作台组成的七部件机床为研究对象，提出一种基于灵敏度筛选的等效刚度虚拟识别的方法。本文沿主传力路径选取床身–立柱、立柱–主轴箱、床身–鞍部和鞍部–工作台四个关键固定结合面。其中，高保真基准模型采用4点分布式三向弹簧来表征界面特性，低维识别模型采用集中等效三向平移刚度参数来进行描述。本文结合模态频率和刀尖–工作台相对位移响应对参数进行修正。结果表明，识别后的模型在低阶模态频率和主要共振响应方面与基准模型更加接近。由此可以看出，该方法能够较好表征关键结合面对整机动力学特性的主导作用。

Abstract: This paper addresses the problem of identifying the stiffness of multiple fixed joints in a machine tool when experimental conditions are limited. The study considers a seven-component machine tool made up of the bed, column, headstock, spindle, cutting tool, saddle, and worktable, and it presents a virtual identification method for equivalent joint stiffness based on sensitivity screening. Along the main load-transfer path, four key fixed interfaces are selected: the bed-column joint, the column-headstock joint, the bed-saddle joint, and the saddle-worktable joint. In the high-fidelity reference model, each interface is described by a four-point distributed spring system with stiffness in three directions. In the reduced-order identification model, each key interface is represented by lumped equivalent translational stiffness parameters in three orthogonal directions. The parameter updating process uses both modal frequencies and the relative displacement response between the tool tip and the worktable. The results show that, after identification, the reduced-order model agrees more closely with the reference model in low-order natural frequencies and major resonant responses. This result indicates that the proposed method can capture, in a clear and effective way, the dominant influence of key fixed joints on the overall dynamic behavior of the machine tool.