机床—主轴耦合系统动力学建模与模型修正

复杂精密零件的加工对机床装备的性能不断提出新的挑战。为了保证零件加工精度,有必要在设计阶段对机床整机的动态特性进行精确预测和评估。以机床主轴系统为研究对象,介绍一种机床—主轴系统耦合动力学模型,并指出该模型中存在结合面动态特性参数的辨识问题。为了修正该耦合模型,提出一种基于频率响应函数的有限元模型修正技术。采用包含平动自由度(Degree of freedom,DOF),转动DOF以及平动与转动耦合DOF的刚度矩阵来描述结合面的动态特性,通过测量结合面处的动态响应数据,辨识出高速主轴与机床之间结合面的刚度参数,从而达到模型修正的目的。试验结果表明,修正后的机床—主轴耦合模型反映出了机床结构对主轴动态特性的影响,能较好地预测主轴安装到机床上以后的动态特性,从而为高性能机床的数字化设计与制造提供理论依据。

Dynamic Modeling and Model Updating of Coupled Systems between Machine Tool and Its Spindle

The machining of complex and precise parts continually brings new challenges to the performance of machine tools.To ensure the machining accuracy of parts,it’s necessary to predict the dynamic behavior of the whole machine tool in the design stage.Aimed at machine tool spindle systems,a coupling model between the spindle and machine tool is introduced and the existed problem of the joint dynamics identification in this model is also pointed out.In order to update this coupling model,a finite model updating technique based on frequency response function is proposed.The joint dynamics is modeled as a stiffness matrix which contains translational degree of freedom(DOF),rotational DOF and coupled DOF.Dynamic response data are measured to identify the joint dynamics between the spindle and machine tool and therefore the analytical model is updated.The experimental results show that the updated coupling model between the spindle and machine tool can reasonably reflect the effects of the machine tool structure on the spindle and predict dynamic properties of the spindle system after mounting,which can provide theoretical proofs for the digitalized design and manufacture of high performance machine tools.