电火花机床主轴头的模态分析与减振设计

Modal Analysis and Vibration Reduction Design on an EDM Machine Tool Spindle

针对某机床厂生产的SH50电火花机床在实际工作中主轴头振动较大的问题,通过实验测试和有限元仿真相结合的方法,分析了主轴头的模态特性,并通过测试主轴头的工作振型(operating deflection shapes,简称ODS),找出了主轴头实际工作中的薄弱环节。理论模态、实验模态和ODS三种结果相互印证,增加了有限元模型的可信度,并以此模型为基础对主轴头进行了减振设计。模态实验中改进了传统模态实验依靠经验选取测点或均匀布点时,对经验高度依赖且实验效率较低的弊端,采用有效独立法和模态置信度(modal assurance criterion,简称MAC)矩阵相结合的方法,实验前先进行测点优化,然后根据优化结果布置传感器和力锤位置,提高了模态实验的精度和效率。结果显示,在主轴头结构上增加一个背板,能够提高主轴头频率,远离工作频率的共振范围,起到减振的目的。

For the spindle vibration during working process of the SH50 electrical discharge machining(EDM)machine tool,the modal characteristics of the spindle combining theoretical analysis with experimental verification are studied.First,the finite element model is built in ANSYS Workbench,and the theoretical modal of the spindle is analyzed.Further,the weak links in the spindle are found out during working process by testing its operating deflection shapes(ODS).Then,based on the effective independence method and modal assurance criterion(MAC)matrix,the sensor placements of key parts are optimized before modal experiment.After that,the modal and ODS tests are carried out on the spindle head according to the result of sensor placements optimization.At last,some advices on spindle vibration reduction are put forward after confirming the theoretical model by the experimental results.The simulation result shows that adding a backboard can greatly reduce the vibration of the spindle.