超高速磨削机床主轴系统模态分析

针对液体动静压轴承支撑的超高速磨削主轴系统工作的特殊性,在机床工作过程中,主轴高速旋转,动静压轴承的支撑刚度随转速动态变化.为了解主轴系统工作过程中的动态特性,应用Flunent软件求解液体动静压轴承的动态支撑刚 度,而后在此基础上利用有限元分析软件ANSYS建立超高速磨床主轴系统的三维有限元模型,并对其进行模态分析,得到了各阶固有频率和振型.通过设置不同转速下轴承的支撑刚度,获得主轴系统模态分析结果,并利用图解法求解出主轴系统的临界转速.分析结果表明主轴系统在高速旋转状态下,系统的结构刚度会发生变化,使主轴系统的固有频率改变,并且随着转速提高差异越显著.通过振动试验测试验证仿真分析的可靠性,经分析可知,试验与仿真的误差主要来源于支撑模型的简化.

Modal Analysis of Spindle System on Ultra-high Speed Grinder

Spindle system on ultra-high speed grinding supported by liquid hybrid bearing is special.In the process of machine working,spindle rotates in high speeds,and the supporting stiffness of hybrid bearing changes dynamically with the change of rotation speed of spindle.In order to understand the dynamic characteristics of the spindle system,Flunent is used to calculate the dynamic stiffness of the liquid hybrid bearing.The 3D finite element model of spindle system on ultra-high speed grinder is established,and the natural frequencies and mode shapes are obtained by utilizing ANSYS.Through setting different stiffness in different rotational speeds,the results of dynamic modal analysis are obtained,and the critical speeds of the spindle system are obtained through graphical method.The results show that in high speed rotation state,the centrifugal stiffening effect occurs due to the changes in structural stiffness of the system.With the rise of rotational speeds the differences become more significant.The simulation analysis is verified to be reliable through vibration experiment.the errors between experiment and simulation mainly come from the simplification for support model.