轴承座安装不同心时电主轴临界转速的计算

Calculation of critical speed of motorized spindle when bearing housing is installed with different cores

考虑实际装配中会因产生误差导致前后轴承座安装不同心。针对此工况,对电主轴进行动态特性分析。简化主轴系统,建立转子动力学模型并推导出转子系统的振动方程,得出该振动方程的特征方程。分析轴承-转子系统的刚度与质量矩阵,以求解该特征方程,最终计算出该条件下转子系统的临界转速。结果表明:安装轴承座不同心导致转轴倾斜的角度越大,其临界转速越小。主轴转速为10 kr/min,同轴度从3μm升至18μm(倾斜角为0.005 2°),其一阶、二阶、三阶临界转速分别下降了3.59%、1.77%、0.86%;对其进行ANSYS仿真分析,验证计算结果。

It is considered that errors may occur in actual assembly and lead to the installation of different cores of bearing housing.In view of this working condition,the dynamic characteristics of motorized spindle were analyzed.The rotor dynamics model was established and the vibration equation of the rotor system was derived.The characteristic equation of the vibration equation was obtained.The stiffness and mass matrix of the bearing-rotor system were analyzed to solve the characteristic equation,the eigenvalue was calculated,and finally the critical speed of the rotor system under the condition was calculated.By calculation,the greater the angle of inclination of the rotating shaft due to the concentric installation of the bearing housing,the smaller the critical speed.The spindle speed is 10 kr/min,the coaxiality is increased from 3μm to 18μm(inclination angle is 0.0052°),and the first,second and third order critical speeds are decreased by 3.59%,1.77%and 0.86%respectively;ANSYS simulation analysis was performed to verify the calculation result.