计电磁不平衡拉力的高速电主轴转子偏心特性研究

Dynamic characteristics of high-speed motorized spindles affected by rotor's eccentric mass

针对高速电主轴转子偏心状态产生的两种载荷-电磁不平衡拉力与离心力,据电磁理论建立电磁不平衡拉力载荷模型,理论分析两种偏心载荷幅值及频率特性;应用Timoshenko梁理论,建立耦合入轴承动态支撑刚度矩阵并以两种偏心载荷为外力的转子有限元模型;据动力学方程计算转子系统固有频率、振型,研究电磁不平衡拉力载荷与离心力载荷对转子系统动态特性影响;通过实验验证两种偏心载荷为引起高速电主轴转子振动的主要因素及转子系统一阶固有频率随转速升高而升高,实验结果与理论计算误差较小。

The rotor of high-speed motorized spindle with eccentric mass generates two kinds of loads： unbalanced magnetic pull and centrifugal force. Based on electromagnetic theory, an unbalanced magnetic pull model was developed. And the amplitude and frequency characteristics of two types of eccentric masses were also analyzed theoretically. A finite element model of the rotor using Timoshenko beam theory was established, which includes bearing stiffness matrix and the two types of eccentric masses. The natural frequency and vibration mode were calculated according to the rotor dynamical equations. The analysis of dynamic behaviors of the rotor affected by eccentric loads shows that the unbalanced magnetic pull and centrifugal force are the main excitation forces. An overall experiment on a motorized spindle was carried out under several operating conditions. The good agreement is achieved between the theoretical results and the experimental data. It is concluded that the two types of eccentric masses seriously influence dynamic characteristics of the rotor.