考虑刀柄接触状态的高速主轴双转子系统动态特性仿真

Dynamic characteristics simulation of coupled double-rotor system considering contact condition of tool holder

为揭示刀柄—主轴结合面接触状况对高速主轴系统动态特性的影响,在考虑其接触应力和刚度动态变化的基础上,基于阻抗子结构耦合法建立了主轴—拉杆双转子动力学模型,并对拉杆拉力和动态夹紧力分别对结合面刚度特性的影响,以及对应的刚度变化对双转子系统频率特性的改变进行了仿真。结果表明,初始拉紧力和动态夹紧力都能提高结合面刚度,且动态夹紧力的提升程度更大,但高速时的刚度特性却由刀柄和主轴的相对离心膨胀量之差决定,呈下降趋势;考虑拉杆时主轴系统的频率显著降低,说明拉杆为一薄弱点;小幅变化的拉紧力对系统频率特性影响不大,说明该数量级的拉紧力已足够高,且主轴频率对刀柄—主轴结合面的刚度变化并不敏感。

To reveal the influence of tool holder-spindle joint surface＇s contact condition on dynamic characteristics of high speed spindle system, a double-rotor dynamic model was established based on receptance coupling method by considering the dynamic changes of contact force and contact stiffness. Simulations of contact stiffness characteris- tics and frequency changes of double-rotor system were taken out under the influence of initial and/or dynamic draw- bar force. The result showed that contact stiffness could be raised by increasing initial and dynamic drawbar force, and dynamic drawbar force was more efficient, but the contact characteristics in high speed condition disputed down- ward trend which determined by the difference value of centrifugal expansion of tool holder and spindle. The modal frequencies decreased remarkably when drawbar was considered, which meant the drawbar was a weak point. Small changes of draw force could not affect frequencies characteristics significantly, which indicated the force of this mag- nitude was big enough and the frequencies were not sensitive to the changes of contact stiffness.