高转速下主轴-刀柄结合部接触刚度分析

Contact stiffness analysis of spindle-toolholder system with high speed

提出一种宏微观相结合的方法建立高转速下主轴-刀柄系统结合部接触刚度模型.宏观上假设主轴-刀柄结合面为理想圆锥面,通过有限元方法获得不同转速下锥形表面的接触压强分布;微观上假设接触表面由微凸体构成,并基于接触压强采用考虑域拓展因子影响的三维分形模型计算锥形结合部的接触刚度.以BT40刀柄为研究对象,其无转速工况下主轴-刀柄系统理论预测与实验频响函数一致性较好,在此基础上分析转速及拉刀力对结合部刚度影响规律,确定了转速极限值为1.5×10^4 r/min,拉刀力合理取值范围为[8,12]kN,研究结果为主轴-刀柄系统的结构优化及应用提供理论基础.

A method combining macro and micro was proposed to built the contact stiffness model of spindle-toolholder joint at high speed.In macro analysis,the spindle-toolholder joint surface was assumed as ideal taper,the contact pressure distribution of taper surface was obtained by using the finite element method.In micro analysis,the contact surface was composed of many asperities,and based on the contact pressure distribution,the three-dimensional fractal model,considering the influence of expand coefficient,was adapted to compute the contact stiffness of taper joint.The BT40 toolholder as the research object was built,and the consistency of the theoretical prediction and experimenal results at zero speed about the frequency response function was good.Based on the method,the relationship of the total contact stiffness and the working speed or drawbar force was revealed.The limit speed was determined as 1.5×10^4 r/min and the reasonable range of drawbar force was obtained as[8,12]kN.The research results could be a theoretical basis for the structural optimization of the spindletoolholder and the application.