螺旋铣孔主轴单元的动态特性分析

Dynamic characteristics analysis of the helical milling spindle unit

螺旋铣孔加工过程中,刀具在自转的基础上公转并保持轴向进给,是适合于航空工业典型难加工材料的先进制孔工艺技术。根据螺旋铣孔的加工原理设计了螺旋铣孔专用主轴单元,其典型特征为三转子、双偏心结构及具有类似于行星轮系的自转公转系统。对修改的整体传递矩阵方法建立该主轴单元的动态模型进行研究,分析了主轴单元的固有频率特性,并通过有限元软件进行了验证。采用灵敏度方法对影响主轴动态特性的设计参数进行了分析。结果显示,轴承跨距、轴承刚度及单元总长度对于主轴单元的动态特性有显著影响。

Helical milling is a hole-making technique, in which the cutting tool orbits around the axis of the hole while spinning on its own axis and feeds in the axial direction. It is an advanced hole-making technique aiming at difficult-to-cut materials in the aerospace industry. Based on the principles of helical milling process, special spindle unit was designed. The typical characteristics of spindle unit are three-rotor, double-eccentricity and rotation with revolution like as planetary gear system. Dynamic model of the helical milling spindle unit based on the modified whole transt^r matrix method is established. Then the natural frequencies received were verified by ANSYS. Dynamics analysis based on the sensitivity of the structure parameters is conducted to identify main factors. The results indicate that the bearing span, bearing stiffness and total length of unit are sensitive to the dynamic behaviors.