Modal and Twist Stiffness Analysis about Direct-drive Bi-Rotary Milling Head

Bi-rotary milling head is the core component of a 5-axis CNC milling machine, modal and twist stiffness analysis is needed in its design process. Vibration characteristic of direct drive A/C bi-rotary milling head is been analyzed by finite element method (FEM), former four order vibration modes of the milling's structure are given. The influence of the swing angle of the A-axis to the natural frequency of the milling head is analyzed. The natural frequencies when the milling head is working are interval values, the first order natural frequency is [120.48, 122.91], the second order natural frequency is [139.68, 142.08], the third order natural frequency is [328.68, 331.9], the fourth order natural frequency is [369.68, 372.45]. The twist stiffness that varies with operating state is computed. This computing provides technological support for design and improvement of this type of milling head.