Analysis of vibration behavior of damped tool arbor by finite element method

Abstract

To improve cutting performance and suppress chatter vibration during machining of large mechanical parts with a long slender cutting tool, a design method was investigated for a tuned mass damper imbedded tool arbor. To clarify the effects of the dynamic stiffness and damping ratio of the weight which is supported at both ends inside the hollow space of the arbor on the dynamic compliance at the end of the arbor, finite element analysis was conducted. First, since the weight has twisting vibration in its 2nd order natural mode, it is necessary to consider 2 degrees of freedom of the motion to optimize the damper. Then, the relationship between the motion of the damper and damping performance is clarified in accordance with the change in spring constant of the weight. From the results, an area exists where there is little change in the maximum negative real part of the compliance due to the change in spring constant. Designing the spring constant in this area stabilizes the damping performance. Furthermore, comparison of the results of finite element analysis and the conventional particle model analysis revealed that the results of finite element analysis show a smaller real part of the compliance than those of particle model analysis. This is because the inertial forces of the weight are applied not to the end of the arbor but to the tool holder side of the arbor and the damping effect is smaller than that in the particle model.

Tuning vibration absorbers to mitigate simultaneous regenerative and mode-coupling chatter

“…This approach can be achieved by increasing the dynamic stiffness of the oscillating part through the addition of a vibration absorber. 22 A vibration absorber is a spring-mass component that is fitted to the primary body (the unstable part). The chatter mitigation is accomplished by substantial oscillation of the absorber's mass.…”