The countermeasure against forced and regenerative chatter in end milling process with multiple dynamic absorbers

Abstract

The present study investigates the effect of multiple dynamic absorbers on both forced chatter and regenerative chatter. The stability lobe of regenerative chatter is widely employed to find the axial depth of cut and the spindle speed in which regenerative chatter doesn't occur. However, the cutting force variation by the intermittent cutting with an end milling tool causes the forced chatter. The excitation frequency is determined by the spindle rotation frequency and the number of teeth. When the integral multiple of the excitation frequency approaches to the natural frequency of the tool and spindle system, resonance can be caused by the forced chatter. It is known that the resonance occurs in the spindle speed resistant to regenerative chatter. Therefore, it is important to take a countermeasure against not just the regenerative chatter but also the resonance caused by the forced chatter. In the present study, the cutting conditions which can lead to the regenerative chatter and the resonance are investigated by the direct numerical integration method. It is shown that an improvement in the regenerative chatter-free axial depth of cut can be obtained using the absorbers. Furthermore it is made clear that the absorbers have a significant suppression effect on not only the regenerative chatter but also the forced chatter.