Basic Nonlinearity of Tool Chatter Vibration(Advanced machining technology)

Abstract

Tool chatter vibration is known as one of most complicated processes of machining because it is very difficult to explain and predict the dynamic behavior of tool chatter in time domain by not only linear theories but also nonlinear theories proposed so far. Hence, in this paper, non linearity of the damping coefficient of cutting tool in chatter vibration was investigated experimentally using restricted contact cutaway tools and a normal tool, which have one degree of freedom in the feed direction. Change in the damping coefficient during chatter was obtained from the Lissajous' figure, which showed the trajectories of chatter vibration in a two-dimensional space of the feed force and displacement in the feed direction, on the assumption that the energy balance of chatter was in quasi-steady state. As the result, it was found that the damping coefficient increased with amplitude of vibration at the beginning of chatter. However, when the amplitude increased to a certain value, the runout of the cutting tool occurred and the damping coefficient decreased.