Regenerative chatter reduction by active damping control

The objective of this paper is to demonstrate the effect of active damping on regenerative chatter instability for a turning operation. Two approaches are used for this purpose. In the first approach, the traditional stability analysis technique in Altintas [Manufacturing Automation, Cambridge University Press, Cambridge, 2000. [1]] and other works is adopted and a correlation between the chip shape (which is dependent on the spindle speed) and the system damping is presented. It is shown that different spindle speeds cause changes in the system damping, resulting in different levels of stability limits at different spindle speeds. A second approach involves plotting of the root locus of the system poles with increasing axial width of cut. This study presents a different perspective to the problem. It is shown that the low and high stability regions of the stability lobe diagram are due to different relative positions of the poles and zeros of the system. Active damping is proposed as a strategy to enhance the stability limits of the system. The effect of active damping is studied by the two approaches, mentioned above, both showing that active damping can Successfully enhance the stability limits, particularly in the low stability regions. (c) 2006 Elsevier Ltd. All rights reserved.