Milling stability prediction and adaptive chatter suppression considering helix angle and bending

Abstract

In milling process, chatter is one of the most unfavorable factors, which will reduce surface quality, limit tool life, accelerate tool wear, and decrease machining efficiency. To solve this problem, a great deal of research has been done in milling dynamic modeling and chatter suppression. In this paper, a new milling force calculation method considering helix angle and bending is presented, in which the instantaneous cutting area is calculated in an improved way. The milling dynamic equations are established based on the proposed model, and the stability limit is obtained with semi discretization method (SDM). Results show that tool bending and helix play important roles in stability lobe diagram (SLD). Subsequently, the stability prediction is verified in the milling experiment. Stability analysis can just provide the guidance for selection of milling parameters. In order to get higher efficiency and larger stable region, the time-domain least mean square (LMS) adaptive algorithm is constructed and implemented for chatter suppression in this article. For the sake of applying the method to experiments, the smart toolholder equipped with piezoelectric stack actuators is designed and mounted to a three-axis milling machine. The experimental results show that this method can suppress chatter effectively.