Modeling Errors Influencing Active Structural Methods for Chatter Mitigation in Milling Process

A concept of active structural method dedicated to the mitigation of regenerative chatter in milling process is presented. This concept proposes an adaptronic high performance motor spindle integrating piezoelectric actuators and accelerometers combined with an optimal control strategy whose objective is to increase the productivity in chatter-free machining conditions. The control strategy, named stabilization, explicitly considers the cutting process in the controller synthesis in order to tailor the dynamics of the spindle according to the encountered machining conditions. As this strategy is based on models of machine tool, workpiece and process, modeling errors play a significant role and might corrupt the stability prediction and influence the performance of such active structural method. A series of machining tests illustrates the problematic and points out the difficulty to accurately and reliably predict the occurrence of chatter in milling process. It also indicates the current limitation of the proposed concept.