Adaptive inverse control of chatter vibrations in internal turning operations

Abstract

In this article, adaptive inverse control of chatter vibrations in internal turning process is<br><br>addressed. The active boring bar is composed of a slender steel cutting tool, an electrodynamic<br><br>shaker as controllable actuator and an IEPE accelerometer as feedback sensor. The<br><br>SISO control system actuates in the direction normal to the cut surface. A novel adaptive<br><br>inverse control algorithm is presented in this paper. This algorithm is mainly used in the<br><br>feed-forward Active Noise Control (ANC) applications and is known as the Filtered-x<br><br>Normalized Least Mean Square (FxNLMS). In order to extend the application of adaptive<br><br>inverse control algorithms in the field of Active Vibration Control (AVC), the FxNLMS algorithm<br><br>with feedback architecture is suggested for the specific problem of chatter suppression<br><br>in internal turning operations.<br><br>The performance of developed adaptive feedback controller is experimentally verified<br><br>during the internal turning of Aluminum alloy 6063-T6. The value of critical limiting depth<br><br>of cut is anticipated to be nearly 0.2 [mm] for the slender boring bar. However, the stable<br><br>cutting process is conducted by the active boring bar in the presence of adaptive controller<br><br>up to depth of cut 2 [mm]. That is, the boundary of stability is enhanced by at least 10 folds.<br><br>It has been observed that the amplitude of chatter vibrations is efficiently suppressed adjacent<br><br>to the fundamental resonance peak of the active boring bar. In addition, the feedback<br><br>FxNLMS controller effectively attenuates the boring bar’s vibration by at least 70 dBs.<br><br>Moreover, the periodic chatter marks are eliminated from the surface texture of workpiece<br><br>and the roughness of cut surface is remarkably improved. The obtained results suggest that<br><br>the practical application of adaptive inverse control algorithms for chatter rejection can be<br><br>extended to other machining processes as well.