Active Control of Regenerative Chatter in Turning by Compensating the Variable Cutting Force

Abstract

During metal cutting operations performed by conventional machine tools (turning, milling…) often appear vibrations due to the emergence of a variable force generated by the so-called regenerative effect. Such vibrations, known as regenerative chatter, may not be prevented at the machine design stage and often limit productivity severely. Therefore, a lot of effort has been put into developing solutions for this problem in the past. To compare the performance of such solutions, it is interesting to realistically reproduce in the laboratory the mentioned regenerative effect in a reliable, repeatable way and covering general machining conditions. With this objective, the paper presents an improvement of a Hardware-in-the-loop chatter simulator that creates this type of vibration for turning machines on a specifically designed mechanical structure. This simulator completely corrects the effects that the delay, introduced by the used equipment (by actuator and controller, mainly), has on the vibration and, moreover, it is capable of imposing general behaviors for any machine with a certain damping factor. Later, by installing inertial actuators on the mentioned structure, the operation of various active chatter control systems may be compared. In this work, the effort made to accurately create the variable machining force is harnessed to try its compensation, by generating with the inertial actuator an approximately inverse control action. In this context, the performance of the novel controller, based on the cancelation of the whole variable cutting force, is analyzed.