Displacement difference feedback control of chatter in milling processes

Chatter is an unfavorable phenomenon that commonly occurs in the machining process, which results in various problems such as poorly finished surfaces, short tool life, and low machining efficiency. Thus, based on the intelligent manufacturing paradigm, an active chatter control strategy is proposed in this work. Different from the commonly used control methods, which strive to reduce the whole vibration (i.e., stable and chatter vibrations) during the machining process, the proposed strategy focuses on suppressing the chatter component by feeding back the displacement difference of the spindle-tool system at the current time and one tooth passing period before. On the basis of the proposed chatter control concept, a piezoelectric actuator-based active chatter control intelligent spindle-tool system as well as a proportional-differential (PD) controller and a fuzzy controller are designed to perform numerical simulations and milling experiments with different cutting parameters. The results prove that the developed strategies not only successfully control chatter and increase the maximum material removal rate (MRR) but also significantly decrease the required voltage of the actuator, which is conducive to saving control energy.