Chatter detection and suppression system integrated with the CNC lathe

Chatter vibrations lead to poor surface finish and tool wear. Reliable chatter detection is a prerequisite for its prevention. This paper presents a lathe spindle equipped with displacement sensors to detect chatter vibrations. The sensors are integrated into the machine tool through communication with the CNC control system and are protected from cutting fluids and chips. The data collected during machining are used to calculate the chatter indicator, which is based on the multiple samples per revolution method. The use of displacement sensors has made it possible to define an additional indicator that distinguishes between the appearance of chatter vibrations and the entry or exit of the workpiece. The transmissibility function is used to evaluate the vibration at the tool tip, which contributes to the autonomy of the chatter detection. Numerous experimental tests have confirmed the high reliability of the proposed indicators, which helps to avoid false alarms. When chatter vibrations are detected, an autonomous algorithm for regulating the spindle speed is activated. The stable speed is selected based on the natural frequency, which is determined using the experimentally estimated frequency of chatter vibrations. Cutting tests have confirmed the effectiveness of the algorithms developed.