Method of controlling chatter in a machine tool

摘要

A method of controlling chatter in a rotating, chip cutting machine tool cutting at a predetermined depth on a workpiece in which the speed of rotation of the cutting tool relative to the workpiece and the rate of speed of the cutting tool relative to the workpiece both adjustably controlled between predetermined minimum and maximum rates for the particular combination of machine tool and workpiece material. The method includes the steps of detecting vibration signals representative of relative vibrations between the machine tool and the workpiece and generated by preliminary operation of the machine tool at predetermined conditions, processing that generated signal as a function of signal frequency, obtaining a signal indicative of the rotational speed and determinating the threshold of the signal level above which are excluded harmonics of the predetermined rotational frequencies that are indicative of chatter in the cutting tool. Additional steps interrupt the feed of the cutting tool and change the speed of rotation if operationally generated audio signal levels exceed a threshold and then change the speed of rotation of the cutting tool and resume the feed of cutting engagement. These steps are repeated until operation of the machine tool is obtained without operationally generated chatter signals exceeding the threshold or, when necessary, reducing the speed of rotation and the rate of feed to predetermined levels known to avoid generation of chatter signals in excess of the threshold.