Self-Excited Chatter and its Marks in Turning

Abstract

Investigations were made on self-excited chatter of the work which is held at one end on a lathe machine. Analysis was carried out by a two-degrees-of-freedom system. It was verified that introduction of the multiple regenerative effect governs the finite amplitude of the vibration after it is excited. It was also shown that behavior of the work displacement rotating around the origin during the vibration could be explained by taking into account a resistive force which is inversely proportional to the cutting speed and is proportional to the velocity of the vibration. Phase difference of the vibration occurring for each turn of the work was measured by making use of a microcomputer system. Correlation of the pattern left on the work with the phase difference and with the multiple regenerative effect was studied. A slight change of the vibration frequency varies the pattern even though the phase difference is kept constant. This was also demonstrated by a simulation which generated the pattern of surface shape.