Enhancement of in-process identification for stable spindle rotation against chatter vibration with a time-domain milling simulator

In order to improve cutting accuracy and efficiency in milling, chatter stability analysis should be performed to find a stable cutting condition. However, the stability prediction has a difficulty to ensure high reliability, because modal parameters of a tool have to be identified accurately, which change with the spindle rotation. In this study, a novel approach for identification of stable spindle rotation against chatter is proposed by decreasing spindle rotation during chatter and capturing drastic shifts of chatter frequency with disturbance observer in the spindle control system. Furthermore, identification error is discussed with a time-domain milling simulator, and a theoretical compensation equation for the error is derived.