In the process of metal milling, especially in the machining of low?stiffness workpieces, chatter is a key factor affecting many aspects such as surface quality, machining efficiency and tool life. In order to avoid the chatter, a milling chatter recognition method based on dynamic and Wavelet Packet Decomposition(WPD) is proposed from the signal processing. The modal parameters of the system are obtained by modal experiments. Based on the principle that the chatter frequency will peak near the natural frequency of the system, the original milling force signal is decomposed by WPD, and the sub?signals containing rich chatter information are selected for signal reconstruction. Finally, the time?frequency and Hilbert spectrum characteristics of the reconstructed signal are compared and analysed, and the chatter recognition is performed. At last, the proposed method is verified by the experiments. The results demonstrate the effectiveness and reliability of the proposed method.

Grinding technology with minimum quantity lubrication technology is a new type of environmentally friendly and efficient processing technology. It has the characteristics of less cutting fluid and low cutting force, and is conducive to the maintenance of the tool and can effectively improve the quality of the workpiece. However, the cooling performance of the high?pressure air flow of the grinding technology with minimum quantity lubrication is very limited, which can not meet the need for cooling in the grinding zone. The traditional casting cooling technology can meet this demand by using a large amount of grinding fluid. In this paper, the research background, development status and latest achievements of micro?lubrication technology were reviewed, which lays a theoretical foundation for further study of the characteristics and principles of these special grinding technology with minimum quantity lubrication..