In-Process Analysis of Machine Tool Structure Dynamics and Prediction of Machining Chatter

Theoretical and experimental investigations were carried out to identify the dynamics of a machine tool structure during cutting to predict the borderline of stability against the self-excited regenerative chatter. The validity of theoretical analyses in calculating the stability limit for conventional machining was confirmed by cutting experiments using a structural model. The model dynamics were identified during cutting under stable (non-chattering) cutting conditions by applying a technique of system identification based on time series analysis of the small random cutting force variations measured by a specially designed tool dynamometer and the corresponding minute vibrations. The experimentally obtained borderline of stability had a fairly good agreement with that calculated from the identified dynamics of the structure and the cutting dynamics, the latter being estimated from the static cutting data based on the so-called shear plane model.