Self-excited vibrations in turning: cutting moment analysis

This work aims at analyzing the moment effects at the tool tip point and at the central axis, in the framework of a turning process. A testing device in turning, including a six-component dynamometer, is used to measure the complete torsor of the cutting actions in the case of self-excited vibrations. Many results are obtained regarding the mechanical actions torsor. A confrontation of the moment components at the tool tip and at the central axis is carried out. It clearly appears that analyzing moments at the central axis avoids the disturbances induced by the transport of the moment of the mechanical actions resultant at the tool tip point. For instance, the order relation between the components of the forces is unic. Furthermore, the order relation between the moments components expressed at the tool tip point is also unic and the same one. But at the central axis, two different order relations regarding moments are conceivable. A modifictation in the rolling moment localization in the (y, z) plan is associated to these two order relations. Thus, the moments components at the central axis are particularly sensitive at the disturbances of machining, here the self-excited vibrations.