Self-excited vibrations in turning: cutting moment analysis

TL;DR

This study analyzes the effects of self-excited vibrations in turning by measuring cutting moments at the tool tip and central axis, revealing that central axis analysis better isolates true mechanical actions from disturbances.

Contribution

It introduces a method to analyze cutting moments at the central axis, reducing disturbance effects and providing clearer insights into self-excited vibrations during turning.

Findings

Moments at the central axis are less affected by vibrations.

Order relations of force components are consistent at the tool tip.

Two possible order relations for moments at the central axis are identified.

Abstract

This work aims at analysing 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 analysing 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 single. Furthermore, the order relation between the moments components expressed at the tool tip point is also single and the same one. But at the central axis, two different order relations regarding moments are conceivable. A modification in the rolling moment localization in the (y, z) tool 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.