Variable Compliance-related Aspects of Chatter in Turning Thin-walled Tubular Parts

Thin tubular parts are often subject to turning process during manufacturing. The increasing compliance of the workpiece, which is associated to tool displacement and to matter removal, can give rise to chatter, leading to poor surface quality or premature machine/tool damage. The present work addresses an experimental case of turning a steel thin-walled tube featuring intense vibrations with variable parameters. Observations of transient records during the pass suggest a strong influence of the matter removal on the eigenfrequencies of the system, while the tool's motion implies strong variation of the modal projection of the cutting force. Another characteristic phenomenon is the intermittency of the vibrations and discontinuous chatter frequency evolution. These phenomena are reproduced and analyzed numerically. By means of a finite element modeling, the part's geometry variation during the pass is taken into account. Finally, a stability analysis is carried out for several states of this evolutive system in order to gather insight into the steady cutting conditions.