Nouvelle analyse des phénomènes vibratoires en tournage

Abstract

Tél : 05 40 00 62 23 Résumé Dans le processus de fabrication par enlèvement de matière sur machinesoutils, l'apparition des vibrations est inévitable. Dans les situations où l'amplitude dépasse les limites de la précision dimensionnelle, le phénomène vibratoire est préjudiciable. L'étude expérimentale présentée ici permet d'identifier les principaux paramètres relatifs au comportement dynamique du système usinant. La localisation des déplacements de la pointe de l'outil dans un plan est démontrée grâce aux résultats expérimentaux. L'existence de ce plan et les corrélations avec les caractéristiques élastiques du système usinant permettent de simplifier le modèle dynamique 3D. Avec l'approche expérimentale réalisée, un modèle dynamique est proposé en concordance avec les résultats expérimentaux. Mots clés : vibrations / modèle expérimental / plan des déplacements / vibrations auto-entretenues AbstractIn the cutting process, machine-tools vibrations are generally a real problem when the amplitude crosses the limits of dimensional or surface quality workpiece precision required. It is necessary to develop models taking into account the threedimensional vibratory approach to control the vibrations phenomena. An experimental study has been realized to understand the behavior of the cutting system and to identify its vibrations properties. The displacement's localization of the tool in a spatial plan, showed by the experimental results, allows us to simplify the threedimensional dynamical model. In this study, the experimental approach is completely presented and the first points of the three dimensional vibratory model are proposed according to the experimental results. Keywords: vibrations / experimental model / displacement plan / auto-excited vibrations.

Link between Chips and Cutting Moments Evolution

“…Average torsor components measured at the tool tip point (ap=3.5 mm)The analysis of Table2and Table3confirms the following results obtained in[4]:…”

Displacements analysis of self-excited vibrations in turning

“…These frequencies are lower than those obtained ( [8]) during the machining system dynamic characterization with a no-cutting process, which are located at approximately 550 Hz (Fig. 3) [5]. The recorded frequencies, therefore, correspond well to the self-excited vibrations related to the cutting process.…”

Dynamic characterization of machining systems

“…The frequencies below 100 Hz, belong to the engine behaviour, the amplitudes are very weak, very low and appear on each tests configuration. The frequencies corresponding to no cutting process are given [6] for the three directions in the case of the kinematics chain "electric motor turning the spindle and advance movement coupled". The measured significant frequencies are into the domain of 230 Hz up to 1,000 Hz (see figure 24), and more, on the three x, y and z directions.…”