Etude du comportement dynamique des outils toriques en usinage 5 axes

The use of toroidal tools rather than ball-end tools for the machining of complex surfaces has several advantages. The main lies in a smaller variation of the effective cutting speed during the evolution of the lead angle of the tool compared to surface. The problem of very low (even null) cutting speed on the central part of the tool is eliminated. However, dynamic problems remain during the cutting process, in particular during machinings with tools whose ratio diameter over length is small. Indeed, the choice of the milling strategy has an important influence on the behavior of the tool and thus on the result obtained on the part from the dimensional and surface quality points of view. The purpose of our study is to better understand the behavior of low diameters toroidal tools during the machining of complex surfaces.Ttheoretical and experimental approaches were coupled. The theoretical study attempts to determine the relation between the strategy used and the dynamic behavior of the tool during machining. The aim of the experimental part was to analyze the dynamic behavior of the tool during machining for various milling strategies. For that, acoustic analyses, as well as dimensional and surface qualities measurements were carried out. That enables us to define rules for the choice of machining trajectories on complex surfaces with this type of tools. Indeed, some strategies are prejudicial for the machining quality and for tool life, whereas others offer a real improvement on the machined part quality.