Président du jury Degrez, Gérard
Promoteur Delchambre, Alain
;Lambert, Pierre Publication Non publié, 2008-02-21
| Résumé : | Micro-assembly is of crucial importance in industry nowadays. Nevertheless, currently applied processes require improvements. Indeed, when dealing with the assembly of submillimetric components, usually neglected surface forces disturb the manipulation task. They are responsible for the component sticking to the gripper, because of downscaling laws. A promising strategy to tackle adhesion consists in working without contact. The present dissertation is focused on contactless handling with acoustic levitation. The advantages of contactless handling, the physical principles suitable for levitation and their applications are detailed. The opportunity for new handling strategies are shown. Acoustic levitation appears as the most fitted principle for micro-assembly. The elements to model acoustic forces are analysed and performances of existing modellings are assessed. A general numerical model of acoustic forces is implemented and theoretically validated with literature benchmarks. A fully automated modular levitator prototype is designed and used to experimentally validate the implemented numerical model. Specific instrumentations and protocols are developed for the acoustic force measurements. The numerical model is finally applied to the real levitator. Modelling results are used to support experimental observations: the optimisation of the levitator resonance, the influence of the reflector shape, the dynamical study of the component oscillations, the stability with lateral centring forces and rotation torques, the component insertion and extraction from the levitator, the effect of pressure harmonics on the acoustic forces, and the manipulation of non spherical components. Acoustic forces are experimentally measured and a very good agreement with the modellings is obtained. Consequently, the implemented simulation tool can successfully be applied to a complex manipulation task with a component of any shape in a real levitator. |
