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International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / In the past few years, GPS has proven itself as an effective source of time space position information (TSPI) data for air vehicles. Currently, GPS truth systems are used to track aircraft ranging from low dynamic vehicles to high dynamic fighters. However, low-cost GPS TSPI instrumentation is not currently available for stores and weapons delivered by air vehicles. To date, data is collected by tracking dropped items using radar or optical means. This process is costly and time consuming. The purpose of this project is to leverage the recent advances in micro-electromechanical systems (MEMS) technology to develop a subminiature, inexpensive, low power, disposable telemetrytransmitting package. The purpose of this transmitting package is to up-link the GPS positional data from the weapon or store to the host aircraft. This data is then retransmitted by the host aircraft to a ground station and/or recorded on board for post processing. The transmission of the data to the host aircraft can provide near real- time position data for the released object. The transmitting package must have a unique identification method for application in tracking multiple objects. Since most of the systems used in weapons testing will be destroyed, it is extremely important to keep the development and maintenance cost low. In addition, the package must be non-intrusive to avoid any significant modification to the weapon and to facilitate quick instrumentation of the weapon for test and evaluation.

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In this study, the new predictive model for the micro-grinding process was developed by consolidating mechanical and thermal effects within the single grit interaction model at microscale material removal. The size effect of micro-machining was also included in the proposed model. In order to assess thermal effects, the heat partition ratio was experimentally calibrated and compared with the prediction of the Hahn model. Then, on the basis of this predictive model, a comparison between experimental data and analytical predictions was conducted in view of the overall micro-grinding forces in the x and y directions. Although there are deviations in the predicted micro-grinding forces at low depths of cut, these differences are reduced as the depth of cut increases. On the other hand, the optimization of micro machine tools was performed on the basis of the proposed design strategy. Individual mathematical modeling of key parameters such as volumetric error, machine working space, and static, thermal, and dynamic stiffness were conducted and supplemented with experimental analysis using a hammer impact test. These computations yield the optimal size of miniaturized machine tools with the technical information of other parameters.

Le procédé du micro-fraisage apporte de nombreux avantages pour la fabrication de pièces de petites dimensions. Les objectifs de cette thèse sont d'étudier les mécanismes physiques intervenant en micro-fraisage pour l'amélioration de la fabrication de produits miniaturisés. Plusieurs thématiques de recherche sont abordés afin d'améliorer la technologie de micro-usinage tant en terme de qualité que de productivité. Parmi ces thématiques, on peut citer le développement de micro-machines-outils, l'étude de l'influence de la microstructure des pièces, l'étude des trajectoires de l'extrémité de la micro-fraise, l'analyse numérique et analytique de la formation d'un copeau segmenté, la modélisation de la rugosité de la surface usinée, par exemple par réseau de neurones ou la conception de bancs d'essais. Certains résultats importants obtenus durant ce travail sont : 1. Les différences de phases métalliques dans un matériau polycristallin multiphase affectent beaucoup le processus de micro-fraisage, induisant des variations dans les efforts de coupe et influençant la qualité de la surface générée. 2. Pendant le processus de micro-fraisage, seule un seule arête coupe la matière. L'angle de l'arête de la direction d'avance sont les paramètres les plus importants pour réduire l'erreur d'usinage et pour répartir les efforts de coupe. 3. Le mécanisme de formation du copeau est étudié par une méthode hybride analytique-numérique. Les variations de la longueur de contact entre l'outil et le copeau et de la longueur de la bande de cisaillement sont les raisons principales qui expliquent l'apparition du copeau segmenté / Micromilling technique brings many advantages to the fabrication of micro-sized features. The objectives of this thesis are to investigate the micromilling mechanism for the efficient fabrication of miniaturized products. There are a number of issues that influence micromilling processes : cutting forces, dynamics and stability, chip formation, and machine tools. Several research topics, including Micro Machine Tool (MMT) development, workpiece microstructure influences, micromill tip trajectory investigation, wavy chip formation analysis via FEM-analytical ap- proach, surface roughness prediction based on the neural network and design of experiment are focused in this thesis. Some important results are listed : 1. The metal phase differences in the multi-phase polycrystalline material affect the micromilling process greatly, induce the cutting force variation, and influence the surface generation. 2. The single flute cutting condition always occurs in the micromilling process. The flute angle and feed angle are important to the machining error and chip load distribution. 3. The wavy chip formation mechanism is studied via hybrid analytical-FEM approach. It has been found the chip acquires additional angular acceleration in the segment generation instant. The variations of the tool chip contact length and shear band length are the main reasons of wavy chip segment formation

科学研究費補助金 研究種目:基盤研究(C) 課題番号:17560095 研究代表者:森 敏彦 研究期間:2005-2006年度