O presente trabalho visa apresentar informações que viabilizem a fabricação de componentes de rolamentos com limites superiores de resistência à fadiga, com a intenção de proporcionar uma vida útil maior ao rolamento, e, também, a otimização da fabricação das peças, dispensando em alguns casos o processo final e usual de retificação, o que implica uma redução de custos. As motivações deste estudo são a geração de altas tensões residuais compressivas no torneamento duro-seco a altas velocidades, a aplicação do RMB como técnica de medição das tensões residuais em aço 100CrMn6 e a otimização da qualidade/custos na fabricação de rolamentos. Para atingir essas metas, será estudada a influência dos parâmetros da usinagem (velocidade de corte (Vc), avanço (a), penetração (p) e desgaste da ferramenta (VB)) na geração das tensões residuais superficiais (sR) e sobre as forças de torneamento (Fc, Fa, Fp), em anéis internos de rolamentos cônicos de aço DIN 100CrMn6 endurecidos termicamente, procurando-se estabelecer uma correlação entre o desgaste da ferramenta e os referidos esforços e tensões residuais. Na etapa experimental, será utilizado um planejamento fatorial completo para executar os ensaios e medições projetadas. No ensaio de torneamento, serão medidas as forças de corte utilizando-se, para isso, um dinamômetro piezoelétrico. Em seguida, serão efetuadas medições de rugosidade. Também será realizado o estudo da microestrutura através da análise metalográfica. As tensões residuais serão medidas utilizando-se o método do furo-cego com extensometria elétrica, e as medidas das alterações microestruturais superficiais serão realizadas pela técnica do Ruído Magnético de Barkhausen (RMB). Serão correlacionados os valores de tensão residual obtidos pela técnica do furo com o RMB. / The present work presents information for the manufacturing of ball bearings components with higher limits of resistance to fatigue, enabling a longer useful life and also the optimization of the production of the pieces, making the usual and final process of grinding unnecessary, which would result in a costs reduction. The motivations of this study are the generation of compressive high residual stress in the hard-dry turning at high speeds, the application of the MBN as technique of measurement of the residual stress in steel 100CrMn6, and the optimization of the quality/costs in the manufacturing of ball bearings. In order to achieve these purpose, the work will study the influence of the machining parameters (cutting speed (Vc), feed rate (a), depth of cut (p), and wear of tool (VB)) in the generation of the superficial residual tensions and also the turning forces (Fc, Fa, Fp), in internal conical rings of ball bearings of steel 100CrMn6 thermally hardened, seeking to find a correlation between the stress of the tool and the referred efforts. In the experimental phase, a complete factorial planning will be used to perform the tests and measurements projected. In the turning tests, the cutting forces will be measured using a piezoelectric dynamometer. After that, measurements of superficial roughness will be performed. Also, the study of the microstructure will be made through the metallographic analysis. The residual tensions will be measured using the strain gage hole-drilling method and the measurement of the superficial microestrutural alterations will be carried out using the technical of the magnetic Barkhausen noise (MBN). The values of residual tension obtained by the hole-drilling will be correlated with the RMB.

Neste trabalho foram realizadas otimizações no processo de fabricação de micro cavidades na superfície do aço DIN 16MnCr5, com o objetivo de reduzir o coeficiente de atrito dinâmico entre duas superfícies. Para a confecção das micro cavidades (dimples) foi utilizado um laser com pulsos ultracurtos, de largura temporal de algumas dezenas de femtossegundos. Além de estudos de variação de fluência do laser, também foi analisado o resultado da utilização de diferentes perfis de energia do feixe. Para a caracterização das micro cavidades, foram utilizadas técnicas como a microscopia eletrônica de varredura, para análise morfológica, interferometria de luz branca e microscopia confocal para análise topográfica, dimensional e perfilométrica. Foram realizados ensaios de desgaste, em tribômetro para análise da variação do coeficiente de atrito após a texturização. Após os ensaios, percebeu-se que a texturização com pulsos ultracurtos apresenta grande vantagem na confecção de micro cavidades devido a precisão e ausência de interação térmica entre o laser e o material. Em relação ao atrito, as amostras texturizadas apresentaram redução da força e do coeficiente de atrito, porém, foram observados sinais de aumento da pressão de contato entre as superfícies. / In this work, optimizations were realized in the dimples manufacturing process on DIN 16MnCr5 steel surface, the target were to reduce the coefficient of dynamic friction between two surfaces. A laser with ultrashort pulses, temporal width of a few tens of femtoseconds, was used to manufacture dimples. In addition to studies of variation of laser beam fluency, the results of the use of different beam energy profiles were also analyzed. For analysis of dimples, techniques such as scanning electron microscopy (SEM), for morphological analysis, white light interferometry and confocal surface microscopy were used for topographic, dimensional and perfilometry. Wear tests were performed to analyze the variation of the friction coefficient in texturing surface. After the tests, it was observed that the texturing with ultrashort pulses presents a great advantage in manufacturing of dimples, due to the precision and absence of thermal interaction between the laser beam and the material. In relation to the friction coefficient, the textured samples presented a reduction of the friction force and consequently of the friction coefficient, but an increase in the contact pressure between the studied surfaces was observed.

The objectives of Sensor Based Fixture Design and Verification (SFDV) research are to provide the means for detecting contact failure of the workpiece with fixture locators and for preventing incorrect loading of the workpiece in a fixture. The fixtures that involve complex free-form surfaces especially in the aerospace industries face problems caused by the contact failure of the workpiece with locators. In batch and mass production defects often occur due to incorrect loading of the workpiece in a fixture by an operator due to fatigue or inadvertence. The current fixturing research is focussed on improving the fixture quality and other aspects and do not address these issues. This research is focussed on three areas, to generate algorithms for automatically foolproofing the fixtures, to build locators with embedded sensors that could be used to verify the contact and foolproof the existing fixtures, and to design and experimentally validate fixtures for free-form surfaces with sensors to verify the location. In foolproofing, workpieces were classified into different categories to identify the existence of a solution and the geometry was simplified and used to search for a solution based on symmetry/asymmetry to discover a foolproofing location. The algorithms were implemented in a CAD software and the solutions were verified in 3D space. The locators with inbuilt sensors were designed for foolproofing and location verification purposes and the sensors were used in case studies to establish credibility. A sensor based fixture design method is created for the part location of free-form surfaces using fiber optic sensors. An experimental fixture with sensors incorporated in the locators was used to determine the effects of surface curvature on the sensitivity of the sensors. A new theory on best locations for the sensor based locators by utilizing surface curvature is proposed based on the experimental results. The SFDV implementation may help realize the dream for any manufacturing sys­tem aspiring to move beyond the six sigma levels of quality and achieve zero defects.

O fresamento do aço inoxidável austenítico é um processo importante para a produção de peças em que se deseja alta resistência mecânica e à corrosão. No entanto, a usinagem desse material representa um desafio por suas características adversas ao corte. A alta taxa de encruamento e a alta dureza relativa fazem-no resistente ao corte, podendo gerar vibrações em diferentes faixas de frequência. Uma técnica importante ao processamento de sinais de vibração é a Transformada de Wavelet que permite analisar diferentes frequências do sinal através da subdivisão em aproximações e detalhamentos. Neste trabalho analisaram-se vibrações em alta e baixa frequência geradas no fresamento frontal do aço inoxidável austenítico AISI 316 a partir de sinais de força, coletados por meio de um dinamômetro piezelétrico e processados via Transformada de Wavelet Discreta. Também se fez a investigação dos perfis de rugosidade, dos parâmetros de rugosidade média (Ra) e média parcial (Rz) e das ondulações gerados na superfície fresada. Nos ensaios, foram utilizados insertos com três raios de ponta distintos, hastes da fresa com três diferentes comprimentos em balanço e foram variadas a rotação do eixo-árvore e a profundidade de corte axial em três níveis cada, totalizando 81 combinações de parâmetros. Constatou-se que a profundidade de corte representou a maior influência na vibração. Na usinagem com rotações abaixo do valor mínimo recomendado pelo fabricante (1600 rpm), houve dificuldades na formação e remoção do cavaco. A modificação do raio de ponta influenciou mais a vibração em pequenas profundidades de corte ou em zonas próximas às condições de instabilidade. O comprimento da haste mostrou comportamentos diferentes para a vibração, podendo estar relacionado com a mudança das frequências naturais do sistema e também pode definir entrada em regime instável. Verificou-se correlação do detalhamento (D1) da força resultante (vibração em altas frequências) com o parâmetro Ra para condições de vibrações intensas (maiores amplitudes), mas em regime estável. Assim, o parâmetro D1 pode ser utilizado na detecção de vibrações chatter no processo de fresamento frontal do aço inoxidável AISI 316. / The milling of austenitic stainless steel is important process for the production of part that require mechanical and corrosion resistance. However, the machining of this steel represents a challenge by its adverse features. The high hardening rate and the high relative hardness make it resistant to cutting and can generate vibrations in different frequency ranges. An important technique for the processing of vibration signals is the Wavelet Transform that allows the analysis of different signal frequencies through the subdivisions into approximations and details. In this work, high and low frequency vibration generated in end milling of AISI 316 stainless steel were analyzed from force signals collected through a piezoelectric dynamometer and processed via Wavelet Discrete Transform. Besides, the roughness profiles were investigated, as well as average (Ra) and partial mean (Rz) roughness parameters, and waviness generated on the milled surface. Three different insert nose radius, end mill tool lengths, depths of cut and spindle speeds were used in the experiments, totaling 81 combinations of parameters. It was found that depth of cut represented the greatest influence on vibration. In end milling with spindle speed below the minimum recommended by the tool manufacturer (1600 rpm) it occurred difficulties in the chip formation and removal. The modification of tool nose radius greater influenced the vibration at small depths of cut or in regions close to the stability limit. The end mill tool length showed different behaviors for the vibration, which may be related to the change of natural frequencies of the mechanical system and may also define an unstable state. The correlation of detail (D1) of the resulting force (vibration at high frequencies) with the parameter Ra for intense vibration conditions (larger amplitudes) was verified, but in stable state. Thus, D1 can be used for detecting chatter in end milling process of AISI 316 stainless steel.

L’amélioration des performances des détecteurs (au niveau de la résolution en énergie et de la résolution spatiale) pour la radiographie X médicale par l’utilisation d’un semi-conducteur montre l’intérêt de remplacer les détecteurs à base de cristaux scintillateurs (majorité des systèmes commerciaux) par un détecteur à base de semi-conducteur. Avec une perspective de respect environnemental, ces travaux portent sur le développement d’une nouvelle génération de détecteurs à base de semi-conducteur, différent du CdTe, pour l’imagerie médicale de rayons X fonctionnant en mode comptage, ce qui permet la réduction de la dose de rayonnement envoyée sur le patient. Deux axes de recherches en découlent, avec le choix d’un nouveau matériau semi-conducteur, le GaAs semi-isolant et d’une nouvelle géométrie de détection, la géométrie 3D.Ces travaux ont consisté à évaluer expérimentalement le semi-conducteur, afin de choisir un matériau (fournisseur, croissance) et une électrode métallique qui ont la capacité de compter des photons. Puis, la structure de détection, au travers de caractérisations des procédés technologiques nécessaires pour la réalisation de la géométrie 3D (usinage des électrodes, dépôt des électrodes, connexion à un circuit électronique) et de la validation du concept avec un dispositif de test, a été également étudiée. Enfin, les premiers résultats d’un détecteur 3D à base de GaAs semi-isolant, montrant la concrétisation de ces objectifs, sont proposés. / In X-ray medical imaging, semi-conductors tend to replace scintillator crystals (most of the commercial devices), thank to their higher spatial resolution and energy resolution. Counting mode is another tendency, because it allows reducing the radiation dose delivered to the patient. This work aims at developing a new generation of semi-conductor detectors, different from CdTe / CdZnTe for environmental concerns, and associated with a new detection structure (3D geometry). Semi-insulating GaAs from specific growth and supplier, with adapted metallic electrodes, shows the ability to count photons. Then, a proof of concept of the 3D geometry is provided, through the characterization of electrodes machining in bulk material, metal deposition and connection to a read-out electronic circuit. Finally, the achievement of these objectives is reflected in the preliminary characterization of 3D detector based on semi-insulating GaAs.

L'utilisation des structures sandwichs composées d’âme en nid d'abeilles et de peaux a considérablement augmenté ces dernières années dans plusieurs secteurs industriels tels que l’aéronautique, l’aérospatiale, le navale et l’automobile. Cet intérêt croissant pour ces matériaux alvéolaires est principalement lié à leur faible densité et meilleur rapport masse/rigidité/résistance en comparaison avec les alliages métalliques ou les matériaux composites classiques. Cependant, leur constitution rend souvent les opérations de mise en forme par usinage compliquées et difficile à mener à cause de l’usure prématurée des outils coupants et l’endommagement important induit en subsurface des pièces. En effet, les vibrations importantes des parois minces du nid d’abeilles sont une source de plusieurs problèmes comme la mauvaise qualité des surfaces usinées, les fibres non coupées, délaminage, défauts, etc. Les travaux de cette thèse s’intéressent à la compréhension du comportement des structures nids d’abeilles composite (Nomex®) et métallique (aluminium) en usinage. L’enlèvement de matière par fraisage présente pour ces matériaux plusieurs verrous scientifiques et technologiques. Une analyse expérimentale a permis d’identifier dans un premier temps les phénomènes physiques mis en jeu lors de la formation des copeaux et les interactions entre les arêtes de coupe et les parois minces des cellules de la structure alvéolaire. Un intérêt particulier a été porté sur la caractérisation des défauts induits dans le matériau par les différentes parties composant la fraise, le déchiqueteur et le coteau. Deux protocoles expérimentaux ont été mis en place afin de qualifier la qualité et l’intégrité des surfaces usinées. Ils tiennent compte de la particularité des âmes en nid d'abeilles : composite ou métallique, leur géométrie alvéolaire, leur densité et l’épaisseur fine des parois. Un nouveau critère de qualité a été établi et proposé en tant qu’indicateur d’endommagement pour le suivi de l’état des surfaces alvéolaires fraichement usinées. Basée sur l’analyse statistique de Taguchi, une hiérarchisation des paramètres d’usinage et leur influence sur le comportement de ces matériaux ont été ensuite réalisées. Par ailleurs, l’usure des outils de coupe a été étudiée selon le couple outil-matériau usiné et les conditions de fraisage choisies. Comme l’a montré l’étude expérimentale, l’optimisation des paramètres d’usinage via une approche expérimentale seule est souvent longue et coûteuse. La simulation numérique peut apporter une aide complémentaire et constituer un outil intéressant pour l’analyse de la physique de la coupe des nids d’abeilles. Dans cette optique et en deuxième partie de la thèse, un modèle numérique par éléments finis a été spécifiquement développé pour la simulation du fraisage 3D des matériaux nids d’abeilles. Pour le Nomex®, deux lois de comportement mécanique couplées avec l’endommagement ont été identifiées et implémentées via la subroutine VUMAT dans Abaqus explicit. Pour simuler la formation des copeaux, deux critères de rupture (Hashin et Tsai-Wu) avec chute de rigidité ont été exploités. Les résultats du calcul numérique et ceux des essais expérimentaux ont montré une bonne concordance en termes de mécanismes de formation des copeaux, d’efforts de coupe et de modes d’endommagement / The use of sandwich structures made with honeycomb core and skins has considerably increased these last years in several industrial sectors such as aeronautics, aerospace, naval and automotive. This growing interest for the alveolar materials is mainly related to their low density and better mass/stiffness/strength ratio compared to metal alloys or conventional composites. However, their constitution makes machining operations complicated and difficult to control because of the premature cutting tool wear and the significant damage induced in the workpiece. In fact, the important vibrations of the thin honeycomb walls are a source of several problems such as the poor surface quality, uncut fibers, delamination, defects, etc. This work deals with the understanding of the honeycomb composites behavior and metallic during machining. The material removal process by milling of these materials presents several scientific and technological challenges. Firstly, an experimental analysis has been used to identify the physical phenomena involved during the chip formation process and generated by the interactions between the cutting edge and the honeycomb cell walls. A particular interest was focused on the characterization of defects induced in the material by different parts of the cutter, the shredder and the saw blade. Two experimental protocols have been set up to qualify the quality and integrity of the machined surface. They consider the particularity of the honeycomb cores: composite or metallic, their geometry, and the thin wall thickness. A new quality criterion has been established and proposed as a damage indicator to monitoring the machining process and choice optimal cutting conditions. Based on Taguchi's statistical analysis, a hierarchy of the machining parameters and their influence on the behavior of these materials have then realized. In addition, the wear of cutting tools has been studied according to the selected tool-material couple and milling conditions. The optimization of machining parameters is often long and expensive only via experimental approach. Modelling and numerical simulation can provide complementary support with an interesting numerical tool to analyze the physics of cutting honeycombs. In this perspective and in the second part of the PhD thesis, a finite element numerical model has been especially developed for the 3D milling operation. For Nomex®, two coupled mechanical-damage behavior laws have been identified and implemented in Abaqus explicit subroutine VUMAT. To simulate the chip formation process and induced subsurface damage, two fracture criteria (Hashin and Tsai-Wu) with stiffness degradation concept have been operated. The comparison between the numerical simulation results and experimental data shows a good agreement in terms of the chip formation mechanisms, cutting forces and damage modes

Le travail proposé s’inscrit dans le contexte général de la maîtrise des propriétés des matériaux en relation avec les conditions d’usinage. Cette étude s'intéresse en particulier aux relations entre Microstructure et Usinage. La problématique développée dans ce travail concerne la mise en forme des alliages cuivre-béryllium à usinabilité améliorée (C17300) qui ont la réputation d’être versatiles à l'usinage, en dépit de propriétés mécaniques macroscopiques comparables. La mise en évidence de ces variations d'usinabilité et la recherche des causes et des solutions est l'objectif principal. Après la description du matériau d'étude et des méthodes de caractérisation, l'usinage des alliages C17300 est conduit en réalisant le suivi des efforts et des températures au cours d'une opération de coupe orthogonale stricte. Les résultats expérimentaux, à la fois de la caractérisation multi-échelle et de l'usinage des nuances industrielles dans un état de livraison et de remise en solution, sont présentés. Ils permettent de mettre en œuvre et de valider un modèle analytique de coupe. La question de l'influence de l'usinage sur la microstructure de la pièce usinée est complétée par le développement d'alliages modèles à dureté contrôlée élaborés en interne. Une caractérisation très précise de ces alliages (en surface, en sous-surface et dans les copeaux) permet d’évaluer l’impact de la microstructure initiale sur leur usinabilité. Enfin, une discussion confronte l'ensemble des résultats obtenus. Grâce à l'utilisation du modèle analytique validé, des informations essentielles (temps de contact, temps de transit et température au sein des bandes de cisaillement) permettent de mettre en évidence des phénomènes diffusionnels en cours d'usinage. L'adaptation de différents modèles de diffusion assistée permet d'expliquer les phénomènes observés. Pour clôturer l'étude, de nouveaux chemins de mise en forme des C17300 sont proposés, afin d'assurer l'obtention de propriétés mécaniques excellentes avec une usinabilité améliorée / The document presented hereby study the relationship existing between machining and materials behaviors, especially from a microstructure's perspective. The main purpose of this study is to understand the variability of cutting process of copper-beryllium alloys with improved machining capabilities, despite the fact that their macroscopic mechanical properties are even. After a description of those alloys and the characterization methods used in the present work, the machining of different materials are presented. The stresses and temperatures reached during orthogonal cutting are recorded and will describe the machinability. Experimental results of machining alloys which are in different metallurgical states are then presented. Those results will help the implementation of an analytical model of chips formation. The influence of machining process on work pieces and chips produced by orthogonal cutting of copper-beryllium alloys are then completed by a study of model materials developed in this work. Those alloys presenting well defined microstructure still possess the same hardness despite different thermo-mechanical treatments including mechanical deformation and ageing. A very detailed microstructure analysis of those model materials shows the influence of initial microstructure on their machinability. Diffusion mechanisms are put in light thanks to the information delivered by the analytical model (interaction time, transit time and temperature obtained through the different shear bands). Those assisted diffusion mechanisms explain the material behaviour during the orthogonal cutting. At last, better ways of material forming are exposed in order to have simultaneously excellent mechanical properties and excellent machinability for copper-beryllium alloys

Esta tese teve por objetivo desenvolver um algoritmo preciso e robusto capaz de compensar os erros térmicos volumétricos de um centro de usinagem 5 eixos em diferentes condições operacionais. O comportamento térmico da máquina foi modelado usando técnicas do método dos elementos finitos (MEF) com base na teoria do calor de atrito e calor de convecção, e validadas através dos vários campos de temperatura obtidos experimentalmente usando termopares e imagens térmicas. Os principais subsistemas da máquina foram inicialmente modelados, como o conjunto de fusos de esferas, guias lineares e motofuso, o que permitiu posteriormente a validação do comportamento termoelástico da máquina completa para onze ciclos de trabalho em vazio, seis ciclos de usinagem, nove ciclos de posicionamento e dois ciclos com temperatura ambiente variando, obtendo erros máximos inferiores a 9%, ao comparar os resultados numéricos com os resultados experimentais. A validação do modelo em elementos finitos permitiu usar os resultados obtidos para treinar e validar uma rede neural artificial (RNA) para prever os erros térmicos do centro de usinagem. Os desvios entre os erros térmicos previstos pela RNA e os calculados pelo MEF foram inferiores a 5%. Baseado nos resultados obtidos pelas medições das peças de trabalho usinadas foi possível formular e implementar um modelo de compensação dos erros térmicos no CNC do centro de usinagem, que obteve uma redução dos erros entre 62% e 100% nas peças usinadas com compensação. Foi também proposto um algoritmo de previsão e compensação dos erros térmicos para o centro de usinagem, baseado em todos os ciclos e simulações realizadas, e que se comparando com os resultados experimentais mostrou-se capaz de reduzir os erros térmicos entre 50% e 95%. Após sua validação, foi possível concluir que o algoritmo desenvolvido é uma ferramenta precisa e robusta para compensar os erros térmicos da máquina para várias condições de trabalho, podendo compensá-los mesmo com esta movendo-se a diferentes velocidades, em usinagem ou mesmo operando em temperatura ambiente variável. / This thesis aims to develop an accurate and robust algorithm capable of compensating the volumetric thermal errors of a 5-axis machining center under different operating conditions. The thermal behavior of the machine was first modeled using finite element method (FEM) techniques based on theory of friction heat and convection heat, and validated with the various experimentally raised temperature fields using thermocouples and thermal imaging. The main machine subsystems were initially modeled, such as the ball screw system, linear guides and spindle, which allowed for validating of the thermoelastic behavior of the entire machine for eleven no load duty cycles, six cycles of machining, nine cycles of positioning and two cycles with varying ambient temperature, obtaining errors lower than 9%, when comparing the numerical results with the experimental results. The validation of the finite element model allowed for the use of the results obtained to train and validate an artificial neural network (ANN) for predicting the thermal errors of the machining center. The deviations between the thermal errors predicted by ANN and the FEM simulation results were less than 5%. Based on the results obtained by the measurements of the machined workpieces, it was possible to formulate and implement a model of compensation of the thermal errors in the CNC of the machining center, which obtained a reduction of errors of 62% and 100% of the machined parts with compensation. It was also proposed a thermal error prediction and compensation algorithm for the machining center, based on all cycles and simulations performed, and that, comparing with the experimental results, it was able to reduce the thermal errors between 50% and 95%. After its validation, it was possible to conclude that the developed algorithm is an accurate and robust tool to compensate the thermal errors of the machine for various duty conditions, being able to compensate the errors even when it is moving at different speeds, in machining process or even operating in variable ambient temperature.

Orientador: Paulo Roberto de Aguiar / Banca: Amauri Hassui / Banca: José Alfredo Covolan Ulson / Resumo: O mercado, de maneira geral, vem exigindo níveis de quantidade cada vez maiores e redução de custos operacionais. Dentro desse contexto, as indústrias buscam processos mais automatizados e robustos, visando padronização nas operações e redução dos desperdícios. O controle eficaz o processo de fabricação é chave para atender às crescentes exigências do mercado. A utilização de redes neurais artificiais para o controle de processos complexos, com inúmeras variáveis, é um método que vem ganhando destaque acadêmico ao longo dos anos. O processo de furação para instalação de prendedores em estruturas aeronáuticas é um processo especial, no qual são exigidos controle rigorosos de qualidade devido aos requisitos de projeto, sendo, em muitos casos, mais importante a qualidade da furação, do que a vida útil da ferramenta. Este trabalho tem por objetivo apresentar um método para predição de diâmetros médicos e rugosidade de furos realizados durante o processo de furação de ligas aeronáuticas por meio de brocas helicoidais. Com a utilização de um sistema multi sensores acoplados a uma fresadora extrairam-se sinais, potência do motor elétrico, emissão acústica, vibração e forças de usinagem que alimentaram uma primeira rede neural artificial feedforward que teve a função de estimar a rugosidade e o diâmetro médio do furo. Uma vez de posse do valor estimado, ele servia de entrada em uma segunda rede neural "time delay" - TDNN que atuou na predição da rugosidade e diâmetro médio do próximo furo a ser realizado, mesmo antes de esse ser realizado mecanicamente. Posteriormente, buscou-se o mesmo procedimento previamente descrito, porém utilizando apenas apenas os sinais de potência e força no eixo Z como entrada da rede neural de estimação. Todos os valores preditos apresentaram erros pequenos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The market, in general, is demanding high levels of quality and reduction of the operational costs. The majority of companies has been searching for processes even more automatic and robust, aiming to standardize operations and reduce wastage. The effective control of the manufacturing process is the key for the growing market demands. The use of artificial neural networks for the control of complex processes, with many variables, has been drawing attention over the last years. The drilling process for fastenes installation in aircraft structures is a special process which requires a rigorous quality control due to the design requirements and, in may cases; the most important characteristic is the quality of hole. This work aims to present a method for prediction of diameter and surface roughness of holes performed in aeronautic alloys with carbide drill bit. Using a multi sensory system connected to a milling machine, signals were extracted (electric power, acoustic emission, vibration, cutting forces) and fed up into artificial neural network "feedforward" that had the function of estimating the surface roughness and the final diameters of the holes. The estimated values were used as inputs to a time delay neural network (TDNN) that acted in the prediction of the surface roughness and the final diameter of the next hole carried through, even before this hole was performed. Also, only the electrical motor power and force in Z axis were used as inputs to the first artificial neural network. All predicted values showed small errors when compared to the actual and the estimated values, the method was able to... (Complete abstract click electronic access below) / Mestre

Le terme "usinage à porte fermée", fréquemment employé par les PME de l’aéronautique et de l’automobile, désigne l’automatisation sécurisée du processus d’usinage des pièces mécaniques. Dans le cadre de notre travail, nous nous focalisons sur la vérification du montage d’usinage, avant de lancer la phase d’usinage proprement dite. Nous proposons une solution sans contact, basée sur la vision monoculaire (une caméra), permettant de reconnaitre automatiquement les éléments du montage (brut à usiner, pions de positionnement, tiges de fixation,etc.), de vérifier que leur implantation réelle (réalisée par l’opérateur) est conforme au modèle 3D numérique de montage souhaité (modèle CAO), afin de prévenir tout risque de collision avec l’outil d’usinage. / In High Speed Machining it is of key importance to avoid any collision between the machining tool and the machining setup. If the machining setup has not been assembled correctly by the operator and is not conform to the 3D CAD model sent to the machining unit, such collisions can occur. We have developed a vision system, that utilizes a single camera, to automatically check the conformity of the actual machining setup within the desired 3D CAD model, before launching the machining operation. First, we propose a configuration of the camera within the machining setup to ensure a best acquisition of the scene. In the aim to segmente the image in regions of interest, e.g. regions of the clamping elements and piece, based-on 3D CAD model, we realise a matching between graphes, theorical and real graphe computed from theorical image of 3D-CAD model and real image given by real camera. The graphs are constructed from a simple feature, such as circles and lines, that are manely present in the machining setup. In the aim to define the regions of interest (ROI) in real image within ROI given by 3D CAD model, we project a 3D CAD model in the real image, e.g. augmented reality. To automatically check the accordance between every region defined, we propose to compute three parametres, such as skeleton to represente the form, edges to represent a geometry and Area to represent dimension. We compute a score of accordance between three parameters that will be analyzed in fuzzy system to get a decision of conformity of the clamping element within it definition given in the CAD model. Some cases of machining setup configurations require 3D information to test the trajectory of the machine tool. To get out this situation, we have proposed a new depth from defocus based-method to compute a depth map of the scene. Finally, we present the result of our solution and we show the feasibility and robustness of the proposed solution in differents case of machining setup.