Ce travail de thèse se place dans le contexte des études d’accidents graves sur les réacteurs à neutrons rapides à caloporteur sodium. Dans le cadre de la démarche de conception et de sûreté, tous les types d’accidents doivent être étudiés afin d’assurer l’exhaustivité de l’analyse de sûreté, en traitant la variabilité des scénarios accidentels et en quantifiant les marges de sûreté. Pour cela, des outils physiques sont développés pour être couplés à des techniques avancées de statistique permettant de répondre rapidement et quantitativement aux questions relatives à la conception du réacteur vis-à-vis des conséquences d’un accident grave et de prendre en compte des incertitudes et de la variabilité des scénarios accidentels. La mise au point de l’outil physique OCARINa (Outil de Calcul analytique Rapide pour les Insertions de réactivité dans un RNR-Na) dédié à la phase primaire du transitoire d’insertion de réactivité non protégée UTOP (Unprotected Transient OverPower) a ainsi fait l’objet de cette thèse. Les travaux ont porté sur l’identification des phénomènes physiques prépondérants, leur modélisation (thermique et thermomécanique), et une contribution à la validation expérimentale et numérique. Enfin, une application de l’intérêt de cet outil a été réalisée à partir de deux études BEPU (Best-Estimate Plus Uncertainties). Elle a permis d’identifier les paramètres les plus influents sur la réponse de l’outil, et de quantifier leur impact vis-à-vis des résultats expérimentaux. / Within the framework of the Generation IV Sodium-cooled Fast Reactor R&D French program, a new physico-statistical approach is currently followed by the CEA for accident transient calculations in complement to the reference mechanistic codes. This approach involves a fast-running description of extended accident sequences coupling physical models for the main phenomena to advanced statistical analysis techniques. A large number of simulations may be performed in a reasonable computational time while describing all the possible bifurcations of the accident transient. In this context, this PhD work deals with the development (models and results assessment) of the physical tool dedicated to the primary phase of the Unprotected Transient OverPower accident called OCARINa (Outil de Calcul analytique Rapide pour les Insertions de réactivité dans un RNR-Na). The accident main phenomena, their modelling (thermal and thermomechanical models) and a contribution to the experimental and numerical validation are described. Finally a demonstration of BEPU studies has been done, resulting in the identification and the impact quantification of the more influent uncertain parameters on experimental results.

abstract: The demand for miniaturized components with feature sizes as small as tens of microns and tolerances as small as 0.1 microns is on the rise in the fields of aerospace, electronics, optics and biomedical engineering. Micromilling has proven to be a process capable of generating the required accuracy for these features and is an alternative to various non-mechanical micro-manufacturing processes which are limited in terms of cost and productivity, especially at the micro-meso scale. The micromilling process is on the surface, a miniaturized version of conventional milling, hence inheriting its benefits. However, the reduction in scale by a few magnitudes makes the process peculiar and unique; and the macro-scale theories have failed to successfully explain the micromilling process and its machining parameters. One such characteristic is the unpredictable nature of tool wear and breakage. There is a large cost benefit that can be realized by improving tool life. Workpiece rejection can also be reduced by successfully monitoring the condition of the tool to avoid issues. Many researchers have developed Tool Condition Monitoring and Tool Wear Modeling systems to address the issue of tool wear, and to obtain new knowledge. In this research, a tool wear modeling effort is undertaken with a new approach. A new tool wear signature is used for real-time data collection and modeling of tool wear. A theoretical correlation between the number of metal chips produced during machining and the condition of the tool is introduced. Experimentally, it is found that the number of chips produced drops with respect to the feedrate of the cutting process i.e. when the uncut chip thickness is below the theoretical minimum chip thickness. / Dissertation/Thesis / Masters Thesis Engineering 2015

Este trabalho avalia o uso de insertos autolubrificantes de pó de aço ferramenta sinterizado para aplicação em ferramentas dos processos de Conformação a Frio. São apresentadas a preparação e a análise de diferentes composições de misturas de pós de aço ferramenta H 13. A Metalurgia do Pó convencional foi utilizada como processo para a obtenção dos insertos do estudo. Foram compactadas e sinterizadas misturas de pó de aço H13 com a adição de percentuais variados do lubrificante sólido Bissulfeto de Molibdênio – MoS2, também em pó, com o objetivo de atribuir propriedades de autolubrificação ao composto. O percentual de lubrificante sólido empregado nas amostras variou de 1% a 5%, com posterior sinterização. Os resultados obtidos no Ensaio de Atrito com anéis de Alumínio AA6351 recozido apresentaram nos insertos autolubrificantes do estudo coeficientes de atrito μ entre 0,10 e 015, menores que os valores μ entre 0,20 e 0,30 obtidos com aço H13 laminado convencional. Também o desgaste abrasivo do ferramental proposto avaliado no Ensaio de Abrasão com Roda de Borracha foi 12% menor quando comparado com o aço ferramenta H13 laminado exposto ao mesmo ensaio. / This study evaluates the use of self-lubricating tool steel powder sintered inserts for use in tools of Cold Forming processes. Preparation and analysis of various compositions of H13 tool steel powder mixtures are presented. The conventional Powder Metallurgy was used as a process for obtaining the study inserts. Were compacted and sintered mixtures of H13 steel powder with the addition of varying percentages of the solid lubricant Molybdenum Disulphide - MoS2, also in powder form, with the purpose of giving self-lubricating properties to the composite. The percentage of solid lubricant used in the samples varied from 1% to 5%, with subsequent sintering. The results of the friction test on AA6351 aluminum rings had friction coefficients μ between 0.10 and 015 with self-lubricating inserts in study, smaller than μ values between 0.20 and 0.30 obtained with the conventional steel H13 laminate. Also, the abrasive wear of the tooling proposed evaluated in the abrasion test with rubber wheel was 12% lower when compared to the H13 tool steel laminate exposed to the same test.

Orientador: Anselmo Eduardo Diniz / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-08T23:12:33Z (GMT). No. of bitstreams: 1 Oliveira_AdilsonJosede_D.pdf: 5045036 bytes, checksum: f173982d932402dfe8a6935cdb29b638 (MD5) Previous issue date: 2007 / Resumo: Normalmente, os componentes dos moldes e matrizes responsáveis pela forma das peças manufaturadas têm complexas geometrias e são confeccionados em materiais de elevada dureza, o que torna a atividade de usinagem mais difícil. A utilização do Fresamento com Altas Velocidades tem sido um caminho para a usinagem destes componentes. Esta pesquisa tem como objetivo melhorar a compreensão do desempenho e dos mecanismos de desgaste das ferramentas no Fresamento com Altas Velocidades de aços endurecidos utilizados nos moldes e matrizes. Em operação de semi-acabamento, avaliou-se a utilização de fresas de topo toroidal de metal duro e de cermet em diferentes condições de fresamento no aço ABNT H13 com 50 HRC de dureza. Em operação de acabamento, avaliou-se a utilização de fresas de topo esférico de metal duro sólido e de pastilhas intercambiáveis montadas em porta-ferramentas de aço e de metal duro no fresamento do aço ABNT D2 com 61 HRC de dureza. Os principais resultados em operação de semi-acabamento demonstram que a utilização de ferramentas de metal duro com cobertura promove uma maior vida de ferramenta, a inclinação da parede usinada tem forte influência na vida da ferramenta e que o desgaste das ferramentas envolve diferentes mecanismos: no início da vida, principalmente a abrasão, a difusão e/ou ¿attrition¿; e no final da vida, as adesões e os microlascamentos. Em operação de acabamento, os resultados demonstram que a utilização de porta-ferramentas de metal duro proporciona os melhores resultados de vida de ferramenta quando comparada à utilização de porta-ferramentas de aço. Entretanto, os resultados de vida de ferramentas com a utilização de porta-ferramentas de metal duro são inferiores à utilização de fresas de metal duro sólido. O desgaste das ferramentas nas operações de acabamento foi caracterizado por adesões de material da peça na aresta de corte e por microlascamentos / Abstract: Usually, the die and moulds components, which are responsible for the part forms, have complex geometries and are made of high hardness materials, what cause difficulties for their machining. High Speed Milling has become an alternative for machining these components. This work aims to broaden the performance understanding and the wear mechanisms on tools used in High Speed Milling of hardened steels for dies and moulds. In semi-finishing operation, it was analyzed the use of cemented carbide and cermet tools in different cutting conditions in milling of ABNT H13 steel with 50 HRC of hardness. In finishing operation, it was analysed the use of ball nose solid tools of cemented carbide and indexable inserts assembled on steel and cemented carbide toolholder in milling of ABNT D2 steel with 61 HRC of hardness. The main results in semi-finishing operation showed that the use of coated cemented carbide tool exhibited longer life, the machined surface inclination has a strong influence on tool life, and the tool wear involves different mechanisms: in the beginning of tool life, mainly abrasion and diffusion and/or attrition, and in end of tool life, adhesions and micro chipping. In finishing operation, the results showed that the use of cemented carbide toolholder causes longer tool life than the use of steel toolholder. However, tool life using cemented carbide toolholder is shorter than the using solid tools of cemented carbide. The tool wear in finishing operation was characterized by adhesions of part material and by microchipping / Doutorado / Materiais e Processos de Fabricação / Doutor em Engenharia Mecânica

This dissertation concerns the application of a method for developing context dependent CASE-tool evaluation frameworks. Evaluation of CASE-tools prior to adoption is an important but complex issue; there are a number of reports in the literature of the unsuccessful adoption of CASE-tools. The reason for this is that the tools have often failed in meeting contextual expectations. The genuine interest and willingness among organisational stakeholder to participate in the study indicate that evaluation of CASE-tools is indeed a relevant problem, for which method support is scarce. To overcome these problems, a systematic approach to pre-evaluation has been suggested, in which contextual demands and expectations are elucidated before evaluating technology support. The proposed method has been successfully applied in a field study. This dissertation contains a report and reflections on its use in a specific organisational context. The application process rendered an evaluation framework, which accounts for demands and expectations covering the entire information systems development life cycle relevant to the given context. The method user found that method transfer was indeed feasible, both from method description to the analyst and further from the analyst to the organisational context. Also, since the span of the evaluation framework and the organisation to which the method was applied is considered to be large, this indicates that the method scales appropriately for large organisations.

There exist several methods, which can be used for evaluation of commercially available CASE-tools. Each method has its own focus and is based on specific underlying assumptions. There have been attempts to standardise evaluation of CASE-tools; however available methods differs much from each other. One such method, named the 2G method has been proposed, which for each application, will establish a specific evaluation framework. This framework is tailored to the organisation at a specific point in time (since an organisation will change over time). The method consists of two phases which are iterated a sufficient number of times before a stable evaluation framework will be the result. The 2G method has been successfully applied on several applications in different organisations, though only for evaluation of CASE-tools before adoption. In this dissertation we report on an application of the 2G method, which aims to evaluate a CASE-tool from a company context which has already adopted a CASE-tool. As part of this method application the 2G method has also been transferred to the organisation. An additional issue this dissertation addresses is what kind of support a general Qualitative Research Tool will offer a method user when using the tool in a 2G method application. Likewise the goal includes to establish is what is poorly or unsupported in such tool in a 2G application. This dissertation will show that the 2G method is applicable also in a scenario where a CASE-tool has already been adopted, and therefore demonstrate that the method also is useful in evaluation studies performed after a CASE-tool has been adopted in an organisation. From the experiences of the application points will be made concerning what kind of support one would like to have in a qualitative research tool to simplify the work during the 2G applications.

Les difficultés majeures rencontrées en production des pièces mécaniques métalliques sont dues aux conditions de chargements extrêmes appliqués lors de la mise en forme ainsi qu'au problème de l'usure prématurée des outils de coupe de coupe. Dans ce cadre, les travaux de thèse sont centrés sur la mise en évidence et la compréhension des mécanismes physiques mis en jeu lors de l'usure des outils de coupe depuis l'échelle de la microstructure jusqu'à celle du système usinant, en passant par l'échelle de la pointe de l'outil (échelle mésoscopique). A cet effet, Un modèle analytique permettant de décrire l'usure par abrasion et de prédire la durée de vie des outils a été développé sur la base d'une approche statistique rendant compte de l'hétérogénéité des particules pouvant être à l'origine de la dégradation de l'outil. La prise en compte de la nature du contact collant-glissant et de l'effet du coefficient de frottement via des résultats de la littérature couplés au modèle proposé ont permis de mettre en évidence l'influence des paramètres opératoires de la coupe des métaux sur le volume d'usure enlevé par abrasion. A la suite ce modèle a été confronté à des résultats expérimentaux préalablement réalisé dans le cadre de la coupe orthogonale. En parallèle une analyse inclusionnaire est réalisée pour l'identification et la quantification des inclusions non métallique jugées responsable de l'usure par abrasion. Les résultats obtenue via des observations MEB et microscopique ainsi que des traitements d'images a permis d'alimenter en données le modèle prédictif / Tool wear and tool failure are critical problems in the industrial manufacturing field since they affect the quality of the machined workpiece (unexpected surface finish or dimensional tolerance) and raise the production cost. Improving our knowledge of wear mechanisms and capabilities of wear prediction are therefore of great importance in machining. The three main wear modes usually identified at the tool/chip and the tool/workpiece interfaces are abrasion, adhesion and diffusion. Besides the fact that understanding mechanisms that govern these wear mechanisms are still incomplete, the experimental analysis is very difficult because friction interface features (such as temperature, pressure, particles embedded in the contact …) are not easily measurable. The objective of this research work is to understand the physical mechanisms governing the tool wear by taking into account the sensibilities to scale going from the microscopic scale (microstructure scale) to the macroscopic scale (scale of the manufacturing operation) passing by the mesoscopic scale (tool tip scale). For this purpose, an analytic wear model was developed to describe the abrasive wear and to predict the cutting tool life. The proposed model is based on a tribological approach including a statistical description of the distribution of particles seen as non-metallic inclusions. The latter are assumed embedded at the interface of contact and having a conical shape characterized by two main parameters in the present approach: the corresponding size and apex angle. The volume of the removed material per unit time is chosen in this study as the main parameter to describe the abrasive wear mode. Coupled with literature results, the developed model is able to take into account the nature of the sticking-sliding contact and the effect of the friction coefficient on the rake face of the cutting tool. In order to identify all the material's parameters of the predictive model, a study of non-metallic inclusion considered responsible of the abrasive wear was performed on the 42CD4 steel. The determination of inclusion type and inclusion morphology was assessed qualitatively and quantitatively through microscopic and MEB observations as well as image processing. Finally, the volume removed by abrasion given by the model was compared to the experimental results previously achieved under orthogonal cutting.

This master thesis deals with a design of technological process description for a mechanical engineering part called „pressure plate“. The component is analyzed in regards to its mechanical engineering design and used material. Some brief theoretical prerequisites for an effective solution of the problem are summarized in the paper. A detailed research of current technological methods is provided, together with an analysis of the State-of-the-Art in manufacturing, introduction of technological possibilities of the company and a timeline records of the manufacturing process. In regards to the current methods and technologies, changes to the technological process are applied. Among these changes is a unification of machinery used in the process. This leads to an innovation of the methodology and the ways to clamp the component. Other applied alternations focus on a stabilization of the drilling process, which is reached by a choice of new tools and adjustment of cutting parameters. Furthermore, a variable coding of tools in case of automatic tool change is designed. This paper then provides two possible solutions based on proposed changes and alternations. These solutions, together with the tools mentioned, are subjects to a techno-economical assessment.

Thesis evaluaes production of the body latch, which is used for window, window shutter and door locking. It is made from 11 375 steel sheet which is 1 mm thick. Annual production is 50000 pcs. Progresive cutting and drawing in one combined tool and finishing product in single opperation drawing tool was choosen as most effective. Single operation drawing will be operated manually. Tools was designed by series of technological callculations to which was projected presses Šmeral LDC 160 with additional devices. Acording to economic valuation, cost of production of one piece is 16,50 Kč and production becames profitable after production of 27185 pieces.

The diploma thesis deals with the analysis of the wear of tools fitted with cermet cutting edge. The first part is focused on the theoretical aspects of the problem, which are applied in the practical part. The aim was to perform cutting tests in which carbon steel was turned under selected cutting conditions. Tool wear during turning and the quality of the machined surface were monitored. Machining continued until the selected wear criterion reached the limit value. Two different cermets were tested and the measured data were the basis for the analysis of the wear of the tool edges and the determination of the tool life.