Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-10-09T19:25:02Z No. of bitstreams: 1 kellyoliveiradoamaral.pdf: 690402 bytes, checksum: 02a13f617ac774ee60200d796a881dcd (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-10-09T20:03:50Z (GMT) No. of bitstreams: 1 kellyoliveiradoamaral.pdf: 690402 bytes, checksum: 02a13f617ac774ee60200d796a881dcd (MD5) / Made available in DSpace on 2017-10-09T20:03:50Z (GMT). No. of bitstreams: 1 kellyoliveiradoamaral.pdf: 690402 bytes, checksum: 02a13f617ac774ee60200d796a881dcd (MD5) Previous issue date: 2017-02-20 / As operárias de formigas cortadeiras coletam fragmentos vegetais frescos, os quais são utilizados como substrato para o cultivo do fungo simbionte. A dieta alimentar das operárias de formigas cortadeiras, sobretudo da prole, consiste no consumo do fungo simbionte, o que torna o forrageamento uma atividade primordial para o sucesso de suas colônias. Desse modo, a massa do fragmento vegetal transportado a colônia está diretamente relacionada ao sucesso do forrageamento, pois esta interfere na velocidade de deslocamento das operárias e no aporte de alimento para a colônia. Buscando identificar os fatores que podem modular a determinação da carga transportada em formigas cortadeiras, foi avaliado como o feromônio de trilha influencia na determinação do fragmento vegetal transportado por operárias de Acromyrmex subterraneus. Paralelamente, verificou-se a interferência do sinal químico no fluxo de operárias, bem como da carga transportada na velocidade de deslocamento. Utilizando uma trilha com marcação química prévia no início do forrageamento, não se registrou variação da massa vegetal transportada, no entanto, houve redução do fluxo de operárias que saem da colônia e das que retornavam sem transportar carga, bem como da velocidade de deslocamento das operárias com carga. Uma vez que a pista química feromonal interferiu no fluxo de operárias ao longo da trilha de forrageamento, supõe-se que a determinação da carga transportada pode estar relacionada com as interações entre as operárias. No segundo experimento, foi investigado se a atividade individual da forrageira de Acromyrmex subterraneus influencia na determinação do fragmento vegetal transportado. Observando forrageiras individualmente marcadas durante um mesmo evento de forrageamento, foi registrado o número de viagens realizadas transportando fragmento vegetal, no qual verificou-se que a atividade individual da forrageira não interferiu na massa foliar transportada, isto é, a massa do fragmento vegetal transportado foi a mesma independente do número de viagens realizado por uma mesma operária. Registrou-se ainda que maioria das operárias realizou até três viagens, sendo, portanto, a maior parte do transporte de folhas realizado por operárias que não desempenham exclusivamente a atividade de forrageamento, as quais são denominadas de operárias não elite. Sugerindo um esforço coletivo da colônia em garantir o sucesso do forrageamento. Deste modo, inclui-se junto aos fatores físicos, por exemplo, a relação entre tamanho da operária e fragmento e aos mecanismos de coleta e obtenção de recurso, as interações entre os indivíduos da colônia, que se mostram fundamentais para modulação da carga vegetal transportada pelas operárias. / Cutting ant workers collect fresh plant fragments, which are used as substrate for the cultivation of the symbiotic fungus. The diet of cutter ant workers, especially offspring, consists of the consumption of the fungus symbiont, which makes foraging a prime activity for the success of their colonies. Thus, the mass of the plant fragment transported to the colony is directly related to the success of the foraging, since this interferes in the speed of the workers' movement and in the feeding of the colony. To identify the factors that can modulate the determination of the load carried in leaf cutting ants, it was evaluated how the trail pheromone influences the determination of the vegetal fragment carried by the workers of Acromyrmex subterraneus. At the same time, there was interference of the chemical signal in the flow of workers, as well as the load carried in the displacement speed. Using a trail with prior chemical marking at the beginning of foraging, no variation of the transported vegetable mass was recorded, however, there was a reduction in the flow of workers leaving the colony and those returning without carrying cargo, as well as the speed of movement of workers with load. Since the pheromonal chemical track interfered with the flow of workers along the foraging trail, it is assumed that the determination of the transported load may be related to the interactions between the workers. In the second experiment, it was investigated whether the individual activity of the forage of Acromyrmex subterraneus influences the determination of the transported plant fragment. By observing individually tagged forages during the same foraging event, the number of trips carried out carrying vegetable fragment was recorded, in which it was verified that the individual activity of the forage did not interfere in the transported foliar mass, that is, the mass of the transported vegetable fragment was the same independent of the number of trips made by the same worker. It was also recorded that most of the workers had carried out up to three trips, being therefore most of the transport of leaves realized by workers who do not exclusively perform the foraging activity, which are denominated of non-elite workers. Suggesting a colony's collective effort to ensure foraging success. In this way, the physical factors, for example, the relation between worker size and fragment and the mechanisms of collection and obtaining of resources are included, the interactions between the individuals of the colony, which are fundamental for modulation of the transported vegetal load by the workers.

La thèse concerne l’usinage à 5 axes de formes complexes. Le but est d’estimer le plus précisément possible les efforts induits par la coupe pour ajuster la vitesse d’avance et gagner en performance. Pour cela, il est nécessaire d’estimer les engagements radial et axial de la fraise à chaque instant. Ce calcul est rendu particulièrement complexe à cause de la forme de la pièce, de la forme du brut et de la complexité de la géométrie de l’outil. Les méthodes usuelles par Zbuffer sont particulièrement couteuses en temps de calcul. Dans ces travaux nous proposons une méthode de calcul rapide à partir d’une modélisation du contact dans toutes les situations envisageables. Différentes simulations et expérimentations ont permis de valider la précision expérimentalement. / This study presents a simple method to define the Cutter Workpiece Engagement (CWE) during sculptured surface machining in five-axis milling. The instantaneous CWE was defined by determining two engagement points, lowermost engagement (LE)-point and uppermost engagement (UE)-point. LE-point was calculated using a method called grazing method. Meanwhile the UE-point was calculated using a combination of discretization and analytical method. During rough milling and semi-finish milling, the workpiece surface was represented by vertical vector. The method called Toroidal–boundary was employed to obtain the UE-point when it was located on cutting tool at toroidal side. On the other hand, the method called Cylindrical-boundary was used to calculate the UE-point for flat-end cutter and cylindrical side of toroidal cutter. For a free-form workpiece surface, a hybrid method, which is a combination of analytical method and discrete method, was used. All the CWE models proposed in this study were verified and the results proved that the proposed method were accurate. The efficiency of the proposed model in generating CWE was also compared with Z-mapping method. The result confirmed that the proposed model was more efficient in term of computational time. The CWE model was also applied for supporting the method to predict cutting forces. The test results showed that the predicted cutting force has a good agreement with the cutting force generated from the experimental work.

The leaf-cutting antsof the genus Atta and Acromyrmex belong to the order Hymenoptera, Formicidae family, Myrmicinae subfamily and Attini tribe are locatedin the Americas, occurring in tropical areas of Mexico andin Central and South America,are considered herbivorous and difficult to control when attacking crops and forests. The species Atta texana and Acromyrmex versicolor are the only representatives of these ants foundin North America. Several species of the genus Attaare found in Brazil. Understanding the behavior of leaf-cutting ants in their multiple division of laboris a necessary step to establish living with them, and develop or adapt new methods of control, when these reach the economic injury level. There fore, this study sought to clarify the behavior of Atta opaciceps regarding the specificity of behaviors of territory marking and trail, seeing how the different castes respond to different intra and interspecific extracts (Acromyrmex subterraneus subterraneus, A. cephalotes, A. sexdens sexdens and A. sexdens rubropilosa) on laboratory conditions. It also sought to identify the chemical constituents present in the foragers venom gland extracts of A.opaciceps, seeking to know what the compounds responsible fore liciting the trail behavior of foragers of this species. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / As formigas cortadeiras do gênero Attae Acromyrmex pertencem à ordem Himenóptera, família Formicidae, subfamília Myrmicinae e tribo Attini estão localizadas no continente americano, ocorrendo nas áreas tropicais do México e nas Américas Central e do Sul, são consideradas herbívoras e de difícil controle quando atacam as lavouras e florestas. As espécies Atta texana e Acromyrmex versicolor são as únicas representantes destas formigas encontradas na América do Norte. Várias espécies do GêneroAtta são encontradasno Brasil.Entender os comportamentos das formigas cortadeiras em sua múltipla divisão de trabalho constitui uma etapa necessária para estabelecer a convivência com estas, além de desenvolver e, ou adaptar novos métodos de controle, quando essas atingem o nível de dano econômico. Dessa forma, o presente estudo procurou esclarecer o comportamento de Atta opaciceps quanto à especificidade dos comportamentos de marcação de território e de trilha, verificando como as diversas castas respondem a diferentes extratos intra e interespecíficos (Acromyrmex subterraneus subterraneus, A. cephalotes, A. sexdens sexdens e A. sexdens rubropilosa) sob condições de laboratório. Buscou-se também identificar os constituintes químicos presentes nos extratos de glândula de veneno de forrageiras de A. opaciceps, objetivando saber quais os compostos responsáveis pelo eliciamento do comportamento de trilha em forrageiras desta espécie.

The thesis deals with the design, construction, production and testing of cutters with polycrystalline diamond cutting edges. Polycrystalline diamond is a suitable cutting material for machining very abrasive materials such as aluminum alloys or composite materials. The design of the tool is focused on the application of the chip breaker on the front of the tool. The aim of the solution is to reduce the cutting force in the machining of the aluminum alloy used in the aerospace industry. The first part of the thesis deals with problems related to milling technology. The practical part describes the design and construction of prototype cutting tools. Three tools were designed for experimental measurement. The technology of cutting tools made from super hardened cutting materials with laser technology is presented. The experimental part of the thesis is a measurement of the cutting force according to cutting parameters and machined material.

This dissertation work is aimed on grants from the European Union. It denotes about the possible use of grants from the European Structural Funds to support the increase of professional training in the Moravian-Silesian region. Use of these resources should further lead to a unemployment reduction and a literacy increase by citizens who fall in categories to 25 years of age without experience or with an age limit of 50 years.

Mobile Miner 40V is a machine used for rock excavation and developed by Epiroc. This machine is equipped with a large cutter wheel to perform the excavation. After a test run, some surfaces associated with bearings within the cutter wheel were found to be damaged due to scuffing - severe sliding wear. There is a static load applied to the surfaces due to gravity. However, the reason for this damaged issue was believed that there is a large dynamic load applied to the surfaces during the excavation. This dynamic load was not found in a previous FE model used to verify safety issues. Therefore, a new FE model that is more in line with reality, and a failure analysis were required. Additionally, a feasibility study for a cutter wheel with a larger dimension was also needed since a larger cutter wheel is desirable. Firstly, wear mechanisms were reviewed, and some theories were chosen to analyze the damaged issue. Since it was unknown whether the surfaces were well-lubricated or not, both cases were investigated. The Archard wear equation was used to analyze the poor-lubricated situation, while the lubrication number and the Reynolds equation were used to analyze the well-lubricated case. Secondly, contact mechanisms between the surfaces were also investigated. The investigation of the contact mechanisms involved several theories, such as the Hertzian contact theory and the impact load factor. Besides these theoretical analyses, a numerical analysis was performed. Lastly, a new FE model was established in Ansys. Both the cutter wheel which was subjected to scuffing(existing cutter wheel), and the cutter wheel with a larger dimension(larger cutter wheel) were analyzed by the use of the new FE model. The maximum and minimum wear rates obtained by the Archard wear equation are approximately 1.9・10-2mm3/m and 4.8・10-3mm3/m, which are considered as a completely unacceptable level in engineering applications. The maximum and minimum critical loads obtained by the Reynold equation are approximately 1.8kN and 24.8kN, which both are larger than the static load applied to the surfaces. The maximum and minimum critical mean contact pressures obtained by the lubrication number are approximately 65MPa and 240MPa, which both are larger than the mean contact pressure generated by the static load. No evidence shows that there is a large dynamic load applied to the surfaces during the excavation. The largest possible contact pressure on the bearings in the existing cutter wheel is very close to the limit of severely damaged. The largest possible contact pressure on the bearings in the larger cutter wheel is believed to exceed the limit of severely damaged. The previous assumption that the surfaces were damaged due to a large dynamic load was wrong. The obtained results support that the surfaces were only subjected to a static load and were damaged due to inadequate lubrication. The existing cutter wheel is operated safely with the current load cases. However, the forward thrust force is suggested to decrease when the cutting angle is large. There is a high risk if the larger cutter wheel is operated with the current load cases.

No description available.

In der fleischverarbeitenden Industrie gibt es eine Vielzahl von Schneidwerkzeugen. Kuttermesser stehen hierbei in der Prozesskette weit hinten und haben einen direkten Einfluss auf die Qualität des Endprodukts. Der Prozess des Kutterns ist bislang nicht komplett analytisch geklärt. Während des Vorgangs durchläuft das Schneidgut (i.A. das Fleisch bzw. das Brät) wechselnde Aggregatzustände von fester (leicht gefrorener) Form hin zum zähviskosen Zustand. Weiterhin ist es permanentem korrosiven Kontakt ausgesetzt. Die Komplexität macht eine analytische Herangehensweise äußerst aufwendig, sodass sich mittels der FEM durch numerisches Vorgehen und Lastannahmen aus Untersuchungen diesem Problem gewidmet wird. Dabei sind bislang nicht bekannte Potentiale zu erkennen. Hierbei wurden verschiedene Vernetzungsstrategien (p- und h-Methode) der FEM angewandt und verglichen. Es sind dabei Materialreduktionen bis knapp 30% ersichtlich.

Sontech International AB är ett företag som är specialiserade på ljudabsorbenter i metall och skum. De har tagit fram en ljudabsorbent i kartong med slitsar som går längs arket med ett avstånd på max 5 mm mellan dem. Denna produceras idag med en CNC-maskin och det tar 17 minuter per kvadratmeter att producera absorbenten med 5 mm mellan slitsarna. För att produkten ska vara lönsam behöver produktionstiden ned på en minut per kvadratmeter. Det är ett relativt litet företag med stora kunder och har därför inte tid eller resurser att lägga på att utveckla produktionen av den. Därför har författarna fått i ansvar att som examensarbete inom maskinteknik försöka utveckla och till sist presentera en färdig modell på en maskin för lösningen. Efter skisser, prototyper och val mellan tre färdiga modeller på föll valet på maskinen vid namn Krattan. Krattan drivs med två pneumatiska cylindrar som lyfter upp arket och drar vad som kallas krattan som består av 199 knivar tvärs över det. Produktionstiden uppskattas ha sjunkit till ca 20 sekunder per kvadratmeter kartongark. / Sontech International AB is a company that specializes in sound absorbents made of metal and foam. They have a new product that is a sound absorbent made of cardboard with cuts along the sheet of cardboard with a maximum distance between the cuts of 5 mm. This product is made with a CNC-machine and it takes 17 minutes per square meter to produce a sheet with 5 mm between each cut. To make the product viable the production time needs to come down to a minute per square meter. Sontech is are latively small company which is why they have not been able to spare the resources to develop a solution for manufacturing this product. The writers have based their thesis paper in mechanical engineering on developing and presenting a complete model of a machine as a method of production. After many sketches, prototypes and a selection between three different solutions they picked a machine that they refer to as ‘‘The rake’’. ‘’The rake’’ is powered by two pneumatic cylinders. One cylinder lifts the sheet of cardboard and either pushes or pulls ‘’the rake’’ part of the machine that is made of 199 blades. The production time is estimated to be about twenty seconds per square meter of cardboard.

В данной магистерской диссертации представлены разработки и результаты исследования влияния конструктивных решений на теплоотвод при точении резцом с внутренним воздушным охлаждением. Разработана конструкция резца с увеличенным теплоотводом. Она позволяет существенно расширить область использования резцов с внутренним воздушным охлаждением вместо традиционных резцов с охлаждением СОЖ. Результаты диссертационной работы опубликованы в V номере инженерного журнала «Справочник». Также по результатам проведенного исследования был получен патент на полезную модель №209971 «Металлообрабатывающий инструмент с внутренним охлаждением». Магистерская диссертация состоит из введения, 5 глав, заключения. Объем диссертационной работы – 72 страниц, в том числе 33 рисунка, 6 таблиц. Библиографический список содержит 25 источников. / This master's thesis presents the developments and results of a study of the influence of design solutions on heat removal when turning with a cutter with internal air cooling. A cutter design with increased heat sink has been developed. It allows you to significantly expand the scope of use of cutters with internal air cooling instead of traditional cutters with coolant. The results of the dissertation work were published in the 5th issue of the engineering journal Spravochnik. Also, based on the results of the study, a patent for utility model No. 209971 "Metalworking tool with internal cooling" was obtained. Master's thesis consists of introduction, 5 chapters, conclusion. The volume of the dissertation work is 72 pages, including 33 figures, 6 tables. The bibliographic list contains 25 sources.