Academic literature on the topic 'EXTRUSÃO DE TUBOS'
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Journal articles on the topic "EXTRUSÃO DE TUBOS"
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Souza, Shamon H. F., Fernando A. Silva, and Eliane C. Vilela. "Uso de Carbonato de Cálcio na Formulação de Tubos de PVC Rígido." Revista Processos Químicos 3, no. 6 (July 1, 2009): 42–47. http://dx.doi.org/10.19142/rpq.v03i06.p42-47.2009.
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O trabalho consistiu em avaliar o desempenho de dois tipos de carbonato de cálcio (um de origem mineral e outro de origem cretácea) utilizados na formulação de tubos de PVC rígido. Os tubos foram produzidos pelo processo de extrusão e o desempenho do material foi analisado com a realização de testes de controle de qualidade propostos pela ABNT. Os resultados dos testes de qualidade foram bem mais satisfatórios nos tubos que possuíam em sua composição o carbonato de origem cretácea. Para verificar as diferenças existentes entre os carbonatos foi realizada uma análise de difratometria de raios-X, que indicou conformações cristalinas romboédrica e monoclínica para os carbonatos de origem cretácea e mineral, respectivamente. A possível existência de “cantos vivos” na conformação monoclínica do carbonato mineral e consequentemente a formação de espaços vazios na estrutura do polímero teriam causado os resultados negativos nos testes de qualidade do produto final.
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Alves, Juliana P. D., and Antonio Rodolfo Jr. "Análise do processo de gelificação de resinas e compostos de PVC suspensão." Polímeros 16, no. 2 (June 2006): 165–73. http://dx.doi.org/10.1590/s0104-14282006000200018.
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Este artigo busca analisar a relação existente entre o grau de gelificação de compostos de PVC rígido (U-PVC) durante seu processamento e as propriedades mecânicas finais dos produtos obtidos através do processo de extrusão de tubos. Para tanto, a morfologia das resinas de PVC é analisada a fim de se entender seu desenvolvimento ao longo da extrusão e entender sua influência na gelificação já que o desempenho do produto dependerá dessa influência. O desenvolvimento morfológico, devido às condições de processamento e ambiente termo-mecânico, bem como alguns testes como microscopia eletrônica de varredura para monitorar esse desenvolvimento são descritos. O grau de gelificação e sua quantificação são analisados utilizando reometrias de torque, rotacional e capilar, utilizando análises térmicas (DSC) e utilizando imersão em solvente (cloreto de metileno).
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Wruck, Emerson, Lidiane J. Michelini, Pedro H. S. de Paula, Carlos A. S. Júnior, Danilo M. dos Santos, and Ítalo L. Fernandes. "Aplicação da Metodologia “Medidor R&R” em processos de extrusão." Revista Processos Químicos 3, no. 5 (January 2, 2009): 73–82. http://dx.doi.org/10.19142/rpq.v3i5.89.
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O trabalho consistiu em avaliar a capacidade do sistema de medição de um processo de extrusão de tubos de PVC pela metodologia medidor R & R, apoiado pelas cartas do controle estatístico do processo. No experimento realizado, foi constado que grande parte da variabilidade total do processo estava associada à capacidade de medição dos operadores. Foram identificados através da metodologia quais os operadores apresentavam mais dificuldades, além de hábitos de medição inadequados. Dessa forma sugeriu-se um programa de treinamento em medição direcionado, aferição periódica de equipamentos e avaliação constante da capacidade de medição pela metodologia exposta, visando à redução da variabilidade, como conseqüência a diminuição das perdas.
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Rodrigues, A. M., and E. S. Loureiro. "CONFECÇÃO DE UMA COLEÇÃO DE FUNGOS ENTOMOPATOGÊNICOS COM ISOLADOS ENCONTRADOS EM CULTURAS AGRÍCOLAS E AMBIENTES DE PRESERVAÇÃO AMBIENTAL EM MATO GROSSO DO SUL." Arquivos do Instituto Biológico 76, no. 2 (June 2009): 303–6. http://dx.doi.org/10.1590/1808-1657v76p3032009.
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RESUMO Com o avanço do desmatamento, a prática de culturas agrícolas não planejadas e a utilização de defensivos agrícolas tóxicos ao meio ambiente, estima-se que grande parte da diversidade de fungos entomopatogênicos presente no meio ambiente esteja sendo alterada. A preservação na forma de coleção de culturas é uma prática de fundamental importância para a manutenção da biodiversidade destes micro-organismos. Este trabalho objetivou a coleta sistematizada de amostras de solo e de insetos mortos e moribundos que apresentassem a extrusão do patógeno ou com características da doença, em culturas agrícolas e área de preservação ambiental. Os insetos coletados foram identificados e levados para o laboratório, onde se isolou o patógeno em meio de cultura BDA. As placas foram mantidas em B.O.D. a 25± 1° C, 70 ± 10% UR e fotofase de 12 horas, durante 7 dias. Após a obtenção de culturas puras, os conídios foram retirados por meio de raspagem com alça metálica, armazenados em tubos plásticos do tipo Eppendorf, e mantidos em freezer a -4º C. Até o momento foram isolados os fungos entomopatogênicos: Beauveria bassiana, parasitando Lagria villosa (UFGD 01), Hypothenemus hampei (UFGD 06 e UFGD 11), um inseto da família Crisomellidae (UFGD 02) e do solo (UFGD 16); o fungo Metarhizium anisopliae parasitando Zulia entreriana (UFGD 05), Mahanarva fimbriolata (UFGD 03), M. posticata (UFGD 07) e do solo (UFGD 12); Paecilomyces fumosoroseus atacando um inseto da família Scarabaeidae (UFGD 04), Lagria villosa (UFGD 13) e do solo (UFGD 09 e 15); P. farinosus isolado a partir do solo (UFGD 08) e o fungo Nomuraea rileyi parasitando a lagarta Anticarsia gemmatalis (UFGD 14).
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Hu, Hong Jun, Zhao Sun, and Ding Fei Zhang. "Effects of Extrusion-Shear and Direct Extrusion on the Plastic Deformation of AZ31 Magnesium Alloy." Materials Science Forum 913 (February 2018): 176–81. http://dx.doi.org/10.4028/www.scientific.net/msf.913.176.
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Based on characteristics of direct extrusion for magnesium alloy seamless tube and continuous equal channel angular pressing (ECAP) of tubes, a new composite extrusion process of tubes including direct extrusion and many steps ECAP was invented firstly, which are shorten for TES process in this paper. A three-dimensional finite element thermo-mechanical coupled model and conditions for TES process were established. The extrusion process and cumulative strains evolution during TES process were simulated. The results show that TES process can improve the cumulative strains significantly. The microstructures observations of longitudinal sections for tubes fabricated by direct extrusion and TES process were carried out. It was found that when the extrusion temperature was 400°C, and extrusion ratio was 8.4 and the channel angle was 150°, TES process can refine the microstructures of tubes effectively.
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Gibb, Alan G., and Ian J. Mackenzie. "The Extrusion Rate of Grommets." Otolaryngology–Head and Neck Surgery 93, no. 6 (December 1985): 695–99. http://dx.doi.org/10.1177/019459988509300601.
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A prospective study was performed to determine the factors Influencing the extrusion rate of tympanostomy tubes. Nine hundred thirty-nine tubes were inserted In 589 patients and the extrusion of these tubes was reviewed up to a period of 27 months. The eight tubes used in the survey were the Shepard, Exmoor, Bobbin, Armstrong, Paparella, Shah, Arrow, and collar button. These tubes were inserted In strict rotation, the operator using the designated tube. The position, type of incision, presence of fluid, quality of tympanic membrane, and degree of difficulty of insertion were all recorded at operation. The sex, age, side of operation, and any simultaneous operative procedures were also recorded. The patients were reviewed the day after operation and then every 3 months thereafter until the tube was extruded. A definite pattern was Identified for the extrusion of each type of tube. At one end of the spectrum, Exmoor and Shepard tubes were, for the most part, extruded between 6 and 9 months after Insertion, while at the other end, most of the collar button tubes were still functioning at 18 months. The design of the tube was the only factor found to be a significant determinant of the extrusion of the tube, although the experience of the surgeon affected the extrusion rate of the Arrow tube. The different dimensions of the Exmoor and collar button tubes are examined and compared.
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Wang, Ying Xin, Xiao Qin Zeng, Wen Jiang Ding, Alan A. Luo, and Anil K. Sachdev. "Development and Validation of Extrusion Limit Diagram for AZ31 and AM30 Magnesium Alloys." Materials Science Forum 546-549 (May 2007): 327–32. http://dx.doi.org/10.4028/www.scientific.net/msf.546-549.327.
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Uniaxial hot compression tests were performed at constant temperature (T) and strain rate (ε& ) in the ranges of 200-500 °C at an interval of 50 °C and 0.001-20 s-1. The flow stress data were used to develop the extrusion limit diagram for AZ31 and AM30 magnesium tubes. The extrusion limit diagram shows a wide region available for extruding AZ31 and AM30 seamless tubes, and comparison of the two extrusion limit diagrams shows that, the extrudability of AM30 alloy is better than that of AZ31 alloy. Actual extrusion trials validated the predicted temperature rise limit curve corresponding to the occurrence of surface cracking during the extrusion process. Magnesium tubes were successfully extruded according to the safe regions identified by the extrusion limit diagram.
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Furushima, Tsuyoshi, Tetsuhide Shimizu, and Kenichi Manabe. "Grain Refinement by Combined ECAE/Extrusion and Dieless Drawing Processes for AZ31 Magnesium Alloy Tubes." Materials Science Forum 654-656 (June 2010): 735–38. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.735.
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Grain refinement processing by severe deformation, combined equal-channel angular extrusion (ECAE) processing and conventional tube extrusion, is applied to AZ31 magnesium alloy. By a combination of ECAE processing and tube extrusion, a fabricated tube, with outer and inner diameters of 2 mm and 1 mm, respectively, has fine, homogeneous, and equiaxed grain structure with an average grain size of 1.5m. Tensile test results indicate that the fine-grained tubes exhibited a superplasticity potential m value of 0.55.The maximum elongation (688%) is obtained at a temperature of 673K. Furthermore, the tubes fabricated by combined ECAE/extrusion process is applied to dieless drawing process without using any tool and die.As a result, dieless drawing limit is enhanced due to high m value achieved by combined ECAE/Extrusion process. From these results, the effectiveness of new grain refinement processing for fabricating fine-grained tubes and its application for dieless drawing process to fabricate the fine tubes was demonstrated experimentally.
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Hussain, S. S. M. "Extrusion Rate of Shah and Shepard Ventilation Tubes in Children." Ear, Nose & Throat Journal 71, no. 6 (June 1992): 273–75. http://dx.doi.org/10.1177/014556139207100606.
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Shah and Shepard ventilation tubes are the two most commonly used ventilation tube in current practice. In some centres these two tubes are used interchangeably, in others the Shepard is often used as the first ‘grommet’ of insertion and the Shah for subsequent insertions. A study was undertaken of extrusion rate of these ventilation tubes in 180 children who had surgery for Serous otitis media in 1987. Extrusion time was found to be very significantly different between these tubes. The Shah ventilation tube remains in situ 3 months longer than the Shepard. A case is made for the use of Shah ventilation tubes as the first “grommet” of insertion. Otorrhoea following insertion of ventilation tube did not affect the extrusion rate of ventilation tubes in this study. Nor has otorrhoea a predilection for any particular ventilation tube.
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Sahmel, Olga, Stefan Siewert, Klaus-Peter Schmitz, Daniela Arbeiter, Niels Grabow, Christine Friederike Kreiner, and Rudolf Guthoff. "Extrusion as a manufacturing process for polymer micro-tubes for various bio-medical applications." Current Directions in Biomedical Engineering 5, no. 1 (September 1, 2019): 489–91. http://dx.doi.org/10.1515/cdbme-2019-0123.
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AbstractIn various biomedical applications extrusion represents a common manufacturing process for polymeric semi-finished products. Extrusion allows the processing of a wide range of biomaterials, as well as different cross-sectional geometries. The present work focuses on the development of an extrusion process for polymer micro-tubes used for medical devices manufacturing, e.g. microstents for minimally invasive glaucoma therapy. Semi-finished products were manufactured by means of extrusion and dip-coating. Morphology was investigated using biaxial laser measurement and scanning electron microscopy (SEM). For the analysis of mechanical and thermal properties of the specimens uniaxial tensile testing and differential scanning calorimetry (DSC) were performed. While dip-coated micro-tubes reveal a smooth and homogeneous surface, SEM micrographs of extruded micro-tubes exhibit some longitudinal grooves. Mechanical properties of extruded and dip-coated micro-tubes are comparable, so that the presented extrusion process can be regarded suitable for the manufacturing of polymer microtubes in a sub-millimeter scale. A future improvement of nozzle design will allow for a smooth surface of extruded semi-finished products.
Dissertations / Theses on the topic "EXTRUSÃO DE TUBOS"
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Peres, Fabiano Moreno. "Métodos de mecânica da fratura aplicados a polietileno de média densidade destinado à extrusão de tubos." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-15092009-161933/.
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O polietileno de média densidade (PEMD) é um polímero termoplástico parcialmente cristalino, cujo uso tem crescido bastante em aplicações de engenharia, como em tubos plásticos para sistemas de distribuição de água e de gás. Sob carga constante, entretanto, este material pode eventualmente apresentar fratura por fluência, por meio de um mecanismo de crescimento lento de trincas, provocando acentuadas perdas por vazamento nos sistemas. Os métodos atuais empregados pela indústria para estimar a durabilidade dos tubos são caros, demorados, pouco práticos e imprecisos. Busca-se o desenvolvimento de técnicas mais eficientes, sendo que os métodos da mecânica da fratura são promissores no sentido de descrever a etapa de propagação da trinca. Ensaios de mecânica da fratura, entretanto, requerem a introdução de pré-trincas nos corpos de prova. Sabe-se que as técnicas artificiais de introdução de pré-trincas causam algum tipo de dano na matriz polimérica, que pode ou não afetar os resultados dos ensaios, dependendo dos eventos que ocorrerem após o carregamento inicial. A principal propriedade requerida de um método de introdução de pré-trinca, portanto, é reprodutibilidade. Neste estudo foram aplicados três importantes métodos de mecânica da fratura ao PEMD e investigados os efeitos de diferentes técnicas de introdução de pré-trincas sobre os resultados dos ensaios e sobre as estruturas de deformação na matriz do material na ponta da trinca. Os ensaios de tenacidade à fratura no estado plano de deformação - KIc - foram realizados em condições criogênicas, em vista do comportamento dúctil do material à temperatura ambiente, sendo que a estratégia mostrou-se satisfatória. Os resultados dos ensaios de Integral-J sugerem que o método pode não ser aplicável ao PEMD, devido ao peculiar mecanismo de fratura do material. O método do trabalho essencial de fratura - EWF - se aplica bem ao PEMD. Os resultados dos ensaios de KIc e EWF demonstraram que diferentes técnicas de introdução de pré-trincas provocam diferentes estruturas de deformação no material na ponta da trinca e afetam os resultados de ensaios de fratura no PEMD. Os resultados de EWF demonstraram ainda que o processamento também afeta as propriedades de fratura do material. É proposta uma nova técnica para a introdução de pré-trincas, com características mais naturais, a qual requer estudos complementares para seu aperfeiçoamento.Medium density polyethylene (MDPE) is a semicrystalline thermoplastic polymer that has been increasingly used in engineering applications, as plastic pipes for water and gas distribution systems. Under constant load, however, this material may occasionally present creep failure, by means of a mechanism of slow crack growth, leading to leakage losses in the systems. Current methods used by industry to estimate durability of pipes are expensive, time consuming, non practical and inaccurate. The development of more efficient methods is a common target and fracture mechanics methods are promising in describing the crack propagation stage. Fracture mechanics testing methods, however, require the introduction of pre-cracks into the specimens. It is known that artificial methods of introducing pre-cracks produce some damage on the polymeric matrix, which may or not affect the results of tests, depending on the events that occur after the initial loading. Main propriety required of a pre-crack introducing method, therefore, is reproducibility. In this study three important fracture mechanics methods were applied to MDPE and the effects of different methods of pre-cracking over test results and over deformation structures of material matrix at the crack tip were investigated. Plane-strain fracture toughness - KIc tests were performed under cryogenic conditions, in view of the ductile behavior of material at room temperature and this strategy was well succeed. Results of Integral-J tests suggest that this method may not be applicable to MDPE, due to the peculiar fracture mechanism of the material. The essential work of fracture method EWF is well suited to study MDPE. The results of KIc and EWF tests showed that different pre-cracking methods cause different deformation structures in the material at the crack tip and affect the fracture tests with MDPE. EWF results showed also that the processing affect the fracture properties of materials too. It is proposed a new method for introducing pre-cracks, with more natural characteristics that requires complementary studies for its improving.
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Collantes, Hugo David Chirinos. "Desenvolvimento do Processo de Fabricação de Tubos Hospitalares por RVNRL: Otimização e Protótipo de Extrusão a Baixas Temperaturas." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-06112003-182641/.
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O látex de borracha natural foi formulado, radiovulcanizado e, em seguida, estabilizado radioliticamente (GAMATEX), para ser empregado na fabricação de artefatos de borracha utilizados na área médica. A eficiência de reticulação do látex, quando radiovulcanizado com raios gama, correlacionou-se matematicamente com a razão de concentração do sistema de radiosensibilizador (x1 = [An-B] / [KOH]) e com a dose de vulcanização (x2), apresentando alto grau de interação, segundo o seguinte modelo matemático: , onde representa a resistência à tração na ruptura. O processo RVNRL foi otimizado para baixas doses de vulcanização e altas concentrações de An-B. A resistência radioxidativa da borracha, obtida a partir do GAMATEX, foi atingida adicionando-se uma mistura de antioxidantes (45% BANOX S + 55% TNPP). Esta mistura apresentou um efeito sinérgico. O látex apresentou comportamento pseudoplástico com a ocorrência de tensão de escoamento. A taxa de desestabilização irreversível do látex foi diretamente proporcional à [An-B] e inversamente proporcional à [KOH]. O efeito pós-irradiação do látex ou a desestabilização reversível, ocorreu devido à presença de uma concentração residual de An-B que não reagiu. A irradiação melhorou a estabilidade coloidal do GAMATEX, devido ao aumento da tixotropia e da tendência newtoniana além da correlação entre o grau de consistência (k) e o índice pseudoplástico (n), de acordo com o modelo matemático . Este fato permite um tempo maior de estocagem do GAMATEX. A viscosidade relativa do látex correlaciona-se com a temperatura e com o teor da borracha seca conforme o modelo matemático: , onde rw é a razão (BS/100-BS). O látex radiovulcanizado coagulou à temperatura de 10ºC no sistema de refrigeração projetado.The natural rubber latex was formulated, irradiation vulcanized and stabilized (GAMATEX) to make rubber goods for medical purpose. When the latex was vulcanized by gamma rays the effectiveness crosslinking of GAMATEX relationship between the concentration ratio of sensitizer system (x1=[n-BA]/[KOH]) and the vulcanization dose (x2), showing high interaction grade according to the following the mathematical equation: , where is the tensile strength. The RVNRL process was optimized for low vulcanization doses and high concentrations of n-BA. The resistance to radiolitic oxidation of rubber obtained from GAMATEX was attained when one antioxidants mixture (45% BANOX S + 55% TNPP) was added. This mixture exhibited synergetic effect. The latex showed pseudoplastic rheological behavior and the yield stress occurrence. The irreversible destabilization rate of latex was direct proportional to [n-BA] and indirect proportional to [KOH]. The post-irradiation effects or reversible destabilization of latex occurred because there is a residual concentration of [n-BA] that it was not reacted. The colloidal stability of GAMATEX improved with irradiation, showing showing the increase of thixotropic behavior and the tendency to newtonian behavior flow besides the relationship between the viscosity index (k) and the pseudoplastic index (n) according to the mathematical model: . This fact allows the higher storage time of GAMATEX. The relative viscosity of latex was relationship between the temperature and the total dry rubber content according to the mathematical model: , where rw is the ratio (BS/100-BS). The radiation vulcanized latex coagulated at 10ºC into the projected freezing system.
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Peres, Fabiano Moreno. "Desenvolvimento de métodos alternativos para a avaliação da resistência à fratura por fluência de resinas de polietileno utilizadas para a extrusão de tubos de água." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-08112005-092736/.
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O polietileno tem sido muito empregado em transmissão de água potável, particularmente em ramais prediais. Este polímero apresenta vantagens em relação a seus concorrentes, como flexibilidade, baixo preço, facilidade de instalação e resistência à corrosão. Os tubos fabricados com polietileno de alta densidade PEAD, como o material é genericamente conhecido na indústria de saneamento básico no Brasil - são suscetíveis de apresentar falhas em serviço por fratura em fluência, as quais provocam vazamentos e perdas de água e incorrem em maiores custos de manutenção. Os principais fatores que influenciam a vida dos tubos de polietileno são: material, meio, condições de carga e técnicas de instalação. A busca de melhores materiais tem levado a indústria petroquímica ao contínuo desenvolvimento de novas resinas, com maior resistência às falhas, que ocorrem através do crescimento lento de trincas. Essa resistência à falha em serviço dos tubos geralmente é avaliada através de ensaios de resistência à pressão hidrostática interna de longa duração, realizados em diferentes temperaturas. Nestes ensaios observa-se que o PEAD apresenta comportamento dúctil (acompanhado de significativa deformação plástica) e falha em menor período de tempo a níveis elevados de tensão, enquanto que em níveis mais baixos de tensão o material apresenta falhas com aparência frágil - sem deformação plástica visível apreciável - após longos períodos de tempo. As falhas em serviço são predominantemente deste último tipo. Esta transição 'dúctil-frágil' no comportamento do material, pelo menos ao nível da falha macroscópica, é muito importante e precisa ser bem compreendida pois pode abreviar a vida útil do tubo através de falhas precoces. Dados de tensão circunferencial versus tempo de ruptura dos tubos podem ser plotados em escala bi-logarítmica, formando o que se conhece na prática industrial por 'curva de regressão', a qual é linear, com inclinação negativa e com maior inclinação (em módulo) na região correspondente às falhas do modo frágil. Dessa forma, a transição 'dúctil-frágil' apresenta-se na 'curva de regressão' como um ponto de inflexão. A tensão de transição dúctil-frágil é característica de uma dada formulação (composto) e não é facilmente determinada em ensaios conduzidos à temperatura ambiente. Apesar de sua ampla aceitação na indústria os testes de resistência à pressão hidrostática interna de longa duração devem ser criticados pois são muito longos, caros e pouco práticos para efeito de controle de qualidade dos tubos de polietileno. Além disso, a maioria dos dados são coletados a altas pressões internas (ou seja, na região 'dúctil') para economizar tempo, enquanto que os tubos operam na região 'frágil'. A filosofia desses testes, como empregados na indústria, também implica que o tempo de falha é uma propriedade do material, enquanto que fatores extrínsecos, como defeitos introduzidos durante a instalação, podem reduzir o tempo de nucleação da fratura, levando à falha precoce. O crescente emprego de tubos de polietileno em sistemas de distribuição de água, além de outras aplicações, como em sistemas de gás, requer o desenvolvimento de novos métodos de avaliação de desempenho, que levem em conta não apenas o tempo de falha como também os mecanismos de fratura. Busca-se desenvolver métodos de laboratório, de curta duração, para se estabelecer o comportamento dos tubos a longo prazo, principalmente para prevenir falhas precoces, do tipo frágil, dentro do período de vida útil esperado. A mecânica da fratura é justamente a disciplina que estuda o comportamento dos materiais na presença de trincas. Neste sentido duas abordagens são propostas no presente trabalho: 'Ramp Test' e o método do Trabalho Essencial de Fratura. O método do 'ramp test' permite estimar a tensão crítica correspondente à transição dúctil-frágil da 'curva de regressão' a partir de ensaios simples de tração. Por outro lado, o método do Trabalho Essencial de Fratura permite estimar diretamente as partes essencial e não essencial do trabalho específico de fratura. São analisadas cinco resinas provenientes de fornecedores tradicionais de matérias-primas para a produção de tubos de polietileno e duas outras resinas, desenvolvidas para outros fins. Os resultados permitem concluir que os ensaios propostos são viáveis como substitutos ou complementares ao ensaios de resistência à pressão hidrostática na avaliação da tendência de tubos de polietileno apresentarem falhas em serviço.Polyethylene has been largely used in potable water distribution systems, mainly in service lines. This polymer offers many advantages over its competitors: flexibility, low cost, ease installation and corrosion resistance. Pipes made with high density polyethylene HDPE, the generic designation of the material in the sanitation industry in Brazil fail in service by fracture due creep, giving rise to leakage and water losses, resulting in higher maintenance costs. Main factors that affect the service life of polyethylene pipes are: material, environment, load and settlement. The search for improved materials leads the petrochemical industry to the continuous development of new resins, with increased resistance to failure, which occurs via slow crack growth. This resistance to in-service failure is usually measured in long-term hydrostatic strength tests, at different temperatures. In these tests HDPE behaves like ductile material (followed by significant plastic deformation) and fails in lower period of time under high stress levels, whereas under lower stress levels it fails in a brittle-like mode - with no visible permanent plastic deformation - after longer times. Failures in service are mainly brittle-like. This ductile-fragile transition in the behavior of the material at least at macroscopic scale, is very important and must be well understood, because it can abbreviate the service life of the tube, through early failure. Time-stress failure data can be ploted in bi-log scale to form what is known in the industrial praxis as regression curve, which is linear, with negative slopes, and a larger slope in modulus for the brittle-like fracture mode. In this way, the ductile-fragile transition appears as a point of inflection. The 'ductile-to-brittle' transition stress is claracteristic of a given formulation and is not easily determined in tests conducted at room temperatures. In spite of its widespread acceptance in the industry, the long-term hydrostatic strength test must be criticized because it has long duration, is expensive and not practical for pipes quality control. Beside that, most of the data are collected at high inner pressures to save time, while the tube is expected to operate in the 'brittle-like' region. The philosophy of these tests, as used in the industry, also implies that the time-to-failure is a material property, while extrinsic factors may shorten the fracture nucleation time, leading to a premature failure. The rising use of polyethylene pipes in water distribution systems, beside other applications as in gas systems, requires the development of new performance evaluation methods, that take into account not the time to failure but also the fracture mechanisms. It is desirable for developing short-term laboratory tests to establish the long-term behavior of pipes, to prevent premature brittle-like failures in the desired service life. Fracture mechanics is just the subject which studies the behavior of materials in the presence of cracks. In this way, two approaches are suggested for the present work : 'ramp test' and the Essential Work of Fracture method. The 'ramp test' method allows to estimate the critical stress that corresponds to the ductile-brittle transition in the regression curve using standard tensile test samples. On the other hand, the Essential Work of Fracture allows a direct estimation of the essential and the non-essential parts of the specific work of fracture. Five different resins for production of polyethylene pipes obtained from traditional raw material suppliers and two other resins designed for other purposes are analysed. The results allow to conclude that the suggested tests are feasible as substitutes or complementaries to the long-term hydrostatic stress tests to evaluate the tendency of the polyethylene pipes to present service failures.
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CHIRINO, COLLANTES HUGO D. "Desenvolvimento do processo de fabricacao de tubos hospitalares por RVNRL .Otimizacao e prototipo de extrusao a baixas temperaturas." reponame:Repositório Institucional do IPEN, 1999. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10781.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Parant, Olivier. "Etude expérimentale et calcul des contraintes résiduelles dans des tubes extrudés en polyéthylène." Paris, ENMP, 2002. https://pastel.archives-ouvertes.fr/tel-00443735.
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Faria, Cyro Rovath de. "Processing of short fiber reinforced porous CMC and MMC tubes by powder thermoplastic extrusion." Florianópolis, SC, 2011. http://repositorio.ufsc.br/xmlui/handle/123456789/95168.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Florianópolis, 2011Made available in DSpace on 2012-10-25T21:36:28Z (GMT). No. of bitstreams: 1 291138.pdf: 5574443 bytes, checksum: d9a4665c93906c67fe4ca08b67cb339f (MD5)
Materiais com poros interconectados são comumente usados em diversas aplicações de filtragem, como, por exemplo, purificação de água, filtração de metais fundidos e filtração de gases quentes. Se por um lado, os filtros devem conter uma estrutura de elevada porosidade aberta; em contrapartida, esses materiais devem apresentar resistência mecânica suficiente para suportar a queda de pressão durante o processo de filtração. O objetivo deste trabalho foi estudar a viabilidade de produção de tubos porosos, em compósitos de matriz cerâmica e metálica reforçados por fibras, via extrusão termoplástica de pós, para aplicação em processos de filtração. A extrusão termoplástica é um processo contínuo, capaz de promover um alto nível de alinhamento de fibras na direção de extrusão, sem que haja excessiva fratura de fibras durante o processamento. Pós de alumina e superliga de níquel foram selecionados para formar a matriz dos compósitos de matriz cerâmica e metálica, respectivamente. Fibras curtas de alumina foram utilizadas como reforço. Como componentes do sistema ligante foram utilizados polietileno de baixa densidade (LDPE), parafina (PW) e ácido esteárico (SA). Diferentes proporções entre LDPE-PW-SA foram estudadas a fim de desenvolver um sistema ligante apropriado ao processo. A evolução da viscosidade da mistura em função do teor de sólidos foi estudada e comparada a diversos modelos de viscosidade. Após o desenvolvimento do feedstock de extrusão, 30 % em volume de fibras foram adicionadas a mistura. Tubos com 4,5 a 10,0 mm de diâmetro, com 0,6 e 1,0 mm de espessura foram então extrudados com sucesso, após sucessivas etapas de ajuste dos parâmetros de extrusão. Análises microscópicas confirmaram o alinhamento satisfatório das fibras. Finalmente, após a sinterização dos tubos a 1300 ºC durante 60 minutos, meso e macroporosidades foram identificadas através de análises porosimétricas por intrusão de mercúrio, totalizando um volume de poros de, aproximadamente, 41 e 36 % nos tubos de matriz cerâmica e metálica, respectivamente. O nível de porosidade, bem como o tamanho médio de poros, foi considerado adequado à aplicação em certos processos de filtração, em especial a filtração de gases quentes.
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Truchassou, Anne-Sophie. "Etude de la résistance aux chocs de tubes PVC à parois structurées : influence du procédé de fabrication sur les propriétés finales." Université Louis Pasteur (Strasbourg) (1971-2008), 2007. https://publication-theses.unistra.fr/public/theses_doctorat/2007/LICHTLE_Anne-Sophie_2007.pdf.
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Actuellement, les tubes PVC multi-couches dédiés aux systèmes d'assainissement ne garantissent pas une résistance aux chocs suffisante. Une étude a donc été menée pour améliorer la ténacité des tubes. L'analyse du procédé de fabrication, l'extrusion, montre que ce processus est complexe. Les propriétés attendues des tubes dépendent de paramètres liés au procédé de fabrication ainsi qu'à ceux liés produit. Il existe une réelle difficulté à déterminer les paramètres cruciaux sur lesquels agir pour améliorer la ténacité. Afin de les identifier, des tests de chocs instrumentés ont été réalisés. Ces tests montrent que la ténacité n'est pas homogène autour du tube. Il existe des zones de plus faible résistance au niveau des surfaces de recollement créées lors de la fabrication. Pour limiter l'impact de ces surfaces sur la ténacité des tubes, un modèle numérique en 3D de l'écoulement de la matière dans la tête d'extrusion a été mis en place. Une modification de l'outillage a été proposéeCurrently, the multi-layer PVC pipes, used for sewage systems does not guarantee an enough impact resistance. A study was thus undertaken to improve the toughness of pipes. The analyse of the manufacturing process, the extrusion, shows that this process is complex. The awaited properties of the pipes depend on parameters related to the manufacturing process like to the product. It exists a real difficulty to find the crucial parameters on which to act to improve the toughness. To identify them, instrumented impact tests were realized. These tests show that thoughness is not homogeneous aroud the pipe. There are zones of weakest strength to the level of the welding surfaces, created during the manufacturing. To reduce the impact of these surfaces on the pipe toughness, a 3D numerical model of the melt flow was set up. A modification of the dies was proposed
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Parant, Olivier. "Étude expérimentale et calcul des contraintes résiduelles dans des tubes extrudés en polyéthylène." Phd thesis, École Nationale Supérieure des Mines de Paris, 2002. http://tel.archives-ouvertes.fr/tel-00443735.
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Notre objectif dans cette étude aura été de se rapprocher progressivement du comportement et des caractéristiques des polyéthylènes afin de décrire les mécanismes de formation des contraintes résiduelles lors du calibrage des tubes.Le modèle le plus simple, basé sur une loi de comportement liquide - solide élastique, a mis en évidence deux mécanismes de formation des contraintes résiduelles. Le premier est relié aux différences de température lors du refroidissement qui provoquent des différences de retrait dans l'épaisseur. Ceci met les couches extérieures du tube en compression et les couches intérieures en traction. Ce profil de contrainte fait se refermer le tube lorsqu'on le découpe suivant la génératrice
Le second mécanisme est relié aux efforts extérieurs qui s'appliquent sur le tube. La dépression dans le calibreur maintient le tube contre la chambre de calibrage et l'empêche de se rétracter lors du refroidissement ce qui induit des contraintes de traction dans les couches solidifiées. En fait la dépression bloque le retrait thermique qui était à l'origine du premier mécanisme. Si la dépression est suffisante pour maintenir le tube jusqu'à la fin de la solidification le profil de contraintes résiduelles est nul. Les profils de contraintes intermédiaires sont obtenus par une évolution des conditions aux limites lors de la solidification, la dépression n'étant en faite pas suffisante pour maintenir le contact pendant toute la solidification.
Le modèle élastique a également mis en avant l'influence des forces axiales et en particulier les forces de frottement entre le tube et la chambre de calibrage. En étirant le tube, elles tendent à diminuer son diamètre. La dépression bloque cette rétraction en plus du retrait thermique. Ceci accentue les contraintes de traction dans les couches extérieures jusqu'à inverser le profil des contraintes résiduelles. Le tube peut alors s'ouvrir lorsqu'on le découpe suivant la génératrice.
Le modèle élastique est suffisant pour expliquer l'influence de la dépression sur le profil des contraintes résiduelles. Cependant les propriétés des matériaux que ce modèle peut prendre en compte restent assez éloignées de celui des polyéthylènes pendant le refroidissement.
Le modèle viscoélastique que nous avons développé est original par rapport à la bibliographie dans le sens où la variation du volume spécifique et les propriétés mécanique lors de la transition fluide -- solide sont directement basés sur l'évolution du taux de cristallinité, paramètre du premier ordre sur le comportement physique du matériau.
Le taux de cristallinité peut être obtenu dans le modèle soit par le modèle de cristallisation d'Ozawa soit en reprenant directement les résultats obtenus par DSC. Celui-ci est alors utilisé pour déterminer l'évolution du volume spécifique et permet de tenir de l'importante rétraction du matériau qui se produit lors de la cristallisation. L'influence du retrait du à la cristallisation doit cependant être nuancé car il se produit à des températures pour lesquelles la relaxation des contraintes n'est pas négligeable. Pour des matériaux semi-cristallins tel que les polyéthylènes, il est donc nécessaire d'utiliser un modèle viscoélastique pour pouvoir prendre en compte le retrait lors de la cristallisation.
Afin de pouvoir appliquer les forces d'étirage et de frottement dès le début de la solidification, nous avons montré qu'il était nécessaire de tenir compte des contraintes dans les couches non solidifiées afin de charger progressivement les couches solidifiées. Le comportement viscoélastique des matériaux est pris en compte dans les états fluides et solide par des lois de Maxwell multimode. La répartition des contraintes prédit dans les couches fluides et solides par le modèle viscoélastique permet d'avoir une première information sur l'importance des propriétés mécaniques du matériau à l'état fluide. Les calculs permettent d'expliquer en partie l'orientation mesurée dans les couches extérieures lors de l'étude des polyéthylènes basse densité linéaire.
Le modèle viscoélastique apporte peu de renseignements supplémentaires sur les mécanismes de formation des contraintes résiduelles finales mais il permet de les quantifier en utilisant des caractéristiques matériaux proches de celles des polyéthylènes lors du refroidissement.
Une étude numérique confirme que le procédé de calibrage est relativement sensible à tous les paramètres du procédé et caractéristiques du matériau même si la dépression reste le paramètre de premier ordre.
Finalement, les comparaisons entre les calculs et l'expérience montrent que nous sommes parvenus à borner la réalité en expliquant l'origine des contraintes résiduelles qui se forment lors du calibrage des tubes.
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Carin, Aurélien. "Etude expérimentale et modélisation thermomécanique de l'étape de calibration dans le procédé d'extrusion de tubes en polyamide 12." Paris, ENMP, 2005. http://www.theses.fr/2005ENMP1313.
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Dans le procédé d’extrusion de tubes en polyamide 12, l’étape de calibration a une influence prépondérante sur les propriétés mécaniques résultantes. La calibration combine une trempe et un étirage des couches extérieures du tube, ce qui conduit à une orientation moléculaire importante dans cette zone. Nous avons montré qu’augmenter la lubrification dans le calibre amène à une diminution du taux d’étirage dans le calibre, DrCAL (rapport entre la vitesse de ligne et la vitesse en entrée de calibre). Une corrélation nette a été montrée entre la biréfringence en peau (DnPEAU) et DrCAL: réduire DrCAL conduit à une orientation plus faible en surface. Une modélisation thermomécanique a permis de déterminer la carte de température au cours du refroidissement, et de montrer de quelle manière les forces d’étirage se concentrent en peau. DnPEAU a été relié aux propriétés mécaniques : l’allongement à la rupture augmente lorsque l’orientation diminueIn polyamide 12 tube extrusion, calibration - or sizing - is the key step that affects subsequent mechanical properties. Influence of calibration is twofold. Since it combines a quenching and a mechanical drawing of the tube external surface, high molecular orientation is generated in this zone. We have shown quantitatively that increasing the lubrication level leads to a diminution of the draw ratio in calibrator, DrCAL (ratio between line velocity and velocity at the calibrator entrance). Excellent correlation has been found between tube superficial orientation (Dn) and DrCAL: a reduced elongation of the polymer in the calibrator leads to less superficial orientation. A thermomechanical model was used to predict temperatures in the tube thickness and to show how drawing forces, concentrated at the external skin during the crystallization, lead to orientation. Besides, elongation at break has been found to strongly depend on Dn and on the surface defects resulting from calibration
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Ozcan, Aysenur. "Investigating The Extrusion Of Alumina Silicate Pastes For Synthesis Of Monolith Zeolite A." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606469/index.pdf.
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Zeolites are highly porous materials that are most commonly used in granular or beaded forms. In general, zeolite granules, beads or monoliths are manufactured by using an inorganic binder which helps to cement zeolite crystals together. However, this inorganic binder decreases the purity of the zeolite structures and accessibility to the zeolite pores. A new and relatively easy method was offered for the production of binderless zeolite A tubes and bars from amorphous alumina silicate extrudates in this study. Amorphous alumina silicate powder, which is obtained by filtering the homogenous hydrogel with a composition of 2.5Na2O:1Al2O3:1.7SiO2:150H2O, is mixed with an organic binder (HEC-Hydroxyethyl Cellulose) to obtain the paste. The paste is then extruded through a die of a home-made extruder into bars and tubes. These extrudates were dried at room temperature for 24 hours, then calcined at 600oC for 2
hours and finally synthesized at 80oC for 72 hours in hydrothermal conditions to convert amorphous alumina silicate to zeolite.
The most appropriate amorphous alumina silicate powder (A) / 4wt% HEC solution (H) ratio to prepare paste, hence to prepare bars and tubes was found as 0.82. The crystallinity of bars and tubes was 91% and 97%, respectively, and zeolite A was the only crystalline material. The bars and tubes were composed of highly intergrown zeolite A crystals with high porosity. Porosity of the bars is approximately 39% and porosity of the tubes is 29%, with a narrow pore size distribution. Bars have macropores of 2 μ
m, while the macropores of the tubes are 3-4 &
#956
m. The BET surface area of the bars was 411 m2/g and of tubes was 439 m2/g, which are comparable with the commercial zeolite A beads. Bars had a crushing strength of 0.42 MPa, which is sufficiently high to handle. In conclusion, zeolite A bars and tubes, with their high purity, macroporous structure and high mechanical strength, can be used in adsorption and ion exchange processes. The developed synthesis method can be scaled up to prepare honeycomb monoliths that provide higher surface are per unit volume with an appropriate extruder die.
Books on the topic "EXTRUSÃO DE TUBOS"
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Liang, Zheng. Co-extrusion of multilayer tubes. Birmingham: University of Birmingham, 1999.
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American Society for Metals Extrusion and Drawing Committee., ed. 9th ASM Conference on Advances in the Production of Tubes, Bars, and, Shapes. [Metals Park, Ohio]: American Society for Metals, 1985.
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ASM Conference on Advances in the Production of Tubes, Bars, and Shapes (10th 1986 Orlando, Fla.). 10th ASM Conference on Advances in the Production of Tubes, Bars, and Shapes: Orlando, Florida, 9-10 October 1986. [Metals Park, Ohio]: ASM International, 1987.
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Die Design for Extrusion of Pipes and Tubes: A Practical Guide. Hanser Publications, 2017.
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10th ASM Conference on Advances in the Production of Tubes, Bars, and Shapes: Orlando, Florida, 9-10 October 1986. ASM International, 1987.
Find full textBook chapters on the topic "EXTRUSÃO DE TUBOS"
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Kainth, Sushil. "Materials for Extrusion Dies." In Die Design for Extrusion of Plastic Tubes and Pipes, 331–40. München: Carl Hanser Verlag GmbH & Co. KG, 2017. http://dx.doi.org/10.3139/9781569906736.014.
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Kainth, Sushil. "Die Design: Basic Considerations." In Die Design for Extrusion of Plastic Tubes and Pipes, 1–10. München: Carl Hanser Verlag GmbH & Co. KG, 2017. http://dx.doi.org/10.3139/9781569906736.001.
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Kainth, Sushil. "Project Planning." In Die Design for Extrusion of Plastic Tubes and Pipes, 11–21. München: Carl Hanser Verlag GmbH & Co. KG, 2017. http://dx.doi.org/10.3139/9781569906736.002.
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Kainth, Sushil. "Design of a Simple Die." In Die Design for Extrusion of Plastic Tubes and Pipes, 23–49. München: Carl Hanser Verlag GmbH & Co. KG, 2017. http://dx.doi.org/10.3139/9781569906736.003.
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Kainth, Sushil. "Simulation of Melt Flow." In Die Design for Extrusion of Plastic Tubes and Pipes, 51–64. München: Carl Hanser Verlag GmbH & Co. KG, 2017. http://dx.doi.org/10.3139/9781569906736.004.
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Kainth, Sushil. "Spiral Die." In Die Design for Extrusion of Plastic Tubes and Pipes, 65–106. München: Carl Hanser Verlag GmbH & Co. KG, 2017. http://dx.doi.org/10.3139/9781569906736.005.
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Kainth, Sushil. "Monolayer Die for Tubes ø1 mm to ø6 mm." In Die Design for Extrusion of Plastic Tubes and Pipes, 107–25. München: Carl Hanser Verlag GmbH & Co. KG, 2017. http://dx.doi.org/10.3139/9781569906736.006.
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Kainth, Sushil. "Monolayer Die for Tubes ø4 mm to ø16 mm." In Die Design for Extrusion of Plastic Tubes and Pipes, 127–60. München: Carl Hanser Verlag GmbH & Co. KG, 2017. http://dx.doi.org/10.3139/9781569906736.007.
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Kainth, Sushil. "Monolayer Die for Pipes ø50 mm to ø125 mm." In Die Design for Extrusion of Plastic Tubes and Pipes, 161–89. München: Carl Hanser Verlag GmbH & Co. KG, 2017. http://dx.doi.org/10.3139/9781569906736.008.
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Kainth, Sushil. "Monolayer Die for Pipes ø140 mm to ø315 mm." In Die Design for Extrusion of Plastic Tubes and Pipes, 191–221. München: Carl Hanser Verlag GmbH & Co. KG, 2017. http://dx.doi.org/10.3139/9781569906736.009.
Full textConference papers on the topic "EXTRUSÃO DE TUBOS"
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THIRUVARUDCHELVAN, SINNATHAMBY, and TAY MENG LEONG. "SEMI-CONTINUOUS EXTRUSION OF ALUMINIUM TUBES." In Proceedings of the Third Australasian Congress on Applied Mechanics. WORLD SCIENTIFIC, 2002. http://dx.doi.org/10.1142/9789812777973_0059.
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Hwang, Yeong-Maw, Song-Jeng Huang, and Yu-San Huang. "Manufacturing of SiCp Reinforced Magnesium Composite Tubes by Hot Extrusion Processes." In THE 14TH INTERNATIONAL ESAFORM CONFERENCE ON MATERIAL FORMING: ESAFORM 2011. AIP, 2011. http://dx.doi.org/10.1063/1.3589752.
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Abu-Farha, Fadi. "Spiral Friction Stir Processing (SFSP) for the Extrusion of Lightweight Alloy Tubes." In ASME 2012 International Manufacturing Science and Engineering Conference collocated with the 40th North American Manufacturing Research Conference and in participation with the International Conference on Tribology Materials and Processing. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/msec2012-7358.
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While friction stir processing (FSP) has been used to refine the grain structure in sheet metals, this work explores the potentials of refining the grain structure of bulk material using the friction stirring phenomenon via the novel concept of spiral friction stir processing (SFSP). With this concept, the rotating stirring tool is plunged into the material, rather than being traversed across it as in FSP; this imposes severe plastic deformation on the material while pushing it radially outwards in complex spiral paths. By confining the material within a closed cylindrical die, the processed material is microstructurally-refined while forming a tube via a special form of SFSP called “friction stir back extrusion” (FSBE). The hypothesised concept was investigated using samples from the AA6063-T52 aluminium alloy and the AZ31B-F magnesium alloy. The preliminary results presented here demonstrate the viability of SFSP, and the special form of FSBE, in producing tubular samples that are structurally sound, with no signs of voids or internal channels. Optical microscopy was performed at key locations within selected tube specimens, and the obtained micrographs clearly show the presence of a stir zone with a fine grain structure; grain size measurements demonstrate the effectiveness of the processing technique in refining the microstructure of the starting material.
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Loretz, Thomas J., Albert R. Hilton, Sr., A. R. Hilton, Jr., and James McCord. "Fabrication of chalcogenide glass rods and tubes by processor-controlled extrusion techniques." In BiOS '97, Part of Photonics West, edited by Abraham Katzir and James A. Harrington. SPIE, 1997. http://dx.doi.org/10.1117/12.271021.
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Emblom, William J., Robin Babineaux, Charles Nix, Katie Parr, Tyler Saltzman, Ayotunde Olayinka, Scott W. Wagner, and Muhammad A. Wahab. "Friction Stir Back Extrusion: Tooling and Process Design for AL-1100-O." In ASME 2018 13th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/msec2018-6515.
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Friction stir back extrusion has recently been identified as a method for manufacturing stronger, more ductile seamless tubes. The long term goal of the project described here is to miniaturize the process in order to produce highly ductile microscale tubes for biomedical, microscale heat exchanger, and fuel cell manufacturing applications. The process is similar to friction stir welding and processing in that the end of a non-cutting tool rotates against a metal workpiece, heats the workpiece, and creates an ultrafine grain structure. Conventional microtube manufacturing is done by hot direct extrusion using dies with mandrels. After the workpiece passes the mandrels, the tube segments weld together from residual heat. The work described here considers macroscale tooling design prior to down scaling to the multi and microscale. The immediate objective was to develop tooling that can produce 50mm long tubes with 12.5mm outside diameters and 6.35mm inside diameters. Design considerations such as strength, fatigue, buckling, and vibration were considered. This paper documents the development of the tooling design process that was used in order to overcome the various design issues. Tooling failure and analysis is presented as part of the evolution of the tooling design. While majority of the paper discusses the tooling design process, a final design was developed and preliminary results for friction stir back extrusion tests are presented for tubes that are 25 and 50mm long.
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Menard, Austin, Clarissa Gallardo, William J. Emblom, Scott W. Wagner, Ayotunde Olayinka, Clayton Loehn, Daniel Seguin, and Muhammad A. Wahab. "Friction Stir Back Extrusion: Preliminary Investigations on Through-Wall Characteristics for Al-1100-O." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-86318.
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Friction stir back extrusion has recently been identified as a method for manufacturing stronger, more ductile seamless tubes. However, most of the work to date has investigated tubes with low length to diameter ratios and there has been little work investigating the change in grain through the thickness of the tube wall. The current project presents preliminary results in an investigation of the effect of the stirring process on developing ultrafine grain through the tube wall. The long term goal of the project is to miniaturize the process in order to produce highly ductile microscale tubes for biomedical applicaions, microscale heat exchangers, and fuel cell manufacturing applications. Friction stir back extrusion is a variation of friction stir processing and friction stir welding in that the end of a non-cutting tool rotates against a metal work piece, heats the work piece, and creates an ultrafine grain structure. The work described here considers tool speed and diameters when forming tubes from A1100-O aluminum work pieces. It was found that for rotations varying from 750 RPM to 2000 RPM that the maximum stir zone was approximately 250 μm at the bottom of the tube and approximately 50 μm in the walls. The outside diameter of the tubes was 12.5 mm and inside diameters of 6.35 mm and 9.3mm were produced.
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Gaillac, Alexis, and Céline Ly. "Optimized manufacture of nuclear fuel cladding tubes by FEA of hot extrusion and cold pilgering processes." In PROCEEDINGS OF THE 21ST INTERNATIONAL ESAFORM CONFERENCE ON MATERIAL FORMING: ESAFORM 2018. Author(s), 2018. http://dx.doi.org/10.1063/1.5034848.
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Milner, Justin L., and Fadi Abu-Farha. "On the Manufacture of Lightweight Alloy Tubes via Friction Stir Back Extrusion: Process Evaluation and Material Performance." In ASME 2014 International Manufacturing Science and Engineering Conference collocated with the JSME 2014 International Conference on Materials and Processing and the 42nd North American Manufacturing Research Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/msec2014-4148.
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A new manufacturing approach in which the friction stirring phenomenon is used as a vehicle for facilitating the deformation of bulk lightweight materials into manufactured components has been recently introduced under the general concept of “bulk friction stir forming”. In a preliminary work, the concept was applied to the back extrusion process, in what was referred to as “friction stir back extrusion” or FSBE; it was shown that the concept is practically valid and FSBE is capable of producing lightweight tubular specimens. Nevertheless, the FSBE process was claimed to have several merits over conventional processes, mainly: (i) unique process capabilities and energy efficiency (ii) significant grain refinement, and thus (iii) favorable mechanical properties in the formed tubes. None of these claims were adequately addressed nor quantified in earlier work. Therefore, this work presents a comprehensive study that aims to reveal the true merits of FSBE, validate the claims, and quantify its effects on the microstructure and mechanical properties of the deformed material. The outcomes of the study are presented in three major parts, each addressing one of the abovementioned claims. Force, torque and power measurements during FSBE experiments are used to address the first claim. Detailed optical microscopy and electron back scatter diffraction work is carried out in the second part to quantify the changes to the grain structure and texture of the material. Finally, the third part presents detailed mechanical characterization using digital image correlation to quantify the effects of FSBE on the performance of the produced tubes.
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Yu, Ilhan, Roland Chen, and Samantha Grindrod. "Fabrication of Gellan Gum Tubular Structure Using Coaxial Needles: A Study on Wall Thickness and Encapsulation." In ASME 2018 13th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/msec2018-6614.
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Tubular structures of hydrogel are used in a variety of applications such as 3D cell culturing for delivery of nutrient supplies. The wall thickness of the tube determines the speed of diffusion or delivery rate. In this study, we aimed to fabricate tubular structures with varying of wall thicknesses using a thermal-crosslinking hydrogel, gellan gum, with the coaxial needle approach. The wall thickness is controlled by changing the flow rate ratio between the inner (phosphate-buffered saline) and outer needles (gellan gum). A simulation model was developed to estimate the proper extrusion speed to allow the gellan gum to be extruded around its glass transition temperature. While keeping the extrusion rate of gellan gum fixed, different PBS extrusion rates were tested to investigate the printability to form continuous tubular structures, range of printable wall thickness, and possibility to form tubes with closed ends to encapsulate fluid or drug inside the tube. The ranges of printable wall thickness with two pairs of coaxial needle were identified. It was found that at about 200% of the baseline PBS extrusion speed, a maximum of 20% difference in wall thickness can be achieved, while a close end can still be formed.
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Emblom, William J., Scott Wagner, Ayotunde Olayinka, Courtnei Richard, Quinn Anglada, Paige Cutright, Andrew Granger, Jonathan Matthysen, and Muhammad A. Wahab. "Preliminary Results: The Design, Instrumentation, and Performance of FSBE Tooling for Aluminum Tubes." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-10032.
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Abstract Friction stir back extrusion (FSBE) has been identified as a manufacturing method for producing tubing with both stronger and more ductile tubing for applications such as hydroforming, biomedical, energy, and MEMS. Additionally, FSBE has been identified as a technology that can be potentially down scaled. However, the process is still not fully understood because of the multitude of process parameters such as geometry, work piece material, friction and heat transfer, and other parameters that go into producing tubes. The goal of this project was to design and test instrumented tooling for FSBE that were capable of producing a wide variety of tubing diameters, measure temperature and force in real-time both, and save process data for further analysis. The current status of this project is that the die has been fully instrumented and tested for measuring temperature, a design for the tool holder and probe capable of measuring plunge force for a CNC mill has been completed, and sample tests measuring temperature have been performed. In addition, a simple steady state heat transfer analysis has shown that the work pieces were approximately 29 degrees hotter than the temperature at the thermal couple. Those temperatures are above the recrystallization temperature of 150°C. Tooling geometry, and a comparison of test results are presented and the future uses for this tooling are discussed.
Reports on the topic "EXTRUSÃO DE TUBOS"
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Misiolek, W. Z., and V. K. Sikka. Physical and Numerical Analysis of Extrusion Process for Production of Bimetallic Tubes. Office of Scientific and Technical Information (OSTI), August 2006. http://dx.doi.org/10.2172/889030.
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