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Yang, Haoliang. "Creep age forming investigation on aluminum alloy 2219 and related studies." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/39352.
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By the middle of the 20th Century, traditional mechanical metal forming methods were showing to be inadequate for producing components comprising of large high strength aluminium alloy panels with complex curvatures, such as those used in modern aircraft and aerospace metal structures. To deal with this problem, a new forming method was conceived by Textron, which has proven to be very useful for forming components with these shape characteristics and good mechanical properties. The method is called Creep Age Forming (CAF). The research described in this thesis is a study of CAF of a 2219 aluminium alloy, which is used for fabricating the isogrid structure for fuel tanks of launch vehicles. The main aim of the research is to develop experimental and modelling tools for CAF of AA2219 sheet structures. A series of creep-ageing tests and stress-relaxation tests have been conducted on AA2219 at 175 °C. The age-hardening, creep deformation and stress relaxation behaviour of AA2219 have been investigated. Based on the experimental investigation, a novel set of physically based, unified creep constitutive equations has been established. A small scale CAF test rig was designed to validate the springback prediction from FE simulation. The experimental result and simulation are in good agreement. Development of FE procedures for simulating creep-ageing behaviour of the material and springback has been performed to predict and assess the springback behaviour of metal sheet in typical forming tools.
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Nguyen, Vu Thua 1965. "Prediction of spring-back in thin sheet of aluminium alloy." Monash University, School of Physics and Materials Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/5855.
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Imbert, Boyd Jose. "Increased Formability and the Effects of the Tool/Sheet Interaction in Electromagnetic Forming of Aluminum Alloy Sheet." Thesis, University of Waterloo, 2005. http://hdl.handle.net/10012/857.
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This thesis presents the results of experimental and numerical work carried out to determine if electromagnetic forming (EMF) increases the formability of aluminum alloy sheet and, if so, to determine the mechanisms that play a role in the increased formability. To this end, free form (open cavity) and conical in-die samples were produced to isolate high strain rate constitutive and inertial effects from the effects of the interaction between the die and the sheet. Aluminum alloys AA5754 and AA6111 in the form of 1mm sheet were chosen since they are currently used in automotive production and are candidates for lightweight body panels. The experiments showed significant increases in formability in the conical die samples in areas where significant contact with the tool occurred, with no significant increase recorded for the free-formed samples. This indicates that the tool/sheet interaction is playing the dominant role in the increase in formability observed. Metallographic and fractographic analysis performed on the samples showed evidence of microvoid damage suppression, which may be a contributing factor to the increase in formability. Numerical modeling was undertaken to analyse the details of the forming operation and to determine the mechanisms behind the increased formability. The numerical calculations were performed with an explicit dynamic finite element structural code, using an analytical electromagnetic pressure distribution. Microvoid damage evolution was predicted using a microvoid damage subroutine based on the Gurson-Tvergaard-Needleman constitutive model. From the models it has been determined that the free forming process is essentially a plane-stress process. In contrast, the tool/sheet interaction produced in cone forming makes the process unique. When the sheet makes contact with the tool, it is subject to forces generated due to the impact, and very rapid bending and straightening. These combine to produce complex non-linear stress and strain histories, which render the process non-plane stress and thus make it significantly different from conventional sheet forming processes. Another characteristic of the process is that the majority of the plastic deformation occurs at impact, leading to strain rates on the order of 10,000 s-1. It is concluded that the rapid impact, bending and straightening that results from the tool/sheet interaction is the main cause of the increased formability observed in EM forming.
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Sutton, Scott Christopher. "Characterization and Modeling of Lightweight Alloys in the Warm Forming Regime." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524129785253984.
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Shah, Manan Kanti. "Material Characterization and Forming of Light Weight Alloys at Elevated Temperature." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306939665.
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Alves, José Augusto Camargo. "Estudo da conformabilidade de abas convexas da liga de alumínio AA2024-O no processo de hidroconformação de chapas." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264433.
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Orientador: Sérgio Tonini ButtonDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: O processo sheet hydroform, ou hidroconformação de chapas, é realizado por meio de uma prensa composta por uma membrana de borracha, preenchido com um fluido hidráulico cuja função é atuar como uma matriz, exercendo esforços sobre uma chapa de metal (blank), que é então empurrada contra um punção rígido, fazendo-o adquirir o formato deste. Embora este processo seja amplamente utilizado para a produção de pequenos lotes de peças metálicas de formato complexo e de espessura reduzida, ele exige habilidades de quem o define, pois se por um lado pode ser visto como simples por empregar apenas um molde maciço, por outro, a ausência de um sistema macho-fêmea capaz de garantir um completo travamento do blank pode ser encarado como um problema por permitir movimentos indesejados do material, que muitas vezes resultam na formação de rugas ou outros defeitos. Baseando-se nesses conceitos, o propósito deste trabalho foi o de mapear, por meio de simulações e ensaios práticos, a conformabilidade de abas convexas da liga de alumínio AA2024-0 de quatro espessuras quando submetidas a diferentes combinações de raio de curvatura e comprimento de aba. Deste modo, foi possível definir quais combinações destes parâmetros possibilitam a obtenção de componentes conformados adequadamente, isentos de rugas e outros defeitos macroscópicos, e ainda, quais condições levam à formação de irregularidades na aba conformada acima do limite preestabelecido, exigindo o emprego de prensa-chapas especiais, também conhecidos como dams, capazes de evitar a ocorrência de tais desvios. Com base nos resultados obtidos pode-se constatar que a ocorrência de rugas está associada principalmente à altura da aba conformada e não se altera significativamente quando a espessura do blank é modificada. Além disso, foi possível notar que raios de curvaturas maiores proporcionam menores valores de deformação compressiva na região conformada, permitindo obter abas mais altas e sem rugas
Abstract: Hydroform, or sheet metal fluid forming, is performed using a fluid cell press, in which the hydraulic fluid acts on the metallic blank pushing it against the male tool, acquiring its geometry. It is widely employed to manufacture small batches of complex and low thick components. If by one point of view it can be seen as simple, involving just a single rigid block as tool, by the other hand the absence of a rigid punch in certain cases can be a limitation, since it may allow the blank to move incorrectly during the process, causing wrinkles or other macro defects. Based on this limitation, the aim of this study was to define, using computational simulations and practical tests, the shrink flange formability limit of four different thickness aluminum alloy sheets when submitted to different combinations of curvature radius and flange length. As result, it could be seen which combinations can lead the material to be formed properly and which may cause failures, requiring special blank holders, known as dams, to avoid this problems. Based on the results, it can be verified that wrinkles nucleation is mainly associated with flange height and it does not change significantly when using blanks with different thicknesses. Furthermore, it could be noted that bigger curvature radius implies in smaller compressive strain on formed region, allowing to obtain higher flanges without wrinkles in these conditions
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
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Otomar, Heber Pires. "Estudo comparativo da estampabilidade da liga de aluminio AA1050 partindo de placas obtidas por vazamento direto e bobinas obtidas por vazamento contínuo." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-12082010-172944/.
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A estampabilidade das ligas de alumínio é um assunto que interessa à vários segmentos industriais, pois é largamente aplicada na fabricação de peças e componentes. Entre dois processos de solidificação do alumínio, a solidificação de placa (DC) e o vazamento contínuo via caster (CC), o processo caster apresenta um histórico de condições inferiores para estampagens mais críticas nestas ligas. Este estudo visa avaliar as diferenças entre os processos de fabricação para chapas na liga AA1050 laminadas para 1,80mm, na condição recristalizada, durante a laminação e tratamento térmico e, caracterizar a microestrutura e textura. Ensaios de conformabilidade foram utilizados para identificar qual processo apresenta o melhor desempenho para estampagem. Para realização do estudo foram analisados três lotes de produção da Companhia Brasileira de Alumínio CBA, proveniente de processo de vazamento tipo placa (DC), e dois outros lotes provenientes de processo de vazamento tipo caster (CC) sendo, um com homogeneização intermediária e outro sem homogeneização. Os materiais foram processados em laminadores e fornos de escala industrial. A estrutura metalúrgica foi caracterizada através de ensaios metalográficos ao longo dos processos, obtendo-se a distribuição de intermetálicos e a estrutura cristalina através de microscopia ótica. A microscopia eletrônica também foi empregada para identificação dos precipitados. Ensaio de tração foi utilizado para identificar a variação das propriedades mecânicas ao longo do processo. Na condição final, ou seja, após laminação para 1,80mm de espessura com posterior recozimento foram utilizados os ensaios de orelhamento (earing), Erichsen, análise da anisotropia e levantamento da curva limite de conformação (CLC), para identificar qual processo apresenta o melhor resultado de conformação. A fim de entender as mudanças ocorridas nos materiais, foi estudada a macrotextura gerada no material ao longo da espessura da chapa. Na condição final foi realizada a microtextura no processo placa e caster sem homogeneização. A microestrutura dos materiais apresentou resultados distintos entre os processos, o material de placa mais homogêneo, tanto na distribuição dos intermetálicos quanto na estrutura granular. As propriedades mecânicas do caster, (LRT, LE e Dureza) ficaram um pouco superiores às do material de placa. O ensaio de Erichsen indicou que o material de placa resistiu a uma maior profundidade de conformação. No ensaio de orelhamento o caster sem homogeneização apresentou o menor índice, porém o material de placa apresentou a maior profundidade de conformação. As texturas encontradas ao longo dos processos foram principalmente a tipo Goss , Cubo e Cubo rodado . Também foram identificadas texturas típicas de cisalhamento após a laminação a frio, Dillamore {4 4 11} e Taylor {11 11 8}. A textura tipo S~ que é favorável a conformabilidade de metais CFC, apareceu ao final dos processos. Na curva limite de conformação (CLC) foi possível identificar que o caster com homogeneização apresentou o melhor resultado que os outros dois processos. Os ensaios de conformabilidade indicaram que o material de placa tem uma estampagem mais profunda, enquanto que o material de caster sem homogeneização tem um orelhamento menor.Stampability of aluminum alloys is a subject of interest to several industrial sectors because they are largely used in the fabrication of several parts and components. The choice is based upon the stampability and the relative manufacturing capability in relation to other aluminum alloys that contain larger amounts of alloying elements and, consequently, higher mechanical properties. When comparing two solidification processes, namely the direct chill (DC) and the continuous casting (CC) via caster, the CC process historically presents inferior performance for the more critical stampings in these alloys. This study aims at the evaluation of the differences between the fabrication processes (routes) of AA1050 rolled to 1,80mm sheets in the conditions as annealed, rolled and after heat treatment and to characterize their microstructure and texture. Stamping tests have been performed to identify which process presents best stamping performance. To carry out these studies three production lots from the Companhia Brasileira de Alumínio CBA have been employed namely one from the DC method and two other lots from the DC method, one with and one without an intermediate homogenization treatment. All materials have been processed in rolling mills and ovens in an industrial scale. The metallurgical structure has been characterized by optical and electronic microscopy throughout the processes analyzing the intermetallics and precipitate distribution. Tensile tests have been perfumed to identify the evolution of the mechanical properties throughout the process. In the final condition, i.e., after rolling down to 1,80mm and annealing, earing tests, Erichsen drawing tests and anisotropy have been evaluated together with the Forming Limit Diagram( FLD), to evaluate which process presented the best results in terms of formability. In order to understand the changes that occurred, the macrotexture has been studied along the thickness of the rolled sheets. In the final condition, the microtexture of the DC and the CC without homogenization have been compared. Different microstructures have been obtained for the studied processes: the DC material was more homogeneous, both in terms of intemetallic distribution and grain size. The mechanical properties of the CC material, in terms of TS, YS and hardness, were sligthly higher than those for the DC material. Erichsen test showed that the DC material takes higher deformations. Earing tests showed that the CC material without homogeneization presented the best results however the DC material presented better cup height. The textures analyzed for the different process stages were mainly of the Goss , Cube and rotated Cube types. Also some typical shear textures of the Dillamore {4 4 11} and Taylor {11 11 8} types have been observed in cold rolled sheets. The S~ type, which is favourable for the formability of FCC metals, showed up in the final processing stages. The FLD showed that the CC with homogenization presented better results when compared to the other two processing routes. The stamping tests showed that the DC material presents higher drawability while the CC material without homogenization presents lower earing index.
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ZAHEER, Omer. "RESHAPING AS NOVEL CIRCULAR ECONOMY STRATEGY FOR SHEET METAL BASED END-OF-LIFE COMPONENTS." Doctoral thesis, Università degli Studi di Palermo, 2022. http://hdl.handle.net/10447/533264.
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Making materials consumes about 21% of the global energy demand a specifically metals production, it accounts for about 8% of total global energy consumption. In fact, in the past few decades, the use of lightweight alloys has become increasingly widespread in many major industrial sectors thanks to the weight reduction associated with their applications. Most lightweight materials like aluminum alloys are characterized by high-energy demands primary production cycles that are responsible for a relevant share of the global CO2 emissions. Circular economy strategies such us longer life, more intense use, repair, product upgrades, modularity, remanufacturing, component re-use and open/closed loop recycling are strategies to put in place urgently to reduce the environmental impact. Although recycling of is metals the most used strategies and is being improved in terms of efficiency, it is mandatory moving towards more virtuous circular economy strategies, such us product/component reuse. A potentially effective strategy would be the incorporation of metal reuse techniques that would enable material recuperation at low environmental costs and in consequence, reducing the environmental impact of material production. Several researchers have bought forward strategies in response to the metal reuse question. In this dissertation, a novel reuse strategy for sheet metal-based End-of-life components is proposed. Specifically, a proposal towards the use of Single Point Incremental Forming for the Reshaping of End-of-Life sheet metal components has been presented. In particular, the suitability of this strategy as a circular economy enabler, has been studied with a particular focus on the technical feasibility of the SPIF process for the function of Reshaping, the quality of the end products of Reshaping and the energy efficiency along with the equivalent CO2 emissions of this strategy has been focused upon.
Dissertation Structure
Chapter 1, titled “Introduction”, deals with the general introduction to the metal recycling issues and capabilities, with particular focus on the lightweight alloys. The first subsection 1.1 introduces the concept of circular economy, followed by the metal reuse framework (section 1.2) which discusses the existing state of art on the various approaches proposed and studied in the past. Section 1.3 provides an introduction to the Single point Incremental forming process and it’s mechanics, followed by the proposed approach explained in section 1.4.
Chapter 2, titled “SPIF used as a Reshaper: Technical Feasibility”, contains the analysis of the technical feasibility of the proposed Reshaping strategy. Section 2.1 provides an introduction to the Deep Drawing process and technical aspects of the same. Section 2.2 details the procedure adopted, in terms of the experimental campaigns, and the results of analysis conducted. The discourse is then shifted towards the study of the effectiveness of Reshaping using conventional forming processes (section 2.3). The final sub-section of this chapter is a discussion of the overall outcome of the technical feasibility analysis and the direction towards which the research would focus after having obtained the said results (Section 2.4). The work presented in this chapter was published as:
1) Ingarao G, Zaheer O, Campanella D, Fratini L (2020) Re-forming end-of-life components through single point incremental forming. Manufacturing Letters, 24:132-135.
2) Zaheer O, Ingarao G, Di Lorenzo R, Fratini L (2021) On the effectiveness of SPIF process to re-form End-of-Life components as compared to conventional forming approach. SHEMET 2021.
Chapter 3, namely “Formability and Geometrical Accuracy Performances”, focuses on the analysis of the geometrical accuracy of the Reshaping technique. The first section 3.1 deals with the analysis of the geometrical accuracy of the End-of-Life component, in terms of the non-worked zones of the component during the Reshaping process. This research work was also focused on analyzing the effects of different process parameters (those of the original forming process, as well as, those of the Reshaping process) on the geometrical accuracy of the End-of-Life component. Section 3.2 was rather focused on the variation of the SPIF process formability when used as a Reshaper for different kinds of End-of-Life parts (Sheet metal components having different types of pre-strainings). Consequently, the geometrical accuracy of Reshaping pertaining to the different types of End-of-Life components was also analyzed in order to better understand the correlation between the pre-straining type/level and the obtainable geometry by SPIF. Finally, in section 3.3 the key findings of this chapter are summarized. The work presented in this chapter was published as:
1) Zaheer O, Ingarao G, Pirrotta A, Fratini L (2021) Geometrical deviation of end-of-life parts as a consequence of reshaping by single point incremental forming. International Journal of Advanced Manufacturing Technology, 115:1579-1588.
2) Zaheer O, Ingarao G, Di Lorenzo R, Fratini L (2021) Understanding formability and geometrical accuracy of SPIF process used as Reshaping approach. ESAFORM 2021.
Chapter 4, titled, “Energy Efficiency Analysis”, covers the performance of the Reshaping strategy in comparison to two other recycling techniques (Conventional and solid state recycling). This study was carried out in light of the overall energy consumption and the CO2 emissions relative to the entire process cycles. Section 4.1 covers the cumulative energy demand and CO2-emission analysis followed by the system boundary identification and assumptions. The energy demands and CO2 emissions of the three routes are compared to using experimental measurements of necessary data and LCI techniques in section 4.3. The results of these analysis and their relative discussions are elaborated in sections 4.4 and 4.5. This work presented in this chapter was published as:
1) Ingarao G, Zaheer O, Campanella D, Di Lorenzo R, Fratini L (2020) An energy efficiency analysis of single point incremental forming as an approach for sheet metal based component reuse. Procedia CIRP, 90:540-545.
2) Ingarao G, Zaheer O, Fratini L (2021) Manufacturing processes as material and energy efficiency strategies enablers: The case of Single Point Incremental Forming to reshape end-of-life metal components. CIRP Journal of Manufacturing Science and Technology, 32:145-153.
Chapter 5, titled “Reshaping by Hydroforming: Feasibility Analysis”, focuses on the studying the potential of carrying out the Reshaping strategy using an alternative forming process, i.e. Hydroforming. Section 5.1 cover the description of the designed experimental campaign and the technical parameters utilized. The results of this research (section 5.2) detail the key findings of the study and the influence of the process parameters on the process efficiency and quality of the obtained Reshaped components.
Chapter 6, titled “Conclusion”, provides a summary of the general results obtained for the entire research scope, highlighting the advances of the state of the art enabled by the research presented in this dissertation (section 5.1). Section 5.2 finally provides a general outlook of the investigated process, the milestones yet to be studied and a focus on the possible future developments of this work.
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Siqueira, Gonçalo. "Caracterização microestrutural, mecânica e tratamento térmico da liga AA-6082 obtida pelo processo de conformação por spray." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-16012013-093254/.
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O processo de conformação por spray é interessante devido à capacidade de conjugar, em apenas uma etapa do processo, a vantagem da técnica de solidificação rápida combinada com alta produtividade dos processos de fundição convencional. Este processo permite a obtenção de materiais livre de macrossegregações, livre de porosidades e com microestrutura refinada. A evolução recente das pesquisas está levando ao desenvolvimento de novas ligas e os resultados têm sido interessantes. O processo de solidificação rápida inerente da conformação por spray permite a produção de ligas com composições diferentes das obtidas pela fundição convencional. O objetivo deste trabalho foi o de caracterizar mecanicamente uma liga de alumínio AA-6082 conformada por spray. Os resultados de testes de dureza Vickers são apresentados para seções de um preformado em relação a sua altura (em um arranjo tridimensional). O material foi avaliado na condição como conformado por spray e após tratamento térmico de solubilização a 525 ºC por 1 h, seguido por envelhecimento a 125 ºC por períodos distintos de 1 h, 10 h, 100 h e 500 h. É mostrado que o a liga AA 6082 conformada por spray mostra uma boa estabilidade térmica em relação a variação da dureza durante o envelhecimento.The spray forming technology combines in a single step the advantages of the rapid solidification techniques and high the productivity of the conventional casting processes, allowing obtention of preforms with a refined microstructure, almost without porosity and macrosegregation free. The development and research efforts are leading to interesting alloys and materials production. The rapid solidification processes inherent to the spray forming allow the production of alloys with different compositions from those obtained by conventional ingot processes. The aim of this work was to carry out mechanical properties characterization of a spray formed AA-6082 alloy. The hardness results are presented in different sections related to the height of the spray formed preform (in a three-dimensional arrangement). The material was evaluated in the as sprayed condition and after heat treatment of solution at 525 ºC for 1 h, and aging for 1 h, 10 h, 100 h and 500 h periods. It was shown that the spray formed AA-6082 aluminum alloy is very stable regarding hardness variation during aging.
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Otani, Lucas Barcelos. "Solidificação da liga de alumínio 319 conformada por spray." Universidade Federal de São Carlos, 2017. https://repositorio.ufscar.br/handle/ufscar/8903.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
The main application of 319 aluminum alloy is for manufacturing components for automobile industry. One of the main concerns related to the recycling of this metal is regarding the incorporation of impurities as iron, for instance. Due to its low solubility in solid aluminum, the presence of this element leads to the formation of intermetallic compounds such as α-Al8Fe2Si and β-Al9Fe2Si2, the most common iron phases in Si-containing Al-alloys. The β phase is harmful to mechanical properties because of its platelet like morphology. Spray forming is an advanced processing technique which can mitigate the deleterious effect of these intermetallic phases. However, the solidification process of spray formed metals is still an open discussion. In these sense, the aim of this work is to contribute to a better understanding of the solidification process of spray formed 319 aluminum alloy. The work was divided in three stages: the first evaluated the presence and morphology of intermetallic phases by varying the pouring temperature and Fe content (0.6 and 1.2 in mass percent); the second evaluated the eutectic Al-Si morphology through varying the processing conditions; and finally, the third evaluated the solute distribution in the final microstructure, in this case other aluminum alloys were studied together with the 319 (2024 and 7050). The basis for discussion the phenomena was a solidification model for spray formed metals recently proposed in the literature, which defines the process in two stages, being the final solidification occurring at low cooling rate. The results showed that by controlling the processing parameters it is possible to mitigate the β-Al9Fe2Si2 formation, as well as to alter the eutectic Al-Si morphology. The third stage indicated the possibility of maintenance of certain solute in solid solution on the periphery of aluminum grains. It could be concluded that the solidification model was adequate to explain the phenomena presented in this work.
A liga de alumínio 319 possui como aplicação a fabricação de componentes da indústria automobilística. Um dos principais problemas relacionados à reciclagem destas ligas é a incorporação de impurezas como o ferro. Devido à baixa solubilidade deste elemento, sua presença leva a formação de compostos intermetálicos, sendo o α-Al8Fe2Si e o β-Al9Fe2Si2 os mais comuns em sistemas com silício. A fase β é a mais danosa às propriedades mecânicas devido à sua morfologia de placas, sendo que uma rota de processamento que se mostra viável no sentido de mitigação do efeito deletério deste intermetálico é a conformação por spray. Apesar disso, o processo de solidificação desta técnica ainda é um assunto debatido na comunidade científica. Neste contexto, este trabalho possui o objetivo de contribuir para um melhor entendimento sobre o processo de solidificação da liga de alumínio 319 conformada por spray. O trabalho foi dividido em três etapas: a primeira avaliou a presença dos intermetálicos de ferro variando-se a temperatura de vazamento e o teor de ferro (0,6% e 1,2% em peso); a segunda avaliou a morfologia do eutético Al-Si através das alterações das condições de spray; e, por fim, a terceira avaliou a distribuição de soluto na microestrutura, neste caso, outras ligas de alumínio foram estudadas (2024 e 7050). A discussão dos fenômenos foi realizada a partir de um modelo de solidificação para materiais conformados por spray que divide o processo em duas etapas distintas, sendo a solidificação final ocorrendo a uma taxa de resfriamento relativamente lenta. Os resultados mostraram que através do controle das condições de spray é possível mitigar a formação do intermetálico β-Al9Fe2Si2, assim como alterar a morfologia do eutético Al-Si. A terceira etapa indicou a manutenção de certos elementos em solução sólida em regiões adjacentes aos contornos de grão. Pôde-se concluir que o modelo de solidificação utilizado foi adequado para explicar os fenômenos descritos nas etapas realizadas.
CNPq: 135810/2015-9
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Plundrák, David. "Analýza příčin vzniku trhlin v ráfcích kol." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230459.
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This thesis looks for the causes of cracks in bicycle rims in the most stressed areas (in places holes for wires). For this reason, in this work is the stress and strain analysis of a simple model of the rim to the working load is given and further the complete production process of the rim is described. As an experimental material were used rims from different producers of aluminum alloy EN AW 6061 and EN AW 6082 T6 temper, in which a crack started to spread. For assessment of rims materials the methods of optical spectroscopy, optical microscopy, scanning electron microscopy, Vickers hardness test were used and for finding another crack penetration test was performed. Based on the performed experiments bad design solution of rivets was found in the rim 1. Broken rivets initiated fatigue cracks. Material of rim 1 was alright. The other two rims were deficiencies in materials. For the rim 2 was a problem with coarse-grained recrystallized structure. The insufficiently rapid cooling for the rim 3 caused exclusion hardening phase (particularly copper phase) at grain boundaries. Moreover, the rim 3 is not cured to the required parameters. Aluminium alloys are an ideal material for bicycle rims. However, they require reliable design solutions and meeting the physical metallurgy, which lies in the knowledge and use of influences of chemical composition, forming and heat treatment on mechanical, chemical, physical and technological properties.
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Šíma, Vojtěch. "Výroba sendvičové závitové vložky objemovým tvářením." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-399339.
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The project elaborated in a frame of Master‘s degree branch M-STG focuses on the design of a technology of sandwich coil used for connecting the aircraft floor sandwich panels to the fuselage bulkheads. The product is made of a lightweight aluminium alloy AlMn1. Combined cold extrusion with upsetting of the flange was chosen as the most fitting technology due to the manufacturing requirements and production series size of 120 000 pieces per year. The component is manufactured from a block blank in three operations by a progressive forming machine TPM 8-A with a nominal force of 1000 kN from Šmeral Brno a.s. producer. Within the project, tools for the production of the part were designed and also technical calculations for individual operations and technical and economic evaluation of production were made. The price of the component is estimated to be at least CZK 7,33.
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Lätzer, Michael. "Füge- und Übertragungsverhalten torsionsbelasteter Stahl-Aluminium-Rändelpressverbindungen." Doctoral thesis, Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-200348.
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Die vorliegende Dissertation beschäftigt sich mit analytischen, numerischen und experimentellen Grundlagenuntersuchungen zum Füge- und zum Übertragungsverhalten einer reibformschlüssigen Stahl-Aluminium-Rändelpressverbindung. Die Besonderheit dieser Verbindung besteht darin, dass eine mit einer Rändelung und Übermaß versehene harte Stahlwelle in eine weiche Aluminiumnabe mit kreisrunder Bohrung längseingepresst wird. Die maßgebende Größe für den Fügevorgang ist der Fasenwinkel der Welle φ. Der Nabenwerkstoff wird hierbei in Abhängigkeit des Fasenwinkels der Welle φ umgeformt beziehungsweise herausgeschnitten. Mit Hilfe der relativen Festigkeit R F , welche das Verhältnis von maximaler Lösekraft F l, max zu maximaler Fügekraft F f, max repräsentiert, wurde ein Gütekennwert zur gezielten Auswahl von Stahl-Aluminium-Rändelpressverbindungen hinsichtlich der axialen Übertragungsfähigkeit abgeleitet. Die Charakterisierung der experimentell ermittelten Torsionsmoment - Verdrehwinkel - Kurven ergab zur Auslegung die Bereiche Auslegungs- und Versagenskriterium. Das maximal übertragbare Torsionsmoment wird beim sogenannten Versagenskriterium τ S durch das Abscheren der Rändel in der Nabe erreicht. In Analogie zum Füge- und zum Löseverhalten zeigt sich der positive Einfluss des Fasenwinkels φ auf das übertragbare Torsionsmoment. So können formend gefügte Stahl-Aluminium- Rändelpressverbindungen ein um bis zu ca. 40% größeres statisches Torsionsmoment als vergleichbare schneidend gefügte Rändelpressverbindungen übertragen. Das mechanisch-physikalische Berechnungsmodell zur Berechnung des statisch übertragbarenTorsionsmomentes basiert auf der Kerbzahnverbindung. Damit kann das Torsionsmoment am Auslegungskriterium T pF sowie das maximal übertragbare Torsionsmoment bei Abscherung Tτ S ermittelt werden. Die Berücksichtigung des formenden beziehungsweise schneidenden Fügevorgangs wird in Abhängigkeit des Fasenwinkels φ mit Hilfe des sogenannten winkelbasierten Umformgrades ε plRPV beschriebenThe present thesis provides analytical, numerical and experimental fundamental studies for the joining behaviour and the transmission behaviour of a friction and form closure steel-aluminum knurled interference fit. The special feature of this connection is a knurled and oversize hard steel shaft, longitudinally pressed in a soft aluminum hub with a circular bore. The most important parameter for the joining process is the shaft chamfer angle φ. Due to the shaft chamfer angle φ the material of the hub will be formed or cutted during the joining process. By using the relative strength, the quotient of push out force and joining force who describes the joint strength, a first quality parameter for a precise selection of steel-aluminum knurled interference fit has been derived. The description of the experimentally determined torque - twisting angle – curves has shown areas of design criterion and mechanical breakdown. The maximum transmittable torque is achieved by reaching the shearing stress of the knurls in the hub - mechanical breakdown τ S. Similar to the joining and the push out behaviour, the positive influence of the shaft chamfer angle φ is also shown at the transmittable torque. Furthermore, knurled interference fits joined by forming can transmit higher torques of about 40% than interference fits joined by cutting due to the material hardening. The mechanical-physical model for calculating the static transmittable torque is based on the serration connection. Thus, the torque at the design criterion and the maximum transmittable torque at the mechanical breakdown can be found. The consideration of the forming or cutting joining process is described as a function of the shaft chamfer angle φ using the so-called angle-based plastic strain ε plRPV
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Lätzer, Michael. "Füge- und Übertragungsverhalten torsionsbelasteter Stahl-Aluminium-Rändelpressverbindungen." Doctoral thesis, Universitätsverlag der Technischen Universität Chemnitz, 2015. https://monarch.qucosa.de/id/qucosa%3A20428.
Full textAbstract:
Die vorliegende Dissertation beschäftigt sich mit analytischen, numerischen und experimentellen Grundlagenuntersuchungen zum Füge- und zum Übertragungsverhalten einer reibformschlüssigen Stahl-Aluminium-Rändelpressverbindung. Die Besonderheit dieser Verbindung besteht darin, dass eine mit einer Rändelung und Übermaß versehene harte Stahlwelle in eine weiche Aluminiumnabe mit kreisrunder Bohrung längseingepresst wird. Die maßgebende Größe für den Fügevorgang ist der Fasenwinkel der Welle φ. Der Nabenwerkstoff wird hierbei in Abhängigkeit des Fasenwinkels der Welle φ umgeformt beziehungsweise herausgeschnitten. Mit Hilfe der relativen Festigkeit R F , welche das Verhältnis von maximaler Lösekraft F l, max zu maximaler Fügekraft F f, max repräsentiert, wurde ein Gütekennwert zur gezielten Auswahl von Stahl-Aluminium-Rändelpressverbindungen hinsichtlich der axialen Übertragungsfähigkeit abgeleitet.
Die Charakterisierung der experimentell ermittelten Torsionsmoment - Verdrehwinkel - Kurven ergab zur Auslegung die Bereiche Auslegungs- und Versagenskriterium. Das maximal übertragbare Torsionsmoment wird beim sogenannten Versagenskriterium τ S durch das Abscheren der Rändel in der Nabe erreicht. In Analogie zum Füge- und zum Löseverhalten zeigt sich der positive Einfluss des Fasenwinkels φ auf das übertragbare Torsionsmoment. So können formend gefügte Stahl-Aluminium- Rändelpressverbindungen ein um bis zu ca. 40% größeres statisches Torsionsmoment als vergleichbare schneidend gefügte Rändelpressverbindungen übertragen.
Das mechanisch-physikalische Berechnungsmodell zur Berechnung des statisch übertragbarenTorsionsmomentes basiert auf der Kerbzahnverbindung. Damit kann das Torsionsmoment am Auslegungskriterium T pF sowie das maximal übertragbare Torsionsmoment bei Abscherung Tτ S ermittelt werden. Die Berücksichtigung des formenden beziehungsweise schneidenden Fügevorgangs wird in Abhängigkeit des Fasenwinkels φ mit Hilfe des sogenannten winkelbasierten Umformgrades ε plRPV beschrieben.The present thesis provides analytical, numerical and experimental fundamental studies for the joining behaviour and the transmission behaviour of a friction and form closure steel-aluminum knurled interference fit. The special feature of this connection is a knurled and oversize hard steel shaft, longitudinally pressed in a soft aluminum hub with a circular bore. The most important parameter for the joining process is the shaft chamfer angle φ. Due to the shaft chamfer angle φ the material of the hub will be formed or cutted during the joining process. By using the relative strength, the quotient of push out force and joining force who describes the joint strength, a first quality parameter for a precise selection of steel-aluminum knurled interference fit has been derived. The description of the experimentally determined torque - twisting angle – curves has shown areas of design criterion and mechanical breakdown. The maximum transmittable torque is achieved by reaching the shearing stress of the knurls in the hub - mechanical breakdown τ S. Similar to the joining and the push out behaviour, the positive influence of the shaft chamfer angle φ is also shown at the transmittable torque. Furthermore, knurled interference fits joined by forming can transmit higher torques of about 40% than interference fits joined by cutting due to the material hardening. The mechanical-physical model for calculating the static transmittable torque is based on the serration connection. Thus, the torque at the design criterion and the maximum transmittable torque at the mechanical breakdown can be found. The consideration of the forming or cutting joining process is described as a function of the shaft chamfer angle φ using the so-called angle-based plastic strain ε plRPV.
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恵子, 名取, and Keiko Natori. "微細複合組織金属の変形機構および塑性加工性に関する研究." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB12867122/?lang=0, 2014. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB12867122/?lang=0.
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ヘテロ構造組織を有する鉄・非鉄金属の組織形態に注目して,微視的構造やその挙動が巨視的現象(変形特性,成形性)として発現するメカニズムを解明することを目的とした.鉄系金属ではDual Phase型高張力鋼のスプリングバック現象のひずみ速度依存性,非鉄系金属では半凝固鋳造法と強ひずみ加工を組み合わせた亜共晶アルミニウム合金の衝撃後方押出し成形性に注目した.これらの検討によりいずれの試料においても,結晶粒界よりもスケールの大きいヘテロ構造に由来した変形機構が支配的であることが明らかになった.博士(工学)
Doctor of Philosophy in Engineering
同志社大学
Doshisha University
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Imbert, Boyd Jose Miguel Segundo. "Hybrid Electromagnetic Forming of Aluminum Alloy Sheet." Thesis, 2010. http://hdl.handle.net/10012/5517.
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Electromagnetic (EM) forming is a high-speed forming process that uses the forces induced on a conductive workpiece by a transient high frequency current to form the workpiece into a desired shape. This thesis presents the results of an experimental and numerical study carried out to determine whether an EM forming process could be used to sharpen the radius of part pre-formed using a stamping process. Two processes were studied; a single step EM forming operation and a “hybrid forming” operation consisting of a conventional pre-forming step and an EM corner fill, both considering aluminum alloy AA 5754. The single step EM process proved unable to form acceptable samples due to excessive sample distortion, but was used to gain insight into the EM forming process. The hybrid operation consisted of pre-forming 1 mm AA 5754 sheet into a v-shape with a 20 mm outer radius using a conventional stamping operation and then reducing or “sharpening” the radius to 5 mm using EM forming. Sharpening the radius to 5 mm using conventional stamping was not achievable. The hybrid operation proved successful in forming the 5 mm radius, thus demonstrating that the material could be formed beyond its conventional formability limit using the hybrid operation. Numerical models were used to gain insight into the processes and the challenges involved in their numerical simulation. The numerical simulations showed that EM corner fill operation produces very high strain rates (10,000- 100,000 s-1) and complex three dimensional stress and strain states. The effect of the high strain rates could not be properly assessed, since no constitutive data was available for such high strain rates. The predicted stress states show that the process was not plane stress and that large through-thickness compressive stresses are produced that are favorable to damage suppression and through-thickness shear strains that increase ductility. The high strain rates and the complex stress and strain states are considered the likely causes for the observed increase in formability. The models provided valuable insight, but did not predict the final shape exactly and the possible reasons behind this are analyzed. The research indicates that features that are not achievable using traditional stamping techniques can be obtained with the hybrid EM forming process.
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Hung, Jung-Chung, and 洪榮崇. "Frictional Effect on Ultrasonic-Vibration Forming of Aluminum Alloy." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/43228314505357372958.
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博士國立交通大學
機械工程系所
94
The purpose of this dissertation is to investigate the frictional effect of ultrasonic-vibration during forming of aluminum alloy. This study analyses ultrasonic-vibration drawing and ultrasonic-vibration upsetting, which are extreme cases to each other in terms of relative speed between die and workpiece, to explore the frictional effect of superimposing ultrasonic-vibration during forming processes. The study focuses on four subjects: the set up of an ultrasonic vibration hot upsetting system, the influence of ultrasonic-vibration on hot upsetting, the frictional effect of ultrasonic -vibration during upsetting, and the experiment and simulation of ultrasonic-vibration drawing. In this study, a cooling mechanism was used on an ultrasonic vibration hot upsetting system to overcome high-temperature forming difficulty at the beginning. The effects of ultrasonic-vibration on the upsetting of aluminum alloy was then explored using this system. Results show that the ultrasonic-vibration can significantly reduce the compression force during hot upsetting and the reducing effect of compression force decreases while the temperature increases. Furthermore, upsetting process was used to explore the frictional effect by superimposing an ultrasonic-vibration parallel to the direction of forming. Experimental results of extrapolated compression test also indicate that ultrasonic-vibration can reduce the compressive force when friction is eliminated. The consecutive results of the hot ring compression test and temperature measurements during ultrasonic-vibration on upsetting reveal that increasing temperature by ultrasonic–vibration may reduce the flow stress and increase the interfacial friction. Finally, The ultrasonic-vibration drawing experiments and finite element analysis were performed for CD, AUD and RUD to explore the relative speed effect of workpiece and die by superimposing ultrasonic-vibration parallel as well as perpendicular to the relative speed. For both AUD and RUD, the drawing force fluctuated with the die vibration when drawing speed was below the critical drawing speed and the fluctuation amplitude tended to increase with the decrease of drawing speed. When drawing speed reaches a critical value, the fluctuation of drawing force disappears. On the other hand, results reveal that the critical drawing speed of RUD is higher than AUD and the frictional effect of ultrasonic-vibration vanishes when the interfacial gap speed is zero. From above studies we may conclude that the frictional effect induced by ultrasonic-vibration should associate with both the effect of interfacial gap variation and the temperature increase in general forming processes. The weighting of these two effects depends on the type of forming process. Following this qualitative study, quantitative analysis on the frictional effects of ultrasonic-vibration will be proceeded in the future to be applied in practical forming processes.
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邱六舍. "Superplastic forming and diffusion bonding of 7475 aluminum alloy." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/23217612922964165003.
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LIN, JEN-HAO, and 林仁豪. "Stamping Assisted Quick Plastic Forming of AA5083-O Aluminum Alloy." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/swcyn8.
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碩士國立中央大學
機械工程學系
107
In general, the conventional superplastic molding process, because the molding takes too long, leads to non-economic benefits, and in order to find a better process method to solve this problem, this paper proposes for Quick Plastic Forming (Quick Plastic Forming, QPF) 's process, coupled with the idea of pre-punching-assisted preforming for metal phone casing molding, is expected to shorten the time required for this process and break through to become a more economical process. This study uses general commercial AA5083 -O Aluminum quick phone shell molding blown to blown molded plastic Fast explore, compare and analyzethe pre-stamped added auxiliary blowing plus pre-press and generally no faster assisted molding process capability, making phone analyzes whether more on the edge of the shell. The results of the study show that there is a rapid plastic forming using pre-punching, because a shape close to the finished product has been pre-punched, and then blown, which saves the time required and does not require a stepped blowing pressure. Blowing out the finished product we need is more time-optimized than the fast plastic molding without pre-punching aid.
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Fang-WeiLuo and 羅方韋. "Prediction of High-strain-rate Forming Limit of Aluminum Alloy under Electromagnetic Forming Process." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/50246079598292443835.
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碩士國立成功大學
機械工程學系碩博士班
98
A great deal of effort has been made on investigating fracture behaviors of metal sheets. With knowing the fracture behaviors, engineers are able to predict the occurrence of fracture and to prevent the sheet from fracture. With the development of high speed forming, formability theory and Cockcroft-Latham (CL) fracture criterion, which have been developed in quasi-static state, have been applied to predict fracture at high strain rate up to 1000 (1/s). In this work, the EMF experiment, which can deform a sheet at high strain-rates, was used for investigating the forming limit. The EMF experiment was performed by electromagnetically launching an aluminum alloy Al5052-H32 sheet of 0.5 mm thickness at a punch with a flat spiral electromagnetic coil. The punch was impacted by the sheets of different shapes in order to obtain forming limits at different strain paths. On the other hand, the punch radius was varied to generate various strain values of the sheet. Then, with the help of iteration analysis, the iterated effective stress – effective strain curve (ESESC) of the sheet was obtained. The obtained ESESC can be used to construct Johnson-Cook flow stress model. To predict the forming limit at high strain-rates, Cockcroft-Latham criterion was constructed using the obtained flow stress model. The results of simulation and fracture prediction at high strain-rates were both compared with the experimental results. The proposed experimental design was confirmed to be suitable for constructing the forming limit data of sheet at high strain rate up to 5000 (1/s).
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Lee, John Thomas. "Simulation and experimental investigation of hot forming of aluminum alloy AA5182 with application towards warm forming." Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-05-5743.
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This study focuses on hot and warm forming properties of aluminum alloy AA5182 sheet, with attention toward warm forming, by using gas pressure to form sheet material. A temperature range of 300°C to 450°C and a pressure range of 690 kPa (100 psi) to 2410 kPa (350 psi) were used in a test matrix of twenty one different test conditions for gas-pressure forming of a sheet into hemispherical dome in a gas-pressure bulge test. Multiple sets of tensile data were used to develop a material model that predicts the dome height and shape of an axisymmetric bulge specimen at any given time during forming. In simulations of the forming process, 17 simulations of the total 21 experimental conditions showed good agreement with the experimentally measured dome heights throughout forming tests. The four cases that did not show good agreement between simulation and experiment are a result of strain-hardening in the material during forming. Strain hardening was not significant in tension testing of specimens and was not accounted for in the material model, which considered only strain rates slower than for these experimental bulge testing. This demonstrates an effect which must be considered in future simulations to predict forming approaching warm conditions.
Two experimental bulge specimens were cross-sectioned post forming and grain sizes were measured to determine if grain growth occurred during the forming process. Experimental bulge specimens show no grain growth during the forming process. The tensile specimens from which the material model data were taken were measured to determine if plastic anisotropy was a possible issue. All specimens measured were proved to have deformed nearly isotropically. The results of this study show that predicting warm and hot forming of aluminum alloy AA5182 using gas pressure is possible, but that a more complex material model will be required for accurate predictions of warm forming. This is a very important step toward making hot and warm forming commercially viable mass production techniques.text
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Lin, Che-sheng, and 林哲聖. "A Study of Press Forming Properties of Multi-Layers Aluminum Alloy." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/x63nc2.
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碩士中州科技大學
機械與自動化工程系
105
In this experiment, the 3003-4343 aluminum alloy clad plate as the mainmaterial used mainly in the industry, pressing it to nature to do research, toSolidWorks, AutoCad of stamping die for accuracy, size mould. Optimization design, in order to reduce production costs for materials and achieving economic production, increase industrial competitiveness, this experiment through to the software design of mold, take this understanding material the size of the essence for compaction.Degrees the influence of small amounts of products, production can provide the industry in the future, material selection of reference. In this experiment, mainly to discuss an extension of the material properties, and its mechanical properties of material, combined with appropriate design for mold development. The first project must be used for cutting materials like engineering, which are equipped with forming the second. First of all will be The shear on the edge in materials processing, and after commenced through the theoretical formula to calculate the size, and to 45 tons of single axis (see adobe) or rammed the workpiece the completion, forming machine for stamping process, using Vernier Caliper with to do the work of height and made measurement and analysis and numerical method, using 2 D video and statistics, measurement instrument section to confirm for speed, to understand the pressure washed and cut section of the situation and feet to make their products can be accurate.Dimension accuracy requirement. and geometric shapes. Based on the results of comprehensive experiment and observation, combined with the theory and knowledge of materials, the processing conditions of economic benefit and suitable materials are designed.
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Chuen-Jiunn, Shyu, and 徐春濬. "Study on the Superplastic Forming of 8090 and 7475 Aluminum Alloy." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/46597670493859187375.
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Wang, Yu-Ying, and 王友穎. "Age-Forming of Aluminum Alloy Panel Containing Ribs in an Autoclave." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/81330364003282463318.
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碩士逢甲大學
機械工程學所
91
The traditional method of assembling big-size aircraft-wing specimens is to rivet wing skins, ribs, and spars after separately metal forming the skins and ribs. However, this manufacturing processing suffers time-consuming, residual stresses, fits problem and probability of damage. After the progress of computer-aided design technology, the light-weigh structure with high-stiffness can be obtained. Based on the precision predict of computer-aided analysis, some traditional manufacturing methods may be abruptly changed. The purpose of this thesis is to study the aging forming of an-isogrid panel. Age forming is a metal forming method that utilizes the metallurgical stress relaxation phenomenon that occurs during the artificial aging (heat treating) of metal. The study involves the computer-aided simulation on the determination of the contoured forming surface of the female forming tools and required pressures (the loading). The finite element based software ABAQUS is employed for the plastic forming simulation. The simulation also checks the probable local fracture of the ribs. Then, utilizing the thermal aging stress relaxation phenomenon, the milling panel with female forming tools are sealed by a vacuum bag and puts inside the autoclave for metal forming and heat treatment. The quantities of the springback of the panel after the release of pressure loading and heat treating are calculated. The influences of springback of the panel under different aging cycle conditions on the autoclave are also compared.
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Zhao, Chi-Hao, and 趙祈豪. "The Research on Quick Gas Forming in Precision of Aluminum Alloy." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/z4en7r.
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碩士國立中央大學
機械工程學系
106
This study uses a vernier caliper to measure the metal mobile phone back shell, and uses different measurement methods to measure the data, using quality management to assess the process capability is very important three indicators, namely the value of Ck (Capability of Accuracy), Cp value (Capability of Precision) and Cpk value (Capability of Process), Ck represents the accuracy of the process, Cp represents the precision of the process, and Cpk is the comprehensive process capability index. Through the above indicators to find out the standard deviation of the process, to analyze the practicality of this process, and as a reference for subsequent development.
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Yang, Yi-lang, and 楊益郎. "Friction and Lubrication Effect in Rapid Forming of Superplastic Aluminum Alloy 5083." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/64354997310633505818.
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Liu, Zong-Yu, and 劉宗諭. "The Effects of High Temperature Oxidation on 8090 Aluminum Alloy Superplastic Forming." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/39828596582801889271.
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碩士國立雲林科技大學
機械工程系
103
In this study, 8090 aluminum alloy set as research material to explore the impact on the formability of superplastic forming of the respond to the grain size, elongation and oxidation at different temperatures under atmospheric conditions. The material was heating constantly at different time and temperature. After heating, the thickness of high temperature oxidation production was observed through a scanning electron microscope. In addition, the elongation was measured to verify the deformation of superplastic forming sheet metal forming with high temperature tensile test. The results show that the microstructure of the 8090 aluminum alloy is heated at higher temperatures, the rate of oxidation is higher, the formability of the superplastic forming is also better at the higher temperatures. Keywords: superplastic forming, grain size, elongation, high temperature oxidation
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Bagheriasl, Reza. "Formability of Aluminum Alloy Sheet at Elevated Temperature." Thesis, 2012. http://hdl.handle.net/10012/7018.
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An experimental and numerical study of the isothermal and non-isothermal warm formability of an AA3003 aluminum alloy brazing sheet is presented. Forming limit diagrams were determined using warm limiting dome height (LDH) experiments with in situ strain measurement based on digital image correlation (DIC) techniques. Forming limit curves (FLCs) were developed at several temperature levels (room temperature, 100ºC, 200ºC, 250ºC, and 300ºC) and strain-rates (0.003, 0.018, and 0.1s-1). The formability experiments demonstrated that temperature has a significant effect on formability, whereas forming speed has a mild effect within the studied range. Elevating the temperature to 250C improved the formability more than 200% compared to room temperature forming, while forming at lower speeds increased the limiting strains by 10% and 17% at room temperature and 250ºC, respectively.
Non-isothermal deep draw experiments were developed considering an automotive heat exchanger plate. A parametric study of the effects of die temperature, punch speed, and blank holder force on the formability of the part was conducted. The introduction of non-isothermal conditions in which the punch is cooled and the flange region is heated to 250C resulted in a 61% increase in draw depth relative to room temperature forming.
In order to develop effective numerical models of warm forming processes, a constitutive model is proposed for aluminum alloy sheet to account for temperature and strain rate dependency, as well as plastic anisotropy. The model combines the Barlat YLD2000 yield criterion (Barlat et al., 2003) to capture sheet anisotropy and the Bergstrom (1982) hardening rule to account for temperature and strain rate dependency. Stress-strain curves for AA3003 aluminum alloy brazing sheet tested at elevated temperatures and a range of strain rates were used to fit the Bergstrom parameters, while measured R-values were used to fit the yield function parameters. The combined constitutive model was implemented within a user defined material subroutine that was linked to the LS-DYNA finite element code. Finite element models were developed based on the proposed material model and the results were compared with experimental data. Isothermal uniaxial tensile tests were simulated and the predicted responses were compared with measured data. The tensile test simulations accurately predicted material behaviour.
The user material subroutine and forming limit criteria were then applied to simulate the isothermal warm LDH tests, as well as isothermal and non-isothermal warm deep drawing experiments. Two deep draw geometries were considered, the heat exchanger plate experiments developed as part of this research and the 100 mm cylindrical cup draw experiments performed by McKinley et al. (2010). The strain distributions, punch forces and failure location predicted for all three forming operations were in good agreement with the experimental results. Using the warm forming limit curves, the models were able to accurately predict the punch depths to failure as well as the location of failure initiation for both the isothermal and non-isothermal deep draw operations.
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Hwan, Chang Ming, and 張明煥. "The Process Simulation and Fabrication Analysis of Superplastic Forming in 7475 Aluminum Alloy." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/19252611213517493529.
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Hsiao, Chia-liang, and 蕭家良. "The research of blow forming of aluminum alloy sheet for cell phone case." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/37590771705818080348.
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碩士國立中央大學
機械工程研究所碩士在職專班
100
In this study, we applied the blow molding process with the aluminum alloy AA5083 H18 material for the metal case of the cell phone products. Firstly, we use the superplastic forming machine to blow the rectangular opening box that similar to cell phone case. In recent years the trend of 3C products tend to be light, thin, short, small and variability, so It is the objective of this study the blow molding process applications on the mobile phone products, And it would need to achieve fast blow molding, small radius on the outline edge of the mobile phone products and 3D pattern appearance of the mobile phone product surface. Therefore, this study was started to experiment with the existing tooling hand-made plate. Firstly, the molding conditions are divided into two groups. One of group was fixed-forming temperature with the different molding pressure and time. Another group was fixed molding pressure and time with the different molding temperature. Base on the datum of the two groups to find out the relation by forming temperature, forming pressure, forming time, the radius of the outline surface and the fine line of the outline surface. Finally to apply the adjusted-forming condition we find with the vendor’s tooling plate to blow the finished product with fine line on the surface.
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Shiu, Feng-Ming, and 許峰銘. "The Analysis of Spinning Forming of Automobile’s Hub form 6061 Aluminum Alloy Billet." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/v4438f.
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碩士國立虎尾科技大學
創意工程與精密科技研究所
99
Hub is one of the important parts in the vehicle; it supports the vehicle weight, appearance, such an important role in steering and driving. As the automobile industry a tendency towards eco-car, comfort, safety, and energy saving which meaning the light weight design of automobile is more important. The wheel hub has a direct impact on the performance of the car''s lifetime, appearance, safety and comfort. The advantages of aluminum alloy wheels which is elegantly、highly strength, better heat dissipation, nature lightly, safely function and highly changeable external, less recycling cost all can drop the automobile oil consumption off. As the melting point is low which is easy to integrate all of the parts in the one and cover the parts quantities. It can reduce the automotive research and development and manufacturing cost. In view of the various factors, the aluminum alloy wheels have gradually replaced steel wheels. It symbolizes the high quality and also it’s widely used in the automotive industry. Spinning forming process is a complex process for an advanced manufacturing technology that has gradually applied to manufacture and produce in the automobile hub. To study and assay the spin forming process on the wheel which establishes a realistic mechanical model. To simulate the spin process which using DEFORM-3D to analysis aluminum alloy material of 6061. To analyze the variable area according to the metal flowing and plastic forming in spin process of the stress distribution. The reference data in accordance with taking shape and optimization of processing effectively.
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JIAN, ZIH-WUN, and 簡子文. "A Simulation Analysis of Aluminum Alloy A6061 on T-section Compression by Roll Forming." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/89965533774288345076.
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碩士國立高雄應用科技大學
模具工程系
104
For the purpose of simulated the process of plate on T-section compression by roll forming, the finite element software Deform 3D was used. The main selected material was A6061 aluminum which was most usually used for industry, setting up the reduction as fixed 10 percent on the protrusion at middle of the plate, and gradually increased the reduction on the side of plate by 15 percent, 20 percent, 25 percent and 30 percent. By the way of symmetric compression of same rollers radius roll forming when A6061 aluminum was used, investigated the influences during roll forming including the load on roller, width spread ratio and curvature of product by changing up parameters including thickness ratio of plate, gap width ratio of top roller, width of plate and coulomb friction coefficient, then according these results, then comparing with different materials including Brass-CDA-110 and SUS304 stainless steel that had different strength coefficient and hardening exponent. By the way of asymmetric compression of different radius rollers roll forming, investigate the influences during roll forming by changing up diameter ratio of rollers and coulomb friction on the plate contacting both top and bottom rollers. Finally, set reductions of plate fixed on middle for 10 percent and side for 20 percent, and investigated the influences of different coulomb friction coefficient and roller diameter for SUS304 stainless steel plate which had relatively highest strength coefficient and hardening exponent was between A6061 and Brass-CDA-110 on T-section compression by symmetric of same rollers radius roll forming. According to results from simulations of A6061 aluminum on T-section com-pression by symmetric of same rollers radius roll forming, when thickness ratio of plate and gap width ratio of the top roller increases, the curvature of product decreases, when coulomb friction coefficient and width of plate increases, the width spread ratio of product decreases. By the way of asymmetric of different rollers radius roll forming, when roller diameter ratio increased, the curvature of product trended to be flat. According to results from simulations of SUS304 stainless steel on T-section compression by symmetric of same rollers radius roll forming, when smaller diameter of roller was used and decreased coulomb friction coefficient, the product would adhere to bottom roller, even caused damages during the roll forming process.
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CHANG, YU-HSIEN, and 張育賢. "Study on Formability of Thin Sheet of Aluminum Alloy by Using Servo Forming Technology." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/8eqm34.
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碩士國立高雄科技大學
機械工程系
107
With the advancement of current process and manufacturing technology, the performance and the shape of the product gradually changed from a single profile and single function to a complex geometry and versatility. Taking multi-stage sheet metal forming as an example, it is easy to cause the material to springback after the various stages are formed, because the stroke of the equipment is fixed in the traditional process. In order to solve this problem, it is necessary to control the springback state of the material in the process with the shaping process, which not only causes the R&D cost to increase but also reduces the overall production capacity. In recent years, researchers have proposed an innovative forming method called servo forming, which can be formed with different kinds of punch motion curves under the fixed strokes (such as crank, hold, vibration motion curve etc.) to achieve stress relaxation. In this study, the results of servoformability were simulated by a small aluminum alloy cup, and the servo stamping curve with dead time and the dynamic hardening model with Simufact.Forming material were used in the servo forming curve. When the speed is stagnant for 60 seconds and the dynamic hardening parameter (γ) of the material is 8, the best formability is obtained, which means that the combination of the parameters can obtain the best predictive cup height performance.
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Weng, Cheng-hsien, and 翁正諴. "Superplasticity Effect Demonstrated by Gas Forming Superplastic 5083 and non-Superplastic 5052 Aluminum Alloy." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/95706334888953043947.
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碩士國立中央大學
機械工程學系
102
This thesis focuses on using superplastic forming to manufacture the aluminum "Airplane Fairing Cover" used on an actual commercial airliner. General superplastic forming usually uses flat sheet to produce symmetrical and less depth-width shape contour, however, the complicated and non-symmetrical work pieces are rarely produced by using superplastic forming. The sheet contour deform is large when flat sheet do the bending process, because fairing cover forming mold have complex shape, high aspect-ratio and the mold V-shape is deeper than middle saddle zone. Finally, wrinkle phenomenon occur in the forming results, and it is occur inside the cutting line area (Ending Opposite Position, EOP) of the product. In order to get the best forming result (i.e. fairing cover) and solve this problem, several improvement are perform, such as: blow with different P-T curve conditions, different material and material thickness usage (AA5052 and SP5083) and reduce the depth of V-side by modify mold (by add pads to reduce the mold cost).
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Chiang, Chun-Hsien, and 江俊憲. "The study on microstructure and properties of spray forming and conventional casting AC9A aluminum alloy." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/84221230732713605494.
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碩士國立成功大學
材料科學及工程學系
88
Spray Forming Process is a rapidly solidified process; materials produced by this process have the characteristics of fine grains and slight segregations. High silicon hypereutectic Al-Si alloys have better wear resistance. During solidification, the primary silicon will be produced first, so these materials can be provided high wear behaviors with primary silicons. Materials using in present study are JIS-AC9A Aluminum alloy. In this study, we will compare the difference of microstructures and mechanical properties between Spray Forming Process (SFP) and Squeeze Casting (SC) materials. For the SFP materials, the primary silicon sizes will be smaller than SC materials and the segregation will be slighter, too. For the SFP materials, the micro hardness values (measured from matrix) will be higher than SC materials at any heat treatment conditions, but the macro hardness (including silicons and matrix) will have no significant difference. From the aging hardening curve and observation of over aging specimens, we can find obvious hardening phenomena and some precipitates, but from the analysis of XRD, there are not any diffraction peaks of precipitates. About fracture energy, the SFP materials can absorb higher energy than SC materials, which results from the difference of silicon particle appearance between SFP and SC materials. Finally, present study will discuss the behavior of silicon particle coarsening at semisolid state, and plot particle coarsening curve to be a reference for SFP materials during formation at semisolid state.
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Weng, Ching-Chung, and 翁清浚. "A Study of the Technology Development of Quick Plastic Forming (QPF) for Aluminum Alloy Sheet." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/64271465670580390439.
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碩士國立中央大學
機械工程學系在職專班
104
The technology of "Superplastic Forming" was used ripely in the aerospace industry for many years. However, it extended to the automotive industry but cannot application generally because its production is slow. At this time, a practical technology in foundation of superplastic forming was developed by U.S. General Motors and called " Quick Plastic Forming, QPF", as well as it was used successfully to the production process for automobile body parts with aluminum alloy. Fortunately "automotive body lightweight" is already the common trend of development by the automobile industry in various countries. The only way is that them are made by high-strength thin steel, aluminum alloy, composite or magnesium alloy. The latter two donot seem real, and the competitiveness of each of the first two should be inconclusive.So aluminum alloy among others has become the main options of materials for automobile body. The development of a viable forming technology for aluminum alloy is importance and cost-effectiveness relatively. Therefore, the important course and experience of technology development of QPF by U.S. General Motors is deserved to understanding and learning deeply. In view of the domestic academia or automobile industry does not research to QPF basically, wherefore the present study is based on this view and prepares for domestic possible requirement in the future. Through a large number of primary and secondary literature review mode, the development, technical features and important achievement of QPF are investigated and inductive analyzed. In addition to propose the suggests for future research direction, the present study expects to provide that domestic interested industries and following researchers deliberate and apply.
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YE, CHAN-HONG, and 葉展宏. "Study on Thickness Distribution and Spring Back Phenomena of Sheet-Bulk Forming for Aluminum Alloy." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/70220663549864595342.
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碩士國立高雄應用科技大學
機械工程系
105
With the improvement of process technology, Aluminum alloy is widely used in many industries. The function of aluminum alloy product gradually change to functional integration of product from a single function. It is important to study the formability and spring back phenomena of thick aluminum alloy sheet. In this study, we used Deform 3D and Simufact.forming to simulate the sheet-bulk forming for thick aluminum alloy sheet. Mesh convergence analysis was conducted to find the optimal element size. Thickness distribution and spring back phenomena of the rectangular blank with round corners feature at process one was also investigated. Simulation results were compared to scanning file based on spring back phenomena. The results are as follows: the optimal element size is 2 mm in the mesh convergence analysis. Compared to tetrahedral elements, solid-shell elements are suitable for analyzing sheet bulk metal forming process. Cross section near binder area of the x-axis and near quarter of keyboard of the y-axis area it has minimum spring back phenomena.
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李翰文. "A Study on the High Strenth Aluminum Alloy Produced by the Semi-solids Forming Method." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/63169778360559108396.
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Chang, Jung-Kuei 1975. "The effect of microstructure on cavitation during hot deformation in fine-grained AA5083 aluminum alloy sheet material." 2008. http://hdl.handle.net/2152/18230.
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Aluminum alloys are of great interest to the automobile industry for vehicle mass reduction, which improves vehicle performance and reduces emissions. Hot forming processes, such as superplastic forming (SPF) and quick-plastic forming (QPF) have been developed to take advantage of the improved formability of certain aluminum materials at elevated temperature. Commercial fine-grained aluminum alloy AA5083 sheet is the most commonly used material in the SPF and QPF forming processes. Hot formability of AA5083 is often limited by material cavitation during forming, which makes understanding and controlling cavitation an issue of primary importance for improving hot sheet forming processes. The thermomechanical processing history of AA5083 can strongly affect superplastic performance, causing variations in formability between material lots. These variations are closely related to microstructure, and intermetallic particles are prime suspects for controlling cavitation behavior. However, there has been little more than anecdotal evidence available that these particles nucleate or influence cavitation. Interactions between intermetallic particles and cavities were, thus, analyzed using both two-dimensional (2-D) and three-dimensional (3-D) microstructure characterization techniques. Analysis of 3-D microstructures from AA5083 specimens deformed under conditions similar to the SPF and QPF processes provide conclusive proof that cavities form at specific types of intermetallic particles. Differences in cavitation between materials deformed under the SPF and QPF processes result from differences in deformation mechanisms. These differences are illustrated by the formation of filaments on fracture surfaces of superplastically deformed AA5083 specimens, which have been characterized.text
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Chen, Jih-Hsing, and 陳日興. "Investigation on Computer-aided Evaluation of Forming Limit in Cold Forging of High Strength Aluminum Alloy." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/26681276113153251438.
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碩士國立成功大學
機械工程學系碩博士班
91
To investigate the fracture on the free surface in upsetting process, five different ductile fracture criteria are evaluated in this research. The evaluated criteria include equivalent stress, maximum tensile stress, normalized maximum tensile stress, void growth and coalescence, and hydrostatic stress. After the most adoptable fracture criterion being obtained, we can identify the billet fractured or not by this criterion. In this research, we used the limit strain data measured in the literature to evaluate the most adoptable fracture criterion. After the most adoptable fracture criterion being obtained, it is then used to create simulation model by the DEFORM-3D software to predict the forming limits under different process conditions. The simulation of cylinder compression for the Al-2017F alloy was performed in different friction conditions and height/diameter ratios. The evaluated results show that the Cockcroft and Latham ductile fracture criterion is the most suitable for the fracture prediction in upsetting process. From the simulated results, friction coefficient and the height/diameter ratio will not change the fracture locus. The suddenly change of friction coefficient during experiments will affect the strain path, thus affecting the formability of the billet. With the proposed method, the construction of the forming limit diagram (FLD) can be simplified by selecting proper ductile fracture criteria during finite element simulation and comparing the simulated result with a few experimental results. Thus, the identification of fracture during process parameter optimization can be made.
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CHENG, JEN-CHAN, and 鄭任展. "Study on the Production of 5083 Aluminum Alloy Mobile Phone Case by Quick Plastic Forming (QPF)." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/72t6ks.
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碩士國立中央大學
機械工程學系
107
The paper is based on Quick Plastic Forming (QPF), which is made of 5083 aluminum alloy and superplastic 5083 aluminum alloy to make metal mobile phone casing. The experimental research discusses the fastest time to blow different thickness AA5083 coffins and compare them. The differences between AA5083 and SPF5083 materials are observed and discussed in terms of microstructure. The differences between AA5083 general grain and SPF5083 fine-grained materials are discussed. The thickness and uniformity of the raw materials and processed materials are discussed in various mechanical properties. Size results to explore and evaluate the fastest and most efficient blowing time. The experiment is mainly divided into three parts, the first part is to discuss AA5083 aluminum alloy 0.8mm material, the second part is to discuss AA5083 aluminum alloy metal material 0.6mm material, the third part is to discuss AA5083 and SPF5083 aluminum alloy 0.9mm aluminum alloy metal material and integrate The effect of each part time on size and thickness uniformity.
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Yu-YiChu and 朱祐誼. "Study on High Strain Rate Process Characteristics and Flow Stress in Electromagnetic Forming of Aluminum Alloy Sheet." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/75159616791721868373.
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博士國立成功大學
機械工程學系碩博士班
101
Electromagnetic forming (EMF) is a high strain rate forming process which exhibits significant advantages, such as increasing the formability of material, improving the springback of aluminum alloy and mitigating the wrinkling occurred in the tube compression process. Because of the particular advantages, EMF achieves a better forming result for complicated geometry which is difficult to be formed by conventional forming processes. In this research, a free impact sheet forming experiment was designed to examine the influence of frequency on the acceleration and impacting velocity. Moreover, a novel separable field shaper design was proposed to assist the EMF process. The efficiency of the field shaper under different geometric parameters was evaluated through the combination of Taguchi method and 3D coupled simulation, which is performed by coupled mechanical and electromagnetic simulation software, LS-DYNA EM module. In the experiment, a high-speed camera was used to record the free flying process, from which the retrieved images were used to characterize the forming velocity. Additionally, based on the described experimental set-up, a simple novel method based on the iteration procedure was proposed to determine the flow stress curve of aluminum alloy 1100-O at high strain rates. Examining the analysis results, the frequency seems to have a more significant effect than the skin depth on electromagnetic forming. In the frequency range between 4 kHz and 11.3 kHz, the skin effect is not a critical parameter and can be neglected. For the field shaper design, the results denote that the slit feature determines the performance of a field shaper. Wider slits reduce the energy loss resulting from electromagnetic repulsion. In addition, with more components of a field shaper, the generated magnetic pressure will be distributed more evenly. Based on the analysis result of the non-symmetric edge effect, some guidelines for designing field shaper are proposed. In addition, using the determined flow stress curve to simulate the forming process, the simulated deformation performed good agreement with the experimental result, where the deviation of effective strain could be reduced from 17.9% to 6.74%. Besides, the effective strains reached in these high rate forming experiments exceed the effective strain at failure determined in a quasi-static tensile test. Under the strain rate of 2800 s-1, the AA 1100-O material could be deformed to effective strain of 0.56 without fracture.
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Wu, Hung-Chi, and 吳泓錡. "A crystal plasticity study on the effect of precipitation and warm forming of 6000 series aluminum alloy." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/8w28zc.
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碩士國立臺灣大學
土木工程學研究所
107
Lightweighting is an important technology trend in the automotive industry. To this end, aluminum alloys have now emerged as a strong candidate of lightweight materials for the industry. For 6000-series aluminum alloys, both microstructural controls and warm forming techniques are the key issues to be resolved in the automotive application. Crystal plasticity finite element method (CPFEM) that links slip activities with mechanical properties is a natural choice to study these issues. The objective of this study is to incorporate proper precipitate hardening and temperature effects into CPFEM. It is well-known that in the physical-based CPFEM (or implicit model), the effect of geometrically necessary dislocation (GND) is averaged in the constitutive law. This study also extends the implicit model with different precipitate geometries (aka, explicit model) and investigate their effects on texture and mechanical behavior. The constitutive model is implemented in Abaqus UMAT. Geometries of precipitate such as shape, size, distribution and volume fraction are considered by Dream.3D. In contrast with the implicit model, the local dislocation density, stress concentration and misorientation around precipitate can be predicted by the explicit model. Moreover, the activating slip systems are analyzed under various crystal orientations and types of precipitate. Finally, we apply CPFEM to study surface roughening effects and texture under plane stain tensile loading. We find that texture band causes surface roughening and higher temperature increases surface roughening effect. In addition, deformation incompatibility between precipitate and crystal limit grain rotation. A 6000 series aluminum alloy, AA6016-T4P, is analyzed under tensile loading. Dislocation density accumulated around precipitate and grain boundary was successfully predicted. Grain orientations after deformation are found to be preferable in <100>//RD.
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Zhang, Yi-zong, and 張益綜. "Zr-based and Zr-Cu based Glass-forming Films for Fatigue-property Improvements of 7075-T6 Aluminum Alloy." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/98008095198122246510.
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碩士國立中央大學
機械工程研究所
99
We proposed with the Zr-based and Zr-Cu based metallic glass thin film (MGTF) as promising coating for aluminum alloy fatigue property enhancement. According to the four-point-bending fatigue results, 7075-T6 aluminum alloy with a 200-nm-thick Zr-based MGTF improved its fatigue life cycle 22 times at a stress level of 250 MPa than the bare one. And the other fatigue life cycle of Zr-Cu based MGTF is further improved 44 times which ups to 107 cycles. The improvements of MGTF coating samples in fatigue limit were 235 MPa (56.7 % increase) and 250 MPa (66.7 % increase) for Zr-based and Zr-Cu based glass-forming film, respectively, and 150 MPa for uncoated sample. The films actually restrict the surface offsets and cracks propagating during the fatigue test. Zr-Cu based glass-forming film have better fatigue resistance than Zr-based MGTF, the fatigue life had improved by more than 2 times under a stress of 250 MPa, due to higher hardness and strength, better plasticity, thus it exhibits better improvement in fatigue property. A 50-nm-thick Titanium buffer layer between the film and the substrate was reported adhesion enhancement. The superior mechanical properties of MGTF, such as high strength and good bending ductility, coupled with good adhesion between the film and the substrate as well as the reduced surface roughness, and high compressive residual stress of the metallic film yield the fatigue property improvement of aluminum alloy. Thus demonstrating MGTF as promising coating materials for improving the fatigue properties of materials, and further applied to aerospace, automobile industry and bicycle manufacturing etc.
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Ming, Huang Sin, and 黃信銘. "Study on Gas Forming of Superplastic 5083 and non-Superplastic 5083 Aluminum Alloy Sheet for Cell Phone Shell." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/quqdyn.
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碩士國立中央大學
機械工程學系
106
This thesis focuses on the application of quick plastic forming (QPF) process to the molding of metal cellphone shell. The experiments used different type of commercial 5083 and superplastic 5083 aluminum alloy sheet to carry out cellphone shell quick plastic forming at different times. Through a variety of mechanical properties and formability tests, to discuss the advantages of the quick plastic forming process to produce a cellphone shell, and which kind of sheet are more suitable as material for the quick plastic forming of cellphone shell. The results show that the effect of one stage quick plastic forming on the complete forming is the design of the mold, rather than the mechanical properties of material, and the mechanical properties of material is not much difference before and after forming. Based on the above results, it can be inferred that in order to make cellphone shell efficiently using the quick plastic forming process in aspect of economy and time, commercial 5083 sheet is the better choose for material.
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Vanegas, Moller Ricardo. "Design and fabrication of an instrument to test the mechanical behavior of aluminum alloy sheets during high-temperature gas-pressure blow-forming." 2008. http://hdl.handle.net/2152/10498.
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Hydraulic bulge forming has been used as a method to determine the properties of sheet metal alloys in biaxial stretching at room temperature. Gas-pressure bulge forming alleviates the issues of using hydraulic fluids when the tests are conducted at high temperatures (above 200°C). Testing a sheet metal alloy by gas-pressure blow-forming (GPBF) under controlled temperature and pressure conditions requires an accurate and reliable mechanism that delivers repeatable results. It was the purpose of this work to design and implement such an instrument. This instrument should deliver real-time data for material displacement during forming, which can then be used to better understand material plastic response and formability. Four different subsystems within this mechanism must interact, but also have enough independence for analysis and for assembly purposes. The combined sub-systems produced a GPBF apparatus capable of forming a sheet aluminum alloy AA5182 with a thickness of 1.5 mm into a dome with a height nearly equal to its radius under a constant gas pressure as low as 40 psi at 450°C. This GPBF apparatus produced, for the first time, in-situ data for dome peak displacement during gas-pressure bulge forming of AA5182 sheet at 450°C.text
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Carvalheiro, Cátia Gomes. "Estudo numérico do retorno elástico torcional em componentes de geometria complexa." Master's thesis, 2021. http://hdl.handle.net/10316/96218.
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Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e TecnologiaDevido ao esforço constante em reduzir o peso dos veículos e atender à pressão da economia para que se aumente a sua segurança, os aços avançados de alta resistência e as ligas de alumínio estão a ganhar cada vez mais popularidade. A relação entre resistência e peso nestes materiais é muito superior quando comparada com outros materiais, enquanto a ductilidade é similar. No entanto, o elevado retorno elástico após a conformação plástica é uma das desvantagens destes materiais, comprometendo a qualidade do produto final. Para prever a ocorrência de defeitos durante o processo de estampagem e posteriormente fazer a sua correção têm sido desenvolvidas ferramentas de produção virtual, nomeadamente a simulação numérica com o método dos elementos finitos. Desta forma, uma previsão correta permite reduzir o ciclo de desenvolvimento das ferramentas de estampagem, fazendo compensação do retorno elástico sem ter se fazer vários ciclos experimentais de tentativa-erro, poupando tempo e dinheiro.Este estudo tem como objetivo realizar a análise numérica do retorno elástico torcional num componente de geometria complexa, recorrendo ao programa de elementos finitos DD3IMP. Este componente de estudo foi proposto pela organização da conferência NUMISHEET. A modelação do comportamento elasto-plastico do material da chapa utiliza uma vasta gama de dados experimentais fornecidos para o aço de alta resistência DP980 e uma liga de alumínio 6xxx. Para além do efeito do material da chapa no retorno elástico, analisa-se também o efeito de outros parâmetros como: (i) coeficiente de atrito; (ii) freio de retenção; (iii) módulo de elasticidade; (iv) lei de encruamento e (v) critério de plasticidade. A análise destes parâmetros é realizada com o auxílio da simulação numérica, nomeadamente fazendo variar cada um destes parâmetros de forma independente.Foram avaliados vários parâmetros, tais como a evolução da força do punção e do cerra-chapas, o escoamento da chapa, o retorno elástico e o retorno elástico torcional na parte superior do componente e em toda a geometria do componente. Após análise dos resultados concluiu-se que a liga de alumínio apresenta menor retorno elástico em comparação com o aço. Por outro lado, o parâmetro com maior impacto no retorno elástico é a presença do freio de retenção, i.e. o retorno elástico é significativamente reduzido quando se utiliza um freio de retenção. Por outro lado, a anisotropia plástica do material da chapa tem pouca importância para o retorno elástico.
As a result of the constant effort to reduce vehicle weight and meet the economic pressure to increase their safety, advanced high strength steels and aluminum alloys are gaining increasing popularity. The relationship between materials strength and weight is much higher when compared to other materials, while the ductility is similar. However, the high springback after forming is one of the disadvantages of these materials, compromising the quality of the final product due to shape deviation. To predict the occurrence of defects during the stamping process and subsequently correct them, virtual production tools were developed, namely a numerical simulation with the finite element method. In this way, a correct prediction allows to reduce the development cycle of the stamping tools, compensating for the springback without having to do several experimental trial-error cycles, saving time and money.This study aims to perform the numerical analysis of the torsional springback in a complex geometry component, using the finite element code DD3IMP. This component was proposed by the organization of the NUMISHEET conference. Modeling the elasto-plastic behavior of the sheet material uses a wide range of experimental data provided for DP980 steel and a 6xxx aluminum alloy. In addition to the effect of the sheet material on the springback, the effect of other parameters is also analyzed, such as: (i) friction coefficient; (ii) beads; (iii) modulus of elasticity; (iv) work hardening law and (v) yield criterion. The analysis of these parameters is carried out with the aid of numerical simulation, namely by changing each of these parameters independently.Various parameters were evaluated, such as the evolution of punch and blank holder force, sheet draw-in, springback and twist springback on top of the component and across the component geometry. It was concluded that the aluminum alloy has a lower springback compared to steel. On the other hand, the parameter with the largest impact on springback is the presence of beads, i.e. the springback is significantly reduced when using beads. On the other hand, the plastic anisotropy of the sheet material is of little importance on the springback.
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金武, 直幸, 眞. 小橋, and 博仁 平. "金属基複合材料の部分使用に適した固相接合・複合プロセスの開発." 1999. http://hdl.handle.net/2237/13076.
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金武, 直幸, 孝至 伊藤, 眞. 小橋, 秀男 佐野, and 俊勝 小池. "圧縮・せん断複合負荷による高機能軽金属粉末の組織制御成形法." 2002. http://hdl.handle.net/2237/13117.
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