The present study aims to explore flow behavior in the mold during centrifugal casting process by numerical simulations. The theoretical model comprises two groups of steady conservation equations of mass and momentum and the governing equations are solved numerically with k-£` turbulence model and iterative SIMPLE(Semi-Implicit for Pressure-Linked Equations) algorithm to determine the flow property. The numerical results indicate that the melt liquids of titanium compound metal flow near the walls in the high rotation rate. With the high rotation rate, the outflow velocity is rapid. The products depend on the flow of the melt liquids. The flow is rapid, the filled process is quick, and the temperature is uniform. But if the flow is slow, the temperature is not uniform in the filled process. Therefore, the products may result in faults. When the rotation rate is up to 50 rpm, the melt liquids flow near the walls with the affect of centrifugal force. The velocity is larger than the velocity with zero rotation rate . Thus the flow with rotation rate can help to fill quickly, and reduce the temperature loss.

Orientador: José Geraldo Trani Brandão / Banca: Fernando de Azevedo Silva / Banca: Paulo Cesar Ribeiro Quintairos / Resumo: Este estudo mostra as variáveis dinâmicas do processo de fundição centrífuga de cilindros de laminação, que são utilizados para realização de conformação em gaiolas de laminação. O objetivo desse estudo é analisar as principais variáveis dinâmicas do processo de fundição centrifugada de cilindros de laminação e estudar as relações entre estas variáveis. Os processos de fundição centrífuga podem ser classificados em fundição centrífuga vertical e horizontal. Para a fundição centrífuga vertical, são elaborados os envelope de carga de dois modelos de máquinas centrífugas verticais existentes na literatura, onde se consegue determinar o tipo de rolamento de apoio utilizado na máquina. Para a fundição centrífuga horizontal, são estudadas variáveis como rotação, razão G, "aspect ratio", espessura e vibração de uma amostra de aproximadamente 1.000 cilindros de ferro fundido, aço rápido e aço alto cromo. Desta amostra, verifica-se que a causa de sucateamento de parte dos cilindros não está ligada a adoção de variáveis dinâmicas incorretas no processo. Também é visto que diferentemente do alumínio, os cilindros de ferro fundido, aço rápido e aço alto cromo exigem maior rotação quanto maior a espessura da casca fundida. / Abstract: This paper shows the dynamic variable of centrifugal casting process of rolling mill rolls which are used to compress the metal in rolling mill process. The main goal is to analyze the main dynamic variable and to study its relation in the process. There are two type of centrifugal casting: horizontal and vertical. For the horizontal centrifugal casting, two load envelopes are done, being possible to determine the bearing model used on the vertical centrifugal casting machine. For the horizontal centrifugal casting, variable such as rotating, ratio G, aspect ratio, thickness and vibration are studied to a sample of 1,000 casting rolls made of casting iron, high speed steel and high chromium steel. From this sample, it is seen that the cause of scrapping is not related to incorrect adoption of dynamic variables in the process. It is also verified that differently from the aluminum, cast iron, high speed steel and high chrome steel rolls demand greater speed with the increasing the shell casting thickness. / Mestre

There is a wide range of applications for 3D printing technology with an additive manufacturing such as aerospace, automotive, marine and oil/gas, medical, consumer, electronics, building construction, and many others. There have been many pros and cons for 3D additive manufacturing. Even though 3D printing technology has many advantages: freedom to design and innovate without penalties, rapid iteration through design permutations, excellence mass customization, elimination of tolling, green manufacturing, minimal material wastes, energy efficiency, an enablement of personalized manufacturing. 3D additive manufacturing still has many disadvantages: unexpected pre- and post-processing requirement, high-end manufacturing, low speed for mass production, high thermal residual stress, and poor surface finish and dimensional accuracy, and many others. Especially, the issues for 3D additive manufacturing are on high cost for process and equipment for high-end manufacturing, low speed for mass production, high thermal residual stress, and poor surface finish and dimensional accuracy. In particular, it is relatively challenging to produce casting products with lattice or honeycomb shapes having sophisticated geometries. In spite of the scalable potential of periodic cellular metals to structural applications, the manufacturing methods of I∙AM Casting have been not actively explored nor fully understood. A few qualitative studies of I∙AM Casting has been reported. Recently, a sand casting of cellular structures was attempted, resulting in casting porosity and the sharp corners in the lattice structure of the cellular structural molds, a sharpness which prevent fluid-flow and causes undesired solidification, resulting in misrun casting defects. Research on the indirect AM methods has not been aggressively conducted due to the highly complex and multidisciplinary problems across the process – continuum modeling (thermal stress, flow, heat transfer, and water diffusion) with multiple materials (polymer, metals, and ceramic) for multiphase simulations – solid, liquid, and gas. As an initial step to fully understand the processing of I∙AM Casting, a quantitative study on I∙AM Casting is conducted in this work.

Thesis (M.S.)--University of Alabama at Birmingham, 2008. / Description based on contents viewed July 8, 2009; title from PDF t.p. Includes bibliographical references (p. 47).

Made available in DSpace on 2014-06-11T19:28:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-12-16Bitstream added on 2014-06-13T20:18:22Z : No. of bitstreams: 1 goncalves_cg_me_guara_parcial.pdf: 217661 bytes, checksum: c20902856040fbee187ead0ee3cb00b5 (MD5) Bitstreams deleted on 2015-06-25T13:01:15Z: goncalves_cg_me_guara_parcial.pdf,. Added 1 bitstream(s) on 2015-06-25T13:03:30Z : No. of bitstreams: 1 000679599_20151231.pdf: 217896 bytes, checksum: cf025ea71faace9e52cbc1051e6f88a1 (MD5) Bitstreams deleted on 2016-01-04T10:26:26Z: 000679599_20151231.pdf,. Added 1 bitstream(s) on 2016-01-04T10:28:17Z : No. of bitstreams: 1 000679599.pdf: 1039378 bytes, checksum: fb5a9506ef24ceed88e78978a6f9f073 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este estudo mostra as variáveis dinâmicas do processo de fundição centrífuga de cilindros de laminação, que são utilizados para realização de conformação em gaiolas de laminação. O objetivo desse estudo é analisar as principais variáveis dinâmicas do processo de fundição centrifugada de cilindros de laminação e estudar as relações entre estas variáveis. Os processos de fundição centrífuga podem ser classificados em fundição centrífuga vertical e horizontal. Para a fundição centrífuga vertical, são elaborados os envelope de carga de dois modelos de máquinas centrífugas verticais existentes na literatura, onde se consegue determinar o tipo de rolamento de apoio utilizado na máquina. Para a fundição centrífuga horizontal, são estudadas variáveis como rotação, razão G, “aspect ratio”, espessura e vibração de uma amostra de aproximadamente 1.000 cilindros de ferro fundido, aço rápido e aço alto cromo. Desta amostra, verifica-se que a causa de sucateamento de parte dos cilindros não está ligada a adoção de variáveis dinâmicas incorretas no processo. Também é visto que diferentemente do alumínio, os cilindros de ferro fundido, aço rápido e aço alto cromo exigem maior rotação quanto maior a espessura da casca fundida. / This paper shows the dynamic variable of centrifugal casting process of rolling mill rolls which are used to compress the metal in rolling mill process. The main goal is to analyze the main dynamic variable and to study its relation in the process. There are two type of centrifugal casting: horizontal and vertical. For the horizontal centrifugal casting, two load envelopes are done, being possible to determine the bearing model used on the vertical centrifugal casting machine. For the horizontal centrifugal casting, variable such as rotating, ratio G, aspect ratio, thickness and vibration are studied to a sample of 1,000 casting rolls made of casting iron, high speed steel and high chromium steel. From this sample, it is seen that the cause of scrapping is not related to incorrect adoption of dynamic variables in the process. It is also verified that differently from the aluminum, cast iron, high speed steel and high chrome steel rolls demand greater speed with the increasing the shell casting thickness.

This master’s thesis is focused on design of centrifugal casting machine. Thesis includes the sorting and description method of centrifugal casting with overview of available machines. Proposal of parameters of centrifugal casting machine is done. Thesis includes technical-economic review of projection proposal for main parts of the machine. Design parameters are calculated and plan of machine is done. Safety assessment of proposed of machine variant is done. 3D model and drawings are included in thesis.

The centrifugal casting process is a common method for manufacturing the tubes, etc. Due to its high temperature and invisible mold, it is really difficult to know the mechanism of molten steel inside the mold. It is important to know the mechanism of the molten steel inside mold, since it will help the manufacturer to know more accuracy of the flow of the molten steel so that it can work for improving the productivity and quality of the products. Casting funnel design is the designed by Åkers for their funnel which will result in different flow behavior. In thesis work, casting funnel design will be investigated so that it can make sure that the casting funnel design can affect the flow behavior of molten steel or not. Another method of changing the diameter of nozzle was also carried out and investigated with both simulation and experiment to changing flow behavior of molten steel. It will give Åkers alternative method for changing the flow behavior to liquid steel. The mechanism of solidification in centrifugal casting is also really important since it can give manufacturer the general view of solidification process. So solidification of centrifugal casting is also investigated in the thesis work.

As ligas de alumínio hipereutéticas fundidas por centrifugação apresentam a possibilidade de obtenção de um gradiente funcional de propriedades no material (Functionally Graded Material - FGM). Na fundição por centrifugação, os compostos menos densos tenderão a se concentrar no diâmetro interno de um tubo centrifugado. Como a massa específica do silício e do Mg2Si são menores do que a do alumínio, as partículas dessas fases tendem a concentrar-se na parede interna de tubos centrifugados. Em função disto, este estudo tem como objetivo dar uma contribuição ao entendimento dos mecanismos de migração das partículas de silício e de Mg2Si numa liga de alumínio hipereutética com 19% de silício e com adições de cobre e magnésio fundidas por centrifugação. Diante disto, foram obtidos tubos da liga Al-19%Si com adições de até 5% de cobre e 5% de magnésio por meio da fundição centrífuga numa rotação de 1700 rpm. A caracterização microestrutural em diversas regiões dos tubos centrifugados foi feita utilizando-se a microscopia óptica e eletrônica de varredura com sistema de análise de imagens. A fração das fases presentes e a dureza Vickers foram determinadas ao longo da parede do tubo em diversas posições de vazamento. A fundição centrífuga promove a segregação de partículas de silício primário e de Mg2Si, com massas específicas menores para a parede interna do tubo. Esta segregação é mais acentuada na região final de vazamento devido ao maior tempo de centrifugação até a solidificação. Uma retenção de partículas junto à parede externa do tubo ocorre em decorrência da mais elevada taxa de resfriamento da liga fundida em contato com a parede do molde mais frio. Esta retenção também foi maior na região do tubo de início de vazamento em relação à de final de vazamento. A adição de cobre intensificou a migração das partículas devido ao aumento da densidade do líquido. O aumento do teor de cobre na liga também inibiu a presença de dendritas de alumínio primário que ocorrem em grandes quantidades nas regiões centrais das paredes dos tubos centrifugados. O perfil de dureza ao longo da parede do tubo indicou um aumento de dureza relacionado diretamente à quantidade de partículas de silício (β) e Mg2Si. / A functionally gradient material, in terms of its properties, can be obtained with centrifugally cast hypereutectic aluminum alloys. In centrifugal casting, the less dense compounds tend to concentrate close to the inner wall of a centrifugally cast tube. Since the specific mass of silicon and Mg2Si are less than that of aluminum, particles of these phases tend to concentrate at the inner walls of centrifugally cast tubes. On the basis of this, the aim of this study was to contribute towards increased understanding of the mechanism of segregation of silicon and Mg2Si particles in a centrifugally cast hypereutectic aluminum - 19% silicon alloy to which copper and magnesium were added. Hence, tubes of Al-19%Si alloy with up to 5% copper and up to 5% magnesium were centrifugally cast at rotational speed of 1700 rpm. Microstructural examination of various regions of the centrifugally cast tubes was carried out using an optical microscope and a scanning electron microscope coupled to an image analyzer. The amount of phases that formed and the Vickers hardness were determined across the thickness of the tube at different positions. Centrifugal casting promotes segregation of primary silicon and Mg2Si particles, (with lower specific weights) towards the inner walls of the tube. This segregation was higher at regions that were last to be cast, and due to longer centrifugation until solidification. Retention of particles close to the outer wall of the tube took place due to higher cooling rate of the cast alloy in contact with the cold walls of the mold. This retention was also higher at regions of the tube that were cast first compared with those that were cast last. The addition of copper increased particle migration due to increase in density of the liquid. Increase in the amount of copper in the alloy also inhibited the presence of primary aluminum dendrites that form in large quantities at the central regions of centrifugally cast tube walls. The hardness profile along the tube wall indicated an increase in hardness and this is directly related to the quantity of (β) silicon and Mg2Si particles.

A fundição centrífuga é um importante processo de produção de tubos de ligas metálicas e de cilindros de laminação. A transferência de calor no metal durante a fundição centrífuga de tubos foi modelada matematicamente e o coeficiente de transferência de calor na interface metal-molde determinado em função do tempo utilizando a técnica da solução inversa. A solução inversa foi obtida a partir das curvas de resfriamento experimentais disponíveis na literatura para a fundição centrífuga de um tubo de ferro-fundido. O resultado da solução inversa mostrou, pela primeira vez, que o comportamento do coeficiente de transferência de calor na interface metal-molde durante a fundição centrífuga é semelhante ao da fundição estática: tem-se um valor elevado logo após o vazamento, apresentando um decréscimo exponencial com o tempo. Um modelo matemático da transferência de calor na interface metal-molde foi desenvolvido com base nos mecanismos fundamentais de transferência de calor, como a transferência por condução e radiação através do vão formado nesta interface. Para a previsão deste vão, foram considerados os efeitos da contração térmica e da deformação plástica da casca metálica solidificada. A utilização deste modelo matemático para a transferência de calor na interface metal-molde permitiu o cálculo de curvas de resfriamento em excelente aderência às curvas experimentais reportadas na literatura. / Centrifugal casting is an important process to produce metallic pipes in general and cylinders for steel rolling mills. A mathematical model was proposed for the heat transfer during solidification of centrifugally cast pipes. The heat transfer coefficient at the metal-mold interface was determined as a function of time by the inverse solution technique. The inverse solution was obtained using experimental cooling curves available in the literature for a centrifugally cast-iron pipe. The inverse solution showed, for the first time, that the behavior with time of the heat transfer coefficient at the metal-mold interface is analogous to that observed in traditional static casting processes: an initial relatively large value decreases exponentially with time. A mathematical model for the heat transfer at the metal-mold interface based on fundamental heat transfer principles was proposed. In this model, the heat conduction and radiation in the gap formed at the metal-mold interface, as well as the thermal and plastic deformation of the solid shell, were taken into account. This model, applied to predict the solidification of a cast-iron tube in the centrifugal casting process, enabled the calculation of cooling curves that are in excellent agreement with experimentally measured curves.

As ligas de alumínio hipereutéticas fundidas por centrifugação apresentam a possibilidade de obtenção de um gradiente funcional de propriedades no material (Functionally Graded Material - FGM). Na fundição por centrifugação, os compostos menos densos tenderão a se concentrar no diâmetro interno de um tubo centrifugado. Como a massa específica do silício e do Mg2Si são menores do que a do alumínio, as partículas dessas fases tendem a concentrar-se na parede interna de tubos centrifugados. Em função disto, este estudo tem como objetivo dar uma contribuição ao entendimento dos mecanismos de migração das partículas de silício e de Mg2Si numa liga de alumínio hipereutética com 19% de silício e com adições de cobre e magnésio fundidas por centrifugação. Diante disto, foram obtidos tubos da liga Al-19%Si com adições de até 5% de cobre e 5% de magnésio por meio da fundição centrífuga numa rotação de 1700 rpm. A caracterização microestrutural em diversas regiões dos tubos centrifugados foi feita utilizando-se a microscopia óptica e eletrônica de varredura com sistema de análise de imagens. A fração das fases presentes e a dureza Vickers foram determinadas ao longo da parede do tubo em diversas posições de vazamento. A fundição centrífuga promove a segregação de partículas de silício primário e de Mg2Si, com massas específicas menores para a parede interna do tubo. Esta segregação é mais acentuada na região final de vazamento devido ao maior tempo de centrifugação até a solidificação. Uma retenção de partículas junto à parede externa do tubo ocorre em decorrência da mais elevada taxa de resfriamento da liga fundida em contato com a parede do molde mais frio. Esta retenção também foi maior na região do tubo de início de vazamento em relação à de final de vazamento. A adição de cobre intensificou a migração das partículas devido ao aumento da densidade do líquido. O aumento do teor de cobre na liga também inibiu a presença de dendritas de alumínio primário que ocorrem em grandes quantidades nas regiões centrais das paredes dos tubos centrifugados. O perfil de dureza ao longo da parede do tubo indicou um aumento de dureza relacionado diretamente à quantidade de partículas de silício (β) e Mg2Si. / A functionally gradient material, in terms of its properties, can be obtained with centrifugally cast hypereutectic aluminum alloys. In centrifugal casting, the less dense compounds tend to concentrate close to the inner wall of a centrifugally cast tube. Since the specific mass of silicon and Mg2Si are less than that of aluminum, particles of these phases tend to concentrate at the inner walls of centrifugally cast tubes. On the basis of this, the aim of this study was to contribute towards increased understanding of the mechanism of segregation of silicon and Mg2Si particles in a centrifugally cast hypereutectic aluminum - 19% silicon alloy to which copper and magnesium were added. Hence, tubes of Al-19%Si alloy with up to 5% copper and up to 5% magnesium were centrifugally cast at rotational speed of 1700 rpm. Microstructural examination of various regions of the centrifugally cast tubes was carried out using an optical microscope and a scanning electron microscope coupled to an image analyzer. The amount of phases that formed and the Vickers hardness were determined across the thickness of the tube at different positions. Centrifugal casting promotes segregation of primary silicon and Mg2Si particles, (with lower specific weights) towards the inner walls of the tube. This segregation was higher at regions that were last to be cast, and due to longer centrifugation until solidification. Retention of particles close to the outer wall of the tube took place due to higher cooling rate of the cast alloy in contact with the cold walls of the mold. This retention was also higher at regions of the tube that were cast first compared with those that were cast last. The addition of copper increased particle migration due to increase in density of the liquid. Increase in the amount of copper in the alloy also inhibited the presence of primary aluminum dendrites that form in large quantities at the central regions of centrifugally cast tube walls. The hardness profile along the tube wall indicated an increase in hardness and this is directly related to the quantity of (β) silicon and Mg2Si particles.