Navegando por CNPq "CNPQ::ENGENHARIAS::ENGENHARIA MECANICA::PROCESSOS DE FABRICACAO"

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Acesso aberto (Open Access)
Análise da aplicação de modelagem e simulação computacioal como apoio à tomada de decisão em processos produtivos industriais: estudo de caso em uma organização do segmento de duas rodas
(Universidade Federal do Pará, 2011-02-28) NOGUEIRA, Reginaldo Alves; OLIVEIRA, Roberto Célio Limão de; http://lattes.cnpq.br/4497607460894318
This study aims to analyze the resources and advantages of using modeling and computer simulation in industrial manufacturing processes as a tool to support the decision making. Thus, a case study was made at a motorcycle company located in Manaus’ Industrial Center, in which they used the software Tecnomatix® Plant Simulation. Initially, it was developed a simulation project, based on the industrial manufacture of a productive process of the variable support, an important item on the motorcycles production. This manufacture is known for its high complexity, due to the risks during its productive process. This dissertation also presents concepts related to the production management and the importance of decision making as well as the main definitions of modeling and computer simulation, with emphasis on Plant Simulation platform. Some other advantageous applications of using the modeling and computer simulation as tools have been identified, as we wrote this dissertation. However, we would rather make a restriction and just demonstrate the optimization of a manual productive process. After analyzing the simulation’s results, in multiple virtually modeled scenarios, taking into consideration the risk and productivity parameters, as well as having a systemic understanding of the situation, we considered the best option to organize would be the automated productive scenarios whose layouts allow greater interaction, flexibility, productivity and lower risk - providing the maximization of the desired results. Finally, from the analysis of the achieved results, as well as the relevant conclusions, it is easier to see clearly the advantages and resources of applying computer simulation as a support tool on the decision making in industrial manufacture processes.
Acesso aberto (Open Access)
Análise da influência dos solutos Zr e Ti sobre as propriedades mecânica, elétrica e de termorresistência de uma liga Al-Cu-Fe-Si destinada a Tx e a Dx de energia elétrica
(Universidade Federal do Pará, 2012-01-10) MACHADO, Paulo Cordeiro; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290
The global energy context presents a steady increase in electricity consumption in the last century, thus requiring the search for new materials for use in wire and cable conductors of electricity. From these demands for new materials, was developed an analysis of the influence of solute titanium and zirconium in the modification of important characteristics of the Al-Cu-Fe-Si alloy, destined to be the middle conductor of electricity, aiming to get properties resistant to heat. For this study, the alloys were obtained by direct casting in Ushaped metal ingots, from the Al-EC, standing at the base levels of 0.05 wt% Cu, [0.24 to 0.28] wt% Fe and 0.7 wt% Si, and then inserting the contents of 0.26 wt% Zr and 0.26 wt% Ti. The experiments were, divided in two steps, STEP A and STEP B , respectively. In order to characterize mechanical, electrical and structure of alloys. The specimens after cold rolling (in diameters of 2.7, 3.0, 3.8 and 4.0 mm) were analyzed without heat treatment (STT) and with heat treatment (CTT): 230 °C for one hour, according to the protocol COPEL (Companhia Paranaense de Energia Elétrica), 310 °C and 390 °C for one hour, to evaluate the heat resistance at higher temperatures, thermal stability and analyze the microstructures developed in these heat treatments (TT). It was found that Ti has more capacity to refine the grain compared to Zr, which has less refined grains, but with better physical properties are presented and heat resistant.
Acesso aberto (Open Access)
Aspectos metalúrgicos de revestimentos em dutos depositados com a superliga de níquel ERNiCrMo-4 pelos processos MIG convencional e MIG com adição de arame frio
(Universidade Federal do Pará, 2012-08-02) SANTOS, Marcio Wagner Batista dos; MOTA, Carlos Alberto Mendes da; http://lattes.cnpq.br/2041034504642740
This work is a metallurgical analysis of the inner lining layer of pipeline used in welding process MIG C and MIG AF. The petrochemical industry, and others that use pipelines for transportation of their raw materials, faces a major challenge: how to increase the useful life of these products in a harsh environment work? In the specific case of the petrochemical industry, whom this research is directed, the pipes serve as means of transportation for oil and gas, products that are extremely aggressive to the internal walls of these tubes that are degraded by corrosion, caused mainly, by chemical composition, pressure and temperature these products. In this context the welding of lining made with nickel-based alloys becomes an excellent option for the construction, repair and maintenance of equipment whose application be returned in harsh environments of work, allowing the improvement of characteristics required, such as the resistance to corrosion. It is this scenario that emerges the theme for this research, based on studies that indicate that the process of welding MIG / MAG with the addition of cold wire, has to evaluate the metallurgical characteristics of the pipeline coating deposited by the derivative process MIG conventional – MIG-C and MIG with the addition of cold wire - MIG AF - using Nickel alloy ERNiCrMo-4 in carbon steel pipelines. The welds were deposited in pipes of 228.6 mm of diameter, forming a layer of internal lining of four passes, divided into three segments of the circumference of the duct, in three different welding energy: 1.1, 0.9 and 0.7 kJ / mm. These segments are removed specimens of the ducts, for the production of the samples. After metallography, performed on the samples, followed with the analysis and characterization by optical microscope, scanning electron microscope and testing of microhardness. The coatings exhibited excellent surface quality for all operational packages used in obtaining the welds. The results of the analysis of the regions studied: metal base, partially mixed zone and heat affected zone, were compatible with the literature studied for both the MIG with the addition of cold wire, as for the conventional. In HAZ were observed values of Tungsten around 1.0%, the increased levels of hardness was credited to this fact. The microhardness results indicated that in both cases, MIG C and MIG AF, in 4 regions analyzed occurred similarly, and the HAZ region which showed the highest values in the range 400-500 HV, while in the other regions range was between 250-350 HV. The results indicate that the process with cold wire, MIG AF, was as efficient as the conventional MIG C. The welding power increased the dilution of Fe in the weld metal. Precipitates rich in Mo and Cr were found in the weld metal.
Acesso aberto (Open Access)
Avaliação das propriedades mecânicas e elétricas da liga 6201 não refinada, modificada com os teores de cobre (0,05 e 0,3)% para transporte de energia elétrica
(Universidade Federal do Pará, 2009-03-27) VENTURA, Odila da Silva Passos; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290
At the present work, experiments were made with the unrefined alloy Al – 0,6%Mg - 0,8%Si, with variations in copper content (0,05% e 0,3%), that aimed to evaluate two aspects of the alloy behavior. The first aspect concerns the affinity between it and the mold, which seeks to observe the effect of the solidification thermal variables of the structure of molten and the correlation with mechanical and electrical properties, the second aspect is related with the intrinsic behavior of the variation on the chemical composition subject at low speed and cooling rates. For evaluating the solidification thermal variables (liquidus isotherms velocities, cooling rates) was used a device for horizontal unidirectional solidification. The ingots produced from the solidification of the alloy rose by mechanical machining, laminating and steel drawing, examined in different positions and diameters, by testing the traction and electric conductivity. Fractures were analyzed in terms of micro cavities and different levels of copper and it was found that in the cold deformed material, the limit of tensile strength has a trend of growth for the alloys of higher concentration of copper. The measured values have also concluded that the electrical conductivity increases the greater the diameter of the micro cavities and lower the copper content. In order to evaluate only the intrinsic variation behavior of the alloy chemical composition, a second device was used for solidification, mold in "U", painted internally in solution of kaolin that attaches to such low rates of cooling. The results show that for both copper content there is a tendency of increase in the limit of tensile strength with increasing reduction suffered by the samples, the limit of tensile strength greater for the alloy with higher copper content. We attach this behavior to the higher content of solute which in turn showed better response to plastic deformation, compressing the material. However, the electrical characterization occurs in an opposite way, as seen in unidirectional solidification, where the lowest copper content was more efficient.
Acesso aberto (Open Access)
Caracterização da liga 6101 refinada com a adição de diferentes teores de cobre e solidificadas em molde unidirecional horizontal e em molde "U"
(Universidade Federal do Pará, 2007) FEITOSA, Johnyson Pereira; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290
The 6101 alloy (series 6xxx) was modified with addition of 0.05% and 0.3% of copper and with additions of grain refiners as Al-Ti-B. The alloys were thermally characterized (heat transfer coefficient of metal / mold, displacement speed of liquidus isothermal and cooling rate), mechanically (tensile strength and toughness module) and electrically (electric resistivity, specific resistance and power conductivity) using two forms of pouring out: one is horizontal directional solidification and the other into the "U" mold. By horizontal directional solidification was possible characterize the macrostructure, influenced by refiners of grain and by viscosity that copper provides in the metal / mold efficiency of alloys researched, modifying the thermal, mechanical and electrical properties. The solidification in "U" mold makes possible evaluates the mechanical and electrical properties, seeing the forming process variables of alloys, as forming rate, tensile strength, toughness and electric resistivity, power conductivity and electric resistance, using the specimens obtained in several diameters. For the “U” mold were casting more two alloys to evaluation, Al-0,6Mg-0,4Si-0,1Cu and Al-0,6Mg-0,4Si-0,2Cu. The mechanical and electrical properties had been influenced by cold working, copper content and shrinkage void presents into alloys structures.
Acesso aberto (Open Access)
Caracterização microestrutural e de propriedades mecânicas de soldas do aço ASTM A 131 pelos processos FCAW convencional e com adição de arame frio
(Universidade Federal do Pará, 2011-09-23) RODRIGUES, Lino Alberto Soares; BRAGA, Eduardo de Magalhães; http://lattes.cnpq.br/4783553888547500
The work presented here show comparatively mechanical properties and microstructure of weld metals employing two welding techniques, an already disseminated, FCAW (arc welding with cored wire) and the other is innovative, FCAW-AF (arc welding with Adding Tubular Wire with a cold wire is not energized) at three levels of speed 6, 8 and 10 m / min. In this process two diameters of the cold wire 0.8 and 1.0 mm were used. The base metal used was a naval steel ASTM 131 grade A (low carbon) in geometry of plates 150 mm x 300 mm x 9.5 mm, applied to V-groove (Bisel of 22.5°) with angle 45° summed, with mild opening of root of 2.4 mm. The weld used was top type with the application of two passes, one root pass and the pass of finish (or filling). In order to establish of weld conditions 5 types of destructive were carried out: face transverse bend, tension, impact test (Charpy notched type V), microhardness and metallographic test. In addition to the non-destructive analysis visual and penetrating liquid. In general, the results for the process FCAW-CW, show themselves compatibles, regarding the process FCAW conventional, but some results showed smaller values of mechanical property. This fact much probably happened due the presence of discontinuities in the welded joint FCAW-CW. The microstructural characterization presented similar results to FCAW-CW and FCAW conventional for all energy levels studied.
Acesso aberto (Open Access)
Colagem de junta de madeira com adesivo epóxi
(Universidade Federal do Pará, 2010-02-08) CARNEIRO, Ruth Pereira; FUJIYAMA, Roberto Tetsuo; http://lattes.cnpq.br/3165747089941318
This work has as objective of making, to test and to compare the glued joints of butt, scarf and finger with three species of wood of different densities. The collage of the wood makes possible the use of pieces and surpluses of wood that are usually discarded, could minimize the cut of a lot of trees, be of the nature or of planned planting. The methodology of production of the joint, it was established with base in indications described in Brazilian norms. Macroscopic observation of the wood it was accomplished, for confirmation of your species. After established the dimension of the joints they were made bodies of proof, using the adhesive Compound Adhesive of epoxy base and wood Angelim-pedra, Jatobá and Tauari, acquired in wood deposit in the city of Ananindeua-Pa. With relationship the characterization of the adhesive, it was verified through the traction tests that has good mechanical resistance. After collages of the joints it was accomplished traction tests to determining the resistance of the glued joints. The glued joints performance it was evaluated in function of the relationship among the values of resistance to traction of the solid wood and the values of resistance to traction with glued wood and rupture way. In agreement with the results it was observed that the glued joints scarf they presented excellent resistance to traction, very close of the resistance of the solid wood; it was also noticed the good acceptance of collage of the wood Jatobá. With relationship the quality of the adhesion, the glued joints of butt and finger, therefore they presented adhesive rupture. The experimental results obtained indicate a good agreement among the theoretical models to evaluate the resistance to the traction and the qualification of the glued joints.
Acesso aberto (Open Access)
Comportamento mecânico de material compósito de matriz poliéster reforçado por sistema híbrido fibras naturais e resíduos da indústria madeireira
(Universidade Federal do Pará, 2008-02-29) RODRIGUES, Jean da Silva; FUJIYAMA, Roberto Tetsuo; http://lattes.cnpq.br/3165747089941318
In this work, composite materials of polyester matrix reinforced by short sisal fiber, by residue of wood and by hybrid system for sisal / residue of wood, arranged randomly, were produced using the minimum stages of technology processing in the productive step, with views to produce a composite material easy technically to produce. The polyester matrix used was a pre-accelerated tereftálica with cobalt naftenato and cured at room temperature with methyl ethyl ketone peroxide (MEK) in different proportions in relation to the resin, 0.33%, 1.66%, 3.33% and 5.00% by volume in order to evaluate the influence on mechanical properties. The sisal fibers were manually cut in lengths of 5, 10 and 15 mm and used in the way purchased and surface untreated. The residue of wood powder was used of maçaranduba wood. The composites were produced by manual moulding, without pressure and room temperature. Specimen were manufactured for evaluated matrix, composites reinforced by sisal, ranging of the length of the fibres, composites reinforced by maçaranduba residue and strengthening of hybrid composites, sisal / wood residue, in different proportions of the constituents. Mechanical properties were evaluated by tests of traction and Charpy impact and the areas of fracture generated were evaluated by scanning electron microscopy in order to correlate aspects of fracture with the mechanical properties. It was determined the specific mass of each series of specimen of each manufactured, and the volume fraction of the composite material. The results showed that the increase in the length of the sisal fiber, tensile strength and impact of composites has been increased, reaching the composite of sisal fibre, 15 mm, the best performance with the specimen series tested. The heterogeneity of size maçaranduba residue was negative effect on the mechanical properties of composites. The hybrid composites materials sisal / wood residue with higher content of fibers elevated in 80% of the mechanical properties obtained for the composite material reinforced only by sisal fiber.
Acesso aberto (Open Access)
Comportamento mecânico e de flamabilidade de compósito de polipropileno reclicado com fibra de coco e hidróxido de alumínio
(Universidade Federal do Pará, 2006-05-02) SILVA, Vera Lúcia Dias da; DIAS, Carmen Gilda Barroso Tavares; http://lattes.cnpq.br/2113791118142177
The plastic recycling has been an interesting possibility to minimize the destiny problem of the plastic residues. The polypropylene (PP) is enters the types polymers of larger consumption, therefore the utilization of this material has been enabling the studies development of great scientific and social relevance. This polymer presents excellent cost-performance relation, besides can be easily conformed and to exibit mechanical properties that turns it useful in several applications. However, this material when being burnt generates products that act as combustible so that, for some uses, flame resistance good is necessary. This can be gotten by flame retardant addition, that has the intention to increase the resistance of this material to the ignition and, at the same time reducing the propagation speed of the flame. The aluminium hydroxide, or simply alumina hydrate, is the flame retardant agent used most in the market, therefore it also acts as smoke suppressant and it does not liberate toxic gases during the burning. However, for such properties, high alumina hydrate concentrations are necessary. This causes deterioration in the physical properties of the materials for not have reinforcing character. The natural fibres own good reinforcement capacity when combined adequately with polymers. Also presenting advantages as low cost, low density, biodegradability and in the combustion does not emanate toxic gases. In this work, mixtures contend alumina hydrate and coco fibres had been incorporated polypropylene with the objective of if finding an properties rocking adequate for use of this composite with characteristics flame resistance and mechanical performance. The composites were molded by hot compression and characterized by IV, DRX, MEV, mechanical and non-flammability tests. Increase in the elasticity modulus of the composites in general was observed, as well as increase in the tenacity resistance of the PP/coco fiber composite regarding pure PP. The results had indicated the efficiency of alumina hydrate as it flame retardant, in all the composites, except PP/F, classifying the materials as V-0 according to international norm UL 94V.
Acesso aberto (Open Access)
Compósito de argamassa de cimento reforçada por fibra de sisal com entalhe definidos: caracterização mecânica e mecanismo de falha
(Universidade Federal do Pará, 2010) PERES, Maria das Neves Pontes Barata; FUJIYAMA, Roberto Tetsuo; http://lattes.cnpq.br/3165747089941318
In this work, we developed a new composite material using as a matrix of cement mortar reinforced with sisal fibers to 1% by weight, which were manually cut into lengths of 15 mm and 25 mm used without surface treatment using the lowest possible level of technological processes in manufacturing steps. The research was conducted to study the mechanisms of failure of this new material. The composites were produced with manual molding using immersion vibrator for better densification. Specimens were fabricated of the pure base and with the composites with sisal fiber, with pre-defined slots of 1.7 mm, 3,0 mm and 5,0 mm. The mechanical properties were evaluated by a bending test at three points and correlated with the fractographic appearance made in the Scanning Electron Microscope. The results showed that the presence of sisal fibers, embedded in cement paste,plastic shrinkage caused restriction of fresh mixture, possibly due to high water absorption capacity of fibrous reinforcement, an increase in mechanical strength and increased toughness of the composite over the base between the series of notches, decreasing the tendency to sudden fracture.
Acesso aberto (Open Access)
Confecção de discos de desbaste a partir de AI2O3 e pó de vidro
(Universidade Federal do Pará, 2009) OLIVEIRA, Rosane Felice de; DIAS, Carmen Gilda Barroso Tavares; http://lattes.cnpq.br/2113791118142177
This article describes the development of abrasive and cutting disks made of alumina and waste glass powder to apply in cutting tools. These disk mills are used to micromize rigid post-consumed thermoplastics and let its use in a lot of recycling process, as rotomolding. This cutting disk uses glass powder as a fluxing agent and poly(ethylene terephthalate) post-consumed to give a plastic behavior to the powder, making it easier to fill in the mold. The amounts of glass powder were analyzed from previous studies with different minerals, as diopside and feldspar, since the studies with waste glass powder substituting natural minerals are recent. The development of the disks occurs in two steps. The first one is the homogeneization of the compounds with the calculated amounts. Afterwards it's pressed and taken to the mufla to get the percolation of the resin and its complete degradation up to a temperature of 900oC, pre-sintering and soften the silicates. After getting these green composites, it happens the second and final step, when the disks are sintered to decrease the porosity and improve its strength, followed by a superficial finish and cutting tests.
Acesso aberto (Open Access)
Correlação da coalescência de microcavidades com as propriedades mecânicas e elétricas de fios para Tx e Dx de energia elétrica da liga base Al-0,5%Cu-[0,24-0,28]%Fe modificada com teores de silício
(Universidade Federal do Pará, 2013-07) MONTEIRO, Valmor Capanema Oliveira; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290
In this study, na attempt is made to establish the influence of the concentration [0.5, 0.7 and 0.9]% Si as modifiers of alloys Al-0,05% Cu-[0.24 to 0.28]%Fe, evaluated by aspects that took into account operational parameters such as horizontal unidirectional leaks: Speeds (Vs) and Exchange Solidification (Tx). After cutting and machining cylindrical profiles were obtained with diameters of 9.5mm and length of 120mm, from which, after the cold working operations, were obtained wires with diameters of 2.7, 3.0, 3.8 and 4.0 mm. These profiles were subjected to electrical characterization on the basis of the electrical conductivity, tomechanical characterization based on assays stress/strain, emphasizing elongation [%], and structural characterization longitudinal sections, with emphasis on distribution of second phase particles, and aspect of the fracture, with emphasis on the relationship L/W length (L) and width (W) of the dimples.
Acesso aberto (Open Access)
Desenvolvimento e caracterização acústica de painéis multicamadas unifibra, multifibras e mesclados, fabricados a partir de fibras vegetais
(Universidade Federal do Pará, 2009-12-01) BASTOS, Leopoldo Pacheco; MELO, Gustavo da Silva Vieira de; http://lattes.cnpq.br/8850986817571748
In a time when high noise levels are part of people’s daily lives, the search for noise control is not only evident, but providential. Currently, noise pollution, to a worldwide level, is not more serious than air and water pollution only. In Brazil, the situation is not different because it is estimated that more than 15 million people have some kind of hearing loss degree due to this environmental problem. Acoustic devices such as panels, barriers, etc., when of high efficiency, generally, are of difficult acquisition due to high costs, turning, in many cases, their use impracticable, mainly for limited budget small-sized companies. Thus, alternative solutions, starting with new acoustic materials that are less costly and have satisfactory performance, emerge as a great option. Considering the global environmental trends, the use of vegetable fibers is a great opportunity to aggregate value, and technological development for agricultural producing countries, like Brazil. Beyond that, such fibers are easy to get, exist in abundance, are non toxic and derive from renewable sources. This work will present the methodology of development of panels made from vegetable fibers (açaí, coconut, sisal and palm) and binding agent based on acrylate and water, as well as the methodology used to characterize them acoustically on a scale model reverberant chamber, based on ISO 354/1999. These panels are made of pressed layers of fibers interspersed with layers of binding agent. The fibers are extracted, washed, dried, and treated when necessary, while the binding agent is obtained commercially. The panels sound absorption data are obtained through a four channel frequency analyzer using the noise interruption method. Comparison of results between alternative and conventional material based panels allows to the conclusion that the acoustical performance shown by some newly developed panels are very satisfactory, since their sound absorption coefficients were compatible, and in some cases, higher to those presented by conventional materials in a given frequency range. Finally, a numerical-experimental comparison is performed in order to evaluate the influence of sisal absorbing panels over the acoustics characteristics of a small classroom.
Acesso aberto (Open Access)
Determinação do calor específico de ligas AlCu produzidas em um dispositivo de solidificação unidirecional vertical ascendente
(Universidade Federal do Pará, 2008-11-24) MARTINS, Marcelo Gonçalves; SÁ, Fernando Antonio de; http://lattes.cnpq.br/8275621144223544
The knowledge of the properties of the thermophysics is extremely important to the study of the metallic alloys obtained from the solidification, once this one it is directly related to the heat transfer coefficient at the metal / mold interface. Thus, the researchers group of metallurgy and environment – GAPEMM of Federal University of Pará develops a line of research that proposes to develop techniques and procedures which has as main objective to determine them. On the other side, it is known that there is a significant correlation among process, structure, and properties obtained from a material during solidification. Since the distribution of solute in a metallic alloy occurs in a heterogeneous way. The way the solidification happens and the quantification of the varieties involved in the process has fundamental influence in the properties of the material. The present study used alloys Al-Cu (Al-2%Cu, Al-5%Cu e Al-8%Cu) obtained from a process upward directional solidification, made through one dispositive planned, constructed and calibrated by gapemm. Through these researches, there’s the intention to study the specific heat as it gets away the plate mold as well as the raise of the solute content. To do this, it was used a technique known in the literature as the Newton´s law cooling, which makes it possible through the curves of temperature x time to determine the necessary temperatures that will allow the calculation of the specific heat.
Acesso aberto (Open Access)
Efeito de adições de Ni e Mg sobre o comportamento térmico, mecânico e elétrico de ligas Al-Cu-Fe solidificadas unidirecionalmente
(Universidade Federal do Pará, 2013) SOUZA, Pedro Henrique Lamarão; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290
This work studied the influence of Mg and Ni solute content on the modification of the thermal, electrical and mechanical properties of an Al-Cu-Fe alloy for application as an electrical conductor. To realize the present study, the alloys were obtained by unidirectional horizontal casting, starting from the commercial pure aluminum with the addition of 0.05wt% Cu and [0.24 to 0.28]wt% Fe content. This basis was modified on a first stage with 0.45, 0.60 and 0.80wt% of Mg content. The alloys obtained with these contents had its properties studied for the selection of a Mg content for further Ni addition at the alloy. The study of these properties on the first stage passed through the analysis of the thermal properties: growth rate (VL) and cooling rate (Ṫ). The electrical characterization studied the electrical conductivity property (φ) and the following mechanical properties were determined: ultimate tensile strength (σ) and Vickers microhardness (HV). The alloy which has Ni additions passed through ageing heat treatments of 1, 4 and 8 hours. These samples were analyzed in a scanning electron microscope – SEM by the electrons backscattered – EBS and energy dispersive spectroscopy – EDS signals. As a result of the research, it was found that Mg additions had significantly influenced the alloys viscosity, increasing its growth rates at the final moments of the solidification. The microhardness tests for the aged samples showed that they suffered a significant gain of hardness at the fourth hour of ageing, also, the EDS analysis showed that Ni content increased at the same treating conditions.
Acesso aberto (Open Access)
Efeito de teores de Zr sobre as propriedades mecânicas e elétricas de ligas Al-Ec-Si aplicadas na elaboração de ligas para Tx e Dx de energia elétrica
(Universidade Federal do Pará, 2010) SANTOS, Washington Luis Reis; QUARESMA, José Maria do Vale; http://lattes.cnpq.br/7443111804471290
This paper aims to develop an analysis of the influence of Zr in the modification of important characteristics of Al-EC-Si alloys used in electrical conductors, aiming to obtain heat resistant properties. For this study, the alloys were obtained by direct casting in a U-shaped ingot mold, from the Al-EC, with a base Si content of 0,7%, and then varying with different amounts of Zr. Intending o precipitate second phase particles called dispersoid, whose main characteristic is the retention of the deformed microstructure when exposed to high temperatures, it was necessary to submit the alloys to a heat treatment of 310 ºC for 24 hours in order to cause the appearance of fine dispersoids of Al3Zr. Two steps were established to obtain the results: The Step I was composed of solidification, machining and deformation obtained with the alloys, generating the wires used in all tests. The Step II repeats the same processes adopted in the Step I, however a heat treatment of 310 ºC for 24 hours was made before deformation. The heat resistance characterization of the specimens of each alloy followed the requirements of COPEL (Companhia Paranaense de Energia Elétrica ) when submitted to temperatures of 230 ºC for 24 hours, and heat treatments at temperatures of 310 ºC and 390 ºC were also made to evaluate the thermal stability of the alloys. In general, it was observed that crescent contents of Zr results in a grain refinement and a increase of the Ultimate Tensile Strength and thermal stability of the alloy, both in the Step I and Step II. It was also observed that in Step I, the electrical conductivity was severely affected by the Zr contents and the addition of heat treatment in Step II increased the electrical conductivity of the alloy, particularly to diameters that suffered higher deformation.
Acesso aberto (Open Access)
Estudo da técnica de enchimento de chanfro do aço naval pelo processo GMAW-CW
(Universidade Federal do Pará, 2011) BARBOZA FILHO, Lúcio da Silva; BRAGA, Eduardo de Magalhães; http://lattes.cnpq.br/4783553888547500
In this work studied the operational viability and the characteristics economic and geometric of technique of the process welding GMAW -CW (additional alimentation of a cold wire) in comparison Gas Metal Arc Welding (GMAW). The alimentation system of cold wire was designed and adapted to welding gun GMAW. Used an electronic source of multiple processes adjusted in constant voltage and DC+, the gas shield was a mixture 75% Ar+25% CO2 and commercially pure CO2. The wire used was Class ER70S-6 with diameter of 1.2 mm for the electrode wire and 1.0 mm for the cold wire, the both wires were fed in heads independent. The input operating variables were the feed speed of wire energized at three levels, 4, 6 and 8 m / min and the wire feed speed in cold 50%, 60% and 70% of the wire feed speed energized . The welds were automated in simple deposited in the pushing direction and the positioning of the cold wire in a single level, Tandem in chamfer "U" steel plate ASTM 1020. The variables of response used were: superficial inspection of the cords, analysis of the geometry (width, penetration, reinforcement and dilution) and economic solder (melting rate, deposition rate, yield and operating cost). The results indicated that for surface analysis, using the AR25% CO2 gas to the surface of the strands were more homogeneous with respect to CO2 and less splash index for the analysis of economic characteristics, the process always GMAW-CW was superior to the conventional process, the operating costs the conventional process was lower, but without filling of the chamfer, which occurred with the use of GMAW-CW.
Acesso aberto (Open Access)
Estudo da viabilidade operacional do processo de soldagem MAG com alimentação adicional de arame frio
(Universidade Federal do Pará, 2007-11-09) SÁBIO, Alberto Dias; BRAGA, Eduardo de Magalhães; http://lattes.cnpq.br/4783553888547500
The present study shows experimental research of the weld concerning operational, economic and geometric viability as well as its superficial quality when using MAGCW (Metal Active Gas – Cold Wire), understood as: MAG welding process with nonenergized wire or cold wire. For the development of this research, welding MAG and MAG-CW processes have been used together with 1,2 mm of diameter consumable solid wires, class AWS E-70S6 and carbon dioxide pure, CO2, as protection gas with 17 l/min release for both processes. Automated welding was performed with electronic source adjusted in CC+, in constant tension mode, interfaced by a microcomputer. In both processes the welds were put on steel carbon samples SAE 1020, 76x155x12,7 mm size, with simple disposition passes, pulling and pushing the voltage arc. The MAG-CW process added cold wire on the electric arc region, fed by the Tandem and Twin sequential wire shape auxiliary system on plane position. The variables of influence were: Velocidade de Alimentação do Arame-Eletrodo, VAE, which varied in three levels: 6; 7,5 and 9 m/min, respectively, Velocidade de Alimentação do Arame-Fio, VAF, which also varied in three levels: 3; 4 and 5 m/min combined with VAE. Response variables for experimental evaluation were electric arc stability, economic features, geometric features and weld superficial quality. The results demonstrated satisfactory arc stability as well as high production concerning MAG process and also good superficial aspect of welds. Rising rates obtained by MAG-CW process demonstrates the superiority due to non-energized wire addition to the arc. Thus, the MAG-CW process, in comparison with MAG process, demonstrated superiority concerning the 57% in rate of fusion (RF) for the VAE of 6 m/min, 59 % for the VAE of 7,5 m/min and 53 % for the VAE in 9 m/min. it has also been observed that the same occurred with the rate of deposition (RD) increasing in all speed levels: 62% for the VAE in both conditions of 6 m/min and 7,5 m/min and in 57 % for the VAE in 9 m/min. The good performance in the increase of the taxes obtained by the process MAG-CW demonstrates advantage, with larger evidence in the acting of these characteristics, in function of the addition of cold wire to the arch.
Acesso aberto (Open Access)
Estudo de reaproveitamento de filmes de polietileno para fabricação de colchões de ar comprimido para utilização em embalagens de produtos eletroeletrônicos
(Universidade Federal do Pará, 2011-02-28) OLIVEIRA, Macêdo Santos de; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
Films of polyethylene (PE) are commonly used in packaging of small products such as packaging for digital cameras, camcorders, wine bottles, medical instruments, etc... as a function of important properties such as mechanical strength (vibration, drop, etc..) thermal (temperature, humidity, pressure) with the ease of processing and a cost. In electronics packaging, are used PE films of low density, depending on the product being package. In this work, films were evaluated as lowdensity polyethylene used for packing display panels on the production line, consisting of a single polymer, replacing the packaging of expanded polystyrene (EPS) by a polyethylene cushion with air mattress inflated with changes in the thickness of the films were subjected to the fusion of two layers of training for air mattresses, under certain conditions of temperature and pressure, where expansion of the films resulted in significant changes in physical, mechanical. The films were characterized before and after welding for clothing of air mattresses in the format of columns of air that can be molded into packaging for consumer electronics. It was observed that change according to the type of material making up the films of polyethylene, that is, the more resistant to compression test, the greater the degree of impact absorption when this raw material in the form of inflated air mattress this means an excellent performance to bear the weight of a product during the mechanical test, such as drop test, vibration test, test temperature and humidity. Studies show that we can study and test films with high strength and are discarded and reprocessed in the factories for the manufacture of inflatable cushions to be used in various products. The reuse of these raw materials helps to reduce the rate of waste disposed in the environment.
Acesso aberto (Open Access)
Fabricação e caracterização de material compósito de resina poliéster reforçada por tecido de fibra de tururi extraído da palmeira de ubuçu (Manicaria saccifera)
(Universidade Federal do Pará, 2011-04-20) DUARTE, Cláudio; FUJIYAMA, Roberto Tetsuo; http://lattes.cnpq.br/3165747089941318
The proposition of this work is to present and characterize a composite material produced with a polymeric matrix reinforced with natural fibers. The matrix is an insaturated teraftalic polyester pre -accelerated with the commercial name of Denverpoly 754 and the peroxide of MEK (Butanox M-50 ) as a catalyst in a proportion of 0,33% in volume. The natural fiber used was the “tururi”, obtained in the Marajó region, in the municipalite of Muaná. This fiber was submitted to two types of aperture in the transversal axis, in a proportion of 50% and 100% of the original width. The fabrication method of the composite was made through a manual lamination process (hand lay up) using a controlled pression by weights previously quantified. Phisycal, mechanical and microscopic characteristics were obtained for the fiber and the composite material , and in this way , the traction resistence, specific mass, weight of the fabric , mass fraction and microscopic image before and after the traction tests for the fiber fabric were made, and tests of traction for the composite material. The fabric of tururi, has shown a traction resistence of 29,95 MPa (without aperture), 12,27 MPa (aperture of 50%) and 9,38 MPa (aperture of 100% ). The aperture produces a reduction of the traction the resistence of the tururi fabric, and consequently reducing the traction resistence of the material. The weight of the fabric was reduced with the aperture. The mass fraction of the fabric of the composite was 14,39%(without aperture), 9,35 % (aperture of 50%) and 7,19% (aperture f 100%). The traction resistance was of 35,76 MPA (withot perture), 19,01 (50% aperture) and 16,8 MPa (100% aperture). The mechanical resistence has shown values much like those encountered in the literature for composites reinforced with natural fibers. The images obtained with swapping electronic microscopie, validated the mechanical properties obtained for each situation of the material and fibers.