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Search Results: 1 - 10 of 199305 matches for " Paulo Roberto de;Catai "
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Studies on the cooling minimum quantity and conventional cooling at hardened steels in grinding process
Aguiar, Paulo Roberto de;Catai, Rodrigo Eduardo;Bianchi, Eduardo Carlos;Freitas, Roberto de;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2007, DOI: 10.1590/S1678-58782007000200002
Abstract: the purpose of this work is to explain the concept of cutting fluids reasonable usage through the fluid minimum quantity in grinding processes. on that purpose, the development of a new nozzle and an own and adequate methodology should be required in order to obtain good results and compare them to the conventional methods. the analysis of the grinding wheel/cutting fluid performance was accomplished from the following input parameters: flow rate variation by nozzle diameter changes (three diameters values: 3mm, 4mm and 5mm), besides the conventional round nozzle already within the machine. integral oil and a synthetic emulsion were used as cutting fluids and a conventional grinding wheel was employed. the workpieces were made of steel vc 131, tempered and quenched with 60hrc. thus, as the flow rate and the nozzle diameter changes, keeping steady fluid jet velocity (equal to cutting velocity), attempted to find the best machining conditions, with the purpose to obtain a decrease on the cutting fluid volume, taking into consideration the analysis of the process output variables such as cutting strength, cutting specific energy, grinding wheel wear and surface roughness. it was verified that the 3mm diameter optimized nozzle and the integral oil, in general, was the best combination among all proposed.
Analysis of the influence of infeed rate and cutting fluid on cylindrical grinding processes using a conventional wheel
Bianchi, Eduardo Carlos;Franzo, Carolina Grimm;Aguiar, Paulo Roberto de;Catai, Rodrigo Eduardo;
Materials Research , 2004, DOI: 10.1590/S1516-14392004000300004
Abstract: new worldwide trends such as globalization have rendered grinding processes increasingly important for industry, making it essential to perform in-depth studies of variations in grinding process parameters in the pursuit of greater cost effectiveness. this paper presents a comparative analysis of three different infeed rates, using a conventional grinding wheel on quenched and tempered d2 steel workpieces. higher infeed rates are known to be correlated with shorter grinding times, rendering the process more economically attractive. two different coolant fluids, 5% emulsion and pure oil, were used. the tests were carried out using the smallest possible amount of coolant and an optimized 5 mm diameter nozzle. the parameters analyzed were tangential force, specific energy, acoustic emission, roundness error and surface roughness. the surfaces of the workpieces were also examined by scanning electron microscopy (sem). the results revealed that increased infeed rates could reduce processing times without compromising the quality of the workpiece profile, thereby reducing the cost of the process. the best cutting fluid, albeit more harmful to human health and less environmentally friendly, was found to be pure oil.
Influência na qualidade final de metais retificados através da varia??o da velocidade de mergulho
Alves, Manoel Cleber Sampaio;Bianchi, Eduardo Carlos;Aguiar, Paulo Roberto de;Catai, Rodrigo Eduardo;
Rem: Revista Escola de Minas , 2009, DOI: 10.1590/S0370-44672009000100010
Abstract: grinding, the final stage of the machining process, employs a significant amount of cutting fluids for lubrication, cooling and swarf removal. however, these cutting fluids are extremely aggressive to the environment. with technological progress, the world tendency is to produce more and more sophisticated pieces,having a high degree of geometrical and dimensional tolerance, good surface finish, hlow cost and, mainly, insignificant impact on the environment. therefore, recycling cutting fluids is intrinsic and cost-cutting for the grinding process and this work aimed to assess several output parameters in external cylindrical grinding: tangential force, acoustic emission, surface roughness, roundness, tool wear, and residual stress. also, analysis of microstructural features through scanning electron microscopy (sem) was carried out. tests was developed for abnt d6 steel, using a cbn grinding wheel with vitrified bond and two types of cutting fluids analyzing cutting fluid performance, grinding wheel time and feed rate, the best grinding conditions were found, leading to a decrease in cutting fluid volume and grinding time without impairing the geometrical and dimensional parameters, surface finish and surface integrity of the parts.
Evaluation of the thermal damages in inlet engine valves varying the grinding wheels and the cutting fluids
Bianchi, Eduardo Carlos;Silva, Eraldo Janonne da;Aguiar, Paulo Roberto de;Catai, Rodrigo Eduardo;
Rem: Revista Escola de Minas , 2003, DOI: 10.1590/S0370-44672003000200003
Abstract: this paper presents an experimental research in which the thermal damage in inlet engine valves grinding was evaluated. four different cutting fluids and two grinding wheel were tested and were analyzed the workpiece residual stress, the micro hardness and the optical observation of the workpiece microstructure. the cutting fluid and the grinding wheel types adopted resulted in different types of residual stress. the cutting oil resulted in compressive residual stresses, even using the conventional wheel. the cbn wheel, due to the best proprieties of its grains resulted in compressive residual stresses for all fluids tested by the reducing of the grinding energy and its easier dissipation from the grinding zone. the microstructure investigations showed that the source of the tensile residual stresses observed was the thermal cycles imposed. no microstructure alterations were detected. although, the absence of microstructure alterations not always suggests that favorable residual stresses can be obtained.
Analysis of the influence of infeed rate and cutting fluid on cylindrical grinding processes using a conventional wheel
Bianchi Eduardo Carlos,Franzo Carolina Grimm,Aguiar Paulo Roberto de,Catai Rodrigo Eduardo
Materials Research , 2004,
Abstract: New worldwide trends such as globalization have rendered grinding processes increasingly important for industry, making it essential to perform in-depth studies of variations in grinding process parameters in the pursuit of greater cost effectiveness. This paper presents a comparative analysis of three different infeed rates, using a conventional grinding wheel on quenched and tempered D2 steel workpieces. Higher infeed rates are known to be correlated with shorter grinding times, rendering the process more economically attractive. Two different coolant fluids, 5% emulsion and pure oil, were used. The tests were carried out using the smallest possible amount of coolant and an optimized 5 mm diameter nozzle. The parameters analyzed were tangential force, specific energy, acoustic emission, roundness error and surface roughness. The surfaces of the workpieces were also examined by scanning electron microscopy (SEM). The results revealed that increased infeed rates could reduce processing times without compromising the quality of the workpiece profile, thereby reducing the cost of the process. The best cutting fluid, albeit more harmful to human health and less environmentally friendly, was found to be pure oil.
Evaluation of the thermal damages in inlet engine valves varying the grinding wheels and the cutting fluids
Bianchi Eduardo Carlos,Silva Eraldo Janonne da,Aguiar Paulo Roberto de,Catai Rodrigo Eduardo
Rem: Revista Escola de Minas , 2003,
Abstract: This paper presents an experimental research in which the thermal damage in inlet engine valves grinding was evaluated. Four different cutting fluids and two grinding wheel were tested and were analyzed the workpiece residual stress, the micro hardness and the optical observation of the workpiece microstructure. The cutting fluid and the grinding wheel types adopted resulted in different types of residual stress. The cutting oil resulted in compressive residual stresses, even using the conventional wheel. The CBN wheel, due to the best proprieties of its grains resulted in compressive residual stresses for all fluids tested by the reducing of the grinding energy and its easier dissipation from the grinding zone. The microstructure investigations showed that the source of the tensile residual stresses observed was the thermal cycles imposed. No microstructure alterations were detected. Although, the absence of microstructure alterations not always suggests that favorable residual stresses can be obtained.
Performance of aerodynamic baffles in cylindrical grinding analyzed on the basis of air layer pressure and speed
Catai, Rodrigo Eduardo;Silva, Leonardo Roberto da;Bianchi, Eduardo Carlos;Aguiar, Paulo Roberto de;Zílio, Felipe M.;Valarelli, Ivan De Domenico;Salgado, Manoel Henrique;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2008, DOI: 10.1590/S1678-58782008000100007
Abstract: over the years, grinding has been considered one of the most important manufacturing processes. grinding is a high precision process, and the loss of a single workpiece in this stage of the production is unacceptable, for the value added to the material is very high due to many processes it has already undergone prior to grinding. this study aims to contribute toward the development of an experimental methodology whereby the pressure and speed of the air layer produced by the high rotation of the grinding wheel is evaluated with and without baffles, i.e., in an optimized grinding operation and in a traditional one. tests were also carried out with steel samples to check the difference in grinding wheel wear with and without the use of baffles.
Desenvolvimento de um torquímetro de precis?o para o estudo do desempenho de implantes osseointegrados
Bianchi, Eduardo Carlos;Aguiar, Paulo Roberto de;Santos, Marcelo de Almeida Souza;Gon?alves, Jo?o Roberto;Barbosa, Darceny Zanetta;Catai, Rodrigo Eduardo;
Rem: Revista Escola de Minas , 2003, DOI: 10.1590/S0370-44672003000200008
Abstract: this paper has as objective, to present the project, the construction and the results obtained in the study of the osseointegration with a torque gauge of high precision. the torque gage, especially developed for this research type, was used to improvement of odontological research on osseointegration of dental implant. the implants were done in seven rabbits that were available after 21 and 42 days. in some rabbits were made ultra-sonic stimulations at rabbits' implants. the results showed that the torque to remove the implant of the rabbits is directly proportional at the time of osseointegration and that the ultra-sonic stimulations can also influence the torque in some cases.
Analysis of the cutting fluid influence on the deep grinding process with a CBN grinding wheel
Fusse, Ronaldo Yoshinobu;Fran?a, Thiago Valle;Catai, Rodrigo Eduardo;Silva, Leonardo Roberto da;Aguiar, Paulo Roberto de;Bianchi, Eduardo Carlos;
Materials Research , 2004, DOI: 10.1590/S1516-14392004000300013
Abstract: the application of cutting fluid in a deep grinding process is becoming more and more important, mainly where the cutting fluids are used as an "external" agent to the grinding conditions. the role of the fluid in grinding operations is in refrigeration of the workpiece, removal of the shavings, lubrication of the grinding zone, and refrigeration and cleaning of the wheel. the efficiency of a cutting fluid will depend mainly of the type of fluid that will be used. in this work, the influences of the type of cutting fluid used in a deep grinding process of the steel vc131 using cbn grinding wheel are analyzed. three different types of cutting fluids were used: a vegetable emulsion, a synthetic solution and a integral oil. the variables analyzed during and after the grinding process were the grinding force, the superficial roughness, the acoustic emission (ea), the temperature of the piece and the g ratio (relationship between the volume of material removed from the piece and the volume worn off the grinding wheel). the integral oil showed the best performance relative to the following output variables: ea, cutting force and g ratio. the vegetal emulsion was the fluid that best dissipated heat from the cutting region.
Para além do Rio Grande: os impactos da economia paulista sobre O Triangulo Mineiro
Oliveira, Paulo Roberto de;
História (S?o Paulo) , 2008, DOI: 10.1590/S0101-90742008000200010
Abstract: in this work our intention was to investigate the impact of sao paulo's coffee economy on the minas gerais triangle region, during its penetration into the area because of the extension of the mogiana railroad company in 1889. we attempt to understand the impact caused along this coffee railroad in a region where this product almost did not exist, and the changes that occurred to the economic panorama of the region. furthermore we have taken as an example, the city of uberaba, the most important, in this region at that time.
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