Desempenho da friabilidade de grãos de CBN na retificação do ferro fundido nodular perlítico FE 70002
Carregando...
Arquivos
Data
2019-03-01
Autores
Lopes, José Claudio
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
A aplicação de ferro fundido nodular perlítico na indústria vem se destacando devido a sua elevada resistência mecânica e possibilidade de fácil manufatura, uma vez que sua alta fluidez permite fundir peças com dimensões próximas à final. Entretanto, em componentes que exigem elevada precisão dimensional, como eixos virabrequins, pistões e bielas, por exemplo, é indispensável a utilização do processo de retificação. A indústria desenvolveu diversos tipos de grãos abrasivos de óxido de alumínio para essa aplicação. Todavia, o desenvolvimento de novos grãos abrasivos visa readequar o seguimento, de modo a aplicar no mercado uma nova classe de grãos abrasivos de nitreto de boro cúbico (CBN), suprindo uma lacuna existente no desenvolvimento industrial. Desta forma, foram desenvolvidos diversos tipos de grãos abrasivos de CBN com diferentes níveis de friabilidade, visando assim um melhor desempenho de acordo com determinado processo. Embora a retificação de ferro fundido nodular perlítico seja ampla na indústria, são escassos os estudos pertinentes ao assunto, sendo exíguo sua aplicação quando relacionado a friabilidade de grãos abrasivos. Portanto, vislumbrou-se o estudo do tema a partir da iniciativa da indústria, fabricante de rebolos de CBN, para o entendimento dos fenômenos relacionados ao processo, catalogando o funcionamento dos rebolos e estabelecendo relações em prol do seu desempenho durante o processo de retificação. Deste modo, a rugosidade média aritmética, desvios de circularidade, desgaste diametral do rebolo, relação G, consumo de potência elétrica, sinal de emissão acústica, microscopia óptica da superfície retificada da peça e microdureza foram as variáveis estudadas para avaliação dos rebolos. Logo, os rebolos com grãos abrasivos menos friáveis se comportaram de maneira mais eficiente na maioria dos resultados analisados, com exceção do consumo de potência elétrica, onde os grãos abrasivos mais friáveis se comportaram de melhor forma, sendo estimado que seu desempenho tornar-se-ia pior somente a partir da velocidade de avanço de 1,7 mm/min, o que pode ser mensurado devido a linearização do consumo de potência elétrica durante o processo de retificação.
The application of pearlitic ductile cast iron in the industrial sector has been outstanding due to its high mechanical resistance and possibility of easy manufacture, since its high fluidity allows melting pieces with dimensions close to the end. However, for components requiring high dimensional precision, such as crankshafts, pistons and connecting rods, for example, it is essential to use the grinding process. The industry has developed various types of aluminum oxide abrasive grains for this application. Thereby, the development of new abrasive grains aims at re-adjusting the follow-up, so that a new class of cubic boron nitride (CBN) abrasive grains is available on the market, supplying a gap in industrial development. Thus, different types of CBN abrasive grains with different levels of friability were developed, aiming at a better performance according to a certain process. Although the grinding of pearlitic ductile cast iron is ample in the industry, the pertinent studies are rare, and its application is scarce when related to the friability of abrasive grains. Therefore, the study of the theme was glimpsed from the initiative of the industry, manufacturer of CBN grinding wheels, to understand the phenomena related to the process, cataloging the grinding of the grinding wheels and establishing relationships in favor of its performance during the grinding process. In this way, the average surface roughness, roundness deviation, diametrical wear wheel, G-ratio, electric power consumption, acoustic emission, optical microscopy of the ground workpiece surface and microhardness were the variables studied for the evaluation of the grinding wheels. Therefore, grinding wheels with less friable abrasive behaved more efficiently in most of the analyzed results, with the exception of electric power consumption, where the most friable abrasive grains behaved in a better way, was worse only from the feed rate of 1.7 mm/min, which can be measured due to the linearization of the electric power consumption during the grinding process.
The application of pearlitic ductile cast iron in the industrial sector has been outstanding due to its high mechanical resistance and possibility of easy manufacture, since its high fluidity allows melting pieces with dimensions close to the end. However, for components requiring high dimensional precision, such as crankshafts, pistons and connecting rods, for example, it is essential to use the grinding process. The industry has developed various types of aluminum oxide abrasive grains for this application. Thereby, the development of new abrasive grains aims at re-adjusting the follow-up, so that a new class of cubic boron nitride (CBN) abrasive grains is available on the market, supplying a gap in industrial development. Thus, different types of CBN abrasive grains with different levels of friability were developed, aiming at a better performance according to a certain process. Although the grinding of pearlitic ductile cast iron is ample in the industry, the pertinent studies are rare, and its application is scarce when related to the friability of abrasive grains. Therefore, the study of the theme was glimpsed from the initiative of the industry, manufacturer of CBN grinding wheels, to understand the phenomena related to the process, cataloging the grinding of the grinding wheels and establishing relationships in favor of its performance during the grinding process. In this way, the average surface roughness, roundness deviation, diametrical wear wheel, G-ratio, electric power consumption, acoustic emission, optical microscopy of the ground workpiece surface and microhardness were the variables studied for the evaluation of the grinding wheels. Therefore, grinding wheels with less friable abrasive behaved more efficiently in most of the analyzed results, with the exception of electric power consumption, where the most friable abrasive grains behaved in a better way, was worse only from the feed rate of 1.7 mm/min, which can be measured due to the linearization of the electric power consumption during the grinding process.
Descrição
Palavras-chave
Retificação, Friabilidade, Nitreto de boro cúbico (CBN), Ferro fundido nodular perlítico, Grinding process, Friability, Cubic boron nitride (CBN), Pearlitic ductile cast iron