Influência da lubrirrefrigeração na qualidade superficial de metais retificados
Carregando...
Data
2011-12-01
Autores
Alves, Manoel Cléber de Sampaio [UNESP]
Bianchi, Eduardo Carlos [UNESP]
Aguiar, Paulo Roberto de [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Escola de Minas
Resumo
Na fabricação de componentes mecânicos precisos, que necessitam de alta resistência mecânica e ao desgaste, utiliza-se o processo de retificação, para conferir o acabamento final desejado e, também, para eliminar as deformações ocorridas durante a têmpera do aço. No entanto, as condições de retificação devem ser adequadas, para que não sejam introduzidas falhas na peça. Novos conceitos de lubrificação e refrigeração, para o processo de retificação, estão sendo pesquisados, de forma a diminuir os custos e os danos ambientais causados pelos fluidos de corte. Nesse trabalho, é analisada a influência das técnicas de mínima quantidade de lubrificante (MQL), refrigeração otimizada e refrigeração convencional, com diferentes vazões e velocidade de aplicação do fluido de corte, na qualidade das peças produzidas com aço ABNT 4340 endurecido, no processo de retificação cilíndrica externa de mergulho com a utilização de rebolos de CBN. O Aço ABNT 4340 apresenta várias aplicações industriais, sendo considerado de uso aeronáutico devido, sua alta resistência mecânica sem aumentar o peso dos componentes que o utilizam. A análise da qualidade das peças foi realizada com a verficação das rugosidades e com a análise de microscopias eletrônicas de varredura. Verificou-se, ainda, a força tangencial de corte. em relação às diferentes formas de aplicação do fluido de corte, notou-se o melhor desempenho da aplicação otimizada, para maiores velocidades, mostrando a eficiência do bocal utilizado. O processo otimizado e o processo MQL foram capazes de manter a integridade superficial das peças produzidas. Exceção somente para a condição MQL com vazão de fluido de corte de 40ml/h, que produziu trincas e queima superficial. Rebolos com baixa concentração de CBN, conseqüentemente mais baratos, proporcionaram bons resultados, quando associados com técnicas mais eficientes de aplicação de fluido de corte apresentando desgaste reduzido.
In the manufacture of precise mechanical components, which requires high mechanical and wear resistance, the grinding process is used to give the desired finishing and to eliminate the distortion occurred during the quenching step in the steel heat treatment process. However, the grinding conditions should be appropriate so that flaws are not incorporated into the piece. New lubrication and cooling concepts for the grinding process are being researched in order to reduce costs and environmental damage caused by cutting fluids. The influences on the surface integrity and surface quality of the ABNT 4340 hardened parts have been analyzed in this research by employing the minimum quantity of lubrication (MQL), optimized and conventional cooling, different flows and velocities in the application of the cutting fluid and a super abrasive grinding wheel in the cylindrical plunge grinding process. The ABNT 4340 steel, with several industrial applications, is considered for aeronautical use due to its high strength without increasing the weight of the components. The quality analysis of the parts was done by roughness verification and electron scanning microscopy (ESM). The tangential cutting force was also verified. Regarding the different forms of the cutting fluid application, the best performance was verified for the optimized for higher speeds showing the efficiency of the nozzle used. The optimized and the MQL processes were able to maintain the surface hardness and integrity of the produced parts. The only exception occurred for the MQL condition with a cutting fluid flow rate at 40ml/h, which led to cracks and superficial burns. Grinding wheels with low CBN concentration, therefore cheaper, produced good results when associated with more efficient techniques of cutting fluid application, showing reduced wear.
In the manufacture of precise mechanical components, which requires high mechanical and wear resistance, the grinding process is used to give the desired finishing and to eliminate the distortion occurred during the quenching step in the steel heat treatment process. However, the grinding conditions should be appropriate so that flaws are not incorporated into the piece. New lubrication and cooling concepts for the grinding process are being researched in order to reduce costs and environmental damage caused by cutting fluids. The influences on the surface integrity and surface quality of the ABNT 4340 hardened parts have been analyzed in this research by employing the minimum quantity of lubrication (MQL), optimized and conventional cooling, different flows and velocities in the application of the cutting fluid and a super abrasive grinding wheel in the cylindrical plunge grinding process. The ABNT 4340 steel, with several industrial applications, is considered for aeronautical use due to its high strength without increasing the weight of the components. The quality analysis of the parts was done by roughness verification and electron scanning microscopy (ESM). The tangential cutting force was also verified. Regarding the different forms of the cutting fluid application, the best performance was verified for the optimized for higher speeds showing the efficiency of the nozzle used. The optimized and the MQL processes were able to maintain the surface hardness and integrity of the produced parts. The only exception occurred for the MQL condition with a cutting fluid flow rate at 40ml/h, which led to cracks and superficial burns. Grinding wheels with low CBN concentration, therefore cheaper, produced good results when associated with more efficient techniques of cutting fluid application, showing reduced wear.
Descrição
Palavras-chave
Retificação, CBN, Aço ABNT 4340, mínima quantidade de lubrificante (MQL), lubrificação convencional, lubrificação otimizada, Grinding process, CBN grinding wheel, ABNT 4340 Steel, minimum quantity of lubrication (MQL), optimized cooling, conventional cooling
Como citar
Rem: Revista Escola de Minas. Escola de Minas, v. 64, n. 4, p. 505-512, 2011.