Aplicação de ferramentas cerâmicas à base de óxido de alumínio no torneamento da superliga VAT 32®.
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Data
2020-02-12
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Universidade Estadual Paulista (Unesp)
Resumo
A superliga de ferro-níquel VAT 32® foi desenvolvida como um substituto da liga de níquel 751 (UNS N07751) usada na fabricação de válvulas automotivas para motores de combustão interna de alto desempenho. A formação de carbonetos de nióbio confere a esta liga elevada resistência ao desgaste, desejada na aplicação em válvulas automotivas, criando-se, porém, uma maior dificuldade na usinagem deste material. Este trabalho estudou o torneamento da liga VAT 32® com dois tipos de ferramentas cerâmicas, sendo pastilhas de materiais cerâmicos experimentais, a primeira de Al2O3 + MgO e a segunda de Al2O3 + Cr2O3. Por meio do método de Taguchi de planejamento experimental, foram obtidas as combinações e os efeitos principais dos parâmetros de entrada: velocidade de corte, avanço, profundidade de corte para avaliar cada uma das variáveis respostas, sendo elas potência de usinagem, desgaste das ferramentas, qualidade superficial das peças usinadas, e os sinais de emissão acústica e vibração do processo. Foi obtida também, através da análise da razão sinal ruído (S/N) de Taguchi, a composição dos parâmetros de corte em que o processo apresentou menor variabilidade das características de qualidade, o chamado processo robusto. Os tipos de desgaste e tipos de cavaco também foram observados, e foi evidenciado que a pastilha contendo óxido de cromo teve um resultado melhor que a pastilha com óxido de magnésio, sendo superior nos parâmetros de desgaste de flanco (Vb), rugosidade (Ra), apresentando valores de consumo de Potência e Emissão Acústica menores. Apenas a Vibração apresentou valores aproximados entre as duas pastilhas quando observado as respostas obtidas nos ensaios realizados.
The VAT 32®Iron-Nickel Superalloy was developed as a replacement for 751Nickel Alloy (UNS N07751) in the manufacture of automotive valves for high performance internal combustion engines. The formation of niobium carbides gives this alloy high wear resistance, which is desired for application in automotive valves, but creates greater difficulty in machining this material. This work studied the turning of VAT 32® alloy with two types of ceramic tools. Being inserts of experimental ceramic materials, the first of Al2O3 + MgO and the second of Al2O3 + Cr2O3. Using Taguchi's experimental design method, combinations and main effects of the input parameters were obtained: cutting speed, feed rate, depth of cut to evaluate each of the response variables, such as machining power, tool wear, surface quality of the machined parts, and the acoustic emission and process vibration signals. Through the analysis of Taguchi's signal-to-noise ratio (S/N) were also obtained the composition of the cutting parameters in which the process presented less variability of the quality characteristics, the so-called robust process. Wear and chip types were also observed, and it was evidenced that the chromium-containing tablet had a better result than the magnesium oxide tablet. Being superior in the flank wear (Vb), roughness (Ra) parameters, presenting lower Power and Acoustic Emission consumption values. Only the vibration presented approximate values when analyzing the responses obtained in the performed tests.
The VAT 32®Iron-Nickel Superalloy was developed as a replacement for 751Nickel Alloy (UNS N07751) in the manufacture of automotive valves for high performance internal combustion engines. The formation of niobium carbides gives this alloy high wear resistance, which is desired for application in automotive valves, but creates greater difficulty in machining this material. This work studied the turning of VAT 32® alloy with two types of ceramic tools. Being inserts of experimental ceramic materials, the first of Al2O3 + MgO and the second of Al2O3 + Cr2O3. Using Taguchi's experimental design method, combinations and main effects of the input parameters were obtained: cutting speed, feed rate, depth of cut to evaluate each of the response variables, such as machining power, tool wear, surface quality of the machined parts, and the acoustic emission and process vibration signals. Through the analysis of Taguchi's signal-to-noise ratio (S/N) were also obtained the composition of the cutting parameters in which the process presented less variability of the quality characteristics, the so-called robust process. Wear and chip types were also observed, and it was evidenced that the chromium-containing tablet had a better result than the magnesium oxide tablet. Being superior in the flank wear (Vb), roughness (Ra) parameters, presenting lower Power and Acoustic Emission consumption values. Only the vibration presented approximate values when analyzing the responses obtained in the performed tests.
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Palavras-chave
Usinagem, Rugosidade, Desgaste, Monitoramento, Método Taguchi, Machining, Roughness, Tool wear, Monitoring, Taguchi method, Taguchi, Métodos (Controle de Qualidade), Aspereza de superfície, Material cerâmico