Estudo do desgaste das ferramentas no microfresamento frontal
Carregando...
Data
2018-09-03
Autores
Manarelli, Flávio Henrique
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
A microusinagem é um dos processos de fabricação capaz de produzir produtos ou geometrias de precisão e complexidade com detalhes menores que 1 mm. Contudo, para um melhor desempenho do processo de usinagem associado à qualidade do produto, entender a interação peça-ferramenta é fundamental. Esta pesquisa determinou a influência do tipo de corte e do avanço da ferramenta no desgaste da fresa (ferramenta), na energia específica de corte (processo) e na rugosidade (peça), ao empregar a operação de microfresamento de topo no aço COS AR60 de grãos ultrafinos. Os ensaios foram realizados em um centro de usinagem Romi D600 com a adaptação de um cabeçote de alta rotação (60 krpm) sem aplicação de fluido de corte. Microfresas de topo reto (Ø 800 µm) com substrato de metal duro e revestidas com TiAlN foram aplicadas nos testes. A profundidade de usinagem e a velocidade de corte foram mantidas constantes em 160 µm e 60 m/min, respectivamente. Foram variados o avanço por dente (3 e 10 µm/z) e o tipo de corte (simétrico em cheio e em face e assimétrico concordante e discordante). Análise de Variância (ANOVA) com intervalo de confiança de 95% foi aplicada a cada uma das três réplicas. Os resultados indicaram que os níveis de desgaste e a redução do diâmetro da microfresa são influenciados pelo avanço da ferramenta e tipo de corte. As maiores reduções no diâmetro (≈11%) foram devido ao impacto periódico da aresta de corte na peça e não pelo efeito de sulcamento (≈4%). Além disso, para o percurso de corte adotado de 98,018 m, com 4,2% da usinagem em sulcamento ou inexistente no corte em face, houve predominância de avarias por lascamento e, para o mesmo percurso, porém, com aproximadamente 14,3% do corte em sulcamento, os fenômenos predominantes no desgaste foram abrasão e adesão. O efeito do sulcamento fez com que os fatores tipo de corte e avanço, bem como suas respectivas interações, fossem significativos sobre a energia específica de corte. Os cortes em cheio e corte concordante com avanço de 3 µm/dente proporcionaram condições mais favoráveis para o microfresamento frontal, com melhor acabamento da peça e menores níveis de desgaste da ferramenta de corte.
Micro-machining is one of the processes feasible for generating geometries or parts with precision and complexity regarding dimensions smaller than 1 mm. However, the achievement of enhanced machining performance and product quality requires a prior understanding on the tool-workpiece interface. This research detemined the influence of cutting type and cutting feed on wear (tool), specific cutting force (process) and surface roughness (workpiece) when cutting the ultrafine-grained steel COS AR60 under end milling strategy. Machining tests were performed in a CNC machining centre Romi D600 provided with a high-speed spindle (60kpm) without cutting fluid application. TiAlN coated carbide endmill (Ø 800 μm) was used for straight cut with 60 m/min cutting speed, 160 μm depth of cut and feed per tooth of 3 and 10 μm. Analysis of Variance (ANOVA) with confidence interval of 95% was applied to the three runs of each cutting sets. The results have shown that tool wear levels and tool effective diameter are influenced by tool feed and cutting type. Hence, intermittent impact of tool’s cutting edges into the workpiece (≈11%) during cutting revealed to be the major cause of tool wear when compared to cutting mechanism dominated by ploughing (≈4%). Regarding experimental sets with cutting length of 98,018 m there was a predominance of tool edge chipping over abrasion and adhesion when performing face cutting with ploughing at 4.2%. On the other hand, if ploughing increases to 14.3% the main wear mechanism observed were abrasion and adhesion. Therefore, there was a significant interaction between specific cutting force and the input parameters of feed per tooth and cutting type. As a result, down-milling and channel-milling at the tool feed of 3 μm/tooth leaded to a valuable cutting performance with better workpiece surface roughness and tool wear at low levels.
Micro-machining is one of the processes feasible for generating geometries or parts with precision and complexity regarding dimensions smaller than 1 mm. However, the achievement of enhanced machining performance and product quality requires a prior understanding on the tool-workpiece interface. This research detemined the influence of cutting type and cutting feed on wear (tool), specific cutting force (process) and surface roughness (workpiece) when cutting the ultrafine-grained steel COS AR60 under end milling strategy. Machining tests were performed in a CNC machining centre Romi D600 provided with a high-speed spindle (60kpm) without cutting fluid application. TiAlN coated carbide endmill (Ø 800 μm) was used for straight cut with 60 m/min cutting speed, 160 μm depth of cut and feed per tooth of 3 and 10 μm. Analysis of Variance (ANOVA) with confidence interval of 95% was applied to the three runs of each cutting sets. The results have shown that tool wear levels and tool effective diameter are influenced by tool feed and cutting type. Hence, intermittent impact of tool’s cutting edges into the workpiece (≈11%) during cutting revealed to be the major cause of tool wear when compared to cutting mechanism dominated by ploughing (≈4%). Regarding experimental sets with cutting length of 98,018 m there was a predominance of tool edge chipping over abrasion and adhesion when performing face cutting with ploughing at 4.2%. On the other hand, if ploughing increases to 14.3% the main wear mechanism observed were abrasion and adhesion. Therefore, there was a significant interaction between specific cutting force and the input parameters of feed per tooth and cutting type. As a result, down-milling and channel-milling at the tool feed of 3 μm/tooth leaded to a valuable cutting performance with better workpiece surface roughness and tool wear at low levels.
Descrição
Palavras-chave
Microusinagem, Desgaste, Energia específica de corte, Sulcamento, Rugosidade, Micromachining, Tool wear, Specific cutting force, Ploughing, Roughness