Evaluation of strategies for milling of thin-walled aluminum components

• Ano de defesa: 2014
• Autor(a) principal: Rafael Borges Mundim
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Instituto Tecnológico de Aeronáutica
• Palavras-chave em Português: Fresagem (usinagem); Produtividade; Qualidade; Ferramentas de corte; Peças mecânicas; Partes de motores; Engenharia mecânica
• Link de acesso: http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=2962

A considerable amount of research has focused on machining dynamics due to the impact it lays upon productivity and quality. Models have been developed with an ever-increasing accuracy in order to predict the dynamic behavior of cutting tools under different circumstances. However, workpiece behavior during machining is also a current limiting factor which is dealt with by means of restricting product designers of using features with thin characteristics. For this reason, designed products will be often oversized due to machining technology restrictions related to dimensions of thin walls. The main objective of this work is to investigate the behavior of thin walls during milling in order to identify the challenges imposed by the process. Different strategies are tested and evaluated through force signals, finite element analysis (FEA), analytical models, and analysis of the machined parts. Cantilever walls with varying dimensions are tested and the height-to-thickness (H/t) ratio often found in literature as a guideline is discussed. Waterline, low stock, constant force, and passive damping strategies are evaluated and their applicability, advantages, and restrictions are discussed. The effect of cutting speed on cutting force is investigated from a force and excitation frequency standpoint. A method for prediction of resonance based on a frequency chart is proposed, for which variable speed tests are conducted. This variable speed approach is based on prediction of stable paths as machining progresses by means of the proposed chart. Validation of the frequency chart construction method is presented along with its applicability and restrictions considering a more complex geometry. Results indicate that the frequency chart method can be used to predict and explain the occurrence of instability but limiting factors still lie in implementing and improving the proposed method.