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Advisor(s)
Abstract(s)
A presente dissertação tem como principal objetivo a realização de um estudo de otimização de
parâmetros no processo de soldadura por pontos em dois materiais, aço St12 e alumínio 1050, com
base no Método de Taguchi. Este processo consiste na ligação de dois componentes, normalmente
em chapa, através de uma corrente elétrica transmitida por dois elétrodos, sendo este um processo
de rápida aplicação e desta forma, de elevada importância nas indústrias automóvel e aeroespacial.
Na revisão do estado da arte foi estudado o funcionamento do processo, assim como as suas
principais variantes, vantagens e desvantagens. Posteriormente, e de forma a permitir um
aprofundamento da componente prática, foi realizada uma revisão sobre os métodos de ensaio,
destrutivos e não destrutivos, aplicáveis neste tipo de juntas e formas de avaliar a qualidade da
soldadura resultante. A escolha do ensaio de submissão do ponto de soldadura a um esforço de
corte, foi a base para o posterior estudo dos parâmetros mais influentes no processo e a sua
influência na resistência mecânica e microdureza, permitindo assim concluir os parâmetros mais
importantes a estudar na componente prática, e as variáveis que se iriam posteriormente definir
para este estudo. Um estudo do método de Taguchi aplicado a este processo de soldadura foi
também realizado, uma vez que este método de análise estatística de resultados foi aplicado. O
método de Taguchi permitiu, em ambos os materiais, identificar a melhor combinação de
parâmetros a aplicar, sendo que ocorreu a variação de um dos parâmetros entre os diferentes
materiais. A corrente de soldadura e tempo de soldadura foram mantidos sendo utilizada a
espessura de chapa e a temperatura de pré-aquecimento como terceiros parâmetros selecionados
para os materiais da família do aço e alumínio, respetivamente. O resultado comparador para os
diferentes parâmetros aplicados no método de Taguchi foi a força máxima aos quais os provetes se
encontraram sujeitos no ensaio de corte.
The main objective of this dissertation is to carry out a study on the optimization of parameters in the spot-welding process in two materials, St12 steel and 1050 aluminium, based on the Taguchi Method. This process consists in the connection of two components, normally in sheet metal, through an electric current transmitted by two electrodes, being this a process of fast application and of high importance in the automotive and aerospace industries. In the review of the state of the art the operation of the process was studied, as well as its main variants, advantages, and disadvantages. Subsequently, and to allow a more profound study of the practical component, a review of the destructive and non-destructive test methods applicable to this type of joints and ways to evaluate the quality of the resulting weld was carried out. The choice of the welding point shear strength test was the basis for the subsequent study of the most influential parameters in the process and their influence in the mechanical resistance and microhardness, thus allowing the conclusion of the most important parameters to be studied in the practical component and the variables that would be defined later for this study. A study of the Taguchi method applied to this welding process was also carried out, as this method of statistical analysis of results was applied. The Taguchi method allowed, in both materials, to identify the best combination of parameters to be employed, with the variation of one of the parameters occurring between the different materials. Welding current and welding time were maintained and sheet thickness and preheating temperature were used as third selected parameters for the steel and aluminium family of materials respectively. The comparator result for the different parameters applied in the Taguchi method was the maximum force to which the specimens were subjected in the shear strength test.
The main objective of this dissertation is to carry out a study on the optimization of parameters in the spot-welding process in two materials, St12 steel and 1050 aluminium, based on the Taguchi Method. This process consists in the connection of two components, normally in sheet metal, through an electric current transmitted by two electrodes, being this a process of fast application and of high importance in the automotive and aerospace industries. In the review of the state of the art the operation of the process was studied, as well as its main variants, advantages, and disadvantages. Subsequently, and to allow a more profound study of the practical component, a review of the destructive and non-destructive test methods applicable to this type of joints and ways to evaluate the quality of the resulting weld was carried out. The choice of the welding point shear strength test was the basis for the subsequent study of the most influential parameters in the process and their influence in the mechanical resistance and microhardness, thus allowing the conclusion of the most important parameters to be studied in the practical component and the variables that would be defined later for this study. A study of the Taguchi method applied to this welding process was also carried out, as this method of statistical analysis of results was applied. The Taguchi method allowed, in both materials, to identify the best combination of parameters to be employed, with the variation of one of the parameters occurring between the different materials. Welding current and welding time were maintained and sheet thickness and preheating temperature were used as third selected parameters for the steel and aluminium family of materials respectively. The comparator result for the different parameters applied in the Taguchi method was the maximum force to which the specimens were subjected in the shear strength test.
Description
Keywords
Welding Taguchi Parameters Steel Aluminium