Eletrodos de W-Cu para máquinas de treliças
Data
2022-07-28
Autores
Dias, Gabriel Silva 
Orientadores
Albers, Ana Paula Fonseca
Tipo
Trabalho de conclusão de curso
Título da Revista
ISSN da Revista
Título de Volume
Resumo
Amplamente utilizadas na construção civil, as treliças reforçam a estrutura e auxiliam na diminuição da carga nos elementos estruturais, e com isso também na diminuição do custo dos projetos. As treliças são fabricadas por meio da soldagem eletro-resistiva dos fios de aço CA-60, processo no qual se utiliza eletrodos de W-Cu, que são submetidos a um grande esforço mecânico, sofrendo com desgaste. O objetivo deste trabalho foi compreender as condições de operação desses eletrodos, buscar fundamentação teórica sobre o material que os constitui e elencar as propriedades necessárias para um bom desempenho dos eletrodos de W-Cu na fabricação de treliças. De maneira complementar, realizou-se caracterizações químicas, mecânicas e microestruturais em eletrodos utilizados na produção de treliças da empresa Gerdau localizada na cidade de São José dos Campos, com o objetivo de elaborar uma especificação técnica para os eletrodos de W-Cu e definir uma metodologia de recebimento de material que possa ser utilizada para garantir que os eletrodos recebidos estão de acordo com as especificações. Diante dos resultados obtidos, propôs-se duas especificações técnicas, uma para os eletrodos superiores e outra para os inferiores, baseadas nas propriedades de composição química, densidade, dureza e condutividade. Para os eletrodos superiores que não sofrem tanto com o processo abrasivo, o teor de Cu especificado foi de 30%, com densidade aparente de 14,20 ± 0,20 g/cm³, dureza 90,0 ± 5,0 HRB e condutividade elétrica na faixa de 44,0 - 52,0 % IACS. Para os eletrodos inferiores onde o processo abrasivo é intenso, especificou-se teor de Cu de 20%, com densidade aparente de 15,30 ± 0,20 g/cm³, dureza 102,0 ± 5,0 HRB e condutividade elétrica na faixa de 42,0 - 50,0 % IACS. Por meio da medição da densidade aparente usando o princípio de Archimedes, pode-se inferir indiretamente as demais propriedades presentes na especificação e, portanto, será a propriedade a ser medida no recebimento do material. Os ensaios de condutividade e dureza podem ser utilizados em complementariedade, apresentando-se como alternativas viáveis que podem contribuir na garantia de confiabilidade da aferição.
Widely used in civil construction, the trusses help to reduce the load on the structural elements and thus also reduce the cost of projects. The trusses are manufactured by electro-resistive welding of CA-60 carbon steel rebars, a process in which W-Cu electrodes are used, which are carried out with a great mechanical effort, suffering from wear. The objective of this work is to understand the operating conditions of these electrodes, list performance requirements, seek theoretical foundation about the material that constitutes them, seeking to understand the necessary properties for a good performance of W Cu electrodes in the fabrication of trusses. In a complementary way, will be done chemical, mechanics and microstructures characterizations in electrodes used in the production of trusses in a factory located in the city of São José dos Campos, with the objective of reaching a technical specification for the W-Cu electrodes and define a measurement methodology that can be used to ensure that the electrodes are being received according to the defined specifications. In view of the results obtained, two technical specifications were proposed, one for the upper electrodes and another for the lower ones, based on the properties of chemical composition, density, hardness and conductivity. For the upper electrodes that do not suffer so much from the abrasive process, the Cu content specified was 30% with an apparent density of 14.20 ± 0.20 g/cm³, hardness 90.0 ± 5.0 HRB and electrical conductivity in the range of 44.0 – 52.0 %IACS. For the lower electrodes where the abrasive process is intense, a Cu content of 20% was specified, with an apparent density of 15.30 ± 0.20 g/cm³, hardness 102.0 ± 5.0 HRB and electrical conductivity in the range of 42.0 – 50.0 %IACS. By measuring the apparent density using the Archimedes principle, one can indirectly infer the other properties present in the specification and, therefore, it will be the property to be measured upon receipt of the material. The conductivity and hardness tests can be used in complementarity, presenting themselves as viable alternatives that can contribute to guarantee the reliability of the measurement.
Widely used in civil construction, the trusses help to reduce the load on the structural elements and thus also reduce the cost of projects. The trusses are manufactured by electro-resistive welding of CA-60 carbon steel rebars, a process in which W-Cu electrodes are used, which are carried out with a great mechanical effort, suffering from wear. The objective of this work is to understand the operating conditions of these electrodes, list performance requirements, seek theoretical foundation about the material that constitutes them, seeking to understand the necessary properties for a good performance of W Cu electrodes in the fabrication of trusses. In a complementary way, will be done chemical, mechanics and microstructures characterizations in electrodes used in the production of trusses in a factory located in the city of São José dos Campos, with the objective of reaching a technical specification for the W-Cu electrodes and define a measurement methodology that can be used to ensure that the electrodes are being received according to the defined specifications. In view of the results obtained, two technical specifications were proposed, one for the upper electrodes and another for the lower ones, based on the properties of chemical composition, density, hardness and conductivity. For the upper electrodes that do not suffer so much from the abrasive process, the Cu content specified was 30% with an apparent density of 14.20 ± 0.20 g/cm³, hardness 90.0 ± 5.0 HRB and electrical conductivity in the range of 44.0 – 52.0 %IACS. For the lower electrodes where the abrasive process is intense, a Cu content of 20% was specified, with an apparent density of 15.30 ± 0.20 g/cm³, hardness 102.0 ± 5.0 HRB and electrical conductivity in the range of 42.0 – 50.0 %IACS. By measuring the apparent density using the Archimedes principle, one can indirectly infer the other properties present in the specification and, therefore, it will be the property to be measured upon receipt of the material. The conductivity and hardness tests can be used in complementarity, presenting themselves as viable alternatives that can contribute to guarantee the reliability of the measurement.