Avaliação de Processos GMAW Duplo-Arame em Baixa Corrente com Controle do Formato de Onda e com Auxílio de Feixe de Laser / Assessment of Low Current Tandem GMAW Processes with Waveform Control and with Aid of Laser Beam

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

In face of manufacturing-related limitations in the present-day industry, the welding sector has looked for new, or even not so new, processes. In other words, it has invested in the development of new processes and, especially, in the use of new arrangements for conventional processes. Thus, the aim of this work was to assess the use of combined processes and techniques as means of overcoming welding-related manufacturing limitations. In order to achieve this target, different tandem GMAW versions were assessed concerning welding current waveform control by developing dedicated softwares. The highspeed welding potential of a tandem process was coupled with the penetration control ability of controlled short-circuit and/or pulsed transfer modes. A combination of tandem GMAW with Laser beam welding was also assessed. As a consequence of difficulties faced in tandem GMAW, an investigation on arc interruptions was carried out by using electromagnetic fields to blow out the arcs. The tandem GMAW versions with both wires operating in controlled short-circuit mode and also with controlled short-circuit mode in the leading wire and pulsed mode in the trailing wire were highly unstable because of the intense interaction between the arcs and the weld pool. The tandem GMAW version with pulsed mode (low mean current) in both wires presented disturbances and interruptions, but such events were circumvented by using a very small delay between the current pulses of each wire. As the tandem pulsed GMAW was the only approach that showed practicability, it was combined with Laser beam welding. This hybrid process was able to increase the maximum welding travel speed or penetration depth significantly in comparison to tandem pulsed GMAW. The Laser beam showed to aid the tandem GMAW process, but more efficiently if placed half way between the wires. In relation to the investigation on arc interruptions, the higher the arc welding current and the shorter the arc length, the more the arc resists to the extinction. High-frequency current pulsing decreased the arc resistance to extinction. A model to explain the arc interruptions was proposed based on a heat balance in the arc column. Eventually, recommendations for future developments are presented

ASSUNTO(S)

controle do formato de onda engenharia mecanica interrupção de arco tandem gmaw soldagem híbrida arc interruption waveform control laser-gmaw soldagem hybrid welding gmaw duplo-arame

ACESSO AO ARTIGO

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