Pulsed Wire Feed Research Articles

Hygienic characteristics of mechanized arc welding with pulse flux-cored wire feeding

Purpose. Determination of possibilities of influence of process of arc welding with controlled impulse supply of powder electrode wire on hygienic characteristics of process of welding and choice of welding modes, providing reduction of secretions of harmful substances. Methodology. Investigate the dependence of the indicators of the levels of emissions of harmful substances of the welding aerosol from the welding mode to select the optimal parameters on the example of welding with controlled pulse feed. The key studied parameter was the intensity of welding aerosol release. The research was carried out by the method of "complete capture", based on the principle of filtering the entire volume of air sucked from the shelter on the FPP filter installed on the road. Findings. The advantages and possibilities of reducing emissions of harmful substances into the air of the working area due to the use of welding with pulsed wire feed and the choice of appropriate parameters of welding modes are shown. It is established that the intensity of welding aerosol formation, the number of main components and their mass fraction in the composition of the welding aerosol are sensitive to voltage changes within ± 1.5-2 V, which occurs under the condition of pulsed electrode wire supply. Originality. Hygienically justified use of welding modes with controlled pulse feed of the electrode wire. Practical implications. Mechanized welding with controlled pulse feed of flux-cored wire makes it possible to improve the hygienic characteristics of this process in comparison with welding with continuous wire feed and to some extent to control them. The obtained research results are recommended to be used to improve the working conditions of welders by selecting appropriate welding modes with controlled pulse supply of flux-cored wire. Such optimization of the welder's working conditions can be achieved by fine-tuning the parameters of the pulse supply of the electrode wire and the correct selection of welding materials.

Control of Droplet Transition in Underwater Welding Using Pulsating Wire Feeding.

Underwater wet welding technology is widely used. Because the stability of droplet transfer in underwater wet welding is poor, the feasibility of improving the droplet transfer mode has been discussed from various technical directions. In this work, the characteristics of pulsating wire feeding were studied in the pulsating wire feeding mode by investigating the effects of changing the pulsating frequency, the wire withdrawal speed, and the wire withdrawal quantity on the droplet transfer process and the welding quality. With the aim of improving weld forming and welding stability, the authors selected the coefficient of variation and the ratio of unstable droplet transfer as the indexes to evaluate the effect of droplet transfer control. The pulsating wire feeding process of underwater wet flux-cored wire was analyzed in depth, and the following conclusions were drawn: using the pulsating wire feeding mode and after comparing and analyzing the pulsed wire feeding process under the same frequency condition, the authors found that the forming and stability were better under the conditions of slower withdrawal speed and smaller withdrawal quantity. The short-circuit transition ratio decreased steadily with the increase of pulsating wire feeding frequency, the rejection transition ratio first rose and then decreased, and the splash ratio first decreased and then rose.

Desenvolvimento e Avaliação de Técnicas para Pulsação da Alimentação de Arame em Soldagem a Arco

Resumo Uma das novas abordagens em soldagem é a aplicação de técnicas de alimentação pulsada do arame de adição para TIG e MIG/MAG. Entretanto, tais técnicas necessitam de alimentadores de arame e/ou tochas específicos, o que acaba limitando sua implementação pelo custo destes equipamentos. Assim, o presente trabalho tem como objetivo introduzir e avaliar de forma exploratória técnicas para pulsar a alimentação do arame aplicadas de forma independentemente de alimentadores e/ou tochas especiais. São apresentadas uma técnica com acionamento eletromecânico e outra com eletromagnético. Foram avaliados os efeitos da amplitude e frequência da alimentação pulsada sobre a formação de cordões de solda sobre chapa e sobre os sinais elétricos correspondentes. Para TIG, percebeu-se que a pulsação da alimentação tem potencial para modificar o cordão e tornar mais regular a transferência de material para a poça. Já para MIG/MAG, verificou-se que a pulsação da alimentação pode interferir no processo, sendo capaz de modificar uma transferência metálica globular irregular para regular, reduzindo a corrente média e afetando a formação do cordão. A pulsação da alimentação do arame, mesmo de forma independente de alimentadores e/ou tochas especiais, é então capaz de interferir nos processos, abrindo um campo de desenvolvimento de tecnologias de soldagem derivativas.

Study of metal transfer control in underwater wet FCAW using pulsed wire feed method

A metal transfer control method based on pulsed wire feed technology is adopted to ameliorate the underwater flux-cored arc wet welding quality. The stability of the welding process is improved with appropriate pulse parameters. The influences of pulse parameters on the metal transfer process are clarified using an X-ray transmission method. Pulse frequency has more of an effect on weld appearance and welding stability than pulse duty factor. Thirty to forty hertz is an appropriate frequency bound for a stable metal transfer process. The repelled metal transfer percentage decreases with increasing droplet growth speed. The inertia force shortens the metal transfer period and prompts droplet transfer into the pool. When the pulse frequency is less than 40 Hz, the base speed time is long enough for the inertia force to act on the droplet. But if the pulse frequency is below 20 Hz, the peak wire feed speed will be sustained for a long time, and the short-circuit frequency increases from 1 to 2.5 Hz; as a result, the welding stability and the welding appearance deteriorate. For the wire employed in this study, better welding stability is obtained at 30 Hz, while the pulse duty factor is 2.

A contribution to the study of the cold wire TIG process in the flat, horizontal and overhead position with new torch designs and wire feed methodologies

This line of research aims to improve current procedures in the welding of boiler tubes, where manual welding processes are used and the quality of the welded joints depend exclusively on the welder’s skill. In this connection, what is proposed is to effect repairs with a more productive welding process called cold wire TIG with mechanized feed of cold wire, with the aim of achieving improvements in weldment quality and repeatability. The weld beads were assessed according to surface appearance, morphology, degree of dilution and convexity index. Tests were carried out with two wire guides (20° and 48°) for verifying the influence of the angle of introduction of the wire in the arc. The results indicate a considerable increase in productivity of the TIG process with mechanized wire feed, when the guide developed is employed with a wire entry angle of 20°, approaching the deposition rate obtained with the MIG/MAG process for the same wire diameter. Two configurations of wire feed could be tested: continuous and pulsed. The results showed that the pulsed wire feed configuration proposed was applied successfully in all positions, ensuring repeatability, process stability and stability of the molten pool.

Automatic submerged-arc welding with pulsed electrode wire feed using a stepping motor

Automatic submerged-arc welding using a pulsed wire feed mechanism developed on the basis of a stepping motor is discussed. The results of investigations of the effect of the conditions of pulsed wire feed on the processes of droplet formation at the tip of the electrode, the geometrical parameters of the deposited bead and the surfacing factor are presented.

Uma Contribuição ao Estudo do Processo TIG Cold Wire na Posição Plana, Horizontal e Sobrecabeça sob Novos Desenhos de Tocha e Metodologias de Alimentação de Arame

Resumo Esta linha de pesquisa surge para melhorar o atual procedimento na soldagem de tubos de caldeiras, onde são utilizados processos de soldagem manual e a qualidade das uniões soldadas depende exclusivamente da habilidade do soldador. Neste sentido, a proposta consiste em realizar a reparação com um processo de soldagem mais produtivo denominado de TIG cold wire com alimentação mecanizada de arame frio com a intenção de conseguir ganhos em qualidade nas uniões soldadas e repetitividade. Os cordões de solda foram avaliados pelo aspecto superficial, morfologia, grau de diluição e índice de convexidade. Foram realizados ensaios com dois direcionadores de arame (20° e 48°) para verificar a influência do ângulo de entrada da injeção de arame no arco. Os resultados indicam um aumento considerável da produtividade do processo TIG com alimentação mecanizada de arame, quando é empregado o direcionador desenvolvido com entrada de arame de 20°, aproximando-se a taxa de deposição daquelas obtidas com o processo MIG/MAG, para um mesmo diâmetro de arame. Foi possível testar duas configurações de alimentação de arame: contínua e pulsada. Os resultados mostraram que a configuração de alimentação pulsada de arame proposta foi aplicada com sucesso em todas as posições garantindo repetitividade, estabilidade do processo e sustentabilidade da poça de fusão.

Systems to Control Molten Metal Transfer in Arc Welding

The paper analyzes the systems used for controlling molten wire metal droplets during the arc welding process in shielding gases. The variations for implementing the relevant systems are given, with the positive and negative aspects of such implementation taken into account. Electrical systems are currently investigated to the fullest extent possible and implemented in different power sources for pulsed welding arc. Mechanical systems are represented by different types of feeders that provide the pulsed wire feeding process. The feed mechanisms driven by electric motors and electromagnets are analyzed. In addition to the mechanical and electrical systems, the examples of combined control systems are given.

An automated system for controlling the CO2welding process with pulsed wire feed and welding current modulation

An automated system for consumable electrode welding with pulsed wire feed and arc current modulation is proposed. The flow diagram and the operating principle of automated control of the welding process and also welding equipment are described

Automated system for controlling the process of CO2 welding with pulsed wire feed and welding current modulation

An automated system for consumable electrode welding with pulsed wire feed and arc current modulation is proposed. The circuit diagram and operating principle of automated control of the welding process and also welding equipment are described.