Performance characterization of shielded metal arc welding power supply designs
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Date
2019-01-28
Authors
Padmanabhan, Rangarajan
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
Engine driven welding power supplies are widely used for Shielded metal arc welding process in field applications such as pipeline industry, where there is a lack of electricity grid. Being a manual process, the welder’s preference towards a DC generator based power supply over a chopper based power supply requires the need for scientific/quantitative evidence to back the reasons for this preference. Due to differences in the mechanism used to control the current, the current pulse profile generated by either machine is different from one another. This difference in the current profile affects the metal transfer phenomenon as well as the arc stability causing difficulty to the welder. Therefore, current and voltage signals collected using high-speed data acquisition system was analyzed and these signals were synchronized with high-speed video in order to observe and explain the mode of metal transfer. The experiments were performed with operators of different experience levels; at different welding positions in order to determine how the characteristic of power supply alone truly affect the current, voltage signals and metal transfer. Auxiliary outputs such as melt-off rates, and the ease of bridging increasing gaps were used for further comparisons between the power supplies. The results showed the predominant mode of metal transfer for either electrodes, E6010 and E7018. Results from heatscatter plots and high-speed videos explain the reasons provided by the welders for their preference towards DC generator based power supply. Lower voltage range provided by the DC generator based power supply explains for the tighter arc produced by it, while the higher current range and rapid arc movement at the tip of the electrode explains the easier arc control and restart-ability provided by the DC generator based power supply. Moreover, at the same average current level for both power supplies, DC generator based power supply produced a better melt-off rate compared to chopper based power supply, affecting the productivity.
Description
Keywords
SMAW, High-speed videos, power supply