Device Design for Electric Arc Electromagnetic Constriction

Abstract

The difference of potential between two electrodes results in electric current breaking the dielectric barrier of the gas in this space causing a plasma discharge called electric arc. As a result, there is luminosity and an increase in temperature. Electric arc is used for welding and usually one of the electrodes is cylindrical with small diameter and the other with large area. Because of this configuration, the side section of the electric arc has a bell shape and forms a circular impression in contact with the work piece (the weld pool). With the use of electromagnetic forces, it is possible to change this circular impression, completely changing the behavior and consequently the geometry of the weld pool. This article presents the development and construction of a device for the electromagnetic constriction of the electric arc, capable of changing the cross section of the impression from circular to elliptical. The steps performed in the article were the simulation of the electromagnetic fields generated to change the electric arc shape, the development of the arc constriction device and the application of this electromagnetic constriction in beads on plate. The results show that the electromagnetic forces change the transverse profile of the arc from circular to elliptical, enabling the increase in specific power and a more precise orientation of the electric arc. Also, changing the orientation of the ellipse results in different penetration and width of the bead.