An Experimental Study on Rotating Behavior of Arc during Magnetically Impelled Arc Butt Welding

Abstract

This study intends to make clear experimentally physical reasons why in the case of the steel pipe with thicker wall thickness the arc rotates at low speed in the initial stage of heating and does at high speed in the final stage, why the arc rotates on the inner side of the pipe edge surface in the initial stage, and why the rotating position of the arc moves from the inner side to the outer side of the pipe edge surface as heating time passes. The results obtained were as follows:
1) The low speed rotation of the arc in the initial stage of heating is due to the lower driving force resulted from the lower flux density at the inner side of the pipe edge surface, and the high speed rotation of the arc in the final stage is due to the higher driving force resulted from the higher flux density at outer side.
2) The rotation of the arc on the inner side of the pipe edge surface in the initial stage is caused by the distribution of the magnetic field due to the heating current, according to the geometrical shape, the arrangement and the magnetic property of the pipe and other components for welding.
3) The reason for the moving of the rotating position of the arc from the inner side of the pipe edge surface to its outer side with the increase of heating time is the variation of the magnetic field due to the heating current, which is caused by the magnetic transformation due to temperature rising near the pipe edge.