Some studies on the electromagnetic aspects governing the magnetically impelled arcs through experimentation, finite element simulation and statistical analysis

Abstract

In this study, Magnetically Impelled Arc Butt welding (MIAB) laboratory setup for welding carbon steel tubes of small wall thickness is designed and developed. Magnetically Impelled Arc Butt welding is an efficient two phase process which is used in highly automated factory production lines in high volume industries such as automotive manufactures. In this process, an electric arc generated between aligned and properly gapped pipes are made to rotate along the peripheral butt ends. This arc swiftly rotates along the peripheral edges of the tubes to be welded due to the electromagnetic force resulting from the interaction of the arc current and the externally controlled magnetic field created by magnetic systems. The arc acts as a heating source providing the required heat to the butt ends of the pipes. Further an application of force on the pipe along the axial direction sets the weld. The electromagnetic force responsible for the arc rotation is governed by the magnetic flux density in the gap, the arc current and the arc length (gap size). To be precise the radial magnetic flux density is a critical factor in arc rotation and weld quality. Preliminary trials are conducted to understand the process parameters. Tubes with 45 mm Outer Diameter with 3 mm thickness are used for conducting the investigations. Further, for the first time an attempt is made to analyze the effects of weld input parameters such as welding current, welding voltage, magnetic coil voltage and magnetic coil current on the arc speed in MIAB welding process using software package STATA. The aim of this study also is to explore the distribution of the magnetic flux density in the tube gap region using finite element code ANSYS .The analysis emphasizes that the most significant factor that governs the arc speed is magnetic coil current (that creates magnetic flux density) and the welding current.