Effective power of a constricted welding arc with heteropolar current pulses

Abstract

The authors reviewed the research works on the effective power of direct and reverse polarity welding arcs with a non-consumable electrode in argon. The study shows that it is difficult to use the arc effective efficiency for effective power determination. It applies to the constricted arc more than to the free one. Based on data analysis for the effective power of polarities and the effective efficiency of a constricted arc burning toward the cooper heat flow calorimeter, the authors calculated the specific effective power of polarities and arc stresses. The maximum values are 23.2 W/A for the reverse polarity arc; and 14.2 W/A for the direct polarity arc. The study identified that the decrease in the specific effective power of polarities at the current increase within 100–150 A is well described by linear dependencies. With the current increase, there is a linear decrease in the direct polarity arc stress, while the reverse polarity arc stress remains constant. The spread of data for the specific effective power of polarities is about two times less than the spread for effective efficiency. Using a 2D mathematical model of the constricted arc column in a closed area, the authors calculated the power absorbed by plasma-forming argon and nozzle walls. As a result, the authors obtained the dependencies of the power transferred by argon on the nozzle channel length and the arc current. The specific effective power of argon flow for analyzed current densities and argon consumption shows poor dependence on the arc current and is equal to 5.5 W/A approximately. The power contribution of plasma-forming argon to the effective power of the constricted arc increases with the current increase.