Stability of the Welding Arc in a Constant Feeding Speed System

Abstract

This paper deals with some problems concerning the stability of the D. C. arc welding system in which the electrode wire is fed with a constant speed. The arc welding system may produce a self-sustained oscillation where the current and length of the arc vary slowly and periodically in the steady state. The welding system is described by nonlinear differential equations. The phase-plane analysis is applied to the study of the phenomena. A steady state having a constant arc length is correlated with a singular point. A self-sustained oscillation is then represented by a limit cycle in the phase-plane. From the analytical results, it may be inferred that the self-sustained oscillations occur due to the self-regulation peculiar to the arc in the case where the power source has a rising characteristic.