Patent ID: 6156999
Filing Date: 2000-12-05
Classification: B23K

Abstract:
A method of igniting a welding arc of an arc welding apparatus by a high voltage discharge between a welding electrode and a workpiece, the method comprising the steps of:(a) connecting the welding electrode and the workpiece with a welding power source;(b) simultaneously connecting the welding electrode and the workpiece with at least a first and a second high voltage power sources;(c) applying a short a periodic high voltage pulse from said first high voltage power sources to an air gap being between the welding electrode and the workpiece, for breaking down, by electric discharge, said air gap, for creating an electroconductive duct therethrough, an output current of said first high voltage power source is restricted in amplitude and rate of rise;(d) superimposing said short a periodic high voltage pulse by another, long, high voltage pulse from said second high voltage power source, said long, high voltage pulse having a current rate of rise smaller than that of said short a periodic high voltage pulse, for generating a stretched pulse, thereby increasing a duration of said discharge current, heating said current conducting duct, reducing its electric resistance and igniting an arc thereat; and(e) reducing a voltage value in said current conducting duct to a value less than that of an open circuit voltage value of said welding power source, thereby effecting a current flow from said welding power source via said welding electrode and said arc to the workpiece and developing a welding arc burning from said welding power source.