Double-electrode arc welding process: Principle, variants, control and developments

Abstract

Double-electrode gas metal arc welding (DE-GMAW) is a novel welding process in which a second electrode, non-consumable or consumable, is added to bypass part of the wire current. The bypass current reduces the heat input in non-consumable DE-GMAW or increases the deposition speed in consumable DE-GMAW. The fixed correlation of the heat input with the deposition in conventional GMAW and its variants is thus changed and becomes controllable. At the University of Kentucky, DE-GMAW has been tested/developed by adding a plasma arc welding torch, a GTAW (gas tungsten arc welding) torch, a pair of GTAW torches, and a GMAW torch. Steels and aluminum alloys are welded and the system is powered by one or multiple power supplies with appropriate control methods. The metal transfer has been studied at the University of Kentucky and Shandong University resulting in the desirable spray transfer be obtained with less than 100 A base current for 1.2 mm diameter steel wire. At Lanzhou University of Technology, pulsed DE-GMAW has been successfully developed to weld aluminum sheets. At the Adaptive Intelligent Systems LLC, DE-GMAW principle has been applied to the submerged arc welding (SAW) and the embedded control systems needed for industrial applications have been developed. The DE-SAW resulted in 1/3 reduction in heat input for a shipbuilding application and the weld penetration depth was successfully feedback controlled. In addition, the bypass concept is extended to the GTAW resulting in the arcingwire GTAW which adds a second arc established between the tungsten and filler to the existing gas tungsten arc. The DE-GMAW is extended to double-electrode arc welding (DE-AW) where the main electrode may not necessarily to be consumable. Recently, the Beijing University of Technology systematically studied the metal transfer in the arcingwire GTAW and found that the desired metal transfer modes may always be obtained from the given wire feed speed by adjusting the wire current and wire position/orientation appropriately. A variety of DE-AW processes are thus available to suit for different applications, using existing arc welding equipment.

Application of Pulsed Laser-TIG Hybrid Heat Source in Root Welding of Thick Plate Titanium Alloys

“…So it is important to control the shape of the back molten pool by adjusting the temperature distribution over the top of the molten pool. According to manual arc welding for one side welding with back formation, the arc distribution on the molten pool front rim plays a decisive role in weld bead formation on the back side [24][25][26][27].…”

Arc characteristics and metal transfer modes in arcing-wire gas tungsten arc welding

“…A highspeed camera, equipped with a 940-nm filter and operating at 500 frames per second (fps), was installed perpendicular to the plane determined by the welding direction and integrated torches. [4,6] In the experiments, the main arc started first and the bypass arc followed closely. The GMAW torch was leading, and the GTAW followed behind in experimental group 1 and group 2.…”

“…1a) and arc-assisted hotwire GTAW (Fig. 1b) are two approaches that commonly use a preheated wire [5,6]. The wire feeder is independent from the GTAW power source, and there is another preheating power source to apply current to the wire or to produce an arc between the auxiliary GTAW torch and wire.…”

“…Arcing-wire GTAW, which is a GTAW variation, is an innovative welding process inspired by the double-electrode arc welding process [6,7]. The arcing-wire GTAW (Fig.…”

“…The arcing-wire GTAW (Fig. 2b) process [4,6], in which the bypass arc melts the wire directly, differs from traditional hot-wire GTAW (Fig. 2a) in the melting mode of filler wires.…”