Patent ID: 8110772
Filing Date: 2012-02-07
Classification: B23K

Abstract:
1. An improved method for multi-pass computer controlled narrow-gap Electroslag welding applications comprising, the method comprising the following steps: a) providing at least one pair of workpieces having upper ends and lower ends, the workpieces positioned to be welded together defining a welding gap of uniform width between the at least one pair of workpieces and defining a welding gap height, the welding gap further defining a welding gap centerline and welding gap sides; b) providing at least one insert-weld air-cooled welding shoe inserted in the welding gap for the length of the welding gap height; c) providing at least one butt-weld air cooled welding shoe on the exterior of the welding gap for the length of the welding gap height; d) providing means for Electroslag welding within the welding gap between the at least one pair of workpieces, said means for Electroslag welding within the welding gap between the at least one pair of workpieces comprising at least one sump bridging the lower ends of the at least one pair of workpieces and serving as a basin for the welding gap width, at least one plate bridging the welding gap width at the at least one pair of workpieces upper ends, and at least one constant voltage, square wave AC welding power supply; and e) providing means for controlling Electroslag welding within the welding gap between the at least one pair of workpieces such that a heat transfer depth penetration from an Electroslag weld puddle to the workpieces follows a pre-determined profile resulting in a smaller heat affected zone and smaller grain structure in the weld metal and such that the magnetic field within the welding gap is reduced or eliminated allowing the weld to stay in the center of the welding gap with balanced penetration on all sides of the welding gap reducing or eliminating the potential to short-circuit and stop the process in the middle of a weld cycle and whereby all air-cooled welding shoes are maintained at a temperature range between 800 degrees Fahrenheit to 1000 degrees Fahrenheit during the Electroslag welding operation.