Method of and device for plasma-MIG welding
AssigneeU.S. Philips Corporation
InventorGerardus A. M. Willems
Life of this patent
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Abstract
Plasma-MIG welding in which a thermally ionizable inert gas stream is flowed through a nozzle non-consumable electrode having a central aperture and a surrounding annular aperture toward a workpiece and is thereby split into a central gas column enveloped by an annular gas shield. A consumable electrode is fed through the central gas column toward the workpiece, with the establishment of a MIG-arc therebetween. A plasma arc is spontaneously established by means of the MIG-arc between the nozzle non-consumable electrode and the workpiece.
Claims4
A method of plasma-MIG welding, which comprises providing a single nozzle non-consumable electrode having a central aperture and a surrounding annular aperture;
- flowing a thermally ionizable gas stream from a common gas source through said single nozzle non-consumable electrode toward a workpiece, said single nozzle splitting said gas stream into a central gas column surrounded by a parallelly flowing annular gas sheath, said annular gas sheath and said central gas column having the same composition as they flow past the outlet of said single nozzle;
- feeding a consumable electrode through said central gas column toward the workpiece;
- first establishing a MIG-arc between said consumable electrode and said workpiece;
- and then spontaneously establishing a plasma arc by means of said MIG-arc between said single nozzle non-consumable electrode and said workpiece to ionize said central gas column and sustain a plasma flow enveloping said MIG-arc, the surrounding annular gas sheath remaining non-ionized.
A plasma-MIG welding torch, which comprises a cylindrical housing;
- a cylindrical support electrically connected to the interior of said cylindrical housing;
- a single nozzle non-consumable electrode positioned adjacent one end of said cylindrical support, said single nozzle comprising a central ring and a plurality of ribs extending radially from said central ring to said cylindrical support and providing electrical connection therebetween;
- means for flowing a thermally ionizable gas stream from a common gas source through said single nozzle non-consumable electrode toward a workpiece to thereby split said gas stream into a central gas column surrounded by a parallelly flowing annular gas sheath both having the same composition as they flow past the single nozzle outlet;
- means for feeding a consumable electrode through said central gas column toward the workpiece;
- a first circuit means consisting basically of said consumable electrode, a first power supply, and said workpiece for establishing a MIG-arc between the consumable electrode and the workpiece;
- and a second circuit means consisting basically of a second power supply, said single nozzle non-consumable electrode, and said workpiece for establishing a plasma arc between the single nozzle non-consumable electrode and the workpiece to ionize said central gas column and sustain a plasma flow enveloping said MIG-arc without ionizing the surrounding annular gas sheath.
Dependencies are inferred from the claim text.