Importance

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Abstract

In a plasma arc torch, an electrode is movable axially into and out of electrical connection with an anode, typically a nozzle secured to one end of a torch body. A flow of pressurized plasma gas is directed to a plasma chamber between the electrode and the nozzle, preferably through a replaceable swirl ring that closely surrounds and guides the electrode at a larger diameter shoulder portion of the electrode. A gas flow passage, preferably a spiral passage machined on the outer side surface of the shoulder portion, diverts a portion of the gas flow from the plasma chamber to a region above the electrode where it is vented to atmosphere. The passage is sufficiently constricted that a substantial pressure drop appears along the path, while at the same time allowing a sufficient flow to produce the desired cooling. The revolutions of the spiral are preferably closely spaced to enhance the surface area of the electrode in a heat transfer relationship with the cooling gas flow.

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First Claim