Air cooled magnetic structure for use in high frequency welding and heating

Claim 1

Apparatus for controlling the path of high frequency current flowing in one or more workpieces, comprising means connected to a source of high frequency current for establishing a high frequency current path in a portion of a surface of said one or more workpieces, a magnetic structure disposed closely adjacent and extending along at least a portion of the desired path of said current to control the width of the desired path, said structure being comprised of a plurality of laminations of magnetic material disposed in closely packed relationship and extending transversely to the direction of said path, all of the laminations in said structure being similarly shaped and having one peripheral region disposed closely adjacent said surface of said workpiece and said current path but spaced from said current path a distance greater than the spacing between said region and said surface, alternate ones of the plurality of laminations in said structure having a second peripheral region spaced from said one peripheral region in a direction away from said surface which differs in size and or shape from the closest corresponding peripheral region of a next adjacent lamination in the structure, said alternate ones of the laminations being distributed throughout the structure to provide alternately occurring radiating surfaces and coolant passages throughout an exterior portion of the structure, and means for directing a fluid coolant onto said exterior portion of the structure thereby to cool the structure.