Abstract: Apparatus for supporting and feeding high frequency electric current to a pair of contacts for engaging a work piece or pieces and supplying current thereto in which a co-axial line has relatively movable inner and outer conductors with a pair of contacts respectively mounted at one end of each conductor, electric current being supplied to the conductors adjacent the other ends of the conductors. In one embodiment, the conductors are rotatable and the contacts are mounted on radially extending arms secured to the ends of the conductors. In other embodiments, one conductor is rotatable and the other conductor is axially movable, one contact being mounted on a radially extending arm secured to the rotatable conductor and the other contact being secured to the end of the axially movable conductor. Also, flexible lead and conductive bearing current feed systems and contact mounting arms which are readily convertible into an induction coil support.

Abstract: A welded seam between overlapped edges of sheet material wherein the sheet material is heated to a temperature below the melting temperature and is forced together under high pressures to form a forged weld. The thickness of the sheet material in the weld area is reduced from double thickness to a thickness approaching a single thickness, with the weld interface being diagonally disposed. The weld is effected by grain growth across the interface such that the particular line along which the meeting surfaces of the metal are welded together is unobservable upon etching a cross section thereof and with magnification on the order of 100X. The heating is effected by applying to opposing edge portions which are to be overlapped and welded a high frequency current which effectively reduces heating to edge portions only of the metal with the heat effected area being in the vicinity of 0.1 inch.