Abstract: A method of severing a metal piece into parts in which electrical contacts engage the piece at the end of the severing line and high frequency electrical current is fed to the contacts for the length of time required to at least significantly reduce the tensile strength of the metal along the line, the current being fed to at least one of the contacts through a proximity conductor overlying the line. After such heating of the metal, the portions of the piece can merely be pulled apart. If shaping of the edge faces is desired, they can be pressed together while heated and malleable and after separation or can be pressed against an anvil while heated and malleable. Before separation, the portions on opposite sides of the line can be pushed toward each other or be moved transversely to each other. If the metal along the line is heated to "burning" temperature, the portions can be separated by burning out the heated metal with an oxygen containing gas.

Abstract: Method and apparatus for butt welding the edge faces of metal skelp which has been heated to a temperature of at least 1000.degree. F. but below the welding temperature of the metal of the skelp. The skelp is continuously advanced through a furnace in which the skelp is heated to such temperature and then, to forming rolls where the skelp is formed into a substantially complete tube with closely spaced skelp edge faces, to a spacing roll for maintaining the edge faces in closely-spaced relation and to pressure rolls where the edge faces are pressed together. Intermediate the spacing roll and the pressure rolls, the edge faces are heated to welding temperature with an induction coil fed with electrical current having a frequency of at least 10 Khz. The induction coil does not encircle the skelp in its tubular forms and instead, has legs adjacent the edge faces and at opposite sides of the gap between the edge faces.

Abstract: Method and apparatus for manufacturing heat exchanger elements in which metal tubing and metal strip are advanced toward each other to a weld station where they are welded together and the tubing-strip combination are then advanced through a first tube straightener, pulling apparatus, a strip corrugator and second tube straightener. The tubing is also passed through tube straightening and shaping apparatus in advance of the weld point. If the combination is collected after leaving the second straightener, the apparatus which is downstream of the weld point other than the pulling apparatus, is inoperative during the advance of the combination therethrough but the combination is then advanced in the reverse direction through such apparatus which is then operative and cut-off apparatus intermediate the weld point and the first straightener cut the combination into panel element lengths which are transferred to further processing apparatus.

Abstract: Heat exchanger elements, particularly for solar panels, comprising metal tubing secured to a metal strip which is wider than the tubing and relatively thin by a weld which is metal of at least one of the tubing and the strip which has melted and cooled, the welding conditions being selected so that molten metal is expelled from between the tubing and the strip at the ends of short intervals and the strength of the weld varies longitudinally of the tubing. High frequency electric welding is used under conditions which cause the expulsion of the molten metal.

Abstract: Method and apparatus for manufacturing a heat exchanger element which comprises a metal tube secured to a metal sheet by metal which has been heated and cooled. Wrinkles in the sheet after the tube has been joined thereto are removed by stretching at least the tube by an amount sufficient to cause the length of the tube to be substantially equal to the length of the outboard edges of the tube. The sheet may also be stretched beyond its elastic limit at the time that the tube is stretched but should not be stretched more than 2.5%.

Abstract: Methods and apparatus for the welding and heat treating of metal parts in which an electric arc extends between a pair of adjacent metal parts or between an electrode and one or more metal parts with the arc traversing the metal part or parts a plurality of times during the heating cycle. For finite length metal parts, i.e. when the surface or surfaces to be heated do not provide closed paths to be followed by the arc, the arc is initiated, caused to follow the surface, extinguished and then reinitiated, or is caused to traverse the surfaces in alternately opposite directions after initiation. With finite length metal parts, run-off tabs are provided at the ends of the surfaces to prevent overheating at such ends. A magnetic field causes the arc to traverse the surfaces and may be modified in strength or distribution to vary traverse rate.

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 method and apparatus for modifying the surface properties of a metal part in which electric current having a frequency of at least 3000 Hz is supplied to a narrow area on the part by means of contacts, one at each end of the area, and a proximity conductor or is induced therein by an induction coil until the metal in the area reaches a temperature at least equal to its melting temperature. A material which will alloy with the metal of the part is added to the molten metal so that when the molten metal is cooled an area of an alloy of the metal and the added material is produced. The added material may be in the form of a gas, powder, salt, wire, rod, bar, foil, etc. and may be applied to the area before, during, or after the melting of the metal of the area. The spacing between the proximity conductor or the induction coil and the work is no greater than three times the width of the proximity conductor or the coil conductor.

Abstract: Method and apparatus for welding a metal part, e.g. a tube or strip, to a thin, flexible metal strip using high frequency electric currents in which the part and strip are continuously advanced to a weld point where they are pressed together. In advance of the weld point, high frequency current is supplied to the part and the strip through contacts engaging them so that portions thereof are heated to welding temperature by the time they reach the weld point. From the point of engagement of the contact with the strip or strips to the weld point the strip material is maintained in a fixed path by a rigid member against which the strip is pressed by tensioning the strip with a pad frictionally engaging the strip. If desired, the current may be fed to the contact engaging the part through a proximity conductor to increase the heating of the part relative to the strip.

Abstract: Methods and apparatus for the welding and heat treating of metal parts in which an electric arc extends between a pair of adjacent metal parts or between an electrode and one or more metal parts with the arc traversing the metal part or parts a plurality of times during the heating cycle. For finite length metal parts, i.e. when the surface or surfaces to be heated do not provide closed paths to be followed by the arc, the arc is initiated, caused to follow the surface, extinguished and then reinitiated, or is caused to traverse the surfaces in alternately opposite directions after initiation. With finite length metal parts, run-off tabs are provided at the ends of the surfaces to prevent overheating at such ends. A magnetic field causes the arc to traverse the surfaces and may be modified in strength or distribution to vary traverse rate.

Abstract: Method and apparatus for modifying the surface properties of a metal part made of a metal which changes its properties with heating to a transformation temperature and subsequent cooling in which method electric current having a frequency of at least 3000 Hz is supplied to a pair of contacts respectively at the opposite ends of the surface area to be modified through a proximity conductor or conductors which are spaced from the surface area by not more than two times the width of the conductor. The duration, frequency and magnitude of the current and the width of the proximity conductor or conductors are chosen so that the metal of such area heats at least to the transformation temperature before the adjacent metal reaches a temperature which would prevent self-quenching of the area metal, by means of conduction of heat from the area metal to the adjacent metal, when the current is discontinued. Apparatus for producing lines of hardening on valve seats is disclosed.

Abstract: In-line electrical welding apparatus for welding small diameter, thin-walled, metal tubing as it is advanced longitudinally comprising a high frequency electrical current source, a pair of upstream electrical contacts connected to one terminal of the source and a pair of downstream electrical contacts connected to the other terminal of the source through a proximity conductor which extends in close relation to the edges of the tubing to be heated from the downstream contacts to adjacent the upstream contacts. The contacts are each independently movable toward and away from the tubing along paths parallel to planes parallel to and intersecting the tubing axis and at an acute angle to each other. Guiding means adjacent to the downstream contacts apply welding pressure to the tubing, and further guiding means upstream of the downstream contacts but at least as close to the weld point as the upstream contacts guide the tubing as it is advanced.