Abstract: A constant voltage power supply that includes an enclosure and a transformer positioned within the enclosure. The transformer has a primary winding and first and second sets of secondary windings mounted and magnetically coupled to each other all on a single magnetic core structure. The primary winding is connected by primary circuitry to a source of electrical power. First secondary circuitry is connected to the first secondary winding set for supplying electrical power at regulated constant voltage. Second secondary circuitry is connected to the second secondary winding set for supplying auxiliary power at unregulated voltage.

Abstract: Apparatus for heating a tube/sleeve end fitting for brazing comprises an opposed pair of electrodes having arcuate electrode surfaces contoured for external peripheral engagement with a tube/sleeve end fitting, with one part of the electrode surface in engagement with the fitting sleeve and the other part of electrode surface in engagement with the tube closely adjacent to but spaced from the sleeve. A power transformer has a primary winding connected for selective application of current thereto, and a secondary winding consisting of the electrodes for selective application of heating current to an end fitting clamped between the electrodes for electrical resistance heating thereof. Timers control application of heating current to the end fitting for one or more operator-selectable predetermined timed durations.

Abstract: A method and apparatus for making camshafts of steel by hardening the lobes after they have been rough and finish machined and the final contour and finish of the cam surface formed on each lobe while the steel is soft. Each lobe with the finished cam surface thereon is disposed in an induction coil to which an alternating current is applied for not more than about five seconds to rapidly heat the peripheral portion of the lobe which is then quenched by spraying an aqueous liquid on the lobe preferably while still in the coil. This heating and quenching hardens the peripheral portion of the lobe by a martensite transformation thereof without any significant warping or distortion of the cam surface. To prevent a previously hardened lobe from being annealed by induction heating of an immediately adjacent lobe, preferably a cooling or quenching liquid is also sprayed on the camshaft between these lobes and immediately adjacent the heated lobe.

Abstract: A method and apparatus for structurally bonding together overlapped portions of sheet metal with a two-stage plastic resin between them. The resin is heated in the first stage to tack together the sheet metal portions by applying alternating current for not more than 15 seconds to an induction coil disposed adjacent one of the sheet portions to heat it to a maximum temperature in the range of 200.degree. F. to 400.degree. F. Preferably, after being tacked together, the sheet metal assembly is painted. In the second stage, the resin is fully cured to structurally bond together the sheet metal portions preferably by heating the entire assembly to a maximum temperature in the range of about 200.degree. F. to 400.degree. F. for a period of 45 to 15 minutes. Alternately, in the second stage the resin can be heated to cure and structurally bond together the sheet metal portions by at least one induction coil to which an alternating current is applied for not more than 15 seconds.

Abstract: Securing a ribbon of an expandable resin containing a heat activated blowing agent to a metal body, such as a sheet metal bow for the roof of a vehicle body, by bonding a portion of the ribbon to the body. The portion of the metal body immediately adjacent the ribbon is induction heated to transfer sufficient heat to the ribbon to bond it to the metal body without heating the bulk of the ribbon sufficiently to activate the blowing agent to expand the bulk of the ribbon into a foam resin. Subsequently, the metal body with the ribbon secured thereto is assembled with a panel and then heated to activate the blowing agent to produce a resin foam disposed between the metal body and panel.

Abstract: A plastic resin between two portions of a sheet metal assembly is heated to a curing temperature to adhere the sheet metal portions together by induction heating of only portions of the sheet metal immediately adjacent the resin. The sheet metal assembly is received between a pair of fixtures with the portions to be heated disposed between a pair of generally opposed induction coils through which an alternating current having a frequency of at least about 5,000 Hz and preferably at least 50,000 Hz is passed for less than fifteen seconds. The fixtures do not rigidly clamp the sheet metal assembly and may be opened and closed to facilitate the insertion and removal of sheet metal assemblies.