Abstract: A compact induction heating system that is at least partially powered by a source of substantially clean DC current. The induction heating system includes a high frequency inverter with an input connected to a substantially clean DC current source, a first current conductive path including a first capacitor and a first switch closed to cause one half cycle of AC current to flow in the first path by discharging the first capacitor, a second current conductive path including a second capacitor and a second switch closed to cause a second half cycle of AC current to flow in the second path by discharging the second capacitor, a single load inductor in both of the paths with AC current flowing in a first direction through the inductor when the first switch is closed and in a second opposite direction through the inductor when the second switch is closed, and a gating circuit to alternately close the switches at a driven frequency to control heating by the load inductor.

Abstract: A compact induction heating system for use on an internal combustion engine driven implement having an engine driven alternator to generate DC current for storage in a battery used as a source of clean DC current of less than 50 volts for ignition of fuel in the engine, the system comprises a high frequency inverter with an input connected to the clean DC current source, a first current conductive path including a first capacitor and a first switch closed to cause DC current to flow in the first path and across the first capacitor, a second current conductive path including a second capacitor and a second switch closed to cause DC current to flow in the second path and across the second capacitor, a single load inductor in both of the paths with DC current flowing in a first direction through the inductor when the first switch is closed and in a second opposite direction through the inductor when the second switch is closed and a gating circuit to alternately close the switches at a driven frequency to contro

Abstract: A compact induction heating system for use on an internal combustion engine driven implement having an engine driven alternator to generate DC current for storage in a battery used as a source of clean DC current of less than 50 volts for ignition of fuel in the engine, the system comprises a high frequency inverter with an input connected to the clean DC current source, a first current conductive path including a first capacitor and a first switch closed to cause DC current to flow in the first path and across the first capacitor, a second current conductive path including a second capacitor and a second switch closed to cause DC current to flow in the second path and across the second capacitor, a single load inductor in both of the paths with DC current flowing in a first direction through the inductor when the first switch is closed and in a second opposite direction through the inductor when the current is closed and a gating circuit to alternately close the switches at a driven frequency to control heat

Abstract: A compact induction heating system that is at least partially powered by a source of substantially clean DC current. The induction heating system includes a high frequency inverter with an input connected to a substantially clean DC current source, a first current conductive path including a first capacitor and a first switch closed to cause one half cycle of AC current to flow in the first path by discharging the first capacitor, a second current conductive path including a second capacitor and a second switch closed to cause a second half cycle of AC current to flow in the second path by discharging the second capacitor, a single load inductor in both of the paths with AC current flowing in a first direction through the inductor when the first switch is closed and in a second opposite direction through the inductor when the current is closed, and a gating circuit to alternately close the switches at a driven frequency to control heating by the load inductor.

Abstract: Apparatus for inductively heating and hardening diesel cam shaft lobes includes a table supporting an inductor for radial displacement relative to the lobe of a workpiece to be hardened and a master component having a lobe identical to that of the workpiece to be hardened and supported for rotation about an axis parallel to and laterally spaced from that of the workpiece. The master component and workpiece are rotated in synchronism, and a follower roll on the table engages the lobe of the master component to accurately maintain a desired air gap between the inductor and lobe of the workpiece during the hardening operation.

Abstract: An inductor is provided for removing paint from a workpiece traveling along a longitudinal path and having a vertical stem portion intersecting the path and a hook portion having a juncture with the stem portion and extending laterally to one side of the path. The inductor has front and rear ends and the workpiece travels along the path in the direction from the front end to the rear end. The inductor comprises a coil having first and second ends for connection to a power source and a plurality of elongated conductor segments connected in series between the ends and located on opposite sides of and parallel to the path and inductively coupled with the hook and stem portions of the workpiece for heating the latter to remove the paint therefrom.

Abstract: An inductor for inductively heating bearing surfaces of a crankshaft is machined from a block of copper to provide parallel, closely spaced and integrally joined inductor block portions having machined coolant passages therein. The machined inductor is rigidly supported between juxtaposed side plates having portions of the inner surfaces thereof machined to provide recesses which receive the inductor and in which the inductor is clampingly engaged between the plates. Positioning fingers are supported by the side plates to accurately position the active face of the inductor relative to a bearing surface to be heated, and tubular leads extend upwardly between the side plates for connecting the inductor across a source of power. An inlet conduit for coolant extends laterally between the side plates, and the tubular leads provide outlets for coolant flow from the inductor.

Abstract: An inductor for inductively heating bearing surfaces of a crankshaft is machined from a block of copper to provide parallel, closely spaced and integrally joined inductor block portions having machined coolant passages therein. The machined inductor is rigidly supported between juxtaposed side plates having portions of the inner surfaces thereof machined to provide recesses which receive the inductor and in which the inductor is clampingly engaged between the plates. Positioning fingers are supported by the side plates to accurately position the active face of the inductor relative to a bearing surface to be heated, and tubular leads extend upwardly between the side plates for connecting the inductor across a source of power. An inlet conduit for coolant extends laterally between the side plates, and the tubular leads provide outlets for coolant flow from the inductor.

Abstract: A monitor device for creating a current signal having a voltage representative of the instantaneous alternating current in an induction heating coil connected to an alternating current supply by two closely spaced, parallel input conductors separated by a narrow gap or flux package through which flows the flux created by the alternating current in the parallel conductors. The monitor device comprising: a multiturn sensing winding, means for securing the winding between said parallel conductors and over the flux passage whereby the flux flowing through flux passage intersects the turns of the sensing winding, and means for creating the current signal by the induced voltage in the winding.

Abstract: A pancake-type transformer particularly suited for connection to an inductor for inductively heating crankshafts is comprised of a single turn secondary defined by a plurality of generally U-shaped tubular conductors interleaved between the turns of a tubular, multiturn primary conductor having opposite ends connectable across a source of power. The conductors of the secondary have opposite ends each interconnected with a corresponding one of a pair of terminal blocks connected to a tubular inductor. The terminal blocks are outwardly adjacent the primary and secondary conductor portions at one end of the transformer and include corresponding current collectors which extend inwardly across the opposite sides of the conductor portions at the one end of the transformer. Coolant for flow through the secondary conductors is communicated with the opposite ends thereof through coolant passageways in the current collectors.

Abstract: A method and apparatus for measuring the temperature and heating rate of a workpiece during the induction heating cycle by inducing and detecting a plurality of eddy current pulses at varying frequencies during a short power interruption to the induction coil and correlating the pulses to generate a workpiece profile which is compared to a reference profile to determine whether to reject the inductively heated workpiece.

Abstract: Process and apparatus are provided for selective heating a portion of a workpiece to achieve improved ausforming and isoforming processes when the workpiece is plastically deformed by mechanical working above the M.sub.s temperature. The process and apparatus includes a preheating step where a larger portion of the workpiece is preheated to less than the austenitic critical temperature while the final heating step conducted at a temperature higher than the austenitic critical temperature heats a smaller portion of the workpiece which is subsequently subjected to plastic deformation.

Abstract: A method and apparatus for measuring the temperature and heating rate of a workpiece during the induction heating cycle by inducing and detecting a plurality of eddy current pulses at varying frequencies during a short power interruption to the induction coil and correlating the pulses to generate a workpiece profile which is compared to a reference profile to determine whether to reject the inductively heated workpiece.

Abstract: A method for induction heating and quench hardening of helical gears provides a hardness pattern uniformly distributed to a controlled depth across and between the teeth surfaces by means of axial scanning of the workpiece and uniform quenching. Uniform quenching is achieved by directing jets of quench fluid at the workpiece toothed surface at angles horizontally offset from the radial direction.

Abstract: An induction heating apparatus and method for ultra rapid annealing of a ferromagnetic strip moving at a selected velocity along a given path. The apparatus and method uses a vacuum tube R.F. oscillator having a D.C. input power supply providing D.C. voltage and D.C. current to the oscillator, a grid, a radio frequency output, and a grid feedback circuit for driving the grid. An induction heating coil surrounds the strip, and a known length along the path. A parallel capacitor bank forms the coil into a main tank circuit with a resonant frequency. Means are provided for sensing the voltage of the induction heating coil and for adjusting said D.C. voltage of the input power supply in accordance with said sensed coil voltage to maintain the power density in the strip at a selected level as the strip passes through the coil to raise the temperature of the moving strip at a rate sufficiently high to exceed the Curie point temperature of the moving strip.

Abstract: Metal workpieces having portions of different mass are sequentially stepped through a series of induction heating units having differently contoured inductors for inductively heating the workpiece portions of different mass so as to progressively elevate the portions of different mass to a uniform temperature.

Abstract: An induction heating package sealing system includes a control which applies full power to an inductor of a first period and reduces power gradually for a second period. A seal temperature profile gradually approaching a temperature goal is thereby achieved which provides for a more uniform seal.

Abstract: Process and apparatus are provided for selective heating a portion of a workpiece to achieve improved ausforming and isoforming processes when the workpiece is plastically deformed by mechanical working above the M.sub.s temperature. The process and apparatus includes a preheating step where a larger portion of the workpiece is preheated to less than the austenitic critical temperature while the final heating step conducted at a temperature higher than the austenitic critical temperature heats a smaller portion of the workpiece which is subsequently subjected to plastic deformation.

Abstract: A method of monitoring a heating cycle of an induction heating system wherein an inductor encircles a metal workpiece and an alternating current is applied through the inductor from a power supply during the heating cycle. This method comprising the steps of generating an analog signal representative of the voltage across the inductor, as the voltage varies during the heating cycle by changes in the electromagnetic characteristics of the workpiece as the workpiece is being heated; digitizing the voltage representative analog signal; creating a trace of the digitized voltage representative analog signal, with the trace being indicative of the electromagnetic characteristic of the workpiece as sensed by the inductor voltage during the heating cycle; and, comparing the created trace with a preselected pattern.

Abstract: A method and apparatus for inductively heating in an inductor and quench hardening the finished ground cam lobes of steel camshafts to a uniform shallow pattern depth with minimal lobe surface deformation. The inductor is shaped to correspond to the contour of and encircle the individual cam lobes with a minimal uniform induction coupling gap therebetween of less than 0.1 inch, and it is energized with high intensity power at a high frequency greater than 200 KHz, with sufficient power to create a power density of at least 25 KW/inch.sup.2 at the surface of the cam lobe being heated in the inductor, for only a short heat time less than 1.0 second so as to effect the rapid inductive heating of the cam lobe surface to a uniform elevated temperature and uniform shallow depth therearound without causing unacceptable reheating and resultant drawing back or tempering of the previously hardened next adjacent cam lobe.