Abstract: A system and method for inductively heating and then quench hardening a portion of a workpiece, such as a several threads of a screw or bolt are disclosed. The system includes a conveyor system having a rotary conveyor for separating, aligning, and transporting each of the workpieces in aligned succession through an induction heater positioned about the rotary conveyor to heat-treat at least a portion of each of the workpieces. A sensor determines whether a workpiece is heat-treated to a minimum temperature and causes an ejector to separate heat-treated workpieces that have reached the minimum temperature from heat-treated workpieces that have failed to reach the minimum temperature. The separated workpieces are then quenched in a tank & separately removed automatically.

Abstract: A load matching circuit is disclosed for use with a frequency controlled power supply. The load matching circuit includes an input connectable to the frequency controlled power supply and an output connectable to the load, such as an induction heating coil. A load matching section is connected between the input and the output to provide enough resonance to allow the power supply to operate at or below the maximum frequency when the load is connected to the power supply and at or above the minimum frequency when the load is disconnected from the power supply. In this manner, a solid-state variable frequency power supply can continue to run even when the external load is disconnected from the power supply.

Abstract: A transverse flux heating coil is disclosed to inductively heat a continuous run of wire. In general, the transverse flux heating coil includes a single loop conductive element having a pair of termination ends extending therefrom and connectable to a power supply. The single loop conductive element is constructed to distribute the majority of the current across a width of the single loop conductive element and forms an internal heating area in which a continuous run of wire is fed therethrough. The flux generated by the current is generally transverse to a direction of travel of the wire through the heating coil. The transverse flux heating coil includes a first conductor having a width facing an internal heating area that is substantially greater than a thickness and is constructed of planar copper bar stock.

Abstract: A snubber circuit is disclosed having a pair of series connected switches, each switch having a capacitor in parallel with the switch. The snubber circuit includes a coupling element, such as a coil winding, or air-core transformer, in close proximity to a branch circuit having the capacitor therein. The coupling element is connected to a resistor and inductively couples the resistor in series with the capacitor in the branch circuit. The resistor is preferably located remotely from the capacitor. Therefore, a relatively high value, high power-rated resistor can be inductively coupled by the coupling element into the branch circuit in series with the capacitor without introducing additional inductance into the branch circuit. The invention is particularly useful in physically constricted snubber circuit arrangements and permits the use of readily available discrete resistors with the desired power rating to obtain the desired equivalent induced resistance.

Abstract: An induction heating system having at least one power supply switching network is disclosed to provide selective power control to multiple zones of an induction heating coil to achieve a desired heat distribution in a workpiece. The power supply switching network includes a number of bidirectional switches, each connected in series with one another, and each connected in parallel with a portion, or zone, of an induction heating coil. The bidirectional switches are controlled by a computer that supplies a control signal having a duty cycle as determined by the computer and a multi-zone feedback circuit. By splitting the coils and inserting a switch in parallel with each coil, and each switch in series with one another, the coil is effectively split into multiple series connected coils, thereby being more effectively controllable while avoiding physical alterations to the heating coil.