Abstract: A molten material can be heated, melted and directly solidified in a single vessel. Induction heating and melting of the molten material is achieved by magnetically coupling the field produced by current flow in a plurality of induction coils surrounding the vessel with either the molten material in the vessel, or a susceptor surrounding molten material in the vessel. Current flow is selectively removed from the plurality of induction coils, and a cooling medium surrounding the vessel, such as water flowing through hollow induction coils, solidifies the molten metal into a highly purified crystalline solid.

Abstract: A solid state switching circuit utilizes a transformer in series with the circuit's switching device by which energy initially stored in the primary of the transformer is recovered in resonant circuitry connected to the secondary of the transformer for transfer of the energy to the load when the switching device is not conducting.

Abstract: Apparatus and method are provided for damping the induced fluid flow, particularly in the region of the base plate, in an electrically conductive material that is heated and melted in a cold crucible induction furnace. Damping is accomplished by establishing a dc magnetic field such that flow of the electrically conductive liquid metal in that dc magnetic field would induce eddy currents in the liquid metal which would generate forces that tend to oppose the flow. The dc magnetic field may be established by dc current flow in the ac induction coil that induces current in the material, dc current flow in a separate dc coil, or coils, constructed to prevent excessive induced losses, by discrete magnets, or a combination of any of the three prior methods. The dc magnetic field may also be established by dc current flow in one or more dc coils disposed around a magnetic pole piece located below the base of the furnace.

Abstract: An apparatus and process are provided for detecting whether a corona discharge has occurred external or internal to equipment in which a broadband optical spectra sensor is placed. The broadband optical spectra sensor senses both the ultraviolet energy of the corona discharge and the infrared energy of afterglow of the discharge when the discharge occurs internal to the equipment. The sensed broadband optical spectra signal is processed and a determination is made as to whether the corona discharge occurred external or internal to the equipment from the pulse width of the sensed energy pulse.

Abstract: Disclosed herein is an insulating material between adjacent metal layers of a soft magnetic core, and a process for forming this insulating material. The insulating material is composed of the native metal oxides of the metallic core material.

Abstract: The exterior surface of a pipe is coated around its full perimeter without rotation of the pipe or the complete coating apparatus. In one example, the coating apparatus includes coating heads attached to a rotor with the coating material supplied under positive air pressure via a stator. The coating heads rotate with the rotor and eject coating material onto the exterior surface of the pipe. In a second example, the coating apparatus is stationary and coating material is delivered under positive air pressure though chambers within the apparatus.

Abstract: An apparatus and process are provided for multi-frequency induction heating of a workpiece. Switching devices are used to selectively add, remove or reconfigure capacitive elements in the circuit to change the circuit's resonant frequency, and consequently, the frequency of induction heating or melting power transfer from the power supply to the load.

Abstract: Disclosed herein is an insulating material between adjacent metal layers of a soft magnetic core, and a process for forming this insulating material. The insulating material is composed of the native metal oxides of the metallic core material.

Abstract: A capacitor assembly is formed from one or more capacitive elements placed between a pair of opposing brackets. Each bracket has at least one L-shaped section and an arcuate section. Each L-shaped section has a capacitor seating surface and an assembly connecting surface that is substantially perpendicular to the capacitor seating surface. The arcuate section is adjacent to the capacitor seating surface. The opposing ends of each capacitive element is in electrically contact with the capacitor seating surfaces on the opposing brackets. When secured to a bus bar by fasteners located in the regions formed by the arcuate sections of the opposing brackets the assembly connection surfaces serve as electrical and thermal conducting regions between the capacitor assembly and the bus bars. Alternatively a capacitor assembly may be secured to bus bars by fastening to the capacitor seating surfaces.

Abstract: An induction heating and melting system uses a crucible formed from a material that has a high electrical resistivity or high magnetic permeability, and one or more inductor coils formed from a wound cable consisting of multiple individually insulated copper conductors to form an induction furnace that, along with its associated power supply, provides a compact design. The system components are air-cooled; no water-cooling is required. The crucible may alternatively be shaped as a tunnel or enclosed furnace.

Abstract: A rectifier/inverter power supply for use with induction heating or melting apparatus includes a tuning capacitor connected across the output of the rectifier and input of the inverter. The tuning capacitor forms a resonant circuit with an inductive load coil at the operating frequency of the inverter. Additionally, the load coil may be formed from an active load coil connected to the output of the inverter and a passive load coil, in parallel with a resonant tuning capacitor.

Abstract: A method of sealing a foil cap to the opening of a container by induction heating is provided. A heat pipe is used to transfer heat from an induction sealing head assembly.

Abstract: Multiple workpieces are inductively heated by passing them through one or more induction heating coils. Passage of a section of each workpiece through a coil may oscillate in the forward and reverse directions, independent of the movement of the other workpieces, one or more times, to selectively heat each workpiece while operating the power supplies for each of the induction heating coils at constant current, voltage and/or power to maximize the efficiency of the electrical circuit and minimize the requirements for power supply control circuitry.

Abstract: An apparatus and process are provided for controlling the cross sectional temperature profile of a continuously moving workpiece with an induction coil assembly that provides for a combination of longitudinal and transverse magnetic flux field heating of the workpiece. The induction coil assembly includes means for laterally moving the workpiece in and out of the coil assembly without movement of the coil assembly.

Abstract: The present invention discloses a lamp comprising a lamp housing mounting an electrically driven light and a monitor circuit, the housing having power supply terminals for connection of the light to a power supply and the monitor being connected to the light such as to monitor its operation while the lamp is connected to the power supply and to provide an output indicating whether the light is functioning.

Abstract: An electric resistance high temperature vacuum furnace having radiant heating units evenly spaced around the sides and ends of the furnace hot zone. Pairs of units are automatically regulated both radially and longitudinally according to the temperature required by the workload in the hot zone. The units each comprise parallel aligned elements electrically connected in series at their one ends. Each element has lengthwise surfaces angularly disposed from each other to form a beam structure of high section modulus for stiffness and resistance to sagging. Also, the angles of the element surfaces facing a heat-reflective assembly substantially enable all of the energy radiated toward the assembly to be reflected into the hot zone in addition to the direct radiation from the surfaces facing the hot zone. The furnace includes a re-circulating cooling system for rapid cooling of the furnace and workload.

Abstract: RF energy provided by electrodes positioned between a product is used to heat a product that exhibits a variable impedance during the heating process. As the product's impedance changes during the heating process, RF heating system impedance can be maintained constant by adjusting the distance between the electrodes, adjusting the impedance of a variable impedance device connected between the RF power source and an electrode, or a combination of electrode distance adjustment and impedance adjustment of the variable impedance device. The system is particularly applicable to the heating or pasteurization of bulk food products with multiple heating zones.

Abstract: An apparatus and process are provided for reducing the electromagnetic field intensity in selected regions for a field produced when ac current flows through one or more induction coils through which a workpiece moves for induction heating of the workpiece. The electromagnetic shield has transverse screen elements through which the workpiece moves at opposing ends of the one or more induction coils. One or two longitudinal screen elements connect the transverse screen elements.

Abstract: An inductor for stationary induction heating of one or more components of a complex-shaped workpiece comprises a pair of inductor segments. The first inductor segment is connected to a high frequency ac power supply and the second inductor segment is magnetically coupled to the magnetic field created by the flow of ac current in the first inductor segment. Opposing partial openings in the first and second inductor segments form an opening in which the component can be inductively heated. The first and second inductor segments are alternatively configured in a mix of single turn, multiple single turns connected in parallel, or multiple turn coils in combination to reduce non-uniform induced cross sectional currents across the axial length of the component being inductively heat treated.

Abstract: An induction melting furnace comprises a melt chamber for heating a melt either directly by magnetic induction, or indirectly by magnetic induction heating of the melt chamber, or a combination of the two, and a meter chamber connected to the melt chamber for providing a metered discharge of the melt from the furnace. A gas can be injected into the furnace to provide a blanket over the surface of the melt in the melt chamber and a pressurized flush of the metered discharge of the melt from the meter chamber.