Abstract: A system for melting metal and holding molten metal, comprises a rectifier unit receiving AC electric power and outputting DC electric power, a plurality of inverter units, each receiving the DC electric power output by the rectifier unit and outputting AC electric power; and a plurality of induction furnaces each receiving the electric power output by a respective inverter unit. Each inverter unit comprises a plurality of inverter modules connected in parallel, each module independently being connectable to and disconnectable from the rectifier unit and the furnace. The rectifier unit comprises a plurality of rectifier modules connected in parallel, each module independently being connectable to and disconnectable from the AC supply and the inverter units.

Abstract: An apparatus for and method of pouring molten metal from a refractory vessel into the sprue of a mold where the vessel is in contact with the sprue. Molten metal is poured through the orifice of a nozzle in the bottom of the vessel. Laminar flow and velocity of the molten metal through the orifice are controlled by a stopper that extends from the orifice and also displaces molten metal in the sprue of the mold when the stopper is in the closed position to minimize excess buildup of solidified metal in the volume of the sprue. Filtering of dross can be accomplished in the refractory vessel and heating means can be provided to hold the molten metal at the appropriate temperature.

Abstract: An induction heating device for controlling the temperature distribution in an electrically conductive material, or susceptor, when heated by induced eddy currents in the material. A non-electrically conductive material can be heated in a controlled manner by placing the material near to the susceptor. Variable power is applied to multiple induction coil sections wound around the length of the susceptor from a power source by one or more switching circuits. The coil sections can be overlapped or counter-wound between adjacent coil sections, or provided power in a cascaded manner, to achieve desired temperature distributions in the susceptor. A control circuit is used to control the power applied to each coil section and the output of the power source. By placing a non-electrically conductive material near to the susceptor the material can be heated in a controlled manner.

Abstract: A vibratory conveyor assembly including a material transporting trough driven by oscillating motion which imparts a force causing materials located in the trough to be advanced. The conveyor includes a continuous, unitary saddle plate attached about the trough perpendicular to a longitudinal axis of the trough. Actuators are coupled to the saddle plate which imparts the oscillating force to the trough.

Abstract: A fault tolerant power supply circuit for a series resonant load having an inductive impedance. The power supply circuit includes alternately conducting first and second sets of switches for supplying current to the load in alternating directions. One terminal of the load is connected to a point intermediate the switches. A protective coil is connected in series with the load and the point intermediate said switches. In one embodiment of the invention, a di/dt reactor is connected in series between the switches. In that embodiment, one end of the protective coil is connected to the load and the other end of the protective coil is connected to the di/dt reactor at a point intermediate the switches.

Abstract: An induction coil for inductively heating electrically conductive materials includes a plurality of individual coil turns, each turn lying in a plane substantially perpendicular to a longitudinal axis of the coil and comprising an electrical conductor formed into an annulus. The conductor has first and second terminals for connecting the turn to an electrical circuit. The first and second terminals are adjacent each other at a preselected circumferential position on the annulus and are physically and electrically isolated from each other. The first terminal of one turn is located adjacent and electrically connected to the second terminal of an adjacent turn. The first terminal of a selected one of the plurality of turns forms a first coil terminal and the second terminal of a different selected one of the plurality of turns forms a second coil terminal.

Abstract: The present invention relates to a clamping device for increasing the heat transfer between a semiconductor device and a heat dissipating device. The clamping device comprises a clamp having a pair of cooperating jaws. A resiliently biased pressure distribution member extends from one of the jaws. The pressure distribution member and the other jaw are adapted to hold a semiconductor device in contact with the heat dissipating device. A tie rod extends between the clamp jaws. A collar is provided having a central cavity for holding the semiconductor device within and aligning the semiconductor device with respect to the heat dissipating device and the clamp. The collar also has a channel for engaging the tie rod and aligning the collar such that the semiconductor device is aligned between the pressure distribution member and the opposite clamp jaw.

Abstract: An induction furnace apparatus and method for reducing the magnetic field produced by the operation of the furnace. The induction furnace including a refractory vessel, an induction coil, and an outer shell having a layer of metallic and magnetically permeable material. The metallic and magnetically permeable material comprising a plurality of elements having a shape and size that is chosen to maximize the packing density of elements throughout the layer. The outer shell further including a top, base, and sidewall arranged about the refractory vessel such that the metallic and magnetically permeable material is formed between the refractory vessel and the outer shell. The invention provides a method for casting metallic and magnetically permeable material with or without a non-conductive matrix. The castings can be formed into inserts or incorporated into the top, base, and side wall of the outer shell.

Abstract: A hot dip coating pot for containing a coating material in a liquid state. The coating pot comprises a substantially horizontal bottom and substantially vertical side walls. The bottom and the side walls define a first interior volume for containing the coating material. The bottom wall and a lower portion of each of the side walls defines a bottom portion which is separable from an upper portion of the side walls. The bottom portion has a predetermined interior volume less than the first interior volume.

Abstract: An induction heating coil assembly for use in a roller induction heating line has a magnetic shunt for receiving a portion of an electromagnetic field generated along the axis of the induction coil and directing that portion along a path parallel to a workpiece passing along the heating line. This flux path ensures that eddy currents induced in the workpiece flow primarily perpendicular to the axis of the workpiece, and not along the axis of the workpiece where they could cause arcing between the moving workpiece and the conveyor rolls.

Abstract: An induction heating apparatus for heating continuous strip material. In a first embodiment, two coil sections each having a gap at one end for the strip material to pass edgewise into and out of the apparatus for heating wherein the coil sections are adapted for connection to two power supplies such that the first power supply connects through one half-turn of each of the coil sections, and thence to the second power supply, which is connected through the second half-turns of the respective coil sections and back to the first power supply, all in series. In a second embodiment, the coil sections are adapted for connection to four power supplies in series; each power supply connected to a respective half-turn of the coil sections, such that one half-turn is connected between each of the four power supplies. The series connection ensures uniform amplitude and phase of the electrical current applied to the induction heating coil apparatus.

Abstract: A galvanizing apparatus comprising a vessel for containing a melt of molten metal. The vessel includes at least one conical projection in its side walls around which an induction heating coil is wound to generate a uniform and continuous stirring pattern of molten metal that penetrates deeply into the pot. In a second embodiment, the galvanizing vessel has no projections from its side walls, but comprises instead one or more flat inductors disposed on the exterior wall of the vessel. The flat inductor is surrounded by magnetic return shunts for directing the magnetic force field created by the inductor.

Abstract: A video positioning system for positioning a pouring vessel over a mold sprue cup comprising one or more light fixtures for illuminating a notch on a pouring mold, an image sensor for sensing the position of the notch on the mold by producing a video notch image, a vision interface unit connected to the image sensor for converting the video notch image to digital information, and a processor connected to said vision interface unit for determining the relative position of the notch image compared to a reference position for the notch. Position correction information is sent to a position controller connected to the processor. The position controller causes the position of the pouring vessel to be adjusted by a positioning subsystem comprising a positioning driver for converting the positioning control signals to actuating signals for a positioning actuator, a positioning actuator, and at least one position sensor for sensing the position of the pouring vessel.

Abstract: An induction heating coil assembly for use in a roller induction heating line has a magnetic shunt for receiving a portion of an electromagnetic field generated along the axis of the induction coil and directing that portion along a path parallel to a workpiece passing along the heating line. This flux path ensures that eddy currents induced in the workpiece flow primarily perpendicular to the axis of the workpiece, and not along the axis of the workpiece where they could cause arcing between the moving workpiece and the conveyor rolls.

Abstract: A control system for controlling overshoot and undershoot power values when switching power from a single inverter power source to a plurality of inductive loads, or a single load having a plurality of zones, having different resonant frequencies. The control system causes a preselected amount of power to be drawn from the inverter power source and delivered to the loads, or zones in a time-shared manner. The control system varies the phase shift between load voltage and load current and selectably adjusts the amount of variation in response to overshoot and/or undershoot of power drawn from the inverter and delivered to a load or zone which can occur when switching between loads or zones.

Abstract: An induction heating coil apparatus for heating continuous strip material comprising at least a pair of generally rectangular full-turn coils arranged in parallel relation and separated from each other to permit continuous strip material to pass axially through the open interiors of the coils. Each coil has an opening in a first end portion thereof such that continuous strip material may pass into or out of the interior of the coil apparatus. The coil apparatus further comprises a pair of shunt conductors connecting the respective coils to each other. The shunt conductors are arranged on opposite sides of the openings in the end portions of the coils for providing a continuous current path from one rectangular coil to the adjacent coil. In one preferred embodiment there is an opening in the second end portion of one coil. Two more conductors, one on each side of this opening, provide connection to the respective poles of an alternating current power source.

Abstract: Electrically conductive tubing for realizing induction coils having improved efficiencies comprises an outer peripheral portion of conductive material defined by a plurality of side walls and a single hollow passageway. Each side wall has an inner and outer surface. At least one side wall has a curved outer surface. The hollow passageway is defined by the inner surfaces and can be either centered within the tubing or spaced apart from the center of the tubing. The present invention also defines an induction coil and an induction furnace having an induction coil which utilizes such tubing. The curved outer surface has a radius of curvature which is defined substantially by a function of the tubing width in the axial direction, and spacing between turns of the induction coil. The cross section of the outer surface of the outer peripheral portion of the tubing taken along a transverse axis of the tubing defines a geometric figure.

Abstract: An induction heating furnace is disclosed comprising an induction coil assembly and a ladle having a metallic shell that supports a crucible holding metal to be heated by the furnace. The ladle is readily separated from the induction coil assembly so that the heated metal may be conveniently and reliably moved among operational stations. The induction coil assembly has a preselected length which is less than the length of the shell. The induction coil assembly surrounds, but does not touch the shell and generates an electromagnetic induction field. The induction coil assembly comprises a coil, upper and lower yokes and an intermediate yoke coextensive with the coil. The upper and lower yokes are separated from each other and electromagnetically coupled together by the intermediate yoke. The upper, lower and intermediate yokes each comprise stacked laminates formed of sheets of ferrous material.

Abstract: An induction furnace is disclosed comprising a crucible for holding a material to be heated by the furnace, an induction coil assembly, and a module-support assembly surrounding and radially supporting the induction coil assembly so as to facilitate the replacement and reconnection of the induction coil assembly. The induction coil assembly comprises an induction coil, an upper yoke, a lower yoke, and a plurality of intermediate yokes that are spaced apart from each other. The induction coil is wound around the crucible and defines the periphery of the induction furnace. The intermediate yokes are arranged to extend around substantially all of the periphery defined by the wound induction coil. The upper and lower yokes are electromagnetically coupled together by the plurality of intermediate yokes.