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 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: An induction furnace which provides a controlled escape pathway for superheated metal is disclosed. The induction furnace comprises a base layer of refractory material in the bottom of the furnace vessel. The base layer of refractory is composed of a first refractory having a maximum operational temperature and a second refractory having a maximum operational temperature lower than that of the first refractory. At least a portion of the second refractory is arranged in a contiguous zone through the thickness of the base layer. The base layer supports a packed granular refractory lining that extends up along the side wall of the vessel. In one embodiment of the invention, the base layer takes the form of a means for pushing out the packed granular lining from the furnace. The pusher means is arranged for axial movement within the furnace in response to a driving force applied from below the base layer. The pusher means contains the contiguous zone of the second refractory.

Abstract: A system for simultaneously melting metal and holding molten metal for treatment and the like comprises a plurality of separate induction furnaces, each having an induction coil. The induction coil of each furnace is arranged to inductively heat metal in its associated furnace. A plural-output power supply is operatively connected to the induction coils for supplying ac power to the coils. The power supply comprises at least one rectifier section having an output and a plurality of high-frequency inverter sections equal to the number of separate induction furnaces Each inverter section has an input operatively associated with the rectifier section output for receiving power from said at least one rectifier section and an output operatively connected to a respective one of the induction coils for supplying ac power to the induction coil. Switches are provided for selectably interrupting power from selected ones of said plurality of inverter sections to their associated induction coils.

Abstract: Induction heating vessels and methods are disclosed. One embodiment of an induction heating vessel is a bottom pouring vessel with a crucible for containing a molten metal to be heated and having an outlet in the bottom. A metallic shell with integral current limiters surrounds the crucible. A stopper is provided for selectably controlling the flow of molten metal through the outlet. A method of preheating an induction heating vessel comprises placing a susceptor inside the vessel prior to charging the vessel with material to be heated and inductively heating the susceptor by an induction coil.

Abstract: An induction melting vessel comprising a refractory crucible having an opened top end and closed bottom end, with a substantially continuous side wall. A substantially continuous metallic shell surrounds and generally conforms to the side wall and extends for at least a majority of the height of the side wall from the bottom end to the top end. The shell has a bottom end corresponding to the bottom end of the crucible and a top end corresponding to the top end of the crucible. A portion the shell adjacent the top end thereof and a portion of the shell adjacent the bottom end thereof have discrete physically integral but electrically isolated regions therein for limiting the flow of electric current in the shell. In one embodiment of the invention, the regions are defined by a plurality of slits through the shell and extending from the top and bottom ends thereof toward the respective opposite ends. The slits have a length not exceeding have the distance to the respective opposite end.

Abstract: A coreless induction furnace comprising a crucible for holding a quantity of metal to be heated by the furnace. The crucible has an open top, side walls and a closed bottom. An induction coil is operatively associated with the crucible for generating a time-varying magnetic induction field. Coupling structure extending above the top of the crucible is provided to couple at least a portion of the induction field to the center portion of the top surface of the metal to be heated.

Abstract: An apparatus and method for inductively melting a quantity of metal, without having to contain the metal in a crucible, is described. The solid metal to be melted is placed within a first induction coil excited by an alternating current and adapted to provide a greater electromagnetic force towards the lower portion of the quantity of metal. The solid metal rests on a support, having an opening therethrough, which also comprises means for keeping the support at a low temperature relative to the metal as it melts. When energy in the form of the alternating current is provided to the coil, the metal melts from the top downward, but the concentration of electro-magnetic force towards the bottom of the metal causes the liquid metal to retain a cylindrical shape. A non-varying electromagentic field is applied to the quantity of metal to minimize violent stirring of the molten portion of the quantity of metal caused by the time-varying field.

Abstract: A method of refining steel utilizing induction melting furnaces sized for use in micro mills consists of charging a medium frequency induction melting furnace having a maximum production rate of about 50 tons per hour with pre-refined steel, and melting steel in the furnace. The melted steel is transferred to a refining vessel, the refining vessel has a high free board, induction heating and stirring capacity and apparatus for supplying blasts of gas. The refined steel is then transferred to a tundish for a continuous casting operation.

Abstract: Apparatus and method for providing a constant level of molten metal to a mold in gas permeable shell mold casting. The apparatus includes a furnace for melting and Holding metal to be cast. Structure is provided for locating a mold to be filled in casting relationship with the molten metal in the furnace and for causing molten metal to be drawn from the furnace into the mold. Structure responsive to the sensor is provided for tilting the furnace relative to the mold causing the level of the molten metal to remain constant relative to the mold as the mold is being filled.

Abstract: A packaging system for an induction furnace has an equipment housing within which is located all the operating equipment for the furnace. The equipment is centrally located within the housing and is reached by access panels in the housing cover, which forms a deck. The operating equipment is fully enclosed and protected by the housing, yet can be easily reached by means of the access panels for maintenance, troubleshooting and the like.

Abstract: Apparatus and method for providing a constant level of molten metal to a mold in gas permeable shell mold casting. The apparatus includes a furnace for melting and holding metal to be cast. Structure is provided for locating a mold to be filled in casting relationship with the molten metal in the furnace and for causing molten metal to be drawn from the furnace into the mold. Structure responsive to the sensor is provided for tilting the furnace relative to the mold causing the level of the molten metal to remain constant relative to the mold as the mold is being filled.

Abstract: A packaging system for an induction furnace has an equipment housing within which is located all the operating equipment for the furnace. The equipment is centrally located within the housing and is reached from either side by access panels in the housing cover, which forms a deck. The operating equipment is fully enclosed and protected by the housing, yet can be easily reached by means of the access panels for maintenance, trouble shooting and the like.

Abstract: A levitation heating system uses only a single power supply for both levitation and heating, but permits the frequency of the power supply to be changed to control heating effects independently of levitation forces. The levitation force is kept constant by changing the apparent impedance of the induction and levitation coil as the frequency is changed, thereby providing a constant applied current to the coil over a range of applied frequencies. Feedback is employed to assure constant current in the coil.

Abstract: A plurality of zones of an induction heating coil are individually controlled by varying the current through one or more zones of the coil to obtain a desired temperature profile in a workpiece. The current flow through a zone of the coil is determined by the conduction state of an associated saturable reactor, which is controlled in accordance with a preselected value or a variable value generated, for example, by a computer.