Abstract: An electromagnetic induction melting furnace to control an average nominal diameter of the TiB2 cluster of the Al—Ti—B alloy includes a main body containing the melted alloy; and a multi-layer coil disposed on the main body, wherein a frequency of the alternative current of each coil of the multi-layer coil is different, and the alloy is heated by inducing a magnetic field generated by the alternative currents. The selection of the frequency and the changeable magnetic field may reduce the cohesion force between the TiB2 grains of the Al—Ti—B alloy to control the average nominal diameter of the TiB2 cluster.

Abstract: An electromagnetic induction melting furnace to control an average nominal diameter of the TiC cluster of the Al—Ti—C alloy includes a main body containing the melted alloy; and a multi-layer coil disposed on the main body, wherein a frequency of the alternative current of each coil of the multi-layer coil is different, and the alloy is heated by inducing a magnetic field generated by the alternative currents. The selection of the frequency and the changeable magnetic field may reduce the cohesion force between the TiC grains of the Al—Ti—C alloy to control the average nominal diameter of the TiC cluster.

Abstract: Apparatus and process for heating and melting a material in a susceptor vessel are provided wherein phase synchronized ac voltage is supplied from a separate power source to each one of at least two induction coils in separate zones around the vessel. Power magnitude from each source to an induction coil is controlled by pulse width control of the source's output voltage. Output frequency from each source is either fixed or variable based upon the electrically conductive state of the material. Optional electromagnetic stirring is achieved by establishing a phase shift between the voltage outputs of the power supplies after the material in the susceptor vessel has melted.

Abstract: Apparatus and method are provided for electric induction heating and melting of a transition material that is non-electrically conductive in the solid state and electrically conductive in the non-solid state in an electric induction heating and melting process wherein solid or semi-solid charge is periodically added to a heel of molten transition material initially placed in a refractory crucible. Induction power is sequentially supplied to a plurality of coils surrounding the exterior height of the crucible at high power level and high frequency with in-phase voltage until a crucible batch of transition material is in the crucible when the induction power is reduced in power level and frequency with voltage phase shifting to the induction coils along the height of the crucible to induce a unidirectional electromagnetic stir of the crucible batch of material.

Abstract: Apparatus and method are provided for electric induction heating and melting of a transition material that is non-electrically conductive in the solid state and electrically conductive in the non-solid state in an electric induction heating and melting process wherein solid or semi-solid charge is periodically added to a heel of molten transition material initially placed in a refractory crucible. Induction power is sequentially supplied to a plurality of coils surrounding the exterior height of the crucible at high power level and high frequency with in-phase voltage until a crucible batch of transition material is in the crucible when the induction power is reduced in power level and frequency with voltage phase shifting to the induction coils along the height of the crucible to induce a unidirectional electromagnetic stir of the crucible batch of material.

Abstract: Apparatus and method are provided for electric induction heating and melting of a transition material that is non-electrically conductive in the solid state and electrically conductive in the non-solid state in an electric induction heating and melting process wherein solid or semi-solid charge is periodically added to a heel of molten transition material initially placed in a refractory crucible. Induction power is sequentially supplied to a plurality of coils surrounding the exterior height of the crucible at high power level and high frequency with in-phase voltage until a crucible batch of transition material is in the crucible when the induction power is reduced in power level and frequency with voltage phase shifting to the induction coils along the height of the crucible to induce a unidirectional electromagnetic stir of the crucible batch of material.

Abstract: Apparatus and method are provided for electric induction heating and melting of a transition material that is non-electrically conductive in the solid state and electrically conductive in the non-solid state in an electric induction heating and melting process wherein solid or semi-solid charge is periodically added to a heel of molten transition material initially placed in a refractory crucible. Induction power is sequentially supplied to a plurality of coils surrounding the exterior height of the crucible at high power level and high frequency with in-phase voltage until a crucible batch of transition material is in the crucible when the induction power is reduced in power level and frequency with voltage phase shifting to the induction coils along the height of the crucible to induce a unidirectional electromagnetic stir of the crucible batch of material.

Abstract: Electromagnetic device for fusion and interfacial agitation of diphase systems, particularly for the acceleration of metallurgic or pyrochemical processes, which includes for example a crucible to contain a diphase system, an inductor surrounding this crucible, and a circuit for the supply of the inductor by a current with two components, namely a high frequency component which melts the phases of the system and a low frequency component which agitates the interface of the phases.

Abstract: Apparatus and method are provided for electric induction heating and melting of a transition material that is non-electrically conductive in the solid state and electrically conductive in the non-solid state in an electric induction heating and melting process wherein solid or semi-solid charge is periodically added to a heel of molten transition material initially placed in a refractory crucible. Induction power is sequentially supplied to a plurality of coils surrounding the exterior height of the crucible at high power level and high frequency with in-phase voltage until a crucible batch of transition material is in the crucible when the induction power is reduced in power level and frequency with voltage phase shifting to the induction coils along the height of the crucible to induce a unidirectional electromagnetic stir of the crucible batch of material.

Abstract: Disclosed is a hybrid multi-user interference cancellation method for canceling interference between a plurality of user signals, which comprises: receiving a plurality of external user signals, calculating powers of the user signals, and numbering the calculated signal powers in their intensity orders; sorting the user numbers in descending order; forming at least one user cluster so that the signal powers following the sorted user numbers may differ less from a central value or a mean value in the same cluster; and performing parallel interference cancellation on the respective user signals within the same cluster, and performing successive interference cancellation between the formed clusters.

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: An induction heating apparatus includes a measurement device for indicating an electrical resistance of a material to be heated. A controller is configured for energizing an inductor in response to the indicated resistance. An inductor may be energized with an alternating current, a characteristic of which may be selected in response to an indicated electrical resistance. Alternatively, a temperature of the material may be indicated via measuring the electrical resistance thereof and a characteristic of an alternating current for energizing the inductor may be selected in response to the temperature. Energizing the inductor may minimize the difference between a desired and indicated resistance or the difference between a desired and indicated temperature. A method of determining a temperature of at least one region of at least one material to be induction heated includes correlating a measured electrical resistance thereof to an average temperature thereof.

Abstract: Molten metal, or other electrically conductive material, in a vessel can be inductively heated, and simultaneously inductively stirred. A single-phase ac supply provides induction heating power to at least one set of three induction coil sections surrounding the vessel. A three-phase ac supply provides induction stirring power to at least one set of three induction coil sections surrounding the vessel. The single-phase ac supply is capacitively connected to the coil sections to form a heat resonance circuit, and the three-phase ac supply is inductively connected to the coil sections to form a stir resonance circuit. The heat circuit capacitive elements provide a sufficient impedance to the output of the three-phase ac supply to block power transfer from its output to the input of the single-phase supply. The stir circuit inductive elements provide a sufficient impedance to the output of the single-phase supply to block power transfer from its output to the input of the three-phase supply.

Abstract: Molten metal, or other electrically conductive material, in a vessel can be inductively heated, and simultaneously inductively stirred. A single-phase ac supply provides induction heating power to at least one set of three induction coil sections surrounding the vessel. A three-phase ac supply provides induction stirring power to at least one set of three induction coil sections surrounding the vessel. The single-phase ac supply is capacitively connected to the coil sections to form a heat resonance circuit, and the three-phase ac supply is inductively connected to the coil sections to forma a stir resonance circuit. The heat circuit capacitive elements provide a sufficient impedance to the output of the three-phase ac supply to block power transfer from its output to the input of the single-phase supply. The stir circuit inductive elements provide a sufficient impedance to the output of the single-phase supply to block power transfer from its output to the input of the three-phase supply.

Abstract: Molten metal, or other electrically conductive material, in a vessel can be inductively heated, and simultaneously inductively stirred. A single-phase ac supply provides induction heating power to at least one set of three induction coil sections surrounding the vessel. A three-phase ac supply provides induction stirring power to at least one set of three induction coil sections surrounding the vessel. The single-phase ac supply is capacitively connected to the coil sections to form a heat resonance circuit, and the three-phase ac supply is inductively connected to the coil sections to forma a stir resonance circuit. The heat circuit capacitive elements provide a sufficient impedance to the output of the three-phase ac supply to block power transfer from its output to the input of the single-phase supply. The stir circuit inductive elements provide a sufficient impedance to the output of the single-phase supply to block power transfer from its output to the input of the three-phase supply.

Abstract: An induction heating furnace includes a furnace body having a side wall extending so obliquely as to increase in radius from the bottom to the top edge portion and formed by a plurality of longitudinally split, conductive segments arrayed circumferentially and insulated from each other, a first induction heating coil arranged at an outer periphery of the side wall for subjecting a to-be-heated material accommodated in the furnace body to induction heating and a melt-use power source for supplying AC power to the first induction heating coil.

Abstract: An induction heating furnace includes a furnace body having a side wall extending so obliquely as to increase in radius from the bottom to the top edge portion and formed by a plurality of longitudinally split, conductive segments arrayed circumferentially and insulated from each other, a first induction heating coil arranged at an outer periphery of the side wall for subjecting a to-be-heated material accommodated in the furnace body to induction heating and a melt-use power source for supplying AC power to the first induction heating coil.

Abstract: A high-frequency device for melting and refining inorganic compounds having a high-frequency oscillation system and a crucible. The high-frequency system includes an induction coil looping around the crucible and at least two oscillator circuits connectable in parallel to the induction coil and providing redundant high frequency energy. Each self-exciting oscillator includes one of the capacitors and the induction coil. The device may further include a power supply, a control cabinet having operating units, and a process control system.

Abstract: An alloying system for a galvanized steel sheet, the alloying system using an induction heating coil, wherein an impedance matching apparatus is provided between the induction heating coil and a high frequency power source. The impedance matching apparatus comprises a matching transformer having a plurality of intermediate contact points for arbitrarily selecting a turn ratio, and a switching device for alternative changeover of the intermediate contact point, whereby even when the load impedance of the steel sheet varies, maximum power source output is obtained, such that an appropriate heating temperature necessary for forming an alloy layer of the steel sheet can be supplied.

Abstract: An induction furnace having a voltage source series inverter, a load circuit having a combination of an induction coil and a resonating capacitor bank, and control circuitry to phase lock the inverter frequency to the natural resonant frequency of the load. The capacitor bank can be divided into two groups, one across the output of the inverter and the other in series with the load. This arrangement allows for the division of the inverter voltage across the furnace coil according to the ratio of the two capacitances. The inverter uses pulse width modulation and is buffered from the load circuit by means of a small series connected inductor. Additionally, the system can have a common power supply system that supplies power in any desired proportion to a plurality of induction furnaces.

Abstract: A coreless induction furnace includes a vertical melting crucible defining a melting chamber having upper and lower chamber portions and at least two coils. A first one of the coils is disposed so as to surround the upper chamber portion and a second one of said coils is disposed so as to surround the lower chamber portion. The furnace also includes a single-phase load-commutated oscillation circuit converter, a plurality of capacitors and an electrical circuit system electrically connecting the coils, the capacitors and the converter. The electrical interconnection is such that the first one of the coils is electrically connected in series with a first one of the capacitors having a first capacitvie impedance to thereby present a first oscillation circuit, and the second one of the coils is electrically connected in series with a second one of the capacitors having a second capacitive impedance to thereby present a second oscillation circuit.

Abstract: In a process for the operation of coreless induction melting and/or holding furnaces--in which there results in the melting operation at a relatively high induction frequency (as compared to the mains frequency) a slight stirring motion in the melt, but a high degree of effectiveness for the melting process, and in the melting and holding operation at a correspondingly lower induction frequency there results a greater stirring motion in the melt, but a lower degree of effectiveness for the melting process--it is provided that at least one capacitor switched in parallel to the induction coil(s) is provided, which capacitor(s), together with the induction coil(s), form a resonant circuit; and that in the transition from the melting operation with slight stirring motion in the melt to the melting or holding operation with greater stirring motion, or in the reverse transition, the capacitor capacitance and/or the inductance present in the resonant circuit is increased, or as the case may be, decreased.

Abstract: A high-frequency induction heater having a working coil for providing a high-frequency application of power to a sample is provided with a control circuit for controlling the amount of power to the working coil. A phase control member can be triggered to provide a first level of power to the sample to heat it below its combustion level, to thereby remove any exterior stains. Subsequently, a second level of power can be applied for a predetermined period of time to heat it to a combustion point whereby the combustion gases of the sample are free from any byproducts of the stain and an accurate measurement can be accomplished.

Abstract: In an electric furnace including a heating device which includes a cooling water passage for cooling the heating device to prevent the heating device from melting, estimation of a molten metal temperature in the electric furnace using a heat equilibrium model is conducted taking into account a thermal loss by the cooling water, i.e., the amount of a heat taken away by the cooling water. Further, the amount of the cooling water flowing through the heating device is adjusted so that the thermal loss by the cooling water is in a predetermined optimum thermal loss range.

Abstract: Temperature sensors are embedded in a refractory material that make up the walls of a body of an induction furnace and detect an increase in the temperature of a molten metal in the body of the furnace due to the bridging of a metal material that is to be melted in the furnace body. The temperature sensors are connected to an antenna for detecting runout. Since various electrical data (voltage, current, power, frequency, etc.) that affect an alternating current to be supplied to a coil of the induction furnace change depending on the temperature of the molten metal, bridging of the metal material is detected by determining the rates of temporal change in these electrical data. Furthermore, the changes in the electrical data with respect to the progress of the operation of the induction furnace are previously stored in data storage, and the electrical data stored are compared with electrical data detected in the induction furnace in operation.

Abstract: In a method for open-loop/closed-loop control of current converter valves of at least two load-guided parallel oscillating circuit inverters being supplied from a common direct current or direct voltage source and being connected in series on the DC side, each inverter has one induction furnace with a compensating conductor. Two diagonally opposed current converter valves are ignited at a time in one inverter to establish a flow of current from the source with a series-connected choke through the parallel oscillating circuit connected to that inverter. Load phase angles of the parallel oscillating circuit inverters are adjusted, resulting in arbitrarily specified individual powers of the parallel oscillating circuits wherein a maximum power that can be output by the source is taken into account, and attaining a specified ratio between the individual powers of the parallel oscillating circuits.

Abstract: Temperature sensors are embedded in a refractory material that make up the walls of a body of an induction furnace and detect an increase in the temperature of a molten metal in the body of the furnace due to the bridging of a metal material that is to be melted in the furnace body. The temperature sensors are connected to an antenna for detecting runout. Since various electrical data ( voltage, current, power, frequency, etc.) that affect an alternating current to be supplied to a coil of the induction furnace change depending on the temperature of the molten metal, bridging of the metal material is detected by determining the rates of temporal change in these electrical data. Furthermore, the changes in the electrical data with respect to the progress of the operation of the induction furnace are previously stored in data storage, and the electrical data stored are compared with electrical data detected in the induction furnace in operation.

Abstract: Apparatus to float and melt particularly small pieces of high-melting point metal continuously while making the amount of meltable liquid metal greater than the capacity of a crucible. A conductive crucible having segments includes an upper cylindrical crucible portion and a lower closed-end crucible portion. An induction coil is arranged outside the upper crucible portion, whereas an induction coil is arranged below the induction coil. The lower crucible portion is in contact with the upper crucible portion and located on the inside of the induction coil at the initial melting stage. The lower crucible portion is lowered as a columnar metal grows and solidifies between molten metal and the lower crucible portion. A continuous feeder continuously feeds cold material. A molten metal surface thermometer and a molten metal surface level gauge are arranged above the crucible. The operation of the continuous feeder is regulated within a desired range of values of the molten metal surface thermometer.

Abstract: In a system of supplying electric power to an induction furnace, a required heating power is directly supplied to the induction furnace from an ac synchronous generator driven by a prime mover, such as a diesel engine, via a single-phase coil. At the same time, the voltage to be supplied to the single-phase coil is rendered continuously variable by an automatic voltage regulator of the generator to render continuously variable the heating power corresponding to the voltage to be supplied, and the frequency of the voltage to be supplied is rendered continuously variable by an automatic frequency regulator of the prime mover in accordance with predetermined mutual relationships with the voltage to be supplied. In addition, at the start of power supply, the voltage to be supplied and the frequency thereof are increased with gradients for a predetermined time duration from their predetermined minimum values to their rated values in accordance with the predetermined mutual relationships.

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: In one embodiment, an induction furnace is disclosed having a crucible, first and second set of induction coils surrounding the crucible and master and slave inverters, whereas in another embodiment, related to a channel-type induction furnace, the lower portion of the crucible houses at least first and second induction coils. The master and slave inverters each have a switching device with known turn-off-time characteristics for generating an alternating polarity output voltage across a load. The master inverter monitors the current, detects the zero-crossing of the current in the first induction coils, and generates a control signal in response to such detection of zero-crossing. The control signal is generated at an interval following the detection of the zero-crossing which is greater than the turn-off-time characteristic of the switching device.

Abstract: An induction melting apparatus including a vessel for holding a melt of molten metal, an induction coil operatively associated with the vessel, and a power supply for providing power input to the induction coil. The power input has a melting component at a first preselected frequency for operatively holding the melt at a preselected temperature by induction heating and an agitation component at a second preselected and different frequency for agitation of the melt by inducing turbulence therein. The power supply comprises an agitation power supply circuit operatively supplying current to the coil at the second frequency, and a melting power supply circuit including a series resonant circuit through which the melting component is operatively applied to the coil at the first frequency at the same time as the agitation component is applied to the coil.

Abstract: A method of continuously melting a material comprises the steps of depositing carbon in a crucible furnace provided with a melt outlet and an inlet in an upper portion thereof, heating the carbon by electromagnetic induction heating by an electromagnetic coil provided around the outer periphery of the furnace, continuously supplying the material to be melted onto the heated carbon through the inlet and melting the material to be melted by electromagnetic induction heating so as to cause a melt to continuously flow out of the furnace through the melt outlet. The temperature of the melt flowing out of the furnace is adjusted by controlling the ratio between the quantities of heat supplied by the electromagnetic induction heating to the carbon and to the material to be melted.

Abstract: A control circuit particularly useful for controlling the application of power to a single phase induction furnace from a normal line frequency power supply is provided. The load has a large inductance and a resistance. A switch, preferably formed from thyristors, is provided in series connection with the furnace load. A first capacitor is provided in parallel connection with the series connected switch and load. A second capacitor is provided in series connection with the series connected switch and load and the first capacitor whereby selective operation of conduction of the switch results in the smooth and continuous control of furnace power. In an alternative embodiment small inductors are placed in series with the capacitors to provide a filter preferably tuned to the fourth harmonic of the power supply.

Abstract: An apparatus for growing a GaAs single crystal by relying on the floating zone technique in a cylinder charged with a GaAs polycrystal and a GaAs single seed crystal, comprising an As container communicating with the interior of the cylinder to supply an optimum vapor pressure of As into the cylinder under the condition that a continuous temperature variation is established between this As container and the GaAs crystals charged in the cylinder, whereby a GaAs single crystal having little deviation from stoichiometry and having a good crystal perfection is obtained.

Abstract: At least one arc furnace and at least one induction furnace are connected to the same AC network, the induction furnace being connected via a controllable alternating voltage converter so as to permit compensation of active power fluctuations in the network caused by operation of the arc furnace and the induction furnace being designed to contain scrap for its inductive preheating before charging in the arc furnace.

Abstract: Apparatus for controlling furnace temperature particularly in an annealing furnace used for annealing elongated product, such as pipe and tubing, on a continuous basis. The apparatus includes a pyrometer used to produce an electrical signal proportional to the temperature of the workpiece immediately after heating by an induction coil in the furnace, means for comparing this electrical signal to a set point signal proportional to the desired temperature of the workpiece and if these signals differ a control signal is produced to either increase or decrease the power input to the induction coil to correspondingly increase or decrease the temperature of the workpiece to the desired temperature.