Abstract: An apparatus and process are provided for regulating the voltage across a resistive or inductive load by phase angle control of the applied load voltage. Instantaneous load voltage is compared with a preset reference value to control the phase angle of the applied load voltage by means of rms voltage approximation feedback control. A visual display can be provided to assist the user in establishing the preset reference value.

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: An electrical power management system is provided for effectively managing available electrical power for recharging batteries used in a plurality of battery-powered computers. The electrical power management system is of particular value when current from the available power supply is limited relative to the total charging current required for the batteries. Charging currents can be sensed to better manage the recharging process. Charging data can be sensed and recorded to optimize battery charging for a plurality of battery-powered computers.

Abstract: An apparatus and process are provided for induction heat treatment of electrically conductive workpieces. The inductor assembly is formed from a single piece inductor that utilizes an electrically non-conductive top, side and bottom frames to hold flux concentrators in place over the sides of the inductor. Flux concentrators can be changed by unfastening the frame members, removing the existing flux concentrators, inserting new flux concentrators, and fastening the frame members. One or more of the frame members may serve as a receiving chamber for supply of a quench medium to an induction heated workpiece positioned in an opening in the inductor.

Abstract: A clamping device for an injection blow molding machine incorporates separate clamp movement actuators for joining or separating opposing mold parts and clamping actuators for applying a clamping force to closed mold parts. Opposing locking columns and locking collars are locked together and a clamping force is applied to opposing locked columns and collars. A stroke movement of the locking collars can optionally be provided to allow maximum clamp area clearance for a preform or blow-molded product entering or leaving the clamp area. The distance of stroke movement can be adjusted to accommodate molds of varying sizes.

Abstract: An induction foil cap sealer includes a sealing head module and power supply module that can be separately mounted and replaced. Both modules are convection air-cooled without a requirement for forced air-cooling or water cooling.

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: An induction furnace is provided with a bottom induction coil to melt, heat and/or stir an electrically conductive material placed in the furnace. The furnace is particularly useful for electrically conductive materials having a relatively low value of thermal conductivity, such as aluminum or an aluminum alloy.

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 plurality of billets are inductively heated in a staged process wherein the output current of a power supply is repeatedly time shared among a plurality of induction coils within which the plurality of billets have been placed. The time periods of the applied current to each coil become sequentially shorter over the total heating time of a billet to allow magnetically induced heat to conduct to the center of the billet during the dwell periods between applied electrical current periods. This maximizes the efficiency of the output of the power supply while melting of the outer regions of a billet is avoided in a process wherein the billets do not have to be moved during the overall billet total heating time.

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.

Abstract: Apparatus for pouring of molten metal from a vessel onto the gating system of a mold includes a shield assembly that diverts any abnormal flow of molten metal occurring between normal flow of molten metal onto the gating system when molds are indexed for pouring. The shield assembly protects sensitive components of the mold, such as the gating and casting patterns in a lost foam casting process, from abnormal flow of molten metal.

Abstract: A transverse flux induction heating apparatus adjusts the level of edge heating of a workpiece by changing the pole pitch of induction coils forming the apparatus to provide a more uniform transverse temperature of the workpiece. Changes in the operating frequency of the induction power supply and in the distance between induction coils and workpiece are not required to adjust edge frequency heating. The pole pitch, and therefore, the level of edge heating can be continuously changed, or conveniently adjusted prior to a production run, in a high speed continuous heat treatment process for a workpiece.

Abstract: A fault current tolerant power supply circuit having a dc power source and switching devices for inverting dc current from the source into ac load current includes a protective circuit for protecting the switching devices from overvoltage conditions when an inductive load is short-circuited. The protective circuit uses a capacitive component to absorb charge during a short circuit to protect non-conducting switching devices from an overvoltage condition.

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 furnace system has an active induction coil surrounding a crucible. A passive induction coil also surrounds the crucible. The passive induction coil is connected in parallel with a capacitor to form an L-C tank circuit. A source of ac current is provided to the active induction coil to produce a magnetic field that inductively heats and melts an electrically conductive material in the crucible. The magnetic field also magnetically couples with the passive induction coil to induce a current in the passive induction coil. This induced current generates a magnetic field that inductively heats and melts the material. The resistance of the L-C tank circuit is reflected back into the circuit of the active induction coil to improve the overall efficiency of the induction furnace system. The crucible may be open-ended to allow the passage of the electrically conductive material through the crucible during the heating process.

Abstract: A compact magnetic field exposure sensor and analysis system suitable for use in the calibration of induction heating processes such as foil cap sealing or the heat treatment of metals. The compact sensor is a self-contained sensing coil, and signal storage, processing and/or transmittingcomponents that can be configured to suit narrow-mouth containers. Detected and/or processed signals can be transmitted to remote storage, processing and/or display subsystems from the sensor.

Abstract: An oven temperature control circuit utilizes one or more light emitting diodes to establish a clamping voltage that limits the voltage at the input of a circuit component, such as an analog-to-digital converter, when a sensor, such as a thermistor, is connected to the input of the circuit component and the sensor is subjected to an EMI pulse. A method is provided for continued execution of a heating process after an unavoidable and unintentional interruption.

Abstract: An induction 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 induction melting system is particularly useful for separating metal from scrap, casting molds directly from the induction furnace, and providing a continuous supply of molten metal.

Abstract: A flat inductor heating system for inducing heat in a variety of applications including heating, melting and holding a melt at temperature. The system may also be used to stir the melt. The system includes at least one flat induction coil cast in an aggregate of shot and a binding material. The aggregate serves to direct magnetic flux to the melt, thereby improving efficiency. The system is situated above a refractory holding the melt and may either rest on the refractory or be raised and lowered into and out of the refractory.