Abstract: An induction heating device is provided. The induction heating device comprises a plurality of induction heating devices disposed at intervals along the circumference of a ring-shaped workpiece, a setting unit for setting induction heating conditions, and a switching control unit. Each of the plurality of induction heating devices comprises heating coils disposed facing areas to be heated of the workpiece, a plurality of transformers connected to the heating coils in parallel, a plurality of matching units connected to any one of the plurality of transformers, an inverter unit having a rectifier unit and an inverter unit, an inverter control unit having a rectification control unit, and a group of switches.

Abstract: An induction heating device is provided. The induction heating device comprises a plurality of induction heating devices disposed at intervals along the circumference of a ring-shaped workpiece, a setting unit for setting induction heating conditions, and a switching control unit. Each of the plurality of induction heating devices comprises heating coils disposed facing areas to be heated of the workpiece, a plurality of transformers connected to the heating coils in parallel, a plurality of matching units connected to any one of the plurality of transformers, an inverter unit having a rectifier unit and an inverter unit, an inverter control unit having a rectification control unit, and a group of switches.

Abstract: A load abnormality detecting circuit for an inverter to detect abnormality of a load during an operation of the inverter which has a self-arc-extinguishing element as a switching element and a phase synchronizing loop controlling an output frequency to be a resonance frequency of the load, the load abnormality detecting circuit includes a phase shift detection part that detects a phase shift between a gate voltage signal controlling ON/OFF of the self-arc-extinguishing element and an output current of the inverter which is applied to the load, and that sends a first abnormal load signal based on the phase shift.

Abstract: A method for setting conditions for a shaft diameter enlargement, a shaft diameter enlargement method, and a shaft diameter enlargement apparatus are provided. A controller of the shaft diameter enlargement apparatus controls a compressing section, a bending section, and a rotating section to enlarge an intermediate portion of a shaft workpiece to have a predetermined outer diameter by rotating the shaft workpiece about its axis with axial compressive force a bending angle being applied to the intermediate portion. The controller determines whether the shaft workpiece is acceptable, based on the number of rotations of die shaft workpiece required for enlarging the intermediate portion to have the predetermined outer diameter or based on an enlargement ratio of the intermediate portion.

Abstract: A load abnormality detecting circuit for an inverter to detect abnormality of a load during an operation of the inverter which has a switching element and a phase synchronizing loop controlling an output frequency to be a resonance frequency of the load, the load abnormality detecting circuit includes a phase shift detection part that detects a phase shift between an output voltage and an output current which are applied from the inverter to the load and sends an abnormal load signal based on the detected phase shift. The switching element including a self-arc-extinguishing element and a reflux diode connected in reversely parallel to the self-arc-extinguishing element. The phase shift detection part detects advance and delay of a phase of the output current with respect to the output voltage.

Abstract: A power supply device includes a first output unit that outputs a first alternating current, a second output unit that outputs a second alternating current, and a current combining unit that combines the first alternating current and the second alternating current. The current combining unit includes a first bus bar, a second bus bar, a first conductive member welded to a first surface of the first bus bar and connected to the first output unit, a second conductive member that is welded to a second surface of the first bus bar, penetrates the second bus bar, and is connected to the second output unit, a third conductive member welded to a first surface of the second bus bar and connected to the second output unit, and a fourth conductive member that is welded to a second surface of the second bus bar, penetrates the first bus bar, and is connected to the first output unit. The second surface of the first bus bar faces the second surface of the second bus bar.

Abstract: A power conversion apparatus includes a rectifier to convert AC power into constant-current DC power, a resonant inverter to convert the DC power into AC power to be output to a load, and a control unit to receive settings of an output current value of the inverter, a current-supplying time of the inverter, an operation rate defined by dividing the current-supplying time by a sum of the current-supplying time and a non-current-supplying time, and a resonance frequency of the load. The control unit operates the rectifier and the inverter only when it determines that it is operable to perform an output in accordance with the set conditions, based on data in which the output frequency, the current-supplying time and the operation rate are associated with an allowable output current value of the inverter at a temperature equal to or lower than a maximum operable temperature of a switching device.

Abstract: A power conversion apparatus includes a rectifier to convert AC power into constant-current DC power, a resonant inverter to convert the DC power into AC power to be output to a load, and a control unit to receive settings of an output current value of the inverter, a current-supplying time of the inverter, an operation rate defined by dividing the current-supplying time by a sum of the current-supplying time and a non-current-supplying time, and a resonance frequency of the load. The control unit operates the rectifier and the inverter only when it determines that it is operable to perform an output in accordance with the set conditions, based on data in which the output frequency, the current-supplying time and the operation rate are associated with an allowable output current value of the inverter at a temperature equal to or lower than a maximum operable temperature of a switching device.

Abstract: A heating apparatus and a heating method are provided. The heating apparatus includes a coil configured to receive AC power to form a magnetic field that inductively heats a workpiece, a spray unit configured to spray cooling fluid including a liquid to the coil in a form of mist at least during a period in which the AC power is supplied to the coil. Alternatively, the spray unit may be configured to spray the cooling fluid in the form of mist to a heating target portion of the workpiece placed in the magnetic field at least during the period in which the AC power is supplied to the coil.

Abstract: A heating apparatus and a heating method are provided. The heating apparatus includes a coil configured to receive AC power to form a magnetic field that inductively heats a workpiece, a spray unit configured to spray cooling fluid including a liquid to the coil in a form of mist at least during a period in which the AC power is supplied to the coil. Alternatively, the spray unit may be configured to spray the cooling fluid in the form of mist to a heating target portion of the workpiece placed in the magnetic field at least during the period in which the AC power is supplied to the coil.

Abstract: A method for manufacturing a rack bar having a first rack and a second rack is provided. The first and second racks have an angular positional difference around an axis of the rack bar. The method includes forming a first flat surface and a second flat surface on an outer circumference of a single hollow shaft member, with the angular positional difference being provided between the first and second flat surfaces, and forming the first rack on the first flat surface and the second rack on the second rack surface by press-fitting one or more mandrels into the hollow shaft member in a state in which one or more teeth dies corresponding to the first rack and the second rack is pressed against the first flat surface and the second flat surface.

Abstract: A snubber circuit unit for a power semiconductor module including an arm having two power semiconductor elements capable of switching which are connected in series, the power semiconductor module including a positive DC input terminal, a negative input terminal, and an output terminal which are electrically connected to the arm, the positive DC input terminal, the negative DC input terminal, and the output terminal being provided on an upper surface opposite to an installation surface of the power semiconductor module, the snubber circuit unit includes a circuit board, and a plurality of electronic components mounted on the circuit board.

Abstract: An apparatus for manufacturing a rack bar includes a pre-forming machine forming a flattened portion on an outer peripheral surface of a hollow shaft member, a teeth forming machine forming rack teeth on the flattened portion, a heat treatment machine quenching the rack teeth, a first conveying machine carrying the shaft member into and from the pre-forming machine, a second conveying machine carrying the shaft member into and from the teeth forming machine, and a third conveying machine carrying the shaft member into and from the heat treatment machine. The first conveying machine, the second conveying machine, and the third conveying machine hold one end of the shaft member from a radially inner side of the shaft member. The apparatus of the rack bar are suitable for manufacturing a relatively short hollow rack bar having rack teeth formed over substantially an entire length of a shaft member.

Abstract: A heating coil includes a plurality of loop portions disposed coaxially along an axis, a first lead portion and a second lead portion which electrically connect to a power source, and a connection portion which connects the plurality of loop portions, the first lead portion, and the second lead portion in series.

Abstract: A heating coil is configured to induction heat a workpiece having a hole. The heating coil includes first and second heating units respectively having conductors. The conductors of the first and second heating units extend in inclination directions intersecting an axial direction and a circumferential direction of an outer peripheral surface of the workpiece.

Abstract: An output current synthesizer that synthesizes output currents output from a plurality of power inverter circuits converting direct current power to alternating current power and outputs the synthesized output currents as synthesized current having a predetermined frequency, the output current synthesizer includes a pair of conductors which is provided with each of the power inverter circuits and to which the output currents of the power inverter circuits flow, a reactor which is provided on each of the pairs of conductors and generates magnetic flux corresponding to a difference between values of currents flowing to the pairs of conductors to reduce the difference between the values of currents, a pair of conductive members to which the pairs of conductors are connected in parallel, and a pair of output terminals which is provided on the pair of conductive members and output the synthesized currents.