Abstract: An apparatus is provided to measure a depth of a hardened layer formed at a surface layer of a quenched workpiece. The apparatus includes an exciting coil configured to generate a magnetic flux to magnetize the workpiece and a detecting coil configured to detect the magnetic flux generated by the exciting coil. The exciting coil has a U-shaped excitation core portion and an excitation coil portion wound on the excitation core portion. The excitation core portion is arranged such that distal ends of magnetic poles of the excitation core portion face the workpiece. The detecting coil has a detection core portion and a detection coil wound on the detection core portion. The detection core portion is arranged between the magnetic poles of the excitation core portion and along a surface of the workpiece.

Abstract: Provided are a method of manufacturing a hollow rack bar including a rack portion that is engaged with a pinion gear and faces supported by a yoke easily and accurately, and the hollow rack bar. The hollow rack bar (10) includes: the rack portion (21) engaged with the pinion gear (29); and the supported faces (23) provided on a back side of teeth of the rack portion (21) and supported by the yoke (31). The rack portion (21) is formed by locating a toothed mold (39) on an outer face of a circular tube material, and inserting a cored bar (41) into the circular tube material to pressurize an inner face, thereby transferring a shape of the toothed mold (39). The supported faces (23) are formed by removal processing or deformation processing of a back side of the teeth rack portion (21) of the circular tube material.

Abstract: A heating apparatus, a heat treatment apparatus, and a heating method are provided. The heating apparatus includes a workpiece support on which a ring-shaped workpiece is placed, a rotary drive assembly, and a heater configured to heat the workpiece. The workpiece support includes a plurality of rotating rollers arranged in a circumferential direction. The rotary drive assembly is configured to rotate the plurality of rotating rollers to rotate the workpiece placed on the workpiece support along a ring shape of the workpiece. The heater includes a heating coil configured to induction-heat the workpiece on the workpiece support at a heating position, and an actuator configured to move the heating coil at the heating position relative to the workpiece to adjust a distance between the workpiece and the heating coil.

Abstract: A workpiece for an induction hardening is provided. The workpiece has a first inclined surface, a second inclined surface, and a connecting surface connecting the first inclined surface and the second inclined surface on a side toward which the first inclined surface and the second inclined surface approach each other. The connecting surface has a recessed portion. A hardened layer formed at the first inclined surface and another hardened layer formed at the second inclined surface do not overlap each other at the recessed portion.

Abstract: A wire heating system includes an induction heating apparatus having a power supply and an induction coil arranged to heat a wire rod by an induction heating using current supplied from the power supply, and a controller configured to control the current to be supplied to the induction coil based on a feeding speed of the wire rod. The induction heating apparatus has a heating section in which the wire rod is heated by the induction heating using the induction coil, and a soaking section located downstream of the heating section to homogenize the temperature distribution of the induction-heated wire rod. The controller is configured to control the current to be supplied to the induction coil such that a temperature of the wire rod at a downstream end of the soaking section becomes a target temperature.

Abstract: Object of the present invention is to provide a welding method prevented the fracture at the spot welding zone by recovering the strength of a spot welding zone, namely, the ductility and the toughness in the spot welding zone, and a weld structure manufactured by the method. In the welding method, a spot welding zone provided with a weld nugget is formed by conducting spot welding on the heat treated steel sheets in a stack; the spot welding zone is tempering treated by the high-frequency electrical current application to make the weld nugget have a hardness of 150% or less of the hardness of the heat treated steel sheets, and the heat affected zone surrounding the weld nugget is made to have a hardness of 30% to 90% of the hardness at the weld nugget before the tempering treatment by the high-frequency electrical current application.

Abstract: A power conversion apparatus and a power conversion method are provided. The power conversion apparatus includes a rectifier configured to convert AC power to DC power, a smoothing filter configured to control the DC power received from the rectifier to be constant, an inverter configured to convert the DC power received from the smoothing filter into high-frequency power by turning the DC power on and off using a switching device, and a control unit configured to control the rectifier and the inverter. A rating of output power from the inverter is determined in accordance with a frequency of the high-frequency power output from the inverter, a current-applying time, and an operation rate obtained by dividing the current-applying time by a sum of the current-applying time and a non-current-applying time.

Abstract: A power semiconductor module, a snubber circuit for the power semiconductor module, and induction heating power supply apparatus having the power semiconductor module are provided. The power semiconductor module includes a power semiconductor device configured to perform a switching operation, a casing inside which the power semiconductor device is provided, a control circuit board provided on top of an upper surface of the casing, a control terminal for the power semiconductor device being provided on the upper surface of the casing and connected to the control circuit board, and a shield plate disposed between the control circuit board and the upper surface of the casing to cover the upper surface of the casing and to cover at least one side surface of the casing.

Abstract: To heat a workpiece having a recess portion provided along a longitudinal axis of the workpiece, the workpiece is inserted into an induction heating coil, and the induction heating coil or the workpiece is along an axial direction of the workpiece. The induction heating coil has a conductor configured to surround the workpiece around the axis of the workpiece. The conductor has a protruding portion protruding inwardly to face the recess portion of the workpiece.

Abstract: Object of the present invention is to provide a welding method prevented the fracture at the spot welding zone by recovering the strength of a spot welding zone, namely, the ductility and the toughness in the spot welding zone, and a weld structure manufactured by the method. In the welding method, a spot welding zone provided with a weld nugget 13a is formed by conducting spot welding on the heat treated steel sheets in a stack; the spot welding zone is tempering treated by the high-frequency electrical current application to make the weld nugget have a hardness of 150% or less of the hardness of the heat treated steel sheets, and the heat affected zone surrounding the weld nugget is made to have a hardness of 30% to 90% of the hardness at the weld nugget before the tempering treatment by the high-frequency electrical current application.

Abstract: An induction heating coil (3) has a primary coil (4) to which electric power is supplied and a ring-shaped secondary coil (5) forming a closed circuit. The primary coil (4) has a base-side portion that covers an outer periphery of the secondary coil (5) and a distal-side portion extending from the base-side portion in the center axis direction of the secondary coil (5) in a state in which the base-side portion covers the secondary coil (5). The opening width of the base-side portion is greater than the opening width of the distal-side portion. The secondary coil (5) is provided such that it can be inserted into and removed from the inside of the primary coil (4) from the base-side portion of the primary coil (4).

Abstract: A direct resistance heating method includes placing a first electrode and a second electrode on a plate-shaped workpiece such that the first electrode and the second electrode extend across the workpiece in a direction substantially perpendicular to a center line of a heating target region of the workpiece, the center line connecting a middle portion of one side of the heating target region and a middle portion of the other side of the heating target region; and moving at least one of the first electrode and the second electrode along the center line while applying electric current between the first electrode and the second electrode.

Abstract: In a direct resistance heating method, a current is applied to a plate workpiece having a varying cross-sectional area to heat the workpiece such that a high-temperature heating region and a non-high-temperature heating region are provided side by side. The method includes a preparation step of arranging a pair of electrodes on the workpiece, and a heating step of moving a first electrode from one end of the high-temperature heating region while applying a current to the pair of electrodes, stopping the movement of the first electrode when the first electrode reaches the other end of the high-temperature heating region, and stopping the current from being applied to the pair of electrodes when a predetermined time elapses after stopping the first electrode. A press-molded product manufacturing method includes pressing the workpiece that has been heated by direct resistance heating method using a press die to perform hot press molding.

Abstract: A method for spot-welding metallic materials includes: sandwiching the metallic materials with a pair of electrodes; a pre-heating step for pre-heating a region different from a given region which should be welded by applying electric power having a high frequency to the pair of electrodes; and a welding step for spot-welding a given region of the metallic materials by applying electric power for welding to the pair of electrodes. The heating time in the pre-heating step and that in the welding step are independently controlled.

Abstract: A power conversion apparatus and a power conversion method are provided for heat treatment. The power conversion apparatus includes a rectifier configured to convert AC power to DC power, a smoothing filter configured to control the DC power received from the rectifier to be constant, an inverter configured to convert the DC power received from the smoothing filer into high-frequency power by turning the DC power on and off using a switching device made of an SiC semiconductor, and a control unit configured to control the rectifier and the inverter. A rating of output power output from the inverter is determined in accordance with a frequency of the high-frequency power output from the inverter, a current-applying time, and an operation rate obtained by dividing the current-applying time by a sum of the current-applying time and a non-current-applying time.

Abstract: A welding equipment for metallic materials capable of performing heat treatment such as tempering based on partial heating in spot welding is provided. The welding equipment sandwiches metallic materials with a pair of electrodes, and heats different regions of the metallic materials by energization, with the pair of electrodes maintained at the same position with respect to the metallic materials. The welding equipment includes a first heating means connected to the pair of electrodes for heating and welding the internal region of the circle defined by projecting the cross-sectional area of the axis of the electrodes on the metallic materials by applying power having a low first frequency, a second heating means for heating a ring-shaped region along the circle by applying power having a second frequency that is higher than the first frequency, and an energization control unit for independently controlling the first and the second heating means.

Abstract: An induction heating power supply apparatus includes a smoothing section to smooth pulsating current of DC power output from a DC power supply section, and an inverter to convert the DC power smoothed by the smoothing section to AC power. The smoothing section includes a pair of bus bars connected to the inverter and a capacitor connected to the pair of bus bars. Each of the bus bars has an external surface extending in a current flow direction, the external surface including a flat face having a larger surface dimension than another face of the external surface in a direction perpendicular to the current flow direction. The bus bars are arranged in a layered manner such that the flat faces of the bus bars are opposed to each other and such that an insulator is sandwiched between the flat faces of the bus bars.

Abstract: An induction heating, power supply apparatus includes a smoothing section to smooth DC power and an inverter section to convert the smoothed DC power into AC power, The inverter section has first and second modules, each having serially connected switching devices. Output bus bars are interposed between the first and second modules. The smoothing section has first bus bars connected to a DC power supply section and the first module, a capacitor connected to the first bus bars, second bus bars connected to the DC power supply section and the second module, and another capacitor connected to the second bus bars. The first and second bus bars extend parallel to the output bus bars. The first module is interposed between the first bus bars and the output bus bars. The second module is interposed between the second bus bars and the output bus bars.

Abstract: An induction heating system includes induction heating apparatuses, each including a high-frequency current transformer, a low-frequency current transformer and a heating coil, a high-frequency input switch connected to the high-frequency current transformer, a low-frequency input switch connected to the low-frequency current transformer, a first power source to output a high-frequency electric power and a low frequency electric power, a second power source, a first power source output switch connectable to the first power source, a second power source output switch connectable to the second power source, and a switch controller. Each induction heating apparatus includes a heater controller to send a signal to the switching controller to turn on one of the first power source output switch and the second power source output switch, to turn off the other, and to switch on or off each of the high-frequency input switch and the low-frequency input switch.

Abstract: The core metal for resin welding improves bonding strength between an outer peripheral resin member and the core metal. The outer peripheral resin member 30 is welded to the peripheral surface 21 of the core metal 20 by fitting the core metal into a fitting hole 31 of the outer peripheral resin member 30, preparing the outer peripheral resin member 30 providing the fitting hole 31 with a smooth internal wall surface; preparing the core metal 20 wherein streaky protrusions 26 and smooth portions 25 are provided; allowing the top parts of the protrusions 26 to contact, and the smooth portions of the core metal 20 to face the smooth internal wall surface; and induction heating to weld the outer peripheral resin member 30 to the protrusions 26 and the smooth portions 25.