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: 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: A heating coil includes a pair of linear lead portions adapted to be connected to a power supply, and a ring-shaped or coil-shaped head portion having end portions connected to the lead portions respectively. A flow path through which a cooling medium flows is formed inside the lead portions and the head portion. An outer circumferential surface of the head portion has a circular or elliptical cross section and is configured to face a heating target portion of an inner circumferential surface of a work extending, the heating target portion extending in a circumferential direction of the work. Each of the lead portions has a straight side portion in a plane intersecting a longitudinal direction of the lead portions, the straight side portions of the lead portions being arranged in proximity to each other.

Abstract: Heating coils are opposed to a portion of an annular workpiece having a continuously provided recessed surface, and the heating coils and the annular workpiece are moved relative to each other to heat the recessed surface by induction heating. The heating apparatus includes a first heating coil having a first corner conductor portion to be opposed to a first corner portion of the recessed surface and a first bottom conductor portion connected to the first corner conductor portion to be opposed to the bottom portion, and a second heating coil having a second corner conductor portion to be opposed to a second corner portion of the recessed surface and a second bottom conductor portion connected to the second corner conductor portion to be opposed to the bottom portion.

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: 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: 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: 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: Heating coils are opposed to a portion of an annular workpiece having a continuously provided recessed surface, and the heating coils and the annular workpiece are moved relative to each other to heat the recessed surface by induction heating. The heating apparatus includes a first heating coil having a first corner conductor portion to be opposed to a first corner portion of the recessed surface and a first bottom conductor portion connected to the first corner conductor portion to be opposed to the bottom portion, and a second heating coil having a second corner conductor portion to be opposed to a second corner portion of the recessed surface and a second bottom conductor portion connected to the second corner conductor portion to be opposed to the bottom portion.

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: 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: 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 one end side portion is nipped by a jig including a jig member having a pair of convex portions which are to be fitted to a depressions in contact with a tooth side face and a inclined portion and positioning a bar and a jig member which is to be clamped/opened with respect to the jig member. A die having an inside diameter smaller than the diameter of the outer periphery is pressed onto the outer periphery of the end portion of the cylindrical end side portion projected from the jig up to a press-in depth determined preliminarily based on the rack, so as to reduce the diameter of the end portion.

Abstract: The one end side portion is nipped by a jig including a jig member having a pair of convex portions which are to be fitted to a depressions in contact with a tooth side face and a inclined portion and positioning a bar and a jig member which is to be clamped/opened with respect to the jig member. A die having an inside diameter smaller than the diameter of the outer periphery is pressed onto the outer periphery of the end portion of the cylindrical end side portion projected from the jig up to a press-in depth determined preliminarily based on the rack, so as to reduce the diameter of the end portion.

Abstract: The one end side portion is nipped by a jig including a jig member having a pair of convex portions which are to be fitted to a depressions in contact with a tooth side face and a inclined portion and positioning a bar and a jig member which is to be clamped/opened with respect to the jig member. A die having an inside diameter smaller than the diameter of the outer periphery is pressed onto the outer periphery of the end portion of the cylindrical end side portion projected from the jig up to a press-in depth determined preliminarily based on the rack, so as to reduce the diameter of the end portion.

Abstract: The one end side portion is nipped by a jig including a jig member having a pair of convex portions which are to be fitted to a depressions in contact with a tooth side face and a inclined portion and positioning a bar and a jig member which is to be clamped/opened with respect to the jig member. A die having an inside diameter smaller than the diameter of the outer periphery is pressed onto the outer periphery of the end portion of the cylindrical end side portion projected from the jig up to a press-in depth determined preliminarily based on the rack, so as to reduce the diameter of the end portion.

Abstract: The one end side portion is nipped by a jig including a jig member having a pair of convex portions which are to be fitted to a depressions in contact with a tooth side face and a inclined portion and positioning a bar and a jig member which is to be clamped/opened with respect to the jig member. A die having an inside diameter smaller than the diameter of the outer periphery is pressed onto the outer periphery of the end portion of the cylindrical end side portion projected from the jig up to a press-in depth determined preliminarily based on the rack, so as to reduce the diameter of the end portion.

Abstract: In an induction heating coil for heating a shaft member having multiple steps, annular conductors are separately disposed in the axis direction, the annular conductors having inner diameters so as to form predetermined gaps with outer peripheries of heating portions of the shaft member, the lengths of annular conductors (1, 2, and 3) are set so that the areas of the respective heating portions are approximately equal to each other, and the annular conductors are connected to each other in series, so that the respective step shaft portions of the shaft member are uniformly heated. The annular conductors described above may be formed to have shapes in conformity with the shapes of the heating portions of the shaft member and may be formed to have a step shape corresponding to steps of the shaft member having different outer diameters.

Abstract: The one end side portion is nipped by a jig including a jig member having a pair of convex portions which are to be fitted to a depressions in contact with a tooth side face and a inclined portion and positioning a bar and a jig member which is to be clamped/opened with respect to the jig member. A die having an inside diameter smaller than the diameter of the outer periphery is pressed onto the outer periphery of the end portion of the cylindrical end side portion projected from the jig up to a press-in depth determined preliminarily based on the rack, so as to reduce the diameter of the end portion.

Abstract: In an induction heating coil for heating a shaft member having multiple steps, annular conductors are separately disposed in the axis direction, the annular conductors having inner diameters so as to form predetermined gaps with outer peripheries of heating portions of the shaft member, the lengths of annular conductors 1, 2, and 3 are set so that the areas of the respective heating portions are approximately equal to each other, and the annular conductors are connected to each other in series, so that the respective step shaft portions of the shaft member are uniformly heated. The annular conductors described above may be formed to have shapes in conformity with the shapes of the heating portions of the shaft member and may be formed to have a step shape corresponding to steps of the shaft member having different outer diameters.