In the method according to the invention, a wire (11) provided with teeth (15) passes sequentially through a first inductor (16) and a second inductor (18). The inductors (16, 18) function at different frequencies and generate different temperatures. The first inductor (16) heats in particular the base section (17), which is not to be hardened, to a high temperature below the austenitizing temperature range. The second inductor (18) heats the teeth (15) to a still higher second temperature within the austenitizing temperature range. Defined, hardened teeth of consistently high quality result at quenching.

In the method according to the invention, a wire (11) provided with teeth (15) passes sequentially through a first inductor (16) and a second inductor (18). The inductors (16, 18) function at different frequencies and generate different temperatures. The first inductor (16) heats in particular the base section (17), which is not to be hardened, to a high temperature below the austenitizing temperature range. The second inductor (18) heats the teeth (15) to a still higher second temperature within the austenitizing temperature range. Defined, hardened teeth of consistently high quality result at quenching.

Provided is a heat treatment apparatus (1), including: a heating unit (2), which is configured to inductively heat a workpiece (W) to a target temperature; and a drive mechanism, which is configured to move a plurality of the coaxially held workpieces (W) relative to the heating unit (2) being in an energized state in an axial direction of the workpiece (W), wherein the heating unit (2) includes: a plurality of coil members (11) respectively including a ring-shaped coil portion (11a) arranged coaxially with the workpiece (W) so as to be capable of surrounding the workpiece (W); and a frame body (21), which is configured to support each of the plurality of coil members (11) so as to be movable in the axial direction of the workpiece while maintaining the coaxial arrangement between the coil portions (11a).

Provided is a heat treatment apparatus (1), including: a heating unit (2), which is configured to inductively heat a workpiece (W) to a target temperature; and a drive mechanism, which is configured to move a plurality of the coaxially held workpieces (W) relative to the heating unit (2) being in an energized state in an axial direction of the workpiece (W), wherein the heating unit (2) includes: a plurality of coil members (11) respectively including a ring-shaped coil portion (11a) arranged coaxially with the workpiece (W) so as to be capable of surrounding the workpiece (W); and a frame body (21), which is configured to support each of the plurality of coil members (11) so as to be movable in the axial direction of the workpiece while maintaining the coaxial arrangement between the coil portions (11a).

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.

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.

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.

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.

Provided is a heat treatment apparatus (1), including: a conveying device (10), which is configured to convey a rod-shaped workpiece (W) at a predetermined velocity along an axial direction of the workpiece (W); and a heating device (2) including a heating coil (3) configured to inductively heat the workpiece (W) being conveyed to a quenching temperature, wherein the heating coil (3) includes a first heating section (3A) and a second heating section (3B), which are coupled to each other in series along the axial direction of the workpiece (W), and is electrically connected to a single high-frequency power supply (4), and wherein a coil pitch (D2) of the second heating section (3B) arranged relatively on a front side in a conveying direction for the workpiece (W) is larger than a coil pitch (D1) of the first heating section (3A) arranged relatively on a rear side in the conveying direction.

Provided is a heat treatment apparatus (1), including: a conveying device (10), which is configured to convey a rod-shaped workpiece (W) at a predetermined velocity along an axial direction of the workpiece (W); and a heating device (2) including a heating coil (3) configured to inductively heat the workpiece (W) being conveyed to a quenching temperature, wherein the heating coil (3) includes a first heating section (3A) and a second heating section (3B), which are coupled to each other in series along the axial direction of the workpiece (W), and is electrically connected to a single high-frequency power supply (4), and wherein a coil pitch (D2) of the second heating section (3B) arranged relatively on a front side in a conveying direction for the workpiece (W) is larger than a coil pitch (D1) of the first heating section (3A) arranged relatively on a rear side in the conveying direction.