Heating coil, heating apparatus and manufacturing method of workpiece

[0025]FIG. 1 schematically illustrates an example of a heating coil and a heating apparatus for illustrating an embodiment. FIGS. 2 to 4 illustrate the heating coil in FIG. 1.

[0026]A heating apparatus 1 is a stationary heating apparatus that is configured to inductively heat an outer peripheral surface of a cylindrical workpiece W1. A hole H extending in a radial direction from the outer peripheral surface is formed in the workpiece W1. The hole H may be a through hole or a blind hole.

[0027]The heating apparatus 1 includes a heating coil 20 that is configured to inductively heat the outer peripheral surface of the workpiece W1, a power supply 2 that is configured to supply high frequency AC power to the heating coil 20, a supporting portion 3 that is configured to support the workpiece W1 and the heating coil 20, and a rotation driving unit 4 that is configured to rotate the workpiece W1 about a central axis X of the workpiece W1.

[0028]The heating coil 20 is configured such that a cond