Gear chamfering method, chamfering tool, and chamfering tool manufacturing method

A gear chamfering method comprising a chamfering step of chamfering, by a chamfering tool configured to be rotated about a tool axis, a gear having a plurality of teeth formed around a rotation axis, wherein

• each of the plurality of teeth has
• a tooth flank as a surface oriented in a circumferential direction of the gear and
• a border portion, in an axial direction of the rotation axis, of the tooth flank,
• the chamfering tool has at least one machining edge formed around the tool axis into a shape corresponding to a shape of the border portion,
• an arbitrary integer is represented by K, the number of the teeth is represented by Zw, and the number of the machining edges is represented by Zt, and
• the chamfering step includes performing K·Zt/Zw rotations of the gear about the rotation axis per rotation of the chamfering tool about the tool axis in a machining orientation in which the tool axis is set non-parallel to the rotation axis, and sequentially bringing the machining edge into contact with a plurality of the border portions to chamfer the border portions.