Gear machining apparatus

A gear machining apparatus comprising:

• a machining tool including a tool edge having a plurality of protruding tool edges on an outer periphery of the machining tool;
• and
• a driving apparatus that forms a tooth on a work piece by rotating the machining tool around a central axis thereof, rotating the work piece around a central axis thereof, and moving the machining tool relative to the work piece;
• wherein
• the driving apparatus sets the central axis of the machining tool and the central axis of the work piece in a skew state, and drives the machining tool straight ahead in a direction of the central axis of the machining tool toward the work piece while synchronizing rotation of the work piece with rotation of the machining tool so as to allow the protruding tool edges to form the tooth on the work piece, and
• radial outer faces of the protruding tool edges form multiple steps that are parallel to the central axis of the machining tool such that a diameter of the machining tool increases in a stepwise manner from a tool leading end toward a tool base end of the machining tool, wherein
• the machining tool is formed such that circumferential widths of the radial outer faces of the protruding tool edges decrease in a stepwise manner from the tool leading end toward the tool base end of the machining tool, the radial outer faces forming the multiple steps such that the diameter of the machining tool increases in a stepwise manner.