Patent ID: 8777696

Claim:
A machining method for a concave-convex gear, concave teeth of the concave-convex gear and convex teeth of a mating gear being continuously formed in a circumferential direction, and the concave teeth meshing with the convex teeth of the mating gear to allow torque transmission to or from the mating gear, wherein the concave-convex gear is machined from a disc-shaped workpiece, the concave-convex gear is a gear that rotates about an intersecting axis that intersects with a rotation central axis of the mating gear, a sectional shape of an outer peripheral surface of each convex tooth of the mating gear in a direction orthogonal to a reference axis of the convex tooth is formed in a circular arc shape, a relative movement trajectory of each convex tooth of the mating gear with respect to the concave-convex gear at the time when torque is transmitted between the mating gear and the concave-convex gear is expressed by: a first linear axis along which a reference position of the convex tooth of the mating gear is moved in a direction orthogonal to a plane that is tangent to a concave tooth forming face of the disc-shaped workpiece; a second linear axis along which the reference position of the convex tooth of the mating gear is moved in a tooth groove direction of a corresponding one of the concave teeth of the concave-convex gear in the plane that is tangent to the concave tooth forming face of the disc-shaped workpiece; a third linear axis along which the reference position of the convex tooth of the mating gear is moved in a direction orthogonal to the second linear axis in the plane that is tangent to the concave tooth forming face of the disc-shaped workpiece; a fourth rotation axis along which the reference position of the convex tooth of the mating gear is rotated about the first linear axis; a fifth rotation axis along which the reference position of the convex tooth of the mating gear is rotated about the third linear axis; and a sixth indexing axis that coincides with a rotation central axis of the concave-convex gear and that indexes a rotation phase of the concave-convex gear, the machining method characterized by comprising: calculating the relative movement trajectory of each convex tooth of the mating gear, expressed by the first linear axis, the second linear axis, the third linear axis, the fifth rotation axis and the sixth indexing axis when the fourth rotation axis is brought into coincidence with the sixth indexing axis; and moving at least one of the disc-shaped workpiece and a working tool on the basis of the calculated relative movement trajectory.