Barrel-shaped threaded tool for machining internal gear
An object is to provide a barrel-shaped threaded tool for machining an internal gear which is capable of machining with high accuracy by appropriately setting a helix angle. To achieve the object, in a threaded grinding wheel ( 11 ) formed into a barrel shape having a diameter gradually decreasing from an axially intermediate portion thereof toward axially opposite end portions thereof so that the threaded grinding wheel ( 11 ) is meshed with a workpiece (W) with a crossed axes angle (Σ) therebetween during the machining of the workpiece (W), the helix angle is set in accordance with the length from the axially intermediate portion.
1. A barrel-shaped threaded tool for machining an internal gear, the barrel-shaped threaded tool being formed into a barrel shape having a diameter gradually decreasing from an axially intermediate portion of the barrel-shaped threaded tool toward axially opposite end portions thereof so that the barrel-shaped threaded tool is meshed with a to-be-machined internal gear with a crossed axes angle therebetween during machining of the to-be-machined internal gear, wherein
the tool having a helix angle that increases with increasing axial length from the axially intermediate portion.
2. The barrel-shaped threaded tool according to claim 1 , wherein
an increment of the tool helix angle gradually increases with increasing axial length from the axially intermediate portion.