| 摘要 |
PURPOSE:To prevent production of burrs being apt to produce at an opening edge part, by a method wherein, in prior to taper machining of a taper plug for gas cock, chamfering machining is applied on at least the opening edge part on the one side in a circumferential direction of the opening end of a through-hole. CONSTITUTION:In prior to taper machining, chamfering machining is applied on at least an opening edge part 6 on the one side in a circumferential direction of the opening end of a through-hole 3 to form the opening edge part 6 in the shape of an obtuse angled projected part. A cutter 7 is used for chamfering machining, and in the opening edge part 6 of the opening end, either the one side or the other side is chamfered to provide an obtuse angled projected part. When subsequent taper machining is effected by means of a cutter 5, burrs, being apt to produce in the case of a conventional acute angled projected part, are prevented from production especially in relation to the right opening edge part 6 on a peripheral surface.
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