| 摘要 |
A helical gear having helical tooth portions of the helical gear being worked by a punch and a die having a land of a smaller distance between opposed working surfaces formed to be inclined than that of other portion, formed on predetermined portions in tooth directions of respective opposed working surfaces thereon, in which worked surfaces on both side of the helical tooth portions on the helical gear as a work are ironed by the land in response to the helical tooth portions passing through the land when the work is forged by the punch.
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