| 摘要 |
A screw tap for forming a female screw in a workpiece, and a female screw forming method. A screw tap (1) formed so that a bottom portion (4) between crests (3, 3) contacts crest portions (22a) of a female screw (22), which is formed in a workpiece (20), with substantially no space left between the valley portion (4) and the ridge portions (22a). A female screw is formed in a workpiece by using such a screw tap (1), whereby a female screw having no burrs at both corner portions of a crest surface of a screw thread can be formed.
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