| 摘要 |
PROBLEM TO BE SOLVED: To provide a cold forming tap reducing imperfect thread by forming a straight hole in nuts, a machine tool, a plate, or the like by cold forming tap machining. SOLUTION: A flank angle of a tip part 8 of the cold forming tap 1 differs between inside 4 and outside 3, and the outside 3θ1 has a constant angle, while the inside 4θ2 is gradually reduced with respect to a lead to have the same angle on the inside 31 and outside 3 on the way. A fill is gradually built up almost only on one side, and the fill is drawn to the inlet side to reduce the imperfect thread 5'. The number of crests with different angles on the inside 4 and outside 3 of the tap 1 is formed from 2 to 10 crests with the angle ofα. With cold forming machining applied to the straight hole in the nuts, machine tool, plate, or the like using the tap 1, the imperfect thread can be reduced, and galling and seizure caused by oblique built-in can be effectively prevented. COPYRIGHT: (C)2005,JPO&NCIPI
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