| 摘要 |
PROBLEM TO BE SOLVED: To provide a low-cost cutting tap which exerts a sufficient cutting chips ejecting performance while a flexibility is secured for adjustment of the wound diameter and pitch of the cutting chips. SOLUTION: The tap 10 of spiral type is structured so that its threaded part 13 provided at the forefront of the shank part 11, has a biting part 14 with the ridges lowering gradually toward the forefront, and a complete ridge part 15 continued to the biting part and having approximately the same thread height, and is equipped with: a plurality of guide grooves 16 for ejection of cutting chips ranging approximately over the whole length of the threaded part and consisting of a twisted groove having approximately a circular arc section. A cutting edge groove 17 in the two-step arrangement having approximately a circular arc section for curling forcedly the chips cut by cutting edges is formed approximately over the whole length of the guide groove on that surface of the guide groove which is located on the rake face side of the cutting edge 18. COPYRIGHT: (C)2008,JPO&INPIT
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