TAP Russian patent published in 1997 - IPC

FIELD: mechanical engineering; machining of parts; cutting internal threads. SUBSTANCE: cutting part 1 and calibrating part 2 of tap are made with low sections 4 lateral sides of profile and on flank; cutting and calibrating teeth 7 have section which is not low on side of face 6; width "a" of this section is equal to at least 0.1 mm but no more than 0.012 D^1,8, where D is tap nominal diameter. EFFECT: enhanced efficiency. 4 dwg, 2 tbl