| 摘要 |
1. Tap composed of a conical cutting part (3) relieved on flanks of threads (6) and, if appropriate, on crests (7), provided with flutes (5) for removing the chips towards the front of or inside the tap and extended by a rear part (4) which is cylindrical or very slightly conical, with a conicity opposite to that of the conical cutting part (3), and which is threaded to the nominal diameter D and to the profile of the final hole, characterised in that the said rear part (4) has a profile consisting of an alternation of sectors of two types (8) and (9), the flanks of threads of the sectors (8) having the profile of the final hole and the flanks of threads of the sectors (9) being relieved in relation to the profile of the final hole. |
