TAP Russian patent published in 2004 - IPC

FIELD: metal working, thread cutting. SUBSTANCE: tap includes working parts with starting and calibrating portions. Lateral profile of teeth of starting portion and of first turn of calibrating portion is lowered; their inner diameters are arranged on cone reciprocal to that of starting portion. In order to enhance strength of tap and quality of thread, working part has guiding zone and lateral profile of teeth of starting portion and first turn of calibrating portion may be lowered at both sides. Inner diameters of said teeth are arranged on cylinder whose diameter is equal to inner diameter of one turn of starting portion or of first turn of calibrating portion. EFFECT: improved quality of thread, enhanced strength of tap. 2 cl, 1 dwg