Pin drill bit for percussive drilling

摘要

In a pin drill bit for percussive horizontal drilling by means of a down-the-hole hammer, with bit edging arranged on an end face as well as lateral flushing grooves on a drill head of the pin drill bit, a tapered-ring section (16k) adjoins a central section (16z), crossing the drill-bit axis (A), of the end face (16). The radius (f) of the tapered-ring section (16k) is more than twice the radius (e) of the central section at a taper angle (w) with the drill-bit axis (A) of about 50 to 70 DEG . In this arrangement, the flushing grooves (30, 30a) project into the tapered-ring section and the latter as well as the central section are provided with the bit edging (18). <IMAGE>