| 摘要 |
<p>A drill bit (4) has a head with a diameter D (51). The head includes a tip (13) with only one cutting edge (52) extending over part of the diameter. It has a V-shaped side groove (59) for cuttings removal. A channel (12) has an opening (56) in the head, delivering cutting fluid. On the side opposite the groove, between first and second cylindrical outer surfaces (64, 65) there is a relief (63) cut back into the cylindrical outer surface (62) describing the head. The length to diameter ratio of the head is 0.5 to 10, or 1 to 4. A surface normal (67) of the relief (63) intersects the groove bisector, to include an angle of -50[deg] to +50[deg], preferably -30[deg] to + 30[deg]. The relief is in an end region facing the tip, and has axial extent. A width to diameter ratio of the relief is 0.1 to 0.8. The relief runs continuously in the direction of the tip. It is alternatively parallel to the axis of the head. Two or more reliefs may be included. The cutting fluid circuit is described. Drilling fluid is supplied at up to 4000 bar. An independent claim is included for drilling.</p> |
