| 摘要 |
The drill bit (1) has only curved cutting edges (2), or a combination of a single straight cutting edge with two curved cutting edges. The cutting edges are aligned to start at the drill bit axis or end close to the axis. Three channels start at the blind drilling to mount the bit at the leading end of a self-tapping injection drill anchor rod, with the channel openings (11) at concave recesses (12) in the lateral surface of the drill bit which expands conically towards the cutting edges, so that they are recessed within the bit face. |
