| 摘要 |
A rock drill bit comprising a shank fitted with a clamping end and a drilling tip at the end away from the clamping end, the drilling tip comprising at least three, preferably exactly three blades which are alar in topview, said blades each comprising at their top side a lip constituted by a leading chipping face and a trailing flank, the lips substantially converging onto each other within a central zone centered on the drill bit axis, characterized in that, in the central zone, a single lip—long lip—runs through the bit axis and comprises a commensurate overshoot segment extending beyond the bit axis.
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