摘要 |
A drill bit assembly for direct removal of rock with a rotatable bit assembly ( 5 ) that includes a plurality of cutters or choppers ( 7 ). According to the invention, an number of cutters ( 7 ) are so disposed in relation to each other or the bit assembly ( 5 ) that a subsequent cutter ( 7 b), seen in the direction of rotation, will engage an edge created by the action of preceding cutter ( 7 a). |