| 摘要 |
The invention provides a cutting head for a drill bit, the cutting head comprising four substantially identically shaped cutting arms extending radially from a common central axial point, each cutting arm comprising a cutting edge extending outwardly and axially backwards from the common central axial point. The cutting edges are equiangularly spaced apart from each other about the central axis of the cutting head. Each cutting arm further comprises a side chamfer extending between its radially outer face and its rotationally trailing side face. |
