| 摘要 |
A drill bit 10 includes a body 12 having a face 20, a connection 15 and central longitudinal axis 11. Two types of cutter are provided in terms of geometry: a first cutting element (702, fig 7) and a second cutting element (704, fig 7). Each is mounted to the face at generally the same radial distance from the central axis. The two types of cutting element have different bevel sizes. Preferably, the two types of cutting elements have different backrake angles. The second cutting elements may have a larger bevel size and a less aggressive backrake angle. |
