| 摘要 |
This rotary drill bit provides a plurality of spaced polycrystalline diamond compact cutter elements arranged at spaced 120° concentric rings around the face of the drill bit and a secondary, redundant deeper set polycrystalline diamond compact cutter elements placed to commence scuffing the face of a bore upon wear of the primary cutter element, thereby providing extended continuous service in hard rock drill applications previously unattainable with conventional PDC bits. |
