| 摘要 |
A drill bit (10) for use in unconsolidated formations includes a generally triangular cross-section that tapers toward the lower tip end (34) of the tool (10). The vertices of the triangular cross-section carry blade members (22, 23, 24) that cut and define the size of the bore hole. Nozzles (45, 46, 47, 48) positioned between the blades (22, 23, 24) upon the tapered portion (66) of the tool and on the uppermost surface of the drill head break up unconsolidated formation material that has been cut. Tooth-like projections (20) or inserts (120) made of materials such as tungsten carbide and polycrystalline diamonds and the like are carried on the blades and spaced apart from one another so that each blade makes a one-third cut into the formation during a single rotation of the drill head. |
