| 摘要 |
<p>A rotary drill bit, for use in subsurface formations, comprises a bit body, a passageway for drilling fluid within the body, communicating with nozzles in the external surface of the body, preform cutting elements mounted on the body for cutting or abrading the formation, and a number of elongate fences upstanding from the external surface of the body to control the flow of fluid from said nozzles and past cutting elements. Each fence includes a plurality of resiliently deformable elements disposed adjacent one another in a direction across the width of the fence, for example being in the form of a brush having metal bristles, so that, in use, the free elongate edge of the fence is urged resiliently into contact with the surface of the formation being cut or abraded by the cutting elements. Since each fence is resiliently deformable it will at all times firmly engage the formation to provide an effective seal, regardless of variations in depth of cut of the cutting elements.</p> |
