| 摘要 |
<p>A drill bit for connection to a drill string has a bit body (11) with an end cutting face (16), which supports a plurality of cutting elements (25). At least one nozzle passage (26) extends from the interior of the bit body (11) through the cutting face (16) for receiving a removable and interchangeable nozzle member (27) therein. The nozzle member (27) has a fluted or non-circular cross section with grooved portions or out of round portions providing sufficient clearance for drilling fluid to continue to flow through the nozzle even when the main passage thereof is blocked with mud particles or the like.</p> |
