| 摘要 |
A three-cone rock bit employing a non-plugging center jet nozzle with a plurality of staggered inlet orifices leading to side passageways to reduce bit balling. The nozzle defines a tapered cavity through which drilling mud flows and exits in streams. Streams are directed from the nozzle through a main exit aperture of sufficient size to avoid plugging and from side passageways boring through a sidewall of the nozzle. Jetting streams promote washing of voids within the bit and of cutting surfaces. The nozzle uses staggered inlet orifices leading to side passageways, in conjunction with a tapering shape of a central passageway to facilitate maintenance of drilling mud velocity within the central passageway and thus of stream velocity to targeted regions of the drill bit. The present invention additionally provides a method of using the drill bit and non-plugging nozzle by controlling velocities of drilling mud within the nozzle.
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