| 摘要 |
<p>A drill tool includes a bit body, at least one bearing shaft extending from the bit body and a cone mounted for rotation on the bearing shaft. An outer bearing surface of the bearing shaft includes a non-loading zone. A first groove and a second groove are formed in the outer bearing surface at the non-loading zone. The first and second grooves are both circumferentially offset from each other and axially offset from each other. One or more of the grooves includes an opening for making a fluid connection to an internal lubricant channel within this bearing shaft. The circumferential and axial offsetting of the first and second grooves define a plurality of attenuation zones that function to restrict propagation of a cone pumping pressure pulse towards a sealing system of the drill tool.</p> |
