| 摘要 |
A full bore drag type well drilling bit including a bit body comprised of a generally non-frangible metallic material. The bit body has an operating end face defined by said metallic material to include a plurality of upsets each having a leading edge and at least one recess extending through such leading edge into said metallic material. The end face further includes a plurality of flow paths, each of the leading edges of the upset having one such flow path extending therealong and inset therefrom. At least some of the upsets have a plurality of such recesses spaced therealong. A plurality of circulation ports open through the end face of the bit body, the number of circulation ports being less than the number of flow paths extending along the leading edges of the upsets, and at least some of the ports communicate with more than one such path. The bit further comprises a plurality of cutting structures carried by the bit body. Each cutting structure includes an elongate mounting body and a cutting formation on the exterior of the mounting body adjacent one end thereof. At least a majority of the mounting bodies of the bit are mounted in respective ones of the recesses in the upsets with their cutting formations facing outwardly along the leading edges of the upsets.
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