| 摘要 |
PCT No. PCT/GB83/00227 Sec. 371 Date May 10, 1984 Sec. 102(e) Date May 10, 1984 PCT Filed Sep. 16, 1983 PCT Pub. No. WO84/01186 PCT Pub. Date Mar. 29, 1984.A rotary bit for use in subsurface formations comprises a bit body having a central bore (4), the body having a leading face (1) and a trailing gauge region (2), walls (7) on the bit dividing the face into fluid channels, cutting elements C being present on at least some of the walls, and passageways (5) connecting the bore (4) to openings (6) in the fluid channels. At least two wall portions (7) are arranged relative to each openings (6) so that the fluid emerging from the opening is directed to travel first inwardly towards the central axis of the bit before travelling outwardly to the gauge region (2).
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