| 摘要 |
A composite drill bit with a bit body configured at its upper extend for connection into a drillstring, comprising: a bit body (1) with at least one bit leg (3), at least one scraping-wheel (2) set with a cutter-row (4), and a set of cutters fixed thereon. The scraping-wheel (2) is mounted for rotation on the corresponding bit leg (3) with a large angular deflection alpha in the range of 20°@|alpha|@90°. The cutters on the scraping-wheel break rock by means of successive scraping, forming a cross-cutting area on the bottomhole accompanied by the cutters on the fixed cutting unit, thus achieving high rock-breaking efficiency, even wear, high cooling performance, and a longer service life for the cutters, bearings and the drill bit.
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