| 摘要 |
A rotary drill bit for drilling earthen formations is provided with a plurality of discrete cutting teeth disposed on the lower face of the bit body and arranged in circumferentially spaced, generally radially extending rows. Each of the teeth has a large diamond (or a diamond-like material) set in its leading face at its peak and may have the balance of its leading face as well as its sides provided with smaller flush mounted diamonds. Alternatively, the teeth can be provided with a synthetic diamond or a sintered diamond facing which can extend to the peaks thereof. Fluid courses extend from a central passage in the bit along the leading faces of the teeth so as to discharge fluid against these leading faces and wash the cuttings away therefrom into the valleys between adjacent ones of the teeth. In one aspect, the teeth are mounted on lands on the bit body and recessed areas are provided between the lands so that the primary pressure drop of the fluid will be in the vicinity of the teeth thereby enhancing the action of the drilling fluid in moving the cuttings from in front of the teeth and through the valleys therebetween into the recessed areas.
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