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公开(公告)号：EP0066435A1
公开(公告)日：1982-12-08
申请号：EP82302641.4
申请日：1982-05-24
CPC分类号： E21B10/567 , E21B12/04
摘要： A rotary drill bit (10, 12) for drilling earth formations has a plurality of cutting elements (16) mounted on the head portion of the bit. The bit further includes a plurality of individual protrusions (20) projecting from the head portion more than the extension of the cutting element (16). The protrusions (20) are fabricated of a metal more readily abraded by the earth formation than any of the cutting elements (16). The protrusions (20) protect the cutting elements (16) during handling of the bit and entry of the bit into a borehole; and. the protectors (20) are abraded away to expose the cutting elements (16) during drilling.
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