专利名称：Core bit having axial conical core breaker发明人：Robert Jerome申请号：US05/892357申请日：19780331公开号：US04207954A公开日：19800617
摘要：A drilling tool comprising a body having a leading face with a central recessproviding the body with an annular leading cutting edge such that during drilling acentral core is formed, and a central cone positioned axially in the recess for breaking upthe core.
申请人：FRANCAISE DES PETROLES CIE
代理机构：Sughrue, Rothwell, Mion, Zinn and Macpeak
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