DRILL BIT Russian patent published in 1997 - IPC

FIELD: drilling equipment. SUBSTANCE: this relates to drilling deep bore-holes of large diameter and can be used in combination with rock crushing tools of rolling cutter type. Drill has body in the form of set of weighted members, rock crushing tool located under lower end of body, and calibrator installed under rock crushing tool. It is provided with weighted drill pipes with their axes located in one plane. Body in its cross-section is made in the form of oval or rectangular with rounded corners or rhomb or part of circle limited by parallel chords located symmetrically relative to large sectional axis. Rock crushing tool is in the form of journal-mounted rolling cutters of spherical-taper configuration with tops of tapers directed towards central part of drill on axes of journals located in axial plane at angle to drill axis within 30-90 deg. Calibrator is double-blade, secured on body and located in plane which is perpendicular to plane of location of large cross-sectional axis of body and rolling cutters. Maximal size of body cross-section in relation to drill diameter is within following relation: 0,87 ≅ a/D ≅ 0,97,, where a - maximal cross-sectional dimension of body, mm; D - drill diameter, mm. Planes of location of rolling cutters are at acute angle to plane of location of large axis of body cross section. EFFECT: high efficiency. 1 cl, 6 dwg