| 摘要 |
A rotary drill bit for drilling a borehole in an earth formation is provided. The drill bit comprises a plurality of cutting elements (7, 9) arranged to cut a plurality of substantially circular, radially spaced cuts (22, 24, 26) into the bottom of the borehole, the cutting elements including at least one cutting/shearing element (7), each cutting/shearing element being arranged so as to cut into the bottom of the borehole at an angular interval behind another one of said cutting elements (9). A body of rock material (28) is defined between the trajectories of the cuts created by the cutting/shearing element and said other cutting element. The cutting/shearing element is provided with means for shearing-off said body of rock material in the direction of the cut created by said other cutting element. |
