| 摘要 |
In one aspect of the present invention, a drill bit has an axis of rotation and a working face with a plurality of blades extending outwardly from a bit body. The blades form in part an inverted conical region and a plurality of cutters with a cutting surface are arrayed along the blades. A jack element is coaxial with the axis of rotation and extend within the conical region within a range defined by the cutting surface of at least one cutter.
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