| 摘要 |
A rotary drill bit has an upper rotatable main body member which rotates respective to a lower stationary bit member. The lower stationary bit member has an axial centerline arranged at an angle respective to the axial centerline of the upper body member. The lower face of the lower bit member terminates in a formation engaging surface which is in the form of a cone so that as the drill string imparts rotation into the main body member, the face of the lower member engages the formation and is wobbled by the action of the rotating main body. This action forces a limited area along one side of the conical face to bear against the formation. The formation engaging portion of the bit face travels circumferentially about the bit due to the eccentricity or misalignment of the two bit members. The wobble action imparts great pressure on the bottom of the borehole, increases penetration of the bit, and reduces wear on the cutting elements of the bit face.
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