Drill-bit with full offset cutter bodies

A rotary drill bit having a longitudinal axis for drilling in an earth formation, which drill bit includes at least one cutter body connected at end supports at either end of said cutter body to a main body structure in a fixed operative position for rotation about a rotational axis of said cutter body defined by said end supports, said rotational axis offset from and perpendicular to said longitudinal axis, said cutter body having cutting elements connected to flutes projecting above an outer surface of said cutter body in rows generally parallel to said rotational axis from one end to another end of said cutter body, said cutter body moveable in a primary direction of rotation wherein said cutting element rows intersect and abrade the earth formation generally along the rows and the longitudinal axis, and a secondary rotation induced by said primary rotation wherein said rows laterally intersect and abrade said earth formation.

A rotary drill bit for drilling in an earth formation, which drill bit includes a main body structure and at least one cutter body connected to the main body structure by an end support at each end of the cutter body, a plurality of cutter elements connected to said cutter body in spaced apart flutes on an outer surface of said cutter body, said flutes generally parallel to each other and to a rotational axis of said cutter body and extending along a line in a continuously changing angle with respect to a straight line, parallel to said rotational axis, connecting the ends of the cutter body, said rotational axis being perpendicular to and offset from a longitudinal axis of said drill bit, each end support of said cutter body being of essentially equal distance from said drill bit longitudinal axis, whereby rotation of said drill string in a primary direction about said longitudinal axis rotates said cutter body in a secondary rotational direction about its own rotational axis to abrade the earth formation.

In a drag type of rotary drill bit having a longitudinal axis and abrasive cutting elements rotatable about a rotational axis, said drill bit for drilling a bore into an earth formation by shearing cutting action on the earth formation, an improvement and combination therewith comprising:

• means for periodically moving each of said abrasive cutting elements about said rotational axis and into and out of contact with said earth formation during primary rotation of said drill bit in contact with the earth formation, said rotational axis offset from and perpendicular to said longitudinal axis, said periodic moving means further imparting both a radial component of abrading movement in the direction of primary rotation along the rotational axis and a circumferential component of abrading movement about said rotational axis to each cutting element in contact with the earth formation, the circumferential component being greater than the radial component.

In a drag type rotary drill bit having abrasive cutting elements for drilling an earth formation by shearing cutting action on the earth formation, an improvement and combination therewith comprising at least one cutter body rotatively mounted to a main body structure of said rotary drill bit, said cutter body having spiral flutes extending along the length of said cutter body, said flutes having abrasive cutting elements operatively associated therewith, said cutter bodies being rotated during a primary rotation of said drill bit into contact with the earth formation, said flutes contacting said earth formation to move said cutter body about a rotational axis of said cutter body offset from and perpendicular to a longitudinal axis of said drill bit, said primary rotation and said movement about said rotational axis imparting both a radial and a circumferential component of abrading movement to each cutting element while in contact with the earth formation, the circumferential component being greater than the radial component.

A rotary drill bit for drilling in an earth formation, which drill bit includes at least one cutter body having a bore formed along the length thereof for receipt of a shaft, said shaft fixedly connected to a main body structure at either end of said shaft at an end support position, a roller bearing assembly mounted intermediate said shaft and said cutter body bore, said shaft further having formed therearound an annular thrust bearing fitted into a counter-sunk bore, said cutter body having cutting elements connected to flutes projecting above an outer surface of said cutter body in rows from one end to another end of said cutter body, said cutter body moveable in a primary direction of rotation wherein said cutting element rows intersect and abrade the earth formation generally along the row and in a secondary rotation induced by said primary rotation wherein said rows laterally intersect and abrade said earth formation, said thrust bearing mounted at the end of said cutter body which precedes said cutter body in the primary rotational direction.