| 摘要 |
A well bore enlarger comprising, in its fixed-arm embodiment, a tubular housing member having an enlarged section with an outer diameter substantially the same as the well bore diameter, the enlarged section having a plurality of longitudinal cut-out portions defining blades of the enlarged section therebetween; a longitudinal slot within the blade; a cutting arm mounted to the blade within the slot having cutting edges and a fluid gallery between the cutting edges which gallery communicates with the slot and the well bore; synthetic diamond material attached to the cutting arm; and means on the tubular housing member for directing a fluid through the fluid gallery of the cutting arm. In the expandable-arm embodiment of the well bore enlarger, the tubular housing member is formed with the enlarged section as previously described, with slots, blades and cut-out portions. The expandable-arm embodiment further comprises a cutting arm which is pivotally mounted within the blade and moveable between radially retracted position wherein the cutting arm is disposed essentially within the outer diameter of the enlarged section and a radially extended position wherein the outer edge of the cutting arm is disposed essentially outside the diameter of the enlarged section and the inner edge of the cutting arm remains at all times essentially within the outer diameter of the enlarged section; stop means within the blade and engageable with the cutting arm to limit outward movement of the cutting arm; synthetic diamond material attached to the cutting arm; a tubular drive member slidably mounted within the tubular housing member, the drive member including a piston actuated by hydraulic fluid; means on the cutting arm and drive member for moving the cutting arm from its retracted position to its extended position; and means on the drive member for directing fluid toward the cutting edges of the cutting arm.
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