Tools – Wrench – screwdriver – or driver therefor – Machine
Reexamination Certificate
2000-07-31
2001-08-21
Meislin, D. S. (Department: 3723)
Tools
Wrench, screwdriver, or driver therefor
Machine
C081S057350
Reexamination Certificate
active
06276238
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
None
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
Drill rods or pipes come in sections that are joined by male threads, tapered convergently, and female sockets, threaded and tapered internally complementarily to the male threads. The drill strings are rotated in a direction that tends to tighten the joints. That, plus the fact that the joints are liable to get gritty material between the threads, makes breaking the joints difficult. Various power mechanisms have been proposed and used (e.g., U.S. Pat. Nos. 4,345,493, 5,727,432). Where non-rotating vises have been employed, they have held the rod while a pipe wrench or the like has been used to turn the section that is not gripped by the vise. The wrench has been turned either manually or by some power mechanism. The pipe wrench type joint breakers have the disadvantage that the gripping surface is limited, putting extreme pressure in a limited area, and may not provide sufficient gripping force. Another approach to turning the free section has been to provide jaws sliding in a cradle rotated on a radius concentric with the radius of a pipe or rod clamped between the jaws. However, this construction has heretofore been subject to wear, with metal-to-metal contact, and a tendency to distortion, which leads to misalignment between the sections of the string.
One of the objects of this invention is to provide an improved open top rotating vise, in which there is substantially no wear or distortion, and in which the rotation of the rotating vice is facilitated.
Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawings.
BRIEF SUMMARY OF THE INVENTION
In accordance with this invention, generally stated, an open top rotating vise for use in breaking joints in a drill string is provided which comprises a cradle having side plates and end plates, and semi-circular bearing surfaces carried by and extending outboard from the side plates. A stand comprises side frame members extending parallel to the cradle side plates, and carrying anti-friction rollers extending inboardly from the side frame members. The rollers are arranged on a radius concentric with the radius of the semi-circular bearing surfaces in position to engage the bearing surface. Jaws carried by the cradle slide intermediate the side plates. Preferably, two sets of jaws, facing one another, are powered toward and away from one another. The rollers are of the nature of cam followers, with needle or roller bearings, each with an inside race mounted on a heavy stub shaft threaded at its outer end to receive a nut to hold the assembled rollers in place. Power means, such as a hydraulic cylinder, rock the cradle about the center axis of the bearing surface and rollers, which is coincident with the axial center line of the drill string.
In operation, one end of a drill string section is clamped between jaws of a stationary vise adjacent the rotating vise. The section to be disengaged is clamped between the jaws of the rotating vise, and the rotating vise is given a turn in the uncoupling direction, through a short angle, just enough to break the joint. Because the threaded sections are tapered, rotation of one segment with respect to its connected segment through a small angle, generally less than 30 degrees, is enough to free the two sections.
REFERENCES:
patent: 4345493 (1982-08-01), Rassieur
patent: 4870738 (1989-10-01), Rassieur
patent: 5727432 (1998-03-01), Burns et al.
Junck Todd A.
Mongillo Richard S.
Meislin D. S.
Polster Lieder Woodruff & Lucchesi L.C.
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