Tools – Wrench – screwdriver – or driver therefor – Machine
Reexamination Certificate
1999-11-04
2001-05-15
Hail, III, Joseph J. (Department: 3723)
Tools
Wrench, screwdriver, or driver therefor
Machine
C175S052000, C173S189000
Reexamination Certificate
active
06230590
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a remotely operated tool for making and breaking the threaded connection between a drill head and a stabilizer mounted on the end of a drill string.
2. Description of the Related Art
Raise boring is a method of underground rock drilling used in the mining industry. This method involves drilling a pilot hole from one level of a mine to a lower level, removing the pilot bit, attaching a larger diameter raise boring head to the drill string and pulling it back through the previously drilled pilot hole. Finally, the raise boring head is lowered back down to the lower level, where the raise boring head is removed from the drill string.
Typically, the drill string is composed of a plurality of pipe sections which are secured to each other by threaded connections. The drill string typically terminates at a stabilizer unit, to which is connected the pilot bit during the first phase of the operation, and the raise boring head during subsequent phases of the raise boring operation. The threaded connections within the drill string are designed to transmit the “working torque” load between the drilling rig on the upper mine level and the pilot drill or raise boring head. However, the connections must be preloaded at a torque up to approximately 20% greater than the working torque. All of the connections within the drill string are preloaded by the drilling rig, except for the connection between the stabilizer and the raise boring head.
Detaching the pilot drilling head, and attaching and detaching the raise boring head involves the use of torque tools to “break” and “make” the rotary shouldered threaded connections between the respective heads and the stabilizer. These torque tools are also used to generate the necessary pre-loading torque. Various torque tools have been developed for this purpose. See, for example, Canadian Patents Nos. 910,895; 927,374; 929,510; 988,502; 1,004,215; 1,009,225; 1,112,683; and Canadian Patent Application No. 2,156,560 (published May 19, 1996). These references describe respective systems for making and breaking the joint between pipe sections of a drill string, and are also usable for making and breaking the joint between the drill head and the stabilizer unit at the end of the drill string.
However, as demonstrated by the systems taught by the above references, known torque tools require that at least a portion of the mechanism surrounds the drill string. Thus in each case, the torque tools must be installed around the drill string prior to use. Problems which exist with this installation are generally safety issues. Primarily, the torque tool equipment is heavy and working conditions often make it awkward and unsafe for men to work. Once the raise boring operation is complete, the raise boring head must be detached from the drill string, and this typically requires that workers must stand on the raise boring head to attach the torque tools, thereby exposing the men to the dangers associated with working under the open hole. In order to alleviate these problems, additional equipment can be installed to protect the men from falling rock. However, these measures are expensive and time consuming.
An object of the present invention is to provide a method and apparatus for making and breaking the threaded connection between a drill head and a stabilizer mounted on the end of a drill string, which overcomes the above-noted deficiencies of the prior art.
Another object of the invention is to provide a method and apparatus for making and breaking the threaded connection between a drill head and a stabilizer mounted on the end of a drill string, such that the need for men to work under an open hole is substantially eliminated.
SUMMARY OF THE INVENTION
Accordingly, an aspect of the present invention provides an apparatus for making and breaking a threaded connection between a drill head and a stabilizer mounted on an end of a drill string. The apparatus comprises a wrench capable of operatively engaging a portion of the drill head so as to substantially prevent rotation of the drill head with respect to the wrench. A gripper assembly is operatively mounted on the wrench. The gripper assembly is capable of operatively receiving a portion of the stabilizer, and releasably locking the stabilizer against rotation relative to the gripper assembly. Finally, at least one drive unit is operatively coupled between the gripper assembly and the wrench for driving rotational movement of the gripper assembly with respect to the wrench.
In an embodiment of the invention, the gripper assembly comprises a generally C-shaped housing defining an gripper mouth for receiving the stabilizer; and at least one gripper operatively mounted within the housing for releasably engaging a rib of the stabilizer.
In an embodiment of the invention, the gripper comprises a shoe mounted for substantially radial movement with respect to a longitudinal axis of a stabilizer disposed within the gripper mouth, and extension means for forcibly moving the shoe inwardly and outwardly to respectively lock and unlock the stabilizer against rotation relative to the gripper assembly.
In an embodiment of the invention, the extension means is any one of an hydraulic ram and a pneumatic ram.
In an embodiment of the invention, there are 4 grippers substantially evenly separated for each other within the housing of the gripper assembly, the grippers acting cooperatively to releasably lock and unlock the stabilizer against rotation relative to the gripper assembly.
In an embodiment of the invention, the wrench comprises a generally C-shaped body defining a wrench opening capable of operatively receiving a portion of the drill head, the wrench opening being substantially co-extensive with the mouth of the gripper housing when the apparatus is view from above.
Preferably, the wrench opening is sized to receive and operatively engage opposed wrench-flats of the drill head, whereby rotation of the drill head with respect to the wrench is substantially prevented. In an embodiment of the invention, a back wall of the wrench opening is provided such that, when drill head is slid into the wrench opening and a wrench flat of the drill head contacts the back wall, then the central axis of the drill string will be substantially coextensive with a centroid of the wrench opening.
In an embodiment of the invention, the wrench comprises a pair of opposed guide faces oriented so as to automatically guide a drill string into the mouth of the gripper assembly and wrench opening as the assembly is moved toward the drill string.
In an embodiment of the invention, the drive unit comprises at least one hydraulic ram operatively coupled to the wrench and the gripper assembly, such that rotation of the wrench can be effected by extension and/or retraction of the hydraulic ram. Alternatively, the drive unit can comprise at least one pneumatic ram operatively coupled to the wrench and the gripper assembly, such that rotation of the wrench can be effected by extension and/or retraction of the pneumatic ram.
In an embodiment of the invention, the apparatus is operatively mounted on the end of an arm, such that the apparatus can be remotely maneuvered into position around the drill head and stabilizer.
REFERENCES:
patent: 4117894 (1978-10-01), Saunders
patent: 5653297 (1997-08-01), Whisenhunt
patent: 5778742 (1998-07-01), Stuart
patent: 5791206 (1998-08-01), Daigle et al.
patent: 6012360 (2000-01-01), Concha
patent: 910895 (1972-09-01), None
patent: 927374 (1973-05-01), None
patent: 929510 (1973-07-01), None
patent: 988502 (1976-05-01), None
patent: 1004215 (1977-01-01), None
patent: 1009225 (1977-04-01), None
patent: 1112683 (1981-11-01), None
patent: 2156560 (1995-08-01), None
Finnegan Henderson Farabow Garrett & Dunner
Hail III Joseph J.
Mining Technologies International Inc.
Thomas David B.
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