Floating wrench assembly for drill rig

A wrench assembly is mounted on a drill rig so as to have some freedom of movement in three axes. The wrench assembly includes a wrench subassembly having an upper wrench and a lower wrench. Both the upper wrench and the lower wrench are provided with jaw assemblies that are adapted to grip a pipe section or to release it. One of the upper wrench and lower wrench is pivotally moveable with respect to the other to apply a twisting force to a pipe section gripped by one of the upper and lower wrenches with respect to an adjacent pipe section gripped by the other of the upper and lower wrenches. The wrench assembly also includes a generally planar support table. The wrench subassembly is attached to the support table in such a manner as to allow the wrench subassembly to pivot about an axis that is perpendicular to the plane of the support table, and in such a manner as to allow the wrench subassembly to tilt with respect to the plane of the support table.

FIELD OF THE INVENTION

The present invention relates generally to drilling rigs that employ a drill string comprised of a plurality of drill pipes that are joined together in threaded engagement. More particularly, the invention comprises a wrench assembly that is used to tighten or loosen the threaded connection between a pair of adjacent drill pipes.

BACKGROUND OF THE INVENTION

Drilling rigs employ hydraulically actuated wrenches to tighten and loosen the threaded connections between drill pipes. These wrenches comprise two pairs of opposed jaws, one for the male-threaded pipe and the other for the female-threaded pipe of the adjacent components of the drill string. Each wrench is adapted to clamp around a pipe section, one above and the other below the threaded connection. At least one clamping component of the wrench assembly will pivot with respect to another clamping component so as to twist one of the pipe sections with respect to the other. There are two common problems that are not adequately addressed by conventional wrench assemblies. The first is misalignment of the drill pipe string with the wrench assembly due to one or more pipe sections being bent or misaligned. This condition interferes with the ability of the wrench assembly to clamp effectively onto the pipe sections and therefore jeopardizes the ability of the wrench to tighten or loosen the joint between adjacent pipe sections. The other problem arises from inadvertent axial movement (with respect to the drill string) of the drill rig carriage (on which the wrench assembly is mounted) while the clamping components of the wrench assembly are clamped onto the drill pipes. Such axial movement while the pipe sections are clamped can damage the drill pipes, the wrench assembly and other components of the drill rig.

It is known to provide wrench assemblies that are adapted for use with drill pipes of various diameters. Such assemblies are described in U.S. Patent Application Publication No. 2009/0255662 and U.S. Pat. No. 7,665,514. It is also known to provide wrench assemblies that are adapted for use with drill pipes having wall thicknesses that have become tapered through wear. Such assemblies are described in U.S. Pat. No. 6,938,519 and U.S. Pat. No. 6,814,149. It is also known to provide pipe guide assemblies that are adapted to guide or position a drill pipe for engagement by a pipe gripping apparatus. Such assemblies are described in U.S. Patent Application Publication No. 2009/0056930 and U.S. Pat. No. 7,090,254. Finally, U.S. Patent Publication No. 2010/0200258 describes a wrench assembly that is adapted to automatically disengage from the pipe sections if the pipe is raised or lifted, such as for example, if the operator inadvertently withdraws the pipe from the drill hole without first disengaging the wrench assembly.

It would be desirable, however, if a wrench assembly could be provided on a drill rig so as to have some freedom of movement in three axes. A preferred embodiment of such a wrench assembly would be self-orienting when clamped onto misaligned pipe sections, and it would also deflect without damage when an axial force is inadvertently applied while the wrenches of the assembly are clamped onto adjacent pipe sections of a drill string.

Notes on Construction

The use of the terms “a”, “an”, “the” and similar terms in the context of describing the invention are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising”, “having”, “including” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. The terms “substantially”, “generally” and other words of degree are relative modifiers intended to indicate permissible variation from the characteristic so modified. The use of such terms in describing a physical or functional characteristic of the invention is not intended to limit such characteristic to the absolute value which the term modifies, but rather to provide an approximation of the value of such physical or functional characteristic.

The use of any and all examples or exemplary language (e.g., “such as”) herein is intended merely to better illuminate the invention and not to place a limitation on the scope of the invention. Nothing in the specification should be construed as indicating any element as essential to the practice of the invention unless so stated with specificity.

Various terms are specifically defined herein. These terms are to be given their broadest possible construction consistent with such definitions, as follows:

The terms “lower” and “below” and similar terms of relative position refer to the part of the wrench assembly nearest the ground on which the drill rig is placed when drilling.

The terms “upper” and “above” and similar terms or relative position refer to the part of the wrench assembly opposite the lower part.

The term “linear actuator” refers to an electric, hydraulic or electro-hydraulic device that generates force which is directed in a straight line. One common example of a linear actuator is a fluid actuator which includes a cylinder, a piston within the cylinder, and a rod attached to the piston. By increasing the pressure within the cylinder on one side of the piston (over that on the opposite side of the piston), the rod will extend from the cylinder or retract into the cylinder.

The terms “pipe section”, “drill pipe section” and similar terms refer to a hollow tubular component that is provided with male threads on one end and corresponding female threads on the other, and is intended to be connected by threaded engagement, or is connected by threaded engagement, to an adjacent pipe section.

The terms “drill pipe”, “drill string” and similar terms refer to a plurality of pipe sections that are joined together by threaded engagement, with a drill bit or other boring component at the lower end thereof.

The term “adjacent pipe sections” and similar terms refer to a pair of pipe sections that are joined together by threaded engagement to form a part of a drill string, or are located or placed with respect to each other so as to be joined together in such manner, or have been disengaged from each other.

SUMMARY OF THE INVENTION

The invention comprises a wrench assembly that is mounted on a drill rig so as to have some freedom of movement in three axes. This allows the wrench assembly to be self-orienting when clamped onto misaligned pipe sections, and it also allows it to deflect without damage when an axial force is inadvertently applied while the wrenches of the assembly are clamped onto adjacent pipe sections of a drill string. Such wrench assembly comprises a wrench subassembly which includes an upper wrench and a lower wrench. Both the upper wrench and the lower wrench are provided with jaw assemblies that are adapted to grip a pipe section or to release it. One of the upper wrench and lower wrench is pivotally moveable with respect to the other to apply a twisting force to a pipe section gripped by one of the upper and lower wrenches with respect to an adjacent pipe section gripped by the other of the upper and lower wrenches, and means are provided for pivotally moving one of the upper wrench and the lower wrench with respect to the other. The wrench assembly also includes a generally planar support table, and means for attaching the wrench subassembly to the support table. One such means is adapted to allow the wrench subassembly to pivot about an axis that is perpendicular to the plane of the support table, and another such means is adapted to allow the wrench subassembly to tilt with respect to the plane of the support table.

In order to facilitate an understanding of the invention, the preferred embodiments of the invention, as well as the best mode known by the inventors for carrying out the invention, are illustrated in the drawings, and a detailed description thereof follows. It is not intended, however, that the invention be limited to the particular embodiments described or to use in connection with the apparatus illustrated herein. Therefore, the scope of the invention contemplated by the inventors includes all equivalents of the subject matter recited in the claims, as well as various modifications and alternative embodiments such as would ordinarily occur to one skilled in the art to which the invention relates. The inventors expect skilled artisans to employ such variations as seem to them appropriate, including the practice of the invention otherwise than as specifically described herein. In addition, any combination of the elements and components of the invention described herein in any possible variation is encompassed by the invention, unless otherwise indicated herein or clearly excluded by context.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

Referring now to the drawings, a first embodiment of the invention is illustrated inFIGS. 1-10. As shown therein, wrench assembly14includes wrench subassembly15comprised of upper wrench16and lower wrench17. Upper wrench16includes jaw assembly18having oppositely disposed linear actuators19that may be operated to close the jaws of the assembly to grip a pipe section or to open the jaws to release it. Lower wrench17includes a similar jaw assembly having linear actuators22that may be operated to close the jaws of the assembly to grip a pipe section or to open the jaws to release it.

The upper wrench is pivotally moveable with respect to the lower wrench about an axis that is perpendicular to the plane ofFIG. 2, so that when the lower wrench grips a pipe section and the upper wrench grips an adjacent pipe section, the upper wrench can be pivoted to apply a twisting force to the pipe section gripped by the upper wrench with respect to the adjacent pipe section gripped by the lower wrench. In the alternative, the lower wrench may be moveable with respect to the upper wrench, so that when the upper wrench grips a pipe section and the lower wrench grips an adjacent pipe section, the lower wrench can be pivoted to apply a twisting force to the pipe section gripped by the lower wrench with respect to the adjacent pipe section gripped by the upper wrench.

Means are provided to pivotally move the upper wrench with respect to the lower wrench. As best shown inFIG. 2, such means comprise linear actuator23, which has a base end24that is attached to lower wrench17and a rod end25that is attached to upper wrench16. In the alternative (although not shown in the drawings), the rod end of a linear actuator could be attached to the lower wrench and the base end to the upper wrench. By actuating linear actuator23in the embodiment shown inFIGS. 1-10, the upper wrench can be pivoted with respect to the lower wrench to apply the twisting force described above to loosen or tighten the threaded connection between adjacent pipe sections.

As described in more detail hereinafter, means are provided for attaching wrench subassembly15to generally planar support table26in such a way that it may pivot, preferably both to the left and to the right (as viewed inFIG. 2), about an axis that is perpendicular to the plane of the support table to properly orient the jaws of the wrenches when attempting to clamp onto misaligned pipe sections. In addition, means are provided for attaching wrench subassembly15to generally planar support table26in such a way that it may tilt with respect to the plane of the support table, to compensate for an inadvertent axial force that is applied to the drill rig or to the wrench assembly while the wrenches are clamped onto adjacent pipe sections of a drill string. Preferably, such tilting means allow the wrench subassembly to tilt through an angle of at least about 6° with respect to the plane of the support table. More preferably, such tilting means allows the wrench subassembly to tilt upwardly on the left side (as viewed from the perspective ofFIG. 2), upwardly on the right side, or upwardly by lifting both sides through the same tilt angle. It is also preferred that support table26be moveable with respect to underlying frame27. As best shown inFIGS. 1 and 2, support table26is provided with a plurality of wheels or rollers28that are adapted to roll along left and right roller paths29of frame27. A pair of linear actuators30are mounted between frame27and support table26to move the support table with respect to the frame. Thus, the support table may be moved laterally, by actuating linear actuators30, to center the wrench subassembly on the theoretical drill string axis. An open center valve (not shown) in fluid communication with linear actuators30allows for relatively free motion about that axis in the event that the adjacent pipe sections to be engaged by the wrench assembly are not aligned with the theoretical axis. Furthermore, the invention allows support table26to pivot about an axis that is perpendicular to the plane of the support table to properly orient the jaws of the wrenches when attempting to clamp onto misaligned pipe sections, and to tilt with respect to the plane of the support table to compensate for an inadvertent axial force that is applied to the drill rig or to the wrench assembly while the wrenches are clamped onto adjacent pipe sections of a drill string.

In the embodiment of the illustrated inFIGS. 1-10, generally planar support table26includes support plate32that is provided with a first angled slot34and a second angled slot36(shown inFIGS. 6 and 8). Wrench subassembly15includes bearing plate38, and support table26includes pivot shaft40. Spherical bearing42is placed over pivot shaft40and is adapted to be received in bearing hole44(shown inFIG. 4) in bearing plate38. Washer45is placed atop the spherical bearing and nut46is threaded onto pivot shaft40to secure the wrench subassembly thereon.

A first shoulder bolt and a second shoulder bolt (only one of which is shown in the drawings) are provided for placement through the angled slots. Thus, as shown inFIGS. 1,9and10, first shoulder bolt48is placed through slot34in support plate32. Preferably, a flat washer such as washer49is placed over the shoulder bolt before it is inserted through the appropriate slot. Mounted atop the lower wrench on the shoulder bolts are a plurality of tilt washers, such as spring washers or Belleville washers50, a flat washer51and a securing nut52, shown inFIGS. 9 and 10. The illustrated combination of angled slots34and36and the shoulder bolts comprise a pivoting stop mechanism that allows the wrench subassembly to pivot to the left or right about an axis that is generally perpendicular to the plane of the support table and through the center of spherical bearing42. In the embodiment of the invention that includes the angled slots and shoulder bolts, the wrench subassembly may pivot by at least about one inch from the center of slots34and36to compensate for a misaligned drill string or misaligned pipe sections. The tilt washers are stacked in a non-parallel fashion or otherwise arranged so that the combination of the spherical bearing, shoulder bolts and tilt washers allow the wrench subassembly to tilt through a preferred angle of at least about 6°, as measured from the plane of the support table, to compensate for inadvertent axial forces. Preferably, the wrench subassembly is adapted to tilt upwardly on either the left or the right side, or on both sides, with respect to the plane of the support table.

An alternative embodiment of the invention is illustrated inFIGS. 11-13. As shown therein, wrench assembly114includes wrench subassembly115comprised of upper wrench116and lower wrench117. Upper wrench116includes a jaw assembly that is essentially identical to jaw assembly18of upper wrench16of wrench assembly14. The jaw assembly of upper wrench116includes oppositely disposed linear actuators119that may be operated to close the jaws of the assembly to grip a pipe section or to open the jaws to release it. Lower wrench117includes a similar jaw assembly having linear actuators122that may be operated to close the jaws of the assembly to grip a pipe section or to open the jaws to release it.

The upper wrench is pivotally moveable with respect to the lower wrench, so that when the lower wrench grips a pipe section and the upper wrench grips an adjacent pipe section, the upper wrench can be pivoted to apply a twisting force to the pipe section gripped by the upper wrench with respect to the adjacent pipe section gripped by the lower wrench. In the alternative, the lower wrench may be moveable with respect to the upper wrench, so that when the upper wrench grips a pipe section and the lower wrench grips an adjacent pipe section, the lower wrench can be pivoted to apply a twisting force to the pipe section gripped by the lower wrench with respect to the adjacent pipe section gripped by the upper wrench.

Means are provided to pivotally move the upper wrench with respect to the lower wrench. As best shown inFIG. 12, such means comprise linear actuator123, which has a base end that is attached to the lower wrench and a rod end that is attached to the upper wrench. In the alternative (although not shown in the drawings), the rod end of a linear actuator could be attached to the lower wrench and the base end to the upper wrench. By actuating linear actuator123in the embodiment ofFIGS. 11-13, the upper wrench can be pivoted with respect to the lower wrench to apply the twisting force described above to loosen or tighten the threaded connection between adjacent pipe sections.

Means are also provided for attaching wrench subassembly115to generally planar support table126in such a way that it may tilt with respect to the plane of the support table, to compensate for an inadvertent axial force that is applied to the drill rig or to the wrench assembly while the wrenches are clamped onto adjacent pipe sections of a drill string. Preferably, such tilting means allow the wrench subassembly to tilt through an angle of at least about 6° with respect to the plane of the support table. More preferably, such tilting means allows the wrench subassembly to tilt upwardly on the left side, upwardly on the right side, or upwardly by lifting both sides through the same tilt angle. It is also preferred that support table126be moveable with respect to underlying frame127. As best shown inFIG. 11, support table126is provided with a plurality of wheels or rollers128that are adapted to roll along left and right roller paths of frame127. A pair of linear actuators130are mounted between frame127and support table126to move the support table with respect to the frame. Thus, the support table may be moved laterally, by actuating linear actuators130, to center the wrench subassembly on the theoretical drill string axis. An open center valve (not shown) in fluid communication with linear actuators130allows for relatively free motion about that axis in the event that the adjacent pipe sections to be engaged by the wrench assembly are not aligned with the theoretical axis. Furthermore, the invention allows support table126to pivot about an axis that is perpendicular to the plane of the support table to properly orient the jaws of the wrenches when attempting to clamp onto misaligned pipe sections, and to tilt with respect to the plane of the support table to compensate for an inadvertent axial force that is applied to the drill rig or to the wrench assembly while the wrenches are clamped onto adjacent pipe sections of a drill string.

Wrench subassembly115includes a bearing plate (not shown, but essentially identical to bearing plate38of wrench subassembly15), and support table126includes a pivot shaft (also not shown, but essentially identical to pivot shaft40of wrench assembly14). A spherical bearing (not shown but essentially identical to spherical bearing42of wrench assembly14) is placed over the pivot shaft and is adapted to be received in a bearing hole (also not shown, but essentially identical to bearing hole44that is shown inFIG. 4) in the bearing plate. A washer is placed atop the spherical bearing and a nut is threaded onto the pivot shaft to secure the wrench subassembly thereon.

A pivoting stop mechanism for this embodiment of the invention comprises a pair of weldments148and associated stop brackets150. Weldments148are attached to lower wrench117and stop brackets150are attached to support table126. The stop brackets include bracket base151, bracket upright152and bracket arm154. As shown inFIG. 13, each bracket arm154is arranged to clear its associated weldment148by distance “Y”, thus allowing for tilting of the wrench subassembly with respect to support table126. Distance “X” indicates the clearance between bracket base151and weldment148when the wrench subassembly is centered with respect to support table126. Distance “X” on either side of the wrench subassembly allows for pivotal movement of the wrench subassembly through a limited range before either of weldments148abuts its associated bracket base151. The illustrated combination of weldments148and stop brackets150comprise a pivoting stop mechanism that allows the wrench subassembly to pivot to the left or right about an axis that is generally perpendicular to the plane of the support table and through the center of the spherical bearing. Such pivotal motion allows the wrench assembly to compensate for a misaligned drill string or misaligned pipe sections.

Although this description contains many specifics, these should not be construed as limiting the scope of the invention, but as merely providing illustrations of some of the presently preferred embodiments thereof, as well as the best mode contemplated by the inventors of carrying out the invention. The invention, as described herein, is susceptible to various modifications and adaptations, as would be understood by those having ordinary skill in the art to which the invention relates, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.