CA2917571A1

CA2917571A1 - Jaw assembly

Info

Publication number: CA2917571A1
Application number: CA2917571A
Authority: CA
Inventors: William A. ZEPEDA; Philip Chase JOHNSON
Original assignee: MCCOY GLOBAL Inc
Current assignee: MCCOY GLOBAL Inc
Priority date: 2013-07-08
Filing date: 2014-04-24
Publication date: 2015-01-15
Also published as: EP2999843A1; CA2917346A1; WO2015003241A1; WO2015003242A1; EP2999844A1

Abstract

A jaw assembly is taught, said jaw assembly comprising a lever arm defining a lever arm pocket on a top surface thereof, said lever arm pocket having sides and a bottom face, a cam roller moveable along a cam surface and a die holder removably and pivotably received in the lever arm pocket and having a gripping surface for gripping the tubular, said die holder having sides and a base. Movement of the cam roller along the cam surface serves to pivot the die holder within the lever arm pocket.

Description

Jaw Assembly Field of the Invention The present invention relates to a jaw assemblies for gripping tubulars.
Background Hydrocarbon wells are typically drilled to a selected depth in order to intersect a hydrocarbon bearing geological formation. While the depth of these formations is typically several thousands of feet, the practical manufactured length of pipe used for drilling and casing these wells is generally no more than forty feet.
Therefore, it is necessary to construct the required long strings of pipe using short sections with threaded connections at each end.
As the hydrocarbons in deep formations can generate pressures over ten thousand pounds per square inch and the weights of pipe strings used in drilling and casing wells may weigh millions of pounds, it is essential that the threaded connections be able to reliably withstand these pressures and tensile loads. The threaded connections must also be able to be reliably disconnected and reconnected should problems occur in the drilling and casing of hydrocarbon wells.
Equipment used in the make up and breakout of drilling and casing tubulars include casing running tools, tongs and bucking units. Jaw assemblies in these tools grip the tubular and some cases, rotate the tubular to make up or break out the string. As the jaw assembly grip force is necessarily high, it is important that the tubular surface not become damaged by the gripping surfaces, or dies, or the jaw assembly.
Such damage often occurs when the die surfaces do not properly contact the tubular surface, causing points of high force that tend to gouge the tubular surface, and points of no contact at all, resulting in incomplete gripping. As well, tubulars and couplings to be gripped are not perfectly circular and often have surface imperfections that can prevent full, even contact of the die surface with the tubular or coupling surface.
Again poor contact in turn leads to improper gripping, possible slippage during make up and breakout operations and possible damage to the tubulars and couplings.
It is also desirable to be able to utilize a singular jaw assembly for a range of tubular diameters, with only need to change out the dies. This reduces non-operational time needed to set up the make up or break out tool and improves the efficiency at which a variety of tubulars can be made up or broken out.
Some jaw designs have been created to allow movement of the die-carrying jaw on a pivot point that in turn pivots on geared sections of the jaw assembly.
In such designs, a first edge of a die surface contacts the tubular first and then the jaw assembly pivots to make further contact between the die and the tubular. Torque and force from the gripping and rotation of the tubular is transferred through the singular fulcrum of the pivot point to the make up or break out tool. Furthermore, when two of the jaw assemblies have pivoted to grip the tubular, further jaws are effectively prevented from pivoting, and held into position by virtue of the positioning of the first two jaw assemblies.
Therefore, there is a need for improved technology for reliably making and breaking these tubular connections to the stringent specifications of manufacturers and threading operations. Furthermore, there is a need for an apparatus that can grip tubulars with greater precision and more flexibility than present tools.
Summary A jaw assembly is taught, said jaw assembly comprising a lever arm defining a lever arm pocket on a top surface thereof, said lever arm pocket having sides and a bottom face, a cam roller moveable along a cam surface and a die holder removably and pivotably received in the lever arm pocket and having a gripping surface for gripping the tubular, said die holder having sides and a base. Movement of the cam roller along the cam surface serves to pivot the die holder within the lever arm pocket.
Brief Description of the Drawings The present invention will now be described in greater detail, with reference to the

2 following drawings, in which:
Figure 1 is a perspective view of a detail of one embodiment of the jaw assembly of the present invention;
Figure 2 is a side elevation view of one embodiment of the jaw assembly of the present invention;
Figure 3 is a bottom perspective view of one embodiment of the jaw assembly of the present invention;
Figure 4 is a top perspective view of one embodiment of the jaw assembly of the present invention; and;
Figure 5 is a side elevation view of one embodiment of the jaw assembly of the present invention, showing the circular path of swivel movement of the die holder within the lever arm pocket;
Figure 6 is a sectional elevation view of one embodiment of the jaw assembly of the present invention on a cam surface of a gripping tool; and Figure 7 is a sectional view of one example of a backup assembly, showing the jaw assembly of the present invention in a retracted position.
Description of the Invention The jaw assemblies of the present invention are advantageously designed to make up or break out tubulars and couplings of a range of outside diameters (OD).
They can be used in any number of tools including but not limited to casing running tools, tongs and bucking units, and collectively referred to as gripping tools for the purposes of the present invention.
A self-aligning jaw mechanism is preferably provided on each jaw assembly to compensate for irregularities in pipe size, shape and surface and also provide sufficient clearance when the jaws are retracted to accommodate a variety of tubular and coupling sizes. The clearance provided by the present jaw assembly makes it possible to

3 load couplings first into the gripping tool while still allowing adequate clearance for any misalignment.
With reference to Figures 1-6, the present jaw assembly 2 comprises a jaw roller 26 rotatably received in a lever arm 80. More preferably the jaw roller 26 is rotatably affixed to the lever arm 80 by means of a jaw pin 100 preferably retained by a retaining ring 110. An 0-ring 112 is preferably further included to prevent ingress of debris between the jaw roller 26 and the lever arm 80. The lever arm 80 further comprises a channel 82 that travels over cam surfaces 28 of a gripping tool. A lever arm pocket 84 is formed on the lever arm 80 as well.
A die holder 86 is removably positioned within the lever arm pocket 84, and is preferably pivotably held in place by a retaining clip 98 or other suitable means known in the art. The die holder 86 can be fitted with different sizes of dies 88 for contact with and gripping of tubulars 12 of different sizes to be made up or broken out. In an unengaged and neutral position, the die holder 86 preferably defaults to rest in a position in which both first end 90 and second end 92 of the die 88 protrude equally from the lever arm 80 into the central bore 14.
Preferably, one or more spring plungers 96, and more preferably four spring plungers 96, one in each corner of a bottom face 102 of the lever arm pocket 84 serve to bias the die holder 86 in this neutral position.
When the jaw assembly 2 is retracted by movement of the jaw assembly 2 along the cam surface 28 for insertion of a tubular 12 or coupling, a biasing means 94 is provided to urge one of either the first end 90 or the second end 92 of the die 88 towards the central bore 14, thereby causing a swivel movement of die holder 86 in the lever arm pocket 84. The orientation of a slope of the cam surface 28 of the gripping tool and the protrusion of one end of the die 88 maximizes clearance in the bore 14 to accommodate tubulars 12 and couplings into the bore 14. The present orientation of the die 88 when the jaw assembly 2 is in the retracted position provides maximum clearance between the die 88 and the tubular 12 to be inserted. This clearance allows for loading and unloading tubulars 12 in an automated process. For illustrative

4 purposes only, an example of a jaw assembly in a retracted position in the embodiment of a backup wrench assembly is depicted in Figure 7.
It would be well understood by a person of skill in the art that while first and second ends 90, 92 are assigned as left and right ends respectively in the Figures, that the assignment of these ends is completely random and that in a different cam surface slope design, the second end 92 can just easily be the end to protrude without departing from the scope of the present invention.
More preferably the biasing means 94 takes the form of a free moving push rod that may protrude from the bottom surface 102 of the lever arm pocket 84 and into channel 82. As the jaw assembly 2 moves into a retracted position, said push rod comes into contact with the cam surface 28 and as a result the push rod is pushed against a base 104 of the die holder 86 to actuate the swivel movement. In a most preferred embodiment, movement of the push rod serves to provide approximately 2" of diametric clearance for tubulars and couplings entering the machine.
As the jaw assembly 2 then moves along the cam surface 28 to grip the tubular 12, the biasing means 94 loses contact with the cam surface 28, thereby removing any push against the second end 92 of the die 88 and allowing the die holder 86 to swivel back to its neutral position, aided by the bias of the spring plungers 96.
As the jaw assembly 2 moves along the cam surfaces 28, to grip the tubular 12, contact of the tubular 12 with the die holder 86 preferably overcomes the biasing action of the one or more spring plungers 96, to swivel and position the die holder 86 as needed to ensure full contact with and gripping of the tubular 12. The swiveling movement of the die holder 86 in the lever arm pocket 84 is advantageous as it allows for better contact with the tubular or coupling in the presence of irregularities on the surface of the tubular 12 or coupling to be gripped.
In a preferred embodiment, as illustrated in Figure 5, the base 104 of the die holders 86 that contacts the bottom face 102 of the lever arm pocket 84 are each shaped to allow the die holder 86 to swivel within the lever arm pocket 84 to adjust to fit around the tubular 12 or coupling to be gripped. More preferably, the circular arc of

5 swivel movement of the base 104 of the die holder 86 in the bottom face 102 of the lever arm pocket 84 is concentric to the circular arc of swivel movement of the sides of the die holder 86 within the sides of the lever arm pocket 84. The concentric relationship of these swivel arcs is illustrated in Figure 5.
This concentric relationship of the swivel arcs provides the desired movement in a compact jaw assembly 2 size. Furthermore, the present design of die holder 86 and lever arm pocket 84 provides several load bearing surfaces to accommodate the high gripping loads, as well as the torque.
The sides and base 104 of the die holder 86 are always in contact with corresponding sides and bottom face 102 of the lever arm pocket 84, allowing for load from gripping and rotating the tubular 12 to be transmitted directly from the die face 88 to the lever arm 80 and the jaw assembly 2. More specifically, the sides of the die holder 86 transmit torque forces to the jaw assembly 2 while the base 104 transmits gripping force.
To accommodate tubulars or couplings of different diameters, the jaw assemblies 2 are rotated along cam surfaces 28 to retract the jaw assemblies 2 out of central bore 14. At the same time biasing means 94 makes contact with the cam surfaces 28 and causes end 90 of the dies 88 to protrude into a position where the largest clearance is created in bore 14, as described above with reference to the home position of the jaw assemblies 2.
In the foregoing specification, the invention has been described with a specific embodiment thereof; however, it will be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention.

6

Claims

1. A jaw assembly comprising:
a. a lever arm defining a lever arm pocket on a top surface thereof, said lever arm pocket having sides and a bottom face;
b. a cam roller moveable along a cam surface; and c. a die holder removably and pivotably received in the lever arm pocket and having a gripping surface for gripping the tubular, said die holder having sides and a base, wherein movement of the cam roller along the cam surface serves to pivot the die holder within the lever arm pocket.

2. The jaw assembly of claim 1, wherein the lever arm pocket further comprises one or more spring plungers biasing a first end and a second end of the die holder to protrude equally from the lever arm and into a central bore.

3. The jaw assembly of claim 2, wherein the lever arm further comprises a biasing means to pivot the die holder within the lever arm pocket and urge the second end of the die holder at least partially into the central bore when the jaw assembly is retracted.

4. The jaw assembly of claim 3, wherein the biasing means comprises a push rod protruding through the bottom surface of the lever arm pocket and forcible against the base of the die holder to urge the second end of the die holder towards the central bore and pivot the first end of the die holder out of the central bore.

5. The jaw assembly of claim 4, wherein the push rod is actuated by contact of the push rod with the cam surface when the jaw assembly is retracted.

6. The jaw assembly of claim 3, wherein movement of the jaw assembly from a retracted position to a tubular contacting position releases the biasing means and returns the die holder to a central position in which the first end and the second end of the die protrude equally from the lever arm.

7. The jaw assembly of claim 1, wherein pivoting of the base of the die holder in the bottom face of the lever arm pocket forms a first circular arc and pivoting of the sides of the die holder within the sides of the lever arm pocket form a second circular arc, wherein the first circular arc is concentric with the second circular arc.

8. The jaw assembly of claim 7, wherein contact between the sides of the die holder and the sides of the lever arm pocket is maintained during gripping and rotation of the tubular to absorb torque loads from the gripping surface through the die holder and to the lever arm.

9. The jaw assembly of claim 8, wherein contact between the base of the die holder and bottom face of the lever arm pocket is maintained during gripping of the tubular to transfer gripping load from the gripping surface through the die holder and to the lever arm.