U.S. patent application number 09/832764 was filed with the patent office on 2002-08-15 for replaceable tong die inserts for pipe tongs.
Invention is credited to Keyes, Robert C..
Application Number | 20020108748 09/832764 |
Document ID | / |
Family ID | 26891894 |
Filed Date | 2002-08-15 |
United States Patent
Application |
20020108748 |
Kind Code |
A1 |
Keyes, Robert C. |
August 15, 2002 |
Replaceable tong die inserts for pipe tongs
Abstract
A gripping assembly for pipe tongs is provided to grip and
rotate a pipe. The gripping assembly includes a pair of jaw
assemblies that exert counteracting forces on the pipe. Each jaw
assembly has a body with a cylindrical hollow defined in the body
and having longitudinal slots formed in the body. The slots are
separated from one another by longitudinal struts. In a cross
section perpendicular to the longitudinal direction of the
cylindrical hollow, flat faces of the slots form portions of a
regular polygon. Each jaw assembly also has toothed tong die
inserts that fit into the slots and provide for frictional
engagement of the jaw assembly with the pipe. Each jaw assembly
also has a first and a second end plate for retaining the tong dies
in the slots with at least one of the end plates being removably
attached to the body.
Inventors: |
Keyes, Robert C.; (Norman,
OK) |
Correspondence
Address: |
Bill D. McCarthy
Crowe & Dunlevy
1800 Mid America Tower
20 North Broadway
Oklahoma City
OK
73102
US
|
Family ID: |
26891894 |
Appl. No.: |
09/832764 |
Filed: |
April 11, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60196421 |
Apr 12, 2000 |
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Current U.S.
Class: |
166/77.51 ;
166/85.1 |
Current CPC
Class: |
E21B 19/161
20130101 |
Class at
Publication: |
166/77.51 ;
166/85.1 |
International
Class: |
E21B 019/18 |
Claims
What is claimed is:
1. A jaw assembly for pipe tongs with a rotation assembly housing,
the pipe tongs being a device for rotating a pipe, comprising: (a)
a body having a cylindrical hollow defined therein and having
longitudinal slots formed therein; (b) tong die inserts fitting
into the slots for providing frictional engagement of the jaw
assembly with the pipe; (c) first and second end plates normal to
the longitudinal direction to retain the tong dies inserts in the
slots; and (d) a base attached to the body and to the housing.
2. The jaw assembly of claim 1 wherein the slots are separated from
one another by struts that extend in a longitudinal direction of
the cylindrical hollow.
3. The jaw assembly of claim 1 wherein, in a cross section normal
to the longitudinal direction of the cylindrical hollow, flat faces
of the slots form portions of a regular polygon.
4. The jaw assembly of claim 1 wherein each of the slots have a
partial trapezoidal shape in a cross section normal to the
longitudinal direction of the cylindrical hollow.
5. The jaw assembly of claim 1 wherein the first end plate is
removably attached to the body.
6. The jaw assembly of claim 1 wherein the second end plate is
removably attached to the body.
7. The jaw assembly of claim 1 wherein the second end plate is
welded to the body.
8. The jaw assembly of claim 1 wherein the second end plate is
integrally formed with the body.
9. The jaw assembly of claim 1 wherein the tong die inserts are
substantially identical.
10. The jaw assembly of claim 1 wherein top faces of each tong die
insert are arcuate.
11. The jaw assembly of claim 10 wherein, when the tong die inserts
are positioned in the slots, the top faces of the tong die inserts
substantially define an arc of a circle.
12. The jaw assembly of claim 11 wherein a radius of the circle
defined by the top faces of the tong die inserts is substantially
the same as a radius of the pipe.
13. The jaw assembly of claim 12 wherein a bottom of each tong die
insert is flat.
14. The jaw assembly of claim 1 wherein there are at least three
slots.
15. A gripping assembly for pipe tongs that grip and rotate a pipe,
the gripping assembly comprising jaw assemblies for exerting
counteracting forces on the pipe, wherein each jaw assembly
comprises: (a) a body having a cylindrical hollow defined therein
and having longitudinal slots formed therein; (b) tong die inserts
fitting into the slots for providing frictional engagement of the
jaw assembly with the pipe; (c) first and second end plates normal
to the longitudinal direction to retain the tong die inserts in the
slots; and (d) a base attached to the body and to the housing.
16. The gripping assembly of claim 15 having two jaw assemblies
that exert opposed, counteracting forces on the pipe.
17. The gripping assembly of claim 16 further comprising a ram
corresponding to each jaw assembly to apply an inward force to each
corresponding jaw assembly.
18. The gripping assembly of claim 15 wherein at least one of the
first end plate and the second end plate of each jaw assembly is
removably attached to the body.
19. The gripping assembly of claim 15 wherein top faces of each
tong die insert are arcuate.
20. The gripping assembly of claim 19 wherein, when the tong die
inserts are positioned in the slots, the top faces of the tong die
inserts for each jaw assembly substantially define an arc of a
circle.
21. The gripping assembly of claim 20 wherein, for each jaw
assembly, a radius of the circle defined by the top faces of the
tong die inserts is substantially the same as a radius of the
pipe.
22. The gripping assembly of claim 21 wherein a bottom of each tong
die insert is flat.
23. The gripping assembly of claim 16 wherein the tong die inserts
are in contact with two-thirds of a circumference of the pipe.
24. A tong die insert for a gripping assembly for gripping a pipe,
comprising: (a) a flat bottom surface; and (b) an arcuate top
surface with a radius of curvature substantially equal to a radius
of the pipe.
Description
RELATED APPLICATIONS
[0001] The invention claims priority to U.S. Provisional
Application No. 60/196,421, filed Apr. 12, 2000.
FIELD OF THE INVENTION
[0002] The invention relates generally to pipe tongs for gripping
and rotating drilling pipe. More specifically, the invention
relates to a gripping assembly of the pipe tongs having replaceable
tong die inserts.
BACKGROUND
[0003] In handling a string of casing, drill pipe or tubing
(referred to interchangeably as pipe), workers connect several
segments of the pipe together. These segments of pipe commonly come
in thirty-foot lengths. A typical way to assemble the pipe segments
together is by a threaded pin and box connection. Several segments
of pipe assembled together are often referred to as a drill
string.
[0004] Workers use pipe tongs to thread or unthread pipe together
to form or take apart a drill string. Typically, workers grip a
first pipe segment while turning the second pipe segment with
respect to the stationary first pipe segment. The pipe tongs
perform two functions to assemble the pipe segments, namely
gripping and rotating selected pipe segments. Ideally, the tong
gripping mechanism, that often includes a tong die, slightly
penetrates the surface of the pipe in order to maintain a positive
grip on the pipe and to avoid crushing or permanently deforming the
pipe.
[0005] Pipe tongs were originally powered by hand and to some
degree still are. However, power tongs have replaced manual tongs
in many applications. Power tongs are especially useful when a
great deal of torque is needed to loosen a pipe connection.
[0006] Horizontal drilling, or directional drilling, is drilling in
the earth at some angle to the vertical direction. Horizontal
drilling is typically performed only when there is some obstacle to
vertical drilling because horizontal drilling is much more
expensive. With regard to pipe tongs, a worker performing
horizontal drilling has to be capable of operating the pipe tongs
at some angle to the vertical, sometimes at angles approaching
ninety degrees.
[0007] There have been many patents directed to the construction
and operation of pipe tongs and their components. For example, U.S.
Pat. No. 6,079,509 issued to Bee et al (Bee '509) discloses a die
set used in pipe tongs for gripping pipe while threadably coupling
pipe joints. The die set taught by Bee '509 uses two
semi-cylindrical pieces to grip a pipe. However, when a die set
wears out, one must either discard the die set or carry out
extensive machining to restore the gripping effectiveness of the
die set.
[0008] U.S. Pat. No. 6,047,775 issued to Mock (Mock '775) teaches a
pipe grip with two pairs of dies for loosening a drill pipe joint.
A problem with the dies of Mock '775 is that the top surfaces of
the dies are flat and therefore do not provide a precise, mating
engagement of the dies with the pipe. This can lead to slippage
between the pipe and the dies, which in turn can lead to mechanical
failure of the pipe.
[0009] Thus, there is a continuing need for an improved jaw
assembly for a gripping mechanism for pipe tongs that: (1) avoids
the problem of slippage; (2) can be maintained easily in an unworn
condition; (3) and is readily repairable when the gripping
mechanism becomes worn.
SUMMARY
[0010] The present invention provides a gripping assembly for pipe
tongs that grip and rotate a pipe. The pipe tongs are usable in
horizontal drilling applications. The gripping assembly includes a
pair of jaw assemblies that exert counteracting forces on the pipe.
The counteracting forces are applied by rams which are typically
hydraulically powered, but may also be electrically powered or
powered by hand.
[0011] Each jaw assembly has a body with a cylindrical hollow and
longitudinal slots separated by longitudinal struts. In a cross
section perpendicular to the longitudinal direction of the
cylindrical hollow, flat faces of the slots form portions of a
regular polygon. Each jaw assembly has toothed die inserts that fit
into the slots and provide for frictional engagement of the jaw
assembly with the pipe. The jaw assembly also has a first and a
second end plate for retaining the tong die inserts in the slots.
At least one of the end plates is removably attached to the body so
that the end plate may be removed, the tong die insert replaced,
and the end plate re-attached to the body.
[0012] It is therefore a principal object of the invention to
provide a gripping assembly for a pipe having replaceable tong die
inserts.
[0013] Other objects, features and advantages which characterize
the present invention will be apparent from the following detailed
description and a review of the associated drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a perspective view of a jaw assembly for pipe
tongs of the existing art.
[0015] FIG. 2 is a front view of a gripping assembly of the present
invention.
[0016] FIG. 3 is an isometric view of a jaw assembly for pipe tongs
of the present invention.
[0017] FIG. 4 is a front view of a jaw assembly for pipe tongs of
the present invention.
[0018] FIG. 5 is a side view of a jaw assembly for pipe tongs of
the present invention.
[0019] FIG. 6 is a front view of a toothed insert that fits in a
jaw assembly for pipe tongs of the present invention.
DESCRIPTION
[0020] Before discussing the present invention, it is useful to
first consider a die of the existing art, as shown in FIG. 1. The
die shown in FIG. 1 is part of a die set that grips a pipe in a
tong assembly. However, it is easily seen that, if the die of FIG.
1 loses gripping effectiveness, it requires extensive machining to
restore this gripping effectiveness. Furthermore, it is very
expensive just to discard the entire die simply because the
gripping surface of the die has worn. Thus, it is apparent that it
would be much more cost-effective to have a replaceable gripping
surface for the die.
[0021] Turning now to an embodiment of the present invention shown
in FIG. 2, a gripping assembly 10 is positioned inside a housing
(not shown) of either a rotation assembly or an assembly for
holding a pipe 12 stationary. The gripping assembly 10 has two
opposed jaw assemblies 14A and 14B. Each jaw assembly 14A (or 14B)
has a base 16A (or 16B) connected to a ram 18A (or 18B) by placing
a connecting pin 20A (or 20B) into connection hole 22A (or 22B) in
the base 16A (or 16B). The ram 18A (or 18B) exerts an inward force
on the jaw assemblies 14A (or 14B), which in turn exert opposed,
gripping forces on the pipe 12. The ram 18A (or 18B) may be powered
by a hydraulic system, by an electric motor system, by hand or any
equivalent device.
[0022] In FIGS. 3-5, a single embodiment is shown of a jaw assembly
14 for a gripping assembly 10 of the present invention. In FIG. 3,
the jaw assembly 14 has a body 24 with a cylindrical hollow 26
defined within the body 24. The cylindrical hollow 26 has the shape
of a polyhedral cylinder, but will hereafter be referred to as
simply cylindrical.
[0023] The body 24 also has longitudinal slots 28 formed within the
body 24. Toothed tong die inserts 30 fit into the longitudinal
slots 28. Teeth 32 of the tong die inserts 30 provide frictional
resistance when a pipe is positioned between opposed jaw assemblies
14A and 14B, as shown in FIG. 2. This frictional resistance is
critically important for the pipe tongs to grip the pipe 12 when
assembling or taking apart a drill string.
[0024] A cross section of any one the slots 28 is generally
trapezoidal or dove-tailed in shape, with a top boundary of each
slot 28 being open. This cross-sectional shape for the slots 28
naturally retains the tong die insert 30 within the slot 28 in
reaction to any force that would tend to dislodge the tong die
insert 30 from the slot 28. Faces 34 of the slots 28 are flat and
discontinuously form, in a cross section, an incomplete portion of
a regular polygon.
[0025] It is important that the face 34 of the slot 28 is flat to
permit easy sliding of the inserts 30 into the slots 28. This is
particularly important for in-the-field replacement of the inserts
30 where the inserts 30 must be changed very quickly. The slots 28
are separated from one another by struts 36 that extend in the
longitudinal direction of the cylindrical hollow 16.
[0026] A first end plate 38 and a second end plate 40 retain the
inserts 30 in the slots 28. The first end plate 38 is removably
attached to the body 24 with bolts 42. The bolts 42 screw into
threaded bolt holes 44 in the body 24. The second end plate 40 is
welded to the body 24. The end plates 38 and 40 are especially
important for horizontal drilling. For vertical drilling, only a
lower support end plate would be needed because gravity would keep
the inserts from being dislodged from the upper end of the jaw
assembly.
[0027] It is important that one of the first end plate 38 or the
second end plate 40 be removably attached to the body 24. This
permits one to temporarily remove the removable end plate, slide
out an insert 30 after the teeth 32 have been worn down, put in a
new insert 30, replace the end plate 38 or 40, and resume operation
of the tongs. Connection hole 22 is formed in the base 16 for
connecting the body 24 to a ram (shown in FIG. 2).
[0028] It should be noted that the end plates 38A and 38B shown in
FIG. 2 has a slightly different geometry than the end plate 38
shown in FIG. 3. The end plates shown in FIG. 2 have a partial
polygonal void defined in the plates 38A and 38B, while the end
plate 38 shown in FIG. 3 has a partial circular void defined in the
plate 38.
[0029] In FIG. 4, the jaw assembly 14 has a body 24 with a
cylindrical hollow 26 defined within body. The body 24 also has
longitudinal slots 28 formed within the body 24. Tong die inserts
30 (not shown in FIG. 4) fit into the longitudinal slots 28.
[0030] A cross section of any one the slots 28 is generally
trapezoidal or dove-tailed in shape, with a top boundary of the
slots 28 open. This cross-sectional shape for the slots 28
naturally retains the insert 30 within the slot 28 in reaction to
any force that would tend to dislodge the tong die insert 30 from
the slot 28. Faces 34 of the slots 28 are flat and discontinuously
form an incomplete portion of a regular polygon.
[0031] It is important that the face 34 of the slot 28 is flat to
permit easy sliding of the inserts 30 into the slots 28. This is
particularly important for in-the-field replacement of the inserts
30 where the inserts 30 may need to be changed very quickly. The
slots 28 are separated from one another by struts 36 that extend in
the longitudinal direction of the cylindrical hollow 26.
[0032] A first end plate 38 and a second end plate 40 retain the
inserts 30 in the slots 28. The first end plate 38 is not visible
in the cross section shown in FIG. 4. The first end plate 38 is
removably attached to the body 24 with bolts 42. The bolts are not
visible in the cross section shown in FIG. 4. The bolts 42 screw
into threaded bolt holes 44 in the body 24. Connection hole 22 is
formed in the base 16 for connecting the body 24 to a ram 18(not
shown).
[0033] In FIG. 5, the jaw assembly 14 has a body 24 with slots 28
(not visible) defined in the body 24. Tong die inserts 30 (not
visible in FIG. 5) fit into the slots 28. A first end plate 38 and
a second end plate 40 retain the inserts 30 in the slots 28. The
first end plate 38 is removably attached to the body 24 with bolts
42. The bolts 42 screw into threaded bolt holes 44 in the body 24.
The second end plate 40 is welded to the body 24. Connection hole
22 is formed in the base 16 for connecting the body 24 to a ram 18
(not shown).
[0034] In FIG. 6, an embodiment of a tong die insert 2304 is shown
with a top face 46 that is arcuate. The top faces 46 of the inserts
30, when positioned in the slots 28, define an arc of a circle. The
radius of the circle so defined substantially matches the radius of
the pipe 12 being held in the jaw assembly 14. A bottom 48 of the
tong die inserts 30 is flat to match the flat faces 34 of the slots
28.
[0035] For all embodiments of the present invention, it is also an
important feature that at least three slots be formed in the body
of the jaw assemblies. This permits the tong die inserts 30 to
sufficiently encompass the circumference of the pipe 12 without
having to use more than two jaw assemblies. Using more than two jaw
assemblies greatly increases the cost of the gripping assembly. The
combination of using (1) two jaw assemblies with (2) at least three
slots 28 for each jaw assembly is a combination that provides an
effective balance of gripping ability and cost effectiveness. For
the particular embodiment shown in FIG. 2, the two jaw assemblies
together encircle approximately two-thirds of the pipe.
[0036] In accordance with the foregoing description, a gripping
assembly for pipe tongs is provided to grip and rotate a pipe. The
gripping assembly includes a pair of jaw assemblies that exert
counteracting forces on the pipe. The rams that are typically
hydraulically powered. Each jaw assembly has a body with a
cylindrical hollow defined in the body and having longitudinal
slots formed in the body. The slots are separated from one another
by longitudinal struts. In a cross section perpendicular to the
longitudinal direction of the cylindrical hollow, the flat faces of
the slots form portions of a regular polygon.
[0037] The jaw assembly also has toothed tong die inserts that fit
into the slots and provide for frictional engagement of the jaw
assembly with the pipe. Each of the slots has a trapezoidal shape
that naturally retains the tong die insert in the slot in response
to any force that would otherwise dislodge the tong die insert. The
jaw assembly also has a first and a second end plate for retaining
the tong dies in the slots. At least one of the end plates is
removably attached to the body so the removable plate may be
temporarily removed, the tong die insert replaced, and the
removable end plate put back in place. Each of the tong die inserts
has an arcuate top face and a flat bottom. When placed in the
slots, the top faces of the inserts define a circle that has
substantially the same radius as the radius of the pipe that is
held between the jaw assemblies. A base of the jaw assembly
connects the body of the jaw assembly with the ram.
[0038] Although the present invention has been described with
respect to the embodiments shown in the drawings, those skilled in
the art would appreciate that additions, deletions, modifications
and substitutions may be made without departing from the spirit and
scope of the invention as defined by the claims below.
* * * * *