Note: Descriptions are shown in the official language in which they were submitted.
aye
TONG ASSEMBLY
Field no the Invention
This invention relates to power tongs of the type
used to make up and break out tool joints in oil field
drilling applications, and more particularly provides an
interconnected power tong and backup tong assembly.
Background of the Invention
Numerous tong assemblies exist which are
effective to make up and break out a threaded tool joint.
However, many of these tongs are complex in design and
operation and/or limited with respect to the size range of
drill pipe which can be accommo~atea. Some tongs grip a tool
joint at only two locations, increasing the potential for
slipping of the joint from the grip of the jaw dies, and for
wear of the dies, as well as the potential for over stressing
of the tool joint. Other tongs alleviate these limitations
through the use of three or more movable jaws and associated
gripping dies. Exemplary of this type of tong is that
described in U. S. Patent No. 4,û05,621, assigned to the
assignee of the instant invention, which teaches the
simultaneous gemming engagement of preferably three jaw dies
with a tool joint whereby equal forces are applied to the
joint. The patent also teaches a backup tong suspended from
a power tong, the backup tong requiring inversion for the
respective makeup or wreak down operation. The power tong
and backup tong described in the patent, as with all known
tongs, is designed such that during operation the tool joint
is positioned with its central axis along the longitudinal
384~
axis of the tongs. The tool joint is centered in the primary
openings surrounding the tool joint during operation.
It is desirable to provide a tong assembly,
including an interconnected power tong and backup tong,
wherein the backup tong effectively contacts a tool joint at
at least three points, and which allows makeup and break out
without inverting the backup tong.
This invention provides a tong assembly which
allows three point contact of a backup tong with the tool
joint through single point contact of a jaw. The tong
assembly is relatively simple in construction and operation,
and operates without inversion of the backup tong. And,
during operation the longitudinal centerline of the backup
tool is displaced from the central axis of the tool joint.
- According to the present invention there is
provided a tong assembly for makeup and break down of a
threaded tubular tool joint having an upper section, a lower
section and a central axis. The assembly has a power tong
with a longitudinal axis and means for gripping, rotating and
positioning the upper section of the tool joint with the
central axis of the tool joint aligned with the longitudinal
axis of the power tong. A backup tong is positioned below
the power tong, the backup tong having a longitudinal axis, a
bushing including a rear surface and two side surfaces, a
first die having first teeth and first means for engaging the
first die teeth with the lower section of the tool joint such
that upon application of torque by the power tong to rotate
- 2 -I
oh
~L2~88~8
the upper section in one direction the backup tong moves
through a limited rotation relative to the power tong and the
lower section is fixedly retained among the first die teeth,
the rear surface and one of the side surfaces, and is
positioned with the central axis of the tool joint at a first
position spaced to one side of the longitudinal axis of the
backup tong. The backup tong also has a second die having
second teeth and second means for engaging the second die
teeth with the lower section of the tool joint such that upon
application of torque by the power tong to rotate the upper
section in the opposite direction the backup tong moves
through a limited rotation relative to the power tong and the
lower section is fixedly retained among the second die teeth,
the rear surface and the other one of the side surfaces, and
is positioned with the central axis of the tool joint at a
second position spaced to the other side of the longitudinal
axis of the backup tong. Means are provided for inter-
connecting the power tong and backup tong and for supporting
one from the other, the interconnection means allowing the
limited rotations of the backup tong, in a plane
perpendicular to the central axis of the tool joint, relative
to the power tong.
In a specific form a power tong of conventional
design, for example as disclosed in the above-discussed US.
patent, is interconnected with a backup tong, the power and
backup tong each having a forward opening for receiving a
tool joint. The backup tong is positioned beneath the power
- pa
oh
~LXZ13~348
tong, and is generally parallel thereto, so that both are in
a horizontal plane during operation on vertically extending
pipe and tubing joints. Terms used throughout this
disclosure such as "upper" or "lower" refer to the position
of a component with the tongs in the horizontal plane. A
pair of elongated support arms extend from the rearward
portion of the power tong to the forward portion of the
backup tong. The arms are preferably kinked and sufficiently
- 2b -
kh/jc
8~3
flexible to allow limited lateral displacement no rnta~ion
of the backup tong in a horizontal plane relative to the
power tong. Toe power and backup tongs are also affixed at
their rearward portions through a pin-and-slot connection
alloying relative forward and rearward motion between the
power and backup tongs. On extension at the rear of Ike
backup tong has a square cross section which Lo loosely
contained within a square opening of a gusset fixedly
attached to the power tong to further allow displacr-r,lenL an
particularly limited rotation.
The backup tong receives the tool joint to be
gripped within a channel shaped replaceable bushing havinlJ
two parallel size surfaces at right angles to a rear
surface. The dimension across the side surfaces of the
bushing is larger than the outside diameter of any tool joint
which will be gripped. The bushing also induces a winnow
between its upper and lower surfaces which allows entry into
the interior of the channel my a free gemming jaw with a die
having gripping teeth. The far end of the jaw is also formed
as a gear inter meshing with a power gear driven by a
hydraulic piston in a cylinder pivotal pinned to the backup
tong. These power train components are supported between an
upper and lower plate assembly.
Two power trains, each including a free jaw, may be
mounted to thy backup tong, one being used during makeup of
the joint and the other being used during break down. The
jaws are each configured as a cam and, as described more
fully hereinafter, are self energizing to seat firmly in
~2288~3
position against the bottom pipe of a tool joint during a
gripping operation.
fixed to the rear of the backup tong is a
pivot able stiff arm, extendible an retractable during motion
of the backup tong onto and off of the tool joint, and during
limited rotation of the backup tong relative to the power
tong. The stiff arm is connected to the rear of the backup
tong through a dual pin, universal type hinge. The stiff arm
is pivoted by a hydraulic cylinder and includes a connection
allowing free extension and retraction through a telescoping
connection between two cylindrical tubes.
It has been discovered that operation of prior
tongs is dependent upon the degree to which the longitudinal
centerlines of the power tong and backup tong are maintained
coincident with the central axis of the tool joint, and also
each other. More coincident positioning of these axes is
desirable as it results in smoother operation of the tong
assembly.
In operation of the tong assembly disclosed
herein, the forward openings of the power tong and backup
tong are slipped about the tool joint such that the upper
pipe can be gripped by the power tong and the lower pipe can
be gripped by the backup tong. The tool joint is then
gripped by the jaws of` the power tong in conventional manner,
the central axis of the tubes being positioned along the
longitudinal axis of the tong. However, in contradistinction
to the prior art, the backup tong is moved into position
whereby the central axis of the pipes is displaced laterally
_~_
~22l384~3
from the longitudinal centerline of the backup ton. The
tool joint is positioned in the corner of the bushing such
that the joint is contacted by the rear surface and one side
surface at approximately 90, and a third firm point of
contact is subsequently established by the die teeth of the
gemming free jaw. The lateral deflection of the support arms
allow the backup tong to I displaced off center with respect
to the power tong.
To, for example, make up a threaded connection,
the upper pipe is rotated by the power tong and the lower
pipe is retained in place by the three point contact of the
backup tong. As the torque from the power tong increases,
the lower pipe has a tendency to slip minimally in the
bushing. However, the gripping force of the gemming free jaw
increases upon the minimal slippage, until a point at which
the gemming free jaw, and lower pipe, are fixed in position
by this so termed self-energizing action. At this point
continued application of torque to the joint is resisted in
the backup tong housing by forces flowing between the gemming
free jaw and the bushing. The reactive force at the pivotal
connection tends to rotate the entire backup tong about the
point of contact of the gemming jaw and the lower pipe. This
relative rotation between the power tong and backup tong is
accommodated by the support arms.
Breakout of a joint is substantially similar to
the makeup operation, except that the tool joint is supported
on the opposite corner of the rushing and a second kimono
122~384~3
jaw, extending into the bushing from the opposite side of -the
tong, is utilized to contact and grip the lower pipe.
Brief Description of the Drawings
The advantages, nature and additional features of
the invention will become more apparent from the following
description, taken in connection with the accompanying
drawings, in which:
Figure 1 is a simplified top view of selected
components of a backup tong in accordance with the invention;
Figure 2 is a simplified side view of the backup
tong of Figure l;
Figure 3 is a perspective view of a replaceable
bushing in accordance with the invention;
Figure 4 is a top view, partially in section, of
a free jaw;
Figures 5 and 6 are respectively a side and front
view of a die position able on the free jaw of Figure 6;
Figure 7 is a plan view of a power gear;
Figures 8, 9 and 10 are respectively a bottom,
front and partial side view of a housing weldment of a cup
tong in accordance with the invention; and
Figure 11 is a simplified plan view, partially in
section of a stiff arm and backup tong in accordance with the
invention.
Description of the referred Embodiments
Referring now to Figures 1 and 2 there is shown a
tong assembly 2û including a backup tong 22 mounted beneath a
power tong 24. The interconnection between the power and
--6--
~L~288~8
backup tongs allows limited relative movement between the
power and backup tongs. Ire specifically, a pinner connection
26 allows forward and rearward sliding of the backup and power
tongs relative to one another. At the region of the pinned
connection, as shown best in Figure 2, an extension 112 of
the backup tong having a square channel cross section is
supported within a larger square opening 113. The squares
are arranged with parallel sides and this interconnection
allows a limited rotation of several degrees between the power
lo and backup tongs in a plane perpendicular to the central axis
of the tool joint. A pair of support arms 28 are affixed
to the rearward portion of the power tong 24, such as by motion-
teal fasteners or integral welding, and extend downwardly
and forwardly for connection with clips 30 toward the forward
end of the backup tong 22. The clips 30 include means for
leveling the backup tong 22 relative to the power tong 24,
such as a screw adjuster 33. The support arms 28 are suffix
ciently flexible to allow lateral offset, particularly at
the forward portion, between the power tong 24 and backup
tong 22, as well as a limited rotation of the backup tong
22 relative to the power tong 24 in a horizontal plane.
As used throughout this disclosure and the appended
claims, "lateral" refers to a direction normal to a long-
tudinal axis of the power or backup tong, the longitudinal
axis of the backup tong being identified in Figure l by the
reference numeral 32 applied to the longitudinal centerline
of the backup tong. "Forward" refers to the end of the
power or backup tong which has an opening
-- 7 --
mob
~2F~848
to receive a wont< piece such as a pipe, tubular member or
tool joint 34. The axis of the tubular workups is referred
to as a central axis (c) an is described as being vertically
positioned
The backup tong 22 has an opening 36 which can be
moved into a position about the tool joint 34. Positioned
within the opening 36 is a replaceable positioning Dusking
38. Affixed to the bushing 38 are attachment lugs 40
(Figures 1 and 3) which are mounted to mating lugs 42
(Figures 1 and 8) on a housing 44 of the backup tong 22 by an
attachment bolt 46. The rushing 38 forms a channel shaped
interior area 48. The interior of the bushing is former
between a flat rear surface 50 and two flat side surfaces 52,
54. The side surfaces are generally parallel to each other
and normal to the rear surface. The side and rear surfaces
are hard surfaced to allow the tool joint 34 to rotate
slightly under extreme forces without galling of the joint 34
or the bushing 38. A window 56 is formed in the bushing 38
to allow passage of a free jaw 58 and die 60 subassembly into
and out of the interior area 48.
The replaceable die 6û (Figures 1, 5 and I) is
seated within a cutout 62 of the free jaw 58 (Figures 1 and
4) and is held in position by a bolt (not shown) aligned
through a passage 64 in the jaw 58 and a slot 66 in the die
60. The die 60 has teeth 68 which contact and engage the
lower pipe of the tool joint 34. The free jaw 58 pivots
about a pin 70 which passes through an opening 72 in the free
l~X8~348
jaw. The jaw also includes gear teeth 74 which intermesh
with a power gear 76.
The power gear 76 (Figures 1 and 7) pivots about
a pin 78 passing through an opening 80. The power gear has
teeth 82 which mesh with the teeth 74 of the free jaw. An
end of the power gear opposite the gear teeth 82 is pivotal
affixed to a piston rod 84 through a pin 86 passing through
openings 88 in two ears 90 of the gear 76.
The piston rod 84 extends from a cylinder 92.
The cylinder 92 is pivotal pinned for rotation about a pin
94 affixed to the housing 44. Tune cylinder Ye includes a
port 96 for insetting and out letting a driving fluid,
preferably hydraulic, into the cylinder behind a piston ring
98. A similar port 100 passes a fluid to and from the region
in front of the piston ring 98.
The components in Figure 1 form a triangle
between the center of the pivot pin I (point b), the
elongated central axis of the tubing joint (point c), and the
point of contact between the free jaw and tubing joint (point
a). The self energizing grip is a result of the length be
always being smaller than the sum of the lengths be plus act
In the fully engaged orientation, it has been found that the
tong assembly operates well when the cam angle, ankle arc, is
between approximately three (~) degrees and seven (7)
degrees. At larger angles the free jaw and die tend to slip
away from the tubing joint upon application of torque the
self energizing action is lessened. At smaller angles,
loading throughout the backup tong is higher than otherwise
go _
~2~34~
desirable; high loads are placed on the pin 72, on the die
teeth, and a larger spreading force is placed across the
opening I
A single power train including the cylinder 92,
piston rod 84, power gear 76 and free jaw 58 is shown fully
in Figure 1. A second similar train, exemplified at
reference numeral 99, is positioned on the opposite side of
the housing as a mirror image of the first described train.
Similarly, lugs 40, 42 for attachment of the bushing 38 are
also positioned on the opposite side of the housing.
The housing 44 of the backup tong is, in
conventional manner, comprised of a bottom plate assembly 10
and a top plate assembly lû4, shown best in Figures 9 and
I The free jaw 58, power gear, piston rod 84 and cylinder
I are disposed between eye plate assemblies lG2, 104. The
slate assemblies 102, lû4 are separated by vertical supports
106 and side plates 108. The clips 30 are affixed to the
side plates 108. The frontal region of the weldment an the
backup tong 22 is open to allow for motion of the free jaw
58. Also shown in Figure 9 are the housing lugs 42 which
extend downwardly from the bottom plate assembly 102. The
extension 112 at the rear of the backup tong 22 is shape in
cross section as a square channel, and fits loosely within
the square opening 113 (Fig. 2). sliding forward and rearward
motion between the backup and power tongs can be accomplished
by sliding along the square extension 112.
Additionally shown on Figure 8 are front legs 114
. and a rear leg 116. These legs 114, 116 are utilized when
so - -
aye
the tony assembly I is Lucy nun a floor. the legs extent
below the lugs 42 to protect the lugs from damage. At the
forward end of the housing 44 wel~ment are shown a latch lug
118 and a hinge pin opening 12û. The hinge pin opening 120
receives a hinge pin for pivotal attachment of a closure door
119 as well known. The door 119 is latches to the latch lug
118 in the closed position and ages rigidity to the backup
tong to prevent the opening 36 from spreading upon the
application of torque to the tool joint. Three square posts
122 add further rigidity to the housing 44. At the rearward
portion of the housing 44 is a gusset 124 which adds
structural support to the backup tong and particularly the
region of connection of the extension 112.
Referring now to Figure 11, there is shown a
stiff arm 126 intPrcGnr,ec~-o to the Dac~up ton I Thea 2
double hinge 128. Affixed to the stiff arm 126 is a fluid
operated, preferably hydraulic, drive piston and cylinder
130. Both the drive cylinder 13U an the stiff arm 126 are
pivotal affixed to the drilling rig on which the tong is
used through respective pivot holes 132 and 134. The stiff
arm 126 is comprised of an internal tube 136 telescopinyly
positioned within an external tube 138. A bar 140 extends
through slots 142 in the internal tube 13~. Springs 14~ an
146 bias the internal 136 and external 138 tubes toward a
preselected position.
Operation of the tong assembly 20 during joint
makeup will now be describeLi. The tong assembly is moved
into a position whereby the elevation of the gripping
, .
--11--
:lZ~88~8
structure of the power tong 24 allows the power tong to grip
the upper tube. The die teeth of the free jaw of the backup
tong are at an elevation to contact the lower tube. The tong
assembly 20 is then moved to a position so that the opening
36 of the backup tong and a similar opening of the power tong
is positioned about the tool joint 34. The stiff arm is
connected to the backup tong and actuated such that the tong
assembly is placed about the tool joint and the tool joint is
positioned against the bushing rear surface 50. This
movement involves extension of the drive piston an cylinder
130.
The backup tong is then actuated such that, as
viewed in Figure 1, the piston rod 84 is retracted into the
cylinder 92, pivoting the power gear 76 clockwise and the
free jaw 58 counterclockwise. The movement of the free jaw
continues until the die 60 contacts the tool joint 34. The
power tong 24 is then actuated so that the gripping dies or
other structures engage the tool joint 34 so that the
longitudinal axis of the power tong, identified by reference
numeral 148 in Figure 1, is aligned with the elongated
central axis c of the tool joint 34. Stated in other terms,
the power tong 24 is positioned so that the axis c of the
tool joint 34 is coincident with the center point between the
gripping dies no the power tong 24. The rotational movement
of the tool joint which is created by the power tong,
positions the tool joint against the side surface I of the
replaceable bushing. In this position, the axis c of the
tool joint is offset from the longitudinal axis 32 of the
-12-
backup tong by a distance I. Stated in other terms, the
longitudinal axis 32 of the backup tong is displaced
laterally, at the central axis of the tool joint, a distance
d with respect to the longitudinal axis of the power tong.
The power tong rotates the upper tube of the tool
joint clockwise and, as additional torque is applied, the
lower tube rotates a slight amount in a clockwise rotation.
This slight clockwise rotation is limited by the self
energizing setting of the die teeth 68 in the tool joint 34
wall. Thus, it will be noted that the gemmed contour and
positioning of the jaw 58 and die 60 is such that
counterclockwise rotation of the free jaw, corresponding to
clockwise rotation of the tubing, self energizes the contact
since the distance from the pivot pin 70 to a point on the
die teeth increases as the point moves clockwise along the
die teeth. In this sense the jaw Behaves with a gemming
action. The hard surface finish of the bushing 38 allows the
minimal rotation without galling of the tubing or bushing.
Continued application of torque to the upper tube
in a clockwise rotation is resisted by a corresponding
restraining torque in the lower tube in a counterclockwise
direction f. The free jaw acts to restrain the torque in the
lower tube by a correspnndiny reaction torque if in a
counterclockwise direction. These forces are transferred to
the housing through the pin 72 and the replaceable bushing
38. The backup tong tends to rotate in a clockwise direction
with respect to the power tong upon the continue application
of torque to the upper tube to make up the tool joint.
-13-
~;:28~348
Rotation is restrained to approximately three (3) degrees
with the power tong socket type square channel interconnection
to the backup tong extension 112.
When the power tong has tongued the tool joint
a preselected amount, the rotation is reversed to release
the power tong grip on the upper member of the tool joint.
To remove the backup tong from the lower member of the tool
joint, the piston rod 84 is extended outwardly from the cylinder
92. This is accomplished by application of fluid pressure
through port 96 to the rear of the piston ring 98, causing
a force f3 acting on the piston ring and a resulting force
f4 acting on the cylinder pin 94. The force f3 is transmitted
to the power gear 76 causing rotation in a counterclockwise
direction identified as f2 in Figure 1. The power gear 76
transmits the force f2 to the free jaw 58 through the inter-
meshing gear teeth. Motion of the free jaw is resisted by
the penetration of the die teeth 68 in the tool joint. The
lower member of the tool joint is fixed by forces external
to the tool assembly such as those applied by a slip in a
drilling table floor or merely the extreme weight of a long
drilling string. As the interconnection between the backup
and power tongs at the rear of the tong assembly is comprised
of the square channel in a larger square opening, allowing
limited relative rotation on the order of three degrees, the
forces rotate the power tong in a counterclockwise direction.
The stiff arm 138 will then extend or retract allowing counter-
clockwise rotation of the backup tong and power tong assembly
for an amount sufficient to free the die penetration from the tool
mob/ I,
34~
joint. The gemming free jaw will then move to the disengage
retracted position within the backup tong housing, shown in
phantom in Figure 1, as the piston extends to its full
forward position.
A breakout operation is generally the reverse of
the makeup operation. The second gripping train 99 including
a free jaw, power gear and piston and cylinder is utilized
and the lower tubing of the tool joint is positioned and
gripped in the opposite corner of the bushing against the
lo rear surface I and the side surface 54. The forces
generated upon actuation of the power tong to break out the
joint through counterclockwise rotation of the upper tune
result in a counterclockwise rotation of the backup tong
relative to the power tong.
The disclosed tong assembly provides effective
gripping of a tool joint for makeup and wreak out
operations. A single gripping die is used during a given
makeup or breakout sequence. Use does not require centering
or longitudinal alignment of the power and backup tongs with
respect to the tool joint and each other, providing greater
operational flexibility than previously obtainable.
Additionally, the backup tong can accommodate a relatively
larger range of tool joint diameters with a given bushing as
well as further expansion of that range through use of
replaceable bushings. It will be apparent that many
modifications and additions of the disclosed tong assembly
are possible. It therefore is to be understood that the
-15-
aye
description and Figures are intended to be taken as
exemplary, and not in a limiting sense.
