Note: Descriptions are shown in the official language in which they were submitted.
CA 02621570 2008-02-12
POWER TONG
Field of the Invention
This invention relates to the field of devices for rotating tubular members so
as
to make up or break out threaded joints between. tubulars including casing,
drill pipe, drill
collars and tubing (herein referred to as pipe or drill pipe), and in
particular to a power tong for
the improved handling and efficient automation of such activity.
Background of the Invention
In applicant's experience, on conventional rotary rigs helpers, otherwise
known
as roughnecks, handle the lower end of the pipe when they are tripping it in
or out of the hole.
They also use large wrenches commonly referred to as tongs to screw or
unscrew, that is make
up or break out pipe. Applicant is aware that there are some other tongs that
are so called
power tongs, torque wrenches, or iron roughnecks wlaich replace the
conventional tongs. The
use of prior art conventional tongs is illustrated in Figure Ia. These other
tongs are described
in the following prior art descriptions.
In the prior art applicant is aware of United States Patent No. 6,082,225
which
issued February 17, 1997 to Richardson for a Power Tong Wrench. Richardson
describes an
power tong wrench having an open slot to accommodate a range of pipe diameters
capable of
making and breaking pipe threads and spinning in or out the threads and in
which hydraulic
power is supplied with a pump disposed within a rotary assembly, which pump is
powered
through a non-mechanical coupling, preferably magnetic, to a motor disposed
outside the
rotary assembly.
In the present invention the rotary hydraulic and electrical systems are
powered
at all times and in all rotary positions via the serpentine belt drive, unlike
Richardson
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#6,082,225 in which they are powered only in the home position. The pipe can
thus be gripped
and ungripped repeatedly in any rotary position with no dependence on stored
energy and the
unit can be more compact because of the reduced hydraulic accumulator
requirements for
energy storage (the present invention uses hydraulic accumulators for energy
storage only to
enhance gripping speed).
Applicant is also aware of United States Patent No. 5,167,173 which issued
December 1, 1992 to Pietras for a Tong. Pietras describes that tongs are used
in the drilling
industry for gripping and rotating pipes, stating that generally pipes are
gripped between one
or more passive jaws and one or more active jaws which are urged against the
pipe. He states
that normally the radial position of the jaws is fixed and consequently these
jaws and/or their
jaw holders must be changed to accommodate pipes of different diameters.
Applicant is also aware of United States Patent No. 6,776,070 which issued
August 17, 2004 to Mason et al. for an iron Roughneck. Mason et al. describes
an iron
roughneck as including a pair of upper jaws carrying pipe gripping dies for
gripping tool joints
where the jaws have recesses formed on each side of the pipe gripping dies to
receive spinning
rollers. By positioning the spinning rollers in the upper jaws at the same
level as the pipe
gripping dies the spinning rollers are able to engage the pipe closer to the
lower jaws and thus
can act on the tool joint rather than on the pipe stem.
Mason et al. describe that in running a string of drill pipe or other pipe
into or
out of a well, a combination torque wrench and spinning wrench are often used,
referred to as
"iron roughnecks". These devices combine torque and spinning wrenches and are
described in
U.S. Pat. No. 4,023,449, U.S. Pat. No. 4,348,920, and U.S. Pat. No. 4,765,401,
all to
Boyadjieff.
In the prior art iron roughnecks, spinning wrenches and torque wrenches are
commonly mounted together on a single carriage but are, nevertheless, separate
machines
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(with the exception of the prior art of Mason Patent 6,776,070 which combines
the spinner
wrench rollers and torque jaws in a common holder, nevertheless, they still
work independent
of each other). When breaking-out, or loosening, connections between two
joints of drill pipe,
the upper jaw of the torque wrench is used to clamp onto the end portion of an
upper joint of
pipe, and the lower jaw of the torque wrench clamps onto the end portion of
the lower joint of
pipe.
Drill pipe manufacturers add threaded components, called "tool joints", to
each
end of a joint of drill pipe. They add the threaded tool joints because the
metal wall of drill
pipe is not thick enough for threads to be cut into them. The tool joints are
welded over the end
portions of the drill pipe and give the pipe a characteristic bulge at each
end. One tool joint,
having female, or inside threads, is called a "box". The tool joint on the
other end has male, or
outside threads, and is called the "pin".
After clamping onto the tool joints, the upper and lower jaws are turned
relative
to each other to break the connection between the upper and lower tool joints.
The upper jaw is
then released while the lower jaw (back-up) remains clamped onto the lower
tool joint. A
spinning wrench, which is commonly separate from the torque wrench and mounted
higher up
on the carriage, engages the stem of the upper joint of drill pipe and spins
the upper joint of
drill pipe until it is disconnected from the lower joint. When making up
(connecting) two
joints of pipe the lower jaw (back-up) grips the lower tool joint, the upper
pipe is brought into
position, the spinning wrench (or in some cases a top drive) engages the upper
joint and spins
it in. The torque wrench upper jaws clamp the pipe and tightens the
connection.
Applicant is furtlaer aware of United States Published Patent Application
entitled Power Tong, which was published April 5, 2007 under Publication No.
US
2007/0074606 for the application of Halse. Halse discloses a power tong which
includes a
drive ring and at least one clamping device with the clarnping devices
arranged to grip a pipe
string. A driving mechanism is provided for rotation of the clamping device
about the
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longitudinal axis of the pipe string. The clamping device communicates with a
fluid supply
via a swivel ring that encircles the drive ring of the driving mechanism. Thus
Halse provides
for three hundred sixty degree continuous rotation combining a spinner with a
torque tong.
The Halse power tong does not include a radial opening, the tong having a
swivel coupling
surrounding the tong for transferring pressurized fluid from an external
source to the tong
when the tong rotates about the axis of the pipe. Halse states that having a
radial opening in a
power tong complicates the design of the power tong and weakens the structure
surrounding
the pipe considerably, stating that as a result, the structure must be up-
rated in order to
accommodate the relatively large forces being transferred between the power
tong and the pipe
string. Halse further opines that a relatively complicated mechanical device
is required to
close the radial opening when the power tong is in use, and in many cases also
to transfer
forces between the sides of the opening.
Summary of the Invention
The power tong according to the present invention continuously rotates
tubulars
for spinning and torquing threaded connections. Continuous rotation is
achieved through a
rotating jaw that grips the tubular and can continuously rotate it. Hydraulic
and electrical
power necessary for actuating the actuators or grippers must be generated on
board since the
continuous rotation does not allow for external connections, neither hydraulic
nor electrical
ones. A serpentine belt system turns the motors of the on board hydraulic
power unit and DC
generators to supply the gripper jaws with the necessary hydraulic and
electrical power.
The present invention includes a main drive, rotary jaw and back-up jaw, the
rotary jaw is supported and held into position by the use of opposed helical
pinions/gears
which support the rotary jaw vertically. The rotary jaw gripper cylinders are
held in position
by a linkage assembly that can withstand the torque parameters of the wrench
and the rotary
cylinders can be moved in a range of travel by an eccentric, this provides for
a tong that can
accommodate a large range of pipe diameters (3.5-in drillpipe to 9-5/8 in
casing). This large
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range can be accomplished without changing gripping jaws or jaw holders. The
tong does not
require a mechanical device to close the radial opening, nor does it need to
be upsized, the on-
board power source allows the new invention to be compact, can develop high
torque for
making and breaking and can spin at high speeds. The current invention also
overcomes the
limitation of the spinning wrench engaging the stem area of the drillpipe
(this will over time
cause fatigue in the stem area) as the spinning and torquing is accomplished
with the same jaw
that engages the pipe on the tool joint.
Brief Description of the Drawings
Figure 1 is, in exploded perspective view, the power tong according to one
embodiment of the present invention.
Figure l a is a depiction of the use of prior art conventional tongs.
Figure 2 is, in partially cut away view, the rotary drive section and
serpentine
drive belt of the power tong of Figure 1.
Figure 2a is a plan view of Figure 2.
Figure 3 is, in plan view, the power tong of Figure 1 in an assembled view.
Figure 4 is, in front elevation view, the power tong of Figure 3 with the
thread
compensator cylinders extended.
Figure 4a is, in side elevation view, the power tong of Figure 4 with the
thread
compensator cylinders retracted.
Figure 5 is a section view along line 5-5 in Figure 4.
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Figure 6 is a partially cut away section view along line 6-6 in Figure 4.
Figure 7 is a partially cut away view along line 7-7 in Figure 4.
Figure 8 is, in partially cut away perspective view, the back-up jaw section
of
the power tong of Figure 1.
Figure 9 is, in partially cut away plan view, the drive unit fixed stage of
Figure
8.
Detailed Desci~tion of Embodiments of the Invention
The power tong according to the present invention may be characterized in one
aspect as including three main sections mounted vertically one on top of the
other. Each of the
sections contains actuators as better described below. With the reference to
the drawings
which are not intending to be limiting, uppermost is the drive section 10
which includes speed
reduction unit 12, each including a number of motors, gearing coupling devices
and belts
enclosed in housings 14 as better described below, main drive hydraulic motors
16 and
serpentine drive hydraulic motors 18. Also included within drive section 10,
and although
shown exploded in Figure 1, is a serpentine belt drive 20 better described
below.
The second main section is the rotary jaw section 22, mounted below and
within the drive section 10 and above the back-up jaw section 24. The rotary
jaw section 22 is
cylindrical in shape with an opening slot 38 allowing the tong axis Z to be
selectively
positioned concentric with the pipe 8. The rotary jaw section 22 has three
gripper actuators
44a, 44b, and 44c arranged radially around axis Z and mounted between two
rotary jaw gears
30a and 30b.
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Serpentine belt 20 is driven by two serpentine drive hydraulic inotors 18 with
drive sprockets 26a, rotating serpentine belt 20 about the idler sprockets 26
which are mounted
on drive section 10 and six serpentine drive node sprockets 32 which are
double-grooved and
which are mounted on the rotary jaw section 22. The serpentine drive node
sprockets 32 are
comprised of two generator drive sprockets 32a and 32b, two pump drive
sprockets 32c and
32d and two rotary jaw idler sprockets 32e and 32f. In the illustrated
embodiment, the
generator drive sprockets, 32a and 32b, transmit rotary power to generators 34
and the pump
drive sprockets, 32c and 32d, transmit rotary power to hydraulic pumps 36 by
the action of
serpentine belt 20 engaging the upper groove of sprockets 32a, 32b, 32c and
32d. Three
synchronization belts, 28a, 28b, and 28c, connect the lower grooves of the
rotary-jaw double-
groove sprockets 32, specifically synchronization belt 28a connects pump drive
sprocket 32c
and generator drive sprocket 32a, synchronization belt 28b connects generator
drive sprocket
32b and rotary jaw idler sprocket 32e and synchronization belt 28c connects
rotary jaw idler
sprocket 32f and pump drive sprocket 32d. Thus as the rotary jaw section 22
rotates about
axis of rotation Z within a three hundred sixty degree rotational range of
motion about axis of
rotation Z, even though serpentine belt 20 on corresponding idler sprockets 26
cannot extend
across the opening slot 38 because it would restrict selective access of the
pipe, the serpentine
belt 20 wraps in a C-shape around the rotary jaw section 22 to provide for
continual contact
between serpentine belt 20 and a minimum of five of the rotary jaw sprockets
32. The
synchronization. belts 28 maintain rotation of the individual rotary-jaw
double-groove
sprockets 32 as they pass through the serpentine gap 29, that is the opening
between idler
pulleys 26a and 26b, and synchronize the speed and phase of the rotation of
rotary jaw drive
sprockets 32 to allow them to re-engage the serpentine belt 20 after passing
through the
serpentine gap 29. As an example, when the rotary jaw section 22 rotates in
direction B, pump
drive sprocket 32c will reach the serpentine gap 29 and the pump will then be
driven by
synchronization belt 28a rather than the serpentine belt 20. When rotation
continues such that
pump drive sprocket 32c passes beyond (farther counter-clockwise) idler
sprocket 26b then
pump drive sprocket 32c will re-engage with the serpentine belt 20. The
process repeats as
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each of the six rotary jaw drive sprockets 32 passes through the opening
between idler
sprockets 26a and 26b.
Idler 26d is spring-mounted to maintain minimum tension in the serpentine belt
20 regardless of the rotational position of the rotary jaw section 22. There
is a small variation
in the length of the path of the serpentine belt 20 as the rotary jaw section
22 rotates.
The sezpentine belt is preferably a toothed synchronous drive belt in order to
minimize belt tension requirements, to allow small sprocket diameters and to
avoid
dependence on friction which could be compromised by fluid contaminants.
The serpentine belt may be double-toothed (teeth on both sides) or single-
toothed with the teeth facing inward on the inside of the `C' and outward on
the outer side of
the `C' and with the serpentine drive motors 26 positioned outside the loop
and with two
additional idlers as shown in Figure YY. The serpentine drive may be split
into two or more
separate `C' sections as shown in Figure YY. A continuous synchronization belt
may be used
instead of the separate synchronization belts 28 as shown in Figure YY. A
roller chain could
alternately be used instead of the belt for the serpentine drive but would add
lubrication
requirernents, would be noisier and would have a lower life.
The number of serpentine drive nodes may be increased or decreased and the
number of idlers 26 may also vary.
An alternative serpentine system consists of split serpentine belt drive (as
opposed to a continuous belt as described above). This may require a different
arrangement of
sprockets and idlers.
Upper rotary jaw gear 30a and lower rotary jaw gear 30b are parallel and
spaced apart so as to carry therebetween hydraulic pumps 36, generators 34,
hydraulic tank 42,
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the rotary jaw hydraulic system 53, rotary jaw electrical controls 54 and the
set of three
radially disposed hydraulic gripper actuators 44a, 44b, and 44c, all of which
are mounted
between the upper and lower rotary jaw gears 30a and 30b for rotation as part
of rotary jaw
section 22 without the requirement of external power lines or hydraulic lines
or the like. Thus
all of these actuating accessories, which are not intended to be limiting, may
be carried in the
rotary jaw section 22 and powered via a nested transmission such as described
herein as
including serpentine belt 20, idler sprockets 26, one of which may act as a
belt tensioner,
synchronization belts 28 and serpentine drive node sprockets 32.
The serpentine belt 20 and paired drive pulley transmission is herein referred
to
generically as a form of nested transmission. Without intending to be
limiting, a nested
transmission may also include planetary gear seginents or other rigid,
flexible or resilient
iiiteracting rotational drive elements such as gears, belts, etc. wherein for
example, such as
with respect to the flexible serpentine belt 20, a circumferentially spaced
and radially spaced
apart array of rotational drive elements are mounted around one of the fixed
stages for
example the first or upper actuating stage so as to interact with a second set
of rotational drive
elements mounted on the rotating or second actuating stage and nested within
the
circumferential array of rotational drive elements mounted to the fixed stage.
The nested
transmission transfers power from the fixed stage to the rotational stage in a
continuous
fashion as, sequentially, one eleinent after another of the rotational drive
elements on the
rotating stage 'are rotated through and across the opening allowing selective
access of the
tubular 8. It is also equally intended herein that the use of a nested
transmission is intended to
also capture the reverse case where the rotatable drive elements mounted on
the rotating stage
are mounted around the outer circumference of the adjacent rotary jaw and
continuously
driven as the rotating stage is rotated by the rotatable drive elements which
are mounted on the
fixed stage nested inwardly of the drive elements on the rotating stage. These
and other nested
transmissions as would be known to one skilled in the art are intended to be
included herein so
long as the drive from the fixed stage to the rotating stage is substantially
continuous as the
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rotating stage rotates sequentially one after another of the rotatable drive
elements mounted on
the rotating stage across the opening into the yoke in which is mounted the
tubular.
In the preferred embodiment, the rotary jaw hydraulic system 53 is a dual
(high/low) pressure system or infinitely variable pressure system which
produces high
pressures (in the order of 10,000 psi) necessary for adequately gripping large
and heavy-duty
tubulars for applying make-up or break-out torque and lower pressures (5000
psi or less) to
avoid crushing. smaller or lighter-duty tubulars. Hydraulic pumps 36,
rotationally driven as
described above, are fixed-displacement, gear or piston pumps. In the idle
state, hydraulic
pumps 36 charge one or more gas-filled accumulators 55 mounted in or on the
rotary jaw
section 22 to store energy to enable rapid extension of the gripper actuators
44. In this way,
extremely fast gripping speeds can be achieved while keeping the power
transmitted by the
serpentine belt 20 drive very low,
Referring to the hydraulic schematic of Figure 10, unloading relief valve 58
acts as a safety pressure relief for the pumps and also unloads the flow from
the fixed-
displacement hydraulic pumps 36 to tank at low pressure when the
accumulator(s) are fully
charged (approximately 5000 psi). Return filter 60 cleans contaminants from
the hydraulic oil
as it returns to tank 42 and pressure filter 61 provides emergency filter
protection for the of the
system coinponents. Check valve 62 maintains pressure (approximately 5000 psi
fully
charged) in the accumulator(s) 55 even when the hydraulic pumps 36 are
unloaded to tank 42
at low pressure as desciibed above. Directional control valve 63 is a three-
position valve
which directs flow to either extend or retract the gripper actuators 44 or
hold them in any
intermediate position when the valve is unactuated. Directional control valve
63 is hydraulic
pilot actuated by pilot directional control valve 64 which is electric
solenoid actuated. Manual
directional control valve 65 functions the saine as directional control valve
63 described above
except it is manually actuated for emergency back-up in the event of
electrical failure or
during periods of deliberate shutdown of wireless communications (described
later) for
sensitive operations such. as perforating. Sequence valve 66 blocks flow to
the accumulator(s)
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when it is demanded by the grip circuit and includes a reverse-free-flow check
valve to allow
flow out of the accumulators at all times. Pressure reducing valve 67
regulates the grip
pressure according to the characteristics of the pipe connection, providing
high pressures
necessary for adequately gripping large and heavy-duty tubulars for applying
make-up or
break-out torque and lower pressures to avoid crushing smaller or lighter-duty
tubulars.
Pressure reducing valve 67 is remote-controlled by proportional pressure
relief valve 68 of
alternately by a discrete two or three step pressure control. Intensifier 69
boosts the grip
pressure by a factor of 4.3 (typical), providing a maximum grip pressure in
the order of 10,000
psi without the need for high-pressure pumps or valves. Shuttle valves 70
allow high flow
rates directly into the grip cylinders, by-passing intensifier 69, for rapid
extension of the
gripper cylinders to the point of contact with the pipe connection. Pressure-
compensated flow
control valves 71 equalize the rapid-advance flow between the cylinders for
centering
purposes, regardless of any load pressure variations.
The back-up jaw section 24 is typically mounted to a tong positioning system
(outside the scope of this invention) capable of holding the tong assembly
level and enabling
vertical and horizontal positioning travel. It could be pedestal-mounted on
the rig floor, mast-
mounted, track-mounted on the rig floor or free hanging froxn the mast
structure. The back-up
jaw section 24 includes a parallel spaced apart array of planar jaw frames and
in particular an
upper backup jaw plate 48a and a lower backup jaw plate 48b. Backup jaws
plates 48a and
48b may be maintained rigidly in their parallel spaced apart aspect by means
of thread
compensator cylinders 50. Apart from providing spacing between backup jaws
plates 48a and
48b, thread compensator cylinders 50 actuate so as to extend bolts 46 on rods
50a in direction
C so as to selectively adjust the spacing between the second actuating stage
22 and third
actuating stage 24. Thus with the cylindrical threaded joint 8eb of tubular 8
held within
cylinders 52a-52c in third actuating stage 24, and with the threaded tapered
female end or box
(not shown) extending upwardly from the tubular portion 8b held within
cylinders 52a-52c, as
the rotating or second actuating stage 22 is rotated relative to the fixed or
third actuating stage
24 so as to rotate tool joint pin 8c relative to tubular portion 8b, the
second and third actuating
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stages 22 and 24 respectively may be drawn towards one another by the
retraction of rods 50a
into cylinders 50 in direction C thereby threadably engaging threaded box 8c
onto the pin (not
shown). Cylinders 50 maintain a spacing which defines cavity between the
backup jaws in
which is rigidly mounted the array of radially spaced apart hydraulic
cylinders 52a, 52b and
52c. Hydraulic cylinders 52a-52c are radially spaced apart around axis of
rotation A and
disposed radially inwardly so that the operative ends of the actuators which
may be selectively
actuated telescopically into the distal end 40b of yoke 40 so as to clamp
therein a tubular 8 and
in particular a lower portion 8b of tubular 8 while an upper portion 8a of
tubular 8 is clamped
within cylinders 44a-44c and rotated in second actuating stage 22 in direction
B about axis of
rotation A relative to the fixed first and third actuating stages 10 and 24
respectively.
The rotary jaws 30a and 30b of seoond actuating stage 22 are maintained in
alignment interleaved between the first and third actuating stages 10 and 24
respectively by
means of guide rollers 54 which are rotatably mounted in a radially spaced
apart array
circumferentially around the outer circurnference of the rotary jaws and also
aligned
orthogonally relative to backup jaw 48a and parallel to one another, The
rotary jaw guide
rollers 54 centralize the rotary jaws preventing radial loading of the drive
pinions 56.
Interspersed circumferentially around the rotary jaws 30a and 30b are a
further radially spaced
apart parallel array of rotary jaw driving pinions 56 which interniesh and
engage helical teeth
56a with corresponding gear teeth on the outer circumference of rotary jaws
30a and 30b so
that as driving pinions 56 are driven by main drive hydraulic motors 16 via
reduction gear
system 58 rotary jaws 30a and 30b are simultaneously rotatably driven in
direction B about
axis of rotation A. Pinions 56 and gear teeth are helical to ensure proper
meshing thus even
torque splitting between top and bottom plates. All of the components in the
first and third
actuating stages are mounted on a frame 60.
As will be apparent to those skilled in the art in the ligbbt of the foregoing
disclosure, many alterations and inodifications are possible in the practice
of this invention
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without departing from the spirit. or scope thereof. Accordingly, the scope of
the invention is
to be construed in accordance with the substance defined by the following
claims.
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