Note: Descriptions are shown in the official language in which they were submitted.
~~~P'
~1~:~.~l~r~~~i,c~ ~.r~ ~r1'~, ~.,~,~ J,,a,~~ za,ny;~ ~r,~~~~~c~ ~~~~~i~~
CA 02354297 2001-09-11
F&K 1086-02-02
- Page 1 -
and in particular such tongs for rotating pipe having a
variety of diameters.
BACKGROUND
Power tongs are common in well drilling operations for
rotating cylindrical drill pipe, casing and the like to
thread lengths together. Such tongs can have a closed
throat, such that the pipe must enter the tongs through the
hole in the middle, or can have an open throat, allowing
the pipe to enter the tongs from the side.
Both types of tongs typically include top and bottom tong
plates that are fastened together to form a tong housing
with a central housing aperture. An open throat may lead
to the central housing aperture, and typically a door will
be provided to close the throat on the housing. A drive
mechanism is mounted in the tong housing and rotates a ring
gear. In open throat tongs, where the ring gear has an
open throat leading to a central ring aperture, the drive
typically comprises a drive motor rotating a pair of
substantially horizontal drive gears that engage and rotate
the ring gear. The drive gears are arranged so that one is
CA 02354297 2001-09-11
F&K 1086-02-02
- Page 2 -
engaging and rotating the ring gear while the open throat
rotates past the other. In both open and closed throat
tongs, the ring gear is typically held in position during
rotation by rollers rotatably fastened between the top and
bottom tong plates and bearing against the outer periphery
of the ring gear teeth.
A pivoting jaw mechanism is mounted on a cage which rotates
with respect to the tong housing to move the jaws into
gripping engagement with the pipe. The cage typically
comprises top and bottom cage plates located above and
below the ring gear and defining a central cage aperture in
the middle. The cage may have an open throat leading to
the central cage aperture.
In closed throat type power tongs, an end of the pipe is
moved through the central aperture and then the pipe moves
up and down in the aperture as joints are threaded together
or taken apart.
Open throat tongs are moved into position by aligning the
open throats on the tong housing, ring gear, and cage and
passing the pipe through the aligned open throats into the
CA 02354297 2001-09-11
F&K 1085-02-02
- Page 3 -
central aperture. Typically a door closes the open throat
on the tong housing to prevent the pipe from accidentally
escaping from the tongs.
In either type tongs, when the drive begins to rotate the
ring gear, the cage rotates through several degrees with
respect to the ring gear and the jaws move into gripping
engagement with the pipe. Once the jaws are engaged, the
cage and ring gear then rotate together, with respect to
the tong housing.
In a typical set of power tongs, each of a pair of jaws is
pivotally mounted by a bolt to the top and bottom cage
plates. A jaw roller attached to the jaw rests in a valley
on the inner periphery of the ring gear when the jaws are
in an open position. When the ring gear is rotated by the
drive gears, the cage remains substantially stationary,
commonly held by the friction of a brake, and the jaw
roller thus moves out of the valley and up a slope on the
inner periphery of the ring gear and pivots the jaw into
engagement with the pipe, at which point the cage and ring
gear rotate together with the jaws gripping and rotating
the pipe as well. The friction of the brake is overcome by
CA 02354297 2001-09-11
F&K 1086-02-02
- Page 4 -
the force of the rotating ring gear engaging the jaws and
thus the cage. Reversing the direction of rotation of the
ring gear releases the jaws and further reverse rotation
will cause the jaws to re-grip the pipe and rotate same in
the reverse direction.
The orientation of the parts to allow the required
movements relative to each other conventionally requires
that cage bolts and spacers, or equivalent fasteners,
holding the top and bottom cage plates together pass
through the aperture inside the inner periphery of the ring
gear. Commonly different sets of jaws are provided for a
tong assembly to allow for use on pipes with a range of
diameters. The range of jaw sizes that can be accommodated
by any given set of power tongs is limited because the cage
bolts interfere with the operation of the jaws. Moving
these cage bolts and spacers out of the aperture would
allow for a wider throat in open throat tongs, and would,
with either type, accommodate a wider range of jaws, thus
increasing the sizes of pipe that the tongs would service,
and decreasing the need for a separate set of power tongs.
SUMMARY OF THE INVENTION
CA 02354297 2001-09-11
F&K 1086-02-02
- Page 5 -
It is the object of the present invention to provide a
power tong apparatus that can accommodate a wider range of
pipe diameters than is possible with conventional power
tongs.
It is a further object of the invention to provide a ring
gear for such an apparatus that is slotted such that
fasteners holding the top and bottom cage plates together
pass through the slots instead of through the central
aperture of the tongs inside the inner periphery of the
ring gear where they interfere with the operation of the
jaws.
The invention provides, in one aspect, a power tong
apparatus for rotating a pipe. The apparatus comprises a
tong housing defining a central housing aperture. A ring
gear, having an inner periphery defining a central ring
aperture and an outer periphery, is rotatably mounted in
the tong housing such that an inner portion thereof extends
into the central housing aperture such that the central
ring aperture is inside the central housing aperture. A
top cage plate is positioned above a top surface of the
CA 02354297 2001-09-11
F&K 1086-02-02
- Page 6 -
inner portion of the ring gear and a corresponding bottom
cage plate is positioned below a bottom surface of the
inner portion of the ring gear. The top and bottom cage
plates define a central cage aperture oriented such that
the central cage aperture is inside the central ring
aperture. The top and bottom cage plates are fastened
together to form a cage rotatable with respect to the tong
housing and the ring gear. At least one jaw is pivotally
attached to the cage and bears against the inner periphery
of the ring gear and is operative to grip the pipe when the
ring gear is rotated with respect to the cage, and a drive
is operative to rotate the ring gear. The ring gear and
cage rotate about a substantially vertical rotational axis
located substantially in the center of the central cage
aperture. The top and bottom cage plates are fastened
together by a fastener extending through a slot in the ring
gear located between the inner and outer peripheries of the
ring gear, such that the cage plates can rotate with
respect to the ring gear through a limited arc. The
fastener is operative to maintain the cage plates in a
fixed vertical relationship relative to each other.
CA 02354297 2001-09-11
r~&K 1086-02-02
- Page 7 -
The invention provides, in a second aspect, a power tong
apparatus for rotating a pipe comprising a tong housing
defining a central housing aperture and an open throat
extending from an exterior of the tong housing to the
central housing aperture. A ring gear has an inner
periphery defining a central ring aperture, an outer
periphery, and an open throat extending from the outer
periphery to the inner periphery. The ring gear is
rotatably mounted in the tong housing such that an inner
portion thereof extends into the central housing aperture
such that the central ring aperture is inside the central
housing aperture. The ring gear further defines a pair of
slots therethrough located on opposing sides of the central
ring aperture. A tap cage plate is positioned above a top
surface of the inner portion of the ring gear and a
corresponding bottom cage plate is positioned below a
bottom surface of the inner portion of the ring gear. The
top and bottom cage plates define a central cage aperture
oriented such that the central cage aperture is inside the
central ring aperture, and defines an open throat. The top
and bottom cage plates are fastened together by a bolt and
spacer extending through each slot in the ring gear to form
a cage having an open throat extending f rom an exterior of
CA 02354297 2001-09-11
F&K 1686-02-02
- Page 8 -
the cage to the central cage aperture . The top and bottom
cage plates are maintained in fixed relationship by the
spacer, and the cage is rotatable with respect to the tong
housing and the ring gear. At least one jaw is pivotally
attached to the cage and bears against the inner periphery
of the ring gear and is operative to grip the pipe when the
ring gear is rotated with respect to the cage. A drive is
operative to rotate the ring gear; and the ring gear and
cage rotate about a substantially vertical rotational axis
located substantially in the center of the central cage
aperture.
The invention provides, in a third aspect, a ring gear
adapted for rotatable mounting about a rotational axis in a
power tong apparatus for rotating a pipe. The ring gear
comprises an outer periphery adapted for engagement with a
drive operative to rotate the ring gear and an inner
periphery shaped to form at least one valley, and defines a
central ring aperture . A slot is def fined by the ring gear
between the outer and inner peripheries. The slot is
oriented to accommodate a bolt and spacer therethrough such
that the bolt and spacer can secure a top cage plate,
positioned above the ring gear, to a bottom cage plate
CA 02354297 2001-09-11
F&K 1086-02-02
- Page 9 -
positioned below the ring gear. The slot is further
oriented to permit limited rotational movement of the ring
gear with respect to the top and bottom cage plates.
Conventionally, the fastener attaching the top cage plate
to the bottom cage plate passes through the central ring
aperture inside the inner periphery of the ring gear.
Removing this fastener from the conventional location frees
essentially all the area of the central ring aperture
inside the inner periphery of the ring gear for the jaw
mechanism, allowing for larger pipes and jaws for the same
diameter of ring gear.
DESCRIPTION OF THE DRAWINGS:
While the invention is claimed in the concluding portions
hereof, preferred embodiments are provided in the
accompanying detailed description which may be best
understood in conjunction with the accompanying diagrams
where like parts in each of the several diagrams are
labeled with like numbers, and where:
CA 02354297 2001-09-11
F&K lOk3f -OJ-02
- Page 10 -
Fig. 1 is a schematic top view of an apparatus of the
invention;
Fig. 2 is a schematic cross-sectional view of the apparatus
of Fig. 1;
Fig. 3 is a schematic top view of the cage, jaws and ring
gear with the jaws open to allow positioning on a pipe;
Fig. 4 is a schematic top view of the cage, jaws and ring
gear with the jaws closed on a pipe;
Fig. 5 is a schematic top view of a ring gear of the
invention showing the location of cage bolts and spacers
for attaching top and bottom cage plates.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS:
Figs. 1 and 2 illustrate an open throat power tong
apparatus 1 for rotating a pipe. A closed throat power
tong apparatus will work in the same fashion, and is not
further illustrated. The open throats can be aligned to
CA 02354297 2001-09-11
F&K 1086-02-D2
- Page 11 -
provide an open passage 2 from an exterior of the apparatus
1 the interior thereof.
The apparatus 1 comprises a tong housing 3 defining a
central housing aperture 5. The tong housing 3 includes
top and bottom tong plates, 6, 7 and a sidewall 8.
A ring gear 10 has an inner periphery 12 defining a central
ring aperture 13 and an outer periphery 14. The ring gear
10 is rotatably mounted in the tong housing 3 by a
plurality of housing rollers 16 mounted in the tong housing
3 and bearing against the outer periphery 14 to maintain
the ring gear 10 in its proper position, rotating about the
substantially vertical rotation axis R. An inner portion
10A of the ring gear 10 extends into the central housing
aperture 5 such that the central ring aperture 13 is inside
the central housing aperture 15.
A top cage plate 20 is positioned above a top surface of
the inner portion 10A of the ring gear 10 and a
corresponding bottom cage plate 21 is positioned below a
bottom surface of the inner portion 10A of the ring gear
10. The top and bottom cage plates 20, 21 are fastened
CA 02354297 2001-09-11
F&K 1086-02-02
- Page 12 -
together to form a cage 25 rotatable with respect to the
tong housing 3 and the ring gear 10. In the illustrated
embodiment the top cage plate 20 substantially fills the
central housing aperture 5, and rotates on rollers (not
illustrated) which run in a groove in the ring gear 10. In
other configurations, the top cage plate 20 could extend
over an inner portion of the top tong plate 6 and rotate on
rollers attached to the tong plate. Various configurations
are well known in the art.
The top and bottom cage plates 20, 21 define a central cage
aperture 24 oriented such that the central cage aperture 24
is inside the central ring aperture 13. The cage 25
rotates about the rotation axis R, located in the center of
the central cage aperture 24.
The top and bottom cage plates 20, 21 are fastened together
by fasteners comprising a cage bolt 26 and spacer 27
extending through slots 18 in the ring gear 10 located
between the inner and outer peripheries 12, 14 of the ring
gear 10 and on opposing sides of the central ring aperture
24. Thus the cage 25 can rotate with respect to the ring
gear 10 through a limited arc defined by the slots 18. The
CA 02354297 2001-09-11
r&K 1086-02-02
- Page 13 -
slots 18 are an arc-shape, the arc having a center located
on the rotational axis R. The spacer 27 is operative to
maintain the cage plates 20, 21 in a fixed vertical
relationship relative to each other.
A drive motor 28 rotates drive gears 29 which mesh with
teeth 11 on the outer periphery 14 of the ring gear 10 and
cause same to rotate.
Figs. 3 and 4 schematically illustrate the operation of a
pair of jaws 30. The slots 18 in the ring gear 10 are
omitted for clarity of illustration, but the location of
the cage bolts 26 is indicated. Each jaw 30 is pivotally
attached to the cage 25 at pivot pins 32. A jaw roller 34
bears against the inner periphery 12 of the ring gear 10.
The inner periphery 12 of the ring gear 10 defines a pair
of valleys 36 located on opposing faces of the inner
periphery 12. The valleys 36 have centers removed from a
centerline CL of the cage aperture 24 in a direction
opposite the open throat of the ring gear 10. This
configuration is preferred in order to properly align the
jaws 30 and pipe 40.
CA 02354297 2001-09-11
F&K 1086-02-02
- Page 14 -
In Fig. 3 , the j aw rollers 34 are located in the bottom of
the valleys 36 and the jaw mechanism is open such that the
apparatus 1 can be moved into position on a pipe 40.
Conventionally, rotation of the cage 25 is retarded by a
brake (not shown) such that when the drive motor 28 starts
to rotate the ring gear 10 in direction D, the cage 25
stands still and in effect rotates with respect to the ring
gear 10. The jaw rollers 34 move out of the bottoms and up
the slopes 38 of the valleys 36 thereby moving the jaws 30
into engagement with the pipe 40 as illustrated in Fig. 4.
The mechanism essentially binds against the pipe and then
the ring gear 10, cage 25, jaws 30, and pipe 40 all rotate
together. Reversing rotation of the ring gear first
releases the jaws 30 and then re-engages them to rotate the
pipe 40 in the opposite direction.
The top and bottom cage plates 20, 21 are firmly held in
place relative to each other by the cage bolts 26 and the
pivot pins 32.
Figs. 3 and 4 show that removal of the cage bolts from the
conventional location inside the central ring aperture 13
allows essentially all the area inside the inner periphery
CA 02354297 2001-09-11
F&K 1086-02-02
- Page 15 -
12 of the ring gear 10 to be occupied by the pipe 40, and
by the jaws 30 and jaw rollers 34 as they move along the
inner periphery of the ring gear 10.
Fig. 5 illustrates a typical ring gear 10 of the invention,
adapted for rotatable mounting about a rotational axis R in
a power tong apparatus 1 for rotating a pipe 40. The outer
periphery 14 is adapted for engagement by meshing gear
teeth 11 with a drive operative to rotate the ring gear 10.
The inner periphery 12 is shaped to form valleys 36, and
defining a central ring aperture 13. Slots 18 are defined
by the ring gear 10 between the outer and inner peripheries
12, 14 on opposing sides of the central ring aperture 13.
The slots 18 are oriented to accommodate a cage bolt 26 and
spacer 27 therethrough such that the cage bolt 26 and
spacer 27 can secure a top cage plate 20, positioned above
the ring gear 10, to a bottom cage plate 21 positioned
below the ring gear 10. The slots 18 permit limited
rotational movement of the ring gear 10 with respect to the
top and bottom cage plates 20, 21.
The slots 18 as illustrated have an arc-shape, the arc
having a center located on the rotational axis R. This
CA 02354297 2001-09-11
F&K 1086-02-02
- Page 16 -
configuration requires a minimum width slot 18, the same
width as the spacer 27. The cage bolt and spacer 26, 27
rotate around the rotational axis R and follow the slot 18.
The foregoing is considered as illustrative only of the
principles of the invention. Further, since numerous
changes and modifications will readily occur to those
skilled in the art, it is not desired to limit the
invention to the exact construction and operation shown and
described, and accordingly, all such suitable changes or
modifications in structure or operation which may be
resorted to are intended to fall within the scope of the
claimed invention.
