Note: Descriptions are shown in the official language in which they were submitted.
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1 BACKGROUND OF THE INVENTION
3 1. Field of the Invention:
This invention relates in general to earth drilling
6 equipment and in particular to rotary power slips mounted
7 concentrically with the pipe opening in a rotary drilling
8 table.
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2. Description of the Prior Art:
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12 U.S. Patent No. 4,333,209 (Hers), entitled "Rotary
13 Power Slips", issued on June 8, 1982, discloses rotary
I power slips having a housing mounted in a rotary table of
an earth drilling rig. Air, from a stationary fluid source
16 on the drilling rig, is transferred to pneumatic cylinders
17 in the housing to operate the slips. A perforated annular
I bladder is expanded to form an expansive fluid duct between
it a stationary seal ring, connected to the stationary fluid
source, and an air transfer plate, which rotates with the
I housing
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23 After the slips have been raised by the cylinders, the
24 fluid pressure is cut off, releasing fluid pressure to the
cylinders from the stationary source and the seal ring
US disengages. In prior art devices, such as Hurst me-
27 chanical means are used to lock the slips in the raised
28 position. Such mechanical means are subject to jolts and
29 vibrations common to drilling floors. An improved apt
pyrites was needed to lock the slips in the raised position.
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32 In addition, improvements were needed in the rotary
33 power slips, so that the power slips will take more Brie-
34 soon, leak less, and take more pneumatic prosier. Also,
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1 it was desired to prude a seal ring which will be simpler
and faster to replace under field conditions.
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STY JAR Y OF TO E I No. N 1 I O N
3 Rotary power slips have been improved by replacing the
4 annular perforated bladder with a pair of annular expansive
rings, having inner and outer edges mounted in grooves on
6 the upper surface of the stationary air transfer ring. The
7 edges of the expansive rings are held in the grooves by
8 retaining rings. The grooves in the air transfer ring are
9 preferably undercut to form counter bores, into which the
edges of the expansive rings are mounted. The rotary power
11 slips of the invention can withstand more abrasion than the
12 rotary power slips in the prior art, and the expansive rings
13 of the invention teak less and are able to take more
14 pressure than the prior art designs. Additionally, the
expansive rings, held in place by retaining rings, are
16 easier to service and to replace under field conditions.
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18 The improved rotary power slips of the invention have
19 a pilot operated check valve for holding the air pressure
in one end of the pneumatic cylinders to lock the slips in
21 the released position. The check valve is piloted off of
22 the fluid conduit to the other end of the cylinders, so that
23 whenever pneumatic pressure is applied to the other end of
24 the cylinders, the check valve will open and allow the slips
to be lowered to the tripping position. The pilot operated
26 check valve will thus hold the slips in the upper retracted
27 position when pneumatic pressure from the station air
28 source is removed. The slips are not allowed to return to
2g the gripping position, until pneumatic pressure is applied
to the proper end of the pneumatic cylinders.
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32 The above, as well as additional objects, features,
33 and advantages of the invention, will ~t?COIIle apparent in
34 the following detailed description.
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BRIEF DESCRIPTION OF DRAWINGS
3 Fig. 1 is a perspective view, partially in section,
4 of the improved rotary power slips of the invention, with
the slips in the lower, gripping position.
7 Fig. 2 is a perspective view, partially in section,
8 of the improved rotary power slips of the invention, with
9 the slips in the upper, retracted position.
11 Fig. 3 is a close-up sectional view of the seal ring,
12 the air transfer ring, and the annular expansive rings.
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14 Fig. 4 is a top view of the expansive rings.
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16 Fig. 5 is a sectional view of the air transfer ring
17 and expansive rings as seen along lines 5-5 in Fig. 4.
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19 Fig. 6 is a schematic drawing of the pneumatic system
20 for raising and lowering the slips.
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DET~.ILEV DESCRIPTION OF THE PREFERRED EMBODIMENT
3 The improved rotary power slips 11, shown in Figs. 1
4 and 2, have a body 13 which is mounted concentrically with
the pipe opening in a rotary table of an earth drilling
6 rig. The body 13 is supported by, and rotates with, the
7 rotary table. The body 13 supports three slips 15 which
8 are linked together my a slip ring I Each slip 15 has
9 a multitude of replaceable toothed inserts 19, and the
slips 15 together form slip means for gripping a pipe
11 within the rotary table when the slips 15 are in their
12 lower, gripping position shown in Fig. 1. When the slips
13 15 are raised to their upper retracted position, shown in
14 Fig. 2, the slips 15 release the pipe and the pipe may
travel freely through the rotary table.
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17 The slips 15 are raised and lowered by means of
18 pneumatic cylinders 21, which are connected to the slip
19 ring 17. The slips 15 are connected to the slip ring 17
by means of rollers 23 which are inserted through eon-
I grated slots 25 in the slip ring 17. The rollers 23 move
22 back and forth in the slots 25 as the slips 15 move up and
23 down between the gripping position shown in jig. 1 and the
I retracted position shown in Fig. 2. The slips 15 have
frusto-conical surfaces 27, 29 which contact thy inner
26 surface of the body 13 to move the slips 15 inward and
27 outward between the two slip positions.
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29 The slips 15 and cylinders 21 rotate with the body 13
of the power slips 11. When the body 13 stops rotating,
31 the cylinders 21 may be located in any position around the
32 hole. Air pressure must be delivered to the pneumatic
33 cylinders I from a stationary air Tony Al yoga. I
34 regardless of the positions ox thought cylinders 'l whet toe
rotation of the power slips 11 has chased. Irlle? transfer
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1 of air pressure from the stationary components of the
2 power slips 11 to the rotary components is accomplished by
3 means of a seal ring 33, shown in detail in Fig. 3. The
4 seal ring 33 is attached to the bottom of the body 13 by
means of bolts 35 and rotates therewith A pair of annular
6 air passageways 37, 38 are located on the upper side of the
7 seal ring 33. One of these air passageways 37 is in fluid
8 contact with secondary fluid conduits 39 which lead to the
9 upper ends of the pneumatic cylinders 21. The other air
passageway 38 is in fluid contact with the secondary fluid
11 conduits 41 which lead to the lower ends of the pneumatic
12 cylinders 21. The transverse lower surface 43 of the seal
13 ring 33 also has a pair of annular, triangular grooves 45,
14 46. The outer air passageway 37 and the outer triangular
lo groove 45 are connected by a single port 47 as shown in
16 Fig. 3. The inner air passageway 38 and the inner groove
17 46 are likewise connected by a port (not shown) which is
18 located on the opposite side of the seal ring 33.
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An annular bearing support ring 49 is also attached
21 to the body 13 by the bolts 35. The bearing support ring
22 49 supports six rollers 51, which are attached to an
23 annular air transfer ring 53 as shown in Fig. 5. The air
24 transfer ring 53 remains stationary as the bearing support
ring 49 and the body 13 of the rotary power slips 11
26 rotate. There are three concentric grooves 55 in the
27 transverse upper surface 57 of the air transfer ring it.
28 These grooves 55 have undercuts to form annular counter-
29 bores So in the grooves 55. A pair of concentric expansive
rings 61, 62 are secured to the upper surface 57 of the air
31 transfer ring 53 by mounting the inner and outer edges of
32 the expansive rings 61, 62 in the counter bores 59 in the
33 grooves 55 on thellpper surface 57 of the air transfer ring
34 53. Retainer rings 63 are placed in the groves 55,
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1 compressed against the edges of the expansive rings 61, 62
2 to lock the expansive rings 61, 52 in place. A pair of
3 primary Clued conduits 65 pass through the air transfer
4 ring 53 frown the bottom surface 67 to the top surface 57.
One of the primary fluid conduits 65 exits beneath the
6 outer expansion ring 61, as shown in Fig. 3. The other
7 primary fluid conduit (not shown) exits the top surface 57
8 of the air transfer ring 53 beneath the inner expansion
9 ring 62. The primary fluid conduits 65 are in fluid
contact with lines 69, 70 which lead to a foot control 71
11 as shown in Fig. 6. Each expansive ring 61, 62 has a small
12 hole 73, 74 located 180 degrees away from the primary fluid
13 conduit 65 beneath the expansive ring 61, 62. Thus, when
14 air pressure is applied through the primary fluid conduit
lo 65, the expansive ring 61 will be expanded upwards as shown
16 in Fig. 3. The air pressure will then travel around the
17 expansive ring 61 and exit through the hole 73. When tune
18 expansive ring 61 is expanded, the expansive ring 61
19 contacts the lower surface of the seal ring 33 on each side
of the groove 45. This forms an annular expansive fluid
21 duct 75. ennui air pressure is applied through the other
22 primary fluid conduit (not shown), the other expansive
23 ring 62 will be expanded. The air pressure then travels
24 around the expansive ring I and exits through the hole 74.
Expanded ring 62 contacts the seal ring 33 to form an
26 annular expansive fluid duct in the same manner as the
27 outer expansive ring 61. An inner wear strip 76 is located
28 between the air transfer ring 53 and the bearing support
29 ring 49. An outer mud skirt 77 is located on the outer
circumference of the air transfer ring 53 to keep drill-
31 in mud away from the expansive rings 61, 62.
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33 Fig. 6 illustrates tile pneumatic system Ox the rotary
34 power slips 11. 'Lowe pllcllmatic source is all air Allah 31
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mounted on the drilling rig. Air flow passes from the air
tank 31 through a filter 78, a regulator 79, and
lubricator 81 to the safety valve 83. The foot valve 71
then passes the air flow through a selected one of the
lines 69, 70 to the seal ring 33. The air flow passes from
one of the lines, 69 or 70, to one of the primary fluid
conduits 65 through the air transfer ring 53. The air
pressure expands one ox the expansive rings 61, or 62,
until the expansive ring contacts the seal ring 33 to form
one of the expansive fluid ducts 75. The air flow passes
beneath the expansive ring, 61 or 62, to the hole, 73 or
74, and then through the expansive fluid duct 75 to the
port 47. The port 47 passes the air flow to the air
passageways, 37 or 38, and then on to the secondary fluid
conduits, 39 or 41. The secondary fluid conduit 39, or 41,
passes the air flow to the top or the bottom of the
pneumatic cylinders 21 to raise or lower the slip means 15.
A pilot operated check valve 85 is located in the
secondary fluid conduit 41 leading to the bottom of the air
cylinders 21. The pivot operated check valve 85 allows free
flow from the seal ring 33 to the bottom of the cylinders 21.
Flow in the opposite direction, from the bottom of the cylinders
21 to the seal ring 33 is blocked. The check valve 85 is thus
a check valve means for holding the pressure in one end of the
fluid cylinder 21 to keep the slip means 15 in the raised
position. The check valve 85 keeps the slips 15 in the raised
position, even if air pressure from the stationary source is cut
off.
When it is desired to lower the slips 15, pressure must
be applied to the upper end of the cylinders 21 through the
secondary fluid conduit 39. Some of this pressure flows through
a pilot line 87 to the check valve 85. Pressure in the pilot
line 87 causes the check valve 85 to open, allowing pressure to
escape from the bottom of the air cylinders 21. us air pressure
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escapes from the lower end of the cylinders 21, the slips 15
are lowered to their gripping position, as shown in Fig. 1.
In operation, to raise the slips to their retracted
position as shown in Fig. 2, air pressure from the air tank
31 is applied through the filter 78, the regulator 79 and
the lubricator 81 to the safety valve 83. The foot valve
71 then applies the air pressure through one of the lines
69 to the air transfer ring 53. The air passes through one
of the primary fluid conduits 65 to beneath one of the
expansive rings 61. The air pressure causes the expansive
ring 61 to expand to contact the bottom of the seal ring
33. The expansive ring 61 and the groove 45 in the seal
ring 33 create a expansive fluid duct 75. The air beneath
the expansive ring 61 passes through the hole 73 into the
expansive fluid duct 75. The air then passes through the
port 47 to an air passageway 37. The air passageway 37
conducts the air through the check valve 85 to the sea-
ondary fluid conduits 41 in the body 13 of the rotary power
slip 11. The air in the top of the air cylinders 21 is
exhausted through secondary fluid conduits 39, and the
secondary fluid conduits 41 conduct the air to the bottom
of the air cylinders 21 to raise the slip ring 17 and the
slips 15 to the upper retracted position shown in Fig. 2.
The check valve 85 prevents the air pressure in the lower
half of the air cylinder 21 from escaping and locks the
slips 15 in the raised position. The foot valve 71 is then
moved to a neutral position, removing fluid pressure from
the seal ring 33.
In order to lower the slips 15, air pressure from the
air tank 31 is fed by the foot control 71 through the other
line 70 to the air transfer ring 53. The line 70 is
connected to the other primary fluid conduit snot shown).
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1 The primary fluid conduit (not shown) conducts the air to
2 beneath the other expansive ring 62. The expansive ring
3 62 is expanded to contact the seal ring 33 an to form the
4 expansive fluid duct 75. The air escapes through the hole
74 into the expansive fluid conduit 75. The air travels
6 through the portent shown) into the air passageway 38 and
7 then into the secondary fluid conduit 39. The secondary
8 fluid conduit 39 carries the air pressure to the upper half
g of the pneumatic cylinders 21. The check valve 85 is
piloted off of one of the secondary fluid conduits 39, to
11 open the check valve 85 when fluid pressure is applied to
12 the secondary fluid conduit 39. This allows air pressure
13 in the bottom half of the air cylinders 21 to escape
14 through the secondary fluid conduits 41 and allows the
lo slips I to be lowered to their gripping position.
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17 The rotary power slips 11 of the invention provide
18 several significant advantages over the prior art. The
19 expansive rings 61, 62 are more reliable and can withstand
more pressure and more abrasion than the expansive means
21 used in prior devices. The expansive rings 61, 62 are also
22 easier to service and to replace under field conditions.
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24 The pilot operated check valve 85 makes the improved
rotary power slips 11 safer and more economical than prior
26 art devices. The check valve 85 holds the slips 15 in the
27 upward, retracted position, even when air pressure from
28 the stationary source 31 is removed.
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While the invention has been shown in only one of its
31 forms, it should be apparent to those skilled in the art
32 that it is not so limited, but is susceptible to various
33 changes and modifications without departing prom the
34 spirit there
