U.S. patent number 3,742,562 [Application Number 05/186,096] was granted by the patent office on 1973-07-03 for well pipe supporting unit.
Invention is credited to George H. Haby.
United States Patent |
3,742,562 |
Haby |
July 3, 1973 |
WELL PIPE SUPPORTING UNIT
Abstract
A unit for supporting a well pipe and including a body structure
carrying a plurality of pipe gripping slips which are supported by
individual vertically movable carriers preferably taking the form
of upwardly projecting and vertically moveable posts. These
carriers are actuable by an essentially annular cam which is
shiftable arcuately about the axis of the gripped pipe by power
actuated means. The slips are suspended from the carriers in a
manner enabling the slips to move radially outwardly to laterally
retracted positions as they are shifted upwardly.
Inventors: |
Haby; George H. (Altadena,
CA) |
Family
ID: |
22683645 |
Appl.
No.: |
05/186,096 |
Filed: |
October 4, 1971 |
Current U.S.
Class: |
188/67 |
Current CPC
Class: |
E21B
19/07 (20130101) |
Current International
Class: |
E21B
19/00 (20060101); E21B 19/07 (20060101); A44b
021/00 () |
Field of
Search: |
;24/263DK,263DG,263DA |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gilliam; Paul R.
Claims
I claim:
1. A well pipe supporting unit comprising a body structure to
extend about a pipe, a plurality of slips movable upwardly and
downwardly relative to said body structure between lower active
pipe gripping positions and upper retracted positions, inclined
surfaces for deflecting said slips inwardly against a pipe upon
downward movement of the slips, an actuating structure extending
generally arcuately about the axis of said pipe and mounted to turn
about said axis relative to said body structure and said slips, a
plurality of generally vertical slip carrier posts mounted to said
body structure at circularly spaced locations for longitudinal
upward and downward movement relative to the body structure along
individual axes, coacting cam means on said posts and said
actuating structure operable to cam the posts upwardly and
downwardly in response to turning movement of the actuating
structure about said pipe axis, and a plurality of connections
suspending upper portions of said slips from said different posts
respectively for upward and downward movement therewith and for
radially outward and inward movement relative to said posts upon
said upward and downward movements respectively. pg,17
2. A well pipe supporting unit as recited in claim 1, including
power operated means for moving said actuating structure
essentially arcuately about said axis of the pipe.
3. A well pipe supporting unit as recited in claim 1, including
means yieldingly urging said slip carrier posts upwardly relative
to said body structure.
4. A well pipe supporting unit as recited in claim 1, in which said
actuating structure is essentially annular, said cam means
including a plurality of inclined cam slots in said actuating
structure which advance vertically as they advance circularly about
said axis, and a plurality of cam follower rollers mounted
rotatably to said posts and received in said slots for actuation
upwardly and downwardly upon rotary movement of the actuating
structure.
5. A well pipe supporting unit as recited in claim 1, including
projections on said posts extending laterally with respect to said
individual axes of the posts, and a plurality of guideways
receiving said projections in a relation enabling upward and
downward movement of the posts relative to the body structure but
restraining the posts against turning movement about said
individual axes.
6. A well pipe supporting unit as recited in claim 1, in which said
body structure contains a plurality of circularly spaced socket
recesses slidably receiving said posts and guiding them for said
upward and downward movement along said individual axes, there
being a plurality of rollers mounted rotatably to said posts
respectively to turn about generally horizontally axes, and
generally vertical guideways carried by the body structure and
movably receiving said rollers in a relation allowing upward and
downward movement thereof while restraining turning movement of the
posts about their individual axes.
7. A well pipe supporting unit as recited in claim 1, in which said
connections include inclined track means carried by said posts, and
hangers projecting upwardly from and suspending said slips and
engaging and suspended by and movable along said track means.
8. A well pipe supporting unit as recited in claim 1, in which said
body structure includes a plurality of complementary body sections
relatively movable to an open condition enabling movement of the
body structure from about the pipe, said actuating structure being
essentially annular and including a plurality of complementary
essentially arcuate sections carried by said body sections
respectively for relative opening movement therewith, there being a
plurality of powered mechanisms carried by said body sections
respectively for moving said sections of the actuating structure
arcuately relative thereto.
9. A well pipe supporting unit as recited in claim 1, in which said
posts have lower portions mounted within circularly spaced socket
recesses in said body structure and guided thereby for said upward
and downward movement relative to the body structure, there being
springs yieldingly urging said posts upwardly, each of said
connections including an arm structure projecting generally
radially inwardly from an upper portion of one of said posts and
forming track means, and a bracket attached to the associated one
of said slips and projecting upwardly therefrom and having roller
means movable generally radially inwardly and outwardly in said
track means, said track means being inclined to urge said roller
means and suspended slip radially outwardly along said track means
by gravity in response to the downward forces exerted by the weight
of said slip when the posts and slips are raised upwardly.
10. A well pipe supporting unit as recited in claim 9, in which
said body structure is formed of two complementary halves
interconnected for relative opening movement to enable removal of
the well pipe supporting unit from about a well pipe, said
actuating structure being essentially annular and formed of two
complementary halves movably carried by said two body halves
respectively and relatively openable therewith, there being two
piston and cylinder mechanisms carried by said two body halves
respectively for moving said two halves respectively of the
actuating structure relative to the associated body halves.
11. A well pipe supporting unit as recited in claim 10, in which
said actuating structure is located at a radially inner side of
said posts and beneath said inwardly projecting arm structures,
said cam means including a cam follower roller carried at a
radially inner side of each of said posts and engaging a coacting
cam slot formed in said actuating structure, there being a second
roller carried at the radially outer side of each of said posts,
and guideways carried by the body structure and receiving said last
mentioned rollers in a relation permitting upward and downward
movement thereof while preventing turning of the posts about their
individual axes.
12. A well pipe supporting unit as recited in claim 1, in which
said cam means include a plurality of inclined cam surfaces and
engaging followers, said cam surfaces having first portions of
relatively abrupt inclination acting upon initial arcuate movement
said actuating structure to cause movement of the slips downwardly
and inwardly at a relatively rapid rate, and said cam surfaces
having second portions of less abrupt inclination acting to then
automatically convert to a slower rate of downward and inward
movement of the slips upon further downward movement of the
actuating structure.
13. A well pipe supporting unit comprising a body structure to
extend about a pipe, a plurality of slips movable upwardly and
downwardly relative to said body structure between lower active
pipe gripping positions and upper retracted positions, inclined
surfaces for deflecting said slips inwardly against the pipe upon
downward movement of the slips, an actuating structure mounted for
movement generally horizontally relative to said body structure,
and cam means associated with said actuating structure and at least
one of said slips for effecting downward movement of said slip upon
said generally horizontal movement of the actuating structure, said
cam means including an inclined cam surface and a cam follower
engaging said cam surface, said cam surface having a first portion
of relatively abrupt inclination acting upon initial horizontal
movement of said actuating structure to cause movement of said one
slip downwardly and inwardly at a relatively rapid rate, and said
cam surface having a second portion of less abrupt inclination
acting to then automatically convert to a slower rate of downward
and inward movement of said one slip upon further movement of the
actuating structure.
14. A well pipe supporting unit as recited in claim 13, in which
said actuating structure extends essentially arcuately about the
axis of said pipe and has said camming surface formed thereon, said
cam follower being connected to said one of the slips for movement
therewith.
15. A well pipe supporting unit as recited in claim 14, in which
said actuating structure has a detent notch engageable by said
follower in a relation releasably retaining said follower in an
uppermost setting of the associated slip.
16. A well pipe supporting unit as recited in claim 13, in which
said actuating structure extends generally annularly about the axis
of said pipe and has a plurality of inclined cam slots engaging and
actuating a plurality of said cam followers connected to said slips
respectively, there being a plurality of said inclined camming
surfaces defining upper edges of said slots respectively and each
having a first portion of relatively great inclination and a lower
end portion of reduced inclination, there being surfaces at
undersides of the slots having generally horizontal portions at the
upper ends of the slots defining upwardly facing detent notches in
which said followers are releasably retained in upper positions of
the slips.
Description
BACKGROUND OF THE INVENTION
This invention relates to improved well pipe supporting units,
adaptable for use as well pipe elevators, support `spiders,` or the
like.
In running a well casing into or out of a well, it is customary to
suspend the casing, and raise and lower it, by means of an
`elevator,` which is power actuable upwardly and downwardly, and
which normally includes a number of slips for releasably engaging
and gripping the suspended pipe. Similarly, the casing may in some
circumstances be supported stationarily by a spider, which also
normally includes a number of slips.
As deeper and deeper wells have been drilled in recent years, the
weight of the casing strings required in these wells has increased
so much that conventional elevators and spiders have had great
difficulty in supporting this increased weight, and in avoiding
damage to the supported heavy strings of pipe. In addition, many of
these conventional elevators and spiders are relatively difficult
to actuate between gripping and released conditions, with resultant
expenditure of excessive time and effort in actuating and releasing
them during the lowering or withdrawal of an extended length of
casing.
SUMMARY OF THE INVENTION
The present invention provides an improved well pipe supporting
unit which is especially well adapted for supporting these
extremely long strings of casing or other well pipe. As will
appear, the mechanical construction and method of operation of
these supporting units are such as to maximize the load supporting
capacity of the units while avoiding an excessive increase in their
size or weight. Further, the devices are very positively and
quickly actuable by built-in powered means between gripping and
released conditions. Certain particular features of the invention
relate to a preferred manner in which the slips may be cammed
inwardly toward a pipe first at a relatively rapid rate to
effectively center the pipe in the device, and then at a reduced
rate to set the slips in final gripping condition.
With regard to structure, a unit embodying the invention includes a
slip actuating cam structure which extends and moves arcuately
about the axis of the gripped pipe. A plurality of slips are
mounted movably to the body of the device by individual carrier
parts, preferably taking the form of vertically moveable posts
slidably received within and projecting upwardly from mounting
sockets or guideways in the body structure. The slips are mounted
to these carriers by connections which allow radially outward
retracting movement of the slips upon upward movement thereof by
the cam mechanism. Desirably, the body structure is formed as a
plurality of body sections which are openable to a condition
allowing removal of the unit laterally from about a pipe, and the
cam structure may be formed similarly as a plurality of sections
mounted to the various body sections respectively. Piston and
cylinder mechanisms or other power units are mounted on the
different body sections for actuating the corresponding cam
sections relative thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other features and objects of the invention will be
better understood from the following detailed description of the
typical embodiment illustrated in the accompanying drawings in
which:
FIG. 1 is a somewhat diagrammatic representation of a portion of a
well drilling rig having an elevator constructed in accordance with
the invention;
FIG. 2 is a fragmentary perspective view of the elevator of FIG. 1,
with one-half of the upper cover removed to reveal the inner
mechanism of the apparatus;
FIG. 3 is a plan view of the elevator taken on line 3--3 of FIG.
1;
FIG. 4 is an enlarged horizontal section taken on line 4--4 of FIG.
2 just beneath the top wall of the cover part;
FIG. 5 is an enlarged fragmentary vertical section taken on line
5--5 of FIG. 4;
FIG. 5a is a horizontal section taken on line 5a-5a of FIG. 5;
FIG. 6 is a fragmentary view similar to a portion of FIG. 4, but
showing the slips in their retracted positions;
FIG. 7 is a fragmentary vertical section taken on line 7--7 of FIG.
6;
FIG. 8 is a fragmentary vertical section taken on line 8--8 of FIG.
7;
FIG. 9 is a fragmentary view of the cam taken essentially on line
9--9 of FIG. 5;
FIG. 10 is a view similar to FIG 9 but taken on line 10--10 of FIG.
7;
FIG. 11 is an enlarged fragmentary vertical section taken on line
11--11 of FIG. 4;
FIG. 12 is a view taken on line 12--12 of FIG. 4; and
FIG. 13 is a fragmentary vertical section taken on line 13--13 of
FIG. 5.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring first to FIG. 1, I have shown at 10 a well pipe
supporting unit constructed in accordance with the invention and
illustrated as it appears when in use as an elevator, for
suspending and moving vertically a string of casing or other well
pipe, the upper stand of which is represented at 11. The casing
extends downwardly along a vertical axis 12 through the usual
rotary table represented diagrammatically at 13, and into the well.
Elevator 10 is itself suspended and actuated upwardly and
downwardly by the conventional hoisting mechanism of the rig,
including a power actuated block and tackle 14 whose traveling
block 15 carries a main hook 16 having two smaller side hooks 16a
supporting the elevator through a pair of vertical support rods
18.
When it is desired to utilize the well pipe supporting unit 10 as a
`spider` rather than an elevator, support rods 18 may be detached
from the remainder of the unit, and the unit may then be supported
on the rotary table in appropriate manner to suspend the pipe 11 in
stationary position.
Unit 10 includes a generally annular rigid and very strong body 19
extending about the suspended casing 11 and its axis 12, and
preferably consisting of two identical complementary essentially
semicircular halves or sections 20 and 21 meeting in the vertical
diametrical plane represented at 22 in FIG. 4. At the two
diametrically opposite locations at which the opposite ends of the
two body sections 20 and 21 meet, these body sections have
interfitting connector or hinge lugs 23 (see FIG. 12), containing
vertically aligned registering cylindrical apertures or passages 24
within which two vertical externally cylindrical hinge or connector
pins 25 are removably received to releasably secure the two body
sections together in their FIG. 4 assembled relation. These pins 25
are centered about and extend vertically along two parallel
vertical axes 26 and 27 (FIG. 4) which are positioned symmetrically
and at diametrically opposite sides with respect to the main axis
12 of the tool and casing. Pins 25 are of course close fits within
the apertures 24, and may have slightly enlarged upper heads 28
limiting downward movement of the pins relative to the body
sections in the FIG. 12 assembled condition of the parts, with one
or both of the pins desirably having a loop or bail 29 at its upper
end by which the pin may be grasped to pull it upwardly from the
body sections and thus detach the body sections for removal
laterally from about the casing.
At opposite sides of each of the two pins 25, body sections 20 and
21 carry two identical upstanding suspension lugs 30 and 31, having
aligned openings 32 receiving a horizontal pin 33 about which a
lower eye portion 34 of one of the rods 18 is received in
suspending relation. A spacer bushing 35 may be received about each
of the pins 33 and between lugs 30 and 31, with pin 33 desirably
having an enlarged head 36 at one of its ends adapted to be
detachably connected to the associated lug 31 by a screw or other
fastener 37.
In normal use, the two body sections will ordinarily be left in
their connected assembled condition, with the body and carried
parts being removed from about the casing by withdrawing unit 10
upwardly past the upper end of the casing. If circumstances arise
in which it becomes necessary to remove the unit 10 from about the
casing by movement in a lateral direction, the two pins 33 may be
detached from the body sections, and one of the vertical pins 25
may then be withdrawn upwardly out of its position of connection to
the hinge or connector lugs 23, to thus release the two body
sections 20 and 21 for relative opening or swinging movement about
the second of the two vertical pins 25 as a hinge, and to an open
position such as that represented in broken lines in FIG. 3, in
which the entire unit may be easily moved laterally from about the
casing.
At their lower ends, the two body sections 20 and 21 carry two
complementary semicircular downwardly projecting centering or
locating elements 38, suitably secured to the body sections as by
bolts 39, and having downwardly flaring frustoconical portions 40
which are engageable with the upper end of the casing as the unit
10 is moved downwardly about the casing, to automatically deflect
the unit 10 laterally to a properly centered relation with respect
to the pipe. The two semicircular elements of course meet or
substantially meet in the same plane 22 of FIG. 4 in which the body
sections 20 and 21 meet.
Within the body structure 19 formed by sections 20 and 21, there
are carried several (preferably 4) identical pipe gripping slips
41, whose inner faces carry gripping dies 42 engageable with the
pipe to suspend it and hold it in fixed position when the slips are
in their set or active conditions. Each of the slips extends
arcuately through approximately 90 degrees about vertical axis 12,
with two of the slips being contained within body section 20 and
the other two being contained within body section 21, and with the
slips carried by each body section having vertical end faces 42
which lie approximately in the vertical plane of separation 22 of
the two halves of the unit. The vertical surfaces of the two body
sections which meet in this plane are represented at 43' in FIG. 4.
At their radially outer sides, slips 41 have downwardly tapering
frustoconical wedge surfaces 43, 44, and 45 which engage
correspondingly shaped wedge surfaces 46, 47, and 48 (FIG. 5) on
the body sections 20 and 21, to cam or wedge the slips radially
inwardly relative to the body section upon downward movement of the
slips, and thus support the casing. Preferably, the camming
surfaces on the slips and body sections are formed in stepped
fashion, as seen in FIG. 5, so that when the slips are moved
upwardly a relatively short distance to the FIG. 7 inactive
position, the stepped interfitting relationship between the slips
and body sections enables the slips to move radially outwardly far
enough to allow movement of the entire assembly upwardly past the
upper end of the casing.
Each of the slips 41 is suspended by an individual hanger 49 (FIGS.
5, 7, 8, and 13), which as seen best in FIG. 13 has a horizontal
base portion 50 secured by screws 51 to the upper surface 42 of the
slip. Two parallel vertical portions 52 of the bracket project
upwardly in spaced relation, and may be interconnected by a cross
web 53. Above web 53, the upstanding portions 52 of bracket 49 form
a recess or guideway 54 defined by two parallel planar inner
surfaces 55 lying in planes which are parallel to and spaced
equally in opposite directions from a vertical diametrical plane 56
containing the main vertical axis 12 of the tool. Also, as seen
best in FIGS. 5 and 7, the two upstanding portions 52 preferably
extend angularly radially outwardly as they advance upwardly above
a location 57' near the level of cross web 53.
For slip supporting coaction with the brackets 49 of the various
slips 41, there are provided a number of support posts or columns
57 mounted by the body sections 20 and 21 for upward and downward
movement relative thereto. Each of these posts 57 is externally
cylindrical and centered about a vertical axis 58 extending
parallel to main vertical axis 12. The four axes 58 of the four
posts 57 are equally spaced circularly about axis 12, with two of
the posts being carried by body section 20, and the other two posts
being carried by body section 21, as seen best in FIG. 4. Each of
the posts 57 is received telescopically within a coacting vertical
cylindrical passage or guideway 59 in the corresponding body
section, and is a sufficiently close fit in that passage to
effectively guide the post for only vertical movement. If desired,
a portion or all of the passage 59 may be lined by an appropriate
bushing 60 to enhance the effectiveness of the mounting of the
post. A coil spring 61 is contained within the lower portion of
each of the passages 59, and is seated at its lower end on a
reduced diameter shoulder portion 62 of passage 59, so that the
spring yieldingly urges the associated post 57 upwardly from the
FIG. 5 position toward a position just short of or under the FIG. 7
setting of the post. The force of each spring 60 is just sufficient
to overcome the weight of the associated slip 41, bracket 59, and
the bracket engaging structure carried at the upper end of the
post.
That bracket engaging structure at the upper end of each post
includes a head element 63, which is appropriately rigidly
connected to the upper end of the associated post 57, as by
providing head 63 with a vertical cylindrical passage 64 in which
the upper end of the post is a tight forced or friction fit holding
the parts in the illustrated assembled relation. In extending
upwardly from the lower horizontal undersurface 65 of head 63, this
part may be of square cross section, up to the level 66 of FIG. 5,
to have a planar vertical radially inner surface 67 and a parallel
planar vertical radially outer surface 68, both of which are
perpendicular to the previously mentioned radially extending
vertical plane 56. Projecting radially outwardly from surface 68,
each of the heads 63 has a roller 70 mounted to turn relative to
head 63 about a horizontal axis 71 (FIG. 5) which lies in the plane
56 of FIG. 5a. This roller 70 is received and closely confined
within a vertical guideway 72 in an upstanding bifurcated guide
element 73 projecting upwardly from a horizontal plate 74 secured
rigidly to the upper surface 75 of the corresponding one of the two
body sections 20 or 21. The vertical guideway 72 thus guides roller
70 for only vertical movement, and thereby prevents post 57 from
turning about its axis 58 upon upward movement of the post and
carried structure.
At its upper end, each of the post carried head elements 63 has a
generally radially inwardly projecting arm 76, having parallel
planar opposite side faces 77 which lie in two vertical planes
parallel to the plane 56 of FIG. 13 and spaced very slightly from
surfaces 55 of bracket 49, to allow movement of bracket 49 radially
inwardly and outwardly relative to main axis 12 and relative to the
post carried head element 63. To further guide each of the slip
mounting brackets 49 and the associated slip for such essentially
radial movement relative to axis 12, the spaced upper portions 52'
of the bracket 49 carry at their inner sides two pairs of guide
rollers 78, with one of the pairs being carried by each of the
projections 52' and with these rollers turning about two axes 79
and 80 as seen in FIGS. 5 and 13. These rollers are received and
confined within two parallel coacting track guideways 81 formed in
the opposite sides of arm 76 of head element 63, to hold each
bracket 49 and carried slip 41 in a fixed orientation with respect
to the corresponding post 57 while guiding the bracket and slip for
its generally radial movement. As seen clearly in FIGS. 5 and 7,
the tracks 81 are inclined slightly, and the axes 79 and 80 of the
rollers 78 are correspondingly offset vertically as well as
horizontally, to guide the brackets and slips for movement along
slightly inclined paths which advance downwardly as the slips move
radially outwardly. As a result, when the posts 57 and carried
parts are elevated upwardly above the FIG. 5 position and toward
the FIG. 7 position, the weight of the slips will by gravity cause
the slips and their brackets 49 to move radially outwardly to their
laterally retracted positions of FIG. 7. Conversely, when the slips
are supported by the body sections 20 and 21 upon downward movement
of posts 57, the inclined tracks tend to assist the outer cam faces
43, 44, etc. in camming the slips radially inwardly.
To actuate the various posts 57 and carried slips upwardly and
downwardly in unison, I provide an annular cam structure 82
centered about and mounted to move circularly about main axis 12.
This cam ring structure 82 is desirably formed as two identical
semicircular sections 83 and 84 (see FIG. 4). As best seen in FIG.
4, section 83 has a first end face 85 and a second diametrically
opposite end face 86, while section 84 has two similar and closely
adjacent end faces 87 and 88. In the FIG. 4 active setting of the
slips, these end faces 85, 86, 87, and 88 of the two cam sections
lie in an axial plane 89 which is offset circularly from the
previously discussed plane of separation 22 of the two body
sections. When, however, the cam structure is turned about axis 12
to the retracted-slip setting of FIGS. 6 and 7, the end faces 85,
86, 87, and 88 of the cam sections all lie essentially in the
discussed plane of body section separation 22, so that the cam
sections as well as the remainder of the apparatus can be swung to
the open condition shown in broken lines in FIG. 3.
The two cam sections 83 and 84 are actuable in unison between their
discussed different settings of FIGS. 4 and 6 by means of two power
actuated units, preferably taking the form of two piston and
cylinder mechanisms 89 carried by the two body sections 20 and 21
respectively. More particularly, the cylinder of each of the
mechanisms 89 may be secured pivotally at 90 to a portion of the
previously mentioned plate 74 carried by one of the body sections,
while the piston rod of that mechanism 89 may be secured pivotally
at 91 to a portion of the associated cam section 83 or 84. An
appropriate control valve diagrammatically represented at 92 in
FIG. 4 supplies pressurized fluid to the two piston and cylinder
mechanisms 89 simultaneously to actuate them at the same time in
either desired direction.
The cam sections 83 and 84 are appropriately guided for only
circular movement about axis 12, as by suitable roller type
bearings mounted rotatably to the body carried plates 74. More
specifically, each of the plates 74 may carry several circularly
spaced rollers 93 (FIG. 11) at the underside of the associated cam
section 83 or 84, received and confined within an arcuate bottom
recess or guideway 94 in that cam section, and may also carry a
second group of circularly spaced rollers 95 for engaging an
arcuate guide surface 96 formed at the upper side of a flange 97 on
the corresponding cam section 83 or 84. The rollers 93 turn about
horizontal axes 98 which extend radially outwardly from the main
vertical axis 12 of the tool, while rollers 95 turn about vertical
axes 99, and have inclined annular frustoconical bearing surfaces
100 engaging the correspondingly inclined surfaces 96 on the cam
sections.
In order to effect upward and downward movement of posts 57 and the
carried slips in response to arcuate movement of the cam sections
83 and 84 about axis 12, the cam sections are provided with four
camming slots or guideways 101 (FIGS. 5, 7, 9, and 10), which
receive four cam follower rollers 102 mounted rotatably to the four
head elements 63 carried by the four posts 57 respectively. Each of
these rollers 102 may turn about the corresponding radial axis 56
of FIG. 5a, and project radially inwardly from the inner surface 67
of the corresponding head 63. As seen best in FIGS. 9 and 10, each
cam slot 101 has a camming surface 103 defining the upper side or
edge of the slot and which is inclined to advance vertically as it
advances arcuately about axis 12, upon arcuate movement of cams 83
and 84 from the FIG. 10 position to the FIG. 9 position, each
roller 102 engages the corresponding cam surface 103 and is
deflected downwardly thereby, against the resistance offered by the
associated spring 61, to thus cause downward shifting move-ment of
the slips in response to predetermined arcuate movement of the cam
sections. As seen clearly in FIG. 9, surface 103 has two portions
of different inclination, including a first portion of relatively
great inclination from point 203 to point 303, and a second and
preferably shorter portion of reduced inclination from point 303 to
the extremity 403 of the slot. Thus, the slips are first cammed
downwardly at a relatively rapid rate, with resultant rapid
radially inward movement of the slips, and are then cammed very
slowly downwardly and inwardly as the follower moves along the
reduced inclination surface to the final pipe gripping position of
FIG. 9. The initial rapid movement allows for positive forced
centering of the pipe by the slips, even though the pipe may
initially be offset a substantial distance from a properly centered
position of alignment with the well axis, while the final slow
movement permits a more gradual but still positive and forced
ultimate setting of the slips into gripping contact with the
pipe.
In the FIG. 10 retracted setting of the slips, each cam follower
102 is received within a shallow detenting notch 105 formed in an
upwardly facing horizontal surface 106 which merges with the
inclined bottom edge wall 206 of the corresponding slot 101. As
will be apparent, springs 60 urge the slips and cam followers 102
upwardly only to approximately the level of the follower 102 in
FIG. 10, so that the weight of the slips and associated parts can
maintain the followers 102 in detenting positions within notches
105.
To protect the working parts of the tool, the body sections may
carry two complementary essentially semicircular covers 107,
secured by bolts 108 to the top of the body sections, and meeting
in the previously mentioned plane of separation 22. The inner edges
of these covers may carry two semicircular complementary flange
elements defining together an opening dimensioned to receive the
well casing 11, and to pass its upper enlarged tool joint end.
To now describe a cycle of use of the tool, assume that the
apparatus is initially in the completely assembled condition
illustrated in the figures, and that the slips and their actuating
parts are in the retracted positions of FIGS. 6, 7, and 10. In this
condition, the tool can be moved downwardly past the upper end of
well pipe 11 and to the FIG. 1 position. When in that position, an
operator actuates control valve 92 to cause the piston and cylinder
mechanisms to move cam sections 83 and 84 arcuately and at an
essentially uniform rate from their FIG. 6 positions to their FIG.
4 positions, to thereby move the cam slots 101 between their FIG.
10 and FIG. 9 settings. This actuation of the cam sections causes
the cam follower rollers 102 to move downwardly to their FIG. 9
positions, to thus actuate each of the posts 57 downwardly against
the tendency of the associated spring 61 and to the FIG. 5 setting,
with resultant lowering of the slips and forced inward deflection
thereof, first rapidly for centering and then more slowly for final
setting, to their active positions of gripping engagement with the
well pipe. As the posts and slips move downwardly, the inclined
surfaces 43, 44, 45, 46, 47, and 48 on the slips and body sections
cam the slips radially inwardly, with rollers 78 of hangers 49
enhancing this effect and moving radially inwardly along guideway
tracks 81 of post carried head elements 63 from the FIG. 7 position
to the FIG. 5 position of the hangers. When the slips have thus
been engaged with the casing 11, the casing can be moved upwardly
or downwardly as desired to add or subtract a length of pipe by
actuation of the suspending hoist mechanism 14. In the FIG. 9
position of the cam mechanism, in which the slips are set tightly
against the casing, the cam follower rollers are not normally at
the end of their range of possible movement beyond points 303, but
rather have remaining and unused space for overtraveling movement
beyond that set position, in order to allow for effective gripping
of pipes of different external diameters.
When it is desired to release the casing from the support unit 10,
the operator actuates the control valve to move the cam sections
arcuately back to the setting of FIGS. 6, 7, and 10, to return the
posts and carried parts back upwardly to the FIG. 7 position, with
resultant automatic radially outward retraction of the slips by
gravity as the hanger rollers 78 move outwardly along the inclined
guideway tracks 81. Engagement of the cam followers 102 with
inclined surfaces 206 of the slots cams the followers and slips
upwardly in a positive manner during such slip releasing
actuation.
If it becomes necessary at any time to remove the tool laterally
from about the pipe, the slips are actuated to their retracted
positions, the two pins 33 and one of the pins 25 are removed as
previously described, and the entire assembly may then be swung
open to the broken line position of FIG. 3.
While a certain specific embodiment of the present invention has
been disclosed as typical, the invention is of course not limited
to this particular form, but rather is applicable broadly to all
such variations as fall within the scope of the appended
claims.
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