U.S. patent application number 12/918290 was filed with the patent office on 2011-05-19 for grip head for an earth boring unit.
Invention is credited to Dietmar Scheider.
Application Number | 20110114391 12/918290 |
Document ID | / |
Family ID | 41130870 |
Filed Date | 2011-05-19 |
United States Patent
Application |
20110114391 |
Kind Code |
A1 |
Scheider; Dietmar |
May 19, 2011 |
GRIP HEAD FOR AN EARTH BORING UNIT
Abstract
The invention relates to a grip head for an earth boring unit,
comprising a hollow shaft (3), wherein a sleeve (1) is arranged
coaxially on the hollow shaft (3) to slide relative thereto, said
sleeve having at least one end region (1b) widening particularly at
the bottom thereof particularly in the form of a cone and at least
two clamp jaws (2) which can be displaced radially relative to the
hollow shaft (3) are arranged in the hollow shaft (3) and/or on the
sleeve (1), comprising stop faces (2b) cooperating with the
widening end region (1b), such that on movement of the end region
(1b) over the clamp jaws (2) said jaws may be pressed inwards and a
first tensioning mechanism and form a first tensioning device for
an upper end of a casing (9) which may be introduced from below
into the sleeve, in particular such that a cooperation between
clamp jaws (2) and casing (9) permits transmission of a torque
between ween the hollow shaft (3) and casing (9) and a second
tensioning mechanism is provided in the hollow shaft (3), by means
of which the introduced/introducible casing (9) may be fixed at the
upper rend region thereof in the axial direction, in particular
fixing a casing (9) in the axial direction against gravity relative
to the grip head, wherein a flush tube (14) of supplying a flushing
fluid is arranged coaxially in the hollow shaft (3) and fixed in
rotation relative thereto the lower region of which is enclosed by
an annular balloon (11) which may be pumped up with a fluid, in
particular a liquid.
Inventors: |
Scheider; Dietmar; (Voerde,
DE) |
Family ID: |
41130870 |
Appl. No.: |
12/918290 |
Filed: |
April 29, 2009 |
PCT Filed: |
April 29, 2009 |
PCT NO: |
PCT/EP09/03100 |
371 Date: |
September 7, 2010 |
Current U.S.
Class: |
175/423 |
Current CPC
Class: |
E21B 19/07 20130101;
E21B 21/106 20130101; E21B 7/20 20130101; E21B 3/02 20130101 |
Class at
Publication: |
175/423 |
International
Class: |
E21B 19/10 20060101
E21B019/10; E21B 19/08 20060101 E21B019/08; E21B 21/00 20060101
E21B021/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2008 |
DE |
10 2008 021 491.4 |
Claims
1. A grip head for an earth-drilling system, the grip head
comprising a tube, a sleeve provided coaxially on the tube so as to
move relative thereto and having a downwardly frustoconically
widening lower end, at least two jaws supported in the tube on the
sleeve so as to move radially but not angularly relative to the
tube, the jaws having radially outer ends having abutment faces
that interact with the widening lower end such that by sliding the
lower end over the jaws they are pressed radially inward and form
first grab means for an upper end of a casing that is
insertable/inserted into the sleeve for transmitting torque between
the jaws and the casing and thus between the tube and the casing,
second grab means provided in the tube for securing the casing
axially at its upper end so as to hold the casing stationary
axially against gravity relative to the grip head, a circulation
pipe for the delivery of a drilling mud extending coaxially in the
tube and rotationally fixed thereto, an annular bladder inflatable
by a fluid surrounding the lower end of the pipe, and means
connected to the bladder for inflating it with a fluid and thereby
sealing an annular space between the casing and the tube for
preventing upward escape of drilling mud from inside the casing
through the grip head.
2. The grip head according to claim 1, wherein the second grab
means is actuatable by moving the sleeve.
3. The grip head according to claim 1, wherein the sleeve for
actuating the first grab means is movable relative to the tube by a
first drive and the second grab means is actuatable by a second
drive independent of the first drive, both drives being attached to
a common support element.
4. (canceled)
5. The grip head according to claim 1 wherein the annular bladder
is composed of a flexible elastic material.
6. The grip head according to claim 1 wherein the bladder is
attached to the circulation pipe.
7. The grip head according to claim 1, wherein the bladder has a
fluid supply line supplied with the fluid from a rotary feedthrough
fitting attached to the circulation pipe, in particular an inner
annular part that is rotationally fixed to the circulation pipe,
and is connected to the fluid supply line, and has an inner annular
part that is rotationally fixed relative to a surrounding machine
assembly, and by which fluid is able to be supplied to the inner
annular part.
8. The grip head according to claim 7, claim 7, wherein the rotary
feedthrough fitting has three fluid conduits, wherein one fluid
conduit is provided for the fluid supply line to the bladder, and
two fluid conduits are provided for delivery of fluid to at least
one each of two cylinder-piston units for axial movement of the
sleeve on the tube in opposite directions.
9. The grip head according to claim 1, wherein the second grab
means comprises at least two inner wedges each of which has a
radially outwardly directed guide face that interacts with a guide
face provided inside the tube with the result that radial inward
movement is effected by moving a inner wedge axially downward.
10. The grip head according to claim 1, wherein the inner wedges
each have a radially inwardly directed frustoconical contact face
formed as a shoulder or step, by which they can each be applied
radially with positive engagement to an upper end of a casing.
11. The grip head according to claim 10, wherein the shoulder or
step is of right-angled shape formed by a collar that surrounds the
upper end of the casing a lower end face of the collar forming the
shoulder or step.
Description
[0001] The invention relates to a grip head for earth-drilling
system, comprising
[0002] a tube,
[0003] a sleeve provided coaxially on the tube so as to move
relative thereto and having at least one lower end, in particular
one widening downward, in particular widening in a frustoconical
shape,
[0004] at least two jaws supported in the tube and/or on the sleeve
so as to move radially relative to the tube, the jaws at their
radially outer ends having abutment faces that interact with the
widening lower end such that by sliding the lower end over the jaws
they are pressed radially inward and form first grab means for an
upper end of a casing that is insertable/inserted into the sleeve,
in particular in such a way that due to the interaction between the
jaws and the casing torque can be transmitted between the tube and
the casing, and
[0005] second grab means provided in the tube for securing an
inserted/insertable casing axially at its upper end, in particular
so as to hold the casing stationary axially against gravity
relative to the grip head.
[0006] A grip head of this type for use in well boreholes has
already been disclosed by the instant applicant in German patent
application DE 10 2008 012 729.9. The grip head described there,
for which the interaction with a drill pipe was described, is in
principle also capable of accommodating a casing, such as that
described above, in place of a drill pipe.
[0007] Provision can be made in a first possible embodiment whereby
the second grab means, just like the first grab means, is able to
be actuated by moving the sleeve that is movable on the tube. This
has the advantage for example that only one drive must be provided
to move the sleeve.
[0008] In an alternative design, provision can also be made whereby
the sleeve for actuating the first grab means is movable relative
to the tube by a first drive, in particular a hydraulic drive, and
the second grab means is actuatable by a second drive independent
of the first drive, in particular where both drives are attached at
one side to a common support element. As a result, both grab means
can be operated independently of each other, for example either
sequentially, but also simultaneously, for example, by
synchronization in a master control unit that controls the drives.
In both embodiments here, the drives can comprise, for example at
least one, preferably, multiple cylinder-piston units distributed
uniformly within the tube.
[0009] In the prior art, so-called casings have been used in
connection with implementing well boreholes for the purpose of
stabilizing the walls of the well borehole after drilling and after
the drill pipe has been lifted out. To this end, provision is
accordingly made whereby the casing is inserted into the bore
created. The casing itself is hollow so that the inner free
diameter of the bore is maintained; however, a long-term
stabilization of the borehole is effectuated by the casing
wall.
[0010] A problem is known in the prior art whereby well boreholes
do not always follow a straight path, with the result that it is
sometimes difficult to insert a casing into the borehole created in
the ground after the dill pipe has been lifted out.
[0011] The object of the invention is thus to provide a grip head
of the type described above that offers the ability to insert a
casing into existing well boreholes in the ground at a later point
in time, and in so doing to enable the casing not only to be
inserted but also, in particular to be screwed into the borehole.
In order here to achieve a facilitated insertion of the casing into
the borehole, an additional goal is to use drilling mud, in
particular water as a fluid, such that a concentration of the
circulating force of the drilling mud within the borehole can be
achieved.
[0012] This object is attained according to the invention by an
approach wherein a circulation pipe for the delivery of a drilling
mud extends coaxially in the tube and is rotationally fixed
thereto, the lower end of the pipe being surrounded by an annular
bladder inflatable in particular by a fluid.
[0013] The essential core idea in the construction of the grip head
according to the invention is that a casing inserted in the grip
head can be clamped securely first of all by the two grab means
described above, and in particular by the movable jaws whose radial
displacement clamps a casing inserted into the grip head securely
in place so as to cause the casing in the ground to also rotate by
rotation of the grip head. The above-referenced second grab means
ensures here that an upper end, in particular of the casing, is
held surely in place in the grip head, in particular against the
force of gravity, so as to prevent the casing from sliding out of
the grip head axially of the casing.
[0014] As was already described in the above-referenced document DE
10 2008 012 729.9, this makes it possible to rotationally insert a
casing into the ground with the grip head in a manner analogous to
the drill pipe described in the above-referenced document, where
now in this embodiment according to the invention the ability is
provided by the coaxial arrangement of the circulation pipe within
an inserted or insertable casing to pump in drilling mud through
the circulation pipe into the casing, such that the fluid moves
through the casing down to its lower end, and in a region between
the outer wall of the casing and the inner wall of the borehole
contributes to loosening the borehole wall, to a kind of
lubricating effect, and thus to an easier insertion of the casing
into the borehole.
[0015] In order to achieve a good effective engagement between the
jaws and a casing, the jaws of the first grab means can have, for
example a surface formation on the face engaging the casing. For
example, the surface can have a structuring, and/or a preferably a
coating, that functions like a friction lining. This type of
coating can for example have particles, for example sand, diamonds,
etc., that enhance the effective engagement. As a result, the force
can be applied over a large surface area to the casing, thereby
avoiding any local damage.
[0016] According to the invention, a seal can be achieved here
between the circulation pipe and the casing by the inflatable
bladder that extends annularly around the circulation pipe in a
region between circulation pipe and an inner wall of the casing,
thereby preventing the drilling mud pumped in at high pressure from
escaping upward through the grip head.
[0017] In order to ensure this, provision can be made in a
preferred embodiment whereby in response to inflating the bladder
an annular space is sealed off to the drilling mud that is formed
between the circulation pipe and an introduced casing coaxially
surrounding the circulation pipe. What is preferably achieved by
the inflating action is that the bladder increases in volume,
continues to inflate, and thus contacts the inner surface of the
casing wall and the outer surface of the circulation pipe wall,
thereby sealing this annular space in a pressure-tight fashion.
Here the seal against circulating pressures of varying levels can
be achieved, in particular by the pressure used to inflate the
bladder. In terms of the fluid to be pumped into the bladder,
water, for example can be used; however, preferably, a hydraulic
fluid, in particular an oil is used.
[0018] In order to enable this inflation, provision is made in a
preferred embodiment whereby the annular bladder is composed of a
flexible, in particular elastic material. The flexibility ensures
that when inflated the bladder automatically adjusts to the shapes
that exist in the annular space between circulation pipe and
casing.
[0019] In addition, the preferred elasticity of the bladder ensures
that fluid pumped into the bladder also automatically then escapes
from the bladder due to the fact that the inflated elastic material
tends to contract and thus force the pumped-in fluid out of the
bladder.
[0020] Provision can, however, also be made whereby the fluid for
inflation is not only pumped into the bladder but the fluid is also
pumped out of the bladder to relieve the pressure. Both for pumping
to inflate, and optionally pumping the fluid out, a separate pump
can be used, but also a pump that is employed in any case for an
earth-drilling system having this type of grip head according to
the invention.
[0021] Provision can be made in another preferred embodiment
whereby the bladder is attached to the circulation pipe, thereby
preventing the bladder from moving axially relative to the
circulation pipe, in particular when not inflated. The attachment
thus always achieves the optimum position relative to the
circulation pipe and relative to an inserted casing. In particular
the attachment can be selected so that the bladder is above the
lower end of the circulation pipe and simultaneously relative to a
casing inserted into the grip head below the upper end of the
casing.
[0022] In an embodiment according to the invention, the bladder has
a fluid supply line that is able to be supplied with fluid from a
rotary feedthrough fitting attached to the circulation pipe. For
example, this rotary feedthrough fitting can have an inner
fluid-conducting annular part that is rotationally fixed to the
circulation pipe and is connected do the fluid supply line, and has
an outer fluid-conducting annular part rotatable relative to the
inner annular part, which is rotationally fixed to a surrounding
machine assembly and through which fluid is supplied to the inner
annular part when the annular parts rotate relative to each
other.
[0023] This ensures that no twisting of the fluid supply line
occurs around the circulation pipe or relative to the grip head
when the grip head rotates so as to drill a casing into the ground
since the fluid supply line extends between the bladder and a part
of the rotary feedthrough fitting that is rotationally fixed to the
circulation pipe with the result that the fluid supply line rotates
together with rotation of the grip head.
[0024] The delivery of fluid to the rotary feedthrough fitting and
then to the bladder can be effected by a surrounding machine
assembly through an outer rotatable annular part on the feedthrough
fitting, this part being rotationally fixed relative to the
surrounding machine assembly, where here too the rotational
decoupling between outer and inner annular parts ensures that the
delivery to the rotary feedthrough fitting and its outer annular
part does not experience any twisting in response to rotation of a
grip head relative to a surrounding machine assembly.
[0025] A preferred development of the rotary feedthrough fitting
can provide that this feedthrough fitting has three fluid conduits;
in particular three rotary feedthrough fittings are thus
technically implemented in one part. Accordingly, the ability is
thus created by this rotary feedthrough fitting to deliver three
different working fluids independently from the outside, i.e. from
a surrounding machine assembly, to a rotating grip head. For
example, provision can for example be made whereby one fluid
conduit handles the fluid supply line and/or fluid discharge to
and/or from the bladder, where two other fluid conduits are used to
deliver fluid to at least one cylinder-piston unit each for axial
movement of the sleeve on the tube in opposite directions.
[0026] For example, actuation of the grab means of the grip head
can be effected by movement of the movable sleeve relative to the
tube, where at least one cylinder-piston unit is provided to
actuate the sleeve for movement axially for each of the two
possible directions. Thus, at least one cylinder-piston unit can be
used to move the sleeve downward relative to the tube, and at least
one other can be used to move the sleeve upward relative to the
tube. Each of these cylinder-piston units can receive its working
fluid from one of the conduits of the above-referenced rotary
feedthrough fitting. The ability thus exists to deliver all
requisite working fluids to the grip head according to the
invention using only a single rotary feedthrough fitting.
[0027] An embodiment of the invention is illustrated in detail in
the following FIGURE.
[0028] FIG. 1 here provides a schematic sectional view of a grip
head according to the invention that comprises a tube 3 on which is
coaxially mounted a sleeve 1, a so-called a grip head cap whose
lower end widens downward in a frustoconical funnel shape. The
inner wall region of this downwardly flared lower end of the
movable sleeve forms actuating surfaces for radially outer ends or
abutment faces of jaws 2 that are thus automatically moved radially
inward by axial downward movement of the sleeve. These clamping
jaws 2 can be movably mounted on the sleeve 1 and/or on the tube
3.
[0029] FIG. 1 shows a casing 9 inserted in the grip head according
to the invention, where the jaws 2 bear radially inward on the
outer surface of the casing 9 due to the downward displacement of
the outer sleeve 1 and create a frictional and/or nonpositive
engagement. This creates the ability to transmit torque to the
casing 9 by rotating the entire grip head according to the
invention to insert the casing by rotation into a borehole.
[0030] FIG. 1 furthermore shows second grab means that is formed by
multiple inner wedges 4 arranged around the casing 9, where each
inner wedge 4 has a radially outwardly directed guide face 4a that
bears on a radially inwardly directed guide face 3a formed in the
tube 3, thereby enabling radial movement of the inner wedges, in
particular inward, to be effected by moving the respective inner
wedge 4 axially, in particular downward.
[0031] As mentioned above, the individual inner wedges 4 of the
second grab means are moved when the sleeve 1 outside the tube 3
moves axially downward, in particular in the normal working
position. To this end, a mechanical linkage is provided that
extends, for example, through the wall of the tube 3 between the
outer sleeve 1 and inner wedges 4.
[0032] This ensures that, when the outer sleeve 1 is moved on the
tube 3, the inner wedges 4 on the tube 3 are entrained to move in
the same direction at least to a limited extent.
[0033] The relative orientation of the guide faces 3a and 4a of the
tube 3 and of the inner wedges 4 here has the effect that axial
movement automatically causes radial movement of the inner wedges 4
such that they bear in positive engagement against the casing 9
enclosed by the tube.
[0034] The kinematic translation of an axial movement effected by
the inner wedges 4 into a radial inward movement can be effected
here, for example, in that the engaged guide faces 3a and 4a on the
inner wedges 4 and the tube 3 are inclined relative to the central
axis of the tube 3, in particular are at an acute angle thereto
when viewed in cross-section.
[0035] A positive engagement between the inner wedges 4 and the
casing 9 can be achieved here by contact faces 4b that are provided
on the inner wedges 4 and their radial inner end faces that are
shaped complementarily to the casing 9, in particular at their
upper ends, for example, to the diameter of the casing 9, with the
result that these contact faces 4b, have for example at least one
cylindrical-section-type surface region, and/or can also be formed
with a shoulder 9a that fits with the casing, or have a step 9a at
which the diameter of the casing changes, in particular is reduced
from top to bottom.
[0036] This reduction at the referenced shoulder or step 9a can be
effected, for example, by a right-angle step relative to the axis
of the casing, or also by a conical step or possible other shapes.
Accordingly, the contact faces 4b of inner wedges 4 have portions
that are adapted to this type of shoulder or step 9a, thereby
enabling an axial lifting force or retaining force to be exerted on
the casing by positive engagement between the inner wedges 4 and
the casing 9, due to the fit of the inner wedges 4 with this
shoulder or step 9a when the contact face 4b engages the shoulder
or step 9a without the inner wedges 4 sliding axially relative to
the casing 9.
[0037] In order to form the guide face 3a as an opposing surface
for those guide faces 4a on each inner wedge 4, provision can be
made in the embodiment shown here whereby this guide face is formed
inside the tube 3 by a radially inwardly projecting annular ridge
3b whose inner periphery forms a frustoconical inner face that is
coaxial to a central axis M of the tube 3, in particular such that
this frustoconical inner face tapers downward in the normal working
position of the grip head. It is specifically this downward taper
that achieves the result that movement of these inner wedges 4
radially inward is effected in response to their downward movement
in the grip head when the guide faces 4a of the inner wedge 4 slide
along the frustoconical inner face 3a of the annular ridge 3b.
[0038] The design of a frustoconical inner face on the inner
annular ridge inside the tube has advantages in terms production
engineering since this type of frustoconical inner face can be
easily effectuated by internally turning out a shaft. To this end,
for example, a the tube 3 can be produced from a solid
material.
[0039] The radially outwardly directed guide faces 4a of inner
wedges 4 can furthermore be designed as outer conical outer surface
regions corresponding to the frustoconical inner face. This is the
result when both guide faces 4a on inner wedges 4 as well as those
on the projecting annular ridge are of frustoconical shape, or form
a section of a frustoconical inner face, such that there is only
one specific position at which respective guide faces 4a of inner
wedge 4 and annular ridge 3b contact each other in positive
engagement since outside this specific position the respective
diameters of the individual conical surfaces do not match each
other relative to central axis M of the tube 3.
[0040] Provision is therefore made in a preferred embodiment
whereby the guide faces 3a and 4a of inner wedge 4 and annular
ridge 3b are complementary to each other in such a way that the
positive surface-contact engagement between these guide faces
increases with increasing positive engagement between inner wedges
4 and the casing 9, that is, in particular when the inner wedges 4
are pushed downward and simultaneously inward by the sleeve 3.
[0041] The second grab means can thus be implemented such that at
the moment when an optimal positive engagement exists between the
inner wedges 4 and the casing 9 an optimal positive engagement is
also present between the guide faces 3a and 4a. In this way, forces
are optimally transmitted between the surfaces while avoiding high
local loads. This embodiment furthermore has the advantage that
when no positive engagement yet exists between the inner wedge 4
and the casing 9, or between the respective guide faces, these
guide faces do not contact each other over their entire surface
areas but only at certain points or linearly, thereby reducing
friction between the guide faces in this position of the inner
wedges.
[0042] The same design can also be provided between the guide faces
on the jaws 2 of the first grab means and the conically widening
lower end of the outer sleeve 1. All of the above-mentioned
embodiments in terms of construction of the guide faces between the
inner wedges of the second grab means and the frustoconical inner
face of the annular ridge also apply analogously to the jaws 2 of
the first grab means and the frustoconical downwardly flaring end
of the sleeve 1.
[0043] In this embodiment, provision can furthermore be made
whereby one inner wedge 4 is movable axially on a bolt 6 extending
parallel to but offset from the tube axis M and passing through the
one inner wedge 4 or a projection extending radially therefrom.
This has the advantage when multiple individual inner wedges 4 are
used these elements are guided and can move only axially along this
guide inside the tube 3.
[0044] As a result, for example, any tilting of the inner wedges 4
relative to the casing 9 is prevented. In order to enable an
approach where, in addition to the guided axial movement, at the
same time radial movement, in particular inwardly, is possible, the
bolt 6 is located in a slot of the inner wedge 4 or its
above-referenced projection that is elongated radially, in other
words, for example, analogously to a radially elongated slot. As a
result, given axial movement of the inner wedge 4 it can be guided
axially along the bolt 6 and can simultaneously move radially
perpendicular to the axial extent of the bolt 6.
[0045] As mentioned above, provision is made according to the
invention whereby inner wedges 4 are actuated by movement of the
outer sleeve 1. To this end, a linkage can be provided from inside
the tube 3 to outside the sleeve 1. In the embodiment shown, the
inner wedges 4 here are movable axially, in particular in the
direction of increasing positive bearing on the casing by an
actuating element 5 provided inside the tube 3, the actuating
element 5 being connected to the sleeve 1 outside the tube by at
least one radial link that extends through an slot 3c in the tube
3.
[0046] Provision is preferably made here whereby this slot 3c is
elongated axially of the tube 3 so that in response to axial
movement of the sleeve 1a link that extends radially through this
slot 3c can shift axially in the slot 3c. As a result, movement of
the sleeve 1 outside the tube 3 can be transmitted into the tube 3
due to the fact that the actuating element 5 connected by the links
moves together with the sleeve 1. The movement of the actuating
element 5 can thus be transmitted in various ways to inner wedges
4, for example by having the actuating element 5 act directly and
immediately on the inner wedges 4 or by having the actuating
element 5 act indirectly through intermediate elements on the inner
wedges 4.
[0047] Independently of the manner of this action, provision can be
made here in a preferred embodiment whereby the actuating element 5
is a ring with a central hole surrounding the casing, and with all
the inner wedges 4 movable this actuating element 5.
[0048] Provision can furthermore be made whereby the
above-referenced bolts 6, along which the inner wedges 4 move, are
attached to the actuating element 5. For example, attachment can be
effected by a screw connection, or the bolts 6 can extend in guide
holes provided on the annular ridge 3b formed in the tube and
forming the frustoconical outer guide face. The bolts 6 here
angularly equispaced around and radially equispaced from the
central axis M, as are the respective inner wedges 4 that are
movably mounted thereon.
[0049] In another preferred embodiment, at least one of the inner
wedges 4, in particular each inner wedge in the tube 3, can be
biased against a resetting force in the direction of increasing
positive engagement and thus, in particular in a downward direction
in terms of the normal working position. This resetting force can
be exerted, for example, by a compression spring 7, in particular
one that is supported at one end, in particular at its lower end,
on the respective inner wedge 4, and is supported at its opposite
end, in particular at its upper end, on the annular ridge mentioned
above. This compression spring 7 can surround the respective bolt
6, also referenced above.
[0050] The movement by the inner wedges 4 in the direction of
increasing positive engagement against a resetting force has the
advantage that the inner wedges 4 can be pressed axially against a
shoulder or step 9a formed on the casing by this resetting force.
This produces the effect whereby, at the moment when the casing
releases the inner wedges 4, the inner and outer guide faces are
moved out of engagement by the resetting force, in other words, are
shifted upward for example, relative to the normal working
position. As a result, the casing is released from the inner wedges
4. This type of release between the casing 9 and the inner wedge 4
can be effected, for example when the casing 9 is inserted into the
ground and the grip head moves downward relative to the casing 9
away from shoulder 9a of the casing 9a axially of the casing 9.
[0051] In the embodiment shown here, which can also be dispensed
with, provision is made whereby an indirect action by actuating
element 5 on respective inner wedges 4 is implemented by at least
one compression spring 8 that is provided between the actuating
element 5 and the inner wedges 4. This achieves the effect that a
force does not act directly between the actuating element and the
inner wedges but the force instead is applied in each case by a
respective one of the compression springs 8. This has the
additional advantage that essentially the same force is always
exerted on each inner wedge 4 through a given specified axial
travel, the force being produced by the spring constant of the
respective compression spring 8 as a function of the compression
travel.
[0052] In an embodiment not shown here, provision is made whereby
this type of compression spring 8 is disposed directly between
actuating element 5 and inner wedge 4, or, on the other hand, in an
especially preferred embodiment shown here, whereby this type of
compression spring 8 is disposed between an actuating element 5 and
an intermediate element 5a, for example an intermediate ring 5a
located between the actuating element 5 and the inner wedges 4. All
the inner wedges 4 can in turn be contacted through this
intermediate ring 5a. The spring elements 8 can accordingly be
provided between the annular end faces of the intermediate ring 5a
and the actuating element 5, for example, preferably where the
above-referenced bolts 6 extend starting from actuating element 5
through intermediate ring 5a and inner wedges 4. For example, each
of these springs 8 can thus surround a respective one of the bolts
6.
[0053] This embodiment has the particular advantage according to
the invention that the sleeve 1 is movable axially relative to the
tube 3, where initially the inner wedges 4 are movable into a
positive engagement with the casing 9 due to the indirect action of
inner wedge 5 through compression springs 8, where an axial range
of movement remains after this positive engagement is achieved
between the actuating element 5 and the inner wedge 4, or between
the actuating element 5 and the intermediate ring 5a.
[0054] This axial travel essentially results here due to the fact
that the compression springs 8 are not compressed completely when
positive engagement is achieved. An axial travel thus remains that
is provided by the compression of compression springs 8 achieved
during positive engagement up to the maximum possible compression
of compression springs 8, for example when their coils contact each
other or a separate stop is provided. The construction of the grip
head according to the invention is therefore such that due to this
remaining travel the outer sleeve 1 is able to continue moving
axially within this given travel even when there is positive
engagement between the inner wedges 4 and the casing until an
effective engagement is created between jaws 2 of the first
clamping device and the casing 9. This effective engagement can be
provided, for example, by a nonpositive, positive, and/or
frictional engagement between the jaws 2 of the first clamping
device and the casing 9.
[0055] What is thus effected during movement of the sleeve 1, in
particular axially downward relative to the normal working
position, is first a positive engagement to axially secure in place
the casing 9 to the second grab means, and, once this is achieved,
the effective engagement between jaws 2 of the first clamping
device and the casing 9 in response to a further movement by the
sleeve 1, thereby enabling torque to be transmitted.
[0056] When carrying and manipulating the casing 9, this type of
grip head according to the invention thus provides not only the
lifting forces exerted for this purpose but also at the same time
the ability to rotate the casing due to the capability of
transmitting torque, thus reducing adhesion between the casing 9
and the ground, and significantly facilitating the process of
insertion.
[0057] When there is reverse movement by the sleeve 1, i.e. upward
relative to the normal working position, the positive engagement
between the jaws 2 and the casing 9 is thus first released in the
reverse order, where in this case when the casing 9 is suspended
the positive engagement is initially maintained between the inner
wedges 4 of the second clamping device and the drill pipe, since
the casing is supported by its weight on the inner wedges 4 through
its shoulder/step 9a described above, and these elements are thus
loaded, instead of through the sleeve/actuating element, through
the casing axially downward and thus in the direction of gravity,
with the result that the positive engagement is maintained in a
self-locking fashion.
[0058] It is only in the first case mentioned above, when the
casing releases the inner wedges 4, that the grip head drops
relative to the casing, with the result that the positive
engagement between the casing 9 or shoulder 9a and inner wedges 4
is removed, and inner wedges 4 are moved upward axially by the
spring load, thereby releasing the casing.
[0059] Provision is preferably made in the device according to the
invention whereby the second grab means is above the referenced
first grab means relative to a normal working position of the grip
head. It is also possible to reverse this arrangement.
[0060] In FIG. 1, the grip head according to the invention
illustrated here furthermore has a circulation pipe 14 rotationally
fixed to this grip head and extending coaxially of the central axis
M through the grip head, and a cover plate 15 extending across the
upper end of the tube 3 and rotationally fixed thereto.
[0061] The lower end of the circulation pipe 14 here terminates
inside 1 the grip head according to the invention, or below the
lower end of the tube 3, thereby always ensuring that the casing 9
introduced from below into the grip head according to the
invention, which casing coaxially surrounds circulation pipe 14,
engages with its upper end above the lower end of the circulation
pipe 14. Provision is made here whereby the upper end of the casing
9, and in particular a step or shoulder 9a disposed on this upper
end, can be gripped securely by the above-described inner wedges 4,
thereby securing in place the casing axially.
[0062] FIG. 1 here furthermore reveals that a bladder 11 of annular
design is disposed in the annular space between the circulation
pipe 14 and the casing 9, which bladder has a fluid supply line 12
that also extends through the top cover plate 15 and is attached
here to an inner annular part of a rotary feedthrough fitting 13,
this inner annular part being designed to be rotationally fixed to
circulation pipe 14. Inflation of the bladder 11 can thus be
achieved by the fluid supply line to the rotary feedthrough fitting
13, with the result that the annular space between the circulation
pipe 14 and the casing 9 can be sealed against the drilling mud
that is pumped into the casing 9 through the circulation pipe 14.
The pumped-in drilling mud thus can only move downward inside the
casing 9 and cannot move upward past the bladder 11, with the
result that the drilling mud in the casing 9 is only pumped
downward and lubricates the borehole, thereby ensuring easier
insertion of the casing 9 into the borehole. In particular the
inflated bladder ensures that any built-up pressure of the drilling
mud is maintained completely within the casing 9.
[0063] As was mentioned above but not illustrated in the FIGURE,
the rotary feedthrough fitting 13 can have not only one conduit to
conduct fluid but optionally multiple conduits, in particular two
additional conduits, in order to operate cylinder-piston units not
shown here so as to move the outer sleeve 1 axially relative to the
tube 3.
[0064] The constructive design of the grip head according to the
invention as presented here can thus ensure that a casing is
secured in place axially by the second grab means in the grip head
described here and also that a transmission of torque to the casing
can be effected by the first grab means with jaws 2, where at the
same time drilling mud can be applied through the circulation pipe
into the casing and a seal continues to be assured between
circulation pipe and casing.
[0065] It must be stated in regard to all of the embodiments that
the technical features referenced in connection with an embodiment
can be employed or are employed not only in the specific embodiment
but also in the other embodiments. All of the disclosed technical
features of this description of the invention must be classified as
essential to the invention and can be applied either in any
combination with each other or alone. Throughout the entire
disclosure, an implementation of the invention is also understood
by the fact of mentioning that a feature can be provided, or that a
method step can be implemented in which the relevant feature is
provided, or a relevant method step is performed.
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