U.S. patent application number 14/610148 was filed with the patent office on 2015-07-16 for expandable bolt with shielded tip.
The applicant listed for this patent is FCI Holdings Delaware, Inc.. Invention is credited to Arthur J. Craven, Daniel Leon Seegmiller.
Application Number | 20150198042 14/610148 |
Document ID | / |
Family ID | 45064587 |
Filed Date | 2015-07-16 |
United States Patent
Application |
20150198042 |
Kind Code |
A1 |
Craven; Arthur J. ; et
al. |
July 16, 2015 |
Expandable Bolt with Shielded Tip
Abstract
The present invention includes a rock bolt having a
longitudinally expandable tube. The tube includes a longitudinally
extending depression that defines a temporary enclosed longitudinal
passageway. The rock bolt further includes a shielded distal end to
prevent debris from entering the temporary enclosed longitudinal
passageway. The distal end is shielded using a cover which may be a
plug or a cap and may provide a rounded tip for the rock bolt. The
plug may be spherical. The cap may be attached such that its
proximal end abuts the distal end of the rock bolt, is inserted
into the distal end of the rock bolt, or extends beyond the distal
end and along the sidewall of the rock bolt. The present invention
also includes a method of making such a rock bolt and a method of
using such a rock bolt.
Inventors: |
Craven; Arthur J.; (Grand
Junction, CO) ; Seegmiller; Daniel Leon; (Sandy,
UT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FCI Holdings Delaware, Inc. |
Wilmington |
DE |
US |
|
|
Family ID: |
45064587 |
Appl. No.: |
14/610148 |
Filed: |
January 30, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13118678 |
May 31, 2011 |
|
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14610148 |
|
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61351328 |
Jun 4, 2010 |
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Current U.S.
Class: |
405/259.3 ;
29/511 |
Current CPC
Class: |
E21D 20/00 20130101;
E21D 21/004 20130101; Y10T 29/49918 20150115; E21D 21/0026
20130101; E21D 21/0073 20160101; E21D 21/0033 20130101 |
International
Class: |
E21D 21/00 20060101
E21D021/00; E21D 20/00 20060101 E21D020/00 |
Claims
1. A rock bolt comprising: an expandable tube that is partially
collapsed upon itself so as to form a longitudinally extending
depression between two longitudinally extending interior
passageways, wherein the longitudinally extending depression forms
a temporary main passageway at a distal end of the expandable tube,
wherein the two longitudinally extending interior passageways form
the interior of the tube upon expansion, wherein the temporary main
passageway is open at the distal end of the expandable tube,
wherein the two longitudinally extending interior passageways are
closed at the distal end of the expandable tube, and wherein a
pressurized fluid may be delivered into the two interior
passageways to force the depression outward to thereby expand the
expandable tube and compress the expandable tube against
surrounding rock; an end fitting attached to the distal end of the
expandable tube, the end fitting having a sidewall and two open
ends, a first of the open ends extending longitudinally beyond the
closed distal ends of the interior passageways; and a cover
covering the first open end of the end fitting.
2. The rock bold according to claim 1, wherein the cover provides a
rounded tip for the rock bolt.
3. The rock bolt according to claim 1, wherein the cover is a
plug.
4. The rock bolt according to claim 1, wherein the cover is a
cap.
5. The rock bolt according to claim 4, wherein the proximal end of
the cap abuts the distal end of the rock bolt.
6. The rock bolt according to claim 4, wherein the cap comprises a
closed distal end, an open proximal end, and a sidewall extending
from the distal end to the open proximal end that creates an inner
cavity, and wherein the cap is placed over the distal end of the
rock bolt such that the distal end of the rock bolt extends into
the inner cavity of the cap.
7. The rock bolt according to claim 4, wherein the cap comprises a
closed, distal end, an open proximal end, and a sidewall extending
from the distal end to the open proximal end that creates an inner
cavity, and wherein the cap is placed into the distal end of the
rock bolt such that the proximal end of the cap extends into the
temporary longitudinal passageway of the rock bolt.
8. The rock bolt according to claim 1, wherein a central portion of
the cover extends longitudinally from the first open end of the end
fitting a greater distance than a peripheral portion of the cover
extends longitudinally from the first open end of the end fitting
to facilitate centering the rock bolt within a borehole.
9. A method of manufacturing a rock bolt comprising: partially
collapsing a tube upon itself so as to form a longitudinally
extending depression between two longitudinally extending interior
passageways, wherein the longitudinally extending depression forms
a temporary main passageway at a distal end of the expandable tube;
attaching an end fitting to the distal end of the expandable tube,
the end fitting having a sidewall and two open ends, a first of the
open ends extending longitudinally beyond the closed distal ends of
the interior passageways; closing the two longitudinally extending
interior passageways at the distal end of the expandable tube; and
covering the first open end of the end fitting by affixing a cover
to the end fitting.
10. The method according to claim 9, wherein the cover provides a
rounded tip for the rock bolt.
11. The method according to claim 9, wherein the cover is a
plug.
12. The method according to claim 9, wherein the cover is a
cap.
13. The method according to claim 9, further comprising placing a
stiffening tube on a proximal end of the expandable member, wherein
the stiffening tube surrounds the proximal end of the expandable
member and has an opening that aligns with a corresponding opening
in the expandable tube, thereby providing fluid communication to an
interior of the expandable tube.
14. The method according to claim 9, wherein a central portion of
the cover extends longitudinally from the distal end of the first
open end of the end fitting a greater distance than a peripheral
portion of the cover extends longitudinally from the first open end
of the end fitting to facilitate centering the rock bolt within a
borehole.
15. A method of using a rock bolt comprising: providing a rock bolt
comprising: an expandable tube that is partially collapsed upon
itself so as to form a longitudinally extending depression between
two longitudinally extending interior passageways, wherein the
longitudinally extending depression forms a temporary main
passageway at a distal end of the expandable tube, wherein the two
longitudinally extending interior passageways form the interior of
the tube upon expansion, wherein the temporary main passageway is
open at the distal end of the expandable tube, and wherein the two
longitudinally extending interior passageways are closed at the
distal end of the expandable tube; an end fitting attached to the
distal end of the expandable tube, the end fitting having a
sidewall and two open ends, a first of the open ends extending
longitudinally beyond the closed distal ends of the interior
passageways; and a cover covering the first open end of the end
fitting; drilling a borehole in rock; placing the rock bolt in the
borehole; expanding the tube by providing pressurized fluid to the
two interior passageways of the expandable tube, thereby providing
frictional engagement between an exterior of the tube and an
interior of the borehole; and draining the fluid from the interior
of the tube.
16. The method according to claim 15, wherein the cover provides a
rounded tip for the rock bolt.
17. The method according to claim 15, wherein the cover is a
plug.
18. The method according to claim 15, wherein the cover is a
cap.
19. The method according to claim 15, wherein a central portion of
the cover extends longitudinally from the distal end of the first
open end of the end fitting a greater distance than a peripheral
portion of the cover extends longitudinally from the first open end
of the end fitting to facilitate centering the rock bolt within a
borehole.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S.
application Ser. No. 13/118,678, filed May 31, 2011, entitled
"Expandable Bolt with Shielded Tip", and claims-priority from U.S.
Provisional Patent Application No. 61/351,328, filed Jun. 4, 2010,
entitled "Expandable Bolt with Shielded Tip", all of which are
herein incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to a rock bolt having an expandable
tube and a shielded distal end, a method of making such a rock
bolt, and a method of using such a rock bolt.
[0004] 2. Description of Related Art
[0005] Rock bolts are used in underground mines, such as coal
mines, to support the roof and ribs. Installation of conventional
rock bolts involves drilling a borehole into the rock to a desired
depth using an elongated drilling tool (termed the drill steel),
removing the drill steel from the borehole, optionally inserting
adhesive resin cartridges, and retaining the cartridges in the
blind end of the borehole while a bolt, optionally bearing an
expansion anchor, is installed into the borehole. The free end of
the bolt extending out of the borehole is received by a chuck of a
bolting machine. The bolting machine rotates the bolt within the
borehole to mix the adhesive resin and/or expand the expansion
anchor.
[0006] Other rock bolts comprise a longitudinally expandable tube
that includes a longitudinally extending depression between two
curved outer portions where the tube is partially collapsed on
itself. The ends of the tube are folded over to create two enclosed
cavities in the curved outer portions of the tube while a temporary
passageway defined by the depression remains open on the ends.
After placing the rock bolt in the pre-drilled borehole,
pressurized fluid is delivered into the two cavities to force the
depression outward, expand the tube, and compress it against the
surrounding rock. Until the expansion has been completed, the ends
of the passageway defined by the depression are open so that debris
from the borehole can fall into the passageway defined by the
depression.
SUMMARY OF THE INVENTION
[0007] The present invention includes a rock bolt having a
longitudinally expandable tube. The tube includes a longitudinally
extending depression that defines a temporary, enclosed
longitudinal passageway. The rock bolt further includes a cover on
the distal end of the rock bolt to prevent debris from entering the
temporary, enclosed longitudinal passageway, ease insertion of the
rock bolt into the borehole, and assist in alignment of the rock
bolt in the borehole. The cover may be a plug or a cap and may
provide a rounded tip for the rock bolt. The plug may be spherical.
The cap may be attached such that its proximal end abuts the distal
end of the rock bolt, is inserted into the distal end of the rock
bolt, or extends beyond the distal end and along the sidewall of
the rock bolt.
[0008] The present invention also includes a method of
manufacturing a rock bolt, including providing an expandable member
including an expandable tube and an end fitting where the
expandable tube has a longitudinally extending depression disposed
between a pair of outer portions of the tube, the exterior of the
tube defines a temporary, enclosed longitudinal passageway having
an open distal end, and the outer portions of the tube have closed
distal ends; and enclosing the expandable member with a cover such
that a distal open end of the temporary, enclosed longitudinal
passageway of the expandable tube is covered. The cover may be a
plug or a cap and may provide a rounded tip for the rock bolt. The
method may also include placing a stiffening tube on a proximal end
of the expandable tube such that the stiffening tube surrounds the
proximal end of the expandable tube and has an opening that aligns
with a corresponding opening in the expandable tube, thereby
providing fluid communication to an interior of the expandable
tube.
[0009] A method of using a rock bolt, including providing a rock
bolt having an expandable member including an expandable tube
having a temporary, enclosed longitudinal passageway with an open
distal end; and a cover at a distal end of the rock bolt covering
the temporary longitudinal passageway; drilling a borehole in rock;
placing the rock bolt in the borehole; expanding the tube by
providing pressurized fluid to the interior of the tube, thereby
providing frictional engagement between an exterior of the tube and
an interior of the borehole; and draining the fluid from the
interior of the tube. The cover may be a plug or a cap and may
provide a rounded tip for the rock bolt.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a side view of a rock bolt produced according to
the present invention;
[0011] FIG. 2 is a cross-section taken along lines 1-1 of FIG.
1;
[0012] FIG. 3 is a cross-section taken along lines 2-2 of FIG. 1,
as installed in rock strata;
[0013] FIG. 4 is a longitudinal cross-section of the distal end of
a rock bolt according to one embodiment of the present
invention;
[0014] FIG. 5 is a longitudinal cross-section of the distal end of
a rock bolt according to a second embodiment of the present
invention;
[0015] FIG. 6 is a longitudinal cross-section of the distal end of
a rock bolt according to a third embodiment of the present
invention; and
[0016] FIG. 7 is a longitudinal cross-section of the distal end of
a rock bolt according, to a fourth embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0017] Referring now to the drawing figures in which like reference
numbers refer to like elements, FIG. 1 shows a rock bolt 2 which
includes an expandable tube 4 having an initial cross-sectional
profile as shown in FIG. 2. The tube 4 is partially collapsed upon
itself (such as by rolling or drawing) so as to provide a depressed
region 6 between two curved outer portions 8, 10 extending
longitudinally along the tube 4. The tube 4 is produced from a
steel alloy or the like having sufficient strength to function in
rock support, even after deformation from internal hydraulic
pressure as described below. A first stiffening tube 14, having a
sidewall and two open ends, is attached to and surrounds a proximal
end 15 of the tube 4. A lip 18 may extend from stiffening tube 14
for engaging with a rock surface when the rock bolt 2 is inserted
in the borehole.
[0018] A second stiffening tube 20, having a sidewall and two open
ends, is attached to and surrounds a distal end 21 of tube 4
leaving the end of the tube 4 uncovered. A cover 22 covers the
opening in a distal end 23 of second stiffening tube 20, the tube
4, or both and may be fixed thereto by welding or the like. The
outer curved portions 8, 10 of tube 4 abut one another to define a
temporary main passageway 26 as well as interior passageways 28,
30. Main passageway 26 is open at the distal end 21 of tube 4 while
interior passageways 28, 30 are closed as shown in FIGS. 4-7. As
shown in FIG. 1, the first stiffening tube 14 defines an opening 34
which is aligned with an opening (not shown) in tube 4, such that
the openings are in fluid communication with interior passageways
28, 30.
[0019] In operation, a borehole is drilled into the rock to the
desired depth and the bolt 2 is inserted through a bearing plate
and into the borehole. A source of pressurized fluid, such as
water, is delivered through the opening 34 of the first stiffening
tube 14 and an opening in tube 4 into interior passageways 28, 30.
When passageways 28, 30 are filled, the further addition of fluid
creates sufficient hydraulic pressure to force open the tube 4,
such that passageways 28, 30 are conjoined as an interior 35 of the
tube 4 expanding the tube 4, and ultimately compressing the tube 4
against the surrounding rock of the borehole. See FIG. 3. As a
result, main passageway 26 no longer exists. When the tube 4 is
fully expanded and no further fluid is received therein, the fluid
supply is removed and the fluid is drained. In this manner, the
expanded tube 4 frictionally anchors into and/or against the
surrounding rock R.
[0020] The cover 22 may take the form of a plug or a cap. In one
embodiment, the cover 22 is a plug 122 or a plug 222, as shown in
FIGS. 4 and 5, respectively. The plug 122, 222 is placed in the
opening in the distal end 23 of tube 20 such that a first portion
124, 224 thereof is exposed and a second portion 125, 225 is in the
interior of the tube 20. The plug 122, 222 may take any suitable
shape (such as rounded) as long as the main passageway 26 is
covered. The plug 122, 222 may be made of steel or any other
suitable material. The plug 122, 222 may be fixed to the rock bolt
102, 202 by welding or the like. For example, tack welds 32, spaced
apart around the circumference of the plug 122, 222 may be used to
attach the plug 122, 222 to tube 20.
[0021] In one embodiment, such as for rock bolt 102, shown in FIG.
4, plug 122 is spherical. Plug 122 may be placed such that the
exposed portion 124 is one hemisphere of spherical plug 122 and the
second portion 125 inside the opening in the distal end 23 of
second stiffening tube 20 is the other hemisphere as shown.
Alternatively, the plug 122 may be placed such that less of plug
122 is exposed or more of plug 122 is exposed as long as the main
passageway 26 is covered. Plug 122 may take the form of a polished
or unpolished ball bearing.
[0022] In another embodiment, rock bolt 202, shown in FIG. 5, the
exposed portion 224 of the plug 222 may be dome shaped and the
second portion 225 extending into tube 20 may be cylindrical. The
second cylindrical portion 225 may further have a beveled edge 227
as shown.
[0023] Alternatively, the cover 22 may be a cap 322 or a cap 422,
as shown in FIGS. 6 and 7, respectively. Cap 322, 422 may take any
suitable shape (such as rounded) as long as the main passageway 26
is covered. The cap 322, 422 may be made of steel or any other
suitable material. Cap 322, 422 may be fixed to the rock bolt 302,
402 by welding or the like. For example, tack welds 32 spaced apart
around the circumference of the proximal end 329, 429 of cap 322,
422 may be used to attach cap 322, 422 to respective tube 20.
[0024] In one embodiment, such as for rock bolt 302, shown in FIG.
6, cap 322 is hemispherical, and the open proximal end 329 of cap
322 abuts distal end 23 of tube 20. Cap 322 is shown to be hollow
but it could also be solid (not shown), for example, a sphere, such
as plug 122 in FIG. 4, cut in half.
[0025] In another embodiment, such as for rock bolt 402, shown in
FIG. 7, cap 422 has a closed distal end 434, an open proximal end
429, and a sidewall 436 extending from the closed distal end 434 to
the open proximal end 429 creating an inner cavity 438. Cap 422 is
placed over tube 20 such that tube 20 and the distal end 21 of tube
4 are received in the inner cavity 438. The sidewall 436 of cap 422
extends along the sidewall of tube 20. Cap 422 can be fabricated
using any suitable means including, but not limited to, stamping,
molding, or attaching a cover portion to a cylindrical tube. The
distal end 434 of cap 422 may be hollow (as shown) or may be solid
(not shown) as described above for cap 322 of rock bolt 302.
[0026] In another embodiment (not shown), cap 422 could be sized
such that its sidewall 436 fits inside the distal end 23 of tube 20
such that distal end 434 of cap 422 extends beyond distal end 23 of
tube 20. A portion of sidewall 436 may extend beyond the distal end
23 of tube 20 or the length of the sidewall 436 may be adjusted so
that only distal end 434 extends beyond distal end 23 of tube
20.
[0027] The rock bolt can be made by providing an expandable member
which includes an expandable tube 4 and an end fitting (stiffening
tube 20) on the distal end 21 of the expandable tube 4. The
expandable tube 4 has a longitudinally extending depression 6
disposed between a pair of curved outer portions of the tube 8, 10.
The exterior of the tube defines a temporary, enclosed longitudinal
passageway 26 having an open distal end 23 and the outer portions
of the tube 4 define internal passageways 28, 30 which have closed
distal ends 23. The distal end of the tube 4 is then enclosed with
a cover so as to cover the distal open end 23 of the temporary,
enclosed longitudinal passageway 26. The cover may be in the form
of a plug 122, 222 or a cap 322, 422 and may be rounded. The cover
may be secured to the expandable member by welding or any other
suitable method. The method may also include placing a stiffening
tube 20 on a proximal end 15 of the expandable member such that the
stiffening tube 20 surrounds the proximal end 15 of the expandable
member and has an opening 34 that aligns with a corresponding
opening in the expandable tube 4, thereby providing fluid
communication to an interior of the expandable tube 4. The
stiffening tube 20 may be attached to the expandable member by
welding, crimping or any other suitable method.
[0028] The cover keeps debris from entering the main passageway of
the rock bolt when the rock bolt is in the unexpanded condition. It
also allows the rock bolt to be more easily inserted and centered
in the borehole. The domed end of the rock bolt created by the
cover eliminates the sharp angles at the distal end of the rock
bolt which can tend to get caught on the sides of the borehole. The
domed end also allows the rock bolt to be centered more easily in
the borehole.
[0029] The cover also has the advantage of reduced manufacturing
costs compared to other methods of rounding the end, for example,
building up weld metal on top of a blank to round the end. The
cover may be held in place with a minimal number of tack welds as
described above simplifying fabrication and reducing costs. In
addition, manufacturing becomes even easier when producing a rock
bolt according to embodiment 102, shown in FIG. 4. The spherical
plug 122 may be placed in tube 20 in any orientation simplifying
assembly and, thus reducing assembly time.
[0030] The foregoing description sets forth the preferred
embodiments of the invention at the present time. Various
modifications, additions, and alternative designs will, of course,
become apparent to those skilled in the art in light of the
foregoing teachings without departing from the scope of the
invention. The scope of the invention is indicated by the following
claims rather than by the foregoing description. All changes and
variations that fall within the meaning and range of equivalency of
the claims are to be embraced within their scope. Specifically,
while embodiments herein have been described as having a rounded
cover, covers having any shape that covers the main passageway of
the rock bolt are considered within the scope of the invention.
* * * * *