U.S. patent application number 13/327195 was filed with the patent office on 2012-06-21 for rock bolt.
Invention is credited to Frank Schmidt.
Application Number | 20120155971 13/327195 |
Document ID | / |
Family ID | 45350411 |
Filed Date | 2012-06-21 |
United States Patent
Application |
20120155971 |
Kind Code |
A1 |
Schmidt; Frank |
June 21, 2012 |
Rock Bolt
Abstract
A rock bolt well adapted for use in mining is provided. The rock
bolt includes an anchor tube that encloses an interior space, a
fixing agent arranged inside the interior space for the
substance-to-substance fixation of the anchor tube to stone, a
mobile piston arranged inside the interior space for transporting
the fixing agent out of the anchor tube when the anchor tube is
arranged in a bore hole in the stone, a piston moving mechanism, an
anchor nut, and an anchor plate supported by the anchor nut for
support on the stone.
Inventors: |
Schmidt; Frank; (Munchen,
DE) |
Family ID: |
45350411 |
Appl. No.: |
13/327195 |
Filed: |
December 15, 2011 |
Current U.S.
Class: |
405/259.6 |
Current CPC
Class: |
E21D 20/026 20130101;
E21D 20/023 20130101 |
Class at
Publication: |
405/259.6 |
International
Class: |
E21D 20/00 20060101
E21D020/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 15, 2010 |
DE |
102010063098.5 |
Claims
1. A rock bolt comprising: an anchor tube that encloses an interior
space; a fixing agent initially arranged inside the interior space
of the anchor tube, the fixing agent configured to provide a
substance-to-substance fixation of the anchor tube to stone into
which the anchor tube is inserted, a mobile piston arranged inside
the interior space of the anchor tube, the mobile piston configured
to transport the fixing agent out of the anchor tube; an anchor
nut; an anchor plate supported by the anchor nut, the anchor plate
configured to support the stone into which the rock bolt is
inserted; and a piston moving mechanism configured to move the
mobile piston, the piston moving mechanism comprising a spindle
drive.
2. A rock bolt according to claim 1 wherein the anchor nut and the
anchor plate are fastened at a rod arranged inside the anchor tube,
the rod being fastened via a fastening device at the anchor tube
such that the fastening of the rod at the anchor tube is only
released beginning at a predetermined tensile force in the rod,
whereby the rod can be partially moved outwardly so that the rock
bolt comprises a gliding anchor.
3. A rock bolt according to claim 1, comprising a threaded rod and
a fastening device, the threaded rod comprising an external thread,
the fastening device comprising an annular part with an internal
thread, wherein the annular part is fastened at the anchor tube and
the internal thread of the annular part engages the external thread
of the threaded rod.
4. A rock bolt according to claim 3, wherein the internal thread of
the annular part is located inside of the anchor tube.
5. A rock bolt according to claim 3, wherein the internal thread of
the annular part comprises a specialty thread which destroys the
external thread of the threaded rod beginning at a predetermined
tensile force.
6. A rock bolt according to claim 1, wherein the spindle drive
comprises a threaded rod and an annular part with an internal
thread, the internal thread engaging the threaded rod.
7. A rock bolt according to claim 6, wherein the mobile piston is
fastened directly or indirectly to the threaded rod.
8. A rock bolt according to claim 1, wherein a rear end of the
anchor tube is closed by a cap, and at least one of the anchor tube
and the cap comprises at least one opening to guide the fixing
agent from the interior space enclosed by the anchor tube.
9. A rock bolt according to claim 1, wherein the fixing agent
comprises an adhesive component and a curing component.
10. A rock bolt according to claim 9, wherein the adhesive and
curing components are each arranged in separate bags.
11. A rock bolt according to claim 1, wherein a mixer is arranged
between the fixing agent and at least one opening of the anchor
tube, the mixer configured to mix the fixing agent prior to the
emission of the fixing agent from at least one opening.
12. A rock bolt according to claim 5 wherein the threaded rod
comprises a stop positioned and configured to limit the ability of
the threaded rod to move outwardly.
13. A method for fixing a rock bolt comprising the steps of:
implementing a bore hole into stone; inserting the rock bolt into
the bore hole; transporting a fixing agent from an interior space
enclosed by an anchor tube of the rock bolt through at least one
opening into a space between the anchor tube and the stone by
moving a piston in the interior space towards the fixing agent,
wherein the piston is moved via a spindle drive of the rock bolt;
fastening of the anchor tube to the stone with the fixing agent;
and, allowing the fixing agent to cure.
14. A method according to claim 13, wherein the spindle drive
comprises a threaded rod, and wherein moving the piston comprises
applying a torque upon the threaded rod from the outside such that
the threaded rod is set into a rotary motion about a longitudinal
axis of the threaded rod and the threaded rod is screwed with an
external thread to an internal thread proximate to the anchor tube
so that by the threaded rod an axial motion is performed inwardly
such that the threaded rod is screwed into the interior space
enclosed by the anchor tube.
15. A method according to claim 14, wherein the piston is fastened
at the threaded rod and performs an axial motion directed inwardly
together with the threaded rod.
16. A method according to claim 14, wherein prior to screwing the
threaded rod inwardly into the anchor tube, the threaded rod is
only partially arranged in the interior space enclosed by the
anchor tube, and during the transporting of the fixing agent out of
the interior space enclosed by the anchor tube the threaded rod is
essentially screwed entirely into the interior space enclosed by
the anchor space.
Description
RELATED APPLICATIONS
[0001] The present application claims priority to German Patent
Application DE 10 2010 063 098.5, filed Dec. 15, 2010, and entitled
"Gesteinsanker" ("Rock Bolt"), the entire content of which is
incorporated herein by reference.
FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] [Not Applicable]
[MICROFICHE/COPYRIGHT REFERENCE]
[0003] [Not Applicable]
BACKGROUND OF THE INVENTION
[0004] The present invention relates to a rock bolt, for example,
for mining applications, and a method for fixing a rock bolt in
stone.
[0005] In mining and tunnel construction rock bolts are used in
order to prevent rock movements of adjacent stone, to slow such
movements, or to secure larger split-offs of adjacent rock, and
thus allow a safer operation. Here, two functional principles are
known, which sometimes are combined. In mechanical systems the
fastening of the anchor occurs by friction fitting, with mechanical
stone and/or rock anchors generally also showing an expanding
sleeve. In chemical rock bolts the anchor tubes are connected to a
curing cement or resin as a fixation means in a
substance-to-substance manner to the base and/or the adjacent
stone. The rock bolts are installed here with or without any
prestressing in the adjacent stone. Contrary to tunnel
construction, rock bolts in mining, e.g., underground coal mining,
serve only for a temporary securing of the stone, because generally
the temporarily secured stone will be mined in a later processing
step and thus the rock bolts are removed again from the stone.
[0006] U.S. Pat. No. 4,601,614 shows a rock bolt for tunnel
construction and mining. A two-component fixing agent in two
cartridges is arranged inside an interior space enclosed by an
anchor tube. The external end of the anchor tube comprises an
opening to introduce water under high pressure into the interior
space enclosed by the anchor tube. A piston is arranged articulate
inside the interior space and by moving the piston the
two-component fixing agent is transported and/or pressed through
holes in the anchor tube into a space between the anchor tube and
the stone. For this purpose, an opening is provided at the external
end of the anchor tube, through which water can be introduced under
high pressure into the interior space enclosed by the anchor tube
and by this water the piston is pressurized, so that the piston is
moved inwardly and thus the fixation means is expressed. It is
therefore disadvantageously necessary to require a high pressure
pump to create highly pressurized water to move the piston for a
substance-to-substance fastening of the anchor tube with the fixing
agent.
BRIEF SUMMARY OF THE INVENTION
[0007] An objective of aspects of the present invention therefore
comprises providing a rock bolt and a method for fixing a rock bolt
in stone, in which with little technical expense the fixing agent
can be inserted into the space between the stone and the anchor
tube and/or the rock bolt embodied as a gliding anchor requires
only little space in the tunnel and/or work gallery produced
underground.
[0008] Such an objective may be attained in a chemical rock bolt,
particularly for application in mining, comprising an anchor tube,
which encloses an interior space, a fixing agent arranged inside
the interior space for a substance-to-substance fixation of the
anchor tube at the stone, a mobile piston arranged inside the
interior space to transport the fixing agent out of the anchor tube
when arranging the anchor tube in a bore hole in the stone, at
least one means to move the piston, an anchor nut, and an anchor
plate supported by the anchor nut to be placed upon the stone. The
at least one means may be embodied as a spindle drive for moving
the piston and/or the anchor nut and the anchor plate fastened at a
rod arranged inside the anchor tube. The rod may be fastened at the
anchor tube with a fastening device such that the fastening of the
rod at the anchor tube is only released when a predetermined
tensile force in the rod is exceeded, and thus the rod is partially
mobile towards the outside such that the rock bolt represents a
gliding anchor. The anchor nut and the anchor plate can be embodied
as a single piece or as two separate components.
[0009] In order to move the piston, i.e., to express the fixing
agent out of the interior space into a space between the anchor
tube and the stone, it is therefore no longer required to
expensively provide a high-pressure pump in the tunnel or gallery
in order to move the piston with high-pressurized water. The rock
bolt comprises a spindle drive so that the piston can be moved by a
mere application of a torque at the rock bolt, particularly at the
outside.
[0010] The rock bolt may also be further embodied as a gliding
anchor. The gliding anchor shows a gliding function such that
beginning at a predetermined tensile force compensated by the rock
bolt, i.e., at the pressure acting upon the anchor plate which is
caused by the stone, the rock bolt is extended in its length and
thus a motion is permitted at the stone which reduces the tensile
forces compensated at the rod (below the predetermined tensile
force as a threshold, so that no more gliding occurs) and thus a
better securing of the stone is ensured. Here, after the expression
of the fixing agent from the interior space the rod is essentially
arranged underneath the interior space, i.e., the rod projects only
slightly beyond the exterior end of the anchor tube, so that the
gliding anchor requires only little structural space outside the
stone. In the gliding anchors known from prior art the gliding
function at the anchor nut is implemented such that the anchor nut
glides outwardly at a larger projection of the rod and/or the
anchor tube. Thus, in the gliding anchors known from prior art a
large amount of space is required prior to the gliding of the
gliding anchor for the projection at the anchor tube and/or the rod
for the nut.
[0011] According to aspects of the present invention, if the
tensile force to be compensated by the rod and/or the force at the
rock bolt to be compensated by the rod at the fastening device
falls below a predetermined tensile force the motion of the rod
towards the outside is hindered again, relative to the anchor tube
with the fastening device, so that greater forces can be
compensated by the rock bolt.
[0012] In an additional embodiment, the rod represents a threaded
rod with an external thread and the fastening device is an annular
part with an internal thread, e.g., a nut, and the annular part is
fastened at the anchor tube and the internal thread of the annular
part engages the external thread of the threaded rod.
[0013] In an additional embodiment, the annular part is embodied in
one piece at the anchor tube, particularly by an internal thread
being embodied inside the anchor tube. The annular part can here
represent a separate part fastened to the anchor tube or an annular
part with an internal thread can be embodied in one piece with the
anchor tube, for example, such that an internal thread is provided
at the external end section inside the anchor tube.
[0014] In another variant the internal thread of the annular part
is embodied as a specialty thread, which destroys the external
thread of the threaded rod only beginning at a predetermined
tensile force or vice versa.
[0015] Beneficially, the spindle drive to move the piston may be
formed from the threaded rod and the annular part with the internal
thread.
[0016] In an additional embodiment, the piston is fastened directly
or indirectly at the threaded rod.
[0017] In an additional embodiment, the rear end of the anchor tube
is closed by a cap, and the anchor tube and/or the cap comprise at
least one opening to guide the fixing agent out of the interior
space enclosed by the anchor tube. On the one hand, the cap can be
a separate part, or also be embodied in one piece together with the
anchor tube.
[0018] In a supplementary embodiment, the fixing agent,
particularly resin or cement, comprises two components, e.g., an
adhesive component and a curing component.
[0019] Preferably the two components are each arranged separated in
a bag. Here, any device for storing the two separate components is
considered a bag, for example a cartridge or any other
container.
[0020] In an amended embodiment a mixer is arranged between the
fixing agent and at least one opening to mix the fixing agent,
particularly the two components, before the fixing agent is ejected
through at least one opening.
[0021] Beneficially, the rod may be provided with a stop,
preferably an annular stop, so that the mobility of the rod towards
the outside is limited by said stop. Here, the stop may be a
separate component or be embodied in one piece with the rod,
particularly a threaded rod. Furthermore, the stop may also be
formed by the piston.
[0022] A method according to aspects of the present invention for
fixing a rock bolt in stone, particularly a rock bolt as described
in this application, includes the steps of implementing a bore hole
in the stone, inserting the rock bolt into the bore hole,
transporting a fixing agent from an interior space enclosed by an
anchor tube of the rock bolt through at least one hole into a
space, particularly an annular space between the anchor tube and
the stone, by way of moving a piston in the interior space towards
a fixing agent, a substance-to-substance fastening of the anchor
tube by the fixing agent to the stone, and curing the fixing agent,
with the piston being moved by a spindle drive at the rock bolt,
particularly inside an interior chamber enclosed by the anchor
tube.
[0023] In an additional embodiment the spindle drive comprises a
threaded rod. A torque is applied from the outside to the threaded
rod such that the threaded rod is set into a rotary motion about
the longitudinal axis of the threaded rod, and the threaded rod is
screwed with an external thread to an internal thread at the anchor
tube such that the threaded rod performs an axial motion towards
the inside, i.e., the threaded rod is screwed into the interior
space enclosed by the anchor tube.
[0024] In an additional variant the piston fastened at the threaded
rod performs the inwardly directed axial motion together with the
threaded rod.
[0025] In an additional variant, prior to the threaded rod being
screwed into the interior space enclosed by the anchor tube, the
threaded rod is only partially arranged in the interior space
enclosed by the anchor tube, and during the expression of the
fixing agent from the interior space enclosed by the anchor tube
the threaded rod is essentially entirely screwed into the interior
space enclosed by the anchor tube. Here, "essentially entirely
screwed into the interior space enclosed by the anchor tube" means
that the threaded rod is screwed into the interior space, for
example, by at least about 70%, 80%, 90% or 95%. This way, only a
small part of the threaded rod, i.e., for example, less than about
30%, 20%, 10%, or 5% is arranged outside the interior space so that
after the screwing in and the compression of the space between the
anchor tube and the stone with the fixing agent the rock bolt
requires only little operating space in the tunnel or gallery.
[0026] In an additional embodiment the components of the rock bolt,
for example the anchor tube, the piston, the spindle drive, the
anchor nut, the anchor plate, the rod, the fastening device, the
annular part, the cap, and/or the stop are made at least partially,
preferably entirely, from metal, for example steel or a steel
alloy, or fiberglass-reinforced plastic.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0027] In the following an exemplary embodiment of the invention is
described in greater detail with reference to the attached
drawings.
[0028] FIG. 1 shows a longitudinal cross section of a rock bolt
formed in accordance with an embodiment of the present invention,
which is inserted into a bore hole in stone with a fixing agent not
yet inserted into the space between the stone and the anchor
tube.
[0029] FIG. 2 shows a longitudinal cross section of the rock bolt
according to FIG. 1, in which the fixing agent is inserted into the
space between the stone and the anchor tube.
DETAILED DESCRIPTION OF THE INVENTION
[0030] In accordance with an embodiment of the present invention, a
rock bolt 1 embodied as a gliding anchor 2 may be used in mining
for the temporary securing of stone in galleries. The rock bolt 1
comprises an anchor tube 3, which encloses an interior space 4. The
rock bolt 1 represents a chemical rock bolt 1, i.e., using a fixing
agent 5 arranged in the interior space 4 to the anchor tube 3 to be
fastened in a substance-to-substance fashion to the stone 28. For
this purpose, a bore hole 29 must be implemented in the stone 28
and then the rock bolt 1 must be inserted into the bore hole 29.
This status is shown in FIG. 1, prior to the expression of the
fixing agent 5 into a space between the anchor tube 3 and the stone
28. FIG. 2 shows the rock bolt 1 connected to the stone 28 in a
substance-to-substance manner. In the illustrated embodiment, the
fixing agent 5 represents a resin 6, which includes an adhesive
component 7 and a curing component 8. The adhesive component 7 is
stored in a first bag 9 and the curing component 8 is stored in a
second bag 10. The two bags 9, 10 are stored in the interior space
4.
[0031] Prior to the expression of the fixing agent from the
interior space 4, a rod 16, embodied as a threaded rod 17 in the
illustrated embodiment, is arranged approximately half in the
interior space 4, with the other half outside the interior space 4,
i.e., in an operating space 30 of a hollow space or gallery for
mining. A fastening device 19 is fixed inside at the anchor tube 3
in the exterior end section as an annular part 20 at the anchor
tube 3. The annular part 20, for example, a nut 21 with an internal
thread 22, is, in the illustrated embodiment, for example, welded
to the anchor tube 3. Here the external thread 18 of the threaded
rod 17 engages the internal thread 22 of the annular part 20 so
that this way the threaded rod 17 is indirectly fastened to the
anchor tube 3. A piston 11 is fastened at the interior end of the
threaded rod 17. The interior end of the anchor tube 3 is closed by
a cap 23 with an opening 24. Through the opening 24, the fixing
agent 5 can flow from the interior space 4 of the anchor tube 3
towards the outside into the space, particularly annular space,
between the anchor tube 3 and the stone 28. In the illustrated
embodiment, a mixer 25 is arranged at the opening 24, through
which, due to the geometric arrangement of the mixer 25 in the
interior space 4, the fixing agent 5 must mandatorily flow from the
two bags 9, 10 first through the mixer 25 and then through the
opening 24 to the outside. Here, the mixer 25 comprises, for
example an appropriate geometry, such that the fixing agent 5 flows
meanderingly or tube-like through the mixer 25 and thus a mixing of
the adhesive component 7 with the curing component 8 of the resin 6
occurs prior to flowing out of the opening 24.
[0032] At the exterior outer end of the threaded bolt 17 an anchor
nut 14 is screwed onto the external thread 18 of the threaded rod
17 with an internal thread and an anchor plate 15 is placed on the
anchor nut 14. In the illustrated embodiment, the anchor plate 15
comprises a bore hole without an internal thread, with the threaded
rod 17 being arranged therein. Thus, according to the illustration
in FIG. 2, a pressure can be applied by the stone 28 upon the
anchor plate 15. This pressure is transferred from the anchor plate
15 to the anchor nut 14 and from the anchor nut 14 to the threaded
rod 17 so that a tensile force is applied to the threaded rod 17.
This tensile force is transferred via the annular part 20 to the
anchor tube 3 and from the anchor tube 3 at the outside in a
substance-to-substance manner (by a substance-to-substance contact)
by the fixing agent 5 to the stone 28.
[0033] The piston 11 is moved inwardly in order to insert the
fixing agent 5 into the space between the anchor tube 3 and the
stone 28, i.e., according to the illustration of FIG. 1, upwardly.
This way, the piston 11 destroys the first and second bag 9, 10 so
that the adhesive component 7 and the curing component 8 move, and
due to the reducing volume of the internal space 4 between the
piston 11 and the cap 23, the fixing agent 5 is pressed through the
mixer 25 and the opening 24 into the space between the anchor tube
4 and the stone 28, and subsequently cures. For this purpose, the
rock bolt 1 comprises a spindle drive 13 as a mechanism 12
configured to move the piston 11. Here, the threaded rod 17 and the
annular part 20 with the internal thread 22 serve as the spindle
drive 13. The external end of the threaded rod 17 includes a
respective geometry, for example the shape of a hexagon in the
cross section, so that a torque can be applied upon the threaded
rod 17, for example via a pneumatic screw, and thus the threaded
rod 17 is set into a rotary motion about its longitudinal axis.
This way, the threaded rod 17 is moved inwardly, i.e., according to
the illustration in FIG. 1, towards the top, due to the engagement
of the external thread 18 of the threaded rod 17 with the internal
thread 22 of the annular part 20.
[0034] With the motion of the threaded rod 17 the piston 11 also
performs the motion according to the illustration of FIG. 1
upwards, because the piston 11 is fastened to the threaded rod 17.
In FIG. 2 the fixing agent 5 is already pressed into the space
between the anchor tube 3 and the stone 28, i.e., the anchor tube 3
is fastened to the stone 28 in a substance-to-substance fashion,
particularly by way of gluing. Here, in the installed state shown
in FIG. 2, the threaded rod 17 is essentially completely arranged
inside the interior space 4. Thus, only a small portion of the
threaded rod 17, for example less than about 10% or 5%, is located
outside the interior space 4. This way, in the installed state of
the rock bolt 1 only very little operating space is required in the
operating area 30 in the mining gallery. In the installed state
according to FIG. 2 the anchor plate 15 contacts the stone 28 and
thus can compensate pressures. Further, shear forces perpendicular
in reference to a longitudinal axis of the threaded rod 17 and/or
the anchor tube 3 can also be compensated by the rock bolt 1 and
thus the stone 28 can additionally be secured.
[0035] In the illustrated embodiment, the rock bolt 1 is embodied
as a gliding anchor 2. For this purpose, the internal thread 22 of
the annular part 20 is embodied as a specialty thread, which
beginning at a predetermined tensile force in the threaded rod 17
destroys the external thread 18 of the threaded rod 17, for
example, by way of shearing, so that in this way the threaded rod
17 is moved outwardly, i.e., according to the illustration in FIG.
2, downwards in reference to the anchor tube 3. Here, the anchor
nut 14 as well as the anchor plate 15 move together with the
threaded rod 17 outwardly. This way, movements of the stone 28 can
be compensated by the rock bolt 1 being a gliding anchor 2 without
this leading to the rock bolt 1 breaking. When the tensile force
and/or the pressure to be compensated by the threaded rod 17 upon
the anchor plate 15 falls back below the predetermined threshold
for the tensile force, the external thread 18 of the threaded rod
17 is no longer destroyed by the specialty thread of the internal
thread 22 of the annular part 20, and the threaded rod 17 no longer
moves towards the outside.
[0036] A stop 26 embodied as an annular stop 27 in the upper end
section of the threaded rod 17 provides that during gliding, i.e.
during a motion of the threaded rod 17 towards the outside, the rod
cannot completely move out. By the annular stop 27 contacting the
annular part 20 a gliding of the gliding anchor 2 and/or a motion
of the threaded rod 17 towards the outside is prevented. After the
annular stop 27 has contacted the annular part 20, the gliding
anchor 2 is no longer able to glide and compensates the tensile
forces at the threaded rod 17 until the tensile forces applied
cause the rock bolt 18 to fail, for example the threaded bolt 17
breaking or the adhesive bonding failing between the fixing agent 5
and the stone 28.
[0037] Overall, the rock bolt described above provides valuable
advantages. In order to move the piston 11, i.e. the expression of
the fixing agent 5 from the interior space 4, provision of
expensive high-pressure pumps is no longer required in mining
operations. The piston 11 can be moved by only applying a torque
upon the threaded rod 17 at the outside, for example via a
pneumatic screw. In the installed state according to FIG. 2, the
rock bolt 1 only requires little operating space 30, because the
threaded rod 17 is arranged only slightly outside the anchor tube 3
to accept the anchor nut 4 and the anchor plate 15, and shows no
increased length outside the interior space 4 in the installed
state according to FIG. 2 to compensate gliding motions of the
anchor nut 14 on the threaded rod 17.
* * * * *