Note: Descriptions are shown in the official language in which they were submitted.
CA 02491263 2004-12-29
TITLE OF THE INVENTION
A rock bolt anchor having concurrent chemical and mechanical anchoring means
and method for
using the same.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of my co-pending Canadian patent
application entitled "Dual
Mechanical & Resin Anchor Bolt" filed in the Canadian Intellectual Property
Office on June 30,
2004 and having a serial number of 2,470,212.
REFERENCE TO MICROFICHE APPENDIX
Not applicable.
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to a rock stabilizing apparatus for anchoring unstable
rock formations in
underground mines and construction sites and more particularly relates to an
apparatus and method
that concurrently employs both chemical and mechanical anchor means to anchor
a rock bolt
within an unstable rock formation.
CA 02491263 2004-12-29
Background of the Invention
It is well known in mining and construction operations to reinforce roofs,
sides and floors of
tunnels and shafts using rock bolting. The rock bolts are inserted into a
drilled hole and are
S anchored in place chemically by either a quick curing resin-based adhesive
material or
mechanically by such devices as expanding anchors adapted to frictionally
engage the wall of a
drilled hole. Examples of both methods are found in United States Patents
6,146,055, 6,698,980
5,344,257 and 5,219,248.
Using a concurrent combination of mechanical and chemical anchors to anchor a
rock bolt in a
drilled hole is also known in the art and has the combined advantages
associated with each
individual method. One such device is described in United States Patent
5,222,835 "Resin-Mixing
Article for Mine Roof Anchor" issued to Wright on June 29, 1993. However,
Wright does not
teach an integrated chemical-mechanical anchor, but rather describes a device
where the resin
package is placed in the drilled hole in advance of the rock bolt and then the
rock bolt is inserted to
pierce the package and permit the resin to flow around a portion of the rock
bolt. Mechanical
anchoring means in the form of a conventional expanding anchor assembly is
then used to anchor
the rock bolt. The Wright invention discloses a number of weaknesses in
combined chemical-
mechanical rock bolt anchoring systems. First of all, the Wright invention
does not keep the resin
material within a predefined portion of the annulus between the rock bolt and
the wall of the
drilled hole. The resin is permitted to flow around the rock bolt in an
uncontrolled manner and
back down the drilled hole until such a time as the resin has sufficiently
cured to prevent flow.
This can have the result of creating voids within the resin material and
wasting resin adhesive that
may flow down the drilled hole and merely coat the wall of the drilled hole
rather than anchor the
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CA 02491263 2004-12-29
rock bolt to the wall of the drilled hole. The effect is that the total
adhesive capability of the resin
is not achieved. Secondly, the resin package is inserted into the drilled hole
in advance of the rock
bolt. This means that the resin package could be damaged during insertion and
tamping to the top
of the hole. Resin leakage will again result in the reduction of resin
adhesive capability.
Therefore there is a requirement to provide an apparatus that integrates both
chemical and
mechanical bonding means into rock bolt anchor, takes full advantage of the
total adhesive
capabilities of the adhesive material and protects the resin package from
damage before it needs to
be ruptured. There is also a fizrther need to provide for a mechanical
anchoring means that can be
adapted with an integral chemical anchoring means for use in fragmented rock
formations.
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CA 02491263 2004-12-29
OBJECTS OF THE INVENTION
It is an object of this invention to provide a rock bolt anchor having both
chemical and mechanical
anchoring means that overcomes the disadvantages associated with the prior
art.
It is a further objective of this invention to provide a rock bolt anchor that
has the effect of
controlling the flow of resin adhesive so that the resin adhesive is confined
to a specific area of the
annulus thereby taking full advantage of the binding capabilities of the
resin.
It is yet a further objective of this invention to provide a rock bolt anchor
that combines a
mechanical anchoring system with a chemical anchoring system in a cooperative
fashion.
Still another objective of the invention to provide a rock bolt anchor that is
well suited to
fragmented rock formations.
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CA 02491263 2004-12-29
SUMMARY OF THE INVENTION
My invention seeks to resolve the disadvantages associated with the prior art
and meet the
objectives stated herein by providing a rock bolt anchor that uses a
combination of chemical and
mechanical means to fix a rock bolt into a drilled hole. The rock bolt anchor
is attached to the
threaded end of a rock bolt and inserted snuggly into a drilled hole in a rock
formation forming an
adjacent annulus between the wall of the drilled hole and the rock bolt
anchor. The rock bolt
anchor comprises a top portion and a bottom portion. The top portion contains
the chemical
means for anchoring the rock bolt into the drilled hole. It consists of a
spring loaded resin release
mechanism that is adapted for containing a package of adhesive resin for
injection into the annulus
between a top and bottom bulkhead. The package of resin is pressurized so that
once it is pierced;
the adhesive resin is forced from the package into the annulus between the
bulkheads thereby
fixing the rock bolt within the drilled hole. The bottom portion contains the
mechanical means for
anchoring the rock bolt into the drilled hole. The mechanical means includes a
main body that
supports a pair of outer shells that are forced into a gripping contact with
wall of the drilled hole.
The main body includes a central bore that is threaded with a standard thread
for receiving the
threaded top end of the rock bolt. In another embodiment of my invention, the
threaded bore of
the main body may have multiple threads to increase the speed at which the
rock bolt passes
through the main body and speed up the overall rock bolting process. Under
certain
circumstances, the time taken for a specific rock bolting process may halved
using multiple
threads over standard threads.
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One fixrther advantage offered by my invention is that if the user wishes to
inject a grouting
material into the drilled hole then the main body bottom end has a standard'/4
inch thread that can
be connected to source of grout for that purpose.
The spring loaded release mechanism comprises a first and second bail each
having a circular
center portion and a pair of legs extending downwards. The legs of the first
bail temporarily
connect the top portion of the rock bolt anchor to the bottom portion of the
rock bolt anchor at the
top of the main body. The legs of the second bail are shorter and cooperate
with the legs of the
first bail to form an open chamber for carrying a package of adhesive resin.
The spring loaded
release mechanism has a first retracted position maintained by a wing nut to
permit the resin
package to be inserted into the chamber. The rock bolt anchor is threaded onto
the end of a rock
bolt and a package of resin is inserted into the chamber. Prior to inserting
the rock bolt and anchor
combination into the drilled hole, the wing nut is removed thereby freeing the
spring loaded
release mechanism to act against the package of resin pressurizing it. The
rock bolt and anchor
combination is inserted into the drilled hole. Once the resin package is
punctured, the spring
loaded release mechanism forces the resin out of the package and into the
annulus between the
bulkheads.
The bottom portion of the rock bolt anchor consists of a main body having
opposed upwardly
tapered sections, a pair of outer shells carried on the opposed upwardly
tapered sections of the
main body, a third bail and a hollow ported lance. The outer shells are held
on the main body by a
unique dove-tail joint. The third bail has a circular center portion with a
hole and a pair of legs
that first extend downwards and then taper inwards. The end of each leg is
attached to the top of
one of the outer shells. The third bail also has a pair of anti-rotation tabs
that prevent the anchor
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CA 02491263 2004-12-29
bolt from rotating as the rock bolt is rotated. The hollow ported lance and
the main body are
threaded onto the end of the rock bolt.
To install the combined rock bolt anchor and rock bolt into a drilled hole,
the main body is
threaded onto the end of the rock bolt. The rock bolt threads advance through
the main body so
that two or three threads extend beyond the top surface of the main body. The
hollow ported lance
is then threaded onto the end of the rock bolt. This secures the rock bolt
anchor to the rock bolt.
The wing nut is removed from the spring loaded resin release mechanism to
pressurize the resin
package. The combination rock bolt and rock bolt anchor are inserted into the
drilled hole to a
desired location. Then the rock bolt is rotated. The standard threads on the
main body advances
the rock bolt through the main body so that the lance on the end of the rock
bolt moves through the
hole in the third bail and into piercing contact with the resin package. Then
the spring loaded resin
release mechanism operates to force the resin through the hollow lance out of
the ports and into
the annulus between the bulkheads. The rock bolt continues to advance with
three dynamic
results. Firstly, the top portion of the rock bolt anchor separates from the
bottom portion of the
rock bolt anchor. Secondly, the rotating advancing rock bolt threads through
the main body and
acts on the third bail forcing it upwards. Thirdly, the main body is forced
down the threaded rock
bolt. The second and third results cause the outer shells carried on the main
body and the main
body itself to move in opposite directions. Hence, the shells move along the
tapers of the main
body and are forced outwards into a gripping contact with the wall of the
drilled hole thereby
forming the rock bolt mechanical anchor.
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CA 02491263 2004-12-29
The combined chemical and mechanical anchor of my invention results in three-
times the holding
strength of a conventional anchor. My invention is well suited to applications
such as anchoring
fragmented rock and coarse grained material such as concrete.
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BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be more readily understood by reference to the following
description, taken
with the accompanying drawings, in which:
Figure 1 illustrates one embodiment of my invention in partial cross-section.
Figure 2 comprises two illustrations of the frst bail of one embodiment of my
invention.
Figure 3 comprises two illustrations of the second bail of one embodiment of
my invention.
Figure 4 comprises a view of spring loaded resin release mechanism of my
invention.
Figure 5 is the same embodiment of my invention as Figure 1 but turned 90
degrees about its
longitudinal axis.
Figure 6 is a cross-section side view of one embodiment of my invention
illustrating additional
detail of the bottom portion.
Figure 7 is a view of the main body of my invention.
Figure 8 is a view of the same main body of Figure 7 but turned 90 degrees on
its longitudinal
axis.
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Figure 9 comprises illustrations of one of the outer shells of one embodiment
of my invention.
Figure 10 is an illustration showing the outer shells fixed to the main body
of my invention using a
unique dove tail joint.
Figure 11 is an illustration of the third bail of my invention.
Figure 12 is an illustration of the lance of my invention.
Figure 13 is an illustration of the top bulkhead of one embodiment of my
invention.
Figure 14 is an illustration of the bottom bulkhead of one embodiment of my
invention.
Figure 15 is an illustration of my invention inserted into a drilled hole in a
rock formation prior to
rotation of the rock bolt.
Figure 16 is an illustration of my invention in a drilled hole after the rock
bolt has been rotated.
Figure 17 comprises various illustrations of components of my invention
showing dimensions.
Figure 18 comprises various illustrations of components of my invention
showing dimensions.
CA 02491263 2004-12-29
DETAILED DESCRIPTION
Referring now to Figure l, there is illustrated a preferred embodiment my
invention as it would
appear prior to insertion into a drilled hole. My invention ( 10) is a rock
bolt anchor having a
combination of chemical means for fixing the rock bolt inside of a drilled
hole and mechanical
means for fixing the rock bolt inside of a drilled hole. The chemical means is
a package of
adhesive resin (12) shown in ghost lines. The mechanical means is a pair of
opposed outer shells
(14) carned by a main body (I6). A major advantage and innovative feature of
my invention is the
combined chemical and mechanical means for anchoring the rock bolt which
results in a three fold
increase in anchoring strength over conventional anchoring means. The
operation of both the
chemical means and mechanical means will be more fully explained below.
Still referring to Figure 1, for purpose of this description, the rock bolt
and rock bolt anchor will
always be considered to be oriented up (top of the page) and down (bottom of
the page) as if
inserted vertically into the roof of a mine. Hence the rock bolt anchor will
have a top end (18) and
a bottom end (20). My invention has a top portion (22) and a bottom portion
(24). The top and
bottom portions appear to overlap in Figure 1 because the legs of the first
bail of the top portion
are used to connect the top portion to the bottom portion as more fully
explained below.
General Components and Construction of the Top Portion
The top portion (22) comprises the following components: a first bail (26), a
second bail (28) co-
axial with the first bail and a spring loaded resin release mechanism
generally shown as (30) and
will be described in greater detail below. In Figure 1, the spring loaded
resin release mechanism is
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CA 02491263 2004-12-29
shown in a pre-insertion and retracted state which permits the insertion of
the resin package ( 12)
into the open chamber (32).
Referring now to Figure 2 there is shown in illustration A the first bail (26)
as it would appear
when stamped from appropriate stock material using a cutting form. A person
skilled in the art of
manufacture would know that stamping these metal parts one of the more cost-
effective ways to
manufacture them in bulk and so the further description of how each part of
the rock bolt anchor is
manufactured is not required here. A person skilled in the art would also know
that, unless
otherwise stated herein, the first bail and all other parts of my invention
would be made from a
suitable steel alloy material with a thickness and strength sufficient to
withstand the forces to be
the exerted during the rock bolting process. In illustration B the first bail
(26) is shown in its
formed configuration for installation in the rock bolt anchor top portion.
Illustration A and B are
not drawn to the same scale. The first bail comprises a flat circular middle
portion (40) placed
across the longitudinal axis (8) of the rock bolt anchor. The flat circular
middle portion (40) has
an upper surface (42), a bottom surface (44), a diameter (46), and a first
bail aperture (48) centered
on the longitudinal rock bolt anchor axis (8). There is a first pair of
opposed legs comprising a
first leg (50) having a lower engagement portion (52), a length (54), a bottom
tip (56), an inside
surface (58) and an outside surface (60).
Referring back to Figure 1, the first leg (50) extends vertically downwards
from the flat circular
middle portion and the first leg lower engagement portion (52) is adapted for
placement within
notch (62) in the main body (16) for fixing permanently the rock bolt anchor
top portion (22) to
the rock anchor bolt bottom portion (24) by spot welding.
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CA 02491263 2004-12-29
Referring back to Figure 2, there is also an opposite second leg (70) having a
lower engagement
portion (72), a Iength equal to first leg length (54), a bottom tip (74), an
outside surface (76) and
an inside side surface (78).
Referring back to Figure 1, the second leg extends vertically downwards from
the flat circular
middle portion and the second leg lower engagement portion (72) is also
adapted for placement
within notch (80) by spot welding to permanently fix the top portion of the
anchor to the bottom
portion.
Referring now to Figure 3 there is shown in illustration A the second bail
(28) as it would appear
when stamped using a cutting form. Illustration B shows the second bail (28)
in its formed
configuration for installation in the rock bolt anchor top portion. The second
bail comprises a flat
circular middle portion (92) placed across the longitudinal axis (8) of the
rock bolt anchor. The
flat circular middle portion (92) has an upper surface (94), a lower surface
(96), a diameter (98)
that is substantially equal to diameter (46), and a second bail aperture (
100) centered on the
longitudinal rock bolt anchor axis (8). There is a second pair of opposed legs
comprising a first
leg ( 102) having a length ( 104) that is substantially shorter than length
(54), a bottom tip ( 106), an
inside surface (108) and an outside surface (110). The first Ieg extends
vertically downwards from
the flat circular middle portion. There is a second leg ( 116) identical to
the first leg ( 102) having
an inside surface ( 118), a tip ( 120) and an outside surface ( 122). The
second bail top portion
includes notch ( 112) and notch ( 114) which are adapted to receive the inside
surfaces ( 108) and
( 118) of the first pair of opposed legs ( 102) and ( 116).
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CA 02491263 2005-06-07
Replacement Sheet
Referring back to Figure 1, second bail (28) is oriented below first bail (26)
so that the first and
second pairs of opposed legs are oriented at a right angle to each other. This
orientation forms the
four sided open chamber (32) in which the resin package ( 12) is placed
protectively against
premature rupture. The purpose of the notches ( 112) and ( 114) will become
apparent with the
description of the spring loaded resin release mechanism (30).
Referring; now to Figure 4, there is shown the components comprising the
spring loaded resin
release mechanism generally shown as (30). The spring loaded resin release
mechanism
comprises second bail (28) (Illustration A) having aperture (100) notches
(112) and (114) and legs
(102) and (116) and first bail (26) not shown here so that the mechanism can
be viewed. Referring
back to figure 1, the relationship between the first and second bails is
clear. The spring loaded
resin release mechanism includes a top-hat shaped member (130) shown in
partial cross-section in
Illustration B. T'he member (130) includes a lower circular flange (132) and
an upper cylindrical
portion ( 134). Fixed to the top centre of the cylindrical portion is the
first end of a threaded stem
(136) having a free end adapted to receive a wing nut (138). The threaded stem
receives the
second b~3il aperture ( 100) and the first bail aperture (48). The top hat-
shaped member sits within
the four sided open chamber. Illustration C views the bottom of member ( 130)
showing bottom
(140) of flange (132) the inside (142) of the cylindrical portion (134) and
four notches (143),
(144), (146), and (148). The four notches are adapted to receive in a sliding
relationship the inside
surfaces of the first and second pair of opposed legs so that the circular
flange is guided up and
down within the open chamber by the first and second pairs of opposed legs.
Referring; back to Figure l, member (130) is shown in cross-section and spring
(150) is shown
disposed around member ( 130) cylindrical portion ( 134). The top surface of
the spring abuts
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CA 02491263 2004-12-29
against the bottom surface of the second bail flat circular middle portion and
the bottom of the
spring abuts against the top surface of the lower circular flange. Figure 1
also illustrates that
notches (143) and (146) slidingly engage the inside surfaces of second bail
legs (102) and (116)
and notches (144) and (148) slidingly engage the inside surfaces of first bail
legs (50) and (70). It
is clear that the legs of the first and second bails act as guides for member
(130). In Figure 1, wing
nut (138) is threaded onto stem (136) and spring (150) is compressed so that
the member (130) is
in its first retracted position. This permits the placement of resin package (
12) within the chamber
(32). Obviously, once the wing nut is removed and the spring released, the
bottom surface of
member (130) will compress the resin package (12) thereby pressurizing its
contents. Once the
resin package is pierced as more fully explained below, member (130) will
travel down the guide
legs and force all of the resin out of the package. Figure 1 illustrates the
spring loaded resin
release mechanism in its first operating state with the spring compressed and
the flange retracted.
Figure 15 shows the mechanism in its second operating state with the wing nut
removed and the
spring released to compress the package of resin prior to insertion into the
drilled hole. Figure 16
shows the mechanism in its third operating state wherein the resin package has
been pierced and
the spring fully extended in the open chamber.
General Components and Construction of the Bottom Portion
Refer now to Figure 5 and Figure 6. Figure 5 is identical to Figure 1 except
that the resin package
is removed. Figure 5 and Figure 6 again illustrate the relationship between
the top portion of the
rock bolt anchor and its bottom portion. As well, Figure 6 shows more fully
the spring (150) and
shows the bottom portion in cross-section. Figure 5 and Figure 6 illustrate
the same embodiment
of the invention except that the illustration in Figure 6 is rotated 90
degrees around axis (8).
CA 02491263 2004-12-29
Starting from the top (200) of the bottom portion (24) and working towards the
bottom (20) of the
bottom portion the various components of the bottom portion are identified.
There is top bulkhead
(202) for sealing the top of the annulus between the anchor and the drilled
hole wall when the
anchor and rock bolt combination is inserted into the drilled hole. There is a
third bail (204)
having a pair of legs (206) and (208) that each have a first vertical portion
(210) and a second
inclined portion (212). There is main body ( 16) having a bore (214) having an
upper threaded
portion having standard threads in the preferred embodiment to pass the
threaded end of the rock
bolt (220) as it is rotated. In alternate embodiments of my invention the
threads may be multiple
threads. There is the pair of opposed outer shells ( 14) comprising a first
shell (222) and a second
shell (224). Note that third bail (204) legs (206) and (208) are fixed to the
top of each shell (222)
and (224) respectively. The pair of opposed shells are carried on the main
body in a unique dove
tail joint (226). The bottom portion of the main body carnes the bottom
bulkhead (228) which
seals the bottom of the annulus when the anchor is inserted into the drilled
hole. The bottom
portion also includes lance (232) for piercing the package of resin. One
advantage of my
invention is that the bottom portion has an inside surface (230) which is
threaded with a'/4 inch
thread to permit attachment to a grouting source for grouting operations as
necessary. Fixed to the
top of the rock bolt (220) is lance (232) which is hollow and ported (234).
Below the lance (232)
is baffle member (236).
The Main Body
Referring now to Figure 7 and Figure 8 the main body ( 16) will be described
in more detail. In
Figure 7 Illustration A is a side view of main body ( 16) and Illustration B
is a top view of main
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body (16). The top portion (250) of main body (16) is a carted body comprising
a flat circular top
surface (252) and a pair of opposed tapers (254) and (256) commencing at the
top surface (252)
and depending a predetermined distance to the top surface (260) of the bottom
portion (262) of the
main body. The taper terminates in a dove tail which angles the top surface
(260) outwards and
upwards at a predetermined angle (264). The bottom portion (262) of the main
body below the
dove tail includes a groove (266) adapted to carry the lower bulkhead and
incorporates a 3/4 inch
pipe thread (264) for grouting purposes. The dove tail design creates an
interlocking ability with
the pair of outer shells to hold the outer shells on the main body.
Referring to Figures 1, 7 and 8, the bottom engagement portions (52) and (72)
of the first pair of
opposed legs (50) and (70) are adapted to be permanently fixed in notches (62)
and (80) on the
main body by spot welding.
Referring to Figures 6, 7 and 8, rock bolt (220) is threaded into the main
body (16) by way of
internal threads (216) which are standard threads in the preferred embodiment
to pass the rock bolt
through the main body.
The Outer Shells
Referring to Figure 9 there is shown front (Illustration A) side (Illustration
B) and bottom views
(Illustrations C and D) of one of the pair of opposed outer shells (222) and
(224). The shells are
semi-circular in cross-section as shown in Illustrations C and D. The inside
surface (270) is
curved and adapted to sit astride rock bolt (220) across a length delineated
by the inverse "V"
(274) shown in Illustration A. Each of the outer shells has a plurality of
evenly spaced serrations
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(276) which are adapted for engagement with the wall of the drilled hole. The
shells have a
bottom surface which is flat in elevation view and inclined upwards in profile
view (278) having a
second predetermined angle equal to the fast predetermined angle (264) of the
surface (260) of the
main body (16). In this way, the outer shells are held in position in a dove
tail joint as illustrated
in Figure 10 Illustration B which shows outer shells (222) and (224) carried
on main body ( 16) and
held in position by the dove tail joint (280) which is a novel and inventive
feature of my invention.
Figure 10 Illustration A shows the flat top surface of the main body. The
shells also include
notches (271) and (273) on their respective top inside surfaces. These notches
are adapted to
receive the engagement ends of the third pair of opposed legs of the third
bail as explained below
and illustrated in Figure 6.
The Third Bail
Refer now to Figure 11 there is shown the third bail (200) of my invention.
Illustration A shows
the third bail having been stamped from suitable sheet metal stock. Figure 11,
illustration B shows
the third bail in its formed shape as shown in Figure 6. Figure 11,
illustration C is a top view of
the formed third bail and Figure 11 illustration D is a bottom view of baffle
member (236). Third
bail (204) comprises a flat circular middle portion (300) placed across the
axis of the rock bolt
anchor (8). Middle portion (300) has an upper surface (302), a lower surface
(304), a diameter
(306), and a third bail aperture (308) centered on the rock bolt anchor axis
(8). The third bail
aperture (308) is further shaped into aperture (309) formed having flared rim
(310) with convex
wall (312) surrounding the aperture and creating a concave circular flange
(314) around the
outside of the aperture. Middle portion (300) has first notch (320) and a
second opposed notch
(322) adapted for receiving the first pair of opposed legs (50) and (70)
respectively of the first bail
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(26). The third bail includes a third pair of opposed legs (206) and (208)
each of which have a
bottom engagement portion (330) and (332) for engaging and fixation to notches
(271) and (273)
of the outer shells in a permanent manner by spot welding. Each leg on the
third bail has a first
vertical portion (210) and an inclined portion (212). The inclined portion
fits over the main body
tapers as shown in Figure 6. .
Still referring to Figure 11, illustration A, the third bail includes a pair
of anti-rotation tabs (240)
and (242) which extend outwards from the top surface (302) of the middle
portion (300) and then
depend downwards to engage the wall of the drilled hole in a frictional fit so
the anchor does not
rotate when the bolt is rotated. This is shown Illustration B at item (240).
The tabs are displaced
45 degrees counter-clockwise from each leg of the third pair of legs.
Referring to Figure 11 Illustration C, there is shown a top view of third bail
(204) as it would
appear installed in the lower portion of the rock bolt anchor. Notches (320)
and (322) are adapted
to engage the inside surfaces (58) and (78) of the legs (50) and (70) of the
first bail of the top
portion.
Figure 11, Illustration D shows the baffle member (236) fixed permanently by
spot welding
between the legs of the third bail. The baffle has a top surface (324) and a
bottom surface (326)
and an opening (328) for passing the rock bolt (220). The baffle (236) is
placed on top of the main
body (16) as illustrated in Figure 6. Notches (340) and (342) engage the
inside surfaces of third
bail legs (206) and (208) and notches (344) and (346) engage the inside
surfaces of first bail legs
(50) and (70).
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The Lance
Refer now to Figure 12 there is shown two illustrations A and B of the lance
(232). Figure A
shows the lance in cross-section. The lance has a set of threads (362) adapted
to receive the
threaded end of the rock bolt. As previously described, when the lance is
threaded on the end of
the rock bolt it has the effect of fixing the entire anchor to the rock bolt.
The lance is a hollow
cylindrical member having a lumen (364) extending from its sharp free end tip
(366) to its
opposite end (368). The lance is ported (234) in four locations around its
circumference to permit
resin to flow from the lumen through the ports and into the annulus. The lance
base (371) is
knurled (372) around its bottom circumference to assist in finger tightening
of the lance onto the
end of the rock bolt. The base includes a threaded bore that is in
communications with lumen. In
operation and as more fully explained below, as the rock bolt is rotated and
advances through the
main body, the lance will rise to engage and pierce the pressurized resin
package. The spring
loaded resin release mechanism previously described forces the resin out into
the lumen of the
lance, through the ports and between the top and bottom bulkheads thereby
forming a strong
chemical anchor. The top surface (380) of the base of the lance will abut
against the bottom
surface (304) of the third bail forcing it upwards with the two outer shells.
As well the main body
will be forced downwards by the rotating rock bolt engaging the standard
threads of the bore in the
main body. The effect is to force the shells out against the wall of the
drilled hole thereby
mechanically anchoring the rock bolt.
CA 02491263 2004-12-29
The Top and Bottom Bulkheads
Refer now to Figures 13 and 14. A novel feature of my invention is the use of
top and bottom
bulkheads to seal a portion of the annulus so that the resin is forced into a
defined area and is not
allowed to flow beyond that area. This concentrates the resin in a specific
location and affords a
much stronger chemical bond instead of letting the resin flow freely in the
drilled hole annulus as
done in the prior art. Referring now to Figure 13, Illustration A shows the
top bulkhead (202) in
elevation view and illustration B shows the top bulkhead in cross-sectional
view through line C-C.
The top bulkhead comprises a first tapered ring member (380) comprising an
outside tip (382) in
sealing contact with the wall of the drilled hole. An aperture (384) is
surrounded by a convex rirn
(386) having an inside surface (388), a top end (390) and a bottom end (392).
The inside surface
(388) of the convex rim (386) is adapted to fit within the concave circular
flange (314) of the third
bail (204). The top bulkhead further has a flat bottom surface (394) that
rests upon the top surface
(302) of the third bail. There is an inclined upper surface (396) extending
from said top end (390)
IS of the convex wall (386) to the tip (382). In operation, the top bulkhead
is a flexible material such
as resilient rubber with sufficient elastic strength to seal the upper end of
the annulus and is
installed on the flange as shown in Figure 6.
Referring to Figure 14, Illustration A shows the bottom bulkhead (228) in plan
view and
Illustration B shows the bottom bulkhead in cross-sectional view through line
C-C. The bottom
bulkhead comprises a second tapered ring member (400) comprising an outside
tip (402) in sealing
contact with the wall of the drilled hole. An aperture (404) is surrounded by
a convex rim (406)
having an inside surface (408), a top end (410) and a bottom end (412). The
inside surface (408)
of the convex rim is adapted to fit within the circumferential groove (266) of
the main body ( 16).
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CA 02491263 2004-12-29
The bottom bulkhead further includes a flat bottom surface (414) extending
from the bottom end
(412) of the convex wall and extending to the tip (402) of the ring member
(400) and an inclined
upper surface (416) extending from the top end (410) of the convex wall to the
tip of the tapered
ring member. The second tapered ring is made from the same material as the
first tapered ring and
operates in a similar fashion.
Another advantage to my invention is that the rock bolt anchor can be secured
to the rock bolt as
one single unit comprising the top portion and the bottom portion with the two
outer shells. The
anchor is easily threaded onto the end of the rock bolt and secured using the
lance.
The Operation of My Invention
Referring to Figure 15, there is shown a preferred embodiment of my invention
placed in a drilled
hole (500) having a wall (502). Note how the top bulkhead (202) and the bottom
bulkhead (228)
seal a portion (504) of the annulus (506) between the rock bolt anchor and the
wall of the drilled
hole. The package of resin (12) is shown in the open chamber. Since the wing
nut (138) has been
removed the spring (150) is free to exert compressive forces on the resin
package (12) thereby
pressuring the contents. The resin package bulges on its side to show
pressurized contents. When
the rock bolt (220) is rotated the lance (232) rises to a piercing engagement
with the resin package.
Resin is forced through the lumen in the lance and out of the ports and into
the area of the annulus
(504) between the top and bottom bulkheads. This keeps the resin confined to a
defined space and
increases the chemical bond of the rock bolt to the wall of the drilled hole.
The annulus portion
(504) will fill completely with resin encapsulating the rock bolt anchor
between the bulkheads.
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CA 02491263 2004-12-29
Referring now to Figure 16, there is shown my invention in a drilled hole
(500) having a wall
(502). The top bulkhead (202) and the bottom bulkhead (228) are shown in
sealing contact with
the wall (502) of the drilled hole. The area (504) between the top and bottom
bulkheads is filled
with resin from the depleted resin package (12) which has been compressed and
emptied by the
spring loaded resin release mechanism (30). Note that lance (232) has plunged
deeply into the
resin package. The rock bolt (220) threads (221) have rotated a distance (520)
above the baffle
member (236) until the top surface (380) of the lance base (371) abuts against
the underside (304)
of third bail (204). Once the rotating rock bolt advances to this point it
advances no further and
continued rotation of the rock bolt within the double threaded main body
causes the main body to
travel downwards. This, in turn, separates the shells (222) and (224) from the
main body (16) and
causes them to ride up the tapered portion of the main body ( 16) and outwards
so that the serrated
edges are in firm contact with the wall of the drilled hole creating a
mechanical bond with between
the rock bolt and the wall of the drilled hole.
Referring now to Figures 17 and 18, there is shown various components of my
invention
previously described illustrating dimensions of one embodiment of my
invention.
Understandably, these dimensions may change to manufacture my rock bolt anchor
to suit the
needs of the rock bolting operation.
Method of Use
My invention as described herein can be employed in rock bolting operations by
following these
steps:
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CA 02491263 2004-12-29
a. selecting a rock bolt having a threaded end;
b. selecting a rock bolt anchor having a top portion and a bottom portion;
c. threading said rock bolt threaded end into said rock bolt anchor bottom
portion
main body so that at least three threads of the threaded end of the rock bolt
protrude
above said main body;
d. selecting a lance;
e. threading said lance onto said threads protruding above the main body
thereby
fixing the rock bolt anchor to the rock bolt;
f. loading a package of adhesive resin into said top portion;
g. removing said wing nut thereby releasing said spring loaded resin release
mechanism to come into compressive contact with said package of adhesive resin
thereby pressurizing the contents thereof;
h. inserting the rock bolt anchor and rock bolt into the drilled hole so that
the rock bolt
anchor is placed in a desired location within the drilled hole;
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CA 02491263 2004-12-29
i. sealing said desired location within the drilled hole between the top
bulkhead and
the bottom bulkhead;
j. rotating the rock bolt in a clockwise direction so that the lance rises
into piercing
contact with the package of adhesive resin causing the spring loaded resin
release
mechanism to squeeze the contents of the resin package into the lumen within
the
lance and out of the ports within the lance into the desired location within
the
drilled hole between the top and bottom bulkheads so that the entire bottom
portion
of the rock bolt is encased in resin thereby chemically anchoring the rock
bolt in the
drilled hole; and,
k, continuing the rotation of the rock bolt so that the third bail and the
outer shells
attached to the third bail are driven upwards and further so that the main.
body is
driven downwards thereby causing the outer shells to move up the tapers of the
main body and into firm contact with the wall of the drilled hole thereby
mechanically anchoring the rock bolt into the drilled hole.
Although the description above contains many specifications, these should not
be construed as
limiting the scope of the invention but as merely providing illustrations of
some of the presently
preferred embodiments of this invention. Thus the scope of the invention
should be determined by
the appended claims and their legal equivalents rather than by the examples
given.
