Note: Descriptions are shown in the official language in which they were submitted.
12~19~0
CLAUDE C. WHITE and FREDERICK CARR
MINE ROOF ANCHOR ASSEMBLY
BACKGROUND OF THE INVENTION
This invention relates to the securing of anchor
bolts in drilled openings in a mine roof for supporting the
roof.
Mine roof bolts of the expansion shell type have
been widely used for supporting mine roofs. In more recent
years, resin anchors have been employed. In the resin type
anchor, a resin and catalyst cartridge is inserted into
the back of a mine roof opening, following which an anchor
bolt is forced upwardly into the opening, thereby rupturing
the cartridge to permit the resin and catalyst to gravitate
downwardly between the bolt and the wall of the opening.
Upon mixing of the catalyst and resin, the resin sets to secure
the bolt in the mine roof. In the use of resin type anchors,
difficulty has been experienced in properly mixing the resin
and catalyst to product the greatest securing effect, and
preventing either undermixing or overmixing of the resin
and catalyst.
Resin has also been employed to reinforce or bond
expansion shells in mine roofs as illustrated in United States
Patent No. 3,702,060 to James D. Cummings issued ~ovember 7,
1972, United States Patent No. 4,160,614 to Stanley J. Baldwin
issued July 10, 1979 and United States Patent No. 4,162,133
to Carl A. Clark et al issued July 24, 1979. United States
12SlS~O
Patent Nos. 4,160,614 and 4,162,133 mix the resin and catalyst by
rotating the bolt in one direction, and actuate the expansion shell by
rotation of the bolt in the opposite direction. Additionally, United
States Patent No. 3,188,815 to Fritz Schuermann issued June 15, 1965
discloses an anchor bolt assembly wherein a resin and catalyst cartridge
is punctured by the tip of the roof bolt, following which the bolt is
rotated a predeteremined number of times for the purpose of mixing the
resin and catalyst, an expansion shell carried by an intermediate portion
of the bolt then being urged to its expanded position to grip the mine roof.
Ithas been found, however, that with all of the above combination
anchors, there is great difficulty in securing a proper mixture of the
resin and catalyst, with consequent reduction in the effectiveness of the
resin in securing the assembly in the mine roof opening. Also, where a
sequence of separate and distinct operations are required to mix the resin
and catalyst and then to activate the expansion shell, installation time
is necessarily increased along with the danger of improper installation.
SUMMARY OF THE INVENTION
The present invention is a mine roof anchor assembly for co-
operation with a dual compartment resin and catalyst cartridge inserted
into a mine roof opening, the anchor assembly including and elongate bolt
having a head at one end and being threaded for a portion of its length at
its otller end; a rebar engaged witll the threaded end of the elongate bolt,
the rebar being arranged to rupture the resin and catalyst cartridge when
the assembly is forced upwardly into a mine roof opening, thereby permitting
the resin and catalyst to gravitate downwardly between the wall of the
opening and the rebar; an expansion shell carried by said elongate bolt
subjacent said rebar, the expansion shell including a plurality of wedge
segments having wall-engaging ribs extending outwardly from their outer
surfaces, the inner wall of the wedge segments being tapered inwardly from
top to bottom; a bail member having spaced legs, the lower ends of which
are connected to diametrically opposite portions of the upper extremities
of the wedge segments and including a connecting portion joining the
upper ends of said legs, the connecting portion comprising a disk having a
12S~O
central opening through which the elongate bolt passes, a cone nut
threadedly engaged with the elongate bolt between the legs of said bail
member and in predetermined spaced relation to the wedge segments the
outer surface of said cone nut being tapered inwardly from top to bottom
for engagement with the tapered inner wall of the wedge segments to cause
expansion of the wedge segments into gripping engagement with the mine
roof opening, and means for limiting longitudinal movement of the expansion
shell and bail member with respect to the elongate bolt whereby, upon
rotation of the elongated bolt and rebar, the cone nut is moved longitudinally
of the bolt into expanding engagement with the wedge segments, the number
of revolutions of the elongate bolt required to move the cone nut to cause
expansion of the shell corresponding to the number of revolutions of the
rebar required to effect proper mixing of the resin and catalyst.
DESCRIPTION OF THE FIGURES OF THE DRAWINGS
FIG. 1 is a sectional view taken through a mine roof opening
showing the initial stage of insertion of one form of the mine roof
anchor assembly of the present invention.
1?5:~9~iO
--4--
FIG. 2 is a ~iew similar to FIG. 1, showing the
second stage of installation of the mine roof anchor
assembly of FIG. l;
FIG. 3 is a view similar to FIGS. l and 2, showing
S ~he third stage in the installation of the mine roof
anchor assembly;
FIG. 4 is a sectlonal. view taken along the line
4--4 of FIG. 3 looking in the direction of the arrows;
FIG. 5 is a fragmentary elevational view of a
modified form of the mine roof anchor assembly, showing
the assembly in the initial position of installation;
FIG. 6 is a sectional view taken along the line
6--6 of FIG. 5, looking in the direction of the arrows;
FIG. 7 is a longitudinal sectional view of the
mine roof anchor assembly of FIG. 6;
FIG. 8 is a view similar to FIG. 6, showing the
mine roof anchor assembly fully installed;
FIG. 9 is a fragmentary elevational view of a
third form of the mine roof anchor assembly of the present
invention, showing the assembly in its initial position;
FIG. 10 is a sectional view taken along the line
10--10 of FIG. 9 looking in the direction of the arrows;
FIG. 11 is a fragmentary longitudinal sectional
view of the mine roof assembly of FIG. 9, and
FIG. 12 is a fragmentary elevational view of the
mine roof anchor assembly of FIG. 9, showing the assembly
in installed position, portions thereof being shown in
section.
DESCRIPTION OF FORM OF INVENTION ILLUSTRATED
.
IN FIGS. 1 TO 4
.
In FIGS. 1 to 3 there is illustrated a mine roof 20
having an elongated opening 22 therein, in the back end of
which is inserted a conventional dual compartment cartridge
24 containing resin and a catalyst. In accordance wïth
the present invention, the ~ine roof anchor assembly is
inserted into the elongated opening for the purpose of
providing a combination resin and expansion shell securement
~S:1960
--5--
of the assembly with the mine roof.
The present assembly includes an elongated bolt 26
having a head 28 at one end thereof which en~a~es a
support plate 30 which is interposed between the head and
the mine roof as illustrated in FIGS. 2 and 3. At a
point intermediate its length, bolt 26 is threaded at 32
to the opposite end thereof, which end is threadedly en-
gaged with rebar 34 which comprises a cylindrical body
having double helical ribs 36 extending along the outer
periphery thereof. The rebar is preferably of a size to
provide an interference fit in elongated opening 22,
rebar of 1-1/8 inch diameter in a 1-3/8 inch diameter hole
having been found to operate efficiently in carrying out
the objects of the present invention.
The mine roof anchor assembly further includes an
expansion shell generally designated 38 which is mounted
on bolt 26 subjacent rebar 34.
Expansion shell 38 includes a lower collar or ring
40 which surrounds bolt 26 and a plurality of like, wedge
segments 42 which are connected to collar 40 by reduced
neck portions 44. Wedge segments 42 are slightly spaced
apart and are of arcuate conformation in cross section.
The outer surface of each wedge segment is pro~ided with
a series of transverse ribs 46 adapted for gripping en-
gagement with the mine roof wall when the expansion shellis actuated. As shown to advantage in FIG. 1, the inner
surface of each wedge segment is inwardly tapered from
top to bottom as shown as 48.
Expansion shell 38 further includes a cone or wedge
nut 50 having an axial threaded bore 52 for threaded en-
gagement with threaded portion 32 of bolt 26. The outer
surface of cone nut 50 is tapered inwardly from a point
near the top to its bottom thereof, as indicated at 54,
for sliding engagement with the tapered wall 48 of
wedge segments 42. It will be noted from FIGS. 1 and 2
that in its initial position when inserted into the
elongated opening 22, cone nut 50 lies partially within
the upper end of expansion shell 38, but is not in ex-
panding engagement therewith.
~2~19~0
--6--
It is sa~ient feature o~ the present invention
to provide nut means, preferably comprising a palnut
56 which is threadedly engaged with threaded portion 32
of bolt 26 in supporting engagement with expansion shell
38, to hold the latter in the position shown in FIGS. 1
and 2.
It will be further noted from a consideration of
FIGS. 1 and 2 that palnut 56 is threadedly engaged with
threaded bolt portion 32 at a point which is a predetermined
distance from the unthreaded portion of the bolt. The
number of revolutions of the bolt required to move palnut
56 downwardly to the unthreaded portion of the bolt
corresponds to the number of revolutions required by
rebar 34 to effect proper mixing of the resin and catalyst
after the resin cartridge has been ruptured. At that time,
continued rotat~on o~ bolt 26 causes cone nut 50 to mo~e
longitudinally~the expansion shell, thereby causing en-
gagement of tapering wall surface 54 of the cone nut with
the tapering inner wall surfaces 48 of wedge segments 42
to force the latte~ outwardly into engagement with the
mine roof, as shown to advantage in FIG. 3.
In installation of the mine roof anchor assembly
of FIGS. 1 to 4, dual compartment cartridge~is first in-
serted into elongated opening 22, after which the anchor
assembly is thrust upwardly into the opening, thereby
rupturing the cartridge and permitting the resin and
catalyst to gravitate downwardly between the wall of the
open.ng and the outer periphery of ~ebar 34, the opening
being approximately 1/8 to 1/4 inch wide. The assembly
is rotated mechanically to cause a mixing of the resin
and catalyst indicated at 58. During rotation of bolt
26 and rebar 34, the frictional engagement of expansion
shell 38 with that portion of the roof 20 defining
opening 22, prevents rotation thereof. Also, by virtue
of the frictional engagement of the upper surface of
palnut 56 with the lower surface of expansion shell'38,
palnut 56 also will not rotate but, upon rotation of
bolt 26, palnut 56 and expansion shell 38 supported thereby
move downwardly along the bolt until palnut 56 reaches
lZS1960
--7--
the unthreaded portion of bolt 26.
At this time, rebar 34 has rotated the predetermined
number of revolutions required to effect proper mixing
of the resin and catalyst for obtaining maximum secure-
5 ment of the resin to the rebar and the mine roof. Con-
tinued rotation causes cone nu 50 to pass between the
wedge segments 42 of expansion shell 38, to e~fect out-
ward movement of the segments until ribs 46 thereof
securely engage the mine roof to provide a combination
resin secured and mechanically secured engagement of the
anchor assembly with the mine roof which extends through
a substantial portion thereof.
DESCRIPTION OF FORM OF INVENTI017 ILLUSTRATED
_
IN FIGS. 5 TO 8
In FIGS. 5 to 8, there is illustrated a modified
form of the combination expansion shell and resin secured
anchor assembly of the present invention wherein portions
thereof which are similar to the form of inver.tion illus-
trated in FIGS. 1 to 4, are designated by like, primed
numbers. In this form of the invention, the expansion
shell is designated 60, and includes a lower collar or ring
62 which surrounds threaded portion 32' of bolt 26', and
a plurality of like, wedge segments 64 which are connected
to collar 62 by reduced neck portions 66. The wedge seg-
ments are slightly spaced apart, and the outer surface
thereof is provided with a series of transverse ribs 67
for gripping engagement with the mine roof wall when the
expansion shell is actuated. As shown in FIGS. 7 and 8,
the inner surface of each wedge segment 64 is inwardly
tapered from top to bottom as shown at 68.
Expansion shell 60 further includes a cone nut 70
having an axial thr~aded bore 72 for threaded engagement
with threaded portion 32' of bolt 26'. The outer surface
of cone nut 70 is tapered inwardly from a point near the
top to its bottom thereof, as indicated at 74, for sliding
engagement with the tapered walls 68 of wedge segments 64.
Diametrically opposite side edges of cone nut 70 are cut
away to provide longitudinal grooves 76 and 78, as shown
l ZS 19 6 0
--8--
to advantage in FIG. 6.
In accordance with this orm of the invention,
there is also provided an inverted U-shape bail member
80 which extends upwardly from wedge segments 64. Bail
member 80 is preferably made of relatively rigid material
of uniform width and thickness and includes a pair of
like, spaced legs 82 and 84, the upper ends of which
lie within grooves 76 and 78 of cone nut 70 to insure
proper engagement with the latter. The upper end of
legs 82 and 84 are joined by a connecting portion which
comprises a disk 86 having a central opcninr, 88 through
which threaded portion 32' of bolt 26~ passes for en-
gagement with rebar 34'.
At a point intermediate their lcngth, legs 82 and
84 of bail member 80 are slightly bent inwardly as in-
dicated at 90 and 92. The lower limits of legs 82 and 84
are welded, or secured in any other sui~ble manner to
diametrically opposed portions of wedge scgments 64 as
indicated at 94 and 96.
Expansion shell 60 is held in sul~jacent relation
to rebar 34' by a palnut 56' which, in this form of the
invention is located at the lowermost eY.trcmity of threaded
portion 32' of bolt 26' in order to prcvcnt longitudinal
movement of the palnut and expansion shel' upon rotation
of bolt 26'.
It will be noted from a consideration of ~IGS. 4 and
5 that, in this form of the invention, cone nut 70 lies in
predetermined spaced relation from wedgc scgments 64 so
that, as bolt 26' is rotated, cone nut 70 is threaded
downwardly along threaded part 32' until it moves into
expanding engagement with tapering walls 68 of wedgesegments 64.
The number of revolutions of bolt 26' required
to move cone nut 70 from its initial position shown in
FIG. 4 to the position where it is in expanding engage-
ment with wedge segments 64, as shown in ~IG. 8, corres-
ponds to the number of revolutions of rc~ar 34' to effect
proper mixing of the resin and catalyst 58'.
lZS~ V
The procedure for installing the anchor assembly
illustrated in FIGS. 5 to 8 is substantially the same as
in the installation of the anchor assembly of FIGS. l to
4. It is noted, however, that as cone nut 70 moves longi-
tudinally downwardly on threaded portion 32' of the bolt,it passes through a restricted passageway formed by bent
portions 90 and 92 o legs 82 and 84. This produces a
slight ~lcxing of the bent portions, with resultant
slight expansion o the wedge segments, thereby urging the
segments into frictional engagement with the opening wall
to prevent rotation of the expansion assembly, without
urgin~ the se~ments into gripping engagement with the
wall.
The distance between the cone nut and the shell
enables bail member 80 to be made with relatively long
legs, thcreby permitting the use of thicker, more rigid,
strap matcrial for making the bail member, while at the
same time, permitting the necessary spring action of
the legs which will not resist the expanding action of
the wed~e se~ments. It has been found that a steel strap
of approximately Stl6 inches in width and 3/32 inches to
5/32 inches in thickness obtains the desired results. A
thickness of l/8 inch has been found to produce the best
results.
D~SCRIPTION OF FORM OF INVENTION ILLUSTRATED
_
IN FIGS. 9 TO 12
In FIGS. 9 to 12, there is illustrated a further
modification of the anchor assembly of the present inven-
tion whcrein portions thereof are similar to those des-
cribed in connection with the form of invention illustrated
in FIGS. l to 4. Accordingly, similar parts are identified
by like, double primed numbers.
In accordance with this form of the invention, there
is provided an expansion shell 98 which includes a lower
collar or ring lOO which surrounds threaded bolt part 32',
1~51960
-10-
and a plurality of like, wedge segments 102 which are
connected to collar 100 by reduced neck portions 104.
Wedge segments 102 are slightly spaced apart and are of
arcuate conformation in cross section. The outer surface
of each wedge segment is provided with a series of trans-
verse ribs 106 adapted for gripping engagement with the
mine roof wall when the expansion shell is actuated.
As shown to advantage in FIG. ll, the inner surface of
each wedge segment 102 is inwardly tapered from top to
bottom as shown at 108.
Expansion shell 98 further includes a cone or wedge
nut 110 having an axial threaded bore 112 for threaded
engagemen~ with threaded bolt 26". The ou~cr surface of
cone nut 110 is tapered inwardly from a point near the
top to its bottom thereof, as indicated at 114, for sliding
engagement with the tapered walls 108 of wedge segments 102.
Diametrically opposite edges of cone nut 110 are cut away
to provide longitudinal grooves 114 and 116, as shown to
advantage in FIG. 10.
In accordance with this form of the invention, there
is providcd an inverted U-shape bail member 118 which ex-
tends upwardly from wedge segments 102. Bail member 118
is preferably made of relatively rigid material of uniform
width and thickness and includes a pair of like, spaced
legs 120, 122, the upper ends of which lie within grooves
114 and 116 of cone nut 110 to insure ?roper engagement
with the latter. The upper ends of legs 120 and 122 are
joined by a connecting portion comprising a disk 124 which
overlies the cone nut. Disk 124 is provided with a cen-
tral opening 126 in order to permit the passage of threaded
part 32" of the bolt therethrough for engagement with
rebar 34". Just as in the form of invention illustrated
in FIGS. 5 to 8, at a point intermediate their length,
legs 120 and 122 are bent inwardly at 128 and 130 in order
to provide a restricted passageway through which cone
nut 110 is adapted to pass. The lower limits of legs 120
and 122 are welded or secured in any other suitable manner
to diametrically opposed portions of wedge segments 102,
as indicated at 132 and 134. In this form of the inven-
tion, threads 32" are distorted a~ 136 between the upper
lzs~ o
extremity of bail member 118 and cone nut llO. A specialretainin~ nut 138 is threadedly enga~ed with thrcaded
part 32" of the bolt between disk 124 and distorted threads
136, the outer ?erip;~ery of which nut is serrated as in-
dicatcd at 140 for facility in threading the nut on theend of thc bolt.
The distorted threads 36 prevent nut 138 from
screwing further down threaded part 32" and supports bail
member 118 to prevent the bail member and thc expansion
shell connected thereto from moving longitudinally of the
bolt upon rotation of the latter.
The procedure in installing the assembly in this
form of the invention is substantially the same as in
connection with the form of invention illustrated in FIGS.
5 to 8.
As the bolt and rebar are rotated, the ribs 106
of the expansion shell engage the mine roof wall to pre-
vcnt rotation of the expansion shell and the bail member,
thereby causing cone nut 110 to be threaded downwardly
on threaded part 32" of the bolt into expanding engagement
with the wedge segments of the expansion shell. During
this timc, the distorted threads 136 cause the special nut
to remain stationary. The passage of cone nut 110 through
the restricted passageway formed by bent portions 128 and
~5 130 causes a slight flexing of these portions and a
resultant slight expansion of the wedge segments towards
the latter into frictional engagement with the mine roof
wall to positively preclude any rotation of the expansion
shell.
As also set out above in connection with the form
of invention illustrated in FIGS. 5 to 8, the distance
between the cone nut and the wedge segments require a
predetermined number of revolutions for the cone nut to
effect expansion of the wedge segments into gripping en-
gagemcnt with the mine roof and the number of these revo-
lutions corresponds to the number of revolutions required
to effect proper mixing of the resin and catalyst gravi-
tating through the opening between rebar 34" and the mine
roof.
1 ~ 5 1~ ~ 0
-12-
In all forms of the present invention, installation
is carried out in one continuous operation so that, when
sufficient torque developes due to tension in the bolt,
the drill rotating the bolt stalls and indicates secure
engagemen~ of the shell with the mine roof.
Simultaneously, the bolt and rebar have been ro-
tated a sufficient number of revolutions to effect proper
mixture of the resin and catalyst, without undermixing
or ovcrmixing the resin and catalyst, approximately 20
revolutions havin~ been found to produce optimum results.
The anchor assembly of the present invention affords simple
and economic means for combining the gripping forces of
an expansion shell anchor and a resin anchor in a single
assembly which securely and firmly holds a mine roof bolt
in a roof opening, thereby positively minimizing the
chanccs of failure of the anchor assembly after installa-
tion.
The present assembly furthermore may be readily
instalied in the mine roof opening in one continous opera-
tion by inserting the assembly in the opening and then
rotating the bolt in one direction only. During this
opera~ion, the resin and catalyst are automatically mixed
to the proper degree, following which the expansion shell
is sequentialiy activated into gripping engagement with
the mine roof.
Although there has been herein shown and described
the presently preferred forms of this invention, it is
to be understood that various changes may be made therein
within the scope of the appended claims.
