Note: Descriptions are shown in the official language in which they were submitted.
200~06
TITLE
IMPROVED ROCK ANCHOR AND METHOD OF MANUFACTURE
FIELD OF THE INVENTION
The present lnventlon relates to an lmproved rock
anchor and a method of and an apparatus for manufacture thereof.
Rock anchors are steel tendons lnserted down bore holes ln a
scree. A portlon of the tendon ls grouted, and a plate attached
to the tendon. The tendon ls then stressed; the plate bears
upon the scree and thereby stablllses the scree.
Tendons typlcally comprlse a plurallty of steel
strands wound together to form the tendon. To adequately secure
such tendons ln cement, prlor art methods have used machlnes to
unravel the strands. Such machines have required people to
initiate such unravelling prior to insertion into the machine.
This is time consuming and hence expensive. The purpose of
unravelllng the strands ls to lncrease the surface area of the
tendon ln contact wlth the cement to more securely embed the
tendon in the cement. The present lnventlon provides an
alternative form of tendon and a method and an apparatus for
manufacture thereof.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention
there ls provlded a rock anchor comprislng a tendon composed of
a plurallty of strands, the tendon havlng at least two spaced
bulbous portions, wherein between ad~acent bulbous portions
there are a plurality of outer strands hellcally wound around a
centre strand, and in each bulbous portlon the outer strands and
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2002~06
the centre strand are spaced from one another substantlally
around the perlphery of the bulbous portlon.
In accordance wlth another aspect of the present
lnventlon there ls provlded an apparatus for manufacturlng a
rock anchor, comprlslng a tendon having a plurallty of strands
and at least one bulbous portlon ln whlch all the strands are
spaced from one another substantlally around the perlphery of
the bulbous portion, the apparatus comprlslng a palr of spaced
clamp means, each arranged to clamp releasably the tendon
thereln at posltlons spaced apart along the length thereof and
belng mounted ln the apparatus for there to be relative
longltudlnal dlsplaceablllty between the clamp means, and clamp
dlsplacement means for dlsplaclng the clamp means towards one
another ln order to form a sald bulbous portlon ln the tendon
between the two clamp means.
In accordance wlth yet another aspect of the present
lnventlon there ls provlded a method for manufacturlng a rock
anchor comprlslng a tendon havlng a plurallty of stands and at
least one bulbous portlon ln whlch all the strands are spaced
from one another substantially around the perlphery of the
bulbous portion, wherein a tendon ls clamped ln two or more
spaced clamp means whlch are moveable relative to one another,
the clamp means are displaced towards one another to form at
least one sald bulbous portion ln the tendon and the tendon ls
then released from the clamp means, and whereln ad~acent clamp
means are spaced apart a flrst predetermlned distance apart
prior to forming the or each sald bulbous portlon, the flrst
predetermlned dlstance correspondlng to an unlnterrupted length
20~?~06
of tendon necessary to form a sald bulbous portion having the
correct or desired proportions.
BRIEF DESCRIPTION OF THE DRAWINGS
The present lnventlon will now be descrlbed, by way of
example, wlth reference to the accompanylng drawings, in which:-
figure 1 is a view of a rock anchor in accordance with the
present invention;
figure 2 ls an upper perspectlve view of a section taken along
the line 2-2 of Figure l;
figure 3 is a side view of a first embodiment of a machine for
manufacturing a rock another in accordance with the present
invention;
figure 4 is a plan view of a second embodiment of a machine for
manufacturing a rock anchor in accordance with the present
invention in a bulb upsetting condition;
figure 5 is a plan view of the machlne of flgure 4 in a tendon
dlsplacing condition;
flgure 6 ls a plan view of a third embodlment of a machine
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200Z8C)6
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for manufacturing a rock ~ncho~ in accordance with the
present invention in a bul~ upsetting conditlon;
Figuxe 7 is a transverse sectional view along li~es 7-7 of
Figures ~ to 6;
Fig~re 8 is a transverse sectional ~ie~ along lines 8-8 of
Figures 4 to 6; and
Figure ~ is a trans~erse sectional view along l~ne ~-~ of
Figure ~.
DESCRIPTION OF TRE INVENTION
Shcwn in Figures 1 and 2 is a rock ancho~ lU ~o~pr7 sing a
steel tendon 12. The tendon 1~ is composed of a plurality
o~ outer strands 1~ helically wound around a cent~e stran~
15 to form the tendon 12. As shown, there are six outer
strands 1~ wound around the centre str~nds. The tendon 1~
15 has a pluralit~ o~ bulbcus partio~s 16 spaced ap~rt from one
another along the length of the tendon.
The portio~s of ~he s~ra~ds 14 ~nd ~S, in the ~ulbous
portio~s 16, are spaced apart from each other around the
circum~erence of t~e bulbous portions 16, as shown. The
sect~o~ line 2-~ has ~een taken through the fattest part o~
the bulbo~s portion 16. As seen in Figure 2, the centre
strand 15 ls displaced a~ay fram the centre o~ the tendon
12. Each bul~cus porticn 16 has a ~ulb diameter de~i~ed as
the diameter of the smallest tube t~rough which the roc~
2~ anchor 10 will pass. The ~ulb periphery is indlcated b~ the
broken lines, m~r~ed 17 in Flgure 2. The outer strands 14
and the centxe stra~d 15 are all located ad3acent ~nd ~ithin
the bulb periphery 17.
This enables cement to contact a greater sur~ace ~rea of the
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strands 14 in use r as hereinbefore described. The rock
a~chor 10 is there~y firmly embedded in the cement.
Fur~hermore, the centre stxa~d 15 is displzced away from its
normal central pasiti~n, in the bulbous portions 16. When
the rock anchor 10 is stressed, ~he load will be t~ken moxe
evenly by the strands 14 and 15 th~n if the centre strand 1~
was in its central position. If the centre strand 15 was in
i~s centr~l position, more load would be taken b~ the centre
strand 15 tha~ ~he outer strands 14. This would then lower
the sa~e~ factor of the rock ~cho~ 10 wh~h co~ld then
fail a~ a much lower load.
Shown in Figure 3 is a ~irst embodiment of an apparatus 20
for ~anufacturing a rock anchor 10. The apparatus 20
compr~ses a plurality of spaced clamp means 22 ~o cl~mp the
tendon 12. The sp~cin~ between ~djacent clamp means 22 is
initially set at a first predetermined distance~ This first
predetermined leng~h corresponds to an uni~terrupted le~gth
of tendon 1~ necess~ry to form a ~ulbcus portion 16 having
the correct or desired propor~ions. The clamp ~eans 22 are
slidably mau~ted on a frame 24 suppor~ed by legs 26 and feet
27. One of the clamp means 22' is fixed to the frame 24.
As shown, the fixed cla~p means 22' is located at one end of
the ~r~me 24, in this case t~e 7 ~ft hand end, as shc)wn in
Figure 3.
Each clamp means ~2 co~prises an hydraulic ram 28 having a
plate 30 attached thereto to ~ea~ on and thereby clamp the
tendon 12 against an opposed ~}ate 32. Spr~n~s 34 are
provided to help bias the plates 30 a~d 32 apart when the
ram 28 is released. Each ram 28 ls supplied with hydraulic
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p~essure through a pipe 36 co~nected to a common mani~old 38
and controlled by a valve 40. Each clamp ~eans 22 is
provided with a stop 42 extending to the left, as shown, to
limit movement of ~he plu~alit~ of clamp means 22 relative
to e~ch othex.
A cl~mp d~splacement ~eans such as an hydraulic ram 44 is
fixed to the xight hand end of the frame ~4 ~nd is
controlled ~y a valve 4~. The ram 44 has a plunger 45 which
~ears on the clamp means 22 on the right, as shown in Figure
2. The ram 44 is able to displa~e the plurality of cl~p
~eans 22 relative to one another.
A~ hydra~lic power source 48 supplies hydraulic pressure to
the rams 28 and ~4 a~d is controlled ~y a valve 50.
ln use, a te~don 1~ is placed between the plates 30 and 32,
~5 of e~ch clamp means 22. The valves 40 and 50 are then
ope~ed to oper~te the rams 2~ The rams 28 move the plates
30 to bear on the tendon 12 and thereby clamp the te~don 12
against the opposed pl~tes 32.
The ~alve 46 is then opened to operate the ram 44. The ram
2~ 44 beaxs on the clamp means 22 on the right and displace~ it
tcwards the left. Since the clamp means ~2' i~ ~ixed to the
frame 24, the other cl~mp me~ns 22 are displaced relative to
one another. Such r~lative displacement causes the tendon
12 to be interrup~ed and the ~ul~ous portions 16 to be
2~ formed in the tendon 12, between adjacent clamp means 22.
Thus, i~ is apparent that the r~ht hand cl~mp 22 is moved
to the left as seen in Figure 3 kefore ~ny of the other
clamps 22 commence to move. This causes the first bul~ous
portion 1~ to ~e formed i~ the tendon 1~. Su~sequently the
2f'lr~2~0~
stop 42 o~ the right hand clamp 22 contacts the next clamp
2~ to the left~ Thus, the next clamp 2~ is caused to mov~
towar~s the left as seen in ~igure 3 and to cause the second
~ul~ous portian 1~ to be formed in the tendon 12. This
sequential ~ode o~ operaticn is continued until all of the
steps 42 are in contact with the next clamps 22 to the left
as seen in Fi~ure 3 and untll ~he left hand stop 42 contacts
~he fixed clamp 22'. Thus, the bulbous portions 16 are
prod~ced in se~uence by the sequential move~ent of t~e
clamps 22.
The stops 42 l~mit the displace~ent of one clamp means 22
relative to ad3acent clamp means 22. Conveniently, the
stops 42 l~mit the distance between a~ja~ent clamp means 22
to a second predetermined distance. This second
predetermined dist~nce corresponds to the bul~ous portions
16 reaching thei r co~rect or desired proportions.
~isplacement of the ram 44 is continued until bulbous
portions 16 of su~ficlent si7e and shape are formed. This
may occur when each stop 42 ~ontacts an adjace~t c~amp ~eans
20 22 and movement of the clamp mea~ 22 relative to one
another is no longer possible.
When the tendon 12 is axially compressed in the abo~e manner
to form the bu~bous portions 16, ~he strands 14 are forced
ap~rt and the strand 15 is forced out~ardly ~o a ~osition
2~ adjacent the bul~ periphery 17 as described above and a.rock
anchar 10 in accordance with the present inven~icn is
formed.
The valves 40 and 4~ are then closed. The springs 34 o~ the
clamp means ~2 urge the plates 30 away from the plates 32,
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thereby rele~sing t~e tendon 12. The ro~ a~cho~ 10 is then
removed and may ~e used in kncwn manner.
Shown ~ Figures 4, 5, 7 and 8 is a second em~cdiment of an
apparatus 52 for manufacturing a rock an~hor ~0. Reference
S numerals used in Figuxe 3 denote like parts in ~igures 4, 5,
7 and 8. As is apparent, there is only one slida~le clamp
means 22~ This clamp means 22 is held in a carriage 54
slidable along the frame 24. The hydraul~c ram 28,
associ~ted ~ith the fixed clamp me~ns 2~', is supplied with
~0 hy~raulic pressure through a P~pe 56. The ram ~8,
associa~ed ~ith the slidable colamp means 22, is s~pplied
with hydr2ulic pressure throush a separate pipe 58.
Si~ilarly, the ram 44 o~ the dispiacement means, has a
separate pipe 60 to supply hydraulic pressure~ The pipes
5~, 58 and 60 axe connected to an hydraulic ti~er ~not
shown) which co-ordlnates t~e act~o~ of both ~ams 28 2nd the
ram 44.
As shown, the tendon 12 passes through the cen~e of the ram
44. The plu~ger 4~ is at~hed ~o the plates 30 and 32 of
the fixed cl~mp ~eans 22, on the right z~ shown in Fig~re 4.
A straight pipe 61 is disposed to the left of the fi~ed
clamp 22 ~d is ~rranged to receive ~he rock anchor 10. The
pipe 61 has a d~dmeter at least th~t of the bulb diameter,
as defined herein~efore.
2S As seen in Figures 7 and 8, each pla~e 30 and 32 has a
recess 62. ~he plates 3C and 32 have a centralising ~i~ 64
located ~elow the recesses 62 and extendi~g between the
plates 3~ and 32. The pin 64 serves to support the ~endon
12 and to guide the plates 30 and 32 toward one another so
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thz~ ~he recesses ~2 clamp the tendon 12 therein. Th~s, the
plate 30 contains a recess (not s~own) which receives the
pin ~4 when the plates 30 and ~2 are moved together by th~
ram 28.
In use, a ten~on 12 is flrst fed through the r~m 44, between
the plates 30 and 32, of the c~amp means 2~ and 22', ~nd
into the pipe ~1.
The hydraulic timer operates and activates the ram 28, of
the ~ixed cl~pin~ means 22'. This results i~ the clamping
means 22' securely holding t~e tendon 1~ by means of the
pl~tes 30 and 32.
At this poi~t, the rzm 28, of the s~idable clamp means 22,
is deactiva~ed to a~l~w the tendon 12 ~o slide between its
plates 30 a~d 32.
The r~ 44 is then acti~ated and causes the plunger 45 to
move t~ the left, toward the fixed clamp means 22'. This
mo~7es th~ carria~e 54, with th~ sli~hle ~lAm~ m~n~ ~, t.
the left, toward the fixed clamp means 22'. When ~he
dista~ce ~etween the clamp ~eans 22 and 22' reaches the
first predetermined length as de~ined he~einbefore, the ram
44 is deactivated.
The ram 28, of the slidable clamp means 22, is then
activated to cl~mp the tendon 12 between the plates 30 and
32.
The r~m 44 is the~ reactivated. This causes the plunger 45
to b~:ar upon the pleLte9 3 0 and ~ ~, of the slid~ble cl~mp
means 22, and displace the slid~le clamp means 22 towards
the fixed clamp means 22'. Such re~a~i~e displacement
causes the ~ul~cus portions 1~ ~o ~e formed in the tendon 12
200Z806
g
between the clamp means 22 z~d 22'.
When the distance between the clamp means 22 and 22' reaches
the secon~ predetermined distance ~as defined hereinkefore~
the ram 28, of the slida~le clamp means 22, and the ram 44
are t~e~ deactivated to release the te~don 12.
The ram 44 then withdraws the plunger 45 a~ay fxom the fixed
clamp means 22'. This ~o~es the carriage 54 wi~h the
slidable c~a~p means 22, to the right, away from the fixed
clamp me~s 22'.
The r~m 28, of the slidable clamp means 22, is ~hen
~ctivated ~o clamp the tendon 12 by mea~s o~ the plates 30
and 32.
The ram 28, of the f~xed clamp means 22', ls then
deactivated to re~ease the tendon 12.
The ram 44 is the~ a~tivated, the p}~nger 45 exten~s and
moves the carriage 54 and slidable clamp means 22 towards
the fixed clamp means 22'. Thus, in this ccndition, the
slid~e clamp means 22 and the ram 44 ~unction as a te~don
dlsplacement means to mo~e the tendo~ 12~ This also moves
~0 the rock anchor 10 to the le~t and into the straight pipe
~. The pipe 61 generally straighte~s out any bends that
may h~ve occurred ~hen the bulbous ~ortion 16 was formed.
When the rock anchor 10 has been moved a distance equal to
the spacing ~etween adjacent bulbou~ portions 1~, ~he ram 44
is then deactivated to p~event any fur~hex movement o~ ~he
tendon 12.
The ram ~8, of the fixed clamping means 22' is then
activated a~ the process is repeated as many t~es as is
required.
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Shown in Figur~s ~ and 9 is a third embodiment of an
apparatus 66 for manu~ac~ux7 ng a rock a~chox 10 ~hich is a
modifica~ion of the apparatus 52 of Figures 4, 5, 7 and 8.
Like numerals denote like parts. The apparatus 66
additio~ally comprises a tendon displacement means 68 to the
right of the slidable clamp me~ns 22 in Figu~e ~. The
tendon displacement means ~ comp~ises a slida~le clamp
means 70 car~ied b~ ~ c2rriage 72 slidable along the frame
24. The clamp means 70 comprises an hydrauliC ram 74
supplied ~ith hydxaulic pressure hy a pipe 7~. The ram 74
h~s a plate 78 attached thereto to bear on and thereby ~lamp
the tendon 12 agains~ an opposed plate 80. Each plate 78
a~d 80 has a recess 8~, ln a similar manner to the maohine
52 of ~igures 4, 5, 7 and 8. ~he plates 78 and 80 have a
ce~tral~sing pin 84 loc~ted below the half recesses 82, in
si~ila~ manner to the machi~e 52 of Figures 4, 5, 7 and 8.
The tendon displ~emen~ means 68 further comprises a clamp
displa¢ement ~eans in the form of an hydraulic ram 86
supplied with hy~rauliC pressure through a p~pe 88. The ram
~ has ~ plunger gO which ~ears on ~he carriage 72 and is
arranged to displace the sliding ~lamp means 70 to the 1e~t,
as shown in Fig~re 6.
As is a~parent, the tendon displacement means 68 is a
separate item, as compared to ~he tendon displacement means
o~ the appaxatus 52.
The pipes 58 an~ 60 are connected to a ccmmon mani~old ~2
supplied with hydraul~c pressure by a pipe 94~ ~hus, the
f~xed clamp means 22 t ~d the slidable clamp mea~s 22 are
activated simultanecusly.
.. . , .. . _ .. . . . . . ..
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}n use, a tendon 12 is fi~st fed through between the pl~tes
78 and 80, through the ram 44, between the pl~tes 30 and 32,
of the clamp means 22 and 22l and lnto the plate ~1.
An hydraulic t~mer operates and simulta~eausly activates
both of the rams Z8 so that the clamps 22 and 22' securely
hold the tendon 12.
At this poi~t, the ram 86 is reactlvated to al~ow t~e tendon
12 to slide between the plates 78 and 80. Further, at this
stage, the clamp means 22 and 22' are the firs~
predetermined dl'stan~e ~as defined hereinbefore~ apa~.
The r~m 44 is then activ~ted to move the c~rriase 54 to the
le~t, towa~ds the fixed clamp means 22'. This relative
displacement in~errupts the tendon 12 and for~s a bulbous
portion 1~. When the distance between the clamp means ~2
and 2~' reaches the second predetermi~ed dist~nce (as
defined hereinbefore) both rams ~8 ~nd ~he ram 44 are
deactivated.
Ram 74 is ~hen activated so that the tendon 1~ is securely
hel~ in the slidable clamp means 70 by the plates 7~ and 80.
The r~m ~ is then ~ctivated and the plunger 90 moves the
carria~e 72 to the left, towards the fixed clamp means 22'.
This also moves the rock anchor 10 to the left and intc the
straigh~ pipe ~1.
When the ~ock ~nchor 10 has been moved a d}s~ance equal to
the spacings between adjacent bul~ous portions 1~, the ~ams
74 and 86 are deactivated.
~oth rams 28 are then simul~aneously activated and the
process ~s repeated as many times as desired.
T~e present invention provides a rock anchor which is easily
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manufactured and dGes not require un~avellln~ of the
strands, and more roGk anchors may be produced i~ the same
time as compared to priox ~t systems.
With ~he rock anchor of the present inve~tionr the strands
in the bul~ous portions are separated a~d he~ce the rock
anchor will ~e firmly e~bedded in t~e cement in the bore
hole.
Finally, it is envisaged ~hat the tendon displacement means
may alternate~y comprise an electric motsr driving a wheel.
An idler wheel would bea~ upon the driven wheel and the
tnedon would pas~ betwee~ the id~er ~nd driven wheels. A
timer would acti~ate an electric ~otor to rotate the driven
wheel and thereby mcve the tendon.
Modific~tions and variations such as wauld ~e appare~t ta a
skilled addressee are deemed within the scope of the preser.t
inve~tion. For example, there may be a num~er of each of
the machines 2~, S~ and 6~ operating simult~neou~ly together
in parallel. Further, the machine 20 may be provided wit~ z
~ydraulic timer to co-ordinate the ~c~ivation o~ the rams 2
and 4~. Even furt~er, the ram 44 may have an ad~ustment
~eans in the ~orm cf a t~readed column to vary the position
cf the ram 44 along the f~ame.
