Note: Descriptions are shown in the official language in which they were submitted.
~`' . `~3
ROCK BOLTING
This invention relates to rock bolting as used in mining and
similar fields for placing and securing rock bolts. The
invention extends to a method for inserting rock bolts and
to apparatus for inserting rock bolts.
The technique of rock bolting is well known. ~t consists of
drilling a hole in a rock face, inserting a length of rod
i~to the hole (a so-called rock bolt3, securing the inner
end of the bolt in the hole and then securing the outer end
of the bolt against the rock face. This has the effect of
anchoring ~he rock face back to the rock at the depth of the
hole.
It is known to anchor the inner end of the rock bolt either
by using a mechanical anchor, or by inserting a settable
resin into the hole. The present invention is concerned
particularly with resin bonded bolts, but is also applicable
to mechanically anchored bolts.
It is known to mount a rock bolting head at the end of a
boom, so that by movement of the boom the rock bolting head
can be positioned at a range of different places and a
series of bolts can be put in place in accordance with a
pre-determined bolting pattern. It is necessary to carry
out three sequential operations in order to place a resin
bonded bolt; ie drilling the hole, inserting the resin and
placing and securing the bolt. In a known apparatus, the
rock bolting head includes a locating member which is first
locked into position against the rock face. A carriage
which supports a rock drill, a resin injection head and a
bolt supply unit is mounted relative to the locating member
for rotation about the axis of the locating member. The
apparatus is then operated by actuating the drill to drill
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30 October 19g1
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a hole, indexing the carriage about the axis of the locating
member until the injection unit registers with the hole
drilled by the drill, inserting the resin and then indexing
the carriage again until the bolt insertion unit registers
with the hole.
The known apparatus has two specific disadvantages.
Firstly, considerable accuracy is required in respect of the
indexing movement ahout the axis of the locating member if
the resin insertion and the bolt insertion are to reliably
line up with the hole drilled by the drill. The rock
bolting head is however operating under adverse conditions
and rock debris inevita~ly becomes trapped in whatever
bearing arrangement is used between the carriage and the
locating member. As a result, over the course of time the
bearing becomes worn and sloppy leading to inaccuracies.
Secondly, where the axis of the locating member is at riyht
angles to the rock surface, then th~ positions of the
injection unit and the bolt insertion unit will reliably
line up with the drilled hole (assumin~ no undue wear in the
bearings). However in the situation where the axis of the
locating member is not at right angles to the rock face,
then the reliability of positioning of the apparatus is
severely limited, and in some cases the apparatus cannot be
used at all because the injection and insertion units simply
do not line up with th~ drilled hole.
According to the invention, there is provided a method o~
inserting rock bolts, the method comprising the steps of
mounting a rock bolting h~ad which includes a drilling
station and a bolting station at one end of a boom, moving
the boom to position the dxilling station at the place where
a rock bolt hole is to be drilled, drilling a hole, moving
the bo~m to locate the bolting station below the hole
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30 Oc~ob~r 1991
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drilled by the drilling station and inserting a bolt in the
hole.
Preferably the rock bolting head also includes a grouting
station, and the method includes the steps of moving the
grouting station to register with the hole prior to the
movement of the bolting station to register with the hole.
According to a second aspect of the present invention, there
is provided rock bolting apparatus comprising a mobile
chassis and a boom, one end of the boom being mounted on the
chassis and the other end of the boom carrying a rock
bolting head, wherein the rock bolting head carries a
drilling station and a bolting station which stations are
mounted in a fixed position relative to one another with no
relative movement between the stations and the part of the
head which is mounted on said other end of the boom, and
wherein the boom is movable in slew, lift, and extend modes
under computer control.
Where the apparatus is to be used for placing resin bonded
bolts, then the rock bolting head will also include a resin
injection station. Resin injection is also referred to as
grouting.
2S
It has been found that it is possible with computer control
to position the remote end of a boom with very great
accurac~. According to the invention, this results from the
use of separate position transducers in each boom
joint/pivot point, signals from all of whi~h are fed back to
a central control unit. It is possible to programme the
control unit to carry out a selected sequence of movements.
It has ~een found that by using such computer control of the
boom, it is possible to entirely dispense with any movement
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30 October 191
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in the rock bolting head itself so far as the positioning of
the drilling station, the grouting station (if present) and
the bolting station are concerned.
The drilling station, the grouting station and the bolting
station will normally be arranged parallel with one another
within the rock bolting head, and preferably the grouting
station is arranged between the drilling station and the
bolting station.
The invention will now be further described, by way of
example, with reference to the accompanying drawings, in
which:
Figure 1 is a side view of rock bolting apparatus in
accordance with the invention, in position in a mine
tunnel;
Figure 2 is a plan view of the apparatus of Figure 1,
illustrating a possible rock bolting pattern;
Figure 3 is a detail view of a boom and a rock bolting
head in accordance with the invention;
Figure 4 is an end elevation of a rock bolting head in
accordance with the invention;
Figure 5 is a side elevation of the head of Figure 4;
3~ Figure ~ is a plan view of the head of Figures 4 and 5;
and
Figure 7 shows a resolver unit fitted at one of the
boom joints,
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30 October 1,,l
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Figure 1 shows a mine tunnel with a floor 10 and a roof 12.
A vehicle 14 mounted on crawler tracks 16 is positioned in
the tunnel. The vehicle is steered in a conventional
manner. The vehicle has a boom support 22 on which a boom 24
is mounted. The boom itself will be described in more
detail with reference to Figure 3. At the outer end of the
boom is a rock bolting head 26, and this head will be
described in more detail with reference to Figures 4, 5 and
6. Figure 1 shows two alternative positions of the head, Z6
and 26a, and the head can be positioned in either position
26 or position 26a, or indeed a variety of other positions
by appropriate control of the boom 24.
Figure 2 is a plan view of the same ~-ehicle 14, in position
between the two side walls 28, 30 of the mine tunnel. In
Figure 2, a network of roof bolt positions 32 is shown. In
order to stabilise a mine roof (or mine walls) it is
conventional to insert a number of bolts normally in a pre-
defined pattern such as the square grid shown in Figure 2.
Th~ boom 24 will be moved to each of the positions shown in
chain dotted lines, in order to insert a bolt at each
location 32.
Figure 3 shows the boom 24 in more detail. The boom has a
back plate 34 which will be rigidly fixed to the support 22
on the vehicle 14. The main boom tube 36 is mounted
relative to the plate 34 for rotation about a vertical axis
38 and about a horizontal axis 40. Movement about the axis
38 is controlled by a slew cylinder 42 and movement about
the horizontal axis 40 is controlled by a li~t cylinder 44.
Both the cylinders 42 and 44 are conventional double-acting
hydr~ulic piston/cylinder units connected between the boom
and the base plate 34.
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30 October 1991
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The main boom tube 36 supports, in a telescopic manner, an
inner boom tube 46 which can be extended from or retracted
into the main tube 36 by means of an internal piston/
cylinder unit (not shown in the drawings). At the outer end
of the boom a rollover unit 48 is mounted and this allows
rotation about the axis of the boom in a manner as
described, for example, in British patent specification 2
189 724. Finally, the rock bolting head 26 is mounted to
the end of the boom for rotation about a horizontal tilt
axis 50, and this movement is controlled by a hydraulic
piston/cylinder unit 52.
At each axis of rotation and at the interface between the
inner boom tube 46 and the main boom tube 36, a transducer
is mounted which monitors the movement taking place.
Signals from all these transducers are passed to a control
unit 53 on the vehicle 14. The control unit also sends
signals to the hydraulic system to direct boom movement.
By suitably programming the control unit 53, it is possible
for the rock bolting head 26 to be moved sequentially to a
series of pre planned locations where rock ~olts can be
inserted. If the control unit is programmed in this way,
then the apparatus need only be placed in a starting
position, and then the control unit can be responsible for
all movements of the boom and the rock bolting head which
are required to fix bolts at a series of different
positions. It may also be possible for the control unit to
contr~l movement of the vehicle 14 on the floor 10, to
enable a still more extensive pattern of bolts to be fixed.
Figures 4, 5 and 6 show the rock bolting head itself. The
head comprises a carriage 54 which is secured to the end of
the boom 24. On this carriage a rock drill 56 with a feed
~eam 5~ is mounted at one side and a rock bolt insertion
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30 Octobcr 1991
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unit 60 is likewise mounted on a ~eed beam 59 on the other
side. A tube 62 for injection of resin grout is also
provided. The rock drill 56 and the insertion unit 60 are
each of conventional construction, and their manner of
operation will be clear to those skilled in the art. The
insertion unit 60 may be associated with a magazine which
supplies rock bolts to the unit for insertion.
In use, the boom is first moved to a position where the axis
of the drill 56 registers with the location 32 where a rock
bolt is to be placed. The boom can be brought to this
position by operation of the control unit 53 or by operation
of manual controls. Whichever method of boom placement is
chosen, the transducers fitted in the boom will continue to
send ~osition signals back to the control unit, so that the
control unit at all times knows where the end of the boom
iS .
The drill 56 is then operated to drill a hole in the rock of
the necessary length. The drill is retracted, and a signal
is thereupon sent to the control unit which tells the
control unit to move the entire boom by a distance which
coxresponds to the distance between the a~is of the drill 56
and the axis of the injection tube 62. Depending upon the
position of the hole relative to the supports 22, this
movement may require any combination of the possible modes
of movement of the boom, ie lift, slew or extend. The amount
of movement required will be small because the distance
between the axis of the drill 56 and that of the tube 62 is
small, but it would be within the power of the computer
control to achieve this movement to a position where the
tube 62 registers with the hole drilled by the drill 56.
Resin grout is then injected into the hole in any
conv~ntional manner. After the injection stage has been
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completed, the boom is moved again to line up the axis of
the bolt insertion unit 60 with the hole so that a bolt can
be run into the hole and then, once the grout has secured
the bolt, the bolt can be tightened.
The movements to position the drilling station, then the
grouting station and then the bolting station beneath the
location 32 are all accomplished by movement of the boom
itself, rather than by movements within the rock bolting
head 26.
In place of resin bonded bolts, mechanically anchored bolts
can be used, and in this case the grouting tube 62 can be
omitted. Most known types of mechanically anchored bolts
can be used.
Figure 7 illustrates, by way of example, a transducer which
monitors the movement of the boom 36 about the axis 40. The
boom is mounted for pivoting movement on a pin 64. The pin
is secured to a bracket 66, and a resolver unit 68 has a
part which is fast with the main boom tube 36. When the
boom tube 36 moves about the axis 40, there is relative
rotation between the parts 66 and 68 and this is detected by
a resolution detector 70. A signal is then sent along a
line 72 to the control unit 53. Resolver units 70, or
transducers, are well known in the art and any conventional
unit which is suitable for use in a mining environment can
be used. The type of transducer required to monitor the
sliding movement between the inner boom tube 46 and the main
boom tube will also be readily apparent to one skilled in
the art.
The invention thus provides an accurate method of
positioning rock bolts in a rock wall which avoids the need
for any moving parts in the positioning mechanism at the
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location where the drilling for the rock bolt hole is
carried out. This leads to simplification of the rock bolt
head, and improved accuracy of registration between the
drilling station, the grouting station and the bolting
station.
SP832 . CA
30 October 1991
