AU785234B2 - Rock bolt installation - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventor: Address for Service: Invention Title: Details of Associated Provisional Applications: f OKiIKNSONW OLDE ryLNNES INDUSTRIAL ROLL FORMERS PTY LIMI1TED JEFFREY ROBERT FERGUSSON C.r"Wf Old et SoKr) Patent Trade Mark Aftcmys Lzel~ (o hevel 3, 20 Alfred. Stree~t its p ldyeA s1t 1 d Rock Bolt Installation 22. 10(2) k PR4281, 6 April 2001 The following statement is a full description of this invention, including the best method of performing it known to us: Rock Bolt Installation Field of the Invention The present invention relates to the installation of rock bolts and, in particular, to the installation of either resin or cermentitious grout which is intended to surround the bolt in the hole drilled for the bolt and provide good keying between the rock and the bolt.

Background Art °o There are several different methods by which the resin or grout is positioned within the hole.

S°.i :One method is to pump liquid grout into the hole. Another method is to insert an elongate two part resin filled container ("sausage") into the hole. The sausage has a diameter slightly less than the hole and is subsequently ruptured by the insertion of the rock bolt. This thereby mixes 15 the two resin constituents contained in the sausage and in this way causes the resin to set around the bolt. The present invention is concerned both with the insertion of such sausages and with the pumping of grout.

In different forms of mining activity different insertion techniques are used. For example, in coal mining the resin sausage is often inserted by hand. In some civil engineering tunnelling activities the resin sausage is held in a tubular mechanical insertion device such as a plastic tube.

In metalliferous mining two distinct types of machinery have hitherto been used. One type of machinery is a drilling machine which is used to drill holes in the ore. Explosives are then inserted in the holes to blow the ore into pieces which can then be removed. Such drilling machines are termed JUMBOS.

The other type of machine is a rock bolting machine, known as ROBOLTERS. These machines are special purpose machines which drill holes in the roof of the mine and subsequently insert a rock bolt in each drilled hole. These purpose built machines are incapable of face drilling, are expensive and include a carousel or other indexed equipment which is designed to enable the hole to be drilled by a drill bit, the drill bit extracted, the carousel rotated, one or more resin sausages inserted into the hole, the carousel rotated again, and the rock bolt inserted into the sausage containing hole. This operation relies upon expensive indexing machinery to accurately align the resin inserting apparatus and the rock bolt inserting apparatus with the previously drilled hole. The resin inserting apparatus is an integral part of the rock bolting machine.

The resin inserting apparatus of such rock bolting machines include mechanical arrangements where a flexible elongate member such as a spring is used to push a sausage through a flexible S. tube, and a pneumatic insertion device. The pneumatic insertion device essentially consists of a i' tube or gun which fires a sausage at the previously drilled hole relying on the indexing for accuracy. The sausage is propelled by compressed air provided by a substantial compressor 15 carried by the rock bolting machine.

This method of resin sausage insertion is sometimes inaccurate if the indexing is not reliable.

This results in the sausage not entering the hole but instead being broken against the roof of the mine. This can result in resin fouling the hole, sometimes to the extent that the hole must be redrilled or a fresh, adjacent hole drilled. For this reason the rock bolting machinery carries a supply of water which can be used to wash away resin debris (hopefully before it sets).

Historically, the coal mining industry was the first to use rock bolts and the standard in the coal mining industry was to drill a 27mm nominal diameter hole and to use a 22mm nominal shaft diameter rock bolt. This gave a nominal clearance between bolt and hole of 2.5mm which was filled with resin. For this purpose a standard sausage of 25mm diameter was produced and used in large numbers.

In "hard rock" metalliferous mining, the same 22mm nominal shaft diameter rock bolt was used, and the same 25mm resin sausage was used but a slightly larger hole of 32mm nominal diameter was drilled. This gave an annular clearance between the rock bolt shaft and the interior of the hole of 5mm which was regarded as the maximum permissible whilst still retaining adequate keying between the rock bolt shaft and the hole after the resin had set. One advantage of the larger hole was that it was more tolerant of small indexing errors. Since the hole diameter was 32mm and the external diameter of the tip of the pneumatic gun was approximately 35mm, the gun was merely aimed at the hole there was no intention that the gun be inserted into the hole.

In the processes used with cermentitious grout, a CT bolt or combination tube bolt is used. This 10 bolt consists of an elongate shaft having a mechanical anchor at its tip and a threaded portion at oooo its base. The base includes a hollow sphere or dome having an aperture which enables the dome to pass over the base. A short length of metal tube leads from the dome and is co-axial with, and externally surrounds, the shaft. The dome also includes a grout injection hole. A plastic tube surrounds the shaft and extends from the short metal tube nearly to the anchor.

S. Once the hole is drilled the CT bolt is inserted and a nut threadably engaged with the base. This nut tensions the shaft and activates the anchor. In addition the nut bears against the dome which drives the dome into the open end of the hole to close off the hole. Once this tensioning of the CT bolt has taken place, grout (which has the consistency of toothpaste) is pumped into the grout injection hole from a hose which is manually inserted into the hole.

The grout then travels between the shaft and tube to the far end of the blind hole where it surrounds the anchor. Then the grout passes back over the exterior of the tube to progressively fill the hole. Finally grout squirts out from around the dome to indicate to the operator that the grouting is complete. This also often results in the operator being covered with grout.

This grouting step is normally carried out in a separate action at a later time than the time at which the drilling and bolt insertion/tensioning took place. This is a substantial disadvantage since if something goes wrong with the grouting procedure it may be necessary to call the drilling team back to drill an additional hole and insert a further bolt before the grouting personnel can return to grout the additional bolt.

Object of the Invention For many years metalliferous mine owners have felt the desire to avoid the cost of rock bolting machines by hoping to be able to use their existing JUMBO drilling machines to not only drill the holes for rock bolts (which they are already capable of doing) but also to utilize these machines in the installation of the rock bolts themselves. The present invention seeks to address these desires by the provision of an attachment to a drilling machine. In one form this attachment allows the machine to also insert one or more resin sausages in the holes drilled by such machines before the rock bolt is inserted. In another form the attachment allows grout to be pumped into the hole after the rock bolt has been inserted.

The aim of the first form of the present invention is to provide a method and apparatus for injecting a resin containing sausage into a blind drilled hole in a rock or mineral surface prior to •insertion of a rock bolt into the hole, and which to at least some extent ameliorates the abovementioned difficulties with the prior art.

20 Summary of the Invention In accordance with the first aspect of the present invention there is disclosed, a method of injecting a resin containing sausage into a blind hole drilled in a rock or mineral surface prior to insertion of a rock bolt into the hole, said method comprising the steps of:loading said sausage into a supply conduit having a nozzle at its leading end, said nozzle including at least one fluid escape aperture located rearwardly of the tip of said nozzle; moving said nozzle forwardly to enter said tip into said hole; accelerating said sausage to move same along said supply conduit towards said nozzle by supplying fluid under pressure to said conduit behind said sausage; preventing any build-up of pressure within said hole by permitting escape of fluid from said hole as necessary via said escape aperture(s); injecting said moving sausage at speed into said hole via said nozzle whilst maintaining said tip inserted in said hole; venting said fluid under pressure from said supply conduit via said escape aperture(s) after said sausage passes therepast; and retracting said nozzle from said hole to permit insertion of said rock bolt into said hole.

In accordance with the second aspect of the present invention there is disclosed an apparatus to inject a resin containing sausage into a blind hole drilled in a rock or mineral surface prior S. to insertion of a rock bolt into the hole, said apparatus comprising: a drilling arm pivotably movable relative to a drilling machine to drill said hole, said drilling arm having a first surface carrying a reciprocally mounted drill, a nozzle reciprocally mounted on a second surface of said drilling arm and 25 movable along an axis substantially parallel to that along which said drill i reciprocates, said nozzle including at least one fluid escape aperture located rearwardly of the tip of said nozzle; a reciprocal motion actuator mounted on a third surface of said drilling arm and supporting said nozzle by bracket means interconnecting said nozzle and actuator; a fluid supply conduit at least part of which is flexible and which interconnects said nozzle and a pressurised fluid supply means, and sausage entry means located adjacent the end of said supply conduit remote from said nozzle.

In accordance with the third aspect of the present invention there is disclosed an accessory for a drilling machine having a drilling arm, said accessory comprising items inclusive of said above apparatus.

In accordance with a fourth aspect of the present invention there is disclosed a nozzle for injecting resin sausages into a blind hole drilled in a rock or mineral surface prior to insertion of a rock bolt into said hole, said nozzle comprising a thin walled hollow substantially cylindrical tip, a nozzle body having a tapered interior bore the narrow end of which is flush with the interior of said tip, and at least one aperture formed in the body of said nozzle and 20 venting said bore to atmosphere, each said aperture being inclined to the axis of said bore to Spresent a non-snagging edge to a resin sausage passing through said bore towards said tip.

Brief Description of the Drawings *25 A preferred embodiment of the present invention will now be described with reference to the Sdrawings in which: Fig. 1 is a schematic perspective view of a prior art drilling machine which has been modified by the apparatus of the preferred embodiment, Fig. 2 is a perspective view of the drilling arm of the machine of Fig. 1 showing the nozzle and supply conduit of the preferred embodiment, Fig. 3 is a side elevation of the apparatus of Fig. 2, Fig. 4 is a plan view of the apparatus of Figs 2 and 3, Fig. 5 is a perspective view of the apparatus of the attachment illustrated in Figs 2 4, Fig. 6 is a schematic view of the fluid supply conduit, fluid supply and sausage entry arrangement of the preferred embodiment, Fig. 7 is a longitudinal cross-sectional view of a hole and inserted nozzle tip, Fig. 8 is a view similar to Fig. 2 but illustrating the preferred embodiment of the nozzle of the grouting form of the present invention, and Fig. 9 is a schematic view similar to Fig. 6 but illustrating the preferred embodiment of the grouting form of the present invention.

Detailed Description of the Drawings As seen in Fig. 1, a drilling machine 1 of known construction is illustrated in a mine. Typical rock drilling machines 1 are termed JUMBOs. The drilling machine 1 has a body 2 supported by wheels 3 and is provided with a proximate arm 4 and a distal arm 5. A flexible fluid supply conduit 6 extends alongside the arms 4, 5 as will be described in more detail hereafter.

The arms 4,5 are articulated and movable under hydraulic control so as to permit movement of the distal arm 5 (which carries a reciprocally mounted and rotatable drill bit, well known in the art but not illustrated in Fig.l 1) so as to permit the drill bit to drill holes in either the roof, walls or floor of the mine. As indicated in Fig. 1, the drilling machine 1 is operated by a human operator 8 who is normally highly skilled and highly paid. The machine 1 also carries with it S 20 all the necessary supplies such as drill bits 9 to enable the drilling procedures to be carried out.

S Thus the space for such supplies and ancillary equipment is at a premium.

Turning now to Figs 2 4, the leading end of the distal arm 5 is illustrated and takes the form a beam of generally of H-shaped constant cross sectional shape and is provided with a rubber buffer 11 at its free end. A primary function of the distal arm 5 is to carry a rotatable drill bit (not illustrated) which is longitudinally reciprocal along side the arm 5 and passes through an apertured guide 12 adjacent the buffer 11. Reciprocally mounted alongside the arm 5 is a nozzle 13, a rigid supply tube 14 and the flexible hose or conduit 6. The nozzle 13 is provided with a number of circumferentially spaced apertures As best seen in Fig. 5, the nozzle 13 is held in a rigid L-shaped bracket 16 which extends from a U-shaped slide 17 which is reciprocal along the arm 5. The slide 17 is movable by means of an hydraulic cylinder 18 which is fixed to the arm 5 by means of a support lug 19. The supply tube 14 slidingly passes through a support sleeve 20 which is rigidly held to the arm 5 by means of a mounting plate 21.

The positioning of the hydraulic cylinder 18 and support lug 20 on that side of the arm opposite from the drilling arrangements of which only the apertured guide 12 is illustrated, means that the hydraulic cylinder 18 is in a substantially protected position notwithstanding the harsh environment in which it operates.

°o S •It will be appreciated that the above described arrangement results in the nozzle 13 being longitudinally reciprocal along the arm 5 under the control of the hydraulic cylinder 18 so as to be movable between a forward position illustrated in Figs. 3 and 4 in which the nozzle 13 projects beyond the buffer 11, and a retracted position illustrated in Fig. 2 where the nozzle 13 is withdrawn behind the buffer 11 and is therefore protected by it.

Turning now to Fig. 6, the overall arrangement of the resin injecting apparatus is illustrated.

The supply conduit 6 is connected to a loader 24 which is provided with a one way flap valve 20 25 and a funnel shaped opening 26 through which resin sausages 27 can be loaded into the conduit 6. Upstream of the loading arm 24 is a solenoid operated air valve 28 which is connected to a regulator 29. The valve 28 is supplied by a compressor 31 which takes air from the mine through a filter 32. Optionally an accumulator 30 is provided. Instead of the compressor 31 a mine supply 39 of compressed air can be used instead in some mines.

The loader 24, air valve 28, regulator 29, accumulator 30, compressor 31 and filter 32 are all carried the body 2 of the rock drilling machine 1 so that the funnel shaped opening 26 is accessible to the operator 8. A water supply 23 and water control valve 22 are also connected to the loader 24 to permit it and the conduit 6 and nozzle 13 to be washed clear of any debris from time to time.

Since the compressor 31 must be carried by the rock drilling machine 1, the compressor 31 is relatively small and thus is capable of generating a pressure only of the order 7 bar (100 psi).

In operation, the compressor 31 operates continuously and thus there is no need to regulate the pressure being supplied to the valve 28. However, the regulator 29 is instead provided on the downstream side of the valve 28 and is connected "back the front" from what one might expect in that the input pressure to the regulator is supplied from the downstream side of the valve 28 as schematically indicated by feedback pipe 34 in Fig. 6.

In operation, after a blind hole 35 has been drilled in the rock surface 36, the drilling bit (not illustrated) is retracted in conventional fashion. If necessary the arm 5 is rotated about its longitudinal axis, or otherwise moved so that the nozzle 13 is aligned with the hole 35. Then the nozzle 13 is extended so as to enter the blind hole 35 but with the apertures 15 remaining clear of the rock surface 36. Then a sausage 27 having a cable tie 33 is passed into the funnel shaped opening 26 and past the one way valve 25 so as to lie at the machine end of the conduit 6. The purpose of the plastics cable tie 33 is to permit a friction fit to be created between the sausage 27 and hole 35 after insertion. Since the sausage 27 is soft and deformable, within the conduit 6 the cable tie 33 lies within the nominal dimensions of the sausage 27.

S- 20 Thereafter the air valve 28 is opened so as to supply compressed air to the machine end of the S. conduit 6. This simultaneously closes the one way valve 25 and begins to move the resin sausage 27 towards the nozzle 13. It will be appreciated that the sausage 27 functions as a leaky piston within the conduit 6 and thus begins to accelerate along the conduit 6 towards the nozzle under the influence of the compressed air. Some of this air leaks past the sausage 27 but does not pressurise the hole 35 since the air is able to escape via the apertures 15 as indicated in Fig. 6.

As a consequence, there is no air pressure above atmospheric in advance of the sausage 27 which accelerates down the conduit 6, into the supply tube 14 and through the nozzle 13 to be injected into the hole 35. This injection takes place with sufficient velocity for the sausage 27 to reach the end of the hole 35. The operator 8 is able to observe the successful injection of the sausage 27 into the hole 35 by the escape of air in large volumes through the apertures This puff of escaping compressed air indicates to the operator 8 that the air valve 28 should be shut. If necessary, a subsequent sausage 27 can then be loaded through the opening 26 to pass beyond the one way valve 25 and into the machine end of the conduit 6. The procedure is repeated for as many sausages as are required. Then the nozzle 13 can be retracted and the rock bolt (not illustrated) can be inserted into the hole 35 in conventional fashion.

Because of the limited capacity of the compressor 31, during the injection of a succession of sausages 27, the pressure supplied to the valve 28 steadily decreases. Since the pressure regulator 29 is sensing the pressure of the outlet of the valve 28, for each successive sausage the regulator 29 permits more air to pass into the conduit 8 to compensate for the falling pressure of that air. In this way the injection speed of the successive sausages 27 is not reduced by as much as the reduction in pressure upstream of the valve 28.

o o° Turning now to Fig. 7, the preferred dimensions of the hole 35 and nozzle 15 are illustrated schematically. The hole 35 is drilled in the rock surface 36. In the upper part of the hole 35 is illustrated the shaft of a rock bolt 37 which is surrounded by resin 38. That is, the upper part of Fig. 7 illustrates the situation after insertion of the rock bolt 37. The rock bolt 37 has a S 20 nominal shaft diameter of 22mm (the diameter of 38mm indicated in brackets refers to a different size arrangement to be described hereafter). The hollow cylinder of set resin 38 has a wall thickness of from 2 to 5mm and preferably not greater than 5mm. Thus 22+5+5=32mm is the nominal diameter of the hole The nozzle 13 has a replaceable thin walled hollow cylindrical tip 40 which is threadably engaged with the body of the nozzle 13. The tip 40 is case hardened to reduce the likelihood of the tip 40 being damaged during the insertion process. Even so they are damaged and need to be replaced from time to time.

The outer or external diameter of the tip 40 is 30mm thus allowing a 1 mm annular clearance between the tip 40 and the hole 35. The wall thickness of the tip is only 2mm thus providing an internal diameter of 26mm for the tip 40. This allows a 0.5mm annular clearance between the tip 40 and the 25mm resin sausage 27 (indicated by dashed lines in Fig. The nozzle body and conduit 6 has an internal diameter of 32mm thus allowing the sausage 27 to move freely therealong and some air to escape therepast.

The holes 15 are rearwardly inclined as illustrated in Fig. 7 so that the forward edge of the hole 15 in the tapering inner surface 41 of the body of the nozzle does not present a snagging edge to the sausage 27. This would be the case if the holes 15 were drilled perpendicular to the longitudinal axis of the nozzle 13.

oooo In some applications, rock bolts of a larger shaft diameter are required. As indicated in brackets in Fig. 7, an alternative embodiment has a rock bolt 37 with a nominal diameter of 38mm. With the necessary clearance for the resin 38, this results in a hole diameter of 44mm.

°°As a consequence, the dimensions of the nozzle 13 need to be changed. With a 1mm annular clearance the outer diameter of the tube 40 can be set at 42mm. With the 2mm wall thickness for the tube 40 as before, this determines the inner diameter of the tube 40 at 38mm and thus a 36mm diameter sausage is appropriate. Any conveniently sized hose can then be used for the S. 20 conduit 6 and thus a conduit in the form of a standard hose having an internal diameter of is appropriate.

It will be apparent to those skilled in the art that the need to maintain standard rock bolt and hole size means that the nozzle dimensions and resin sausage dimensions must be carefully selected.

Further, the fact that the tip 40 of the nozzle is inserted into the hole 35 means that this action can take place under operator control and thus expensive and sometimes insufficiently accurate indexing mechanisms are not required.

In addition, the attachment can be provided to the drilling machine and it is thought that often this may mean that the cost of rock bolting machines, or possibly an additional rock bolting machine, can be avoided.

Furthermore, the reduced air supply requirements brought about by the provision of the regulator 29 means that the air supply can be provided by the relatively small compressor carried by the drilling machine or even, in some cases, by a mine air supply 39 (Fig. 6) delivered via flexible hose to the drilling machine.

Turning now to Figs. 8 and 9, a preferred embodiment of a second form of the present invention will now be described, the second form being concerned with securing the rock bolt -in situ with grout after the bolt has been tensioned. Thus a supply of liquid grout rather than individual resin sausages, is used. In the second form like parts to those used in the first form are allocated like numbers.

As seen in Fig. 8, the apparatus attached to the drilling arm 5 is essentially as before except that the air nozzle 13 is replaced by a grouting nozzle 113. The blind hole 35 drilled in the rock surface 36 is essentially as before however a CT rock bolt 137 is provided having a shaft an anchor 51 and a threaded base 52. A plastic tube 53 surrounds the shaft 50 and terminates in a metal tube 54 which extends into a hollow sphere or dome 55. The dome seats on a washer 56 and includes a grout injection hole 57 which leads into the hollow interior of the dome 55. A nut 58 tensions the rock bolt 137 and compresses the dome 55 and washer 56 against the rock surface 56.

When the grouting nozzle 113 is moved towards the rock bolt 137, the hollow interior of the nozzle 113 mates with the exterior of the dome 55 and effectively seals against it. However, the hole 57 communicates with the interior of the supply tube 14 and hose 6.

Carried by the drilling machine 1 is a drum 60 of grout which includes a mixing impellor 61 and mixer motor 62. The grout passes from the drum 60 into an auger style pump 63 which is driven by a motor 64.

After the hole 35 is drilled, the drill bit (not illustrated) is retracted and the rock bolt 137 is inserted into the hole 35. The drill bit is replaced by a conventional rotary spanner (not illustrated) and then engaged with the nut 58 to tension the rock bolt 137. Then the spanner is retracted and the grouting nozzle 113 moved forwardly to engage the dome 55. Then the motor 64 is operated to drive the grout through the hose or conduit 6, supply tube 14 and nozzle 113. The grout is then able to enter the hole 57 to pass through the tubes 54, 53 and thence to the end of the hole 35. When the grout has filled the hole 35 it squirts out around the So:. washer 56 and the operator stops the pump motor 64.

Then the grout nozzle 113 is retracted to finish the bolt installation cycle. The next hole can then be drilled, and so on. The cycle time for complete installation of a single rock bolt 137 is S-expected to be less than 5 minutes. In addition to this substantial time saving, the operator works under a secured mine roof and is not continually inundated with grout as in the prior art.

Further, if something does go wrong with the installation procedure then an adjacent hole can be drilled immediately and another bolt inserted and installed, without any personnel having to S 20 re-visit the site.

The foregoing describes only some embodiments of the present invention and modifications obvious to those skilled in the art, can be made thereto without departing from the scope from the present invention. For example, the drilling machine can have multiple arms 5 each of which is supplied with a corresponding attachment. Furthermore although compressed air is preferably used as the propelling fluid, a liquid such as water could be used instead but would not be so convenient.

The term "comprising" (and its grammatical variations) is used herein is used in the inclusive sense of "having" or "including" and not in the exclusive sense of "consisting only of'.

Claims (16)

1. 2. The method as claimed in claim 1 wherein steps and are repeated for each of at least one subsequent sausage to be injected into said hole without moving said nozzle.
2. 3. The method as claimed in claim I or 2 wherein said fluid is compressed air.
3. 4. The method as claimed in claim 1 or 2 wherein said fluid is water. The method as claimed in any one of claims 1-4 wherein said sausage includes a friction means to retain said sausage in said hole following injection of said sausage.
4. 6. The method as claimed in claim 5 wherein said friction means comprises a cable tie.
5. 7. The method as claimed in any one of claims 1-6 wherein the internal dimension of said °°supply conduit relative to said sausage creates a loose fit whereby said fluid can escape past said accelerating sausage.
6. 8. A method of injecting a resin containing sausage into a drilled blind hole in a rock or mineral surface prior to said method being substantially as herein described with reference to Figs. 1-7 of the drawings.
7. 9. An apparatus to inject a resin containing sausage into a drilled blind hole in a rock or mineral surface prior to insertion of a rock bolt into the hole, said apparatus comprising: a drilling arm pivotably movable relative to a drilling machine to drill said hole, said drilling arm having a first surface carrying a reciprocally mounted drill, a nozzle reciprocally mounted on a second surface of said drilling arm and movable along an axis substantially parallel to that along which said drill reciprocates, said nozzle including at least one fluid escape aperture located rearwardly of the top of said nozzle; a reciprocal motion actuator mounted on a third surface of said drilling arm and supporting said nozzle by bracket means interconnecting said nozzle and actuator; a fluid supply conduit at least part of which is flexible and which interconnects said nozzle and a pressurised fluid supply means, and sausage entry means located at the end of said supply conduit remote from said nozzle. The apparatus as claimed in claim 9 wherein said first surface is dorsal, said second surface is lateral with respect to said dorsal surface and said third surface is ventral o. with respect to said dorsal surface.
8. 11. The apparatus as claimed in claim 9 or 10 and comprising a drilling machine. So
9. 12. An apparatus to inject a resin containing sausage into a drilled blind hole in a rock or mineral surface prior to insertion of a rock bolt into the hole, said apparatus being substantially as herein described with reference to Figs 1-7 of the drawings.
10. 13. An accessory for a drilling machine having a drilling arm, said accessory comprising items inclusive the apparatus as claimed in any one of claims 9-11.
11. 14. The accessory as claimed in claim 13 wherein said first surface is dorsal, said second surface is lateral with respect to said dorsal surface and said third surface is ventral with respect to said dorsal surface. An accessory for a drilling machine having a drilling arm, said accessory being substantially as herein described with reference to Figs 1-7 of the drawings.
12. 16. A nozzle for injecting resin sausages into a blind hole drilled in a rock or mineral surface prior to insertion of a rock bolt into said hole, said nozzle comprising a thin walled hollow substantially cylindrical tip, a nozzle body having a tapered interior bore the narrow end of which is flush with the interior of said tip, and at least one aperture formed in the body of said nozzle and venting said bore to atmosphere, each said aperture being inclined to the axis of said bore to present a non-snagging edge to a resin sausage passing through said bore towards said tip.
13. 17. The nozzle as claimed in claim 16 wherein said tip is releasably engagable with said nozzle body.
14. 18. The nozzle as claimed in claim 17 wherein said tip is threadably engaged with said nozzle body.
15. 19. The nozzle as claimed in any one of claims 16-18 wherein said tip is metal and is case hardened. o i 20. A nozzle for injecting resin sausages into a blind hole drilled in a rock or mineral surface prior to insertion ofa rock bolt into said hole, said nozzle being substantially as herein described with reference to Figs. 2-7 of the drawings.
16. 21. A rock bolt secured by resin in a drilled blind hole in a rock or mineral surface and in which said resin is inserted by the method as claimed in any one of claims 1-8 or in wngo which said resin is inserted using the apparatus as claimed in any one of claims 9-20. o o go• Dated this 5th day of October 2006. rNDUSTRIAL ROLL FORMERS PTY LIMITED BY FRASER OLD SOHN Patent Attorneys for the Applicant S. S** S S OS S S S S S S 0 S. S 0 S S@