AU2021206917A1 - Resin-Grouted Rock Bolt Assembly with an Adapted Sealing Bush - Google Patents

Abstract

A single-use sealing bush which is adapted to form a sealing interface between a rock bolt and a nozzle of a grout delivery system, the sealing bush including a cylindrical body defined between a first end and a second end; a hole in the first 5 end of the body that is adapted to receive the rock bolt; a pair of spaced apart annular ridges, on an outer cylindrical surface of the body, between which a grout distributing channel is defined; and an aperture which connects the channel to the recess; wherein each annular ridge is adapted to seal against the nozzle in a position which communicates a grout inlet port of the nozzle with 10 the grout distributing channel. 15 1/6 2 16 22 15 15 12 26 24 14 10 24 10 34 48 44 48 20 62A 62B62A 45 62A 620 56 FIGURE 6 FIGURE 2

Description

1/6 2 16

22

15

12 15 26

24 14

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48 44 48 20

62A 620 62A 62B62A 45

56 FIGURE 6 FIGURE 2

P/00/011 Regulation 3.2 AUSTRALIA

Patents Act 1990

COMPLETE SPECIFICATION FORASTANDARDPATENT ORIGINAL TO BE COMPLETED BY APPLICANT

Invention Title: Resin-Grouted Rock Bolt Assembly with an Adapted Sealing Bush

Name of Applicant: Innovative Mining Products (Pty) Ltd

Address for Service: A.P.T. Patent and Trade Mark Attorneys PO Box 833, Blackwood, SA 5051

The following statement is a full description of this invention, including the best method of performing it known to me/us:

RESIN-GROUTED ROCK BOLT ASSEMBLY WITH AN ADAPTED SEALING BUSH BACKGROUND OF THE INVENTION

[0001] The invention relates to an improvement or modification to, or

development on, a resin-grouted rock bolt assembly as described in the

specification to Australian patent application no. 2020386991, which

specification is herein incorporated by reference.

[0002] Resin-grouted rock bolt assemblies are well known in the art. Such

assemblies typically include a resin inlet adapter, or the like, which is engaged

to a proximal end of a rock bolt, positioned to feed a resin into a resin conduit

provided by a bore formed through the bolt or a sleeve or conduit which fits

around the rock bolt, providing an annular conduit.

[0003] The adapter is adapted to receive a resin material from a grout delivery

source and to channel the resin through the bore or the annular conduit.

[0004] The problem with such assemblies is at least two-fold. Either the

adapter or the resin-tight seals, provided between the adapter and the bolt or

the sleeve, are aligned in the line of action of the installation force. With respect

to the adapter, this prevents a strong installation force being applied to the

proximal end of the bolt, to avoid damage to the adapter, and with respect to

the seals, this causes compressive damage to the seals.

[0005] Hereinafter, the term "grout" or "resin" is used interchangeably to mean

any adhesive material which is introduced into the rock hole to adhere the rock bolt within the rock hole.

[0006] The invention at least partially sources the aforementioned problem.

SUMMARY OF INVENTION

[0007] The invention provides a rock bolt assembly which includes:

an elongate bolt which extends between a distal end and a proximal

end;

a tubular sleeve which longitudinally extends between a leading end

and a trailing end, on the bolt such that at least a proximal end

portion of the bolt projects from the trailing end of the sleeve; and

a nozzle docking bush on the proximal end portion between the

trailing end of the sleeve and the proximal end of the bolt, the bush

having a cylindrical body defined between a first end and a second

end, a central hole formed through the body between the ends, a pair

of spaced apart annular ridges on an outer surface of the cylindrical

body, a grout distributing channel between the annular ridges, and an

aperture in the channel which communicates the channel with the

hole;

wherein the central hole includes a leading portion which ends at the

first end and which is adapted to receive the trailing end of the sleeve

in sealing engagement, and a trailing portion which ends at the

second end and which is adapted to sealingly engage the bolt; and wherein each annular ridge is adapted to seal against a nozzle of a grout delivery system; thereby to provide, on engagement of the nozzle with the bush, a sealed grout passage defined by the grout distributing channel, the aperture, the central hole and an interior of the sleeve.

[0008] The leading portion of the central hole may include a formation against

which the trailing end of the sleeve is press-fitted in sealing engagement.

[0009] The formation may be an annular ridge or an annular recess.

[0010] The trailing portion of the central hole may be formed with threads to

engage complementary threads on the proximal end portion of the bolt.

[0011] Alternatively, the trailing portion may be adapted to friction fit over the

proximal end portion.

[0012] In either alternative, the second end of the bush may be positioned

flush with the proximal end of the bolt. Preferably, the second end is fixed to the

proximal end by any suitable method such as, for example, welding.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The invention is further described by way of examples with reference to

the accompanying drawings in which:

Figure 1 is a view in elevation of a rock bolt assembly, in accordance with the

invention, and a nozzle of a grout delivery system disengaged from the assembly;

Figure 2 is a view in longitudinal section of the rock bolt assembly and the

nozzle of Figure 1;

Figure 3 is a view in elevation of the rock bolt assembly of Figure 1 with the

nozzle engaged with the assembly;

Figure 4 is a view in longitudinal section of the rock bolt assembly and the

nozzle of Figure 3;

Figures 5A and 5B respectively illustrate, in perspective and in section

respectively, a first embodiment of a nozzle docking bush of the invention;

Figure 6 illustrates a second embodiment of a nozzle docking bush of the

invention;

Figures 7A and 7B respectively illustrate, in perspective and in section

respectively, a third embodiment of a nozzle docking bush of the invention;

Figure 8A and 8B illustrate, in longitudinal section, the rock bolt assembly, with

the nozzle in accordance with the second embodiment, being inserted into a

rock hole; and

Figure 9 is a view in perspective of a proximal end of the rock bolt assembly.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0014] Referring to Figures 1 to 4 of the accompanying drawings, a rock bolt

assembly 10 is provided in accordance with the invention. The assembly is

adapted to engage with a grout nozzle 11 at a leading end of a grout delivery

system (not shown).

[0015] The assembly includes a rock bolt 12 having an elongate rod-like

cylindrical body 14, which is adapted with paddle anchors 15, and which

extends between a distal end 16 and a proximal end 18. In this example, the

body has a threaded end section 20 which extends from the trailing end.

[0016] The assembly 10 includes an elongate sleeve 24 which extends

between a leading end 26 and a trailing end 28. The sleeve is adapted to

receive the rock bolt 12 with the distal and proximal ends (16, 18) of the bolt

extending beyond the leading end and the trailing end (26, 28) respectively of

the sleeve. The sleeve is held in position, on the bolt 12, at least by frictional

abutment of the leading end with an adjacent paddle anchor 15, which anchor

extends beyond the circumferential dimension of the bolt body 14.

[0017] The assembly 10 further includes a nozzle docking bush 30. This bush

can be one of three embodiments of the bush, 30A, 30B or 30C, illustrated in

Figures 5, 6 and 7 respectively, each being more fully described below. The

bush of any of the embodiments has a unitary cylindrical body 32 made of a

steel material, which is machined pressed or cast, or moulded from plastic or

composite material.

[0018] With reference to Figures 1, 2, 5A and 5B, in describing bush 30A, the

cylindrical body extends between a first end 34 and a second end 36, and has

a central hole 38 which opens at each of these ends. The body has a pair of

spaced apart annular ridges (respectively designated 40A and 40B) projecting

from an outer cylindrical surface 42. Between the ridges, a circumferential grout

distributing channel 44 is defined. Within the channel, the body 32 has an aperture 46 which is formed through a wall of the body, fluidly communicating the channel to the central hole 38.

[0019] Each annular ridge 40, in this non-limiting example, is adapted with a

machined annular groove into which a respective O-ring seal 48 fits.

[0020] To engage the bush 30A to the rock bolt 12, the rock bolt body 14 is

passed through the bush's central hole 38, proximal end 18 leading. A trailing

portion 38.1 of the hole is circumferentially dimensioned with a small tolerance

relatively to the bolt to fit over the bolt in tight fit.

[0021] A trailing end 28 portion of the sleeve 24 inserts into a leading portion

38.2 of the central hole 38, the trailing end coming to rest on a lip or step 49

protruding into the central hole 38.

[0022] To hold the bush in position, above the threaded section 20, with the

trailing end 28 portion of the sleeve held within the central hole of the bush, a

nut 50 is threaded onto the threaded section, behind the bush. The nut will

move into contact with the trailing end 36 of the bush, forcing the bush against

the sleeve which is prevented from moving up the bolt body 14 by abutment

with the paddle 15.

[0023] Should the bolt 12 not be configured with paddles, as an alternative

fixing means, the sleeve can be crimped, swaged or welded to the bolt body.

[0024] With reference to Figure 6, 8A and 8B, a second embodiment of the

invention is described. In this embodiment, the body 14 of the bush 30B differs

from bush 30A in that the trailing portion 38.1 of the hole 38 is formed with a female thread 33 (see Figure 6). The thread provides a means by which the bush can be directly threadedly, and sealingly, engaged with the threaded section 20 of the rock bolt 12, without the need for a nut to secure the bush in place.

[0025] As with the earlier embodiment, the bush 30B is engaged fully on the

bolt body 14, between the trailing end 28 of the sleeve 24 and the proximal end

18 of the bolt. The bush is positioned flush with the proximal end of the bolt

thus providing a drive surface 35, which comprises the proximal end 18 of the

bolt and the second end 36 of the bush, which is free from obstruction. This is

particularly evident in Figure 9.

[0026] As illustrated in Figure 9, the bush need not be fixed in position by

means of the threads, but can have the trailing portion 38.1 of the hole

dimensioned to friction fit over the bolt, as with embodiment 30A, and then

welded in place along a weld line 37.

[0027] In another embodiment of invention, a bush 30C is provided which is

illustrated in Figure 7A and 7B. In this embodiment, the body 32 is not unitary,

as with the embodiment 30A, but rather is a composite body, having an inner

component 68 made of a rigid material, for example a metal (steel) material,

and an outer component 70 made of a resiliently deformable material, for

example a plastic (polyurethane) material, which shrink wraps the inner

component.

[0028] The pair of spaced apart annular ridges (40A and 40B) is integrally

moulded as part of the outer component. As this component consists of a resiliently deformable material, there is no need to provide a separate sealing element as is the case with the earlier described embodiment. The sealing function is inherent in the configuration and material of manufacture.

[0029] Each embodiment of the bush (30A, 30B and 30C) includes a formation

51, which in this example is a recessed annular formation, formed in a wall of

the leading portion 38.2 of the central hole 38. It is into this formation that the

trailing end 28 portion of the sleeve 24 is press-fitted to ensure sealing

engagement between the sleeve and the bush (see insert to Figure 8B).

[0030] A load indicating formation 52 can be included as a separate element

or made integral with the bush as illustrated, with respect to embodiment 30A,

in Figure 5B. This formation indicates when load on the barrel has reached a

predetermined level.

[0031] Completing the assembly 10, a washer or faceplate 53 is located

against the first end 34 of the bush body 32. This element is illustrated in

Figures 8A and 8B.

[0032] The assembly 10 is designed to be mechanically inserted into a pre

drilled rock hole 55 with the aid of a drill rig (not shown). The drill rig can may

have a plurality of actuator arms (not shown) on a carousel, one of which will

include a drill, adapted to drill the hole, another, an insertion arm 57, will be

adapted to aid in the insertion of the rock bolt assembly and thereafter to grout

the inserted assembly in the hole. The insertion arm has, at a leading end, a

tapered spigot (as with this example) or a threaded shaft. Alternatively the

assembly may be manually loaded onto the drill rig before being mechanically inserted into a pre-drilled hole.

[0033] To aid in the installation and grouting steps of installation process, an

adapter 54 is provided which has a tapered recess 56 into which the tapered

spigot of the insertion arm 57 inserts. The grout nozzle 11 is attached to a free

end 57 of the adapter. The grout nozzle has a cylindrical mouth 58 in a leading

end 60 of the nozzle. A plurality of grout inlet ports (respectively designated

62A and 62B) open into the mouth. In the examples illustrated there are two

ports with each port connecting to a respective supply conduit (not shown)

carrying either a first or a second adhesive component of a resin. The ports

deliver these components to the nozzle mouth.

[0034] It is anticipated that the resin components can be mixed prior to

introduction to the rock bolt assembly 10 through the bush 30. In such case

there will only be need for a single inlet port 62.

[0035] On installation, a proximal end 18 portion of the rock bolt assembly 10

carrying the bush 30B or the bush (30A, 30C) and nut 50, is received in the

mouth 58 of the nozzle. This engagement is illustrated in Figure 4 and Figure

8B. The mouth 58 is dimensioned to receive the whole of the bush in snug fit.

The seals (40 or 48) of the bush make sealing contact with an inner surface 64

of the mouth to seal the grout distributing channel 44 closed against this wall

thus providing a sealed conduit into which the adhesive components are

delivered from the respective ports 62. Figure 2 illustrates these ports opening

into the mouth which, when the bush is located therein, would be positioned

coincident with the channel.

[0036] The assembly 10 then is brought into axial alignment with the pre

drilled rock hole, with the distal end 16 of the bolt leading. Now, to force the

assembly into the hole, a force, which if required may be percussive (this

percussive action is illustrated with directional arrows on Figures 8A and 8B), is

applied by the drill rig, through insertion arm. The line of action of the force is in

a direction axial to the assembly and is imposed on either the proximal end 18

of the bolt or the drive surface 35 of the assembly (depending upon the

embodiment) by a floor 63 of the nozzle mouth 58. This percussive force

incrementally drives the assembly into the rock bolt until fully inserted, with the

faceplate 53 forced against the rock wall. The retaining element 22 holds the

assembly in this fully inserted position within the rock hole, ready for grouting.

[0037] As mentioned, the adhesive components are introduced under pump

action to the assembly via the ports 62 into the grout distributing channel 44

and, from there, through the aperture 46, into an annular space 66 between the

bush 30 and the rock bolt 12, up through the interior of the sleeve 24 and finally

into the rock hole 55. Along this course of flow, the adhesive components begin

to turbulently mix and harden or, if the components are already mixed, merely

to harden.

[0038] After grouting is completed, the arm 57 is withdrawn to remove the

nozzle 11 from engagement with the rock bolt's proximal/projecting end 18.

During the withdrawing action, the seals 48 act against the inner surface 64 of

the mouth 58 to wipe this surface of residual resinous material which, if left,

would harden and clog this part of the nozzle, not making possible imminent reuse.

[0039] The bush (30A, 30B or 30C) is a single-use item and therefore the

hardening of residual resin within the distributing channel 44 or aperture 46 is of

little consequence.

[0040] The axial force, applied to the assembly 10 at the proximal end 18 of

the rock bolt 12, is highly energetic and will damage any grout-tight seal which

is axially interposed between the bolt, the bush and the sleeve. It is for this

reason that none of the junctions in the assembly that require to be sealed (i.e.

the junction between the bush 30 and the nozzle mouth 58 or the junction

between the bush and the sleeve) are aligned in the direction of this force. In

particular, the sealed engagement of the bush with the sleeve, provided by

press-fitting the sleeve into the recessed annular formation 51 of the bush,

achieves a resilient grout-tight seal that is positioned lateral of the line of force.

Claims (7)

1. A rock bolt assembly which includes an elongate bolt which extends

between a distal end and a proximal end, a tubular sleeve which

longitudinally extends between a leading end and a trailing end, on the

bolt such that at least a proximal end portion of the bolt projects from the

trailing end of the sleeve, and a nozzle docking bush on the proximal end

portion between the trailing end of the sleeve and the proximal end of the

bolt, the bush having a cylindrical body defined between a first end and a

second end, a central hole formed through the body between the ends, a

pair of spaced apart annular ridges on an outer surface of the cylindrical

body, a grout distributing channel between the annular ridges, and an

aperture in the channel which communicates the channel with the hole,

wherein the central hole includes a leading portion which ends at the first

end and which is adapted to receive the trailing end of the sleeve in

sealing engagement, and a trailing portion which ends at the second end

and which is adapted to sealingly engage the bolt, and wherein each

annular ridge is adapted to seal against a nozzle of a grout delivery

system.

2. A rock bolt assembly according to claim 1 wherein the leading portion of

the central hole includes a formation against which the trailing end of the

sleeve is press-fitted in sealing engagement.

3. A rock bolt assembly according to claim 2 wherein the formation is an

annular ridge or an annular recess.

4. A rock bolt assembly according to anyone of claims 1 to 3 wherein the

trailing portion is formed with threads to engage complementary threads

on the proximal end portion of the bolt.

5. A rock bolt assembly according to anyone of claims 1 to 3 wherein the

trailing portion is adapted to friction fit over the proximal end portion.

6. A rock bolt assembly according to anyone of claims 1 to 5 wherein the

second end of the bush is positioned flush with the proximal end of the

bolt.

7. A rock bolt assembly according to claim 6 wherein the second end of the

bush is fixed to the proximal end of the bolt.