A rock bolt assembly

Abstract

A rock bolt assembly includes an inner shaft section having an outer end and a coupler provided on the outer end. The coupler defines a socket configured to receive an inner end of another shaft section. The rock bolt assembly includes a washer provided adjacent the coupler, the washer including a central aperture dimensioned to be large enough to permit the coupler to pass therethrough and includes a locating insert which is configured to be located relative to the coupler and to abut the washer, the locating insert thus being configured to locate and hold the washer relative to the coupler, wherein the locating insert is deformable or frangible and is configured to be deformed, broken, or sheared to permit the coupler to be displaced relative to the washer through the central aperture.

Description

[0001] A Rock Bolt Assembly

[0002] FIELD OF INVENTION

[0003] This invention relates to wall bolts for use in rock walls, and it relates more specifically to a rock bolt assembly having a compound or multi-part shaft, for use in mining or construction.

[0004] BACKGROUND OF INVENTION

[0005] In mining, it is well known to install rock bolts in mine walls to provide support and stability to the walls — this is an important aspect of mine health and safety. This is common in roofs of mines to support rock and prevent rock or other debris from falling down. These rock bolts may also be known as wall anchors or rock anchors, and when installed in roofs (or hanging walls) of mines, they may be called roof bolts.

[0006] To install rock bolts, a hole is drilled into a rock wall. The depth of the hole may vary according to rock characteristics and working conditions, but may be 1-6 m deep. A wall bolt including a shaft, usually a little shorter than the depth of the hole, is inserted into the hole. The wall bolt includes an anchoring mechanism at its inner end (or dead end) which can be deployed, e.g., by rotating the shaft. An outer end (or head or live end) of the wall bolt includes a large washer (or rock plate) which engages and bears against a face of the rock wall, providing support. In other versions, the anchoring mechanism can be chemical in nature, for example resin capsules. In low ceiling mines (or low seam mines), there is little clearance (e.g., 1.0-2.0 m) between the roof and the floor. A length of the shaft of the appropriate rock bolt may in fact be longer than the distance between the roof and the floor, meaning that the wall bolt cannot effectively be fed into the hole. If a mine operator tries this, a bottom (operatively outer end) will collide with the floor and prevent the shaft from being aligned with and inserted into the hole.

[0007] Accordingly, rock bolts with compound or multi-part shafts have been developed. These rock bolts comprise plural shaft sections (e.g., two or more) which are interconnected by couplers. In use, to install these, and inner shaft section (with an anchoring mechanism) is fed into the hole. A coupler is connected to the outer end of this inner shaft section and another shaft section (an outer shaft or intermediate shaft, as the case may be) is fixedly coupled to the inner shaft section, and then both coupled shaft sections are fed further into the hole. In this fashion, shorter shaft sections constitute a longer shaft which, if of unitary construction, would not have fitted into the hole on account of the low roof.

[0008] While using multiple shaft sections may be a good practical option for getting a longer shaft into the hole, it does have challenges. Specifically, it can be a risk if the plural sections are not coupled together securely (or at all). Improper coupling of the shaft sections may defeat the purpose of the rock bolt and presents a safety risk.

[0009] This issue was described in the Applicant’s previous patent application no. PCT / IB2022 / 051454 which discloses a solution including an electrical indicator which works well in certain conditions. However, it may not work optimally in all situations, requiring insulation to separate the electrical conductor and may not function ideally where more than two shaft sections are provided.

[0010] Accordingly, the Applicant desires a rock bolt assembly having plural shaft sections configured to provide adequate coupling between the sections and to provide an indication of coupling. SUMMARY OF INVENTION

[0011] Accordingly, the invention provides a rock bolt assembly which includes: an inner shaft section having an outer end; a coupler provided on the outer end of the inner shaft section, the coupler defining a socket configured to receive an inner end of another shaft section; a washer provided adjacent the coupler, the washer including a central aperture dimensioned to be large enough to permit the coupler to pass therethrough; and a locating insert which is configured to be located relative to the coupler and to abut the washer, the locating insert thus being configured to locate and hold the washer relative to the coupler, wherein the locating insert is deformable or frangible and is configured to be deformed, broken, or sheared to permit the coupler to be displaced relative to the washer through the central aperture.

[0012] This rock bolt assembly may represent a paradigm shift from existing multi-part shaft assemblies in that it may be installed by providing, at first, the washer on the inner shaft section while shaft sections are coupled, as opposed to providing it only at the end when the shaft sections have already been coupled. This will be described further below.

[0013] The locating insert may be in the form of, or may include, a ring or annulus. The locating insert may include an attachment formation for attachment to the washer. The attachment formation may include a clip, snap-fit, or interference press-fit formation for attachment to the washer around or through the central aperture.

[0014] The locating insert may be configured to locate the coupler outwardly of the washer prior to installation. After installation, once the locating insert has been deformed or broken and the coupler has passed through the central aperture of the washer, the coupler may be located inwardly of the washer. The locating insert may be of metal, plastic, a composite material, etc. The locating insert may be not intended to influence the structural integrity of the rock bolt assembly.

[0015] The locating insert may be configured to deform or break at a load lower, even significantly lower, than that at which the rock bolt assembly is considered to be tensioned or pretensioned. For example, the locating insert may be configured to deform or break at a load of 20-100 kg. This is well below the tensioning load of rock bolts in general which is in the order of tons.

[0016] In one embodiment, the locating insert may be a destructible or sacrificial component. After being deformed or broken, it may be discarded or lost.

[0017] In another embodiment, the locating insert may function also as an indicator to indicate that coupling between adjacent shafts sections has occurred (or at least the plural shaft sections have been used). In such case, the locating insert may not be an entirely destructible or sacrificial component. The locating insert may be configured to provide a visual indication once the roof bolt assembly is installed. The locating element may be a bright or noticeable colour, or have a uniquely identifiable shape, readily identifiable by electrophotographic or similar detection equipment.

[0018] The locating insert may be configured to deform or break such that it shears. The locating insert may comprise a shoulder portion and a collar portion. The shoulder and collar portions may be configured to be sheered apart. The shoulder portion may be urged inwardly by the coupler and the collar portion may be urged outwardly by the washer. The collar portion may remain adjacent to, and outwardly of, the washer after installation, to provide a visual indication. A portion of the locating insert may be configured to abut an end of the coupler. The locating insert may include a bearing surface on an operatively outer face thereof configured to bear against an operatively inner end of the coupler.

[0019] The rock bolt assembly may include a locating formation on either or both of the inner shaft section and / or the coupler. The locating formation may be in the form of a nib, paddle, ridge, or other protuberance (or a plurality thereof) formed on the inner shaft section inwardly of the outer end. The locating formation may be in the form of a ferrule, collar, lug, or similar formation fastened (e.g., crimped) to the inner shaft section inwardly of the outer end. The locating formation may be in the form of a coating or sleeve provided on or around the inner shaft section inwardly of the outer end. The locating formation may be in the form of nibs or grooves provided on an outer surface of the coupler. The locating formation may be an inner end of the coupler against which the locating insert bears.

[0020] In a different embodiment, the locating formation may be formed integrally with the coupler. The locating formation may then be configured to break or shear off from the coupler.

[0021] The inner shaft section itself may be similar or identical to prior art inner shaft sections. The rock bolt assembly may include one or more anchoring mechanisms (e.g., prior art anchoring mechanisms) provided on, or integrated with, the inner shaft section.

[0022] The term “deformable” includes resiliently or elastically deformable, so that the locating insert can be displaced from the coupler and then remain intact, and may even remain the same shape.

[0023] The rock bolt assembly may include an outer shaft section. The rock bolt assembly may include only two shaft sections, namely the inner shaft section and the outer shaft section. The outer shaft section may then be connectable to the socket defined by the coupler. The outer shaft section may include a nut at an outer end (free end) thereof. The nut may have a diameter or footprint larger than the central aperture defined by the washer, such that the nut can engage the washer and not pass through the central aperture.

[0024] A remaining portion (if present) of the locating insert may be sandwiched between the washer and the nut.

[0025] The rock bolt assembly may include three or more shaft sections. Practically, such compound shafts seldom include more than three sections, but a rock bolt assembly comprising more than three shaft sections is not excluded from the present invention.

[0026] In such case, the rock bolt assembly may include the inner shaft section, at least one intermediate shaft section, and the outer shaft section. The intermediate shaft section may include a coupler (referred to as the intermediate coupler) at its outer end, similar or identical to the coupler (referred to as the inner coupler) of the inner shaft section. The intermediate coupler may also define a socket configured to receive an inner end of another shaft section (e.g., another intermediate shaft section or the outer shaft section).

[0027] The intermediate shaft section may include a locating insert (referred to as the intermediate locating insert) which is configured to be located relative to the intermediate coupler. However, in contrast with the inner shaft section, the intermediate shaft section may lack its own washer. The intermediate locating insert may also be deformable or frangible and configured to be deformed or broken to permit the intermediate coupler to be displaced relative to the washer of the inner shaft section through the central aperture. It will be noted that two (or more) couplers may then pass through the washer, namely the inner coupler and the (at least one) intermediate coupler. Thus, each of the inner and intermediate locating inserts may break or deform to permit through-passage of their associated couplers.

[0028] The inner and intermediate locating inserts may both function as visual indicators. In such case, the rock bolt assembly may have two (or more) indicators to indicate proper installation.

[0029] The invention extends to a rock bolt kit configured for assembling the rock bolt assembly as defined above, the kit including: the inner shaft section with the coupler connected or connectable to the outer end thereof; the washer located or locatable relative to the coupler by means of the locating insert; and the outer shaft section.

[0030] The kit may comprise a plurality of inner and outer shaft sections. The kit may comprise one or more intermediate shaft sections.

[0031] The invention extends to a rock bolt installation including at least one rock bolt assembly as defined above. Where the locating insert provides an indication function, the rock bolt installation may include a remaining portion of the locating insert sandwiched between the nut and the washer. The rock bolt installation may include at least one imaging device (e.g., a camera) to capture images or visually inspect the rock bolt assembly to observe visually the locating insert. This may indicate acceptable or unacceptable installation of the rock bolt assembly.

[0032] The invention extends to a method of installing a rock bolt assembly, the method including: providing an inner shaft section in a hole in a rock wall, wherein a coupler is engaged with an outer end of the inner shaft section, the coupler defining a socket configured to receive an inner end of another shaft section; providing a washer adjacent the coupler, the washer including a central aperture dimensioned to be large enough to permit the coupler to pass therethrough; providing a locating insert which is configured to be located relative to the coupler and to abut the washer, the locating insert thus being configured to locate and hold the washer relative to the coupler, wherein the locating insert is deformable or frangible; coupling another shaft section to the coupler; and urging the coupler inwardly thereby to deform or break the locating insert and to displace the coupler through the central aperture, such that the coupler, inner shaft section and other shaft section are displaced inwardly into the hole.

[0033] The method may include using only two shaft sections to constitute a shaft and the other shaft section may be an outer shaft section.

[0034] The method may include using three or more shaft sections; the other shaft section may therefore be an intermediate shaft section. The method may then include: providing an intermediate coupler and an intermediate locating insert on the intermediate shaft section; coupling an outer shaft section to the intermediate shaft section; and urging the intermediate coupler inwardly thereby to deform or break the intermediate locating insert and to displace the intermediate coupler through the central aperture of the washer, such that the couplers and the shaft sections are displaced inwardly into the hole. BRIEF DESCRIPTION OF DRAWINGS

[0035] The invention will now be further described, by way of example, with reference to the accompanying diagrammatic drawings.

[0036] In the drawings:

[0037] FIG. 1 shows a partial sectional side view of a rock bolt assembly in accordance with the invention;

[0038] FIG. 2 shows an enlarged axial sectional view of a portion of the rock bolt assembly of FIG. 1 ;

[0039] FIG. 3 shows a three-dimensional view of a locating insert of the rock bolt assembly of FIG. 1 ;

[0040] FIG. 4 shows a side view of the locating insert of FIG. 3;

[0041] FIG. 5 shows a partial sectional three-dimensional view of the rock bolt assembly of FIG. 1 ;

[0042] FIG. 6 shows a partial sectional three-dimensional view from another angle of the rock bolt assembly of FIG. 1 ;

[0043] FIG. 7 shows a partial sectional side view of the rock bolt assembly of FIG. 1 including an outer shaft section partially installed;

[0044] FIG. 8 shows a partial sectional side view of the rock bolt assembly of FIG. 7 fully installed;

[0045] FIG. 9 shows an enlarged axial sectional view of a portion of the rock bolt assembly of FIG. 8;

[0046] FIG. 10 shows a partial sectional three-dimensional view of the rock bolt assembly of FIG. 8;

[0047] FIG. 11 shows a side view of a second embodiment of a rock bolt assembly, in accordance with the invention;

[0048] FIG. 12 shows an enlarged view of the rock bolt assembly of FIG. 11 ; FIG. 13 shows a side view of a third embodiment of a rock bolt assembly, in accordance with the invention;

[0049] FIG. 14 shows an enlarged view of the rock bolt assembly of FIG. 13;

[0050] FIG. 15 shows a progressive composite side view of a fourth embodiment of a rock bolt assembly, in accordance with the invention;

[0051] FIG. 16 shows a progressive composite side view of a fifth embodiment of a rock bolt assembly, in accordance with the invention;

[0052] FIG. 17 shows a schematic view of a rock bolt installation including the rock bolt assembly of FIG. 12; and

[0053] FIG. 18 shows a schematic view of a rock bolt installation including the rock bolt assembly of FIG. 14.

[0054] DETAILED DESCRIPTION OF EXAMPLE EMBODIMENT

[0055] Referring to FIGS 1-10, reference numeral 100 indicates a first embodiment of a rock bolt assembly in accordance with the invention. By way of context, the rock bolt assembly 100 is intended to me mounted to a hole 12 in a mine wall or rock wall 10. This mine wall 10 may be a low-hanging ceiling, thus requiring a multi-part shaft, as described in the BACKGROUND.

[0056] The rock bolt assembly 100 has an inner shaft section 102 which is intended to be inserted into the hole 12 first (and thus will be the innermost section). The inner shaft section 102 may resemble prior art shaft sections and may have an anchoring mechanism, e.g., mechanical or chemical (not illustrated), at its inner end. The inner shaft section 102 has an outer end 104 with a threaded portion.

[0057] This outer end 104 is configured to engage a coupler 110 which forms part of the rock bolt assembly 100. The coupler 110 is cylindrical and has two oppositely-directed threaded sockets; an inwardly directed socket to engage the inner shaft section 102 and an outwardly directed socket 112 to engage another shaft section (refer to FIGS 7-10). In fact, the coupler 1 10 may merely be hollow and tubular, with the sockets simply being the opposite open ends of the coupler 110. The coupler 1 10 may resemble prior art couplers.

[0058] A notable feature of the present invention is the provision of a locating insert 120 in the rock bolt assembly 100. There may be various different forms that the insert 120 may take, and FIGS 1-10 illustrate a first embodiment of the insert 120. Another notable feature of the invention is that a washer 130 is provided on the inner shaft section 102 (at least, initially). This is unusual because in prior art installations, the washer is only provided at the outer end of the outer shaft section after the various shaft sections have been connected and installed.

[0059] The locating insert 120 (individually illustrated in FIGS 3-4) is located relative to the coupler 1 10 and abuts the washer 130. More specifically, the locating insert 120 comprises a clip 122 arranged around an aperture 123, a collar portion 124, and a shoulder portion 126. The shoulder portion 126 is merely a bearing surface provided around the aperture 123 on a side opposite to the clip 122.

[0060] The washer 130 defines a central aperture 132 which is sufficiently large to permit the coupler 1 10 to pass therethrough. Other features of the washer 130 may resemble those of prior art washers (at least, in appearance, though not in positioning). For example, the washer 130 may be a domed, ribbed washer 130.

[0061] The locating insert 120, in this embodiment, is clipped to the washer 130 by means of the clip 122. The clip 122 projects inwardly through the aperture 132 and attaches the locating insert 120 to an outer side of the washer 130, with the locating insert 120 and the washer 130 being coaxial such that their respective apertures 123, 132 are aligned. The outer end 104 of the inner shaft section 102 projects through the apertures 123, 132 of the washer 130. The outer end 104 of the inner shaft section 102 is connected to the coupler 1 10, but the aperture 123 of the locating insert 120 does not permit the coupler 1 10 to pass freely therethrough. Rather, an inner end of the coupler 110 abuts the shoulder portion 126 of the locating insert 120. Accordingly, while the locating insert 120 remains intact, it locates and holds the coupler 1 10 axially outwardly of the washer 130.

[0062] In use, FIGS 5-6 illustrate a first step of how the rock bolt assembly 100 is installed. The inner shaft section 102 is inserted into the hole 12 until the washer 130 contacts and abuts against an outer face of the rock wall 10. The inner shaft 102, being connected to the coupler 1 10, cannot be pushed further under light hand pressure, as the coupler 1 10 bears against the shoulder portion 126 of the locating insert 120. The collar portion 124 is wider than the central aperture 132 of the washer 130 and thus cannot pass through.

[0063] FIG. 7 illustrates the next step and further details about the rock bolt assembly 1 10. The rock bolt assembly 100 comprises an outer shaft section 106. In this embodiment, there are only two shaft sections, 102, 106, namely the inner and outer shaft sections 102, 106. The outer shaft section 106 has a threaded inner end 107 which is screwed into the outwardly directed socket 1 12 provided by the coupler 1 10. While the inner shaft section 102 and coupler 1 10 are held in place, the outer shaft section 106 is screwed into the socket 1 12. The two shaft sections 102, 106 are thereby coupled together to form a multi-part or compound shaft.

[0064] The outer shaft section 106 has a nut 108 at its outer (or free) end which is also threaded. The nut 108 may be conventional and is sufficiently wide so as not to be able to pass through the central aperture 132 of the washer 130.

[0065] To install the rock bolt assembly 100, an installation force, as indicated by arrow 150, is applied. This installation force 150 is greater than the deformation / shearing / breaking force of the locating insert 120. In this example, the locating insert 120 is configured to shear and break into two (or more) pieces. More specifically, the collar portion 124 is configured to shear off from the remainder (comprising the clip 122 and shoulder portion 126). The installation force 150 may be applied by a tool or other means.

[0066] As the installation force 150 is applied, this urges the outer shaft section 106, and accordingly the coupler 1 10, upwardly. This causes the coupler 1 10 to apply a corresponding upward force on the shoulder portion 126 of the locating insert 120. The washer 130, being stationary, applies a reactive downward force, indicated by arrow 152, on the collar portion 124 of the locating insert 120. These opposite forces 150, 152 cause the locating insert to shear, with the collar portion 124 remaining on the outside of the hole 12 outward of the washer 130, and the remainder 122, 126 moving upwardly (although after separation, the remainder 122, 126 of the locating insert 120 is largely irrelevant).

[0067] FIGS 8-10 illustrate the rock bolt assembly 100 after installation. Almost the entire shaft comprising the inner shaft section 102 and the outer shaft section 106 has been displaced into the hole 12. The anchoring means (whatever it may be) has been deployed and the washer 130 bears against the surface of the rock wall 10 held fixedly in place by the nut 108.

[0068] However, the collar portion 124 remains outside the hole 12, sandwiched between the washer 130 and the nut 108. The collar portion 124 may be dimensioned to be wider than the nut 108 and therefore project outwardly therefrom, so that it is readily observable. Accordingly, observing the collar portion 124 means that the inner shaft section 102 and coupler 1 10 are necessarily in the hole 12. While the collar portion 124 may not provide an indication of tensioning, it does provide an indication that the compound shaft has been constructed of the correct shaft sections 102, 106.

[0069] FIGS 1 1-12 illustrate a second embodiment of a rock bolt assembly 200, in accordance with the invention. In the FIGS relating to different embodiments, similar or identical reference numerals may reference similar or identical parts. The rock bolt assembly 200 includes a locating formation 203. In general, some type of locating formation may be desirable to locate the washer 130 and / or locating insert 120 along an inner shaft section 202 prior to installation. More specifically, the locating formation may inhibit the washer 130 and / or locating insert 120 from sliding up (operatively inwardly) along the inner shaft section 202 prior to installation.

[0070] In this example, the inner shaft section 202 is similar to that of the rock bolt assembly 100, but has a coating or sleeve 203 around most of its length. This coating increases the thickness of the inner shaft section 202 and renders it thicker than the aperture of the locating insert 120, meaning that the locating insert and washer combination 120, 130 cannot slide up past the beginning of the coating 203. After installation (FIG. 12), the outward indication of the collar portion 124 is the same as for the previous rock bolt assembly 100.

[0071] FIGS 13-14 illustrate a third embodiment of a rock bolt assembly 300, in accordance with the invention. A notable difference from the preceding embodiments is that this rock bolt assembly 300 comprises three shaft sections 302, 31 1 , 306, namely an inner shaft section 302, an intermediate shaft section 31 1 , and an outer shaft section 306. The rock bolt assembly 300 therefore has two couplers, 1 10, 310, namely an inner coupler 1 10 and an outer coupler 310.

[0072] The rock bolt assembly 300 includes the washer 130; however, the rock bolt assembly 300 now has two locating inserts 120, 320, namely an inner locating insert 120 and an outer locating insert 320. The inner locating insert 120 may be the same as that of the rock bolt assembly 100. In contrast, the outer locating insert 320 does not have the washer 130 to clip onto, so is configured differently and is merely in the form of a collar (similar to the collar portion 124 of the inner locating insert 120).

[0073] Another notable difference of the rock bolt assembly 300 is the inclusion of locating formations 303, 313 in the form of crimped ferrules, namely an inner ferrule 303 and an outer ferrule 313. The inner ferrule 303 serves to locate the washer-insert combination 120, 130 and keep it axially captive between the inner ferrule 303 itself and the inner coupler 1 10. Similarly, the outer ferrule 313 serves to keep the outer locating insert 320 axially captive between the outer ferrule 313 itself and the outer coupler 310.

[0074] To install the rock bolt assembly 300, the inner shaft section 302 and the intermediate shaft section 31 1 are coupled and displaced inwardly (as with the previous rock bolt assembly 100). However, there is another step of connecting the outer shaft section 306 to the outer coupler 310 and similarly displacing the resultant multi-part shaft inwardly into the hole 12. The outer coupler 310 may shear through or break off an inner part of the outer locating insert 320.

[0075] As illustrated in FIG. 14, once the rock bolt assembly 300 has been installed, the remaining portions of both locating inserts 120, 320 will be visible, sandwiched between the nut 108 and the washer 130. This provides an external indication that a multi-part rock bolt has been installed using three shaft sections.

[0076] FIG. 15 illustrates a fourth embodiment of a rock bolt assembly 400, in accordance with the invention. It will be noted that this rock bolt assembly 400 does not have two washers 130, but FIG. 15 is merely a composite view illustrating the rock bolt assembly 400 in its pre-installed and post-installed configurations in a single view. This embodiment is very similar to the previous embodiment, except inner and intermediate shaft sections 402, 411 have paddles 403, 403, instead of ferrules, to constrain axial movement of the washer-insert combination 120, 130 and the outer locating insert 320.

[0077] FIG. 16 illustrates a fifth embodiment of a rock bolt assembly 500, in accordance with the invention. A notable difference between this rock bolt assembly 500 and the previous ones is that its locating inserts 520, 521 are fastened (initially) to the couplers 510, 516. More specifically, the inner coupler 510 includes a pair of nibs or ridges 514 between which the inner locating insert 520 (in the form of an annular collar) is seated. The locating insert 520 may be configured to be slid outwardly over the outer nib 514 without breaking, merely by being slightly deformed outwardly over the nib 514.

[0078] The outer coupler 516 could have the same configuration (with the nibs 514) as the inner coupler 510, but, in this embodiment, it is differently configured. The outer coupler 516 and the outer locating insert 521 are of unitary construction, e.g., machined from a single piece of material (with or without undercut). The construction can also be such that a press fit ring engages with a small ridge. The outer locating insert 521 is configured to be thin so that it can be completely sheared off the outer coupler 516 with application of sufficient installation force 150. The end result is similar, with the locating inserts 520, 521 (or the remainder thereof) ending up sandwiched between the nut 108 and the washer 310.

[0079] The locating inserts 120, 320, 520, 521 may be from a material or composition configured to deform or shear (or otherwise break) at a desired load, e.g., 20-100 kg. The locating inserts 120, 320, 520 may be of plastic (or other polymeric material), metal, composite, etc. The locating insert 521 integrated with the coupler 516 may be of the same material as the coupler 516 itself, e.g., steel. The different locating inserts 120, 320, 520, 521 from the different embodiments may be mixed and matched as desired.

[0080] FIGS 17-18 illustrate rock bolt installations 160, 162 each having an imaging device in the form of a camera 170 and, respectively, the rock bolt assemblies 200, 300 installed in the rock walls 10. The cameras 170 are directed towards the locating inserts 124, 320 (or, at least, the areas where such locating inserts 124, 320 are expected to be). The cameras 170 can inspect, as indicated by arrows 172, 174, the visible parts of the rock bolt installations 160, 162 to determine that the locating inserts 124, 320 are visible when they should be, to conclude that the rock bolt assemblies 200, 300 have been constituted from the correct number of shaft sections. The locating inserts 120, 320, 520, 521 may be brightly or specially coloured or shaped, or reflective. They may include markings, e.g., machine readable markings, on their exterior sides. The cameras 170 may be connected to an image recognition platform configured to recognise programmatically whether or not the locating inserts 120, 320, 520, 521 are correctly visible. The cameras 170 may be fixed or portable, configurable to pan and tilts, etc.

[0081] The Applicant believes that the invention as exemplified is advantageous in that it provides increased safety and confidence of properly installed wall bolts that have been coupled from plural sections. The locating inserts are mechanical in nature which is robust, and can be materially designed to be repeatable by means of the input material to be aligned to the requirements of the user.

Claims

CLAIMSWhat is claimed is:

1. A rock bolt assembly (100; 200; 300; 400; 500) which includes: an inner shaft section (102; 202; 302; 402; 502) having an outer end (104); a coupler (1 10; 510) provided on the outer end of the inner shaft section, the coupler defining a socket (1 12) configured to receive an inner end of another shaft section; a washer (130) provided adjacent the coupler, the washer including a central aperture (132) dimensioned to be large enough to permit the coupler to pass therethrough; and a locating insert (120; 520) which is configured to be located relative to the coupler and to abut the washer, the locating insert thus being configured to locate and hold the washer relative to the coupler, wherein the locating insert is deformable or frangible and is configured to be deformed, broken, or sheared to permit the coupler to be displaced relative to the washer through the central aperture.

2. The rock bolt assembly as claimed in claim 1 , in which the locating insert is configured to provide an indication that at least plural shaft sections have been used.

3. The rock bolt assembly as claimed in claim 2, in which the locating insert, or a portion thereof (124), is configured to be sandwiched between the washer and a nut (108) provided outwardly of the washer after installation of the rock bolt assembly thereby to provide the indication.

4. The rock bolt assembly as claimed in any one of claims 2-3, in which the locating insert is in the form of, or includes, a ring or annulus (124; 520).

5. The rock bolt assembly (100; 200; 300; 400) as claimed in any one of claims 2- 4, in which the locating insert includes an attachment formation (122) for attachment to the washer.

6. The rock bolt assembly as claimed in claim 5, in which the attachment formation includes a clip (122), snap-fit, or interference press-fit formation for attachment to the washer around or through the central aperture.

7. The rock bolt assembly as claimed in any one of claims 2-6, in which the locating insert is configured to locate the coupler outwardly of the washer prior to installation and, after installation, once the locating insert has been deformed, sheared, or broken and the coupler has passed through the central aperture of the washer, the coupler is located inwardly of the washer.

8. The rock bolt assembly as claimed in any one of claims 2-7, in which the locating insert is configured to deform, shear, or break at a load lower than that at which the rock bolt assembly is tensioned or pretensioned.

9. The rock bolt assembly (100; 200; 300; 400) as claimed in any one of claims 2- 8, in which the locating insert includes a shoulder portion (126) and a collar portion (124).

10. The rock bolt assembly as claimed in claim 9, in which the shoulder and collar portions are configured to be sheered apart, wherein, in use, the shoulder portion is urged inwardly by the coupler and the collar portion is urged outwardly by the washer.

11. The rock bolt assembly as claimed in any one of claims 2-10, which includes a locating formation (203; 303; 403; 514) on either or both of the inner shaft section and / or the coupler.

12. The rock bolt assembly as claimed in claim 11 , in which the locating formation is in the form of one or more of: a nib, paddle (413), ridge, or other protuberance (or a plurality thereof) formed on the inner shaft section inwardly of the outer end; a ferrule (303), collar, lug, or similar formation fastened to the inner shaft section inwardly of the outer end; a coating or sleeve (203) provided on or around the inner shaft section inwardly of the outer end; nibs or grooves (514) provided on an outer surface of the coupler; and / or an inner end of the coupler against which the locating insert bears.

13. The rock bolt assembly (500) as claimed in any one of claims 2-4, in which the locating formation is formed integrally with the coupler (516) and is configured to break or shear off from the coupler.

14. The rock bolt assembly (100; 200) as claimed in any one of claims 2-13, which includes only two shaft sections (102, 106), namely the inner shaft section and an outer shaft section (106), wherein: the outer shaft section is connectable to the socket defined by the coupler; the outer shaft section includes a nut (108) at an outer end thereof; the nut has a diameter or footprint larger than the central aperture defined by the washer, such that the nut can engage the washer and not pass through the central aperture.

15. The rock bolt assembly (300; 400; 500) as claimed in any one of claims 2-13, which includes three or more shaft sections (302, 31 1 , 306; 402, 411 , 306; 502, 51 1 , 306), namely the inner shaft section (302; 402; 502), at least one intermediate shaft section (31 1 ; 411 ; 51 1 ), and an outer shaft section (306), wherein: the intermediate shaft section includes an intermediate coupler (310; 516) at its outer end, similar or identical to the coupler (referred to as the inner coupler) of the inner shaft section; the intermediate coupler defines a socket configured to receive an inner end of the outer shaft section; the intermediate shaft section includes a locating insert (referred to as the intermediate locating insert (320; 521 )) which is configured to be located relative to the intermediate coupler, the intermediate locating insert also being configured to deform, shear, or break to permit the intermediate coupler to be displaced relative to the washer of the inner shaft section through the central aperture.

16. The rock bolt assembly as claimed in claim 15, in which the inner and intermediate locating inserts both function as visual indicators, the rock bolt assembly therefore having two or more indicators to indicate proper installation of three or more shaft sections.

17. A rock bolt installation including at least one rock bolt assembly as claimed in any one of claims 2-16 installed in a rock wall (10), the rock bolt installation including the locating insert or a portion thereof sandwiched between the washer and a nut provided outwardly of the washer.

18. The rock bolt installation (160; 162) as claimed in claim 17, which includes at least one imaging device (170) configured to capture images or visually inspect the rock bolt assembly to observe visually the locating insert.

19. A method of installing a rock bolt assembly, the method including: providing an inner shaft section in a hole (12) in a rock wall, wherein a coupler is engaged with an outer end of the inner shaft section, the coupler defining a socket configured to receive an inner end of another shaft section; providing a washer adjacent the coupler, the washer including a central aperture dimensioned to be large enough to permit the coupler to pass therethrough; providing a locating insert which is configured to be located relative to the coupler and to abut the washer, the locating insert thus being configured to locate and hold the washer relative to the coupler, wherein the locating insert is deformable or frangible; coupling another shaft section to the coupler; and urging the coupler inwardly thereby to deform or break the locating insert and to displace the coupler through the central aperture, such that the coupler, inner shaft section and other shaft section are displaced inwardly into the hole and the locating insert, or a portion thereof, is sandwiched between the washer and a nut provided outwardly of the washer.

20. The method as claimed in claim 19, which includes capturing (172; 174), by an imaging device, an image of the installed rock bolt assembly to observe the locating insert, or a portion thereof, that is sandwiched between the washer and the nut.

Images