AU2020100343A4 - Nut and mesh plate - Google Patents

Abstract

A combination of a plate (10) and a nut (12) is disclosed. The plate (10) includes a central generally convex portion (16) defining a central aperture (18) having a first diameter and a peripheral, generally planar, perimeter flange (20)extending around the central portion (16). The nut (16) defines an internally threaded bore and an external drive portion (22) having a second diameter which is greater than the first diameter and an integral generally cylindrical shaft portion (24) having a third diameter which is smaller than the first and second diameters. The generally cylindrical portion (24) is located in the central aperture and retaining means (30) are provided to retain the cylindrical portion in the central aperture, while allowing the nut to rotate relative to the plate. The combination may be used to secure mesh to pre-installed rock bolts in a rock face in a mine. Advantageously, during attachment of the nut and plate to the rock bolt, over the mesh, the nut (12) may spin/rotate relative to the plate (10), as the nut is not fixed to the plate by welding or swaging, or the like. Fig 3 1/1 12 22 16 20 1032 30 FIG. 1 FIG. 2 FIG.3 2 FIG. 4

Description

1/1 12

22 16

1032 30 FIG. 1 FIG. 2

FIG.3 2

FIG. 4

"Nut and mesh plate"

Technical Field

[0001] This invention relates to a nut and plate for pinning mesh onto ground supports such as rock bolts.

Background

[0002] Rock bolts are used in rock reinforcement for the purpose of stabilising the rock mass or strata. In underground mining, they are used for supporting one or more of the development faces of an underground mine. As underground mining depths and stresses increase, seismically active mines, mining methods and poor ground conditions are increasingly causing rock falls and rockbursts in mine development faces. These challenges have provided a need to use steel mesh to support the face at many mining operations, to protect personnel working underground.

[0003] This steel mesh is traditionally installed during the bolting cycle using plates which contact the mesh and include a drive portion allowing the plate to be spun onto the rock bolt to push/compress the mesh against the rock face. The mesh provides passive confinement, particularly in poor ground conditions, preventing fragments of rock, coal or the like from falling from the development faces in between the reinforcing rock bolts.

[0004] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.

Summary

[0005] According to a first broad aspect of the present invention, there is provided a combination of a plate having a central generally convex or domed portion defining a central aperture and a peripheral, generally planar, perimeter extending around the central portion and an internally threaded nut connected to the plate in a manner which allows the nut to rotate relative to the plate, the combination being for use in attaching the plate to a ground support in a mine tunnel or the like, such as a rock bolt or the like, for installing a mesh over the ground support.

[0006] Advantageously, during attachment of the nut and plate to the ground support, over the mesh, the combination allows the nut to spin/rotate relative to the plate, as the nut is not permanently affixed to the plate.

[0007] The aperture is preferably located at the top of the domed portion and is smaller than the diameter of the nut. The nut may define a depending cylindrical shaft that is smaller than the diameter of the aperture which locates in the aperture of the plate. The nut shaft and hole preferably have sufficient clearance to allow the nut to spin freely when seated on top of the plate.

[0008] The bottom of the nut has a recess to receive a circlip or similar clip for retaining the nut. The circlip is larger than the diameter of the aperture so that the nut and plate remain connected together when the circlip is in place.

[0009] Thus in one preferred embodiment the invention provides a combination of a plate and a nut, wherein:

the plate includes a central generally convex or domed portion defining a central aperture having a first diameter and a peripheral, generally planar, perimeter flange extending around the central portion; and wherein the nut defines an internally threaded bore and an external drive portion having a second diameter which is greater than the first diameter and an integral generally cylindrical shaft portion having a third diameter which is smaller than the first and second diameters diameter and wherein the generally cylindrical portion of the nut is located in the central aperture and retaining means are provided to retain the cylindrical portion in the central aperture, while allowing the nut to rotate relative to the plate.

[0010] Ina related aspect, there is provided a method of attaching a mesh onto a rock face over ground supports such as rock bolts using a combination as according to the first aspect and embodiments, comprising the steps of

placing a mesh over a one or more rock bolts installed in and projecting from the rock face;

placing the plate and nut combination over the rock bolt, and threading the nut onto an externally threaded portion of the rock bolt;

applying torque to the nut to drive it onto the rock bolt and to press the plate onto the mesh retaining the mesh against the rock face while allowing the nut to spin relative to the plate during the application of the torque to the nut.

[0011] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

Brief Description of Drawings

[0012] Specific embodiments of the present invention will now be described, byway of example only, and with reference to the accompanying drawings, in which:

Figure 1 is a perspective view from above and one side of a combination of nut and domed plate embodying the invention;

Figure 2 is a view of the combination shown in Figure 1 from below;

Figure 3 is a section through the nut and plate; and

Figure 4 is a side view showing the combination threaded onto a rock bolt.

Description of Embodiments

[0013] Referring to the drawings, Figures Ito 4 show a combination of a domed plate and an associated nut 12, for attaching the plate over a rock bolt 14 (refer to Figure 4). The plate includes a curved or convex central portion 16 which defines a central aperture 18 and an integrally formed, substantially planar, annular perimeter or flange 20.

[0014] The nut 12 defines a hexagonal drive portion 22 for engagement with a drive head (not shown) of a bolting machine or the like. The effective diameter of the hexagonal drive portion 22 is larger than the diameter of the aperture 18 in the plate. A relatively short cylindrical shaft portion 24 is integrally formed with the drive portion and depends from the hexagonal drive portion. The external diameter of the short cylindrical portion 24 is smaller than the diameter of the aperture 18 so that can pass through the aperture 18, although the larger diameter drive portion 22 is unable to pass the aperture, as it is too wide. The clearance between the external diameter of the cylindrical portion 24 and the diameter of the aperture 18 is such that the nut and plate can spin freely relative to one another. Towards the end of the cylindrical portion of the nut, distal from the drive portion, there is a groove 26 which extends around the exterior of the cylindrical portion 24. The groove is typically formed by machining.

[0015] As is best seen in Figure 3, a circlip 30 or other suitable fastener or retention means, is inserted in the groove 26. The external diameter 32 of the circlip 30 is larger than the diameter of the aperture 18 and thus the circlip prevents the nut from disengaging from the plate.

[0016] During use of the nut and plate combination to install mesh, sheets of mine mesh are located over previously installed rock bolts 14. The nut 10 and plate 12 are placed on the threaded end of a previously installed rock bolt 14. The nut is not fixed to the plate and thus may continue to spin freely even after the plate 12 has engaged with the mine mesh. Friction between the plate and the mine mesh inhibits rotation of the plate which tends to remain stationary as the nut tightens onto the rock bolt and pushes the mesh onto the rockface.

[0017] Allowing the plate to spin relative to the nut reduces friction during installation, compared to combinations where the plate is welded or otherwise fixed to the nut and allows increased torque to be applied to the nut, as well as helping to prevent the plate getting jammed in the mesh which would inhibit spinning of the nut and tensioning up.

[0018] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims (8)

CLAIMS:

1. A combination of a plate and a nut, wherein:

the plate includes a central generally convex or domed portion defining a central aperture having a first diameter and a peripheral, generally planar, perimeter flange extending around the central portion; and wherein

the nut defines an internally threaded bore and an external drive portion having a second diameter which is greater than the first diameter and an integral generally cylindrical shaft portion having a third diameter which is smaller than the first and second diameters and wherein

the generally cylindrical portion of the nut is located in the central aperture and retaining means are provided to retain the cylindrical portion in the central aperture, while allowing the nut to rotate relative to the plate.

2. The combination of claim 1 wherein the cylindrical shaft defines a recess extending around the perimeter of the shaft for receiving a circlip..

3. The combination of claim 2 including a circlip installed in the recess and wherein the external diameter of the circlip is larger than the first diameter such that the nut and plate remain connected together.

4. A combination of a plate having a central generally convex portion defining a central aperture and a peripheral, generally planar, perimeter flange extending around the central portion and an internally threaded nut connected to the plate in a manner which allows the nut to rotate relative to the plate, the combination being for use in attaching the plate to a ground support in a mine tunnel or the like, such as a rock bolt or the like, for installing a mesh over the ground support.

5. The combination of claim 1 wherein the aperture is located at the top of the domed potion and is smaller than the diameter of the nut and wherein the nut defines a depending cylindrical shaft that is smaller than the diameter of the aperture, the cylindrical shaft locating in the aperture of the plate.

6. The combination of claim 2 wherein the cylindrical shaft defines a recess for receiving a circlip or similar clip for retaining the nut.

7. The combination of claim 3 including a circlip installed in the recess and wherein the diameter of the circlip is larger than the diameter of the aperture so that the nut and plate remain connected together.

8. A method of attaching a mesh onto a rock face over ground supports such as rock bolts using a combination of a plate and nut as claimed in any one of claims 1 to 7 comprising the steps of

placing a mesh over a one or more rock bolts installed in and projecting from the rock face;

placing the plate and nut combination over the rock bolt, and threading the nut onto an externally threaded portion of the rock bolt;

applying torque to the nut to drive it onto the rock bolt and to press the plate onto the mesh which holds the mesh against the rock face while allowing the nut to spin relative to the plate during the application of the torque to the nut.