Rock bolt with meshing adapter

Abstract

A rock bolt and meshing assembly is arranged for installation of a meshing sheet against a surface of rock strata. The rock bolt includes an adapter having a first portion connectable to a trailing end of an elongate shaft of the rock bolt and means configured to receive and mount a meshing clamp to overlay a second section of meshing sheet against an already laid first section of meshing sheet.

Claims

1. A rock bolt for installation within a bore formed in rock strata, the rock bolt comprising: an elongate shaft having a leading end for installation into the bore and a trailing end arranged to project from an open end of the bore; a nut secured to the trailing end of the elongate shaft; and an adaptor having a connection portion, a body and a mesh clamp extending along a longitudinal axis of the bolt, the connection portion including an external facing surface and an internal thread, the internal thread being arranged to mate with an external thread of the nut so as to be connected to the nut at the trailing end of the elongate shaft, the body having an internal facing surface arranged to mate with the external facing surface of the connection portion, wherein the mesh clamp is arranged at the body or axially between an axially forwardmost part at an end of the connection portion and the body, such that the body is drivable axially on the connection portion via the engagement between the internal facing surface and the external facing surface to force the mesh clamp towards the trailing end of the elongate shaft and to bare against and urge a meshing sheet into contact with a surface of the rock strata.

2. The rock bolt as claimed in claim 1, wherein the connection portion includes an extension extending axially from said forwardmost part, wherein the mesh clamp is arranged to be mounted on the extension between said forwardmost part and the body.

3. The rock bolt as claimed in claim 2, wherein at least a region of the connection portion includes an external thread at the external facing surface and at least a region of the body includes an internal thread arranged to mate with the external thread of the connection portion such that the body is axially driveable along the connection portion via the internal and external threads.

4. The rock bolt as claimed in claim 3, wherein the external thread is provided at the extension.

5. The rock bolt as claimed in claim 3, wherein the body includes a nut head and a nut collar, the internal thread of the body being provided at the collar such that the collar is axially drivable over and along the connection portion to force the mesh clamp towards the trailing end of the elongate shaft.

6. The rock bolt according to claim 5, wherein the mesh clamp includes an opening through which a portion of the body extends axially between the nut head and the nut collar.

7. The rock bolt according to claim 6, wherein the mesh clamp has a base in which the opening is formed and arms that extend from the base to a ring configured for engagement of the meshing sheet.

8. The rock bolt according to claim 7, wherein the base is planar and extends generally perpendicular to the axis of the rock bolt.

9. The rock bolt according to claim 6, wherein the mesh clamp has a base in which the opening is formed and a skirt extends from the base, wherein the skirt has a distal end remote from the base for engagement with the meshing sheet.

10. The rock bolt according to claim 9, wherein the base is planar and extends generally perpendicular to an axis of the rock bolt.

11. The rock bolt according to claim 3, wherein the internal thread of the connection portion is formed within a socket at said forwardmost part from which the extension projects.

12. The rock bolt according to claim 11, wherein the body is a nut rotatable on the extension towards said forwardmost part to drive axially the mesh clamp towards the socket.

13. The rock bolt according to claim 2, wherein the mesh clamp includes an opening through which the extension extends.

14. The rock bolt according to claim 13, wherein the opening has an internal diameter that is greater than an external diameter of the extension so that the mesh clamp is a loose fit about the extension.

15. The rock bolt according to claim 1, wherein the body includes a first fixed connection to the connection portion, whereby installation equipment can rotate the body to rotate both the body and the adapter together for threadably connecting the adapter to the trailing end of the elongate shaft of the rock bolt.

16. The rock bolt according to claim 15, wherein the first fixed connection of the body to the connection portion includes a shear pin extending between the body and the connection portion.

17. The rock bolt according to claim 15, wherein the first fixed connection of the body to the connection portion comprises a spot weld or braze, gluing or crimping between the body and the connection portion.

18. The rock bolt according to claim 1, wherein the body is mounted to the connection portion via a friction fit and the body is movable axially along the connection portion by application of a load applied to the body which is sufficient to overcome a friction connection between the body and the connection portion.

19. A meshing assembly for installation of meshing sheet against a surface of rock strata, the meshing assembly comprising: a rock bolt as claimed in claim 1; a first section of meshing arranged to be positioned against the surface of the rock strata; a rock plate connectable to the trailing end of the rock bolt to bear against and urge the first section into contact with the surface of the rock strata; a second section of meshing arranged to be positioned against the surface of the rock strata and overlapping the first section; and a meshing clamp connectable to the connection portion and configured to bear against and urge the second section into contact with the surface of the rock strata.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) A specific implementation of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:

(2) FIG. 1 is an exploded sectional view of a wire meshing installation according to the invention;

(3) FIG. 2 is an assembled sectional view of the wire meshing installation of FIG. 1;

(4) FIG. 3 is an end view of an adapter according to the invention;

(5) FIG. 4 is a side view of an adapter according to the invention in engagement with installation equipment and wire meshing;

(6) FIG. 5 is a cross section view of a further implementation of the present adaptor and rock bolt.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION

(7) With reference to FIGS. 1 and 2, a rock bolt 10 according to the invention is illustrated and comprises a split tube 11 that extends into a bore 12 that is drilled into rock strata 13. The length of the split tube 11 can be in the order of 1 m to 3 m.

(8) The rock bolt 10 is of the kind that includes an expander mechanism within the split tube 11 towards the leading end of the tube 11. The expander mechanism is shown in simplified form at reference numeral 28 in FIG. 1. The expander mechanism comprises a wedge arrangement and one component of the wedge arrangement connects to a bar 14 that is positioned within the tube 11. In the embodiment illustrated in FIG. 1, rotation of the bar 14 within the tube 11 is operable to activate the expander mechanism to shift the wedge arrangement to expand inside the tube 11, thus tending to expand the tube 11 radially against the facing surfaces of the bore 12. This serves to cause the tube 11 to more firmly engage the surface of the bore 12, so as to firmly anchor the tube 11 within the bore 12. By this action, the rock bolt 10 provides rock strata reinforcement. An expander mechanism that operates in this manner is disclosed in Australian Patent Application No 2017901751.

(9) The trailing end of the bar 14 projects out of the bore 12 and thus forms a projecting end 15. As shown in FIG. 1, a blind nut 16 is attached to the projecting end 15 and has a closed end 17. By this arrangement, threading the blind nut 16 onto the projecting end 15 eventually brings the closed end 17 into contact with the end face of the projecting end 15, so that further rotational movement of the blind nut 16 relative to the bar 14 is prevented. That is, any further rotation of the blind nut 16 results in combined rotation of the bar 14 and the nut 16. By this mechanism, rotation of the nut 16 facilitates activation of the expander mechanism 28.

(10) Adjacent the blind nut 16 is a washer 18 and inward of the washer 18 is a ring 19. The ring 19 is welded by weld 20 to the outer surface of the tube 11 and provides a bearing surface for a rock plate 21. The rock plate 21 bears against wire meshing 25 and urges the meshing 25 into surface contact with the rock surface 26 of the rock strata 13. The rock bolt 10 is supplied with the ring 19 welded in place against the tube 11 and is installed by applying the washer 18 and the blind nut 16 to one side of the ring 19 and the rock plate 21 to the other side. The wire meshing 25 can be positioned against the rock surface 26 and the tube 11 can then be passed through the meshing 25 and driven into the bore 12 by suitable driving equipment, such as under percussion hammering by a mining Jumbo. When the tube 11 has been driven to the required depth within the bore 12, the blind nut 16 can be rotated to rotate the bar 14 and to activate the expander mechanism which is located towards the leading end of the tube 11. With these steps completed, the rock bolt 10 is installed and the meshing 25 is firmly positioned against the rock surface 26. The rock strata is thus reinforced against rock fracture and the rock surface 26 above the meshing 25 is contained against dislodgment of smaller fragments.

(11) A second section of wire meshing will be required to be installed as further sections of rock surface are exposed. It is necessary that the new section of wire meshing overlap an existing section, so that no sections of the rock face are left un-contained or un-protected. Accordingly, the same rock bolt 10 that is used to secure the wire meshing 25 in place against the rock surface 26 can be used in accordance with the present invention to secure a second section of wire meshing 27. In accordance with the invention, an adapter 30 is employed and this threads on to the blind nut 16. In that respect, FIG. 1 shows the thread 31 of the blind nut 16 that is applied to the outer hexagonal surface of the nut 16. The thread is thus made through the corners and flats of the nut 16, so that the nut 16 can be threaded onto the projecting end 15 of the bar 14 and used to drive rotation of the bar 14 to activate the expander mechanism within the split tube 11.

(12) The adapter 30 includes a thread 32 within a socket or connection portion 33 so that the adapter 30 can be threadably connected to the blind nut 16. An extension or bar 35 having an external surface 56 is coaxial with the socket portion 33 and extends from the socket portion 33. Preferably bar 35 comprises a thread 55 at external surface 56 for the connection of a nut 36 having a corresponding internal facing surface with complementary thread (not shown) mateable with the thread 55 of the bar 35. Between the socket 33 and the nut 36 is a mesh clamp 37. FIGS. 3 and 4 show the adapter 30 in end and side views respectively and it can be seen that the adapter 30 includes a base 38 and a pair of arms 39 that extend to a ring 40 and the ring 40 in use, bears against a facing surface of the meshing 27 to push the meshing 27 into the position shown in FIG. 2 in an overlapping arrangement with the existing edge of the meshing 25.

(13) The base 38 of the mesh clamp 37 includes a central opening 41 through which the bar 35 extends. It can be seen in FIG. 1, that the internal diameter of the opening 41 is greater than the external diameter of the bar 35 (including the thread that is applied to the bar 35), so that the mesh clamp 37 is a close but loose fit about the bar 35. In particular, the opening 41 is not intended to threadably connect with the bar 35. The nut 36 includes an opening 44 which accommodates a shear pin. The shear pin extends through the opening 44 and into a complementary opening 45 (see FIG. 2) in the bar 35 and with the shear pin accommodated within the respective openings 44 and 45, the nut is in fixed connection with the bar 35. In that connected state, installation equipment can engage the nut 36 and rotate it. By that rotation, each of the bar 35 and the socket 33 will also be rotated. Accordingly, by rotating the nut 36 in fixed connection to the bar 35, the socket 33 can be rotated to threadably connect with the nut 16 of the rock bolt 10. This connected arrangement is illustrated in FIG. 2.

(14) Each of FIGS. 1 and 4 show the nut 36 in engagement with installation equipment, although only the nut engagement end of the equipment is illustrated in FIG. 1. That engagement is via a suitable socket or spanner 48. FIG. 4 shows schematically, the end of a boom or arm 49 of a mining Jumbo or other suitable equipment, which carries the spanner 48 and which drives the spanner to rotate. Once the bar 35 and socket 33 have been driven to the position in which the socket 33 is in full engagement with the nut 16 of the rock bolt 10, further rotation of the nut 36 will shear the shear pin and will then allow the nut 36 to be rotated relative to the bar 35 in the normal manner of a nut, so that the nut 36 traverses along the bar 35. The nut 36 can thus move from the position shown in FIG. 1 to the advanced position shown in FIG. 2 and with that movement, the nut 36 will engage against a facing surface of the base 38 of the mesh clamp 37 and drive it forward to the position shown in FIG. 2 in which it clamps the meshing 27 in overlapping relationship with the meshing 25.

(15) Advantageously, it will be appreciated that the two separate rotation stages of the nut 36 can be performed with the spanner 48 in constant engagement with the nut 36. Thus, the spanner 48 does not need to be disengaged from the nut 36 once engagement has been made, so that both the attachment of the adapter 30 to the rock bolt 10 and the clamping of the meshing 27 by the mesh clamp 37 is all undertaken with the spanner 48 in driving connection with the nut 36. The installation of the meshing 27 via the adapter 30 is thus effectively a single stage operation.

(16) Moreover, a significate advantage provided by the present invention is that the adapter 30 can be utilised in the raising and positioning of the meshing 27 for installation of the meshing 27 in overlapping relationship with the meshing 25. FIG. 4 shows in schematic form, the adapter 30 with the socket 33 extended through an opening in the meshing 27. In that position, the socket 33 can hook the meshing 27 and when the boom 49 is lifted, the meshing 27 will also be lifted in connection with the adapter 30. Thus, with the meshing 27 being lifted by the boom 49 as shown in FIG. 4, the boom 49 can position the socket 33 for connection to the nut 16 of the rock bolt 10 still with the meshing 27 attached to the adapter 30 as shown in FIG. 4. By this arrangement, there is no need for a separate lifting and positioning of the meshing 27 in overlapping position with the meshing 25. In this arrangement, it is necessary for the outside diameter of the socket 33 to be sized sufficiently that it can fit through an opening in the meshing 27 but with those dimensions, the adapter 30 can be used to hook the meshing 27 and lift it for installation into the position shown in FIG. 2. This further enhances the single stage operation for installation of the meshing 27, as compared to the prior art, in which meshing is firstly positioned where required and thereafter, an adapter and then a meshing plate are subsequently installed.

(17) A further embodiment of the adaptor is described referring to FIG. 5. According to the further embodiment, connection portion 30 is formed as a cylindrical socket 33 having an external surface 56 comprising a thread 55 and an internal surface 57 comprising a thread 32. Thread 32 is configured for mateable engagement with thread 31 of blind nut 16 secured to the trailing end 15 of elongate shaft 14. Socket 33 further comprises an external surface 56 comprising a thread 55. Threads 55 and 32 extend substantially the full axial length of socket 33 between respective forward and rearward axial ends.

(18) According to the further embodiment, adaptor 30 further comprises body 36 comprising a nut head 50 and a nut collar 53 connected axially via a neck section 51. As described referring to the embodiment of FIGS. 1 to 4, nut head 50 is engageable by engagement apparatus 48 to drive rotation of the body 36. Mesh clamp 37 is secured over and about body 36. In particular, opening 41 is positioned around neck 51 with the arms 39 extending over and about nut collar 53 and a portion of socket 33.

(19) Nut collar 53 comprises an internal cavity defined by an internal facing surface 54. A thread 52 is provided at surface 54 for mateable engagement with thread 55 of connection portion 30. Accordingly, connection portion 30 is configured for mating onto blind nut 16 and nut collar 53 is capable of mating onto connection portion 30 via the respective threads 52, 55, 32 and 31. As described referring to FIGS. 1 to 4, a shear pin is securable through respective openings 44, 45 at nut collar 53 and connection portion 30 so as to temporarily and rotationally lock body 36 to connection portion 30 during an initial installation of the adaptor 30 onto the rock bolt 10. As described previously, further rotation of body 36 provides a shearing of the pin inserted through holes 44, 45 to provide continued rotation of body 36 axially along connection portion 30 to force meshing 27 onto the rock surface 26 to be overlapping onto the pre-installed meshing 25.

(20) The present invention is expected to provide significant time savings in the installation of meshing and that advantage has significant benefits in terms of the securing unsecured rock faces quickly and efficiently, thus reducing the likelihood of rock fracture or fall within underground mines. That is, the sooner a rock face is protected by wire meshing, the sooner the section of underground mine is rendered safe to personal and equipment operating within the mine environment.