Rock bolt with information display area

Abstract

The present invention relates to a rock bolt having an information display area for installation in a hole formed in a rock formation, the rock bolt having an elongated shaft having a leading end and a trailing end, the leading end being for installation in the hole and the trailing end protruding from the open end of the hole. A locking nut can be screwed to the trailing end and the locking nut is adapted to display product information or the like on a display face. The display face is axially recessed into the nut to provide protection against damage to the display face which could otherwise render the information unreadable.

Description

[0001] This application is a divisional application of the Chinese application with application number 201980052140.4, application date August 20, 2019, and title “Rock Bolt with Information Display Area”. Technical Field

[0002] The present invention relates to a rock bolt for installation in a hole formed in a rock formation and in particular to a rock bolt having a nut with a recess for displaying information. Background Art

[0003] Roof support and wall support are critical in underground mining and tunneling operations. Tunnel walls and roofs are often made of rock formations that require reinforcement to prevent damage, breakage or collapse. Typically, reinforcement is provided by drilling holes formed in the rock formation and then installing rock bolts into the formed holes, where they are fixed to resist major rock failure and formation breakage.

[0004] Different forms of rock bolts have been developed, including resin anchors or cement grout anchors, which are frictionally fixed in the hole by using a resin or grout introduced into the hole before the anchor, wherein the resin or grout cures to lock the anchor in place. Mechanical friction rock bolts have an expander mechanism positioned towards the leading end, which is used to expand radially in the hole to prevent axial withdrawal. The tail end of resin rock bolts, grout rock bolts and mechanical friction rock bolts usually protrude a short distance out of the hole and remain visible. In some cases, the tail end of the anchor is used to support an auxiliary fixing device, such as a closed grid (via a grid plate), mining service facilities, pipelines, cables, etc. In some installations, the protruding end of the rock bolt may be threaded for connection to a mechanical fixing device.

[0005] The locking nut at the rear end of the rock bolt may be a blind nut which, in the case of a mechanical friction anchor, is configured to engage the rear end of the rod such that further rotation of the nut provides a corresponding rotation of the anchor shaft to provide installation via translational expansion of the expander mechanism. Typically, product information is stamped on the outer exposed face of the locking nut, which may include an alphanumeric code for material traceability, an anchor ID, etc. However, this outer exposed face is often damaged by the anchor installation driver tool when the anchor is hammered into the hole. As a result, such stamped information is often rendered unreadable. Summary of the invention

[0006] An object of the present invention is to provide a rock bolt configured to display information which is protected from being damaged during installation of the anchor into a receiving borehole in a rock formation so as to preserve the information that can be displayed after installation of the anchor.

[0007] A specific object is to provide a locking nut for a rock bolt, which is suitable for carrying relevant information visible to personnel in a mine tunnel (wherein the rock bolt is installed, for example in a pit wall or pit roof), such as anchor identification (ID), material traceability information, manufacturer information, rock bolt type information, codes, logos, trademarks and other markings.

[0008] The above objects are achieved by providing a rock bolt having an axially rearward nut attached to the elongated shaft of the anchor bolt and having a recessed portion which in turn provides a display surface which is axially recessed relative to the axially rearward exposed surface of the nut. Since the display surface is axially recessed (relative to the rearward exposed surface), the display surface is protected from damage by the anchor bolt driver tool, in particular from damage by a driver socket which is typically located on and around the nut to transmit the impact hammering action.

[0009] Conventionally, the anchor driver tool, in particular the driver sleeve, is at least partially tubular, having a cylindrical inner cavity. Optionally, the nut of the rock bolt of the present invention is provided with a recessed portion, the diameter of which is approximately equal to or smaller than the diameter of the cylindrical inner cavity of the driver sleeve, so that any part of the driver sleeve is positioned not to contact or extend over the recessed portion, in particular the axially recessed display surface. According to a preferred embodiment, the recessed portion and the recessed display surface are centrally located on the rearwardly facing exposed surface of the nut, and the exposed surface is annular so as to extend around the recessed portion and the display surface. In such an embodiment, the driver sleeve, in particular the abutment contact area of ​​the driver sleeve, is adapted to sit in contact with the annular exposed surface and not cover the recessed portion.

[0010] According to a first aspect of the present invention, there is provided a rock bolt for installation in a hole formed in a rock formation, the rock bolt comprising: an elongated shaft having a leading end and a threaded tail end, the leading end being used to be installed in the hole, the tail end protruding from the open end of the hole; a nut with an internal thread, the nut being attached at the tail end to install a rock plate against the surface of the rock formation, the nut having an axially forward-facing contact surface and an axially rearward-facing exposed surface, the axially forward-facing contact surface being used to be positioned opposite to the rock plate, the rock bolt being characterized in that it comprises a recessed portion extending axially inwardly from the exposed surface and defining an axially rearward-facing display surface, the display surface being axially recessed relative to the exposed surface.

[0011] Optionally, when the nut is used in a mechanical friction anchor system, the nut is optionally a blind nut or a semi-blind nut. Optionally, for example in a resin anchor or cement grout anchor system, the nut may be a non-blind nut to include an internally threaded through hole between the first axial end and the second axial end. The threads may extend all or part of the axial length of the nut.

[0012] Optionally, the exposed face is annular and the display face is centrally located on and surrounded by the exposed face. Optionally, the nut is semi-blind and the display face is annular and extends around the central opening into the internal thread cavity of the nut. Optionally, the nut may be semi-blind and include a non-circular recessed wall. If the nut is completely blind, the display face may be circular, polygonal, in particular hexagonal or heptagonal.

[0013] Optionally, the anchor bolt further comprises a lug which is mounted in the recess and has a lug display face which faces axially rearward. The lug may be disc-shaped, or at least partially disc-shaped. Optionally, the lug may be substantially planar, or may be mushroom-shaped having a forward-facing face and a rearward-facing face. The lug may include indicia disposed on each of the forward and rearward-facing faces. Thus, the lug may be positioned in two different orientations in the recess. Optionally, the lug may be non-circular (e.g., hexagonal). Optionally, the lug may be non-planar and may include a head and a shaft extending from the head. Preferably, the shaft is positionable in the opening of the semi-blind nut.

[0014] Preferably, the anchor bolt further comprises markings provided at the display surface. The markings at the display surface of the nut may be in addition to any markings provided at the display surface of the tab. Thus, the information on the display surface of the nut may be the same as or different from the information provided on the display surface of the tab.

[0015] Optionally, the outer surface of the nut comprises a polygonal, square or hexagonal cross-sectional profile.This configuration provides a nut that can be conveniently engaged and driven by a conventional anchor driving device having an engaging driver sleeve.

[0016] Preferably, the nut has threads on the outer surface. This is advantageous for attaching an auxiliary fixing device to the nut, and this auxiliary fixing device has a sleeve with an internal thread for being threaded onto the outer surface of the nut.

[0017] Optionally, the recessed portion includes an undercut so that the diameter of the recessed portion increases in the axial direction from the exposed surface. Optionally, the recessed portion may be provided with an adhesive, a crimp, a weld or at least one radial protrusion extending radially to cover at least a portion of the lug. Optionally, where the recessed portion includes an undercut, the lug may be secured in the recessed portion by abutting under the undercut. Optionally, the recessed portion may be threaded so that the lug may be screwed into the recessed portion via a suitable fork tool or other engagement tool.

[0018] Preferably, the axial thickness of the tab is less than the axial depth of the recess. In particular, the thickness of the tab is less than the minimum axial depth of the recess, wherein the depth of the recess is non-uniform at the nut. Optionally, the distance by which the visible face is axially recessed relative to the exposed face is less than the radial wall thickness of the nut. Optionally, the distance is less than the thickness of the end wall of a semi-blind nut or a fully blind nut.

[0019] Alternatively, the rock bolt may be a resin anchor, a cement grout anchor or a mechanical friction anchor or any other anchor with a nut. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Specific embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:

[0021] Figure 1 is a partial cross-sectional view of a mechanical friction rock bolt assembly according to a specific embodiment of the present invention, wherein the mechanical friction rock bolt assembly is configured to be anchored and installed in a hole formed in a rock formation;

[0022] Figure 2 is a cross-sectional perspective view of a locking nut according to the above specific embodiment of the present invention, wherein the locking nut is fixed to Figure 1 At the tail end of the rock bolt;

[0023] Figure 3 is a cross-sectional perspective view of a locking nut according to another specific embodiment of the present invention, which can be fixed to Figure 1 The tail end of the rock bolt;

[0024] Figure 4 is a cross-sectional perspective view of another embodiment of a locking nut that can be secured to Figure 1 The tail end of the rock bolt;

[0025] Figure 5 is a cross-sectional perspective view of a bolt driver sleeve positioned with Figure 4 to the locking nut to Figure 1 The rock bolt is impact driven into the drill hole. DETAILED DESCRIPTION

[0026] The locking nut of the present invention is suitable for use with various different types of rock bolts, including resin rock bolts, cement grout rock bolts and mechanical friction rock bolts, wherein the nut can be attached to the tail end of an elongated shaft of the rock bolt via cooperating threads. The locking nut according to the present invention is used with different types of rock bolts, and the locking nut of the present invention can be used to actuate an expander mechanism within a mechanical friction rock bolt, and / or to secure a rock plate or grid plate against a rock formation at an area surrounding a borehole in which the rock bolt is installed. According to all embodiments, the locking nut of the present invention is internally threaded and is suitable for releasably securing to the threaded tail end of an elongated shaft, which extends through the rock bolt.

[0027] For purposes of describing aspects of the present invention, a locking nut configured to display information is described with reference to a mechanical friction anchor. Specifically, with reference to Figure 1 The friction rock bolt assembly 10 is configured to be installed and secured within a hole 36 extending within a rock formation 15. The friction anchor 10 is generally elongated, centered about a longitudinal axis 52, and generally includes: an elongated tube 25 that is split in an axial direction; an expander mechanism, generally indicated by reference numeral 11; and an anchor mechanism, generally indicated by reference numeral 12. The expander mechanism 11 is mounted toward a leading end 16 of the tube 25, while the anchor mechanism 12 is located toward a trailing end 41 of the tube 25. In particular, the anchor mechanism 12 projects rearwardly from the tube 25, and the anchor mechanism 12 is located at and extends from an open end of the hole 36 that is adjacent to a surface 35 of the rock formation 15 surrounding the open end of the hole.

[0028] The expander mechanism 11 can be formed by a pair of cooperating wedges 14, 17. The first wedge 14 is generally formed as a collar having an inner bore having radially inwardly facing threads to engage and cooperate with corresponding threads 20 provided at a first leading end 21 of an extension rod 22, which extends axially from the tube tail end 41 through the tube 25 to the tube leading end 16. Accordingly, the first wedge 14 can be axially adjusted at the rod 22 via the corresponding threads. The second wedge 17 is rigidly mounted to the inwardly facing surface 26 of the tube 25 at a position toward the tube leading end 16. The first wedge 14 and the second wedge 17 each include corresponding engagement surfaces 18, 19 aligned transversely to the axis 52. Thus, by linearly axially adjusting the first wedge 14 along the rod 22, the engagement surface 18 of the first wedge 14 abuts the engagement surface 19 of the second wedge 17, thereby forcing the first wedge 14 radially outward from the axis 52 and against the tube inner surface 26. The radial expansion of the expander mechanism 11 acts to push the tube 25 and deform the tube 25 radially outward against the inner surface of the bore 36 to lock the friction anchor assembly 10 within the bore 36.

[0029] The linear axial movement of the first wedge 14 is provided by the anchor mechanism 12, which includes an internally threaded nut 32 mounted to the second trailing end 40 of the rod 22. Thus, rotation of the nut 32 about the axis 52 provides a corresponding rotation of the rod 22, which in turn (via the threads 20) pulls the first wedge 14 toward the tube trailing end 41 to provide a radial expansion force. The anchor mechanism 12 also includes a washer 31 (alternatively referred to as a shim) having a central hole 33 that is seated around and surrounds the rod 22 at the trailing end 40. The shim 31 is not integrally formed with the nut 32, the tube 25, and other components of the anchor assembly 10, and is thus a separate component. The shim 31 protrudes radially outward from the rod 22 and the tube 25, such that an abutment surface 37 oriented axially generally toward the tube leading end 16 extends radially outward beyond a radially outwardly facing surface 54 of the tube 25. The distance that the gasket 31 and the surface 37 extend radially outward beyond the outer surface 54 of the tube is approximately equal to or greater than the corresponding radial distance that the gasket 31 protrudes radially inward from the inner surface 26 of the tube toward the rod 22, wherein the rod 22 is centered about the axis 52. As will be appreciated, the distance that the gasket 31 extends radially beyond the tube wall can be varied and selected to suit a particular application. Thus, the gasket 31 provides a radially outwardly extending flange at the tube tail end 41 and the rod tail end 40. The gasket 31 thus protrudes radially outward beyond the diameter of the hole 36 (which is formed in the rock formation 15) so that at least the radially outer region of the abutment surface 37 can be directly or indirectly supported against the rock formation surface 35, which radially surrounds the open end of the hole.

[0030] According to the above specific embodiment, the friction rock bolt assembly 10 includes a rock plate, generally indicated at 30, formed as a generally annular gasket having a radial outer portion and a corresponding radial inner portion. The radial outer portion includes a generally annular (or otherwise rectangular) abutment surface 23 configured to seat against a formation surface 35, while the inner portion terminates with an annular edge 48 defining a central hole having a diameter slightly greater than the diameter of the tube 25, but less than the corresponding diameter of the gasket 31. In particular, the radial inner edge 48 of the rock plate 30 is configured to abut the gasket surface 37 so that the gasket 31 is supported against the formation surface 35 via the rock plate 30. Thus, the gasket 31 projects radially outward from the tube 25 to provide an appropriate radial overlap between the radially inner portion of the rock plate 30 and the radially outer portion of the gasket 31, thereby allowing the gasket 31 to be supported against the rock plate 30, which in turn is supported against the rock formation surface 35 directly or via an intermediate grid sheet (not shown) to provide containment of the rock formation at the tunnel pit wall or pit roof. The tube tail end 41 according to the above-mentioned specific embodiment does not have a ring or hoop (not shown) positioned externally at the outer surface 54 of the tube. Such a ring or hoop can be welded to the tail end 41 to provide an area of ​​abutment with the radially inner edge 48 of the rock plate 30. According to other embodiments, the gasket 31 can be configured to be seated directly against the rock formation 15 via corresponding abutment between the abutment surface 37 and the rock surface 35.

[0031] Reference Figure 2 The nut 32 includes an outer surface 42 having a polygonal and in particular hexagonal cross-sectional profile. Threads 39 are provided on the outer surface 42 to facilitate mounting of auxiliary accessories to the nut 32 before or once the anchor 10 is installed and secured in position within the hole 36. The nut 32 includes a generally cylindrical inner cavity 28 defined by a radially inwardly facing inner surface 55 on which threads 34 are formed. The threads 34 extend substantially over the entire axial length of the nut 32 between the axially forwardly facing annular contact surface 13 and a semi-blind innermost end of the cavity 28 defined by the end wall 43. An opening 50 is formed in the end wall 43. However, according to other embodiments, the end wall 43 may be solid over the entire diameter, thereby defining a completely blind nut 32. The axial rearward end of the nut 32 is defined by an axially rearwardly facing annular exposed surface 38 which represents the axial end of the nut wall 27 defining the internal cavity 28. The rearward end of the nut 32 is further defined by an end wall 43 and an opening 50.

[0032] According to the above specific embodiment, a recessed portion, generally indicated by reference numeral 45, is provided at the axial rear end of the nut 32 at the region of the end wall 43. In particular, the central region of the exposed surface 38 is recessed axially inwardly so that the display surface 29 (which represents the axially rearwardly facing surface of the end wall 43) is axially recessed relative to the exposed surface 38. The display surface 29 is annular so as to surround the circular opening 50, and the display surface 29 is in turn surrounded by the annular exposed surface 38. According to the above specific embodiment, the axial distance by which the display surface 29 is axially recessed relative to the exposed surface 38 is less than the thickness of the nut wall 27, and in particular less than 50%, 40%, 30% of the wall thickness, and the axial distance may be in the range of 5% to 30% or 5% to 20% of the thickness of the nut wall 27.

[0033] Reference Figure 4 , the recessed portion 45 may be formed with an undercut portion 49 such that the diameter of the recess increases from the exposed surface 38 toward the end wall 43 in the axial direction. Figure 2 and Figure 4 In the embodiment of the present invention, a display protrusion 47 having a disc-shaped configuration can be installed in the recessed portion 45. Figure 4 In an embodiment, the tab 47 can be secured by abutting contact under the undercut 49, which forms a securing lip around the perimeter of the tab 47. Accordingly, the tab 47 can be formed of an elastically deformable and / or flexible material such as a metal or polymer. Thus, the tab 47 is secured in place by frictional contact between the undercut 49 and the wall 43, and the tab 47 is positioned to contact and cover the display surface 29 ( Figure 2 The thickness of the protrusion 47 is less than the axial depth of the recessed portion 45 , so that the protrusion display surface 46 is coplanarly aligned with the exposed surface 38 or preferably recessed with respect to the exposed surface 38 .

[0034] The recessed display face 29 at the end wall 43 can display information related to the anchor 10, the installation area, the manufacturer of the components described herein, the installer, or other relevant information, including materials, dates, product codes, logos, trademarks, etc. In particular, the display face 29 can display indicia, which may be marked, printed, etched, embossed, or otherwise attached to the face 29. As should be appreciated, the same or similar information may be provided at the tab display face 46, and such information may be in addition to or in lieu of the information displayed on the end wall display face 29.

[0035] As reference Figure 5As described in detail, the present arrangement of the nut 32 is advantageous because damage to the display surfaces 29, 46 by an anchor driver tool, particularly a driver sleeve 51, which contacts the nut 32 to impact hammer the rock bolt 10 into the hole 36 is avoided. In particular, the driver sleeve 51 includes an annular leading end face 53, which is used to abut against the washer 31. An internal cavity 57 extends axially from the end face 53. A shoulder 60 projects radially inwardly at the axial inner end of the cavity 57 to define an annular cavity end face 56. A generally cylindrical bore 58 extends axially rearwardly from the cavity end face 56 and is defined by a radially inwardly facing surface 59. Preferably, the diameter of the recess 45, particularly the diameter of the display surface 29, is approximately equal to or less than the diameter of the driver sleeve bore 58, so that no portion of the driver sleeve 51 can abut against the display surface 29 of the wall 43 and / or the tab display surface 46. As will be appreciated, the driver sleeve 51 may vary in design and may not include the central hole 58, such that the cavity end face 56 is circular and can fully abut against the rearward facing end face of the nut 32. The driver sleeve end face 56 abuts only the exposed face 38 via the recess 45 to protect and retain the information (indicia) 44 provided on the respective display faces 29, 46.

[0036] Reference Figure 3 Another embodiment of the present invention is described in which the nut 32 is not a blind nut or a semi-blind nut and ( Figure 2 The inner cavity 28 of the nut 32 extends the entire axial length of the nut 32 between the contact surface 13 and the axial last exposed surface 38. According to this other embodiment, the recess 45 is annular and is recessed into the exposed surface 38 in the form of an annular channel or groove so as to divide the exposed surface 38 into an annular inner surface 38b and an annular outer surface 38a in the radial direction. Figure 2 What is described is that information 44 is provided at the display surface 29 (in Figure 3 In addition, refer to Figure 4 The annular tab 46 of the type described may be obtained by referring to Figure 4 The optional anchoring mechanism described in the embodiments of the present invention is mounted in the annular recess 45. It should be understood that an important aspect of all embodiments of the present invention is that the display face 29 is axially recessed relative to the axially last exposed face 38, 38a, 38b to avoid damaging abutting contact with the driver sleeve end face 56. This recessed arrangement structure can also protect and preserve the displayed information from damage due to the attachment of auxiliary fixing devices (such as rock panels, mining service facilities, pipelines, cables, eyelets, grid plate accessories, etc.).

Claims

1. A rock bolt (10) for installation in a hole (36) formed in a rock formation (15), the rock bolt comprising: an elongated shaft (22) having a leading end for mounting in the hole (36) and a threaded trailing end (40) for protruding from an open end of the hole (36); an internally threaded nut (32) attached to the rear end (40) to mount the rock plate (30) against the surface (35) of the rock formation (15), the nut (32) having an axially forward facing contact surface (13) and an axially rearward facing exposed surface (38), the axially forward facing contact surface (13) being used to be positioned relative to the rock plate (30); a recessed portion (45) extending axially inwardly from the exposed surface (38), the recessed portion defining an axially rearwardly facing display surface (29), the axially rearwardly facing display surface (29) being axially recessed relative to the exposed surface (38), wherein the exposed surface (38) is annular, and the display surface (29) is centrally located and surrounded by the exposed surface (38), The invention is characterized in that the rock bolt further comprises a mark (44) arranged on the display surface (29).

2. The rock bolt according to claim 1, wherein: The nut (32) is a blind nut or a semi-blind nut.

3. The rock bolt according to claim 2, wherein: The nut (32) is semi-blind, and the display surface (29) is annular and extends around a central opening (50) into the internal threaded cavity (28) of the nut (32).

4. The rock bolt according to any one of the preceding claims, further comprising a tab (47) mounted in the recess (45) and having a tab display surface (46).

5. The rock bolt according to claim 4, wherein the mark (44) is provided at the tab display surface (46).

6. The rock bolt according to any one of claims 1 to 3, wherein: The outer surface (42) of the nut (32) includes a polygonal cross-sectional profile.

7. The rock bolt according to claim 6, wherein: The nut (32) includes threads (39) at the outer surface (42).

8. The rock bolt according to claim 4, wherein: The recessed portion (45) includes an undercut portion (49) such that a diameter of the recessed portion (45) increases from the exposed surface (38) in an axial direction.

9. The rock bolt according to claim 8, wherein: The protruding piece (47) is fixed in the recessed portion (45) by abutting below the undercut portion (49).

10. The rock bolt according to claim 4, wherein: The axial thickness of the protruding piece (47) is smaller than the axial depth of the recessed portion (45).

11. The rock bolt according to claim 4, wherein: The protrusion (47) is fixed in the recess (45) by adhesive, crimping, welding or at least one radial protrusion, and the at least one radial protrusion extends in the radial direction to cover at least a portion of the protrusion (47).

12. The rock bolt according to any one of claims 1 to 3, wherein: The distance by which the display surface (29) is recessed in the axial direction relative to the exposed surface (38) is smaller than the radial wall thickness of the nut (32).

13. The rock bolt according to claim 12, wherein: The distance that the display surface (29) is recessed in the axial direction relative to the exposed surface (38) is less than half of the radial wall thickness of the nut (32).

14. The rock bolt according to any one of claims 1 to 3, wherein the rock bolt is a resin anchor bolt, a cement grouting anchor bolt or a mechanical friction anchor bolt.

15. The rock bolt according to claim 6, wherein: The outer surface (42) of the nut (32) includes a square or hexagonal cross-sectional profile.

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