AU773970B2

AU773970B2 - An anchor bolt assembly

Info

Publication number: AU773970B2
Application number: AU14093/01A
Authority: AU
Inventors: Arie Cornelis Dekker
Original assignee: RSC Mining Pty Ltd; RSC Mining Ltd Pty
Current assignee: RSC Mining Pty Ltd
Priority date: 1999-12-15
Filing date: 2000-12-04
Publication date: 2004-06-10
Anticipated expiration: 2020-12-04
Also published as: GB2362443A; GB2362443B; WO2001044621A1; CA2363986A1; AU1409301A; GB0118818D0

Description

AN ANCHOR BOLT ASSEMBLY This invention relates to an anchor assembly. It also relates to an anchor bolt for use with an anchor assembly and to an elongate bar.

For the purposes of this specification, the application of the invention in mining operations should be predominately, but not exclusively, borne in mind.

Accordingly, the anchor assembly may be used as a rock anchor e.g. a roof bolt or the like.

In the specification the term "comprising" shall be understood to have a broad meaning similar to the term "including" and will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. This definition also applies to variations on the term "comprising" such as "comprise" and "comprises".

According to the invention there is provided an anchor bolt assembly which includes an elongate anchor element including a threaded portion and a ribbed portion, the ribbed portion including an elongate cylindrical core on which a plurality of spaced ribs are provided, at least two adjacent ribs being of different height; and a bearing arrangement which includes a screw-threaded nut which is received on the threaded portion of the anchor element.

fee- 25 Typically, the assembly includes a dome washer with a dogear.

0* S l 0e Further in accordance with the invention, there is provided an anchor bolt including an elongate anchor element, which includes a threaded portion and a ribbed portion, the ribbed portion including an elongate cylindrical core on which a plurality of spaced ribs are provided, at least two adjacent ribs being of different height relative to the core.

WO 01/44621 pCT/IB00/01789 2 In certain embodiments, the ribs are curved in a serpentine fashion relative to a peripheral surface of the core thereby to enhance mixing of grout, resin, or the like when the ribbed portion is, for example, rotated into a bore such as that provided in rock in mining operations.

The core is typically a circular cylindrical core.

The ribbed portion may include two longitudinal raised portions which extend along the cylindrical core at circumferentially opposed positions. In certain embodiments, the raised portions define boundary regions between opposed longitudinal core sections, each core section including a plurality of spaced ribs and wherein ribs on opposed core sections are orientated in opposed directions. Accordingly, the ribbed portion may be rotated into a bore in either a clockwise or anticlockwise direction and still effect mixing or activation of a chemical adhesive such as resin, grout, or the like in the bore.

The ribs on one core section may be orientated in a left hand external screw-thread fashion and the ribs on the other core section are orientated in a right hand screw-thread fashion. In other embodiments, the raised portions define boundary regions between opposed longitudinal core sections, each core section including a plurality of spaced ribs and wherein ribs on opposed core sections are orientated in a substantially similar direction in a screw-thread fashion.

Each pair of adjacent ribs may stand proud of the core at a different height. The longitudinal raised portions typically stand proud at a lower height above the core than the ribs. The anchor bolt may be produced from steel which has been extruded and thereafter rolled. The threaded portion may include a nibbed region proximate its free end.

The ribs preferably alternate in height, adjacent ribs being about 1 mm and 0.6 mm in height and, accordingly, alternate ribs may be of equal height. Typically, the ribs have a rounded profile with a radius of curvature of about 0.5 mm.

WO 01/44621 PCT/IB00/01789 3 Still further in accordance with the invention there is provided an elongate rod, which includes a ribbed portion including an elongate circular cylindrical core on which a plurality of spaced ribs are provided, at least two adjacent ribs being of different height relative to the core.

The ribbed portion typically includes two longitudinal raised portions which extend along the cylindrical core at circumferentially opposed positions, the raised portions defining boundary regions between opposed longitudinal core sections, each core section including a plurality of spaced ribs. Ribs on opposed core sections may be orientated in opposed directions.

In certain embodiments, the ribs on one core section are orientated in a left hand external screw-thread fashion and the ribs on the other core section are orientated in a right hand screw-thread fashion. In other embodiments, the ribs on opposed core sections are orientated in a substantially similar direction in a screw-thread fashion.

Each pair of adjacent ribs may stand proud of the core at a different height. The longitudinal raised portions typically stand proud at a lower height above the core than the ribs. The elongate rod is typically extruded and thereafter rolled from steel. The threaded portion may include a nibbed region proximate its free end.

Preferably, the ribs alternate in height, adjacent ribs being about 1 mm and 0.6 mm in height. The ribs may have a rounded profile with a radius of curvature of about 0.5 mm.

The invention is now described, by way of example, with reference to the accompanying diagrammatic drawings.

In the drawings, WO 01/44621 PCT/IB0001789 4 Figure 1 shows a partly sectional view of an anchor bolt assembly in accordance with the invention in use; Figure 2 shows a top view of a ribbed portion of an anchor bolt, also in accordance with the invention; Figures 3 and 4 show side views, on an enlarged scale, of ribs of alternating height of the anchor bolt of Figure 2; Figure 5 shows a cross-sectional view of the ribbed portion of the anchor bolt of Figure 2 taken at V-V; Figure 6 shows a side view of the ribbed portion shown in Figure 2; Figure 7 shows a top view of a ribbed portion of a further anchor bolt, in accordance with the invention; Figures 8 and 9 show side views, on an enlarged scale, of ribs of alternating height of the anchor bolt of Figure 7; Figure 10 shows a cross-sectional view of the ribbed portion of the anchor bolt of Figure 7 taken at X-X; and Figure 11 shows a side view of the ribbed portion of the anchor bolt of Figure 7.

Referring to the drawings, reference numeral 10 generally indicates a rock anchor bolt assembly in accordance with the invention.

The assembly 10 includes a bearing arrangement 12 and an anchor bolt 14. The anchor bolt 14 includes an external screw-threaded portion 16 and a ribbed portion 18. As described in more detail below, the assembly 10 is typically used as a roof anchor in mining operations and is inserted in use into a bore 20 which has been drilled into rock 22 in a conventional fashion.

The bearing arrangement 12 includes a conventional hexagonal internally screw-threaded nut 24, which has a complemental screw-thread to the threaded portion 16, and a dogeared dome washer 26. It is however to be appreciated, that the bearing arrangement 12 may include a variety of different washers e.g. a conventional domed washer without a dogear, a flat washer, a ribbed dogeared washer, or the WO 01/44621 PCTIABOO/01789 like. Further, the threaded portion 16 includes a nib or slot 28 which is formed in a conventional fashion.

Referring in particular to Figures 2 to 6 of the drawings, the ribbed portion 18 includes a solid circular cylindrical core 30 which has -opposed longitudinal ridges 32, 34 which extend along its length and which define an interface or boundary region between first and second core sections 36, 38. The first core section 36 has adjacent ribs 40.1 and 40.2 which are each of a different height above a peripheral surface 42 of the core 30. Likewise, the second core section 38 has adjacent ribs 44.1, 44.2 which are substantially similar to the ribs 40.1, 40.2 respectively and also stand proud of a corresponding peripheral surface 46 of the second core section 38. The longitudinal ridges 32, 34 may stand proud marginally from the core 30 and typically stand proud about mm above the peripheral surfaces 42, 46 of the first and second core sections 36, 38 respectively.

The ribs 40.1, 40.2, 44.1, 44.2 are curved in crosssectional outline as shown at 48 in Figures 3 and 4. The radius of curvature is typically 1 mm and the ridges are typically about3.2 mm in width as shown by arrow 50. However, the ribs 40.1, 44.1 and 40.2, 44.2 are of different height. In particular, the ribs 40.1, 44.1 are about 0.6 mm in height as shown by arrow 52 (see Figure 4) and the ribs 40.2, 44.2 are about 1 mm in height as shown by arrow 54 (see Figure 3).

In the embodiment depicted in the drawings, each rib 40.1, 40.2, 44.1, 44.2, is curved relative to the peripheral surfaces 42, 46 of the core 30 (see Figure The ribs 40.1, 40.2, 44.1, 44.2, define a serpentine shape wherein the radius of curvature at a mid-point 56 of each rib 40.1, 40.2, 44.1, 44.2 is greater than the radius of curvature towards end points 58 of the ribs 40.1, 40.2, 44.1, 44.2. In other embodiments of the invention the ribs are substantially straight.

WO 01/44621 PCT/IB00/01789 6 The ribs 40.1, 40.2 provided on the first core section 36 and the ribs 44.1, 44.2 provided on the second core section 38 are orientated in opposed directions. The ribs 40.1, 40.2 are typically orientated in a right hand external screw-thread fashion and the ribs 44.1, 44.2 are typically orientated in a left hand screw-thread fashion.

Accordingly, the anchor bolt 14 may be rotated into the bore 20 in either a clockwise or anticlockwise direction and still effect mixing or activation of a chemical adhesive 60 as described in more detail below.

Referring in particular to Figures 7 to 11 of the drawings, reference numeral 70 generally indicates a ribbed portion of a further embodiment of an anchor bolt 72 in accordance with the invention. The rib portion 70 resembles rib portion 18 of the anchor bolt 14 and, accordingly, like reference numerals have been used to indicate the same or similar features unless otherwise indicated.

Unlike the ribbed portion 18 which has its ribs 40.1, 40.2 and its ribs 44.1, 44.2 orientated in opposed directions, the ribs 40.1, 40.2 and the ribs 44.1, 44.2 of the ribbed portion 70 are orientated in a similar fashion. In the embodiment depicted in Figures 7 to 11 of the drawings, the ribs 40.1, 40.2 and 44.1, 44.2 are orientated in a similar fashion as a right hand external screw-thread but, it is to be appreciated, that the ribs 40.1, 40.2 and 44.1, 44.2 may be orientated in a left hand external screw-thread fashion. As in the case of the ribbed portion 18, the pitch of the ribbed portion 70 of the anchor bolt 72 is also 14 as shown by arrow 62. Further, the ribs 40.1, 40.2, 44.1, 44.2 are generally orientated at an angle of about 65 degrees (see arrow 64) relative to the longitudinal ridges 32, 34.

In use, the curved nature of the ribs 40.1, 40.2, 44.1, 44.2 facilitates mixing of the chemical adhesive which typically secures the anchor bolt 14 in the bore 20. The chemical adhesive may be any conventional chemical adhesive such as resin or grout which requires an activation compound to initialize hardening. The chemical adhesive is WO 01144621 PCT/IB00/01789 7 typically provided in the form of a capsule and, accordingly, the anchor bolt 14 includes a V-shaped end 74 (see Figure 1) to break the capsule and thereby initiate setting. The curved ribs 40.1, 40.2, 44.1, 44.2 displace the chemical adhesive upon rotation of the anchor bolt 14 after the capsule has been broken and encourage mixing. In particular, the regions of the ribs 40.1, 40.2, 44.1, 44.2 proximate end points 58 have a steeper angle and facilitate or encourage mixing of the chemical adhesive whereas regions proximate the mid-points 56 facilitate an enhanced bond between the chemical adhesive and the anchor bolt 14, 72. Thus, a greater force is required to break the bond between the chemical adhesive and the anchor bolt 14 when the ribs lie at a flatter angle than when the ribs 40.1, 40.2, 44.1, 44.2 are at a greater angle.

As the anchor bolt 14 has ribs 40.1, 40.2 and ribs 44.1, 44.2 which are orientated in opposed directions, it is believed that it is an advantage of the anchor bolt 14 that it may be rotated either clockwise or anticlockwise into the bore 20. Accordingly, the anchor bolt 14 can be used with conventional apparatus for inserting conventional anchor bolts into bores in both a clockwise or anticlockwise direction. It is further believed, that the ribs 40.1, 44.1 and the ribs 40.2, 44.2 which have different heights 52, 54 respectively and which alternate in height along the ribbed portion 18, 70 provide enhanced operating characteristics for the anchor bolts 14, 72. In particular, the alternating height of the adjacent ribs 40.1, 40.2 and the ribs 44.1, 44.2 result in a chemical bond in the bore 20 which is not just between immediately adjacent ribs as in the case of conventional anchor bolts, but the bond is spread between spaced corresponding ribs 40.2 and 44.2.

Accordingly, unlike a conventional anchor bolt where a bond is localised between two adjacent ribs, the height difference between the immediately adjacent ribs 40.1, 40.2 and 44.1, 44.2 allows the bond to spread between the corresponding spaced ribs 40.2 and 44.2 thereby enhancing the bond.

Claims

1. An anchor bolt including an elongate anchor element, which includes a threaded portion and a ribbed portion, the ribbed portion including an elongate cylindrical core on which a plurality of spaced ribs are provided, at least two adjacent ribs being of different height relative to the core.

2. An anchor bolt as claimed in Claim 1, in which the ribs are curved in a serpentine fashion relative to a peripheral surface of the core.

3. An anchor bolt as claimed in Claim 1 or Claim 2, in which the ribbed portion includes two longitudinal raised portions which extend along the cylindrical core at circumferentially opposed positions.

4. An anchor bolt as claimed in Claim 3, in which the raised portions define boundary regions between opposed longitudinal core sections, each core section including a plurality of spaced ribs and wherein ribs on opposed core sections are orientated in opposed directions.

An anchor bolt as claimed in Claim 4, in which the ribs on one core section are orientated in a left hand external screw-thread fashion and the ribs on the other core section are orientated in right hand screw-thread fashion.

6. An anchor bolt as claimed in any one of the preceding claims 1 to 3 inclusive, in which the raised portions define boundary regions between opposed longitudinal core sections, each core section including a plurality of spaced ribs and wherein ribs on opposed core sections are orientated in a substantially similar direction in a screw-thread fashion.. WO 01/44621 PCT/IB00/01789 9

7. An anchor bolt as claimed in any one of the preceding claims 3 to 6 inclusive, in which each pair of adjacent ribs stands proud of the core at a different height.

8. An anchor bolt as claimed in any one of the preceding claims 3 to 7 inclusive, in which the longitudinal raised portions stand proud at a lower height above the core than the ribs.

9. An anchor bolt as claimed in any one of the preceding claims, which is produced from steel which has been extruded and thereafter rolled.

10. An anchor bolt as claimed in any one of the preceding claims, in which the threaded portion includes a nibbed region proximate its free end.

11. An anchor bolt as claimed in any one of the preceding claims, in which the ribs alternate in height, adjacent ribs being about 1 mm and 0.6 mm in height.

12. An anchor bolt as claimed in any one of the preceding claims, in which the ribs have a rounded profile with a radius of curvature of about 0.5 mm.

13. An anchor bolt assembly which includes an elongate anchor element including a threaded portion and a ribbed portion, the ribbed portion including an elongate cylindrical core on which a plurality of spaced ribs are provided, at least two adjacent ribs being of different height; and a bearing arrangement which includes a screw-threaded nut which is received on the threaded portion of the anchor element. WO 01/44621 PCT/IB00/01789

14. An anchor bolt assembly as claimed in Claim 13, in which the ribbed portion includes two longitudinal raised portions which extend along the cylindrical core at circumferentially opposed positions.

An anchor bolt assembly as claimed in Claim 14, in which the raised portions define boundary regions between opposed longitudinal core sections, each core section including a plurality of spaced ribs and wherein ribs on opposed core sections are orientated in opposed directions.

16. An anchor bolt assembly as claimed in Claim 15, in which the ribs on one core section are orientated in a left hand external screw- thread fashion and the ribs on the other core section are orientated in a right hand screw-thread fashion.

17. An anchor bolt assembly as claimed in Claim 13 or Claim 14, in which the raised portions define boundary regions between opposed longitudinal core sections, each core section including a plurality of spaced ribs and wherein ribs on opposed core sections are orientated in a substantially similar direction in a screw-thread fashion.

18. An anchor bolt assembly as claimed in any one of the preceding claims 14 to 17 inclusive, in which each pair of adjacent ribs stands proud of the core at a different height.

19. An anchor bolt assembly as claimed in any one of the preceding claims 14 to 18 inclusive, in which the longitudinal raised portions stand proud at a lower height above the core than the ribs. An anchor bolt assembly as claimed in any one of the preceding claims 13 to 19 inclusive, which is produced from steel which has been extruded and thereafter rolled.

WO 01144621 PCT/IB00/01789 11

21. An anchor bolt assembly as claimed in any one of the preceding claims 13 to 20 inclusive, in which the threaded portion includes a nibbed region proximate its free end.

22. An anchor bolt assembly as claimed in any one of the preceding claims 13 to 21 inclusive, in which the ribs alternate in height, adjacent ribs being about 1 mm and 0.6 mm in height.

23. An anchor bolt assembly as claimed in any one of the preceding claims 13 to 22 inclusive, in which the ribs have a rounded profile with a radius of curvature of about 0.5 mm.

24. An elongate rod, which includes a ribbed portion including an elongate circular cylindrical core on which a plurality of spaced ribs are provided, at least two adjacent ribs being of different height relative to the core.

An elongate rod as claimed in Claim 24, in which the ribbed portion includes two longitudinal raised portions which extend along the cylindrical core at circumferentially opposed positions, the raised portions defining boundary regions between opposed longitudinal core sections, each core section including a plurality of spaced ribs.

26. An elongate rod as claimed in Claim 25, in which ribs on opposed core sections are orientated in opposed directions.

27. An elongate rod as claimed in Claim 26, in which the ribs on one core section are orientated in a left hand external screw-thread fashion and the ribs on the other core section are orientated in a right hand screw-thread fashion.

28. An elongate rod as claimed in Claim 25, in which ribs on opposed core sections are orientated in a substantially similar direction in a screw-thread fashion. WO 01/44621 PCT/IBOO/01789 12

29. An elongate rod as claimed in any one of the preceding claims 25 to 28 inclusive, in which each pair of adjacent ribs stands proud of the core at a different height.

An elongate rod as claimed in any one of the preceding claims 25 to 29 inclusive, in which the longitudinal raised portions stand proud at a lower height above the core than the ribs.

31. An elongate rod as claimed in any one of the preceding claims 24 to 30 inclusive, which is extruded and thereafter rolled from steel.

32. An elongate rod as claimed in any one of the preceding claims 24 to 30 inclusive, in which the threaded portion includes a nibbed region proximate its free end.

33. An elongate rod as claimed in any one of the preceding claims 24 to 32 inclusive, in which the ribs alternate in height, adjacent ribs being about 1 mm and 0.6 mm in height.

34. An elongate rod as claimed in any one of the preceding claims 24 to 33 inclusive, in which the ribs have a rounded profile with a radius of curvature of about 0.5 mm.

A new anchor bolt, substantially as herein described and illustrated.

36. A new anchor bolt assembly, substantially as herein described and illustrated.

37. A new elongate rod, substantially as herein described and illustrated.