AU2006203066B2

AU2006203066B2 - Cable anchor system

Info

Publication number: AU2006203066B2
Application number: AU2006203066A
Authority: AU
Inventors: Brett Rossini
Original assignee: Wekaba Eng Pty Ltd
Current assignee: Wekaba Engineering Pty Ltd
Priority date: 2005-09-22
Filing date: 2006-07-18
Publication date: 2008-09-25
Anticipated expiration: 2026-07-18
Also published as: AU2006203066A1; ZA200507662B

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): Proline Trading 6 (Pty) Limited Invention Title: CABLE ANCHOR SYSTEM The following statement is a full description of this invention, including the best method of performing it known to me/us: 00 2 0 SCABLE ANCHOR SYSTEM SFIELD OF THE INVENTION s This invention relates to a cable anchor system, particularly a cable anchor system formed by a barrel and wedge.

IO

BACKGROUND TO THE INVENTION ND 10 Barrel and wedge are well known mechanisms are well known and are used in 0 cable anchor systems for supporting rock faces in a mine. They are also used for anchoring pre-tensioning or post-tensioning cables in reinforced concrete. While such mechanisms work effectively, they exert an inwardly radial compressive force on the cable being anchored which gradually increases as the tensile force on the cable is is increased. The problem with existing barrel and wedge mechanisms is that there is no means of preventing the radial compressive force on the cable from reaching critical levels. These high compressive forces result in a related stress riser in or near the barrel and wedge. Such high stress levels result in the cable failing at a point at or near the barrel and wedge, usually before the cable reaches its ultimate tensile strength.

SUMMARY OF THE INVENTION It would be advantageous if at least some embodiments of the cable anchor system provided an improved barrel and wedge cable anchor system that at least partially alleviates the above-mentioned problems.

In accordance with one aspect of the invention there is provided a barrel and wedge cable anchor system comprising a wedge assembly slidingly receivable inside a bore extending through a barrel, wherein an abutment surface, transverse to the direction of slide, is defined between the barrel and the wedge assembly.

N:'SydneyCases\Patent\6100-61999P61467.AU\Specis\P61467.AU Specification 2008-9-5.doc 8/09/08 O3 In one embodiment the abutment surface is normal alternatively to the direction cof slide. In an alternative embodiment the abutment surface is oblique to the direction of 00 slide.

In an embodiment the abutment surface to be formed by a step in the barrel bore, IND the step providing a shoulder separating a first section which tapers at least partially O along the length of the bore from a second section. The step may be a continuous circumferential step or a discontinuous step. Furthermore, the second section of the bore IND may be of constant diameter.

C1 In other forms the angle of taper to decrease at a point near the shoulder. There may be no angle of taper at a point near the shoulder.

In an embodiment the first sections extend over halfway along the length of the barrel.

A complementary abutment surface may further be defined on the wedge which may be formed at the narrow end of the wedge. This complementary abutment surface may be a flat surface normal to the direction of slide. Instead it may be formed by a complementarily shaped step on the outer surface of the wedge.

In an embodiment the bore of the barrel has more than one step formed thereon.

In an alternative embodiment of the invention, there is provided for the abutment surface to be formed by a flange projecting outwardly from the wedge, preferably from the wide end of the wedge.

In a yet further alternative embodiment of the invention, there is provided for the abutment surface to be formed by a separate component which is fixedly attachable to the inner wall of the barrel, such as a sleeve. Alternatively, the separate component may be fixedly attachable to the outer surface of the wedge.

The invention extends to a barrel for use in the barrel and wedge cable anchor system described above.

The invention further extends to a wedge for use in the barrel and wedge cable 004 anchor system described above.

In accordance with another aspect of the invention there is provided a barrel and wedge cable anchor system comprising: s a wedge assembly defining an abutment surface; and a barrel defining a bore, the bore including a tapering first section for slidingly ID receiving the wedge assembly, wherein an abutment surface is defined within the bore of the barrel, the abutment surfaces being transverse to the direction of slide, wherein, after a cable has been inserted into the wedge assembly and a tensile ID 10 force is applied to the cable, the wedge assembly is caused to move towards the Oabutment surface within the bore of the barrel, with the tapering first section of the bore causing a gradually increasing compressive force to be applied to the cable to hold it in place, so that when the wedge assembly's abutment surface abuts the abutment surface within the bore of the barrel, the wedge assembly can move no further and the is compressive force on the cable remains substantially constant.

In accordance with still another aspect of the invention there is provided a barrel for use in a barrel and wedge cable anchor system, the barrel defining a bore having a tapering first section for slidingly receiving a wedge assembly, the wedge assembly defining an abutment surface, wherein an abutment surface is defined within the bore of the barrel so that after a cable has been inserted into the wedge assembly and a tensile force is applied to the cable, the wedge assembly is caused to move towards the abutment surface within the bore of the barrel, with the tapering first section of the bore causing a gradually increasing compressive force to be applied to the cable to hold it in place, so that when the wedge assembly's abutment surface abuts the abutment surface within the bore of the barrel, the wedge assembly can move no further and the compressive force on the cable remains substantially constant.

BRIEF DESCRIPTION OF THE DRAWINGS Notwithstanding any forms which may fall within its scope, embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings in which: Figure 1 is a partially sectioned longitudinal view of an embodiment of a barrel for use in a barrel and wedge anchor in accordance with the invention; Figure 2 is a similar view of an alternative embodiment of a barrel; and Figure 3 is a similar view of an embodiment of a wedge for use in a barrel and 00 4a

O

0 wedge anchor in accordance with the invention.

eD SDETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION s One embodiment of a barrel for use in a barrel and wedge anchor is shown in Figure 1 and is made up of a cylindrical body having a circular bore extending D therethrough, the body having one rounded end as shown. Near the rounded end ¢C on the outer surface of the barrel is defined a circumferential slot Thus far, 0 the barrel described is of conventional construction.

SThe bore in the barrel is stepped in its length at to provide an abutment surface formed by a shoulder separating a first section which tapers along part of the length of the barrel from a second section which is of constant diameter.

An alternative barrel is shown in Figure 2, where the angle of taper decreases at a point near the shoulder One embodiment of a wedge (10) is shown in Figure 3 and is shaped and dimensioned to be received inside the first section of the barrel 1.1).

N:\Sydney\Cases\Paten\61000-61 999\P61 467AU\Specis\P61 467AU Specification 2008--5.doc 8/09/08

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The wedge (10) is made up of a hollow frusto-conical body (11) which is split longitudinally into three equal segments The segments (12) are held together by 00 way ofa circlip (not shown) fitted in a circumferential slot (13) near the wide end (14) of the body The inner wall (15) of the segments (12) has a plurality of sharp circumferential serrations (16) for providing a friction fit between the wedge (10) and IDsteel cable being anchored. The wedge (10) is made from hardened steel. Thus far the O wedge (10) described is of conventional construction.

IDThe narrow end (17) of the wedge (10) is flat to provide a complementary abutment surface against the step 6.1) when the wedge (10) is in an operative position.

However, it will be appreciated that the narrow end of the wedge (10) may be alternatively shaped to provide an abutment surface complementary to the step formed in the bore In use, a steel cable to be anchored is inserted in the wedge in conventional fashion. When a tensile force is applied to the cable, the wedge serrations engage the member and the wedge is caused to move towards the shoulder in the barrel. The segments are urged by the tapering section of the bore against the cable, thereby causing a compressive force to be applied to the cable and holding it between the segments. This radial compressive force exerted on the member increases gradually as the wedge is urged inwardly into the barrel. Once the flat end of the wedge abuts the shoulder, the radial stresses remain substantially constant.

It will be appreciated that embodiments of the cable anchor system can provided a simple yet effective means for alleviating the radial stresses exerted on a steel cable being anchored.

Several modifications to this embodiment are possible without departing from the scope of the cable anchor system. The abutment surface, for instance, may have a number of different shapes or configurations. The bore may have a step which is oblique to the direction of slide. There may also be more than one step formed in the bore. There may also be a complementary step formed on the outer surface of the wedge. The abutment surface may instead be a flange projecting radially into the bore or radially outwardly from the outer surface of the wedge. The abutment surface may further instead be a separately manufactured component, such as a sleeve, which may be fixed to the outer surface of the wedge or to the inner wall of the barrel.

N 6 In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary 0 implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the IDinvention.

It is to be understood that, if any prior art information is referred to herein, such IDreference does not constitute an admission that the information forms a part of the common general knowledge in the art, in Australia or any other country.

Claims

1. A barrel and wedge cable anchor system comprising: a wedge assembly defining an abutment surface; and a barrel defining a bore, the bore including a tapering first section for slidingly receiving the wedge assembly, wherein an abutment surface is defined within the bore IND of the barrel, the abutment surfaces being transverse to the direction of slide, Cc wherein, after a cable has been inserted into the wedge assembly and a tensile Sforce is applied to the cable, the wedge assembly is caused to move towards the ND 10 abutment surface within the bore of the barrel, with the tapering first section of the bore causing a gradually increasing compressive force to be applied to the cable to hold it in place, so that when the wedge assembly's abutment surface abuts the abutment surface within the bore of the barrel, the wedge assembly can move no further and the compressive force on the cable remains substantially constant.

2. An anchor system as claimed in claim 1, in which the abutment surfaces are substantially normal to the direction of slide.

3. An anchor system as claimed in claim 1, in which the abutment surfaces are oblique to the direction of slide.

4. An anchor system as claimed in any of the preceding claims, in which the abutment surface within the bore of the barrel is formed by a step in the barrel bore, the step providing a shoulder separating the tapering first section from a second section of the bore.

An anchor system as claimed in claim 4 in which the step is a continuous circumferential step or a discontinuous step.

6. An anchor system as claimed in either claim 4 or claim 5, in which the second section of the bore is of constant diameter.

7. An anchor system as claimed in either claim 4 or claim 5, in which the angle at which the tapering first section tapers decreases at a point near the shoulder.

8. An anchor system as claimed in any one of the claims 4 to 7, in which the tapering first section extends over halfway along the length of the barrel.

N:\Sydney\Cases\Patent\61OOO-61999\P61467ALASpecisP61467AU Speification 20DS-9-5.doc 8/09/08 00 8 S9. An anchor system as claimed in any one of claims 4 to 8, in which the bore of a) the barrel has more than one step formed thereon.

10. An anchor system as claimed in any of the preceding claims, in which the wedge assembly's abutment surface is formed at a narrow end of the wedge assembly. c

11. An anchor system as claimed in claim 10, in which the wedge assembly's Sabutment surface is a flat surface normal to the direction of slide. IND

12. An anchor system as claimed in any of the preceding claims, in which the abutment surfaces are complementary.

13. An anchor system as claimed in claim 5, in which the wedge assembly's abutment surface comprises a complementarily shaped step on the outer surface of the wedge assembly.

14. An anchor system as claimed in any one of claims 1 to 9, in which the wedge assembly's abutment surface is formed by a flange projecting outwardly from the wedge assembly.

An anchor system as claimed in claim 14, in which the flange projects from a wide end of the wedge.

16. An anchor system as claimed in any one of claims 1 to 3, in which the abutment surface is formed by a separate component which is fixedly attachable to the inner wall of the barrel or to the wedge.

17. An anchor system as claimed in claim 16, in which the separate component is formed by a sleeve.

18. A barrel for use in a barrel and wedge cable anchor system, the barrel defining a bore having a tapering first section for slidingly receiving a wedge assembly, the wedge assembly defining an abutment surface, wherein an abutment surface is defined within the bore of the barrel so that after a cable has been inserted into the wedge assembly and a tensile force is applied to the cable, the wedge assembly is caused to move towards the abutment surface within the bore of the barrel, with the tapering first NASydneyCases\Patent\61 000-61999\P61 467AU\Specis\P61 467.AU Speofication 2008-9-5.doc 8/09/08 00 O section of the bore causing a gradually increasing compressive force to be applied to the C. cable to hold it in place, so that when the wedge assembly's abutment surface abuts the abutment surface within the bore of the barrel, the wedge assembly can move no further and the compressive force on the cable remains substantially constant.

19. A barrel as claimed in claim 18, in which the abutment surface within the bore IsN of the barrel is formed by a step, the step providing a shoulder separating the tapering O Cc first section from a second section of the bore. ID 10

20. A barrel as claimed in claim 19 in which the step is a continuous circumferential 0 step or a discontinuous step. N: Sydney Casesatent61000-61 999\P61467AU\Specis\P61467AU Speciflcabon 2008-9-5.doc W09/08