GB2263287A

GB2263287A - A cable bolt

Info

Publication number: GB2263287A
Application number: GB9200809A
Authority: GB
Inventors: John Leslie Edward Finnis
Original assignee: DYWIDAG SYSTEMS
Current assignee: DYWIDAG SYSTEMS
Priority date: 1992-01-15
Filing date: 1992-01-15
Publication date: 1993-07-21
Anticipated expiration: 2012-01-15
Also published as: GB2263287B; GB9200809D0

Abstract

The cable bolt is made by de-stranding helically laid wires 1 to 7, Fig. 2, so that they lie generally parallel with each other, whereby the wires, having a helical twist therein, are provided with alternate areas of larger and smaller diameters 20, 19. The wires are then tied, Fig. 4, at those areas of smaller diameter 19 with plastic strap fasteners 21 to complete the cable bolt. <IMAGE>

Description

A CABLE BOLT The invention relates to a method of making a cable bolt and a cable bolt made in accordance with such a method.

A cable bolt is known from EP-A-163479 which is formed by de-stranding helically laid wire of a cable and twisting the wires together in a direction opposite to the direction of the original twist so that over at least part of its length there is provided a cable bolt which has alternate areas of larger and relatively smaller diameters.

In order to twist the wires together in the direction opposite to the original twist, it is necessary in EP-A-163479 to use complex apparatus which requires not only a de-stranding section but also a section to twist the wires together in the direction opposite to the original twist. An object of the present invention is to provide a method of making a cable bolt and a cable bolt made in accordance with such a method which requires less complex apparatus.

According to one aspect of the invention there is provided a method of making a cable bolt from a strand comprising a plurality of helically laid wires including the steps of de-stranding the helically laid wires so that they lie generally parallel with each other and tying the generally parallel wires together at intervals so as to provide a cable bolt having alternate areas of larger and relatively smaller diameters.

When the wires are de-stranded, each of the wires will have a helical twist therein which provide first sections of the generally parallel wires which tend to lie closer to each other than intermediate second sections. The wires are preferably tied together at the first sections. With the present invention it is a simple and straightforward operation to tie the wires together without having to impart to the destranded wires a further twist opposite to the direction of original twist. Therefore, apparatus for producing cable bolts in accordance with the invention is less complex than that described in EP A-163479.

Preferably, the wires are tied together while one end of each of the de-stranded wires is positioned in an aperture formed in a rotatable member of apparatus for de-stranding the wires. The wires can then be severed to enable the cable bolt to be detached from the apparatus.

According to another aspect of the invention there is provided a cable bolt comprising a plurality of wires extending generally parallel with each other after having been de-stranded from a strand comprising a plurality of helically laid wires, the de-stranded wires being tied together at intervals to form alternate areas of larger and relatively smaller diameters.

The wires may be tied by means of plastics strap fasteners or other suitable means.

Preferably, the wires are tied together at positions where the generally parallel wires tend naturally to lie closer together than at alternate positions due to a helical twist in each individual de-stranded wire.

A method and a cable bolt in accordance with the invention will now be described by way of example with reference to the accompanying drawings in which: Fig.l is a diagrammatic elevation of apparatus used in the production of a cable bolt in accordance with the invention, Fig.2 is a diagrammatic perspective view of part of the apparatus shown in Fig.1 illustrating a rotatable de-stranding die, Fig.3 is an enlarged elevation of part of a destranded cable showing the way in which the wires can be drawn together for tying.

Fig.4 is a diagrammatic elevation of a cable bolt in accordance with the invention.

In Fig.1, a steel strand 10 is wound as a coil 12 and is fed from the coil by a hydraulic pusher unit 13 to a de-stranding section 14. The strand 10 is formed from helically wound wires 1 to 7. Part of the destranding section is shown in Fig.2 and comprises a de-stranding die 15 mounted for rotation on rollers 16. The die is formed with apertures 17 through which the individual wires 1 to 7 of the strand 10 pass slidably. When setting up the apparatus the wires 1 to 7 are de-stranded manually and inserted through the apertures 17.

To de-strand the wires 1 to 7 when forming the cable bolt, the hydraulic pusher unit 13 urges the strand 10 forwardly so that the wires 1 to 7 are pushed through the apertures 17 simultaneously rotating the die 15 on the rollers 16. The de-stranded wires are supported on an elongate table 18 and the action of the hydraulic pusher unit 13 is continued until the desired length of de-stranded wires 1 to 7 is obtained.

As the wires 1 to 7 pass through the die they take up a position generally parallel with each other, i.e.

substantially around each other, as will be apparent from Fig.2 although each individual wire has a helical twist. The helical twist tends to bring alternate first sections 19 of the parallel wires closer to each other than intermediate second sections 20. Therefore, it is relatively easy to draw together the wires 1 to 7 at sections 19 as in Fig.3 to form alternate areas of small diameter along the length of the wires 1 to 7 with areas of larger diameter 20a in between. Once the sections 19 are drawn together, they can be tied by means of plastics strap fasteners 21 or other suitable means.

Once the sections 19 have been tied together, the wires 1 to 7 are cut to enable a completed cable bolt 22 to be detached from the apparatus as in Fig.4 leaving a length of wire projecting through each aperture 17 ready to produce the next cable bolt.

It will be appreciated that the method of producing the cable bolt is most straightforward and does not require the complex machinery of EP-A-163479.

Claims

1. A method of making a cable bolt from a strand, the strand comprising a plurality of helically laid wires, including the steps of destranding the helically laid wires so that they lie generally parallel with each other and tying the generally parallel wires together at intervals so as to provide a cable bolt having alternate areas of larger and relatively smaller diameters.

2. A method of making a cable bolt from a strand according to Claim 1 including tying the wires together at those sections having relatively small diameters

3. A method of making a cable bolt from a strand according to Claim 2 including tying the wires together while one end of each of the de-stranded wires is positioned in an aperture formed in a rotatable member of apparatus for de-stranding the wires

4. A method of making a cable bolt from a strand according to any preceding Claim including tying the wires together by means of a plastic strap fastener.

5. A method of making a cable bolt from a strand substantially as described herein with reference to the accompanying drawings.

6. A cable bolt comprising a plurality of wires extending generally parallel with each other after having been de-stranded from a strand comprising a plurality of helically laid wires, the de-stranded wires being tied together at intervals to form alternate areas of larger and relatively smaller diameters.

7. A cable bolt according to Claim 5 wherein the wires are tied together at positions where the generally parallel wires tend to lie close together than at alternate positions due to a helical twist in each individual de-stranded wire.

8. A cable bolt according to Claim 5 or 6 where the wires are tied by means of a plastic strap fastener.

9. A cable bolt constructed and arranged substantially as described herein with reference to the accompanying drawings.