GB2549084A

GB2549084A - Fixing

Info

Publication number: GB2549084A
Application number: GB1605281.3A
Authority: GB
Inventors: John Haigh Philip
Original assignee: Hl Eng Contractors Ltd
Current assignee: Hl Eng Contractors Ltd
Priority date: 2016-03-30
Filing date: 2016-03-30
Publication date: 2017-10-11
Anticipated expiration: 2036-03-30
Also published as: GB201605281D0; GB2549084B

Abstract

A fixing (1) for use in concrete or masonry includes shank (2) having at least one formation (3), such as teeth or a thread, projecting outwardly from the shank. The or each formation (3) is configured such that, when the fixing (1) is driven into a bore (4) in the concrete or masonry, the or each formation (3) engages with the material surrounding the bore to hold the fixing (1) in the bore while leaving a clearance between the shank (2) and the concrete or masonry. There is at least one passageway along the shank (2) to permit fluid communication (e.g. for resin (6) or adhesive) between the fixing (1) and the bore.

Description

FIXING

Field of the Invention

This invention relates to a fixing, for example for attaching articles to a concrete or similar body.

Background to the Invention

Mounting walkways on concrete channels used in sewage works and the like is conventionally carried out using fixings cast in the wall of the channels to attach walkway mounting brackets. A problem with this is that, in time, the interaction between the concrete and the fixing - a threaded stud, for example - in damp conditions leads to corrosion and ultimately failure of the fixing, which in turn can lead to collapse of the walkway.

Installing replacements can be carried out by drilling into the channel walls and then installing a fixing stud or screw, but the use of conventional expanding inserts in the hole may be undesirable when the fixing is near an edge of a concrete structure, as would be the case with installation of walkways along the upper edge of the channels, because of the risk of cracking of the concrete due to the tensile stresses induced in the concrete. Other forms of fixing are available, for example a screw having a specially formed and hardened external thread is screwed into a hole drilled in the concrete, the external thread cutting its own corresponding internal thread in the concrete surrounding the hole.

It is desirable to be able to secure fixings using self-curing resin. However, because the resin needs to cure before the fixing can be placed under tension, it is necessary to carry out the work in two stages, with the refitting of the mounting brackets being completed when the resin has cured sufficiently. In practice, this increases installation time, so increasing costs.

There is therefore a need for a fixing that gives the strength and durability of resin-anchoring, but which can be installed and tensioned in a single operation. Summary of the Invention

The present invention provides a fixing for use in concrete or masonry, comprising a shank insertable in a bore in the concrete or masonry and having at least one formation thereon engageable with the wall of the bore to resist removal of the fixing from the bore and at least one passageway along the shank and through or around the formation to permit fluid communication from the end of the fixing in the bore along and around the fixing within the bore.

The or each formation preferably projects outwardly from the shank and is configured such that, when the fixing is driven into a bore in the concrete or masonry, the or each formation engages with the material surrounding the bore to hold the fixing in the bore while leaving a clearance between the shank and the concrete or masonry. The formation projecting outwardly from the shank may comprise a coarse external thread around the shank, the thread having a depth and configuration such that, when the fixing is screwed into a bore drilled into the concrete or masonry, the thread cuts into the surrounding concrete or masonry sufficiently to hold the fixing in place while leaving a clearance between the shank and the concrete or masonry.

Alternatively, the formations may comprise a plurality of prongs or teeth which may be configured to deflect or distort, or may simply cut into the wall of the bore during insertion, to permit the fixing to be hammered into the bore but which engage the material surrounding the bore to resist removal of the fixing from the bore.

In another embodiment, the fixing may take the form of a bar having at one end thereof an external screw thread and the other end a shank portion with a tapering wedge portion at the free end thereof, the wedge portion having a maximum diameter at the end of the bar, the formation comprising a sleeve slidably surrounding the shank such that tension exerted on the bar draws the wedge into the sleeve to expand the sleeve into engagement with the material surrounding the bore to hold the fixing in the bore, the wedge and the shank being formed with at least one groove or flute therein whereby resin introduced into the bore may flow along and around the shank.

The invention also provides, according to one embodiment, a method of attaching an article to a concrete or masonry body, comprising drilling into the body to form a bore, introducing into the bore a quantity of a self-curing resin, driving a fixing according to the invention into the bore so that the or each formation engages or cuts into the material surrounding the bore to hold the fixing in place and the resin is displaced by the fixing to flow through and fill the clearance along the length of the shank, and then allowing the resin to cure.

In another embodiment, the invention provides a method of attaching an article to a concrete or masonry body, comprising drilling into the body to form a bore, driving a fixing according to the invention into the bore so that the or each formation engages or cuts into the material surrounding the bore to hold the fixing in place, introducing into the bore a quantity of self-curing resin so as to flow through and fill the clearance along the length of the shank, and then allowing the resin to cure. Preferably, a fixing is used which has a passage therethrough along the longitudinal axis thereof and injecting the quantity of resin through said passage so that the resin flows from the fixing into the end of the bore and from there is displaced back through the clearance to fill the clearance along the length of the shank.

The screw or stud can be used in fixing in concrete, masonry or rock by drilling a hole having a diameter less than the major diameter of the external thread of the screw or stud but greater than the diameter of the shank of the screw or stud so as to leave a space between the hole and the shank, introducing a curable resin into the hole, screwing the screw or stud into the hole so that the thread cuts into the material surrounding the hole and the flutes mix and distribute the resin along the space between the hole and the shank. The engagement of the thread with the wall of the hole holds the screw or stud sufficiently to allow for attachment of the brackets or the like, while the resin, when cured, ensures that the screw or stud is firmly and permanently secured in the hole.

In one method of the invention, the bracket comprises a face for engagement with the body, said face having at least one pin projecting therefrom, and the method comprises drilling into the body to form at least one further bore corresponding to the or each pin, introducing self-curing resin into the or each further bore, mounting the bracket with the or each pin inserted into a respective further bore and then securing the bracket using the fixing.

Brief Description of the Drawings

In the drawings, which illustrate exemplary embodiments of the invention:

Figure 1 is a cross-sectional view of a screw installed in a bore in concrete;

Figure 2 is a side elevation of a fixing having a threaded socket therein;

Figure 3 is a top plan view of the fixing of Figure 2;

Figure 4 is an isometric view from above of the fixing of Figures 2 and 3;

Figure 5 is an end elevation of a pipe supporting bracket fixed in accordance with the invention;

Figure 6 is an end elevation of an alternative pipe supporting bracket;

Figure 7 is an end elevation of a further embodiment of pipe supporting bracket;

Figure 8 illustrates an alternative form of the fixing shown in Figures 2, 3 and 4;

Figure 9 is a cross-sectional view of an alternative form of screw to that shown in Figure 1, again installed in a bore in concrete;

Figure 10 is a partial cross-sectional view of yet another form of fixing; and

Figure 11 is a cross-sectional view of a bracket fixed according to another method of the invention.

Detailed Description of the Illustrated Embodiment

Referring first to Figure 1, a screw 1 has a reduced shank portion 2 around which is formed a triple-start thread 3 having a coarse pitch such that there are regions of the shank or lands between successive turns of the thread. The thread 3 has a height such that the tips of the thread will cut into the concrete sufficiently to hold the fixing against removal from a bore in concrete or the like, while leaving a clearance between the shank and the bore.

In use, a bore 4 is drilled into a body of concrete 5 and a quantity of selfcuring resin 6 is introduced into the bore. This may be done by injection of the resin, or by introducing a rupturable package of resin. The screw 1 is then driven into the bore using a suitable driving tool, which may for example cooperate with a hexagonal head 7 on the screw. The screw thread 3 cups into the concrete of the bore, forming its own internal thread and permitting the screw to drive into the bore. On encountering the resin, the forward progress of the screw forces resin along the clearance between the shank portion two of the screw and the bore, and between the terms of the thread, until the clearance is filled. While the engagement of the thread with the bore enables the screw to be tightened to mount an article in place against the concrete surface, for example a mounting bracket for a walkway, the hearing of the resin ensures that the article is held securely. Disruption to the surrounding concrete is minimised, and the requirement for the installer to return to complete the installation after the resin has cured is removed.

It will be appreciated that the screw illustrated in Figure 1 could be a stud having a threaded portion outside the bore for mounting bracket or the like using a threaded nut. Figures 2 to 4 show another possible embodiment of fixing comprising a generally cylindrical body 10 formed with a triple-start thread 11 along its length, configured to cut into a bore drilled into concrete or masonry to form its own internal thread in the bore sufficient to draw the fixing into position and to hold it, while leaving a clearance between the body 10 and the bore through which resin can pass when displaced by the progress of the fixing into the bore. The body 10 has an internal socket 12 provided with a conventional internal thread, for example to receive a machine screw, opening through a hexagonal socket 13 for engagement by a hexagonal driving tool, for example an Allen key, by which the fixing can be screwed into place. Again, the fixing may be installed and used for mounting articles to a surface in a single installation stage, with only the need to allow time for full curing of the resin before applying full load to the article.

Figures 5 to 7 illustrate pipe-mounting brackets that can be attached to a concrete or masonry surface using the fixings of the invention. The bracket shown in Figure 5 has a cruciform-section post 20 extending from a mounting plate 21 and carrying on opposed sides arms 22 for attachment of saddle clips 23 holding pipes 24. The embodiment shown in Figure 6 has a pair of posts 25, each having a mounting plate 26 for attachment to a masonry surface using screws or studs according to the invention. The posts 25 have two cross arms 27 extending between them, to which saddle clips 23 can be attached to hold the pipes 24. The embodiment shown in Figure 7 has a single cruciform post 30 carried on a mounting plate 31. The post 30 mounts on the sides and at the end thereof pipe mountings 32 in the form of two-part ring mountings, the two parts being held together by screws in conventional manner.

Figure 8 illustrates an alternative fixing to that shown in Figures 2 to 4. A cylindrical body 40 has a plurality of spikes 41 arranged around the cylindrical surface. The spikes 41 are configured to permit the body 40 to be hammered into a bore drilled into concrete or the like, but to engage the internal surface of the bore and to cut into it, to resist extraction of the body 40 from the bore. Again, a clearance remains between the body 40 and the wall of the bore, so that resin introduced into the bore before the body 40 is hammered into place will be displaced along and fill the clearance so that, once the resin is cured, the body is held firmly in place. An internal socket 42 having a suitable internal thread may receive an externally threaded screw for the mounting of articles to the surface of the concrete. It will be understood that the spikes could be provided over only a portion of the shank to provide sufficient resistance to extraction while the screw is tensioned.

Figure 9 illustrates a modification to the screw of Figure 1 to permit introduction of the resin after the screw is driven into the bore in the concrete or masonry. The screw is generally identical to that of Figure 1 except for the provision of a passageway 50 extending through the screw and opening at each end thereof. The head 7 of the screw is provided with a recess 51 opening into the passageway 50, the recess receiving the tip of a resin-injecting nozzle. The resin is pumped through the passageway 50, filling any space in the bore at the end of the screw and then flowing along the shank of the screw between the thread turns until the clearance is filled with resin. Curing of the resin secures the screw in place and also ensures that no moisture can enter through the passageway 50.

Figure 10 illustrates an alternative fixing in accordance with the invention, in the form of a bar 60, provided with an external screw-thread 61 along a major part of the length thereof. One end is provided with a wedge formation 62 which tapers inwardly away from the free end of the bar and leads into a cylindrical shank portion 63 which is separated from the threaded portion 61 by a shoulder portion 64. A sleeve 65 is a loose fit around the shank and has on its exterior formations 66 which engage and grip the wall of the bore 67 in the concrete body 68 when the sleeve is expanded outwardly as hereinafter described. Grooves or channels 69 extend along the bar, opening through the wedge 62 and extending through the shank 63, the shoulder portion 64 and a part of the threaded portion 61.

The sleeve 65 is partially split along its length to facilitate expansion and to provide an area into which resin can flow during installation. In use, after the bore 67 is drilled into the concrete body 68, self-curing resin is introduced into the bore before the fixing is driven in to displace resin through the channels 69 to surround the fixing, filling the clearance between it and the bore completely. The article to be attached, represented at 70 in the diagram and having a bore therethrough, is located over the part of the fixing projecting from the body and a washer 71 is then located over the fixing before a nut 72 is threaded on to the nut and tightened to draw the wedge 62 forward into the sleeve 65, causing it to expand into contact with the bore, firmly holding the fixing in place. The resin can then be allowed to cure, ensuring that the fixing and the article it is mounting are held permanently in position.

Figure 11 illustrates a method of fixing a bracket according to one aspect of the invention. The bracket is represented in the Figure as a simple block 80, but it will be appreciated that it may have any form, for example suitable for supporting a walkway over a concrete channel. The bracket 80 is provided with a mounting hole 81 therethrough for receiving, for example, a screw fixing 82, of the type described with reference to Figure 1. Longer brackets may be provided with multiple holes 81. Projecting from the rear face 83 of the bracket 80, i.e. the face contacting the concrete body 84 on which it is to be mounted, are elongate pins 85. As illustrated, the bracket has two pins projecting on either side of the mounting hole, but it will be appreciated that other configurations are possible within the scope of the invention.

In use, the bracket 81 is mounted on a concrete body by drilling bores 86 and 87 into the body, the bore 86 corresponding to the mounting hole 81 and the bores 87 corresponding to the pins 85. Self-curing resin is then introduced into each bore and the bracket is then positioned so that the pins 85 are received in the resin-containing bores 87, while the screw 82 is driven into the bore 86, as described with reference to Figure 1, to hold the bracket in its final position while the resin cures to make the fixing permanent. The combination of the pins and the screw fixing means that the advantages of resin-bonded fixings are gained with a reduced amount of labour in installation and without the need for a return visit by the installers after the resin has cured. Although the pins 85, and their corresponding bores 87, are shown in the Figure as being smaller than the screw 82 and its bore 86, it will be appreciated that they may be of the same size or larger, depending upon the loading to be attained by the bracket in use.

It has been found that, for satisfactory fixing, a clearance of approximately 1 mm around the shank will be suitable.

While the invention has been described with reference to fixing in concrete or masonry, it will be appreciated that it is applicable to other materials, for example rock.

Claims

1. A fixing for use in concrete or masonry, comprising a shank insert-able in a bore in the concrete or masonry and having at least one formation thereon engageable with the wall of the bore to resist removal of the fixing from the bore and at least one passageway along the shank and through or around the formation to permit fluid communication from the end of the fixing in the bore along and around the fixing within the bore.

2. A fixing according to Claim 1, wherein the or each formation projects outwardly from the shank and is configured such that, when the fixing is driven into a bore in the concrete or masonry, the or each formation engages with the material surrounding the bore to hold the fixing in the bore while leaving a clearance between the shank and the concrete or masonry.

3. A fixing according to Claim 2, wherein the formation projecting outwardly from the shank comprises a coarse external thread around the shank, the thread having a depth and configuration such that, when the fixing is screwed into a bore drilled into the concrete or masonry, the thread cuts into the surrounding concrete or masonry sufficiently to hold the fixing in place while leaving a clearance between the shank and the concrete or masonry.

4. A fixing according to Claim 2, wherein the formations comprise a plurality of prongs or teeth which can deflect or distort to permit the fixing to be hammered into the bore but which engage the material surrounding the bore to resist removal of the fixing from the bore.

5. A fixing according to Claim 1, in the form of a bar having at one end thereof an external screw thread and the other end a shank portion with a tapering wedge portion at the free end thereof, the wedge portion having a maximum diameter at the end of the bar, the formation comprising a sleeve slidably surrounding the shank such that tension exerted on the bar draws the wedge into the sleeve to expand the sleeve into engagement with the material surrounding the bore to hold the fixing in the bore, the wedge and the shank being formed with at least one groove or flute therein whereby resin introduced into the bore may flow along and around the shank.

6. A fixing according to Claim 3, wherein the pitch of the thread is such as to leave a land portion of the shank between successive turns of the thread.

7. A fixing according to Claim 3 or 6, wherein the thread is a doublestart thread.

8. A fixing according to Claim 3 or 6, wherein the thread is a triple-start thread.

9. A fixing according to any of Claims 3, 6, 7 or 8, in the form of a screw having a head portion for engagement by a tool for applying torque thereto.

10. A fixing according to Claim 9, wherein the head portion is shaped to receive a spanner or like tool.

11. A fixing according to Claim 9, wherein the head portion contains a slot or socket for receiving a driving tool therein.

12. A fixing according to any of Claims 3, 6, 7 or 8, in the form of a stud having an attachment threaded portion arranged at the end opposite to the shank, the attachment threaded portion being engageable with an internally threaded attachment member.

13. A fixing according to Claim 3 or 4, in the form of a body having a threaded socket therein for receiving a fixing screw.

14. A fixing, substantially as described with reference to, and/or as shown in, any of Figures 1 to 4, or 8 to 11, of the drawings.

15 A method of attaching an article to a concrete or masonry body, comprising drilling into the body to form a bore, introducing into the bore a quantity of a self-curing resin, driving a fixing according to any preceding claim into the bore so that the or each formation engages the material surrounding the bore to hold the fixing in place and the resin is displaced by the fixing to flow through and fill the clearance along the length of the shank, and then allowing the resin to cure.

16. A method of attaching an article to a concrete or masonry body, comprising drilling into the body to form a bore, driving a fixing according to any of Claims 1 to 14 into the bore so that the or each formation engages the material surrounding the bore to hold the fixing in place, introducing into the bore a quantity of self-curing resin so as to flow through and fill the clearance along the length of the shank, and then allowing the resin to cure.

17. A method according to Claim 16, comprising using a fixing which has a passage therethrough along the longitudinal axis thereof and injecting the quantity of resin through said passage so that the resin flows from the fixing into the end of the bore and from there is displaced back through the clearance to fill the clearance along the length of the shank.

18. A method according to Claim 14, 15 or 16, wherein the article is a bracket for supporting a walkway.

19. A method according to Claim 14, 15 or 16, wherein the article is a bracket for supporting at least one pipe or cable.

20. A method according to Claim 18 or 19, wherein the bracket comprises a face for engagement with the body, said face having at least one pin projecting therefrom, and the method comprises drilling into the body to form at least one further bore corresponding to the or each pin, introducing self-curing resin into the or each further bore, mounting the bracket with the or each pin inserted into a respective further bore and then securing the bracket using the fixing.

21. A method of attaching an article to a concrete or masonry body, substantially as described with reference to any of Figures 1 to 4, or 8 to 11, of the drawings.