GB2187527A - Fixing devices - Google Patents

Abstract

A fixing device for example a wall bolt or cavity wall tie, has a rod portion (11) carrying a radially expansible anchoring mechanism (12). Mechanism (12) comprises a sleeve (20) axially interposed between a stop (21) on the rod (11) and a member (22) running on a screw-threaded part on the rod (11). The sleeve (20) is slit axially to form fingers (20D) and has a cone-shaped bore (20B). The member (22) has an external surface which is multi- facetted and is diametrically dimensioned at least to enter partly within the bore (20B) of the sleeve (20) prior to any substantial radial expansion of the sleeve fingers (20D). Member (22) may be a hexagonal nut. <IMAGE>

Description

SPECIFICATION Fixing devices This invention relates to fixing devices having a rod portion carrying a radially-expansible anchoring mechanism for secural within a bore formed in a structure.

Various forms of such devices are well known, for example, wall bolts and cavity wall ties, and comprise anchoring mechanisms having a sleeve axially interposed between a stop on the rod portion and a member running on a screw-threaded part of the rod portion. In one example the sleeve is made of resiliently deformable material and the member has an abutment face for thrust loading the sleeve to effect axial compression and radial expansion.

In another example the sleeve is metallic, axially slit part way along its length to form fingers, and has a cone shaped bore which engages an externally coned surface on the member so that running movement of the member effects radial expansion of the sleeve by deformation of the fingers thereof.

It is an object of the present invention to provide a new and improved device having a rod portion carrying a radially-expansible anchoring mechanism for secural within a bore formed in a structure.

According to the present invention there is provided a fixing device having a rod portion carrying a radially expansible anchoring mechanism for secural within a bore formed in a structure, said anchoring mechanism having a sleeve axially interposed between a stop on the rod portion and a member running on a screw-threaded part of the rod portion, the sleeve being metallic, axially slit part way along its length to form fingers and having a cone-shaped bore, wherein said member has an external surface which is multifacetted and is diametrically dimensioned at least to enter partly within the sleeve bore prior to any substantial radial expansion of the sleeve fingers by running movement of said member.

Preferably said member is relatively short in axial length in comparison with the length of the sleeve fingers.

The multifacetted surface of the member may have any number of facets. Six facets is preferred. each facet may be axially tapered, but an absence of axial tapering is preferred.

It is further preferred that each facet is planar.lt is believed that the advantages of the present invention arise from the presence of the projecting edges formed at the junction of adjoining facets. Each such projecting edge may have an axially tapered lead portion to facilitate at least partial entry of the member into the sleeve bore prior to any substantial radial expansion of the sleeve fingers.

The anchoring mechanism may be made of stainless steel components. Conveniently the sleeve and/or member is 'Sheradized' by deposition of zinc which acts as a dry lubricant during running movement of said member.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows a device in accordance with the present invention, the device being in the form of a cavity wall tie; Figure 2 is a view of one end of the Fig. 1 tie shown to a larger scale in the interests of clarity; Figure 3 shows the Fig. 2 tie end after use; and Figure 4 is a view of the other end of the Fig. 1 tie shown to a larger scale in the interests of clarity.

The cavity wall tie 10 which is shown in the drawing comprises a stainless steel rod 11 carrying a radially-expansible anchoring mechanism 12 at one end, a radially-expansible anchoring mechanism 13 at its other end and an O-ring 14 between mechanisms 12 and 13. The tie 10 is fitted to a cavity wall structure comprising an inside wall 15 and an outside wall 16, walls 15, 16 being separated by an air gap 17. The tie 10 is retrofitted to the structure by initially boring a hole 18 from the outside wall 16 through into the inside wall 15 where the bore hole 18 has a blind end, and thereafter sliding the assembled tie 10 along the hole 18 until the tie seats against the blind end of the bore hole 18.

The mechanism 12 comprises a metallic sleeve 20 axially interposed between a stop 21 on the pertaining portion of rod 11 and a member 22 running on a screw-threaded part of the rod 11. Stop 21 is conveniently formed by a hexagonal nut 21A mounted by screw threads on the rod 11 and an upstand formation 21B formed on the rod 11 by clenching.

The sleeve 20 has a parallel bore 20A which is greater in size than the rod 11. Bore 20A is formed at the end of the sleeve adjacent stop 21 and is sufficiently small to permit thrust abutment of the sleeve end face against the stop 21. Sleeve 20 also has a coned bore 20B the maximum diameter of which is presented at the end of the sleeve 20 adjacent the member 22 and throughout the length of the coned bore 20B there are four axially extending slits 20C in the sleeve 20 which thereby form four sleeve fingers 20D. In the illustrated embodiment member 22 is in the form of a standard hexagonal nut which is diametrically dimensioned to enter at least partially within coned bore 20B of sleeve 20 prior to any substantial expansion of sleeve fingers 20D.However, when mechanism 12 is actuated by rotation of rod 11 nut member 22 is caused to run on the rod 11 and move bodily within bore 20B causing the sleeve fingers 20D to distort and expand radially as shown in Fig. 3.

Mechanism 13 may be identical to mecha nism 12 or alternatively modified as shown in Fig. 4 such that the parallel bore 25A of sleeve 25 is secured to the rod 11 by screw threads, and preferably by an adhesive also, so that no movement of sleeve 25 occurs relative to the stop 27 formed in rod 11 during entry of the tie into the hole 13, or during actuation of mechanism 12 thereby eliminating unwanted expansion of the sleeve 25. Actuation of mechanism 13 is effected by rotation of member 26 on rod 11 and in this case member 26 is formed by an unthreaded nut component 26A and a threaded nut component 26B, the latter being radially undersized to facilitate engagement by a tube spanner within the confines of bore hole 18.

In the embodiment rod 11 is 6mm diameter with 6mm ISO threads, components 21 and 22 are standard 6mm threaded hexagonal nuts each 5mm in axial length, component 26A is a standard 6mm threaded hexagonal unit through bored to remove the threads, component 26B is a non-standard 6mm threaded hexagonal nut radially undersized by about 2mm and axially about 8mm long, sleeve 20 is 30mm in length, slits 20C are about 20mm in length and the external diameter of sleeve 20 is 12mm. Hole 18 is 12mm in diameter so that, when unexpanded, sleeves 20, 25 are a push fit in hole 18.

It has been found that mechanisms 12, 13 provide enhanced anchoring over prior art devices and higher torque values can be attained without damage to walls 15, 16. Consequently higher than normal loadings are attainable. Also, because member 22 moves bodily inside sleeve 20 as depicted in Fig. 3, the rod 11 is equally resistive to compressive and tensile axial loadings. Furthermore because of the hexagonal nature of the member 22 initial expansion of sleeve 20 appears to occur asymmetrically and a good starting grip is achieved in hole 18.

Claims (12)

1. A fixing device having a rod portion carrying a radially expansible anchoring mechanism for secural within a bore formed in a structure, said anchoring mechanism having a sleeve axially interposed between a stop on the rod portion and a member running on a screw-threaded part of the rod portion, the sleeve being metallic, axially slit part way along its length to form fingers and having a cone-shaped bore, wherein said member has an external surface which is multifacetted and is diametrically dimensioned at least to enter partly within the sleeve bore prior to any substantial radial expansion of the sleeve fingers by running movement of said member.

2. A fixing device as claimed in claim 1, wherein said member is relatively short in axial length in comparison with the length of the sleeve fingers.

3. A fixing device as claimed in either preceding claim, wherein said member has planar facets.

4. A fixing device as claimed in claim 3, wherein the projecting edges formed at the junction of adjoining facets each have an axially tapered lead portion to facilitate at least partial entry of the member into the sleeve bore prior to any substantial radial expansion of the sleeve fingers.

5. A fixing device as claimed in claim 4, wherein the member has six facets each of which is free of axial tapering.

6. A fixing device as claimed in any preceding claim, wherein each component of the anchoring mechanism is made of stainless steel.

7. A fixing device as claimed in claim 6, wherein a dry lubricant is provided at the interface between the sleeve and the member.

8. A fixing device as claimed in claim 7, wherein the dry lubricant is zinc.

9. A fixing device as claimed in claim 7, wherein the dry lubricant is provided by Sheradization of the sleeve and/or member.

10. A fixing device as claimed in any preceding claim, and which is in the form of a wall bolt.

11. A fixing device as claimed in any one of claims 1-9 and which is in the form of a cavity wall tie.

12. A fixing device as claimed in claim 11 and substantially as hereinbefore described with reference to the accompanying drawing.