GB2466258A

GB2466258A - Fixing apparatus and method

Info

Publication number: GB2466258A
Application number: GB0822976A
Authority: GB
Inventors: Robert Justin Beveridge; Peter Bayles
Original assignee: BE INVENTIVE Ltd
Current assignee: BE INVENTIVE Ltd
Priority date: 2008-12-17
Filing date: 2008-12-17
Publication date: 2010-06-23
Also published as: GB0822976D0

Abstract

An apparatus for fixing an object to a wall surface having first and second layers spaced by a cavity comprises a support structure 22 arranged to bridge the cavity and to engage with the second layer. The apparatus also comprises means for dispensing an adhesive substance onto the internal surfaces of both the first and second layers so as to secure the apparatus thereto.

Description

FIXING APPARATUS AND METHOD

Field of the Invention

The present invention relates to a fixing apparatus and method and particularly, but not exclusively, to an apparatus and method for fixing an object to a wall or other surface. The invention finds advantageous application in the fixing of objects to so-called cavity walls, having an outer layer of plasterboard or the like, to which the object must be fixed, and a second or underlying layer spaced from the first layer by a cavity. Aspects of the invention relate to an apparatus and to a method.

Backciround of the Invention There are various forms of cavity wall used in the building industry. One form of cavity wall is known as a stud-wall or partition-wall. This type of wall generally comprises two layers of dry sheeting material, such as plasterboard, which are spaced apart by timbers or "studs" disposed at regular intervals between the layers.

Stud-walls are relatively cheap and easy to erect and are therefore often used to form internal walls or partitions.

The securing of objects to such walls can be difficult, owing to the relatively fragile nature of the plasterboard. A number of existing devices, adapted for securing objects to cavity walls, are available. Known generally as wall plugs or wall anchors, these devices are arranged to secure a standard threaded fastener, such as a screw, either to the outer plasterboard layer or to the underlying support structure.

Such devices are suitable for supporting only relatively light loads and tend to impose compressive, tensile and/or shear stresses on the outer plasterboard layer which can, in some cases, lead to damage or failure thereof. Furthermore, care must be taken during installation of these devices in order to prevent cosmetic damage to the plasterboard.

An alternative form of device for fixing objects to stud-walls is disclosed in EP0572296. This device comprises a flexible sheath or casing mounted on an internally threaded socket, the latter being arranged to receive, and threadedly engage with, a threaded fastener. The sheath can adopt a folded state, in which the device is arranged to be inserted through a hole drilled in the outer plasterboard layer, and a deployed state in which the sheath is flared outwardly. In use, the device in the folded state is inserted through the hole such that the sheath is disposed on the rear side of the plasterboard layer and a chemical adhesive, such as a curable resin mortar, is injected into the sheath through the drilled hole. The injected mortar causes the sheath to expand into the deployed position such that the mortar spreads across a portion of the rear surface of the plasterboard where it cures to fix the sheath, and hence the device, to the plasterboard.

The present applicants have discovered that the device of EP0572296 does not provide optimum performance. One reason for this is that the weight of the object is carried entirely by the outer plasterboard layer, meaning that the weight of object to be secured by the fixing is limited. Heavy loads may impose excess local stresses on the plasterboard which can lead to cracking or crumbling.

In addition, the weight of the object acting downwards, parallel to the surface of the wall, may cause a torque or moment to be applied to the device which tends to twist or rotate the device within the plasterboard. Due to the friable nature of the plasterboard, such twisting can result in the fastener becoming loose, such that the reliability of the fixing is reduced.

It is an aim of the invention to address these issues and to improve upon such known technology. Embodiments of the invention may provide a fixing apparatus, suitable for use with a cavity wall, which solves one or more disadvantages of existing fixing devices. Other embodiments of the invention may provide a method of fixing an object to a wall which solves disadvantages of known techniques. Further aims and advantages of the invention will become apparent from the following

description, claims and drawings.

Summary of the Invention

Aspects of the invention therefore provide an apparatus and a method as claimed in the appended claims.

According to another aspect of the invention for which protection is sought, there is provided an apparatus for fixing an object to a wall having a first layer and a second layer spaced from the first layer by a cavity, the apparatus comprising support means for bridging the cavity and cooperating with the first and second layers, and means for dispensing an adhesive substance onto internal surfaces of the first and second layers so as to secure the support means thereto.

Advantageously, an apparatus according to an aspect of the invention cooperates or engages with both the front and rear layers of a cavity wall and is secured to the internal surfaces thereof by means of an adhesive. The adhesive may be a chemical or epoxy resin or mortar which hardens when cured, or any other suitable adhesive.

This arrangement significantly improves load bearing performance compared with existing devices.

In an embodiment, the support structure comprises plug means having an internal bore for receiving said adhesive substance. The adhesive substance may be conveniently injected or deposited within the internal bore using a suitable application tool such as a syringe or dispensing gun.

In an embodiment, the support structure comprises an end cap portion adjustably coupled to the plug means for adjusting the length of the support structure. This advantageously enables the apparatus to be used with cavity walls of different depths, ensuring that the apparatus is able to cooperate and/or engage with both layers of the wall.

In an embodiment, the end cap portion comprises an internal bore extending therethrough and arranged to slidably receive a nozzle portion of the plug means.

In an embodiment, the end cap portion comprises means for engaging with the internal surface of the second layer, in use. The means for engaging may comprise a spike or other projection. In one embodiment, the projection is adapted to pierce a surface of the second layer. In one embodiment, the projection is adapted to abut or engage with a surface of the second layer.

By piercing or penetrating the second layer, the end cap portion can be securely coupled thereto and movement of the apparatus relative to the second layer can be reduced or substantially eliminated while the adhesive is allowed to cure. In addition, a cantilever effect is achieved, providing significantly greater resistance to bending moment, thereby improving the stability and reliability of the fixing and increasing load capacity.

In one embodiment, the first layer comprises a plasterboard layer or surface and the second layer comprises a brick or blocked wall. In one embodiment, both the first and second layers comprise plasterboard layers or surfaces.

In an embodiment, the end cap portion comprises at least one aperture for permitting said adhesive to be dispensed onto the internal surface of the second layer. The at least one aperture may be arranged to ensure relatively even distribution of the adhesive so that, when dispensed, the adhesive substantially surrounds the region of the end cap portion in contact with the internal surface of the second layer.

In an embodiment, the support structure comprises skirt means, slidably mountable on the plug means and arranged to at least partly define with the internal surface of the first layer a volume for retaining and or controlling said adhesive. The skirt may be broadly similar in form to the sheath-casing described in EP0572296.

In an embodiment, the plug means comprises at least one aperture arranged to fluidly connect the internal bore to the variable volume within the skirt means so as to permit the adhesive to be dispensed onto the internal surface of the first layer.

In an embodiment, the skirt means comprises a plurality of flexible and/or resilient leaves capable of adopting a plurality of positions including a folded position, in which the skirt means can be passed through a hole formed in the first layer, and a deployed position in which the leaves are splayed or flared radially outwardly under pressure of the adhesive substance retained therein.

The apparatus may comprise spring means disposed between the end cap portion and the skirt means and arranged to bias the end cap portion and the skirt means into pressing engagement with the internal surfaces of the first and second layers, respectively. This enables both the end cap portion and the skirt means to be pressed firmly against the respect internal surfaces, reducing adhesive loss from the skirt means and ensuring that movement of the apparatus relative to the wall is reduced or substantially eliminated while the adhesive is drying.

In an embodiment, the internal bore of the plug means is arranged to receive a threaded fastener or the like. The threaded fastener may comprise a conventional screw or bolt or, alternatively, a specific support member which is itself arranged to receive a threaded fastener.

Thus, in an embodiment, the support structure comprises a support member adapted to threadedly engage in the internal bore of the plug means, the support member including a blind bore adapted to receive a threaded fastener or the like.

In an embodiment, the support member comprises means for cooperating with a twist-drive tool so as to permit the support member to be twist-driven into the internal bore in the plug means. This may consist of a recess formed in a driving end of the support member that is adapted to receive the twist-drive tool, such as a hexagon key or a screwdriver.

In an embodiment, twist driving of the threaded fastener and/or the support member into the internal bore in the plug means hydraulically forces the adhesive substance through the or each aperture in the end cap portion and the plug means and onto the internal surfaces of the first and second layers, respectively. This arrangement facilitates dispensing of the adhesive substance.

In an embodiment, the support structure is formed from a plastics material. The support member may be formed from a generally rigid material such as a metal or plastics material.

According to a further aspect of the invention for which protection is sought, there is provided an apparatus for fixing an object to a cavity wall having first and second layers spaced by a cavity, the apparatus comprising means for engaging in a hole formed in the first layer, means for engaging or cooperating with the second layer, means for engaging with a threaded fastener and means for dispensing an adhesive substance onto internal surfaces of the first and second layers so as to secure the support structure thereto.

According to a still further aspect of the invention for which protection is sought, there is provided an apparatus as described in EP2097034, the improvement comprising means for engaging with a second layer of a cavity wall, and means for dispensing an adhesive substance onto internal surfaces of the first and second layers so as to secure the support structure thereto.

According to yet another aspect of the invention for which protection is sought, there is provided a method of fixing an object to a surface having a first layer and a second layer spaced from the first layer by a cavity, the method comprising inserting a support structure into a hole in the first layer, engaging a distal end of the support structure with the second layer and dispensing an adhesive substance onto internal surfaces of the first and second layers so as to secure the support structure thereto.

Within the scope of this application it is envisaged that the various aspects, embodiments, examples, features and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings may be taken individually or in any combination thereof.

Brief Description of Drawincis

The present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a cross-sectional view through a conventional stud-wall; Figure 2 is a perspective view of a component constituting part of an apparatus embodying the invention; Figure 3 is a perspective view of another component constituting part of an apparatus embodying the invention; Figure 4 is a perspective view of a further component constituting part of an apparatus embodying the invention; Figure 5 is a perspective view of a still further component constituting part of an apparatus embodying the invention; Figure 6 is a perspective view of an apparatus embodying the invention comprising the components of Figures 2-5 in partially assembled form; Figures 7a -7e illustrate steps of a method for fixing an object to a stud-wall using the apparatus of Figure 6; and Figures 8a -8b illustrate further steps of a method for fixing an object to a stud-wall using the apparatus of Figure 6.

Detailed Description of Embodiments of the Invention In the drawings, as far as possible, like reference numerals indicate like parts. It will be understood that any references to direction or orientation are used only by way of example and in the context of the drawings and are not intended to be limiting in any way. Furthermore, the drawings are not necessarily shown to scale.

Referring firstly to Figure 1, this illustrates a cross section through a conventional stud-wall 10, as viewed from above. The stud-wall 10 comprises two layers of plasterboard sheeting 12, 14 joined in spaced apart relationship by vertically oriented timbers 16 (known as studs) defining a cavity 18 between the plasterboard layers.

The studs 16 are spaced apart along the wall at a predetermined distance (usually approximately 0.5-0.6m) and provide rigidity to the wall. In this case, the width of the cavity 18 defined between the front and rear layers of plasterboard 12, 14 is substantially equal to thickness of the studs 16. The cavity 18 may be provided with thermal or acoustic insulation (not shown), if desired, or may be left empty.

As described above, the fixing of objects to stud-walls of this type is more difficult than with block work cavity walls since there is no rigid structure in which to insert a fastener. In some situations, it may be possible to use the studs as support for the fixing, but this requires an accurate knowledge of the position of the studs and favourable positioning thereof. Conventional wall-plug fixings and plasterboard anchors engage only with the front plasterboard layer which is friable and easily deformed, meaning that only relatively light loads can be supported by the fixing.

The device of EP0572296, described above, provides a fixing which also engages only with the front plasterboard layer but employs a chemical adhesive to secure the device the rear surface thereof. This device provides improved load carrying performance compared the convention wall-plug fixings and plasterboard anchors.

However, the maximum load that can safely be supported by the device is still relatively low and the adhesive does not completely prevent twisting or bending of the device within the front plasterboard layer.

Figures 2 to 6 show, in perspective view, components or parts of an apparatus 20 according to an embodiment of the invention that is intended to address one or more of the disadvantages of the known art. In the illustrated embodiment, the apparatus comprises four discrete components which are shown separately in Figures 2-5, and in partially assembled form in Figure 6.

The apparatus 20 comprises a support member, shown best in Figure 2, in the form of an elongate, generally cylindrical, bolt-like member 22 which is formed from a strong, substantially rigid and/or incompressible material such as steel, aluminium, zinc or other metal. Alternatively, a hard plastics material may be used, depending on the application.

A portion of the support member 22 adjacent to a first end 24 thereof is stepped radially outwardly to define a portion 25 of enlarged diameter. On the other hand, a portion 27 of the support member 22 adjacent to a second, opposite end 26 thereof is tapered. The main body portion 28 of the support member 22, extending between the enlarged diameter portion 25 and the tapered portion 27, is substantially constant in diameter.

The enlarged diameter portion 25 is shaped to define a recess for cooperation with a suitable tool which may be used to turn or twist-drive the support member 22. In the illustrated embodiment, the first end 24 of the support member 22 defines a hexagonal recess (not shown) for engagement with a hexagonal key. Alternatively, or in addition, the recess may be shaped for cooperation with a flat-or cross-head screwdriver or other twist-drive tool.

The support member 22 is provided with an external screw thread (not shown) formed on its outer surface and extending along the main body portion 28 thereof from the tapered portion 27 towards the enlarged diameter portion 25, in the manner of a conventional threaded bolt. The external screw thread may extend along the whole or just a part of the length of the main body portion 28, as desired.

The support member 22 is provided with a blind bore (not shown) which opens into the recess defined in the enlarged diameter portion 25 and extends coaxially from the first end 24 along approximately one half of the length of the support member 22.

The blind bore may, however, extend along a greater or lesser part of the support member 22, including along the full length thereof. The blind bore includes anchor means, in the form of an internal screw thread (not shown), formed on its internal surface which extends along almost the full length thereof.

The apparatus 20 also comprises plug means, best shown in Figure 3, in the form of an elongate, generally cylindrical tube 30, having first and second ends 34, 36 thereof and an internal bore 32 extending therebetween. A radially outwardly extending flange 31, the purpose of which is described below, is provided at the first end 34 of the tube 30.

The internal bore 32 is open at both ends and is sized and shaped to receive the support member 22 therein. The internal bore 32 thus comprises a first portion of larger diameter 35, corresponding to the enlarged diameter portion 25 of the support member 22; a tapered portion 37 corresponding to the tapered portion 27 of the support member 22; and a portion of substantially constant diameter 38, corresponding to the constant diameter portion 28 of the support member 22, extending between the portions 35, 37.

Circumferentially spaced, stiffening ridges 39 extend longitudinally from the first flange 31 to a point beyond the enlarged diameter portion 25. Also, circumferentially spaced, generally circular apertures 41 are disposed in the wall of the tube 30 at a point slightly beyond the end of the stiffening ridges 39.

In addition, a nozzle portion 40 having a reduced diameter extends from the tapered portion 37 to the second end 36 of the tube 30. The end of the nozzle portion 40 corresponding to the second end 36 of the tube 30 is provided with a radially outwardly extending flange 42 having a diameter comparable to outer diameter of the constant diameter portion 38. Stiffening ridges 44, circumferentially spaced around the circumference of the nozzle portion 40, extend longitudinally from the end of the constant diameter portion 38 to the flange 42, that is to say along the length of the tapered and nozzle portions 37, 40. Each ridge 44 has a radially outwardly projecting fin 46, the purpose of which is described below.

The apparatus 20 further comprises retaining means in the form of a frusto-conical skirt 50, shown best in Figure 4. The skirt 50 comprises a plurality of slits 52, extending from the base of the skirt 50 to a point close to the tapered end, that divide the skirt 50 into a plurality of generally trapezoidal, flexible sections or leaves 54. The leaves 54 are joined at their narrow ends to form a unitary body but are separable, and substantially independently movable, at their wider ends.

The tapered end of the skirt 50 is coupled to biasing means in the form of a compression spring 56. The spring 56 extends forwardly of the skirt 50, in axial alignment therewith, and defines an axial bore 58 extending therethrough from the base of the skirt 50 to the free end of the spring 56. The axial bore 58 is dimensioned to receive the plug means 30 therein, as described below.

In the illustrated embodiment, both the skirt 50 and the spring 56 are integrally formed from a suitably flexible and/or resilient plastics material. This is, however, not essential and the skirt and spring can be formed separately, from differing materials if desired, and joined as illustrated by any suitable means such as a clip or screw thread.

The apparatus 10 also comprises engagement means in the form of an end cap 60, best shown in Figure 5. The end cap takes the form of a generally cylindrical tube 60 that is open at a first end 62 thereof and closed at a second, opposite end 64 thereof by a perforated wall 66. The main body of the tube 60 has a diameter that is sized to receive, and slide over, the nozzle portion 40 of the plug means 30, while the open first end 62 of the tube 60 is flared outwardly to provide an outer diameter comparable to that of the spring 56.

A plurality of longitudinal slots 68 are circumferentially spaced around the body of the end cap 60 and extend from the flared portion of the tube to an approximate mid-point thereof. The perforated end wall 66 is slightly recessed from the second end 64 of the tube 60, and has a plurality of holes 70 formed therein arranged around a longitudinally extending spike 72. The circumferential wall of the tube 60 at the second end 64 thereof is castellated, having a plurality of circumferentially spaced notches 74 formed therein.

Use of the apparatus of Figure 2 will now be described with reference to Figures 7 and8.

In a first step, the plug means 30 is inserted into the axial bore 58 extending through the skirt 50 and spring 56. The spring 56 and/or skirt 50 may be provided with clip means in the form of radially inwardly directed protrusions (not shown) arranged to engage with corresponding recesses or apertures formed in the tube 30 when the latter is inserted to the correct depth. The clip means is arranged to releasably retain the spring 56 and skirt 50 in the desired position with respect to the plug means 30.

The apparatus may be supplied in this partially assembled form, i.e. with the plug means already correctly inserted to the correct depth, as shown in Figures 6 and 7a.

In this case, the above mentioned first step is not carried out by the user.

In a second step, the end cap 60 is slid over the free end of the plug means 30 until it abuts the end of the spring 56. As described above, the flared portion 62 of the end cap 60 is comparable in diameter to the diameter of the spring 56 so that the two abut evenly, although this is not essential. The fins 46 are arranged to cooperate with, and engage in, the slots 64 in the end cap 60 sO as to retain the end cap in position and prevent it from slipping from the end of the plug means 30.

Again, the apparatus may be supplied to the user in this partially assembled form, i.e. with the end cap in position in abutment with the spring, as shown in Figures 6 and 7a. In this case, the above mentioned second step is not carried out by the user.

In a third step, a suitable hole 80 is formed, e.g. by drilling, in the front plasterboard layer 12 of the stud wall 10. The diameter of the hole 80 is selected to correspond approximately with the diameter of the enlarged diameter portion 25 of the plug means 30.

The apparatus 20, in partially assembled form, is then inserted into the hole 80 formed in the stud wall 10, as shown in Figure 7b. As the apparatus 20 is inserted further, the leaves 54 of the skirt 50 are compressed by the perimeter of the drilled hole 80 and are folded radially inwardly from their rest position as they are drawn through the hole 80. Once inside the cavity 18 of the stud wall 10 (Figure 7c), the leaves 54 return substantially to their original rest position.

Further insertion of the apparatus 20 into the cavity 18 causes the second 64 of the end cap 60 comes into contact with the inside surface of the second or rear plasterboard layer 14 of the stud wall 10. The forwardly protruding spike 72 pierces the cellulose layer on the inside surface of the rear plasterboard layer 14 and penetrates into the plasterboard substrate until the castellated edge of the second end 64 of the end cap 60 abuts the plasterboard layer. At this point, further forward movement of the end cap is limited or substantially prevented. However, a proportion of the enlarged diameter portion 25 of the plug means 30 protruding from the hole 80 in the first plasterboard layer 12 (Figure 7d).

Continued axial force on the plug means 30 causes the spring 56 to compress, permitting further insertion of the plug means 30 through the hole 80 and into the cavity 18 whilst the end cap remains substantially fixed in position relative to the plasterboard layers 12, 14. Eventually, the tension force generated between the end cap 60 and the skirt 50 by compression of the spring 56, overcomes the retaining force of the clips fixing the skirt 50 in position relative to the plug means 30 causing the spring 56 to expand and force the skirt 50 rearwardly towards the inner surface of the first plasterboard layer 12 and into pressing engagement therewith.

In this position, best shown in Figure 7e, the plug means 30 is substantially fully inserted into the hole 80 in the first plasterboard layer 12 with the flange 31 abutting, and substantially flush with, the outer surface of the front plasterboard layer 12. In the event that the first end 34 of the plug means 30 remains protruding from the wall, further insertion may be permitted by additional compression of the spring 56. Such further compression of the spring 56 may advantageously serve again to apply tension between the skirt 50 and the end cap 60, pressing them against the inner surfaces of the first and second plasterboard layers 12, 14, respectively.

In a fourth step, the user applies, for example by injection, a suitable adhesive substance, such as a chemical adhesive or curable mortar 90, into the bore 32 of the plug means 30 through the open first end 34 (Figure 8a). The injected adhesive 90 partially fills the bore 32 but also flows out of the apertures 41 and into the skirt 50.

The leaves 54 of the skirt 50 provide a retaining effect on the adhesive to prevent it from spreading too far across the plasterboard layer surface, thereby reducing adhesive loss. Once the required amount of adhesive has been injected, there will be adhesive 90 deposited in the bore 32 and in the deployed skirt 50 (Figure 8a).

In a fifth step, the user inserts the support member 22 into the bore 32 in the plug means 30 and drives it into threaded engagement therewith by means of a suitable twist-drive tool such as a screwdriver or the like. Insertion of the support member 22 into the bore 32 hydraulically compresses the adhesive 90, causing some of the adhesive 90 in the bore 32 to be extruded through the radially spaced apertures 41, filling the skirt 50 and causing the leaves 54 to be splayed radially outwardly into a deployed position. The leaves 54 of the skirt 50 act to retain the majority of the adhesive 90 therein so that a first mass or "charge" of adhesive 90 surrounds the plug means 30 at its interface with the first plasterboard layer 12 which, when cured, securely fixes the plug means 30, and hence the apparatus, to the first plasterboard layer 12. The splaying of the leaves 54 increases the surface contact area of the adhesive with the first plasterboard layer 12 whilst reducing adhesive loss.

At a predetermined depth of insertion of the support member 22 into the bore 32, the apertures 41 become blocked by the body of the support member 22 itself. Further insertion thus causes the adhesive 90 to be extruded along the bore 32 in the nozzle portion 40, through the apertures 70 in the end wall 66 of the end cap 60 and out of the notches 74 in the castellated wall of the end cap 60.

In this manner, the end 64 of the end cap 60 in contact with the second plasterboard layer 14 is surrounded by a second mass or "charge" of adhesive which, when cured, securely fixes the end cap 60, and hence the apparatus 20, thereto.

The user continues to twist-drive the support member 22 into the bore 32 of the plug means 30 until the first end 24 thereof is substantially flush with the outer surface of the first plasterboard layer 12 and/or the flange 31 (Figure 8b). In this position, the threaded bore formed in the support member 22 is accessible for insertion of a suitable threaded fastener such as a screw or bolt.

While such a threaded fastener can be inserted into the threaded bore immediately after installation of the apparatus in the stud wall 10, it is advantageous to permit the adhesive to set or cure before doing so, to minimise disturbance to the apparatus 20.

Once the adhesive 90 is cured, the threaded fastener can be twist driven into the threaded bore for attaching an object to the wall 10. When the threaded fastener is tightened, the object is effectively clamped between the head of the threaded fastener and the driving head of the apparatus. This arrangement results in little or no damage to the plasterboard layer and further tightening of the threaded fastener simply results in a greater clamping force being applied to the object.

The cooperation between the threaded fastener and the support member 22 when fixing an object to the wall is similar to that described in UK Patent No. 2,437,303, in the name of the present applicants, the contents of which are expressly incorporated herein by reference and to which the reader is referred for further details.

Physical embodiments of the invention have proved to provide greatly enhanced load bearing performance compared with known devices. It will be appreciated that, once fully installed, the apparatus 20 bridges the cavity 18 such that it is in engagement with both the front and rear plasterboard layers 12, 14 of the wall 10 and is firmly attached thereto, at both ends, by the chemical adhesive 90.

Furthermore, the engagement of the spike 72 with the rear layer 14 of the wall 10, together with the securing effect of the adhesive 90, achieves at least two beneficial effects: Firstly, the arrangement provides a considerable resistance to the torque or moment applied to the apparatus 20 by the weight of a supported object, thereby reducing or substantially eliminating twisting or rotation of the apparatus 20 within the front plasterboard layer 12. This ensures a stronger, more reliable fixing with less damage to the plasterboard layer compared to conventional devices.

In addition, the arrangement provides a cantilever effect, permitting at least part of the load to be carried by the second plasterboard layer 14. This advantageously allows the apparatus 20 to be used for supporting significantly greater loads than conventional devices, wherein the load is carried entirely by the outer plasterboard layer 12.

By way of example, the applicants have found empirically that a 5mm threaded bar inserted into the apparatus of Figure 2 and subjected to a load perpendicular to its longitudinal axis is liable to plastically deform before failure of the plasterboard layers or the apparatus itself. This suggest greatly enhanced load bearing capability compared with existing devices. Furthermore, even with loads sufficient to cause such plastic deformation, little or no visible damage occurs to the front or rear plasterboard layers 12, 14.

The spring 28 performs several functions. For example, it permits the apparatus to be used with various depths of cavity wall 10, as determined by the maximum compression of the spring relative to its uncompressed length. In addition, the spring is able to exert a continuous tension between the end cap 60 and the skirt 50, pushing them apart into pressing engagement with the first and second plasterboard layers 12, 14 respectively. This improves the stability of the apparatus 20, particularly during injection and curing period of the adhesive 90.

While the apparatus shown in Figures 2 to 4 and described above represents a particularly advantageous embodiment of the invention, there are, nevertheless, a number of modifications or alternatives envisaged within the scope of the present invention.

For example, although the skirt 50, the spring 56 and the end cap 60 are described as being separate components, it is possible for these to be formed as a single unit.

Alternatively, or in addition, the plug means 30 may be formed integrally with one or more of the skirt 50, the spring 56 and the end cap 60.

Although the external screw thread on the support member 22 advantageously provides a key to the adhesive in the bore 32 of the plug means, it is not essential. In one embodiment of the invention, the support member 22 is non-threaded and is simply pushed into the bore 32 of the plug means 30. This still has the effect of extruding the adhesive out of the apertures 41, 70 so as to contact the inner surfaces of the front and rear wall layers. In this case, the support member may be secured in the bore 32 by means of an interference fit (friction) or by the adhesive itself once cured.

However, it is envisaged that the support member 22 itself may be unnecessary if the plug means 30 is made with suitable load bearing characteristics. In this case, the internal bore 32 may be sized to receive the threaded fastener directly, the insertion of which could be used to extrude the adhesive 90 into the skirt 50 and through the end cap 60, as described above.

The circumferentially spaced apertures, slots or ridges described above may be spaced equiangularly around the apparatus, or at any other suitable spacing.

The various components, whether separate or integral, may be formed from any suitable material, such as metals or plastics.

The adhesive substance may be selected as desired, although it is preferable to use an adhesive whose viscosity is sufficiently low to permit extrusion from the apertures by insertion of the support member whilst being sufficiently high to prevent significant loss through the apertures before the support member is inserted.

Although the apparatus 20 has been designed particularly for use with stud walls, it is equally applicable for use with other types of cavity walls, such as those having an underlying brickwork substrate layer. In this case, the end cap may be arranged to engage in a suitable hole or recess formed in the underlying substrate layer by the user.

It will be appreciated that the present invention improves upon existing plasterboard anchors by providing means for cooperating and/or engaging with the rear-most layer of a cavity wall, for example rear plasterboard layer 14 of a stud-wall or the underlying brickwork substrate layer of a dry-lined, in addition to the front (outer) plasterboard layer 12. This is in contrast with known plasterboard anchors which engage only with the outer plasterboard layer of the wall.

Engagement with the rear layer of the wall improves the load capacity of the fixing and reduces the adverse effects of twisting or bending of the apparatus within the plasterboard layer 12. As a result, damage to the plasterboard layer 12 is also reduced or substantially eliminated.

General Interpretation of Terms While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. For example, the size, shape, location or orientation of the various components can be changed as needed and/or desired.

Components that are shown directly connected or contacting each other can have intermediate structures disposed between them. The functions of one element can be performed by two, and vice versa. The structures and functions of one embodiment can be adopted in another embodiment. It is not necessary for all advantages to be present in a particular embodiment at the same time.

Each feature and/or method step recited in the appended claims or disclosed hereinabove may be taken independently or in combination with any other feature and/or method step. Multiple features and/or method steps may be combined and any and all such combinations are intended to be included within the scope of this application.

In the above description, and in the claims, the term "cavity wall" is used to refer collectively to walls of the types shown in Figures 1 and 2, and any other form of wall or structure having a first, outer layer spaced from a second, underlying layer by a gap or cavity.

Every feature and/or method step which is unique from the prior art, alone or in combination with other features and/or method steps, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

Claims

CLAIMS: 1. An apparatus for fixing an object to a wall having a first layer and a second layer spaced from the first layer by a cavity, the apparatus comprising: a support structure arranged to bridge the cavity and to cooperate with the first and second layers; and means for dispensing an adhesive substance onto internal surfaces of the first and second layers so as to secure the support structure thereto.
2. An apparatus as claimed in claim 1, wherein the support structure comprises plug means having an internal bore for receiving said adhesive substance.
3. An apparatus as claimed in claim 2, wherein the support structure comprises an end cap portion adjustably coupled to the plug means for adjusting the length of the support structure.
4. An apparatus as claimed in claim 3, wherein the end cap portion comprises an internal bore extending therethrough and arranged to slidably receive a nozzle portion of the plug means.
5. An apparatus as claimed in claim 3 or claim 4, wherein the end cap portion comprises means for engaging with the internal surface of the second layer, in use.
6. An apparatus as claimed in claim 5, wherein the means for engaging comprises a spike or other projection arranged to pierce and/or penetrate the internal surface of the second layer.
7. An apparatus as claimed in any of claims 3 to 5, wherein the end cap portion comprises at least one aperture for permitting said adhesive to be dispensed onto the internal surface of the second layer.
8. An apparatus as claimed in any of claims 2 to 7, wherein the support structure comprises skirt means, slidably mountable on the plug means and arranged to at least partly define with the internal surface of the first layer a volume for retaining and or controlling said adhesive.
9. An apparatus as claimed in claim 8, wherein the plug means comprises at least one aperture arranged to fluidly connect the internal bore to the variable volume within the skirt means so as to permit the adhesive to be dispensed onto the internal surface of the first layer.
10. An apparatus as claimed in claim 8 or claim 9, wherein the skirt means comprises a plurality of flexible and/or resilient leaves capable of adopting a plurality of positions including: a folded position, in which the skirt means can be passed through a hole formed in the first layer; and a deployed position in which the leaves are splayed or flared radially outwardly under pressure of the adhesive substance retained therein.
11. An apparatus as claimed in any of claims 8 to 10, comprising spring means disposed between the end cap portion and the skirt means and arranged to bias the end cap portion and the skirt means into pressing engagement with the internal surfaces of the first and second layers, respectively.
12. An apparatus as claimed in any of claims 2 to 11, wherein the internal bore of the plug means is arranged to receive a threaded fastener or the like.
13. An apparatus as claimed in claim 12, wherein the support structure comprises a support member adapted to be received in the internal bore of the plug means, the support member including a blind bore adapted to receive a threaded fastener or the like.
14. An apparatus as claimed in claim 13, wherein the support member is provided with an external thread for threaded engagement with the internal bore of the plug means.
15. An apparatus as claimed in claim 13 or 14, wherein the support member comprises means for cooperating with a twist-drive tool so as to permit the support member to be twist-driven into the internal bore in the plug means.
16. An apparatus as claimed in any of claims 12 to 15, wherein insertion of the threaded fastener and/or the support member into the internal bore in the plug means hydraulically extrudes the adhesive substance through the or each aperture in the end cap portion and the plug means and onto the internal surfaces of the first and second layers, respectively.
17. An apparatus as claimed in any preceding claim, wherein the support structure is formed from a plastics material.
18. An apparatus as claimed in any of claims 13 to 16, wherein the support member is formed from a generally rigid material such as a metal or plastics material.
19. An apparatus for fixing an object to a cavity wall having first and second layers spaced by a cavity, the apparatus comprising: means for engaging in a hole formed in the first layer; means for engaging or cooperating with the second layer; means for engaging with a threaded fastener; and means for dispensing an adhesive substance onto internal surfaces of the first and second layers so as to secure the support structure thereto.
20. An apparatus as described in EP2097034, the improvement comprising: means for engaging with a second layer of a cavity wall; and means for dispensing an adhesive substance onto internal surfaces of the first and second layers so as to secure the support structure thereto.
21. A method of fixing an object to a surface having a first layer and a second layer spaced from the first layer by a cavity, the method comprising: inserting a support structure into a hole in the first layer; engaging a distal end of the support structure with the second layer; and dispensing an adhesive substance onto internal surfaces of the first and second layers so as to secure the support structure thereto.
22. A method as claimed in claim 21, comprising injecting or depositing the adhesive substance into an internal bore of the support structure.
23. A method as claimed in claim 22, comprising inserting a support member into the internal bore of the support structure so as to extrude the deposited adhesive substance from the internal bore onto the internal surfaces of the first and second layers.
24. A method as claimed in claim 23, comprising inserting a threaded fastener into an internal bore of the support member and clamping the object between the support member and a head of the threaded fastener.
25. A method as claimed in any of claims 21 to 24, comprising using an apparatus as claimed in any of claims 1 to 20.
26. An apparatus or a method constructed and/or arranged as described herein with reference to accompanying Figures 2 to 4.