Patent Description:
Wall fixings and in particular plasterboard fixings are well known in the art. The general intention is to allow a fastener such as a screw to be attached to a wall. Generally, walls are constructed from materials which are not well suited to engagement by a screw thread. For example, plasterboard is typically quite thin (in the order of <NUM> - <NUM> thick) and is constructed from a material of low density. Although screws can be driven into plasterboard, they loosen quickly and are generally incapable of holding significant shear loads (say from10kg / 100N).

One solution is to use wall plugs. These are inexpensive, single-piece plastic fixings which are inserted into pre-drilled holes in the plasterboard. They have a central hollow body and resilient arms which deform against the hollow body when passing through the hole. Once through, the arms resile and prevent the wall plug from being pulled through the hole. The insertion of a screw into the body further stiffens the plug, and keeps the arms in an extended position.

Wall plugs are inexpensive, but not very strong and prone to failure at high loads.

Further solutions have been proposed for handling higher loads.

<CIT> proposes a fixing device having a body with an aperture for receiving an anchor of fastener, and a passage spaced from the aperture having a rotating shaft therein. A retaining means is disposed on the shaft, the retaining means being rotatable from a retracted position in which the fixing device can be inserted into / removed from the hole, and an extended position in which the fixing device prevents pull-out. Two or more such retaining means are typically provided.

<CIT> provides a similar device, but the retaining means can pivot on the shafts. Otherwise, the function is similar.

<CIT> provides a similar device with a moveable over-insertion stop.

In each of these devices, the retaining means needs to be actuated before the fastener is inserted-there is a two-step operation which is time consuming if many such devices need to be installed. It is also difficult to verify that the retaining means have been properly deployed.

One feature that each of these prior art devices has in common is that the retaining means are pivotable about axes generally perpendicular to the wall, and parallel to the fastener aperture. What is means is that the pull-out force tends to place a high degree of stress on the area where the retaining means is joined to the shaft (regardless of whether this is a solid join or a moveable joint). Because of the aforementioned orientation of the retaining means, this means that the torque is applied about an axis normal to the axis of rotation of the retaining means. This can be a point of failure if the device is put under significant pull-out loads.

<CIT> discloses a spring toggle. <CIT> discloses a toggle fastener. <CIT> discloses a wall fastener.

It is an aim of the present invention to overcome, or at least mitigate this problem.

According to a first aspect there is provided a fixing device for attaching a fastener to a wall according to claim <NUM>.

Preferably the length-adjusting element is rotated about the axis between the first position and the second position.

Preferably the body and the length-adjusting element are attached via a male-female mating connection. More preferably the male-female mating connection comprises a male member configured to mate with a first female formation in the first position and a second female formation in the second position. More preferably the first and second female formations are different axial lengths, limiting the degree of entry of the male member in at least one of the positions.

Preferably the length-adjusting element comprises an indicator indicating the axial length dependent on the position relative to the body.

Preferably the arms are moved from the retracted position to the extended position by insertion of a fastener.

Preferably the fastener passes through the length-adjusting element.

Preferably shafts are defined on the body, and in which the arms define openings arranged to received the shafts to enable pivotable movement.

Preferably the body is constructed from at least two body parts, and in which one of the body parts defines at least one of the shafts, and in which the other of the body parts defines a bore for receiving a free end of the at least one of the shafts.

Preferably the at least two body parts are identical.

Preferably there is provided a central body part between the at least two body parts, wherein the central body part defines the fastener receiving aperture.

Preferably the body is tapered such that it becomes wider approaching an exterior side.

Preferably the body comprises arm abutments spaced apart from the pivot axes of the arms, which arm abutments are configured to abut and thereby restrict movement of each arm off its pivot axis.

Example wall fixing devices will now be described with reference to the accompanying Figures in which:.

Referring to <FIG>, a fixing device <NUM> not according to the invention comprises a body <NUM>, a first arm <NUM> and a second arm <NUM>. The body <NUM> defines a main axis X, which also represents the main axis of insertion of the device <NUM> (to be described in more detail below).

Referring to <FIG>, the body <NUM> comprises a first side body part <NUM>, a second side body part <NUM> and a central body part <NUM>.

The side body parts are identical, and as such only the first side body part <NUM> will be described here. Referring to <FIG>, the first side body part <NUM> comprises a main portion <NUM> being generally prismatic, and having a circle segment cross-section. The circle-segment cross-section has an origin O which lies on the axis X when assembled.

The main portion <NUM> has a first end face <NUM>, a second end face <NUM>, an external face <NUM> and an internal face <NUM>. The external face <NUM> defines a part-cylinder coincident with the arc s of the segment, and the internal face <NUM> lies on a chord c of the circle segment (and is therefore flat).

The main portion <NUM> has two slots <NUM>, <NUM> partway along its axial length. The slots <NUM>, <NUM> are symmetrical and generally rectangular. A central bridge <NUM> is defined between the slots such that the main portion <NUM> defines an "H" shape in plan. Because the slots <NUM>, <NUM> are not midway along the axial length of the main portion <NUM>, it has a major section <NUM> on a first side of the slots <NUM>, <NUM> and a minor section <NUM> on a second, opposite side of the slots <NUM>, <NUM>.

Extending from the internal face <NUM> of the major section <NUM>, proximate the first end face <NUM>, there are provided two spaced apart abutments <NUM>, <NUM>. Each abutment <NUM>, <NUM> is generally obround in cross-section and extends to a free end where a respective abutment face <NUM>, <NUM> is defined.

On the opposite side of one of the abutments <NUM> to the first end face <NUM>, there is provided a shaft <NUM> extending from the internal face <NUM> of the major section <NUM>. The shaft <NUM> is longer than the abutment <NUM> and is generally circular in cross-section having a free end terminating in a hemispherical tip <NUM>.

On the opposite side of the other abutment <NUM> to the first end face <NUM>, there is provided a shaft aperture <NUM> extending from the internal face <NUM> of the major section <NUM> into the main portion <NUM>. The shaft aperture <NUM> is an open bore extending to the external face <NUM>.

Also on the external face <NUM>, there is defined an anti-rotation feature in the form of a tapered rib <NUM>. The tapered rib <NUM> extends in an axial direction from the major section <NUM>, across the bridge <NUM> to the minor section <NUM> where it terminates at the second end face <NUM> of the main portion <NUM>. The tapered rib <NUM> is triangular in cross-section along its length, but tapers to become wider and taller as it extends towards the second end face <NUM>.

The central body part <NUM> is shown in <FIG>. The central body part <NUM> comprises a first portion <NUM> and a second portion <NUM>.

The first portion <NUM> is a generally cylindrical body having an end surface <NUM>, a shoulder surface <NUM> opposite the end surface <NUM> and a radially outer curved surface <NUM> joining the end and shoulder surfaces. The radially outer surface <NUM> is interrupted by first and second diametrically opposed fist radially extending recesses <NUM>, <NUM>. Each recess <NUM>, <NUM> is generally rectangular in shape, having sidewalls <NUM>, <NUM> and <NUM>, <NUM> respectively and base walls <NUM> and <NUM> respectively. and divides the end surface <NUM> into two portions 160a, 160b. At the centre of the first portion <NUM>,open to the end surface <NUM>, there is provided a hexagonal bore <NUM>, which extends in an axial direction along X.

The second portion <NUM> is generally rectangular in shape, extending from the first portion and being oriented at <NUM> degrees to the recesses <NUM>, <NUM> of the first portion <NUM>. The second portion <NUM> with the recesses <NUM>, <NUM> subdivides the shoulder surface <NUM> into four portions <NUM>, 162b, 162c, 162d. The second portion <NUM> defines an end surface <NUM>, two opposed curved side surfaces <NUM>, <NUM> (which are continuous with the radially outer surface <NUM> of the first portion <NUM>) and to flat, planar opposed side surfaces <NUM>, <NUM>. The side surfaces <NUM>, <NUM> are continuous with the base surfaces <NUM>, <NUM> of the recesses <NUM>, <NUM> respectively. A cylindrical bore <NUM> extends from the end surface <NUM> and is continuous with the hexagonal bore <NUM>.

Also on the radially outer faces of the central body part <NUM>, there are defined two diametrically opposed anti-rotation features in the form of tapered ribs <NUM>, <NUM>. The tapered ribs <NUM>, <NUM> extend in an axial direction from first portion <NUM> to the second portion <NUM>. The tapered ribs <NUM>, <NUM> are triangular in cross-section along their length, but taper to become wider and taller as they extend from the end face <NUM> of the first portion <NUM> to the end face <NUM> of the second portion <NUM>.

The arms <NUM>, <NUM> are identical, and as such only the first arm <NUM> will be described here. Referring to <FIG>, the arm <NUM> comprises a central portion <NUM>, a foot <NUM> and two bosses <NUM>, <NUM>. Each arm <NUM> is generally elongate and symmetrical about a plane of symmetry P.

The central portion <NUM> has a pivot end <NUM> and a free end <NUM>. The central portion tapers from a first thickness t1 at the pivot end <NUM> to a second lower thickness t2 at the free end <NUM>. An arm pivot axis XA is defined by a through bore <NUM> at the pivot end <NUM>. The arm pivot axis XA extends normal to the plane P. The central portion <NUM> has an outer surface <NUM> and two opposed flat, planar side surfaces <NUM>, <NUM>. The side surfaces <NUM>, <NUM> are a width w apart.

The outer surface <NUM> comprises a first curved portion <NUM> at a first radius R1 from the pivot axis XA, and a second curved portion <NUM> at a second, greater radius R2 from the pivot axis XA, thus forming a cam (as will be described below).

The foot <NUM> is generally flat, extending from the free end <NUM> of the central portion <NUM> partway towards the pivot end <NUM> and having a contact surface <NUM> being of width wf where wf > w.

Each boss <NUM>, <NUM> extends axially along XA and is generally formed as a hollow cylinder. The boss <NUM> extends from the surface <NUM>, and the boss <NUM> from the surface <NUM>.

Each of the body parts <NUM>, <NUM>, <NUM> and the arms <NUM>, <NUM> are unitary moulded components constructed from a plastics material. In this embodiment, they are constructed from the same material.

The features of the second arm <NUM> and second side body part <NUM> will be referred to using an apostrophe.

An off-the shelf nut <NUM> (<FIG>) having an hexagonal outer and a threaded inner bore is inserted into the hexagonal bore <NUM> such that it is rotationally fixed with the central body portion <NUM>.

With reference to <FIG>, the first arm <NUM> is threaded onto the shaft <NUM> of the first side body part <NUM> such that it can pivot about the axis XA. Similarly the second arm <NUM> is threaded onto the shaft <NUM>' of the second side body part <NUM> such that it can pivot about the axis XA'.

The central body part <NUM> is then positioned between the side body parts <NUM>, <NUM>. As the side body parts <NUM>, <NUM> are brought together, the tip <NUM> of the shaft <NUM> enters the facing aperture <NUM>'. Similarly, the tip <NUM>' of the shaft <NUM>' enters the facing aperture <NUM>.

As the side body parts <NUM>, <NUM> converge, the bridges <NUM>, <NUM>' enter the recesses <NUM>, <NUM>. At the same time, opposing ends of the first portion <NUM> of the central body portion <NUM> enter the slots <NUM>, <NUM>, <NUM>', <NUM>'. The body parts <NUM>, <NUM>, <NUM> therefore become interlocked together.

It will be noted with reference to <FIG> that the surfaces <NUM>, <NUM>, <NUM> of the central body part <NUM> (i.e. the body <NUM>) form a tapered cylindrical outer with the outer faces <NUM>, <NUM>' of the side body parts <NUM>, <NUM>. The cylinder increases in diameter from D1 at an internal side (where the arms <NUM>, <NUM> are located) to D2 at an external side.

The body parts <NUM>, <NUM>, <NUM> are adhered together using adhesive.

The fixing device <NUM> is used as follows.

With reference to <FIG>, an opening <NUM> is formed in a wall <NUM> (e.g. plasterboard). The opening <NUM> is of the a diameter between the smaller and larger diameters D1, D2 of the tapered cylinder of the body <NUM>. The wall <NUM> has an outwardly facing exterior side <NUM>, and an interior side <NUM>.

The arms <NUM>, <NUM> of the fixing device <NUM> are moved together into a retracted position as shown in <FIG> and <FIG>. The fixing device <NUM> is then inserted into the opening <NUM> such that the pivot axes XA, XA' are on the interior side <NUM> of the wall <NUM>.

A bolt <NUM> is provided as known in the art, but selected to have a thread matching that of the nut. The bolt has an outer thread diameter TD.

The bolt <NUM> is inserted and rotated to engage the nut <NUM>. As the nut <NUM> is captive in the central body part <NUM>, rotation of the bolt causes axial movement along axis X. The bolt <NUM> is rotated past the pivot axes XA, XA'. As it is, the cammed outer surface <NUM> of the wings causes the wings <NUM>, <NUM> to be rotated about their respective pivot axes XA, XA' from the retracted condition of <FIG> to the deployed position of <FIG>. This is a result of the second curved portion <NUM> being a second, greater radius R2 than the first curved portion <NUM> at a first radius R1 from the pivot axis XA on the outer surface <NUM>. In other words, in the retracted position the arms <NUM>, <NUM> define a passage therebetween about axis X which is less than the diameter of the bolt <NUM>. Therefore the only way the bottle <NUM> can pass is to move the arms <NUM>, <NUM> to the deployed position.

As the arms <NUM>, <NUM> move to the deployed position, the feet <NUM>, <NUM>' bear against the inner surface of the wall <NUM>. This generates a "clamping force" which is reacted by the resistance of the body <NUM> and its diameter. It will also be noted that the anti-rotation features <NUM>, <NUM>', <NUM>, <NUM> resist both rotation and axial motion (due to the taper) of the device <NUM> relative to the wall <NUM>.

Once the bolt <NUM> has been positioned as desired, and the arms <NUM>, <NUM> are fully deployed, the bolt can be used to hang and mount items on the wall <NUM>.

To remove the device, the steps can be reversed.

Referring to <FIG>, a fixing device <NUM> not according the present invention is provided comprising a body <NUM>, a first arm <NUM> and a second arm <NUM>. The body <NUM> defines a main axis X which represents the main axis of insertion of the device <NUM> (to be described in more detail below).

In this embodiment, the body <NUM> and arms <NUM>, <NUM> are constructed from bent / formed sheet material. Therefore this particular fastener is particularly well suited to construction from sheet metal, making it both strong, durable and inexpensive to manufacture.

Referring to <FIG>, an intermediate manufacturing stage of the body <NUM> is shown. <FIG> shows the body <NUM> formed into shape for assembly. The body <NUM> comprises a base portion <NUM>, first and second side panel regions <NUM>, <NUM> and first and second pivot mounting regions <NUM>, <NUM>.

The base portion <NUM> comprises a central aperture <NUM> on the main axis X.

The first and second pivot mounting regions <NUM>, <NUM> comprise apertures <NUM>, <NUM>, <NUM>, <NUM> through the thickness thereof. Each of the regions <NUM>, <NUM>, <NUM>, <NUM>, <NUM> are rectangular in shape and connected to form a "net". In <FIG> these regions are coplanar, and cut from sheet material. Moving from <FIG>, the regions <NUM>, <NUM>, <NUM>, <NUM> have been moved through <NUM> degrees to form a box-like body <NUM>. The ends of the first and second pivot mounting regions <NUM>, <NUM> project beyond the first and second side panel regions <NUM>, <NUM>, where the apertures <NUM>, <NUM>, <NUM>, <NUM> are defined. Apertures <NUM>, <NUM> are aligned on a first arm pivot axis XA, and apertures <NUM>, <NUM> are aligned on a second arm pivot axis XA'. The pivot axes XA, XA' are normal to the main axis X.

The arms <NUM>, <NUM> are identical, and as such only the arm <NUM> will be described in detail.

Referring to <FIG> an intermediate manufacturing stage of the arm <NUM> is shown. <FIG> shows the arm <NUM> formed into shape for assembly. The arm <NUM> comprises a base portion <NUM>, first and second side panel regions <NUM>, <NUM> and first and a tab <NUM>.

The first and second side panel regions <NUM>, <NUM> comprise apertures <NUM>, <NUM> through the thickness thereof. The first and second side panel regions are tapered so as to be triangular in shape extending from their widest point proximate the tab <NUM> to a free end <NUM> distal to the tab <NUM>.

Moving from <FIG>, the regions <NUM>, <NUM>, <NUM> have been moved through <NUM> degrees to form the arm <NUM>. Apertures <NUM>, <NUM> are aligned on a first arm pivot axis XA (XA' for the arm <NUM>).

The arms can therefore rotate in opposite directions from a stowed position (<FIG> and <FIG>) where they are aligned with the main axis X and fall within the axial envelope or "footprint" of the body <NUM>, and a deployed position (<FIG> and <FIG>) where they have been rotated <NUM> degrees to extend normal to the main axis X to extend from the sides of the body <NUM> in opposite directions.

Referring to <FIG>, an internally threaded member <NUM> (in this case a nut) is provided and attached (e.g. adhered or welded) to the base portion <NUM> on the interior side of the body <NUM>, such that it is aligned with the aperture <NUM>.

Each arm <NUM>, <NUM> is inserted between the projecting ends of the first and second pivot mounting regions <NUM>, <NUM> such that the apertures align. Pivot pins <NUM>, <NUM> are provided (<FIG>) on axes XA and XA' to permit rotation of the arms <NUM>, <NUM> about the axes.

With reference to <FIG>, an opening <NUM> is formed in a wall <NUM> (e.g. plasterboard). The opening <NUM> is the same shape as the body <NUM> (i.e. rectangular). The wall <NUM> has an outwardly facing exterior side <NUM>, and an interior side <NUM>.

A bolt <NUM> is provided as known in the art, but selected to have a thread matching that of the nut <NUM>. The bolt has an outer thread diameter TD.

The bolt <NUM> is inserted and rotated to engage the nut <NUM>. As the nut <NUM> is captive relative to the body <NUM>, rotation of the bolt causes axial movement along axis X. The bolt <NUM> is rotated past the pivot axes XA, XA'. As it is, the arms <NUM>, <NUM> are rotated about their respective pivot axes XA, XA' from the retracted condition of <FIG> a to the deployed position of <FIG>. In the retracted position the arms <NUM>, <NUM> define a passage therebetween about axis X which is less than the diameter of the bolt <NUM>. Therefore the only way the bolt <NUM> can pass is to move the arms <NUM>, <NUM> to the deployed position.

As the arms <NUM>, <NUM> move to the deployed position, the base portions <NUM> bear against the inner surface of the wall <NUM>. This generates a "clamping force" which is reacted by the resistance of the body <NUM> and its diameter. It will also be noted that the polygonal shape of the body <NUM> resists rotation of the device <NUM> relative to the wall <NUM>.

Referring to <FIG>, a fixing device <NUM> according to the invention comprises a body <NUM>, a first arm <NUM> and a second arm <NUM>. The body <NUM> defines a main axis X, which also represents the main axis of insertion of the device <NUM> (to be described in more detail below). The device <NUM> further comprises a length adjusting element in the form of a washer <NUM> (<FIG>).

The side body parts <NUM>, <NUM> are identical, and similar to the side body parts <NUM>, <NUM> as described with respect to the first embodiment. Therefore, they will not be described in detail here.

Each side body part comprises a the shaft <NUM> having a tip <NUM> on one side, and an aperture <NUM> on the other (like the side body parts of the first embodiment).

The central body part <NUM> is similar to the central body part <NUM> of the first embodiment. The central body part <NUM> defines an end surface <NUM>, much like the end surface <NUM> of the central body part <NUM>. A countersunk cylindrical bore <NUM> extends from the end surface <NUM> through the central body part <NUM>.

Two pairs of blind bores are provided extending from the end surface <NUM> into the central body part <NUM>. The first pair of blind bores <NUM>, <NUM> have an axial depth of LO1 (<FIG>). The second pair of blind bores <NUM>, <NUM> have an axial depth of LO2 (<FIG>) where LO2 > LO1. Each pair of bores is diametrically opposed about the axis X, and a line joining the centre of each bore in each respective pair passes through X. The first pair and second pair are a first angle A apart.

Also on the radially outer faces of the central body part <NUM>, there are defined two diametrically opposed anti-rotation features in the form of tapered ribs <NUM>, <NUM>. These are similar to the ribs <NUM>, <NUM>.

The arms <NUM>, <NUM> are identical, and similar to the arms <NUM>, <NUM>. As such they will not be described in detail here.

The washer <NUM> is a unitary component (in this embodiment moulded from a plastics material). The washer <NUM> comprises an annular body <NUM> having a first cylindrical support flange <NUM> and a second cylindrical support flange <NUM> extending therefrom. The annular body has a circular opening <NUM> at the geometric centre thereof. The second flange <NUM> is concentric with, and within the first flange <NUM> defining an annular region <NUM> therebetween. A first support shaft <NUM> and second support shaft <NUM> extend from the annular region <NUM>, being diametrically opposed about the axis X of the washer <NUM>. Each shaft <NUM>, <NUM> has a length LS.

Referring to <FIG>, the body <NUM> defines two marker notches <NUM>, <NUM> at predetermined angular positions about its periphery (note that these are not visible in <FIG>). Each notch <NUM>, <NUM> is accompanied by information <NUM>, <NUM> respectively indicating the length of the fastener LF.

Assembly is broadly similar to the first embodiment, with the exception of two differences.

Firstly, after the side body parts <NUM>, <NUM> are brought together, and the tip <NUM> of each shaft <NUM> has entered the respective facing aperture <NUM>, the shaft tips <NUM> are heated and upset (i.e. deformed to form a head) which resists any pull-out from the aperture <NUM>. This is not depicted in the figures, but the skilled addressee will be familiar with the technique from e.g. riveting.

Secondly, the device <NUM> may be used in any of three configurations. In a first configuration, the device does not utilise the washer <NUM>. It is installed per <FIG>, having an axial length of LF0 (<FIG>).

The washer <NUM> can be engaged with the shafts <NUM>, <NUM> engaged in the first pair of openings <NUM>, <NUM>. In this configuration, the washer <NUM> is able to travel until the ends of the shafts <NUM>, <NUM> abut the ends of the openings <NUM>, <NUM>. Due to the fact that LO1 < LS, the body <NUM> of the washer is offset from the rest of the device, providing an axial length LF1 > LF0.

In a third configuration, the washer <NUM> can be engaged with the shafts <NUM>, <NUM> engaged in the second pair of openings <NUM>, <NUM>. In this configuration, the washer <NUM> is able to travel until the flange <NUM> abuts the upper surface of the device body. This is because LO2 > LO1, providing an axial length LF2, where LF1 > LF2 > LF0.

Selection of the second and third configurations is enabled by liming up the notch <NUM>, <NUM> proximate the relevant information <NUM>, <NUM> (typically length in mm or inches) with the rib <NUM> (<FIG>).

The fixing device <NUM> is used as per the device <NUM>. The primary difference is that the length of the device can be set between three levels (LF0, LF1, LF2). This allows the device to be installed in a range of thickness of board without being too loose or crushing the board.

Referring to <FIG>, a fixing device <NUM> not according to the invention comprises a body <NUM>. A pair of arms are also provided (like the first arm <NUM> and the second arm <NUM> of the first embodiment) but are not shown. The body <NUM> defines a main axis X, which also represents the main axis of insertion of the device <NUM> (to be described in more detail below).

The main portion <NUM> has a first end face <NUM>, a second end face <NUM>, an external face <NUM> and an internal face <NUM>. The external face <NUM> defines a part-cylinder coincident with the arc of the segment, and the internal face <NUM> lies on a chord of the circle segment (and is therefore flat).

Referring to <FIG>, the side body part <NUM> is shown in section. The central bridge <NUM> defines a first tab <NUM> and a second tab <NUM> extending from the sidewalls thereof. Each tab defines a first shoulder <NUM>, <NUM> and a second shoulder <NUM>, <NUM> respectively.

Extending from the internal face <NUM> of the major section <NUM>, proximate the first end face <NUM>, there are provided two spaced apart abutments <NUM>, <NUM>. Each abutment <NUM>, <NUM> is generally obround in cross-section.

Extending from one of the abutments <NUM>, there is provided a shaft <NUM>. The shaft <NUM> is generally circular in cross-section having a free end terminating in a tip <NUM>.

A shaft aperture <NUM> is provided through the other abutment <NUM> extending into the main portion <NUM>. The shaft aperture <NUM> is an open bore extending to the external face <NUM>.

Also on the external face <NUM>, there is defined an anti-rotation feature in the form of a tapered rib <NUM>.

The central body part <NUM> comprises a first portion <NUM> and a second portion <NUM>.

The first portion <NUM> is a generally cylindrical body having an end surface <NUM>, a shoulder surface <NUM> opposite the end surface <NUM> and a radially outer curved surface <NUM> joining the end and shoulder surfaces. The radially outer surface <NUM> is interrupted by first and second diametrically opposed radially extending recesses <NUM>, <NUM>.

Each recess comprises a first slot <NUM> and a second slot <NUM>, facing each other in opposing walls. Each slot defines a first shoulder <NUM>, <NUM> and a second shoulder <NUM>, <NUM> respectively.

At the centre of the first portion <NUM>, open to the end surface <NUM>, there is provided a hexagonal bore <NUM>, which extends in an axial direction along X.

The second portion <NUM> is generally rectangular in shape, extending from the first portion and being oriented at <NUM> degrees to the recesses <NUM>, <NUM> of the first portion <NUM>.

Other features of the central body part are as per the first embodiment.

As with the first embodiment, an off-the shelf nut <NUM> is inserted into the hexagonal bore <NUM> such that it is rotationally fixed with the central body portion <NUM>.

The arms are mounted for rotation on the shafts <NUM>.

The central body part <NUM> is then positioned between the side body parts <NUM>, <NUM>. As the side body parts <NUM>, <NUM> are brought together, the tip <NUM> of each shaft <NUM> enters the facing aperture <NUM>.

As the side body parts <NUM>, <NUM> converge, the bridges <NUM> enter the recesses <NUM>, <NUM>. The tabs <NUM>, <NUM> push the opposing walls of the slots <NUM>, <NUM> apart until they enter the slots <NUM>, <NUM> at which point the respective side body part is "snap-fitted" into the recess to inhibit removal thereof.

This avoids the need to adhere the body parts <NUM>, <NUM>, <NUM> together.

The fifth embodiment shown in <FIG> is similar to the second embodiment inasmuch as it is constructed from folded metal components.

The body <NUM> comprises a base portion <NUM>, and first and second wings <NUM>, <NUM>.

The first and second wings <NUM>, <NUM> comprise apertures <NUM>, <NUM>, <NUM>, <NUM> through the thickness thereof. Each of the regions <NUM>, <NUM>, <NUM> are rectangular in shape and connected to form a "net". As with the second embodiment, the regions <NUM>, <NUM> are moved through <NUM> degrees to form a box-like body <NUM>.

Each wing <NUM>, <NUM> defines a tab <NUM>, <NUM>, which is defined by a V-shaped cut. Each tab <NUM>, <NUM> is triangular, and bent outwardly from the base portion <NUM> by <NUM> degrees to as to project from each wing. Each tab <NUM>, <NUM> defines a tapered edge <NUM>, <NUM> and widens towards the base portion <NUM>.

Apertures <NUM>, <NUM> are aligned on a first arm pivot axis XA, and apertures <NUM>, <NUM> are aligned on a second arm pivot axis XA'. The pivot axes XA, XA' are normal to the main axis X.

The arm <NUM> comprises a base portion <NUM>, first and second side panel regions <NUM>, <NUM> and a tab <NUM>.

The first and second side panel regions <NUM>, <NUM> comprise apertures <NUM>, <NUM> through the thickness thereof. The first and second side panel regions are rectangular in shape.

The tab <NUM> is formed into a cammed surface <NUM> at the base of the arm, the cammed surface having a variable radius from the centre of the apertures <NUM>, <NUM>.

The arms can therefore rotate in opposite directions from a stowed position where they are aligned with the main axis X and fall within the axial envelope or "footprint" of the body <NUM>, and a deployed position where they have been rotated <NUM> degrees to extend normal to the main axis X to extend from the sides of the body <NUM> in opposite directions.

Each arm <NUM>, <NUM> is inserted between the projecting ends of the first and second wings <NUM>, <NUM> such that the apertures align. Pivot pins <NUM>, <NUM> are provided on axes XA and XA' to permit rotation of the arms <NUM>, <NUM> about the axes. In a preferred embodiment, the pivot pins are non-rotatable with respect to the body <NUM> (for example, they may be attached or keyed to the body). Referring to <FIG> in particular, it can be seen that each wing <NUM>, <NUM> is U-shaped in cross-section, and that the base portion <NUM> of the 'U' is positioned away from the interior surface of the wall in-use. In other words, the free ends of the side panel regions <NUM>, <NUM> contact the interior surface of the wall. This is beneficial as will be described below.

A circular opening <NUM> is formed in a wall <NUM> (e.g. plasterboard). The wall <NUM> has an outwardly facing exterior side <NUM>, and an interior side <NUM>.

The arms <NUM>, <NUM> of the fixing device <NUM> are moved together into a retracted position as shown in <FIG> (various other parts of the device <NUM> are omitted). The fixing device <NUM> is then inserted into the opening <NUM> such that the pivot axes XA, XA' are on the interior side <NUM> of the wall <NUM>. The tapered edges of the wings <NUM>, <NUM> bear against the periphery of the opening <NUM> and also prevent pull-through of the device <NUM>.

The bolt <NUM> is inserted and rotated to engage the nut <NUM>. As the nut <NUM> is fixed to to the body <NUM>, rotation of the bolt causes axial movement along axis X. The bolt <NUM> is rotated past the pivot axes XA, XA'. As it is, the arms <NUM>, <NUM> are rotated about their respective pivot axes XA, XA' from the retracted condition of <FIG> a to the deployed position of <FIG>. In the retracted position the arms <NUM>, <NUM> define a passage therebetween about axis X which is less than the diameter of the bolt <NUM> (due to the cammed surface <NUM>). Therefore the only way the bolt <NUM> can pass is to move the arms <NUM>, <NUM> to the deployed position.

As the arms <NUM>, <NUM> move to the deployed position, they bear against the inner surface of the wall <NUM>. This generates a "clamping force" which is reacted by the resistance of the body <NUM>, and in particular the engagement of the wings <NUM>, <NUM> against the periphery of the opening <NUM>. The fact that the wings "bite" into the wall material (e.g. plasterboard) also inhibits rotation of the device <NUM>.

As discussed above, the free edges of the side panel regions <NUM>, <NUM> abut the interior side of the wall <NUM>. Referring to <FIG>, the cammed surface <NUM> is subject to a clamping force F which results in a clamping torque about XA. The force F increases rapidly when the arms <NUM>, <NUM> contact the inside of the wall <NUM>, and at that position the force F is primarily exerted through the cam on the opposite side of the axis XA to the wall <NUM>. In this embodiment, that force is reacted by the entire base portion <NUM> of the arm <NUM> which resists deformation. Comparing to <FIG>, the metal from which the tab <NUM> is constructed needs to be quite thick to resist the clamping force exerted by the screw <NUM> (see <FIG>). This problem does not occur if the arms are reversed per <FIG>.

Variations fall within the scope of the invention.

The invention may be manufactured to suit several sizes of fastener, for example M4 or M6 thread sizes.

Instead of adhered, the body parts may be secured by e.g. push or interference fit.

The parts may be constructed from different materials. The shafts <NUM>, <NUM>' in particular may be constructed from a metal material to increase the strength of the assembly.

Any axially moveable fastener can be used.

Claim 1:
A fixing device (<NUM>) for attaching a fastener to a wall, the device (<NUM>) comprising:
a body (<NUM>) having a threaded fastener-receiving aperture defined therein, the aperture defining a main axis (X) of the fixing device; and,
at least two arms (<NUM>, <NUM>) pivotably mounted to the body between:
a retracted position in which the device is insertable into an opening in a wall from a first side of the wall; and,
an extended position in which the arms bear against a second side of the wall to inhibit removal of the device from the opening;
wherein the arms are configured to be retained in the extended position by a threaded fastener inserted in the threaded fastener-receiving aperture;
a length-adjusting element (<NUM>) configured for assembly with the body, the length adjusting element having a first position in which the fixing device has a first axial length, and a second position in which the fixing device has a second axial length different to the first.