GB2622280A

GB2622280A - Membrane anchoring device

Info

Publication number: GB2622280A
Application number: GB2213303.7A
Authority: GB
Inventors: James Link Matthew
Original assignee: Valro Manufacturing Ltd
Current assignee: Valro Manufacturing Ltd
Priority date: 2022-09-12
Filing date: 2022-09-12
Publication date: 2024-03-13
Also published as: WO2024056994A1; GB202213303D0

Abstract

An anchoring device 100 for attaching a membrane to a surface comprises a rigid bonding plate 105 having an outer rim 125, and a pliable fixing plate 110 secured beneath the bonding plate. The pliable fixing plate allows for attachment of the anchor to uneven surfaces. A hole 130 in the bonding plate gives access to the fixing plate for a fastener. The upper surface of the bonding plate has a bonding surface 135 coated in an adhesive. The fixing plate may be secured to the bonding plate at the outer rim, with the bonding plate folded over an end 145 of the fixing plate. The bonding surface may comprise a raised portion of the upper surface. The adhesive may be heat activated by inductive heating. The bonding plate may be formed from electrically conductive material such as steel. The fixing plate may be formed from non-electrically conductive material such as polyethylene. The bonding plate may be circular and the fixing plate may comprise an aperture 150 for receiving the fastener.

Description

MEMBRANE ANCHORING DEVICE BACKGROUND OF THE INVENTION

[0001] This invention relates to a device for securing a membrane to a surface.

[0002] A range of construction tasks involve the attachment of a waterproof membrane, such as a plastic or rubber sheet, to a surface. For example, a waterproof membrane may cover the roof of a building, or line the interior of a swimming pool or tunnel. The membrane must be secured to the surface without puncturing it.

[0003] One solution to this problem is described in U56640511. Steel anchor plates, having a flat top surface pre-coated with a heat activated adhesive, are screwed to a roof or other surface. The waterproof membrane is then laid over the roof and the anchor plates. An electromagnetic induction heater is used to heat each anchor plate in turn, which activates the adhesive and causes the membrane to adhere to the plates.

[0004] The plate described in US6640511 has a wide, flat countersink for accommodating the head of the fixing screw. The wide countersink has the advantage of being slightly flexible. When the plate is being secured to either a slightly uneven or slightly compressible surface, overdriving the screw causes the countersink to flex slightly rather than deforming the whole plate. In particular, the top surface of the plate is not deformed and remains substantially flat to ensure good contact between the top surface and the membrane, which ensures a good bond when the adhesive is activated.

[0005] In another arrangement of US6640511, a plastic insert is secured within a central aperture in the metal plate. The plastic insert has a central hole for receiving a screw and ensures that the force of a slightly overdriven screw is not transferred to the top surface, reducing distortion of the flat bonding area.

[0006] Although the anchor plate described above has some tolerance to uneven surfaces, it is not suitable for attaching to a highly uneven surface such as rough rock or shotcrete. In such circumstances, overdriving the screw will cause the top surface to bend significantly, compromising the bond that can be achieved.

[0007] A device for fastening plastic panels or a plastic sheet to a concrete surface is described in EP2806083. The fastening device is formed from a thermoplastic material such as polyethylene and has a flat upper surface. The upper surface has an induction welding element made of an electrically conductive material embedded into it. The device is secured to the surface by passing a screw through a central hole. The plastic sheet or panel is then attached to the device by induction welding.

[0008] An improved anchoring device that is suitable for attachment to an uneven surface is desirable.

SUMMARY OF THE INVENTION

[0009] According to the invention, there is provided an anchoring device for attaching a membrane to a structure, comprising: a rigid bonding plate having an outer rim, an upper surface, a lower surface, and a hole extending between the upper surface and the lower surface, at least a portion of the upper surface comprising a bonding surface that is substantially flat and is coated with an adhesive for attaching a membrane to the bonding plate in use; and a fixing plate that is more pliable than the bonding plate and is positioned below the lower surface of the bonding plate and secured to the bonding plate, the fixing plate being accessible through the hole in the bonding plate to enable a fastener to pass freely through the hole and to be received by the fixing plate in order to attach the fixing plate to a structure in use. In use, the relatively pliable fixing plate deforms under the force of driving a fastener through the fixing plate in preference to the relatively rigid bonding plate. Consequently, the bonding plate and, in particular, the substantially flat bonding surface are not deformed by the driving force which would compromise the bond between the membrane and the bonding surface.

[0010] The fixing plate may be secured to the bonding plate at or near the outer rim. This maximises the size of the fixing plate to ensure the maximum amount of potential deformation.

[0011] The outer rim of the bonding plate may be folded over an outer edge of the fixing plate to secure the fixing plate to the bonding plate. This ensures a strong physical connection between the fixing plate and the bonding plate so that the fixing plate is not dislodged by the driving force of a fastener or, after installation on a wall or ceiling, by the weight of an attached membrane.

[0012] The bonding surface may comprise a raised or elevated portion of the upper surface. Advantageously, this helps ensure that the bonding surface and overlaying membrane make a good contact as well as providing structural rigidity to the bonding plate. In embodiments where the adhesive is a heat-activated adhesive and the bonding plate is heated (e.g. by inductive heating), raising the bonding surface also enables the heat to be targeted on the desired area.

[0013] The bonding plate may be formed from steel. Steel is a strong, malleable material that can readily be formed into a substantially rigid structure as well as being suitable for inductive heating.

[0014] The fixing plate may be formed from a plastics material such as polyethylene. Polyethylene and other suitable plastics materials are pliable but capable of supporting a fastener. Also, in embodiments where inductive heating is used to bond the membrane to the anchoring device, a plastics material fixing plate is not heated by the induction field.

[0015] The bonding plate may be circular, having an annular portion comprising the bonding surface and a centrally located circular hole. A circular bonding plate is convenient to use and is heated evenly in an induction field.

[0016] An outer edge of the bonding plate may be folded downwardly and inwardly to form a smooth outer rim without exposed sharp edges. A smooth outer rim is safer to use and less likely to tear or cut an overlaying membrane.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Embodiments of the invention and a description of various preferred, alternative and optional features to aid understanding of the invention will now be described by way of an example only and with reference to the accompanying drawings in which: [0018] Figure 1 illustrates an anchoring device embodying the present invention; [0019] Figure 2 is a view of the anchoring device from below; [0020] Figure 3 is a cross-sectional view through the centre of the anchoring device; and [0021] Figure 4 is a cross-sectional illustration of the anchoring device in use, fastened to an uneven concrete surface;

DETAILED DESCRIPTION OF THE INVENTION

[0022] As illustrated in the figures, a membrane anchoring device 100 comprises a bonding plate 105 and a fixing plate 110.

[0023] The bonding plate 105 is in the shape of an annular disc having an upper surface 115, a lower surface 120, an outer rim 125 and a centrally located circular hole 130. An annular portion of the bonding plate between the outer rim 125 and central hole 130 is elevated to provide a flat bonding surface 135 on the upper surface 115. An outer edge of the bonding plate is bent downwardly, away from the upper surface 115, to create the outer rim 125.

This provides a circular base 140 around the periphery of the anchoring device 100 so that when the anchoring device 100 is placed on a level, horizontal surface, the bonding surface 135 is also horizontal. The bonding surface 135 is coated with a heat-activated adhesive such as a hot-melt adhesive or other suitable thermoplastic and the bonding plate 105 is made from metal or another material suitable for inductive heating.

[0024] The fixing plate 110 is also in the shape of an annular disc, having an outer edge 145 and a centrally located fastener hole 150. The fixing plate 110 is positioned next to the lower surface 120 of the bonding plate 105 and is secured to the bonding plate by folding the bonding plate's outer rim 125 inwardly around and under the outer edge 145 of the fixing plate 110. Folding the outer rim 125 inwardly also hides potentially sharp edges of the bonding plate 105 that could be a safety hazard or could tear an overlaying membrane. The outer edge 145 is therefore pushed into contact with the lower surface 120 of the bonding plate 105 near its outer rim 125. Away from this point of contact, towards the centre of the fixing plate 110, the bonding plate 105 and fixing plate 110 are shaped to space the fixing plate 110 away from the lower surface 120 of the bonding plate 105. In particular, there is a gap between the fixing plate 110 and the portion of the lower surface 120 of the bonding plate 105 underneath the bonding surface 135. The fixing plate 110 preferably does not protrude below the bottom of the circular base 140 on the bonding plate 105, however.

[0025] The fastener hole 150 in the fixing plate 110 is accessible through the central hole 130 in the bonding plate 105. The hole 130 is sized to enable a fastener such as a screw or nail, optionally with a suitable washer, as well as the head of a driving tool, such as a drill or nail-gun, to pass through freely. The fixing plate 110 is made from a plastics material or other non-electrically conductive material that is not significantly heated in the presence of a changing electromagnetic field.

[0026] In use, as illustrated in Figure 4, the anchoring device 100 is used to secure a membrane 200 to a surface 300. A fastener 155 is passed through the central hole 130 in the bonding plate 105, is received by the fastener hole 150 in the fixing plate 110, and is driven into the surface 300 to fasten the anchoring device 100 to the surface 300 via the fixing plate 110. Next, the membrane 200 is placed over the anchoring device 100 in contact with the bonding surface 135. An induction heater is pressed against the membrane 200 over the bonding surface 135 and used to heat the bonding plate 105, which activates the heat-activated adhesive to bond the membrane 200 to the anchoring device 100 via the bonding plate 105.

[0027] The bonding plate 105 is sufficiently rigid that is does not deform in typical use. In particular, it is undesirable for the flat bonding surface 135 to deform since this would compromise the bond that is achievable between the bonding surface 135 and the membrane 200. One typical use of the anchoring device 100 is in securing a membrane to a horizontal surface such as a floor or the top of a roof. Once fastened to the horizontal surface, the anchoring device 100 might be stepped on so must be sufficiently rigid not to deform, or at least to only deform slightly and elastically, under a person's weight.

[0028] Sufficient rigidity of the bonding plate 105 is ensured by both choice of material and the shape of the bonding plate. One suitable material is sheet steel which is both strong and malleable, enabling it to be formed into a desired shape, as well as being suitable for inductive heating. Other metals may be used, or the bonding plate 105 may be formed from a suitable non-electrically conductive material, such as a stiff plastics material, embedded with or otherwise combined with metallic granules or a wire mesh to enable inductive heating. Structurally, elevating the bonding surface 135 increases the resistance of the bonding surface 135 to deformation. The downwardly extending outer rim 125 also increases the rigidity of the bonding plate 105.

[0029] Even with the above qualities, the bonding plate 105 may be deformed by the force of driving a fastener through the anchoring device 100, particularly when the underlying surface 300 is very uneven. Some applications may require the use of a nail gun or other tool producing very high driving forces to be able to penetrate the surface 300. The fixing plate 110 is therefore made from a material that is relatively pliable compared to the bonding plate 105 such that the fixing plate 110 deforms when subjected to high driving forces rather than the bonding plate 105. This prevents the bonding surface 135 from being compromised.

[0030] Suitable materials for the fixing plate 110 include polyethylene and similar plastics materials. Polyethylene is sufficiently stiff and strong to support the fastener 155 so that the anchoring device 100 can be securely fastened to a surface 300. It is also sufficiently pliable that it deforms rather than breaks under a sudden large driving force. It is also more pliable than steel or other suitable materials for the bonding plate 105 so that it deforms in preference to the bonding plate 105 when subjected to such driving forces.

[0031] The region near the centre of the fixing plate 110 is slightly thicker than the region closer its outer edge 145 to help ensure that the outermost region of the fixing plate flexes and deforms in preference to the central region which is supporting the fastener 155. Under a strong, sudden driving force, the pliable fixing plate 110 will initially flex near its outer edge where the outer rim 125 of the bonding plate 105 is folded around it. This strong mechanical connection between the fixing plate 110 and the bonding plate 105 helps ensure that the fixing plate 110 is not detached by a strong driving force. If the surface 300 is particularly uneven, the fixing plate 110 may need to deform further and will preferentially stretch in the thinner region between the outer edge and the central region.

[0032] One potential disadvantage of an anchoring device 100 formed from a metal bonding plate 105 and a plastics material fixing plate 110 is that the fixing plate 110 may be heat-damaged when the bonding plate 105 is inductively heated. If the fixing plate 110 is sufficiently damaged, it may not be able to secure the anchoring device 100 to a surface 300. This problem is avoided in the described embodiments of the present invention for at least the following reasons.

[0033] The electromagnetic fields used for induction heating typically do not penetrate a significant distance. Elevating the bonding surface 135 helps ensure that the desired area is sufficiently heated to create a good bond, but also ensures that the parts of the bonding plate 105 that are in contact with the fixing plate 110 are more distant from the heating tool and are therefore not raised to as high a temperature. There is also an insulating air gap between the lower surface 120 of the bonding plate 105 and the fixing plate 110 in the region of the bonding surface 135. The outer rim 125 of the bonding plate also extends downwards, away from the elevated bonding surface 135, before folding over and around the fixing plate's 110 outer edge 145 to space this point of connection as far from the heat source as possible.

[0034] Additionally, the structural stiffening qualities described above, and the provision of a relatively pliable fixing plate 110 mean that the bonding plate 105 can be formed from a thin sheet, and thinner than the anchor plates described in US6640511, for example. This ensures that the bonding plate 105 heats up quickly in an electromagnetic field, avoiding the need to put more heating energy into it for the bonding surface 135 to reach the desired temperature. The thin bonding plate also conducts heat more slowly and cools down more quickly, protecting the fixing plate 110 from heat damage.

[0035] The anchoring device 100 is typically approximately 8cm in diameter with a height of approximately 1cm. When formed from sheet steel, the steel is typically 0.5mm thick. The central hole 130 in the bonding plate 105 is typically approximately 3cm in diameter to enable a fastener 155, optional washer and a driving tool to pass freely through it. Other shapes and sizes of anchoring device are of course possible depending upon the fabrication materials and the environment in which the device is to be used.

[0036] For example, the illustrated anchoring device 100 is advantageously circular with an annular bonding surface 135 since this does not require any special directional alignment and since induction coils are generally circular. It also avoids weak points in the bonding surface 135 that might deform under stress. Nevertheless, the anchoring device 100 may have any other outline, and the bonding surface may be any other suitable shape such as oval, square, and so on, if desired. The hole 130 in the bonding plate 105 and the fastener hole 150 in the fixing plate 110 also need not be circular, and need not be centrally located if an offset is desired. Indeed, the fixing plate 105 need not have a fastener hole 150 at all and the end user can simply drill their own hole or drive a fastener 155 through it. In this case, the centre, or another suitable location, may be marked on the fixing plate 105 as a guide.

[0037] At least the bonding surface 135 of the bonding plate 105 is coated with a heat-activated adhesive. Typically, however, the bonding plate 105 is formed by stamping it from a flat sheet of steel or other suitable material, the flat sheet having one surface coated with adhesive. Thus, the whole upper surface 115 and outer rim 135 of the bonding plate 105 are typically coated with adhesive. Coating the whole upper surface 115 may also be advantageous in preventing the overlying membrane from coming into direct contact with the metal of the bonding plate 105. In other manufacturing processes it may be easier or desirable to simply coat the whole exterior of the bonding plate 105 with adhesive.

[0038] Suitable heat-activated adhesives include thermoplastics and hot-melt glue, although any substance that can coat the bonding plate 105 and create a bond with an overlying membrane on being heated could be used. The bond may be created when the adhesive melts and re-hardens or via a chemical change, for example.

[0039] Although embodiments of the present invention are particularly suitable for inductive heating to activate a heat-activated adhesive, this is not essential. Other suitable adhesives that can be added to the bonding surface 135 during manufacture or otherwise prior to installation include pressure sensitive adhesives or a double-sided adhesive tape. The adhesive may be protected by a film that is peeled off before laying on the membrane 200. A drying adhesive, reactive adhesive, or any other suitable adhesive or glue may also be applied after fixing the anchoring device 100 to the surface 300, and before laying on the membrane 200. The choice of adhesive may also depend upon the end use. For example, it may be desirable for the membrane to be removable with sufficient force. This may be to ensure that the bond between the membrane 200 and the anchoring device 100 fails before either the membrane 200 tears or the fixing between the anchoring device 100 and the surface 300 fails.

[0040] The connection between the bonding plate 105 and the fixing plate 110 is advantageously achieved by folding the entire outer rim 135 of the bonding plate 110 around the entire outer edge 145 of the fixing plate 110 to provide a strong, mechanical fixing. However, in some applications it may be possible to secure the two components by folding or crimping only a portion of the bonding plate's 105 outer rim 135 around the fixing plate 110. Other connections are possible, including the use of adhesives or welding the bonding plate 105 and fixing plate 110 together, and different techniques may be used in combination if desired.

Claims

CLAIMS: 1. An anchoring device for attaching a membrane to a structure, comprising: a rigid bonding plate having an outer rim, an upper surface, a lower surface, and a hole extending between the upper surface and the lower surface, at least a portion of the upper surface comprising a bonding surface that is substantially flat and is coated with an adhesive for attaching a membrane to the bonding plate in use; and a fixing plate that is more pliable than the bonding plate and is positioned below the lower surface of the bonding plate and secured to the bonding plate, the fixing plate being accessible through the hole in the bonding plate to enable a fastener to pass freely through the hole and to be received by the fixing plate in order to attach the fixing plate to a structure in use.
2. The anchoring device of claim 1 wherein the fixing plate is secured to the bonding plate at or near the outer rim.
3. The anchoring device of claim 1 or claim 2 wherein the outer rim of the bonding plate is folded over an outer edge of the fixing plate to secure the fixing plate to the bonding plate.
4. The anchoring device of any preceding claim wherein the outer rim of 20 the bonding plate extends below the fixing plate to provide a base for resting the anchoring device on a structure.
5. The anchoring device of any preceding claim wherein the bonding surface comprises a raised portion of the upper surface.
6. The anchoring device of any preceding claim wherein the adhesive is a heat-activated adhesive and the bonding plate is suitable for inductive heating.
7. The anchoring device of any preceding claim wherein the bonding plate is formed from an electrically conductive material.
8. The anchoring device of any preceding claim wherein the bonding plate is formed from steel.
9. The anchoring device of any preceding claim wherein the fixing plate is formed from a non-electrically conductive material
10. The anchoring device of any preceding claim wherein the fixing plate is 10 formed from a plastics material.
11. The anchoring device of any preceding claim wherein the fixing plate is formed from polyethylene.
12. The anchoring device of any preceding claim wherein the bonding plate is circular and has an annular portion comprising the bonding surface, and the hole is a centrally located circular hole.
13. The anchoring device of any preceding claim wherein the fixing plate has a fastener hole to receive a fastener in use.
14. The anchoring device of any preceding claim wherein an outer edge of the bonding plate is folded downwardly and inwardly to form a smooth outer 20 rim without exposed sharp edges.