GB2462818A

GB2462818A - Apparatus and method for fixing to a laminated material

Info

Publication number: GB2462818A
Application number: GB0815064A
Authority: GB
Inventors: Richard Hall
Original assignee: HOLDFAST FIXINGS Ltd; SENICO Ltd
Current assignee: HOLDFAST FIXINGS Ltd; SENICO Ltd
Priority date: 2008-08-18
Filing date: 2008-08-18
Publication date: 2010-02-24
Also published as: WO2010020768A1; GB2462866A; GB2462866B; AU2009284007B2; AU2009284007A1; GB0816953D0; GB0815064D0

Abstract

A fixing 32 for a laminated material (e.g. plasterboard) comprises an elongate shaft extending from a tip to a head, the shaft having an external screw thread comprising a first thread section 33 proximate the tip and a second thread section 34 proximate the head. The first thread section 33 has a thread diameter or form that differs from a thread diameter or form of the second thread section 34 thereby to adapt the first thread section 33 to a different material. When used in a dry lined wall, the first thread section 33 may engage with the masonry in order to provide pull-out resistance. The second thread section 34 can engage with the plasterboard In order to hold the plasterboard in place. The fixing 32 can be in the form of a screw or a plug.

Description

Apparatus and method for fixing to a laminated material

FIELD OF THE INVENTION

The present invention provides an apparatus and a method for fixing to a laminated material, such as a dry-lined wall.

BACKGROUND ART

The provision of secure fixings into laminated surfaces has presented problems for some time. This has however become more acute in recent decades with the development of the dry-lined wall (hereinafter "DLW") in which a layer of plasterboard or other gypsum-based board about 12.5 mm (1/2") is glued to a masonry surface by large pads of adhesive. This leaves a cavity of around 10 mm between the plasterboard and the underlying masonry surface.

This gypsum surface is then covered with a layer of "skim" or plaster in order to provide a smooth outer surface that can be painted or otherwise decorated. A DLW has significant advantages during the constructional phase in that there is * I. very much less water to expel from the plaster coat (as opposed to a plastered wall), allowing further constructional steps to take place days or weeks earlier than would otherwise be possible.

Dry-lined walls do however present problems to the building owner after : construction. It is common to add fittings to the building, such as shelves or S.. *

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furniture units, and these must be attached to the wall using a suitable fitting.

The dry-lining layer of such a wall offers little strength against pull-out or plucking forces, but it is difficult to make a secure connection to the underlying masonry wall without causing damage to the dry lining. A wide range of fixings for plasterboard walls are currently available, none of which are especially satisfactory for heavy loads. Very little is available for a dry-lined wall.

SUMMARY OF THE INVENTION

The present invention therefore provides a fixing for a laminated material comprising an elongate shaft extending from a tip to a head, the shaft having an external engagement formations comprising a first set of formations proximate the tip and a second set of formations proximate the head, the first set of formations having an external diameter or form that differs from a external diameter or form of the second set of formations thereby to adapt the first set of formations to a different material.

This permits the first thread section to engage with the masonry wall in order to provide the necessary pull-out resistance. Meanwhile, the second thread section can engage with the plasterboard layer in order to hold it in place (and therefore protect it) and also to use the resistance to shear forces that the plasterboard is capable of providing. Thus, the first and second thread sections preferably have a combined length greater than about 20mm in length so that the first thread section can extend into the masonry.

The second set of formations can comprise a screw thread, as this tends to be especially suited to establishing and maintaining a grip in plasterboard material. The first set of formations can comprise a series of outwardly * .* ... extending projections such as ribs, flanges or a second screw thread. *

The first and second thread sections can have the same thread pitch so as : to pass smoothly through the two layers without disturbing their relative *. position. Alternatively, such as for use in other laminate situations, the first : thread section can have a thread pitch greater than that of the second thread *.S *

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*SSS*; * * section. This will tend to draw the outer layer more firmly toward the underlying layer.

Such a fixing can be (for example) in the form of a screw. Typically, this will have a head that is wider than the shaft. This can be adapted to be recessed when fitted, which will be particularly useful in securing a plasterboard sheet to a substrate, for example.

Alternatively, the fixing can be in the form of a plug with suitable external threaded sections as defined above to secure the plug in place prior to screwing into the plug. This can include a head which comprises a flange extending outwardly of the shaft to prevent the plug from entering too far into the laminate structure. Such a flange is preferably circumferential.

A special tool may be provided for screwing the fixing in to place. This is particularly useful if the fixing is made of plastic or Nylon, as conventional drive forms such as posidrive screws, or Allen key drives, may have difficulty in transmitting enough torque to the fixing. As the diameter of the fixing can not be conveniently extended, the depth of the engagement formation between the fixing and the tool can be extended. For the purpose of rotating and driving the tool, the tool may either have a handle, or a posidrive or Allen key form that can be driven by a screwdriver (either manual or electric). Further, the tool may have an external form that substantially matches the internal form of the entire fixing along its full depth. In this way, the tool provides support for the fixing as it is put into place. It will be appreciated that this is a benefit whether the fixing is screwed, or driven into place, as plastic fixings are vulnerable and relatively delicate during this operation. * *

Thus the external form of the tool can comprise a round pin of a diameter **L* to match the internal form of the fixing, and a triangular prism form to match *,*, the internal form of the head region of the fixing, and (optionally) a hexagonal * * or other non rotationally symmetric form which will extend outside the fixing for * attachment to a source of torque. * ** * U

The fixing defined above can be of metal, plastic or Nylon. *

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described by way of example, with reference to the accompanying figures in which; Fig 1 shows a uniform material with pilot hole for fixing; Fig 2 shows a material covered with laminate of different material, with pilot hole; Fig 3 shows a fixing to thread forming single material; Fig 4 shows a fixing to laminated material; Fig 5 shows a uniform material with oversize pilot hole for fixing; Fig 6 shows a uniform material with fixing plug; Fig 7 shows a known fixing to non-thread forming single material; Fig 8 shows a known fixing to soft thread forming material such as plasterboard; Fig 9 shows an improved fixing to thread forming laminar materials; Fig 10 shows an improved fixing to attach threadable laminar material to different threadable material; Fig 11 shows an improved fixing to plasterboard laminar on wood; Fig 12 shows an improved fixing to attach plasterboard to wood with no screw head; * *S Fig 13 shows a plasterboard laminate fixed to masonry wall, with small cavity between (a so-called Dry Lined wall, or DLW); * * S * Fig 14 shows a combination fixing suitable for use as a DLW fixing.;

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Fig 15 shows a combination fixing inserted into a DLW * S. * * * S.. *

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* SSS*S * S Fig 16 shows the completed fixing using a combination fixing in a DLW;

DETAILED DESCRIPTION OF THE EMBODIMENTS

Fig 1 shows a pilot hole 1 for a fixing, drilled into uniform material 2.

Fig 2 shows a pilot hole 1 for a fixing, drilled into a material 3 covered with a lamina 2 of a different material.

In Fig 3, a conventional screw 5 is used to attach a bracket 4 to material 2. The screw can be chosen to suit the material. For example, if material 2 is a metal a self-tapping screw may be used. If material 2 is wood, a wood screw can be used. Many different types of screw have been designed, optimised for different materials.

In Fig 4, a conventional screw 5 is used to attach bracket 4 to a laminate made of material 3 and material 2. The choice of screw 5 is a compromise between the requirements for material 3 and the requirements for material 2.

When fixing to a non-threadable material such as brick or concrete, a known two part fixing is required as shown in Fig 7. In this case, an oversize pilot hole 7 (shown in figure 5) is drilled, and an expandable plug 8 (known as a "rawiplug") shown in fig. 6 is first inserted into hole 7. Bracket 4 can then be attached using screw 9 that screws into expandable plug 8.

Figure 8 shows a known specialised plasterboard fixing 11 screwed into plasterboard material 10. Deeper serrations are provided on the fixing 11 to make a satisfactory grip in the plasterboard, in view of the greater friability of the board material. A bracket 4 may be attached by screwing a self-tapping screw 12 into fixing 11. * ** * * * * **

Figure 9 shows a fixing screw 13 improved according to the current *�..

invention, so that thread form 14 is optimised for material 3, and thread form 15 *S.S : is optimised for material 2. For example, for softwood laminated onto r aluminium, thread form 14 is a self-tapping thread form, and thread form 15 is a * ** woodscrew thread form. It should be noted that by optimising the fixing 13 for * * * *** *

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***,.S * * the two different materials, superior tensile and shear load performance is achieved for the fixing. In this example, most of the tensile load capability is derived from the thread form 14 in the aluminium, and most of the shear load capability is derived from the thread form 15 in the wood (as the wood is close to the bracket 4). It should be noted that to avoid creating any force that would pull the laminar 2 away from the material 3 the pitch of the two threadforms 14 and 15 should be identical (even though the thread diameter and profile may be different).

Figure 11 shows another embodiment of the current invention where fixing 20 is optimised for a wood and plasterboard lamina. Fixing 20 consists of wood screw threadform 21 and plasterboard threadform 22. Both threadforms have the same pitch, to avoid compression or extension of the plasterboard.

Bracket 4 can be attached to the fixing 22 using self tapping screw 23.

Figure 10 shows another embodiment of the current invention where fixing 16 is used to attach wood 2 to aluminium 3 without a protruding screwhead. In this case, threadform 17 is a metal self-tapping form and 18 is a wood screw threadform. In this case, the pitch of threadform 18 is marginally less than the pitch of threadform 17 so that when the fixing 16 is screwed into the materials (using posidrive form 19) the wood 2 is pulled tightly against aluminium 3.

Figure 12 shows another embodiment of the current invention where fixing 24 is used to attach plasterboard 2 to wood 3. In this case, threadform 25 is a wood screw form, threadform 26 is optimised for plasterboard, and the pitch of threadform 26 is slightly less than the pitch of threadform 25 so that the plasterboard is pulled tightly to the wood without the need for an external screw * ** I. * * * ea * **S* Referring to figure 13, masonry 3 is covered in plasterboard material 2 *:::: which is fixed to the masonry using adhesive 27. A hole 7 is shown drilled ready *:. for a fixing. Such a combination of materials is known as a "dry lined wall" (DLW), and is a relatively common alternative to conventional plastering of * * * * *** I * * S * masonry. It should be noted that a cavity of variable width is usually found between the plasterboard and the masonry. When applying a fixing to such a combination of materials, the very different characteristics of the materials needs to be taken into account.

Figure 14, 15 and 16 show a preferred embodiment of the invention to provide a superior DLW fixing.

Fig 14 shows a combination fixing, 32, where the fixing form is optimised along its length, for the two different materials that make up a DLW. In particular Combination fixing 32 has an expandable section where it will be adjacent to the masonry 3 and a non-expandable section where it will be adjacent to the plasterboard 2. In addition, a compliant threaded section 33 adjacent to the masonry aids the insertion of the combination fixing and a threadform 34 is optimised for fixing to plasterboard. The pitch of both threadforms is the same, so that when the combination fixing is screwed into the hole, the plasterboard is not driven either to, or away from, the masonry, hence avoiding cracking and damage to the plasterboard.

Figure 15 shows combination fixing, 32, located in the hole,7, that has been prepared in the DLW.

To complete the fixing as shown in figure 16, screw 35 is driven through bracket 4 and into combination fixing 32. The screw 35 expands the combination fixing 32 in the region of the masonry only. This fixing achieves high tensile strength from the masonry section of the fixing, and high shear load capability from the plasterboard portion of the fixing (plasterboard is quite adequate for most applications in shear load, but is weak in "plucking" loads). Of course, the * *. masonry section also provides high shear load capability, but it is particular important in the fixing that shear load capability is located close to the load, represented by the backet,4, as a typical screw,35, while being very strong in :, tension, is relatively compliant when side loads are imparted if the screw is not ** * *:. well supported up to the head. * S. * . S *.S S

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The combination fixing, 32, has a relatively complex internal form, as shown in figure 14. At the head end, in the region of threadform 34, the form is a deep triangular hole, extending for typically 10 mm. In the region of threadform 33, the internal form is a small diameter circular hole, so that when the screw, 35, is inserted, this section will expand and grip the masonry. As already mentioned, this section is also slotted to facilitate this expansion. The hole between these two regions is larger diameter, such that the combination plug is gripped by the screw, 35, but is not forced to expand.

The combination fixing 32 may optionally be driven into place using a special tool that has an external form that matches the internal form of the combination fixing 32. Thus the external form is a round pin, of substantially identical diameter to match the internal form of the combination fixing, and a triangular prism form to match the internal form of the combination fixing 32 in the head region. The tool then has a hexagonal or other non rotationally symmetric form which will extend outside the fixing and can be used for fitting to an electric screwdriver. It will be appreciated that the tool not only provides rotational torque to the combination plug via the triangular form, but also longitudinal support, along the length of the combination fixing, with the round pin form. In particular, the very tip of the combination fixing 32 is supported by the tool. This crucially prevents the expanding section of the combination fixing 32 expanding through axial compression loads while the combination fixing 32 is driven into place.

It wJJJ of course be understood that many variations may be made to the above-described embodiment without departing from the scope of the present invention. * ** * . * * * *** * * * *S*. * * *

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Claims

CLAIMS1. A fixing for a laminated material comprising an elongate shaft extending from a tip to a head, the shaft having an external engagement formations comprising a first set of formations proximate the tip and a second set of formations proximate the head, the first set of formations having an external diameter or form that differs from an external diameter or form of the second set of formations thereby to adapt the first set of formations to a different material.
2. A fixing according to claim 1 in which the first and second set of formations have a combined length greater than 20mm in length.
3. A fixing according to claim 1 or claim 2 in which the second set of formations comprise a screw thread
4. A fixing according to any one of the preceding claims in which the first set of formations comprise a series of outwardly extending projections.
5. A fixing according to claim 2 in which the outwardly extending projections comprise a screw thread.
6. A fixing according to claim 5 as dependent on claim 3 in which the screw threads of the first and second set of formations have the same thread pitch.
7. A fixing according to claim 5 as dependent on claim 3 in which the screw thread of the first set of formations has a thread pitch greater than that of the second set of formations.
8. A fixing according to any one of the preceding claims in the form of a * ** screw. * * . * S. S...
9. A fixing according to claim 8 in which the head of the screw form is wider than the shaft.*:.
10. A fixing according to claim 8 or claim 9 in which the head is adapted to be recessed when fitted. * .. * . S *** .S*SS... S *11. A fixing according to any one of claims 1 to 7 in the form of a plug.12. A fixing according to claim 11 in which the head comprises a flange extending outwardly of the shaft.13. A fixing according to claim 12 in which the flange is circumferential.14. A fixing according to any one of the preceding claims being of metal.15. A fixing according to any one of claims 11 to 13 being of a plastics material.16. A fixing according to any one of claims 11 to 13 being of Nylon.17. A fixing according to any one of the preceding claims having an internal bore.18. A fixing according to claim 17 in which the internal bore has a circular section proximate the first set of formations, and a proximate the second set of formations.19. A fixing according to claim 18 in combination with an insertion tool, the tool comprising a round pin of a diameter to match the internal form of the fixing proximate a first set of formations, and a prismatic section to match the internal form of the head region proximate the second set of formations.20. A fixing according to claim 19 in which the prismatic section is in the form of a triangular prism.21. A fixing according to claim 18 or claim 19 in which the tool further comprises a non rotationally symmetric form extending from the prismatic **0 section to lie outside the fixing, for attachment to a source of torque. * a.* 22. A fixing according to claim 21 in which the non rotationally symmetric form is hexagonal in section. **ia * S S 0 *:. 23. A fixing substantially as herein described with reference to and/or as illustrated in the accompanying figures. **S. S *