WO1997040240A1

WO1997040240A1 - Panel for roofs

Info

Publication number: WO1997040240A1
Application number: PCT/NZ1997/000046
Authority: WO
Inventors: Raymond George Owers
Original assignee: Raymond George Owers
Priority date: 1996-04-19
Filing date: 1997-04-16
Publication date: 1997-10-30
Also published as: AU2523997A

Abstract

The invention comprises a panel (100, 200, 401) suitable for weatherproofing purposes. Panels may be affixed to a roof or onto a wall in juxtaposition or, more preferably overlapping like tiles, so that any water is diverted away from the weatherproofed area when it flows downward. In appearance, each panel may simulate a matrix of tiles. These panels have been optimised in terms of the material content required to support a given load by using increased material thickness (202, 503) beneath ridges (104). One manufacture technique is attachment of supplementary material, for example steel ribs (202) attached to an aluminum sheet, then pressing the composite to create longitudinal and perhaps transverse ridges. Thus the light-weight panels can better support the weight of a person or of solid precipitation. A ligther roof need less support framework. Attachment by fasteners exposed only to shear forces is an advantage over downwards nailing of metal roofs.

Description

Panels for roofs

TECHNICAL FIELD OF THE INVENTION

This invention relates to roofing panels that may be used in place of tiles; the panels having a optimised configuration to withstand loading, as from snow, or a person walking over a roof.

BACKGROUND

Roofing tiles have existed since antiquity, and curved individual tiles have been known for a very long time. Presumably the curving process resulting in curves or corrugations confers some improvements in strength over that of a flat tile, and presumably almost all tiles having curves throw off water better by draining a surface water layer into a focused stream, and may have other advantages, such as interlocking, as well. To the inventor's knowledge, none of the curved shapes made in modern material such as in pressed steel have adequately provided for optimisation of strength of a tile while minimising the total mass of the tile. A New Zealand building standard requires a roof tile to be able to hold a 100 Kg mass, distributed over a 100 mm x 100 mm square, on any part without structural failure. Some tiles have difficulty in meeting this requirement.

It is useful to have a light weight roof. The mass of a typical concrete tile roof, for a 2,000 square metre house, may be of the order of 20 tonnes. These tiles absorb water. Steel tiles may weigh 2-4 tonnes and advertisements for steel tiled roofs point out the advantages of these lighter weights. In an earthquake, heavy roof coverings may be hazardous to occupants.

It is also useful to make economies where practical in the timber supports for a roof, such as by reducing the number of battens and reducing the loading on purlins, because timber is scarce and expensive in many countries.

OBJECT

It is an object of the present invention to provide panels for covering roofs at least partially optimised for strength versus weight, or at least to provide the public with a useful choice. STATEMENT OF INVENTION

In a first broad aspect the invention comprises a panel for covering or weatherproofing purposes comprised of a sheet material, the panel having at least a first surface and a second surface and having one or more deformations extended along at least one axis in the form of folds or ridges generally protruding from the first surface, wherein the panel is provided with additional material upon or within the second surface at the position of the extended deformations along at least one axis, so that the panel remains relatively light in weight yet is provided with increased stiffness and increased capability to withstand a load.

Generally the first surface having protruding elongated deformations or ridges is exposed to the weather although in some instances the first surface exposed to the weather is instead provided with elongated depressions or valleys.

In a related aspect the invention comprises a panel, wherein the additional material at the position of each extended deformation is comprised of one or more additional members made of a stiff material, attached to the second surface of the panel, the tile so modified being provided with increased stiffness and increased capability to withstand a load from at least the first surface in at least those portions of the tile having the thickened deformations.

In another related aspect the invention comprises a panel, wherein the additional member or members are laid down in a pattern of ribs; each rib being adjacent to an extended deformation.

In a further related aspect the invention comprises a panel, wherein the sheet material is a metal panel, reinforced with strengthening ribs made of a stiff material.

In a yet further related aspect the invention comprises a panel, wherein the sheet material is a panel made of a plastics material, reinforced with strengthening ribs made of a stiff material, the ribs being fastened along their length to the second surface of the panel.

In a subsidiary aspect the invention comprises a panel, wherein the sheet material is reinforced with strengthening ribs made of pressed steel, the ribs being In a related aspect the invention comprises a panel, wherein the strengthening ribs are fastened to the second surface of the panel along a first axis, and a second series of extended deformations applied to the surface of the sheet are made along a second axis in a perpendicular direction.

In a second broad aspect the invention comprises a panel, wherein the panel is affixed to a concealed support by means of one or more fasteners passing through the panel and one or more strengthening ribs included in the panel. In a third broad aspect the invention comprises a panel, wherein the increased thickness is formed from the bulk of the sheet material by a pressing or rolling action capable of modifying the thickness of the sheet material prior to or coincident with a pressing action capable of creating each extended fold or curve adjacent to at least one load-bearing portion of the panel.

In a related aspect the invention comprises a panel, wherein a method for making a panel as described above, comprising the steps of (a) selecting a ductile material, (b) rolling the panel between rollers so that the panel becomes thinner in parts, and (c) further rolling or pressing the panel so that the less thin parts receive a pattern of folds or curves having their summits towards a first surface.

In a fourth broad aspect the invention comprises a panel, wherein the increased thickness is formed from the bulk of the sheet material by a pressing or rolling action capable of folding the sheet so that a plurality of layers of the sheet material lie beneath each extended fold or curve adjacent to at least one load-bearing portion of the panel.

In a related aspect the invention comprises a panel, wherein the additional member or members are in the shape of struts, or bands.

In a further broad aspect the invention comprises a panel for covering a portion of a building or the like, wherein the materials comprising the panel are optimised in position and strength so that the panel, even though relatively light, can support a greater weight of a person or of solid precipitation (snow, hail, or volcanic ash)than can an unmodified panel of similar bulk.

Preferably, anti-corrosion coatings are applied.

Preferably the appearance of each panel may simulate a matrix of tiles.

In a further broad aspect the invention comprises a panel, wherein the panel is made by deforming sheet material; the roof tile incorporating one or more additional members made of a stiff material joined to the roof tile adjacent to at least one load-bearing portion of the tile, the tile so modified being provided with increased stiffness and capability to withstand a load from above (when in place) in at least those portions of the tile.

Preferably the stiff material is compatible with the roofing tile in relation to corrosion.

Preferably the stiff material is compatible with the roofing tile in relation to manufacturing procedures; particularly in joining operations.

Optionally the roofing tile and the stiff material may be made of different materials. - -

Preferably a metal roofing tile made of a pressed steel sheet is reinforced with strengthening ribs made of pressed steel; galvanised or otherwise corrosion protected in the same manner as is the original steel sheet.

Alternatively a roofing tile may be strengthened by provision of a additional member or members adherent to a spacing "core" of relatively low strength or stiffness, which in turn is adherent to a portion of the roofing tile to be strengthened.

In yet another broad aspect the invention comprises a method for making a strengthened roofing tile by taking a roofing tile at a suitable point in its manufacturing process, and incoφorating one or more additional member or members of a stiff material at a position beneath or adjacent to a load-bearing portion of the tile.

DRAWINGS OF PREFERRED EMBODIMENT

One preferred form of the invention will now be described with reference to the accompanying drawings. It should be realised that this preferred embodiment is in no way limiting as to the scope and spirit of the invention.

Fig. 1 is a general view (taken from a photograph) according to one preferred panel of the invention 100, showing its upper surface 103 with ridges 104. The dimensions "A" (101) and "B" (102) can be varied to suit the particular application, but typical values for these dimensions would be 1350 mm and 400 mm respectively. The overall profile of the panel 100 can take a wide variety of forms.

Fig. 2 is an under-surface view of a panel 200 showing a typical disposition of the strengthening ribs 202 on the undersurface 201. This panel has the strengthening ribs attached, but it has not yet been moulded to have ridges. The number of strengthening ribs in the panel can vary (depending on the design of the simulated tile and the number of ridges in any one panel), and the width and thickness of each strengthening rib could vary at different points throughout the length of the rib. The ribs could be of a single material (e.g. metal or plastic) or could be of a composite material (e.g. resin impregnated paper).

Fig. 3 shows a diagrammatic section through a panel at the position of a strengthening rib. The adhesive 301 is shown, between the panel 201 and the strengthening rib, 202.

Fig 4 shows a diagrammatic section through a portion of a roof panel 401 according to another form of the invention, in which a material is rolled or otherwise deformed so that its thickness is increased beneath the raised points 104. Fig 5 shows a diagrammatic series of sections, showing one way to manufacture a roof panel according to another form of the invention, in which a sheet material is folded or pleated so that its thickness is increased beneath the raised points 104.

EXAMPLE OF PREFERRED EMBODIMENT

This example (see Figs 1-3) employs stiffening ribs of steel beneath the "high points". Please note that the dimensions given are for a prototype intended for tests of the manufacturing methods, and it may be convenient to extend the width and height of the panel beyond the dimensions given, or to adopt an industry standard dimension for a multiple of tiles so that this type of panel can replace some or all of an existing roof.

Material: 0.4 mm aluminium sheet. After deformation into a configuration resembling 3 (wide) x 1 tile, the dimensions are 480 mm wide, 420 mm high. From lower edge to upper edge, the top surface exhibits (1) a rising ledge 105 of 20-28 mm height (depending on deformation of the surface) leading onto a "tile" surface (B; 102) 380 mm long, then another rising ledge of about 30-35 mm height ( again depending on deformation of the surface) and then a horizontal surface 106 (again configured to resemble a tile) of about 27-35 mm. The rising ledges have a scalloped appearance, as seen from above, presumably as a consequence of a minimum-stress bending operation. The most "upward" portions of the scallops are at each high point 104 of the "unit ridges". While the example shows a double ridge, other numbers of ridges are possible. Moving across the tile surface from left to right, there is a partial tile, wherein each "unit tile" is a sweeping depression leading up to a pair of ridges, then another "unit tile" surface commences; this is repeated, and finally a partial "unit tile" of 42 mm width - to be inserted underneath an adjoining panel is provided. Underneath each pair of ridges of a "unit tile" there is symmetrically placed a strip of steel, known to the inventor as a "rib", aligned parallel to the ridges. This steel strip 202 in the example is 65 mm wide, 0.4 mm thick, and is bonded to the aluminium with a NF 2000 (3M Corp) adhesive (as at 301) intended for metal-to-metal bonds in aircraft construction. Bonding is carried out by an application of heat prior to deformation of the flat assembly into the configuration resembling a tiled surface, so minimising assembly problems. Of course other fastening techniques may be used. After the reinforcing rib has been configured it will have increased stiffness.

The panel is preferably attached to a roof by nails; more preferably by screws, or by other suitable fasteners applied through the second rising ledge, in a direction generally parallel to the roof surface and into the surfaces of battens running along the roof. This fastening method has the advantages that the fasteners, if used adjacent to the ridge lines of the "unit tiles", also penetrate the reinforced ribs, so that fastening does not rely on the relatively weak aluminium sheet, and that if forces such as extreme wind pressure tend to pull the roof panels up and off then the forces tend to shear the fasteners which takes more force than to than pull them straight out. Furthermore it may be possible to economise on battens if two-tile-high or more panels are used. In some countries, wood even of a quality suitable for battens is quite expensive.

The overall objective is to produce a roof tile panel that complies with a specified strength requirement whilst incoφorating a minimum amount of material and thereby satisfies the objective of minimal material cost. A New Zealand building standard requires a roof tile to be able to hold a 100 Kg mass, distributed over a 100 mm x 100 mm square, on any part without structural failure. Providing the same strength with a tile of uniform thickness results in excess material on the less stressed portions.

Reasons to minimise the use of material include (a) reduced total roof weight, useful in construction and in withstanding stresses due to earthquakes, etc, (b) reduced cost of materials, so that the tiles may be cheaper than tiles of the same material not having the strengthening ribs, or so that more expensive roofing materials that are otherwise too expensive may be used. Examples of more expensive materials that become feasible for general use with the invention include copper (or alloys including copper), or a stainless steel/plain steel laminated construction, and perhaps even a stainless steel. Other cuπently available materials to be considered here are "Zincalume" (TM) which is zinc-coated aluminium, or "Galvan" (TM) which is an equivalent. Plastics may be used for the panel, again reinforced by steel strips or the like. Nowadays plastics are satisfactory for roofing applications without significant degradation - eg "Novaroof ' or polycarbonate corrugated skylights, or plastic spouting. Polyvinyl chloride (PVC) is widely used for spouting and for weatherboards. Plastic roofing tiles have hitherto been impractical because of their relatively excessive flexibility in affordably thin sheets. With reference to the drawings, plastic could be substituted for the body of the panel 201, or could be used with a manufacturing method that varies the panel thickness, resulting in an appearance such as at 401 in Fig 4. PVC panels would generally be blow-moulded but other plastics could be cast. Deformation of thermoplastics may result in intolerable stresses which result in early failure under environmental exposure.

Suφrisingly, the extra steps involved in manufacturing these composite roofing panels have been estimated to cost less than the extra cost of material required to meet strength standards without using the principles of the invention: varying the thickness of construction. Different materials can be used for the ribs and tile panel, thereby allowing an expensive lightweight material such as (but not limited to) aluminium (in a thin gauge) to be used for the tile panel, and a lower cost material such as (but not limited to) steel, to be used for the strengthening ribs, without incurring an overall material cost penalty for the marketed product. Corrosion of the steel is unlikely to be a problem because it is generally used on the protected surface of the panel; a coat of paint should suffice.

Various methods of manufacture could be adopted rather than that described for the prototype. For instance, the individual components could be preformed at different locations and brought together in a separate operation (or operations). For affixing puφoses, the use of an adhesive as described above, fasteners, "spot" welding or mechanical interference may be used in various forms, either singly or in combination to bind the components together. Alternatively, the components may be formed and bound together in a single operation. Alternatively, rolling could be used to create thick and thin zones ( see Fig 4) prior to sheet configuration to resemble an array of tiles. Alternatively, a combination of these methods may be used.

An existing forming operation may be modified so that (for example) an existing, or an added ridge is made wider in the centre of the tile than at the edges, or other sculpting, such as wrinkles aligned substantially peφendicular to the line of the ridge are included. The machinery and operator skills required to perform the foregoing manufacture operations are readily available in the public domain and it is not a part or puφose of this patent to associate any particular manufacturing process or procedure as an inherent requirement for the manufacture of the strengthened roof tile of the type described in this patent application.

VARIATIONS

The diagrammatic series of sections shown in Fig 5 illustrates one way to manufacture a roof panel according to another form of the invention, in which a sheet material such as steel or aluminium is folded or pleated so that its thickness is increased beneath the raised points 104. (Radii of folds are exaggerated). While several individual steps are shown here, this procedure lends itself to continuous forming operations. 501 illustrates a section through a first stage, where a raised fold has been created.

It has been flattened in 502, and the form 503 shows an overall outwards curve, so forming a high point 104 which has increased capability for bearing weight as a result of (a) the curve, and (b) the three layers of material incoφorated beneath the high point. In the case of those coatings likely to become detached during or after the folding action, we prefer to apply a protective coating after the folding action, and the coating should preferably prevent the ingress of water or the like into the folded structure, so reducing the risk of corrosion. Clearly this method of making a strengthened strip may be varied, even by incoφorating further materials within the folding operations. Indeed, solar heated water might be made by forming or incoφorating conduits 504 within the folds.

While a roof tile pressed from steel was considered during the preparation of the preferred embodiment, the same principles may be applied to tiles made of other materials, such as roof tiles pressed from other metals or pressed (perhaps with the aid of heat) from thermoplastic plastics materials, or even classical ceramic tiles (fired clay, whether glazed or not - in which case strengthening may comprise thicker material along ridges), tiles made by compressing a cement slurry, or tiles made from other materials using other forming processes.

Furthermore, reinforcement according to the invention may be applied to panels in which the extended deformations comprise, not ridges as seen from the surface exposed to the weather (the "first" surface in the claims) but valleys. This type of construction is seen in plastic weatherboard panels and a similar arrangement could be used on roofs. The invention may be applied to panels according to the format of long-run roofing sheets as well.

ADVANTAGES

The invention allows roof panels to be made that meet load-bearing strength requirements yet include less overall material than prior-art roof coverings, thus are cheaper and lighter - or may allow the use of thin layers of more expensive materials.

It follows that the production of a panel to be produced with this patent application will allow the profile of the panel to be produced with considerably less force or pressure than would otherwise be required if a panel of uniform thickness (to give the required strength) were used. This could result in a reduced capital investment in machinery and/or higher productivity. The resulting panel would be significantly lighter than a similar one of the same strength made from a single panel of uniform thickness. This would make the panel which incoφorates the proposed strengthening ribs, easier to handle and less expensive to transport. The strength of the supporting construction to hold the roof in place may be reduced, for other roof construction methods (such as concrete tiles) result in a ten times increase in roof weight. Less building materials are required to support a lighter roof. Lighter roofs are an advantage in case of earthquakes or other disasters when falling material may harm people.

Means for fixing these panels to a support structure are effective, because the screws or nails used (screws are preferred) can be arranged to penetrate the strengthened portions of the panels. They hold better during adverse weather, because the fasteners are exposed to shear forces rather than lengthwise extraction forces. During attachment, the position of strengthening strips beneath the outer surface of the panel is obvious from the outer side of the roof. They are under the ridges.

In summary, this invention comprises an optimised panel in which the structural material is concentrated at positions likely to be required to bear imposed loads. Material savings, cost savings, and weight savings result from this improvement.

Finally, it will be appreciated that various alterations and modifications may be made to the foregoing without departing from the scope or spirit of this invention as set forth in the following claims.

Claims

CLAIMS:

1. A panel for covering or weatheφroofing puφoses comprised of a sheet material, the panel having a first surface which may be exposed to the weather when in use, and having a second surface, and having one or more deformations n the form of folds or ridges generally protruding from the first surface, characterised in that the panel is provided with additional material along at least a part of the length of at least some deformations, so that the panel remains relatively light in weight yet is provided with increased stiffness and increased capability to withstand a load.

2. A panel for covering or weatheφroofing puφoses comprised of a sheet material, the panel having a first surface which may be exposed to the weather when in use, and having a second surface, and having one or more deformations n the form of folds or ridges generally protruding from the first surface, characterised in that the panel is provided with additional material along the length of at least some deformations, so that the panel remains relatively light in weight yet is provided with increased stiffness and increased capability to withstand a load.

3. A panel for covering or weatheφroofing puφoses comprised of a sheet material, the panel having a first surface which may be exposed to the weather when in use, and having a second surface, and having one or more deformations n the form of folds or ridges generally protruding from the first surface, characterised in that the panel is provided with additional material along the length of all deformations, so that the panel remains relatively light in weight yet is provided with increased stiffness and increased capability to withstand a load.

4. A panel as claimed in claim 1, characterised in that the additional material at the position of each extended deformation is comprised of one or more additional members attached to the second surface of the panel, the tile so modified being provided with increased stiffness and increased capability to withstand a load.

5. A panel as claimed in claim 4, characterised in that the additional member or members are laid down in a pattern of ribs; each rib being applied to an extended deformation.

6. A panel as claimed in claim 5, characterised in that the sheet material is a metal panel, reinforced with strengthening ribs made of a stiff material.

7. A panel as claimed in claim 6, characterised in that the sheet material is reinforced with strengthening ribs made of pressed steel, the ribs being fastened along their length to the panel.

8. A panel as claimed in claim 7, characterised in that the strengthening ribs are fastened to the panel along a first axis, and a second series of extended deformations applied to the surface of the sheet are made along a second axis in a peφendicular direction.

9. A method for affixing a panel as claimed in claim 8, characterised in that the panel is affixed to a concealed support by means of one or more fasteners passing through the panel and passing through one or more strengthening ribs included in the panel.

10. A panel as claimed in claim 4, characterised in that the sheet material is a panel made of a plastics material, reinforced with strengthening ribs made of a stiff material, the ribs being fastened along their length to the panel.

1 1. A panel as claimed in claim 1, characterised in that the increased thickness is formed from the bulk of the sheet material by a pressing or rolling action capable of modifying the thickness of the sheet material prior to or coincident with a pressing action capable of creating each extended fold or curve adjacent to at least one load-bearing portion of the panel.

12. A panel as claimed in claim 1, characterised in that the increased thickness is formed from the bulk of the sheet material by a pressing or rolling action capable of folding the sheet so that a plurality of layers of the sheet material lie on the second surface of the panel, beneath each extended fold or curve adjacent to at least one load-bearing portion of the panel.

13. A method for making a panel as claimed in claim 11, comprising the steps of (a) selecting a ductile material, (b) rolling the panel between rollers so that the panel becomes thinner in parts, and (c) further rolling or pressing the panel so that the less thin parts receive a pattern of folds or curves having their summits towards a first surface.