AU2012268792B2

AU2012268792B2 - Roofing or cladding sheet and method of forming

Info

Publication number: AU2012268792B2
Application number: AU2012268792A
Authority: AU
Inventors: Rodney Donald Newbold; Anthony George Rallis
Original assignee: Steel & Tube Holdings Ltd
Current assignee: Steel & Tube Holdings Ltd
Priority date: 2011-12-22
Filing date: 2012-12-20
Publication date: 2017-04-27
Anticipated expiration: 2032-12-20
Also published as: AU2012268792A1

Abstract

Abstract An improved ribbed roofing or cladding sheet and a method of forming said sheet ,wherein the ribbed roofing or cladding sheet includes a plurality of ribs extending along the roofing or cladding sheet; one or more pans between the ribs; in cross-section, each rib includes a web having a first inclined section that extends upwards from a pan on an angle towards a mid-point of the rib and a second inclined section that extends upwards from the top of the first inclined section on an angle towards the mid-point of the rib; and wherein the first and second inclined sections together forming a generally concave web surface with a bend between the first and second inclined sections extending along the length of the generally concave web surface. U-

Description

1

ROOFING OR CLADDING SHEET AND METHOD OF FORMING FIELD OF THE INVENTION

The invention relates to roofing or cladding materials, in particular to ribbed roofing or cladding materials.

BACKGROUND TO THE INVENTION

Metal roofing materials such as steel, copper and the like are widely used. Steel roofing is often coated, e.g. by galvanising or with a zinc-aluminium alloy.

Various profiles are used for different applications. These profiles include simple corrugated profiles and ribbed profiles, and are usually roll-formed. Figure 1 shows an existing ribbed profile. This profile consists of trapezoidal ribs 1 separated by so-called “pans” 2. The pans 2 generally define a plane and the ribs 1 extend from that plane. The roofing material is attached to supporting purlins by driving roofing screws through the top of the ribs. The screws extend into the purlins that lie beneath the plane defined by the pans.

Each rib includes two side portions, known as “webs” 3, and a top portion, known as a “crest” 4. The profile has a “pitch” defined as the distance 6 between the same point on adjacent ribs and a depth that is the distance from the highest point to the plane of the pans.

Roofing sheets are generally installed side by side, with the partial side ribs 8 of adjacent sheets overlapping.

Ribbed roofing sheets include standard or low rib sheets, and high rib sheets. High rib sheets are used, usually in industrial buildings, where the span between supporting purlins is large. The higher rib shape provides greater strength and 2 rigidity, allowing these longer spans to be covered. High rib roofing sheets have a depth greater than 35mm.

Ribbed sheets can be contrasted with standing seam roofing material, in which vertical elements at the sides of adjoining panels are joined by a physical rolling or seaming process after the material is positioned on the roof. Standing seam material is usually attached by non-penetrating clips and does not provide structure over long spans. In fact standing seam roofing is usually supported by plywood or similar material over its entire coverage area.

Ribbed materials may also be used in cladding the walls of buildings. In this specification the term “cladding” means wall cladding, not roof cladding. Roof cladding is included in the term “roofing”.

Reference to any prior art in this specification does not constitute an admission that such prior art forms part of the common general knowledge.

It is an object of the invention to provide an improved ribbed roofing or cladding material, or at least to provide the public with a useful choice.

SUMMARY OF THE INVENTION

In a first aspect the invention provides a ribbed roofing or cladding sheet including: a plurality of ribs extending along the roofing or cladding sheet; one or more pans between the ribs; wherein: in cross-section, each rib includes two opposing webs, each web having a first inclined section that extends upwards from a pan on an angle towards a mid-point of the rib and a second inclined section that extends upwards from the top of the first inclined section on an angle towards the mid-point of the rib, the first and second inclined sections together forming a generally concave web surface with a bend between the first and second inclined sections extending along the length of the generally concave web surface; and each rib further includes 3 a crest extending between the tops of the two opposing webs, wherein the crest, in cross section, includes: two opposing outer sections, each outer section extending inwards towards the mid-point of the rib from the top of one of the opposing webs and then upwards; and an inner cap that extends between the two outer sections.

Preferably the first inclined section extends at an obtuse angle to the pan from which it extends. Preferably the first inclined section extends at an obtuse angle of between 120 and 135 degrees to the pan from which it extends. Preferably the first inclined section extends at an obtuse angle of between 120 and 132 degrees to the pan from which it extends. Preferably the first inclined section extends at an obtuse angle of around 127 degrees to the pan from which it extends.

Preferably the second inclined section extends at an obtuse angle to the first inclined section. Preferably the second inclined section extends at an obtuse angle of between 160 to 175 degrees to the first inclined section. Preferably the second inclined section extends at an obtuse angle of between 162 to 174 degrees to the first inclined section. Preferably the second inclined section extends at an obtuse angle of around 168 degrees to the first inclined section.

Preferably each rib further includes a crest extending between the tops of two opposing webs, and wherein the crest, in cross section, includes: outer sections that extend inwards from the tops of the opposing webs and then upwards; and an inner cap that extends between the two outer sections.

Preferably the inner cap is convex. Preferably the inner cap has a radius of curvature between 50 and 150 millimetres. Preferably the inner cap has a radius of curvature between 50 and 100 millimetres. Preferably the inner cap has a radius of curvature of around 75 millimetres. 4

Preferably the ribs include: a partial rib at each side of the roofing sheet configured, when installed, to overlap with a partial rib of an adjacent roofing or cladding sheet; and one or more full ribs between the partial ribs.

Preferably the full ribs are symmetric.

Preferably the sheet is a high rib sheet wherein the ribs are high ribs.

Preferably the sheet is a roofing sheet.

In a second aspect the invention provides a method of forming a ribbed roofing or cladding sheet, including: providing a sheet material, and roll-forming the sheet material to form: a plurality of ribs extending along the roofing or cladding sheet; and one or more pans between the ribs; wherein in cross-section, each rib includes two opposing webs, each web having a first inclined section that extends upwards from a pan on an angle towards a mid-point of the rib and a second inclined section that extends upwards from the top of the first inclined section on an angle towards the mid-point of the rib, the first and second inclined sections together forming a generally concave web surface with a bend between the first and second inclined sections extending along the length of the generally concave web surface; and each rib further includes a crest extending between the tops of the two opposing webs, wherein the crest, in cross section, includes: two opposing outer sections, each outer section extending inwards towards the mid-point of the rib from the top of one of the opposing webs and then upwards; and an inner cap that extends between the two outer sections.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example only, with reference to the accompanying drawings, in which: 5

Figure 1 Figure 2 Figure 2A Figure 3 Figure 3A Figure 3B Figure 4 Figure 5 is a cross-section through a prior art roofing sheet; is a perspective view of a roofing sheet according to one embodiment; is an expanded view of part of the roofing sheet of Figure 2; is a cross-section through the roofing sheet of Figure 2; is an expanded view of part of the roofing sheet of Figure 4; is a similar view to Figure 3A illustrating certain dimensions of one embodiment of roofing sheet; shows how two adjacent roofing sheets overlap; and shows a number of roofing sheets fixed to a supporting structure.

DETAILED DESCRIPTION

Figure 2 is a perspective view of a high rib roofing sheet 10 according to one embodiment. Figure 2A is an expanded view showing the high rib profile of Figure 2. The roofing sheet has a generally trapezoidal high rib profile. However, as discussed below the rib profile is more complex and stronger than in prior high rib roofing.

The roofing sheet 10 may be roll-formed from any suitable material, including steel with any suitable coating, such as galvanised steel or zinc-aluminium alloy coated steel. The sheet may also have an organic coating, such as an organic paint coating and/or may be coloured by any suitable process.

The high rib roofing sheet 10 is shown in cross-section in Figure 3. The roofing sheet 10 includes a number of high ribs 11 separated by pans 12.

The pans may include low ridges or swages 13, but these form no part of the invention. 6

The shape of the high ribs 11 is shown in detail in Figure 3A. Each side or web 15 of the rib 11 is formed in two sections. A lower inclined section 16 extends upwards from the pan 12 at an obtuse angle Θ. The lower inclined section 16 is angled in towards a mid-point of the high rib, indicated by the dashed line in Figure 3A. An upper inclined section 17 extends upwards from the top of the lower inclined section 16 at an obtuse angle 0. The upper inclined section 17 is also angled towards a mid-point of the high rib, indicated by the dashed line in Figure 3A.

The lower and upper inclined sections 16, 17, together define a generally concave web due to the angle 0 between them. The bend 18 between these two sections extends along the length of the rib, as can be seen in Figure 2. A crest 19 extends between the upper points of the two opposing webs 15. The crest 19 includes outer sections 20 that are each formed in two parts. These outer sections include a first portion 21 extending inwards from the top of the web 15 and a second portion 22 extending upwards from the first portion 21. A cap 24 extends between the two second portions 22.

The cap 24 is preferably slightly convex. The cap may have a radius of curvature between 50 and 150 mm preferably between radius of curvature between 50 and 150 mm, ideally around 75 mm.

In some embodiments the second portions 22 and cap 24 may be formed in a single continuous curve.

The angle Θ may be between 120 and 135 degrees, preferably between 120 and 132 degrees, ideally around 127 degrees.

The angle 0 may be between 160 to 175 degrees, preferably between 162 to 174 degrees, ideally around 168 degrees. 7

The high rib may have an overall height H (Figure 3B) of between 35 and 55 mm, preferably between 41 and 51 mm, ideally around 46mm. The bend 18 may be positioned above the pan by a distance Hi that is between 16 and 27 mm, ideally around 22 mm.

The height H2 of the outer crest section 20 may be around 2mm to 10mm, ideally around 5 to 6 mm. The three bends 20a, 20b, 20c (Figure 3a) in the outer crest section 20, as well as the bend 12a where the high rib meets the pan, may have bend radii between 1 and 5 mm, preferably around 2-3mm.

The overall width W of the high rib may be between 80 and 100mm, preferably between 85 and 96 mm, ideally around 91mm.

The width W1 of the crest’s inner cap 24 may be between 15 and 35 mm, preferably between 20 and 30mm, ideally around 25mm.

The width W2 of the outer crest section, measured perpendicular to the upper inclined section 17, may be around 2 to 10mm, ideally around 4mm.

The pitch of the roofing profile is not critical, but may be around 320mm in some embodiments.

Figure 4 shows how the sides of two adjacent roofing sheets 10 overlap. As shown in Figure 3 a partial high rib is formed at each side of the roofing sheet 10. The partial high rib 30 includes an outer element 31 that is formed at an angle to fit inside the opposite partial high rib 32 of an adjacent sheet. A roofing screw can be driven through both partial high ribs 30, 32 thereby fixing the two roofing sheets 10 together.

Figure 5 shows a number of roofing sheets 10 fixed to an underlying structure. The roofing sheets 10 are laid over a number of purlins 35, with the high ribs running 8 transverse to the lengths of the purlins 35. A roof underlay and/or support netting and/or safety mesh may be laid between the roofing sheets and the purlins, as required for the application or building code. Roofing fasteners 36 (usually screws, although other methods of fixing may be used) are installed through the tops of the high ribs and into the purlins 35. Washers 37 are positioned between the heads of the fasteners and the roofing sheet to limit ingress of water.

The Applicant’s profile provides improved strength over traditional high rib profiles. The shape of the concave web 15 contributes to this increased strength. The effective length of the web is decreased by dividing it in two. Buckling resistance decreases in a manner proportional to the square of increasing web length. The bend 18, which extends along the length of the concave web 15, provides increased buckling resistance over a straight web, by effectively dividing the web in two. This significantly raises the critical buckling load of the panel, helping to prevent local panel buckling, which is often the onset of instability and ultimate collapse of a roofing section.

The outer sections 20 of the crest connect to the steeper upper inclined section 17 of the web 15. The bend 20a is more acute that would be the case if the web 15 were simply a flat panel with the same average angle as the two inclined sections 16, 17. This contributes to increased bending stiffness in this region. The series of bends 20a, 20b, 20c at this junction also contributes to increased bending stiffness.

The neutral axis of the rib is relatively close to the plane in which the pans lie. This means that the peak stresses will be towards the top of the profile. The profile shape helps to resist these stresses in the upper regions of the profile.

On the other hand the lower sections of the rib profile are well supported by the purlins and close to the neutral axis of the rib. The stresses on these regions are therefore lower and there is not the same need for local stiffness. 2012268792 25 May 2016 9

These improvements provide a stronger panel than in conventional high rib roofing. The Applicant’s roofing sheet is capable of spanning large distances between purlins, up to around 4000 mm. Furthermore, the increased strength makes the profile less sensitive to local imperfections in the material or introduced in 5 manufacturing.

The roofing sheet may be manufactured in any desired length or cover width.

While described mainly in the context of a high rib material, the Applicant’s profile 10 may also be applied in other ribbed material, including standard or low rib roofing materials. Furthermore, in some applications the Applicant’s material may be used as a cladding rather than a roofing material.

While the present invention has been illustrated by the description of the 15 embodiments thereof, and while the embodiments have been described in detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and methods, and 20 illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of the Applicant’s general inventive concept.

Claims

CLAIMS:

1. A ribbed roofing or cladding sheet including: a plurality of ribs extending along the roofing or cladding sheet; one or more pans between the ribs; wherein: in cross-section, each rib includes two opposing webs, each web having a first inclined section that extends upwards from a pan on an angle towards a midpoint of the rib and a second inclined section that extends upwards from the top of the first inclined section on an angle towards the mid-point of the rib, the first and second inclined sections together forming a generally concave web surface with a bend between the first and second inclined sections extending along the length of the generally concave web surface; and each rib further includes a crest extending between the tops of the two opposing webs, wherein the crest, in cross section, includes: two opposing outer sections, each outer section extending inwards towards the mid-point of the rib from the top of one of the opposing webs and then upwards; and an inner cap that extends between the two outer sections.
2. A roofing or cladding sheet as claimed in claim 1 wherein the first inclined section extends at an obtuse angle to the pan from which it extends.
3. A roofing or cladding sheet as claimed in claim 2 wherein the first inclined section extends at an obtuse angle of between 120 and 135 degrees to the pan from which it extends.
4. A roofing or cladding sheet as claimed in claim 2 wherein the first inclined section extends at an obtuse angle of between 120 and 132 degrees to the pan from which it extends.
5. A roofing or cladding sheet as claimed in claim 2 wherein the first inclined section extends at an obtuse angle of around 127 degrees to the pan from which it extends.
6. A roofing or cladding sheet as claimed in claim 1 or 2 wherein the second inclined section extends at an obtuse angle to the first inclined section.
7. A roofing or cladding sheet as claimed in claim 6 wherein the second inclined section extends at an obtuse angle of between 160 to 175 degrees to the first inclined section.
8. A roofing or cladding sheet as claimed in claim 6 wherein the second inclined section extends at an obtuse angle of between 162 to 174 degrees to the first inclined section.
9. A roofing or cladding sheet as claimed in claim 6 wherein the second inclined section extends at an obtuse angle of around 168 degrees to the first inclined section.
10. A roofing or cladding sheet as claimed in claim 1 wherein the inner cap is convex.
11. A roofing or cladding sheet as claimed in claim 10 wherein the inner cap has a radius of curvature between 50 and 150 millimetres.
12. A roofing or cladding sheet as claimed in claim 10 wherein the inner cap has a radius of curvature between 50 and 100 millimetres.
13. A roofing or cladding sheet as claimed in claim 10 wherein the inner cap has a radius of curvature of around 75 millimetres.
14. A roofing or cladding sheet as claimed in any preceding claim wherein the ribs include: a partial rib at each side of the roofing sheet configured, when installed, to overlap with a partial rib of an adjacent roofing or cladding sheet; and one or more full ribs between the partial ribs.
15. A roofing or cladding sheet as claimed in claim 14 wherein the full ribs are symmetric.
16. A roofing or cladding sheet as claimed in any preceding claim, being a high rib sheet wherein the ribs are high ribs.
17. A roofing or cladding sheet as claimed in any preceding claim, being a roofing sheet.
18. A method of forming a ribbed roofing or cladding sheet, including: a. providing a sheet material b. roll-forming the sheet material to form: a plurality of ribs extending along the roofing or cladding sheet; and one or more pans between the ribs; wherein in cross-section, each rib includes two opposing webs, each web having a first inclined section that extends upwards from a pan on an angle towards a mid-point of the rib and a second inclined section that extends upwards from the top of the first inclined section on an angle towards the mid-point of the rib, the first and second inclined sections together forming a generally concave web surface with a bend between the first and second inclined sections extending along the length of the generally concave web surface; and each rib further includes a crest extending between the tops of the two opposing webs, wherein the crest, in cross section, includes: two opposing outer sections, each outer section extending inwards towards the mid-point of the rib from the top of one of the opposing webs and then upwards; and an inner cap that extends between the two outer sections.