WO2003022578A1

WO2003022578A1 - Solar energy concentrating assembly and sub-components thereof

Info

Publication number: WO2003022578A1
Application number: PCT/AU2002/001243
Authority: WO
Inventors: Glen Harvey George Johnston; Keith Malcolm Lovegrove; Gregory John Burgess
Original assignee: The Australian National University
Priority date: 2001-09-11
Filing date: 2002-09-11
Publication date: 2003-03-20

Abstract

The present invention relates to a method for manufacturing a laminate by placing sheet material of each laminate component in a curved mould, applying pressure to form curved laminate and bonding components together while maintaining pressure. In particular the invention relates to curved glass-on-metal laminates for a solar energy reflective element. The invention also relates to other sub-components of a solar energy concentrating assembly including an edge moment support member or ribs for the ends of the reflective element and supports for the sides of the reflective element. The invention also relates to methods of fabricating the sub-components and the solar energy concentrating assembly as a whole.

Description

SOLAR ENERGY CONCENTRATING ASSEMBLY AND SUB-COMPONENTS

THEREOF

The present invention relates to a solar energy concentrating assembly and sub- components thereof. In particular the invention relates to solar energy concentrating assemblies including a large area reflective element, such as a mirror, and sub-components including laminates, such as glass-on-metal laminates (GOML), forming the reflective element, edge (or side) moment support members or "ribs" which support the ends of the reflective element and other support members or ribs which support the sides of the reflective element. The invention also relates to methods for the fabrication of the subcomponents and the solar energy concentrating assembly as a whole.

Many types of solar collectors and concentrators require curved reflective elements. These are required to both collect and concentrate solar radiation for use with an absorbing or energy converting element. As such, methods are required for the fabrication of sometimes large surface area curved reflective elements which are generally formed from a GOML. Systems are also required for the support of such reflective elements. Each of these requirements individually and collectively form the basis of various aspects of the present invention.

The present invention is primarily concerned with a solar energy concentrating assembly formed from a number of sub-components. Each of those sub-components will be described hereafter and is considered to individually form the basis of a particular aspect of the present invention, generally for use in the primary context of solar energy concentrating assemblies, and particularly for use in the assembly of the invention.

Generally, in a first aspect the invention provides a method for the manufacture of a laminated product including applying a pre-curvature to laminate components of the laminated product, and bonding the laminate components together. Such a laminate will generally form the basis of the laminate, particularly a GOML laminate, sub-component foraiing the reflective element here before described. More particularly, according to the first aspect of the invention there is provided a method for the manufacture of a laminated product including a plurality of laminate components, the method including: (i) placing sheet material of each laminate component in a curved mould;

(ii) applying pressure to or causing pressure to applied to the laminate components such that the laminate components conform to the shape of the mould; and (iii) bonding the laminate components together while the pressure is still being applied or caused to be applied.

The invention also provides laminated products manufactured by a method according to the immediately preceding paragraph. The invention further provides solar energy concentrating assemblies which incorporate a laminated product manufactured by the method.

Laminated products are of course known, the use of laminates being widespread in a number of different and widely varying fields. One such field is that of solar energy concentrating assemblies or collectors which can incorporate a laminate of glass and metal. In that regard, any reference to a "solar collector" herein should be taken as reference to a solar energy concentrating assembly.

As an example, reference is made to GB 2,042,761 which discloses optical reflectors including a glass layer which may be silvered. In particular the document discloses the bonding of glass to a metal substrate such as steel using a hot melt adhesive. Particular hot melt adhesives described include those which incorporate one or more elastomers or thermoplastics selected from butyl rubber and ethylene/vinyl acetate copolymers (EN A).

US 4,422,893 describes the bonding of a mirror element to a unitary support which may be formed from concrete, metal, plastics material or vitreous material. The bonding may once again be effected using a hot-melt adhesive. Generally, however, on the forming of the laminated products of the prior art, particularly laminated products of components of different materials, problems may be encountered in that the laminate may develop significant convex curvatures if curved into a shape for use in fields such as the optical concentration of solar radiation. Such curvatures are particularly evident at the sides of the laminated units and may be detrimental to the performance of the product. This is particularly evident if two components, such as those having significantly different temperature coefficients of expansion, for example glass-iron or glass-aluminium, are bonded together to form a laminated product. This is, as described above, generally the case in the art of solar collectors.

The first aspect of the invention advantageously provides an alternate means for preparing a laminated product, such as a solar collector, whereby problems associated with curvature defects are advantageously minimized.

According to the first step of the method of the first aspect of the invention, sheet material of each of the laminate components of the laminated product are placed in a curved mould. The mould may be formed from any suitable material, provided that this can support the laminate components and is not deformed on subsequent vacuuming operations. Further, the mould is formed with a predetermined pre-curvature as will be dealt with hereafter with reference to the accompanying drawings. However, the radii of curvature, the placement and extent of the curved sections of the mould are specific to each application desired for the finished laminated product. It has been found that up to three, or possibly more different regions and radii of curvature per half of the mould can be effective in providing desirable shape conformance. The determination of the radii of curvature, their placement and extents is most directly undertaken using finite element analysis (FEA) modelling.

The laminate components of the laminated product will depend on the intended use of the product. Discussion herein will primarily be directed to a preferred area of use of the laminated product, solar collectors, but it should be understood that the present invention is considered to have a much broader application than this particular field.

In one particular embodiment, the laminate components include a metal component and a glass component. That is, the laminate is a Glass-On-Metal-Laminate, or GOML. These are the primary components used in the manufacture of such solar collectors. It will be understood that such components can have significantly different temperature coefficients of expansion which may result in undesirable deformations, such as convex curvatures described herebefore. The first aspect of the invention advantageously alleviates problems associated with the differences in temperature coefficients of expansion of the laminate components of the laminated product.

In a particular embodiment, a first laminate component includes a metal sheet. This may be a coated or uncoated iron or aluminium metal sheet, and preferably has a thickness of from about 0.4 - 1 mm. In a particularly preferred embodiment, the thickness of the metal substrate is about 0.8 mm.

A second laminate component preferably includes a glass sheet, for example a mirror- backed glass sheet. Preferably, the glass sheet has a thickness ranging from about 0.6 - 1.0 mm.

The metal substrate thickness is preferably chosen such that the neutral axis of the laminate composite is placed some distance into the metal layer, making allowances for the imperfect transferral of stresses by an adhesive layer between the metal and the glass layers.

In the preferred embodiment, the glass and metal laminate components are placed in the mould in sheet form. Preferably, a fusable film is placed between the glass and metal laminate components to facilitate bonding of the glass to the metal component to form a rigid structure. The preferred thickness of the films is about 100 micron, although it is envisaged that films from about 50 micron to 200 micron may be useful as the fusable film.

The bond line temperature of the fusable film is preferably between about 80°C - 180°C. The softening temperature of the film is preferably chosen such that it exceeds any expected temperatures the panel could experience in its designed exposure situations.

In an alternative embodiment, it is envisaged that the laminate components may mclude two glass components, such that glass sheets are bonded either side of the metal sheet. This embodiment produces a symmetric, and hence thermally stable laminate structure. Further laminate components may include polymeric substrates, such as acrylic sheet, polycarbonate compounds or fibreglass composites.

The next step in the method of the first aspect of the invention involves applying pressure to the laminate components. Preferably this includes sealing a vacuum bag over the laminate components, applying a vacuum to the vacuum bag such that pressure outside the bag causes the laminate components to conform to the shape of the mould, wherein the laminate components are bonded together while the vacuum is still being applied.

The vacuum bag is sealed along its edges so as to seal the laminate components under the vacuum bag. The vacuum bag, according to one embodiment, includes a 0.1 mm thick plastic film vacuum bag of nylon. However, it is envisaged that any suitable material may be used in the vacuum bag, provided that a suitable vacuum can be pulled to cause the laminate components to conform to the shape of the mould. In this regard, on applying the vacuum to the vacuum bag, preferably over a range from about -40 kPa to -100 kPa vacuum, the pressure outside the bag, for example atmospheric pressure, causes the bag to press down on the laminate components and conforms the laminate components to the shape of the mould. In an alternative embodiment, a vacuum bag is not placed over the laminate components. Rather, the laminate components are brought into conformity with the mould surface using a pressure bag which forces the components down into the mould during filling of the bag.

While the laminate components are in the compressed state, they are bonded together without releasing the vacuum or pressure bag. In this regard, bonding may be achieved in a preferred embodiment by melting a fusable film as described above between the laminate substrates so as to bond the substrates together forming a rigid structure.

Generally, in the prior art, problems occur as the bonded product is cooled down. In this regard, the fusable film generally solidifies at a temperature significantly higher than ambient, and on further cooling, in the case of a glass on metal laminate, the metal contracts at a greater rate than the glass and convex curvature is created where the metal at the bottom contracts to a larger extent than the glass on top. The inclusion of precurvature formed by compression onto the mould in the present invention advantageously corrects the convexity to result in a final product that conforms more easily to the final desired shape.

A more detailed description of one embodiment of the first aspect of the invention will be provided with reference to the accompanying drawings hereafter.

The second aspect of the present invention relates to edge (or side) moment support members or "ribs" which when used in the solar energy concentrating assembly of the invention support the ends of the reflective element of the assembly. For convenience the edge (or side) moment support member will be referred to as an "edge-moment rib".

The edge-moment rib according to the second aspect of the invention may advantageously be used to apply torque to a sheet of material. In particular, this aspect of the invention relates to an edge-moment rib for applying torque to a composite material, such as a glass- on-metal laminate, to bring the composite material to a desired degree of curvature. The fabrication of composite materials such as glass-on-metal-laminates (GOML) is known as discussed above. For example, GOML sheeting may be used as reflective elements in solar concentrator devices. Generally, such fabrication creates a structure with internal stresses which are mostly apparent around the perimeters of the composite material. These internal stresses may cause distortions, such as convex curvatures, at the edges of the GOML material, such distortions being counterproductive to the process of forming a GOML sheet material into a shape suitable for use in high accuracy solar concentrator devices.

It has been found that the distortions arising during GOML fabrication processes may be significantly corrected by the application of an edge-moment, or twisting force, at the peripheral edges of the GOML sheet. Such a force advantageously curves the edges of the GOML into the desired shape, be that parabolic, paraboloidal or spherical. The application of edge-moments to composite sheets to provide shape correction has also been described in the literature, such disclosures are limited and generally fail to realise the advantages of the present invention as described hereafter.

According to the second aspect of the invention there is provided an edge-moment rib for applying torque to a sheet of material including: a body portion; an outer lip portion extending from the body portion; and an inner lip portion disposed beneath the outer lip portion; wherein the inner lip portion and outer lip portion extend along the length of the edge- moment rib and in use engage an edge of the sheet material, the opposing faces of the inner lip portion and the outer lip portion converging on each other from each end of the edge- moment rib towards the centre of the edge-moment rib.

The invention further provides solar energy concentrating assemblies which incorporate an edge-moment rib as described in the immediately preceding paragraph. As stated above, the edge-moment rib includes a body portion, an outer lip portion and an inner lip portion. As defined, the inner and outer lip portions extend along the length of the edge moment rib and have opposing faces which converge. That is, the distance between the opposing faces of the inner and outer lip portions gradually decreases from each end of the edge-moment rib towards the centre thereof. It has been found in making this aspect of the invention, that the application of the necessary moments to the edge- moment rib usually occurs at the ends of the rib, which means that the moment must penetrate along the length of the rib to be applied to the complete length thereof, and consequently to the complete length of the edge of the composite sheet. Due to the physical properties of the sheet metal materials from which the edge-moment rib is made, torsional twisting along the length of the rib occurs such that the desired edge moment application to the edge of the composite sheet does not occur uniformly along the length of the edge. Rather, the moment is stronger at the ends of the edge-moment rib, near to the mounting points of the rib, and weaker in the central region of the rib.

In accordance with the second aspect of the invention the distance between the opposing faces of the inner and outer lips decreases towards the centre of the edge-moment rib to compensate for the non-uniform moment application caused by the material flexure of the edge-moment rib. Advantageously, this results in a moment which is applied to the whole rib mounted on the edge of the composite sheet resulting in a stronger moment to occur at the rib centre than at the rib ends, compensating for the natural flexure in the edge-moment rib.

The body portion, outer lip portion and inner lip portion may be provided by any suitable means. For example, the outer lip portion may be attached to or integral with the body portion. Furthermore, the outer lip portion may extend from one end of the body portion or may extend from any point along the body portion, provided that the inner lip portion is disposed beneath the outer lip portion. In a preferred embodiment, the outer lip portion is integral with the body portion and extends from an upper edge of the body portion. Similarly to the above, the inner lip portion may be integral with the body portion or may be provided by an attachment to the body portion. Thus, in one embodiment, the inner lip portion is provided by an attachment which is fastened to the body portion along the length of the body portion. In another embodiment, the inner lip portion forms part of the body portion in which case the outer lip portion may be bridged with the inner lip portion by a j oining portion of the rib.

A more detailed description of embodiments of the second aspect of the invention will be provided with reference to the accompanying drawings hereafter.

A third aspect of the invention relates to an improved method for holding a curved profile on a sheet of material, which can have many applications, but is again applied in the first instance to the process of reflecting solar radiation in solar energy concentrating assemblies.

Methods for maintaining a desired shape in a sheet of reflective material are known. These methods include various means for maintaining the desired shape ranging from curved ribs placed under the reflective sheet and using a range of methods of holding the sheet down onto the ribs to cutting curved slots into thick end-plate materials into which the reflective sheet is inserted to hold the desired profile at its edges. However, these methods generally suffer from high material costs, complex or slow production and manufacturing processes, high weight or a combination of these problems. They can also suffer from difficulty in changing the profile or shape rapidly, if required, particularly if they utilise some die or tooling components that may be difficult and costly to alter.

This aspect of the invention advantageously provides a new method for holding the edges of a sheet of material in a desired profile or shape, such that the desired shape penetrates along the length, and into the interior regions, of the sheet material.

Advantageously, this aspect of the invention provides said shape support: (i) using a light-weight material and structure; (ii) using rapid and cheap production and manufacturing processes;

(iii) providing high shape accuracy;

(iv) with the ability to rapidly alter the design profile or shape; and

(v) with simple, rapid and cheap methods of fixing and mounting the reflective sheet and the shape holding device together.

According to the third aspect of the invention there is provided a shape support for supporting a sheet material according to a desired profile, the shape support including: an elongate body portion, or 'rib'; and a plurality of spaced tabs extending from the elongate body portion, wherein the plurality of spaced tabs define a profile corresponding to the desired profile of the sheet material to be supported and are positioned such that an upper set of tabs engages an upper face of the sheet material and a lower set of tabs engages a lower face of the sheet material when the sheet material is supported by the shape support.

Again, although the shape support according to this aspect of the invention may find suitable use in a number of fields, it is primarily intended for use in solar energy concentrating assemblies. As such, the invention further provides solar energy concentrating assemblies which incorporate a shape support as described in the immediately preceding paragraph.

The material forming the body portion of the shape support may take any suitable form. Preferably, a sheet metal plate, either as a native metal material, or coated with protective metal layers or paint, or combinations of these is used. The thickness of the material of the elongate body portion may be selected based on the intended application, but generally is within the range of 0.5 to 2mm.

The plurality of tabs which extend from the elongate body portion may be provided in any suitable positioning, provided that they conform the sheet material, when so supported in the rib, to the desired profile, and provided that at least some of the tabs form the aforementioned upper set of tabs and others form the lower set of tabs. The tabs thereby preferably form an alternating pattern of upper and lower tabs, generally alternating between individual tabs, but also possibly alternating between sets of tabs.

The tabs may be punched through from either one or both sides of the sheet material, such that they form the alternating pattern, upper and lower tabs falling above and below the desired profile line-shape for the sheet material respectively.

The separation of the tabs either side of the desired profile line is sufficient to allow for the thickness of the sheet material to be supported. That is, the sheet material must fit between the upper tabs and lower tabs. Furthermore, the separation of the tabs along the desired profile is preferably such that adequate support is given to the supported sheet material to maintain the desired profile with minimal distortion of the supported sheet material between the tabs.

Preferably, the tabs are provided by "stamping" the material, for example metal, forming the body portion. In that case, the tabs are integral with the elongate body portion. It will however be appreciated that the tabs may alternatively be attached to the elongate body portion by suitable attachment means. This embodiment will not be dealt with in any detail here, preference being given to the so-called "stamped-tabs" formed by stamping the material of the elongate body portion.

In a particular embodiment of the third aspect of the invention, attachment between the shape support, also referred to herein as a "stamped-tab-rib", and the supported sheet material is facilitated by first punching or drilling small holes through an edge of the sheet material such that they are aligned to fall under openings of the tabs. When the sheet material is placed against the elongate body portion such that it falls along the desired profile between the tabs, and a locating hole is under a respective stamped tab, a small locating pin is inserted down through the opening of the tab above the hole, and also into the hole in the supported sheet material. In this way the pin locks or fastens the supported sheet material to the support. In a variation of the locking pin fastening system described above, attachment between the support and the sheet material may be accomplished by assembling the sheet material and the support together, and then plastically deforming the edge of the supported sheet which lies under a stamped tab, by the use of a punch or mandrel device, which pushes the metal of the supported sheet into the opening that exists between the stamped tab and the elongate body portion.

In another form of this aspect of the invention, a lower profile of the shape support, or stamped-tab-rib, above the surface of the supported sheet material can be achieved by a stamped and folded tab design. In this design, stamped tabs form the lower tabs for supporting the lower face of the sheet material, while the upper tabs extend from, or close to, an upper edge of the elongate body portion. Conveniently, the upper tabs are formed by folding over tabs that are integral with the elongate body portion such that they engage the upper face of the supported sheet material once it is in place on the lower stamped tabs. It will again be appreciated that the upper tabs may be provided by attachment to, or close to, the upper edge of the elongate body portion.

In a further variation of the third aspect of the invention, enhanced lateral structural stiffness may be achieved by providing folded edges around appropriate perimeters of the support. For example, the elongate body portion may include a lip or lips that extend along all or part of the longitudinal edges thereof to provide lateral support and stiffness. Such lips may advantageously be applied given a variety of rib profile shapes.

A more detailed description of embodiments of the third aspect of the invention will be provided with reference to the accompanying drawings hereafter.

According to a fourth aspect of the invention there is provided a solar energy concentrating assembly which includes one or more of the aforementioned laminated product of the first aspect of the invention, edge-moment rib according to the second aspect of the invention and shape support of the third aspect of the invention. Particularly, according to a specific embodiment of the present invention there is provided a solar energy concentrating assembly including:

(A) a reflective sheet material which includes a laminated product including a plurality of laminate components formed by: (i) placing sheet material of each laminate component in a curved mould;

(B) a pair of edge-moment ribs for engaging each end of the reflective sheet material and for applying torque to said reflective sheet material, each of said edge- moment ribs including: a body portion; an outer lip portion extending from the body portion; and an inner lip portion disposed beneath the outer lip portion; wherein each inner lip portion and outer lip portion extends along the length of the respective edge-moment rib, the opposing faces of the inner lip portion and the outer lip portion converging on each other from each end of the edge-moment rib towards the centre of the edge-moment rib; and

(C) a pair of shape supports for supporting each side of the reflective sheet material according to a desired profile, each of the shape support including: an elongate body portion; and a plurality of spaced tabs extending from the elongate body portion; wherein the plurality of spaced tabs define a profile corresponding to the desired profile of the reflective sheet material being supported and are positioned such that an upper set of tabs engages an upper face of the reflective sheet material and a lower set of tabs engages a lower face of the reflective sheet material.

Embodiments of the above described aspects of the invention will now be described in more detail with reference to the accompanying drawings in which: Figure 1 illustrates a mould having curved sections with differing radii of curvature over different sections of the mould;

Figure 2 illustrates laminate components held against the curved mould by a vacuum bag; Figure 3 illustrates a sheet of laminate held at its edges by edge-moment ribs according to one embodiment of the second aspect of the invention;

Figure 4 illustrates an edge-moment rib similar to that illustrated in Figure 3;

Figure 5 illustrates a profile view of an alternative embodiment of the edge-moment rib of the second aspect of the invention; Figure 6 illustrates a front view of one embodiment of a shape support or stamped- tab-rib;

Figure 7 illustrates a top view of the stamped-tab-rib of Figure 6;

Figure 8 illustrates stamped-tab-ribs and supported sheet structure;

Figure 9 illustrates a hole-punched sheet material being fitted to a stamped-tab-rib; Figure 10 illustrates a top view of the supported sheet and stamped-tab-rib showing locating hole;

Figure 11 illustrates the locating pin in place in the stamped-tab-rib;

Figure 12 illustrates a cut-away view of the locating pin in place;

Figure 13 illustrates a profile view of a stamped and folded tab rib; Figure 14 illustrates an isometric view of the stamped and folded tab rib of Figure

13 supporting a sheet material;

Figure 15 illustrates an isometric view of stamped-tab-ribs having folded edges or lips; and

Figure 16 illustrates a solar energy concentrating assembly including the sub- components of the various aspects of the invention.

Referring to Figure 1, a mould 10 is illustrated for use in the method of fabrication of the laminated product of the first aspect of the invention. The mould 10, which as previously described may be formed of any suitable material, has a trough-like shape including three portions having differing radii Rl, R2 and R3. The optimal values used for Rl, R2, R3, XI, X2, X3, etc. are determined by the specific dimensions and desired radii of curvature for the specific laminate being fabricated, are most advantageously determined by the use of Finite Element Analysis (FEA) software.

Referring to Figure 2, the components to be laminated 12 and 14 are placed in the mould 10 and a vacuum bag 16 placed over the top of the components 12, 14. The vacuum bag 16 is sealed to the mould 10 by vacuum seals 18.

On the application of a vacuum to the vacuum bag 16, pressure of the atmosphere outside the vacuum bag 16 causes the vacuum bag 16 to compress against the laminate components 12, 14, causing the laminate components 12, 14 to conform to the shape of the mould 10. Once sufficient conformity has been achieved, the laminate components 12, 14 are bonded together, generally by means of a fusable film (not shown) placed between the laminate components 12, 14. The vacuum is not removed until bonding of the laminate components 12, 14 is finalised.

Once the laminate components 12, 14 are bonded together, the vacuum is released and the final laminated product is removed from the mould 10.

Although the above discussion is primarily directed to the use of a vacuum to create the pre-curvature in the laminate components, it will be understood the invention may be modified such that alternative means provide the pre-curvature. For example, as discussed briefly above, a pressure bag may be applied to the laminate components when placed in the mould to bring the components into conformity with the mould surface.

By virtue of this aspect of the invention, it is possible to obtain intimate contact between a fusable film and the laminate components. Advantageously, this ensures that air bubbles are not trapped between the laminate components, the presence of air bubbles being undesirable for the final laminated product.

It should be noted that although the primary . area of the invention relates to the manufacture of laminated products for solar collectors, the first aspect of the invention may have a much broader application, such as in the preparation of laminated products for architectural and asthetic applications. Such alternative applications are considered to be within the scope of the first aspect of the present invention.

Referring to Figure 3, an edge-moment rib of the second aspect of the invention is illustrated. In one embodiment the edge-moment rib 30 includes an outer lip portion 31 and an inner lip portion 32 which include opposing faces 33 and 34 respectively. The inner lip portion 32 and outer lip portion 31 engage a sheet material 35 formed from a lower substrate laminate 16 and an upper substrate laminate 37.

According to this embodiment, the outer and inner lip portions 31, 32 are bonded together by a fastener 38 and extend along the edge of the material 35. In this case, the lower substrate 36 of the material 35. The elongate nature of the rib 30 is best illustrated with reference to Figure 4.

The edge-moment rib is applied to the edge of the material 35 and is used to apply a twisting moment to the edge of the material 35 as illustrated by curved arrows in Figure 3. This advantageously provides shape conformance to the material 35.

As illustrated in Figure 4, the gap between the opposing faces of the inner and outer lip portions is greater at each end 40 of the edge moment rib as compared to the centre 41 of the rib. As previously described, such an arrangement compensates for the non-uniform moment application due to material flexure of the edge-moment rib. The distance between the opposing faces may be for example, about 0.8mm at the centre point and possibly 0.8 to 2.0 mm at each end of the rib, depending on the fiexural rigidity of the material from which the rib is made.

An alternative embodiment of the edge-moment rib 50 is provided in Figure 5. According to this embodiment, the inner lip portion 52 is integral with and forms part of the body portion 53, the outer lip portion being joined to the inner lip portion by a joining portion

54. In this embodiment, once again the gap between the opposing faces of the outer and inner lip portions 51, 52 is greater at the edges of the edge-moment rib as compared with the centre of the rib. The inner and outer lips hold, and are used to apply a moment to the supported sheet material 55.

The edge-moment rib according to the second aspect of the invention advantageously provides a mechanism for applying torques or moments to the edge of a composite material, such as that used for a solar concentrator, to provide conformance to a desired shape. Furthermore, the edge-moment rib advantageously provides longitudinal rigidity along the length of the supported composite material, preventing sagging of the sheet of material as may be conventionally seen. Still f irther, the edge-moment rib of the second aspect of the invention provides a mechanism for the selective application of varying degrees of moment along the length of the rib. This effect being achieved by varying spacing between the opposing faces of the inner and outer portions of the rib such that moments can be applied more selectively in the centre of the rib as opposed to at the ends thereof.

Embodiments of the third aspect of the invention are illustrated in Figures 6 to 15. Referring firstly to Figure 6, a stamped-tab-rib 60 is illustrated which includes an elongate body portion 61 and a plurality of tabs 62,63 . The tabs 62,63 are divided into two sets, upper tabs 62 and lower tabs 63. The upper tabs 62 and lower tabs 63 are position so that they alternate on either side of a desired profile 64 for the sheet material to be supported.

As better illustrated in Figure 7, the tabs 62,63 are stamped out of the material of the elongate body portion 61 and are therefore integral with the elongate body portion 61. The tabs also define tab openings 65 between the tabs 62,63 and the elongate body portion 61.

When the sheet material 86 is supported by the stamped-tab-ribs 80 as illustrated in Figure 8, the upper tabs 82 engage an upper surface of the sheet material 86 while the lower tabs 83 engage a lower surface. The sheet material 86 is thereby conformed to a desired profile which is dictated by the profile of the tabs 82,83. In a particular embodiment, and as previously described and best illustrated in Figures 9 to 12, the sheet material 96 is preferably held securely in place relative to the stamped-tab- ribs. As illustrated in Figure 9, this may be achieved by providing holes 97 in the sheet material 96 which correspond to tab openings 95 between the tabs 92,93 and the elongate body portion 91. Thus, when the edge of the sheet material is flush against the elongate body portion 91, the holes 97 of the sheet material 96 are aligned under or above the tab openings 95, depending on whether the tab is an upper tab 92 or lower tab 93 respectively.

When the sheet material 96 is in position, locating pins 98 are positioned through the tab openings 95 and holes 97 to locate the sheet material 96 securely in place as best illustrated in Figures 11 and 12.

An alternative embodiment of the stamped-tab-rib according to the third aspect of the invention is illustrated in Figures 13 and 14. In this embodiment the upper stamped tabs previously illustrated in Figures 6 to 12 are replaced with folded tabs 132. The lower tabs 133 remain stamped tabs while the upper edge of the elongate body portion 131 follows the desired profile for the sheet material 136. It will be appreciated that the folded tabs could similarly replace the lower tabs 133 of the rib.

In order to provide structural stability and strength to the stamped-tab-rib, the elongate body portion 151 may be provided with folded edges or lips 159 as illustrated in Figure 15. The lips 159 extend along the longitudinal edges of the elongate body member 151, although it will be appreciated that a single lip may be provided on either the upper or lower longitudinal edge of the elongate body portion 151.

Figure 16 illustrates the sub-components of the various aspects of the invention completely assembled to form a solar energy concentrating assembly or solar reflector module. This includes a reflector 161 which generally corresponds to the sheet material here before described, a pair of edge-moment ribs 162 located at opposing ends of the reflector 161 and which can be employed to impart an edge-moment or twisting force to the reflector, and a pair of stamped-tab-ribs 163 located at either side of the reflector and supporting the reflector in a desired profile.

It will be appreciated that each preferred embodiment and alternative embodiment of each of the aspects of the invention as here before described apply to the assembly illustrated in Figure 16.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge in Australia.

Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications which fall within its spirit and scope. The invention also includes all the steps, features, compositions and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any two or more of said steps or features.

Claims

CLAIMS:

1. A method for the manufacture of a laminated product including a plurality of laminate components, the method including: (i) placing sheet material of each laminate component in a curved mould;

2. A method according to claim 1, wherein the mould is formed with a predetermined pre-curvature.

3. A method according to claim 1, wherein the radii of curvature, the placement and extent of the curved sections of the mould are predetermined based on the application desired for the finished laminated product.

4. A method according to claim 1, wherein the mould includes up to three different regions and radii of curvature per half of the mould.

5. A method according to claim 1, wherein the laminate is a glass on metal laminate including glass and metal laminate components.

6. A method according to claim 5, wherein the metal laminate component includes a metal sheet of a coated or uncoated iron or aluminium, or other metal sheet.

7. A method according to claim 6, wherein the metal sheet has a thickness of from about 0.4 - 1 mm.

8. A method according to claim 5, wherein a glass laminate component includes a mirror-backed glass sheet.

9. A method according to claim 8, wherein the glass sheet has a thickness of from about 0.6 - 1.0 mm.

10. A method according to claim 5, wherein a fusible film is placed between the glass and metal laminate components to facilitate bonding of the glass component to the metal component to form a rigid structure.

11. A method according to claim 10, wherein the fusible film has a thickness of from about 50 micron to 200 micron.

12. A method according to claim 10, wherein the bond line temperature of the fusible film is between about 80°C - 180°C.

13. A method according to claim 10, wherein the softening temperature of the fusible film is chosen such that it exceeds any expected temperatures the laminated product could experience in its designed exposure situations.

14. A method according to claim 1, wherein the laminate components include two glass components and a metal component located between said glass components.

15. A method according to claim 1, wherein the step of applying pressure to the laminate components includes sealing a vacuum bag over the laminate components, applying a vacuum to the vacuum bag such that pressure outside the bag causes the laminate components to conform to the shape of the mould and wherein the laminate components are bonded together while the vacuum is still being applied.

16. A method according to claim 15, wherein the vacuum applied to the vacuum bag is in the range of from about -40 kPa to -100 kPa.

17. A method according to claim 1, wherein the step of applying pressure includes bringing the laminate components into conformity with the mould surface using a pressure bag which forces the components down into the mould during filling of the bag.

18. An edge-moment rib for applying torque to a sheet of material including: a body portion; an outer lip portion extending from the body portion; and an inner lip portion disposed beneath the outer lip portion; wherein the inner lip portion and outer lip portion extend along the length of the edge-moment rib and in use engage an edge of the sheet material, the opposing faces of the inner lip portion and the outer lip portion converging on each other from each end of the edge-moment rib towards the centre of the edge-moment rib.

19. An edge-moment rib according to claim 18, wherein the outer lip portion is integral with the body portion and extends from an upper edge of the body portion.

20. An edge-moment rib according to claim 18, wherein the inner lip portion is provided by an attachment which is fastened to the body portion along the length of the body portion.

21. An edge-moment rib according to claim 18, wherein the inner lip portion forms part of the body portion and the outer lip portion is bridged with the inner lip portion by a joining portion of the rib.

22. A shape support for supporting a sheet material according to a desired profile, the shape support including: an elongate body portion; and a plurality of spaced tabs extending from the elongate body portion, wherein the plurality of spaced tabs define a profile corresponding to the desired profile of the sheet material to be supported and are positioned such that an upper set of tabs engages an upper face of the sheet material and a lower set of tabs engages a lower face of the sheet material when the sheet material is supported by the shape support.

23. A shape support according to claim 22, wherein the elongate body portion is formed from a sheet metal plate, either as a native metal material or coated with protective metal layers or paint, or combinations of these.

24. A shape support according to claim 22, wherein the thickness of the material of the elongate body portion is from about 0.5 to 2mm.

25. A shape support according to claim 22, wherein the plurality of tabs form an alternating pattern of upper and lower tabs alternating between individual tabs or alternating between sets of tabs.

26. A shape support according to claim 22, wherein the tabs are punched through from either one or both sides of the sheet material such that they form an alternating pattern, upper and lower tabs falling above and below the desired profile for the sheet material respectively.

27. A shape support according to claim 22, the separation of the tabs along the desired profile is such that adequate support is given to the supported sheet material to maintain the desired profile with minimal distortion of the supported sheet material between the tabs.

28. A shape support according to claim 22, wherein the lower tabs include stamped tabs which support the lower face of the sheet material and the upper tabs extend from, or close to, an upper edge of the elongate body portion.

29. A shape support according to claim 22, wherein the elongate body portion includes a lip or lips that extend along all or part of the longitudinal edges thereof to provide lateral support and stiffness.

30. A solar energy concentrating assembly including:

(A) a reflective sheet material which includes a laminated product including a plurality of laminate components formed by:

(i) placing sheet material of each laminate component in a curved mould; (ii) applying pressure to or causing pressure to applied to the laminate components such that the laminate components conform to the shape of the mould; and (iii) bonding the laminate components together while the pressure is still being applied or caused to be applied. (B) a pair of edge-moment ribs for engaging each end of the reflective sheet material and for applying torque to said reflective sheet material, each of said edge- moment ribs including: a body portion; an outer lip portion extending from the body portion; and an inner lip portion disposed beneath the outer lip portion; wherein each inner lip portion and outer lip portion extends along the length of the respective edge-moment rib, the opposing faces of the inner lip portion and the outer lip portion converging on each other from each end of the edge-moment rib towards the centre of the edge-moment rib; and (C) a pair of shape supports for supporting each side of the reflective sheet material according to a desired profile, each of the shape support including: an elongate body portion; and a plurality of spaced tabs extending from the elongate body portion; wherein the plurality of spaced tabs define a profile corresponding to the desired profile of the reflective sheet material being supported and are positioned such that an upper set of tabs engages an upper face of the reflective sheet material and a lower set of tabs engages a lower face of the reflective sheet material.

31. A laminated product formed by a method according to claim 1.

32. A solar energy concentrating assembling including any one or more of a laminated product according to claim 31, an edge-moment rib according to claim 18 and a shape support according to claim 22.