FIELD OF THE INVENTION

This invention relates to an assembly for sheet material, especially sheet panels for use in construction.

BACKGROUND OF THE INVENTION

Panel structures comprising sheet material and using supporting frames are employed in numerous situations, especially in the field of construction. For example, panel structures are used in the fabrication of windows, interior/exterior walls including curtain walling and partition walls, and doors. These structures may use any combination of glass, transparent, semi- transparent, translucent, and/or solid metal/polymer sheets.

The process of manufacturing such panel structures typically comprises providing material in large sheets (or panels) and cutting these sheets to a particular size that fits a given size of supporting frame. The sheets may then be fitted into the supporting frame(s) using various methods depending on the structure of the frame(s).

Numerous frames are known that accommodate the reception of single sheets of material. A panel structure comprising a single sheet of material supported by a frame is typically referred to as a 'single panelled' structure. More recently, frames have also been designed to accommodate more than one sheet of material. As a result, panel structures comprising two generally parallel sheets of material supported by a frame are now widely known and referred to as 'double panelled' structures. Similarly, 'triple panelled' structures have been demonstrated. Where the material supported in the frame is glass, the structure is generally referred to as "single glazed", "double glazed" or "triple glazed" structure.

For both single-panelled and double-panelled structures, the typical method of installation comprises fitting the sheet material to frame sections, commonly in the form of extruded articles that may be fitted along the peripheral edges of the sheet material. The resultant panel and frame structure may then be mounted in a corresponding receiving structure or framework, such as a wall or roof.

For double panelled structures, especially double-glazed windows, it is known to provide a spacer bar between the two sheets of material to ensure a correct gap between the sheets, and to seal the two sheets together to form a heat or sound barrier (i.e. a sealed unit). Such spacer bars have also been provided with perforations containing desiccant material, which absorb moisture in the trapped air to prevent condensation forming in the space between the sheets. Air can also be replaced with an inert gas such as argon to further improve insulation.

The method steps associated with the manufacture and installation of such panel structures, for example cutting, handling, edge treating, carrying, fixing and installation, in addition to the long term performance of such structures, provide many difficulties. In particular, as a result of the physical attributes of typical panel structures, such as fragility and weight, numerous problems arise. These problems can create deficiencies in, for example, quality, strength, durability and air/water-tightness, and minimising such deficiencies results in additional manufacturing/installation complexity and cost.

Furthermore, panels structures (and their component sheets) used in civil construction may be subjected to sudden impact forces of considerable magnitude or unwanted attempts to remove the sheet material from the supporting framework.

It is, therefore, desirable to realise a supporting frame assembly for sheet material that provides for reduced installation/manufacturing complexity and cost. Furthermore, it is also desirable for such frame assembly to provide significantly improved levels of strength and resistance against impact forces (for example bomb blasts) and/or unwanted attempts to remove the sheet material. SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a frame assembly comprising: a panel defined by opposing surfaces, and one or more peripheral edges extending between the opposing surfaces, the opposing surfaces terminating at the one or more peripheral edges; and an outer frame section for receiving the panel, the outer frame section comprising a projection, wherein the panel comprises a recess formed in a first surface of the panel, the recess being adapted to receive the projection of the outer frame section, whereby the recess cooperates with the received projection to restrict movement of the received panel relative to the outer frame section.

Thus, the invention provides a frame assembly for sheet material that reduces installation/manufacturing complexity and cost. Furthermore, a frame assembly according to the invention provides improved levels of resistance against sudden impact forces and/or unwanted attempts to remove or break through the sheet material. By forming a recess in a face of the panel, a cross- sectional shape of the panel can be provided wherein the cross-sectional shape is designed to create, form or otherwise define a space for receiving a projection of an outer frame section. Thus, the recess and received projection may cooperate to hinder relative lateral and/or vertical movement. In this way, lateral and vertical movement of the panel (e.g. sheet material) may be hindered or prevented when the outer frame section receives the panel.

It is also noted that the recess may increase an available area for bonding to the panel or sheet material than would otherwise be available (e.g. if no recess was provided and the outer frame bonded to the surface of the panel).

Proposed concepts may also help to eliminate or relieve a need for specialist installation personnel. Further, embodiments may avoid the need to apply silicone between the sheet material and the frame, enabling installation time reduced. Eliminating a need for silicone application also addresses the problem that silicone application can typically only be done in dry and warm conditions. The proposed invention provides a system which moves quality requirements towards the manufacturing stage(s), rather than relying on unpredictable or variable results due to the application of 'wet' products on site. For example, a recess may be formed in a panel in a controlled manufacturing environment (which may have specialist equipment available for example) so as to facilitate accurate and high-quality products that are adapted and ready to be installed into (e.g. received by) outer frame sections.

The frame assembly may be fully "bi-directional" in its performance. That is, it may be able to withstand a bomb blast in both directions (it should be noted here that the shock waves caused by bomb blasts do generate inward and outward forces on a window).

With some embodiments, frames can be subsequently adapted to accommodate changes of sheet material thickness or change in the number of panels of sheet material without having to remove the frames from the wall, and with full access from the inside of the building.

The recess may be located proximate (e.g. near, neighbouring, close to) a peripheral edge of the panel, such as in a peripheral portion of the first surface. Positioning the recess at, near or close to a peripheral edge of the panel facilitates reception of an outer frame section at or around the edge of the panel. For example, outer frame sections may be fitted around the edges of the panel leaving a large central portion of the surface(s) of the panel uncovered (i.e. exposed).

By way of example, there may be provided a panel (e.g. polycarbonate panel) that is equipped or formed with a groove around the border of the panel. The groove may be adapted to engage with a protruding feature of an outer frame section (e.g. a support frame) so as to retain the panel in the frame against the action of loads acting in the plane of the panel. The groove dimensions may depend on factors such as the severity of a blast which the panel must resist, the materials/properties of the panel and/or the design of the frame. However, by way of example, it may be preferable to arrange the groove to be 5mm deep by 10mm wide, with the inner body of the groove being 37.5mm from the edge of the glazing panel. It may be preferable to make the radii of the edges of the groove in the region of 1 mm. The groove may be machined, moulded or cast into the panel or introduced by any other suitable manufacturing process.

Preferably, the recess and the projection of the outer frame section are adapted to have complementary or interlocking geometries.

In another preferred version, the recess is larger than the received projection in at least one dimension by a tolerance value. By way of example, the tolerance value may be greater than or equal to 5 mm, and may, in some embodiments, be greater than or equal to 10 mm. By being larger than the received projection, the recess may cater for manufacturing and/or installation variations. Also, room for expansion of the material(s) may be provided.

The cross-sectional shape of the outer frame section may be substantially U-shaped. To enhance a frictional grip, there may be roughened or serrated surfaces on abutting faces of the panel and outer frame section. Such serration could be fine or delicately indented/patterned, and the faces may have matching indentations.

In an embodiment, the recess may comprise a groove, or series of grooves, adapted receive the projection, or projections, of the outer frame section, the projection comprising a tongue or tongues. In this way, a simple matching or mating geometry may be employed so as to enable the panel and outer frame section to cooperate with each other.

The outer frame section may comprise a pocket or recess adapted to receive one or more panels, and the cross-sectional shape of the pocket may be adapted to substantially match that of the one or more panels. Such an arrangement may reduce the ability of a panel to be levered out of the internal space (e.g. pocket or recess) within which the outer frame section receives the panel(s). To lever a panel from its assembled position, one would have to prise apart the panel from the outer frame section along its entire perimeter. Such an action is seriously impeded since any rigid implement used to provide a levering force would be unable to 'wrap' around the perimeter of the panel in order to separate it from the outer frame section.

The frame assembly may be a window with single frame, a single composite window carrying more than one sheet material, a curtain wall facade or door frame assembly and the sheet material may be at least semi- transparent. There may be thus be provided a multi-panelled assembly. The use may be in a wall, floor or overhead assembly. Further, proposed concepts may enable a sealed unit to be formed which is desirable for heat and sound insulation. It is envisaged that adapting an outer frame section to receive two or three parallel sheets or panels will be of particular advantage. Further to this, some panels may also be provided with moisture absorbing means therebetween. In this way, condensation can be prevented from forming in the space between sheets/panels.

The outer frame section may be made of aluminium, steel, UPVC, fibre- reinforced cement, plastic or other polymer material.

An embodiment may further comprise: a second panel defined by opposing surfaces, and one or more peripheral edges extending between the opposing surfaces, the opposing surfaces terminating at the one or more peripheral edges, wherein the outer frame section comprises a second projection. Further, the second panel may comprise a recess formed in a second surface of the second panel, the recess being adapted to receive the second projection of the outer frame section, whereby the recess of the second panel may cooperate with the received second projection to restrict movement of the received second panel relative to the outer frame section.

In addition, the frame assembly may have the ability to accommodate new (replacement) sealed structures of different sizes (length or width). For example, embodiments may cater for the insertion of ballistic resistant or break- in resistant sheets of material in straight-forward manner. Such additional sheets of material may be made from Polycarbonate for example.

The cross-sectional shape of the outer frame section may be substantially U-shaped. However, the cross-sectional shape of the outer frame section may instead be selected from circular, regular polygonal and irregular polygonal.

A window or door frame assembly may be provided by the invention. Thus, in such an assembly the sheet material may be glass, clear, opaque, translucent or otherwise. The sheet material may be a panel of one material or sections of different material, placed side by side in one frame, or placed above or below in any combination. Alternatively, the frame assembly may include blinds.

By way of example, the outer frame sections may be made of aluminium, steel or other metals. Alternatively, they may be formed from UPVC or other plastics or a polymer material. Of course, the outer frame sections may also be formed from any combination of these materials.

Although the above discussion might suggest that the frame assembly is made up of section lengths fitted around the sides of a panel, with corner pieces potentially completing the inner frame, the outer frame sections could have mitred ends if so desired. Furthermore, the outer frame sections could extend around a corner of the sheet material so that in one embodiment the outer frame is made up of four L-shaped outer frame sections (that may be thought of as corner pieces). Thus, if a corner piece extends along a significant length of the sheet material, then functionally it may be considered as an "outer frame section" within the terms of the invention as defined herein.

Linked to the above assembly, according to yet another aspect of the invention, there is provided a panel for a frame assembly for sheet material, the panel being defined by opposing surfaces, and one or more peripheral edges extending between the opposing surfaces, the opposing surfaces terminating at the one or more peripheral edges, wherein the panel comprises a recess formed in a first surface of the panel, the recess being adapted to receive a projection of an outer frame section of the frame assembly, whereby the recess cooperates with the received projection to restrict movement of the received panel relative to the outer frame section. Thus, there may be provided an individual panel or sheet of rigid material having a recess formed in a planar surface, preferably near a peripheral edge of the panel or sheet material. By being provided with a recess, a panel may be adapted to provide a particular cross-sectional shape. The cross-sectional shape may be designed so as to provide a geometry or shape that is adapted to substantially match or complement that of an outer frame section. For example, the recess may be adapted to receive a respective projection of an outer frame section when the panel and outer frame section are brought or fitted together. By receiving the projection, the matching or complementary shapes of the recess and the projection may cooperate so as to restrict, hinder or prevent movement of the panel relative to the outer frame section.

Thus, the recess of the panel and the projection of the outer frame section may be adapted to have complementary or interlocking geometries. Substantially matching geometries may thus be employed for the recess and outer frame sections so as to form an interconnection which hinders or prevents a panel from being removed from the outer frame section.

Also, the recess of the inner frame section may be larger than the received projection in at least one dimension by a tolerance value, and preferably the tolerance value may be greater than or equal to 5 mm.

The recess may be located proximate a peripheral edge of the panel. An embodiment may comprise a groove which is adapted to receive the projection of the outer frame section, the projection comprising a tongue.

According to another aspect of the invention, there is provided a method of constructing a framed panel structure having a panel, wherein a panel comprises a panel defined by opposing surfaces, and one or more peripheral edges extending between the opposing surfaces, the opposing surfaces terminating at the one or more peripheral edges, and wherein the method comprises: receiving, in an outer frame section, the panel such that a formed in a first surface of the panel receives a projection of the outer frame section, whereby the recess cooperates with the received projection to restrict movement of the received panel relative to the outer frame section.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of the invention will now be described in detail with reference to the accompanying drawings, in which:

Figure 1 illustrates a cross-sectional view of a frame assembly according to an embodiment, wherein the left-hand side of the diagram is the external/outside facing side;

Figure 2 illustrates a cross-sectional view of a frame assembly according to an embodiment, wherein the left-hand side of the diagram is the external/outside facing side; and

Figure 3 illustrates a modification to the embodiment of Figure 2; and Figure 4 illustrates a modification to the embodiment of Figure 3.

DETAILED DESCSRIPTION

The following description provides a context for the description of elements and functionality of the invention and of how elements of the invention can be implemented.

It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

In the context of the present application, where embodiments of the present invention constitute a method, it should be understood that such a method is a process for execution by a computer, i.e. is a computer- implementable method. The various steps of the method therefore reflect various parts of a computer program, e.g. various parts of one or more algorithms.

Proposed are concepts for reducing installation/manufacturing complexity and cost of a frame assembly for sheet material. The invention is at least partly based on the insight that a surface of sheet material (e.g. panel) may be formed with a recess of a particular shape so as to provide a predetermined/desired cross-sectional shape. The resultant cross-sectional shape of the sheet material may be designed to receive a projection of an outer frame section. In other words, the resultant cross- sectional shape of the sheet material (with recess formed therein) may have a geometry that compliments or matches that of an outer frame section. The matching or complementary shapes may then cooperate to restrict or prevent relative movement of the sheet material and the outer frame section. In this way, an outer frame section may be applied to sheet material to securely position and hold the sheet material within a frame.

The invention may thus employ the concept that a substantially flat, planar surface of sheet material can be processed, formed or machined to have a recess or space for providing an interlocking arrangement.

Illustrative embodiments may be utilised in many different types of frame assemblies, including window frames, curtain wall, roof glazing, door frames, partitions, barriers, etc.

Referring to Figure 1 , there is depicted a frame assembly 10 according to an embodiment of the invention. Here, the frame assembly is for securely holding two panels 12, 14 of sheet material in a substantially parallel arrangement. Also, the left-hand side of the diagram is assumed to be an external/outside facing side.

For the avoidance of doubt, and for an improved understanding, reference to a panel, sheet panel, or single sheet/panel of sheet material should be taken to refer to a panel of sheet material which comprises a body (or panel) defined by opposing surfaces, and one or more peripheral edges extending between the opposing surfaces, the opposing surfaces terminating at the one or more peripheral edges. The peripheral edge(s) therefore define the outer perimeter of the flat body (or panel). Reference to a peripheral portion of a surface of a sheet panel (or panel of sheet material) should therefore be taken to refer to a portion of the surface that is situated adjacent a peripheral edge of the sheet panel. In this way, being located proximate a peripheral edge (for example, in a peripheral portion of a surface) of a panel will therefore be understood as being located at or near the edge of the surface (e.g. only separated from the peripheral edge by a small distance relative to the size of the panel, e.g. less than 25cm, preferably less than 10 cm, even more preferably less than 5 cm, and yet more preferably less than 2cm). Although it is envisaged the that opposing surfaces may be substantially flat or planar, it that embodiments are foreseen wherein the opposing surfaces are not planar but are instead curved, convex, concave or the like.

A first panel 12 comprises a sheet of polycarbonate 12 having a, outwardly facing first planar surface 12A. A second panel 14 comprises a sheet of glass 14.

First 16 and second 18 outer frame sections are provided for receiving the first 12 and second 14 panels of sheet material.

The first outer frame section 16 comprises a projection 20 extending inwardly towards the second outer frame section 18. In this example, the projection 20 is in the form of an inwardly projecting lip 20.

The first panel 12 comprises a recess 21 formed in the first planar surface 12A. The recess 21 is shaped such that it defines a space 21 adapted to receive the projection 20 of the first outer frame section 16, whereby the recess 21 cooperates with the received projection 20 to restrict movement of the received first panel 12 relative to the first outer frame section 16.

More specifically, in the embodiment of Figure 1 , the first panel 12 comprises a groove 21 in its first planar surface 12A. The groove 21 is located in a peripheral portion 15of the first panel 12 and formed along the longitudinal length of the first panel 12. When received in the groove, the lip 20 of the first outer frame section 16 fits inside the groove 21 . Thus, when the first panel 12 is received by the first outer frame section 16, the lip 20 prevents the first panel

12 from being lifted out of the first outer frame section 16.

In this example, the recess 21 and the projection 20 of the first outer frame section 16 comprise substantially complementary (i.e. matching) or interlocking geometries. However, it is noted that, in this example, the recess 21 of the first panel 12 is adapted to be larger than the received projection 20 in at least one dimension. More specifically, in the embodiment of Figure 1 , the recess 21 of the first panel 12 is larger than the received projection 21 in the vertical direction by around 5mm. This difference in dimension caters for manufacturing tolerances and/or installation variations by providing extra vertical room for the projection 20 to fit in the recess 21 . Of course, it will be understood that other values of the size difference may be employed, such as about 10mm or about 15mm for example, and the size difference need not be in the vertical direction (e.g. it may be in the horizontal direction, depth direction, or any combination of thereof). The additional space provided by making the recess 21 to be larger than the received projection 20 may additionally (or alternatively) be adapted to cater for gradual or sudden expansion of components (such as the outer frame sections and/or the panels of sheet material for example).

In the example embodiment of Figure 1 , the second outer frame section 18 is adapted to be brought towards the first outer frame section 16 so as to capture (e.g. sandwich or trap) the first panel 12 therebetween. To enhance a frictional grip, there may be roughened or serrated surfaces on abutting faces of the first panel 12 and the outer frame sections 16,18. Such serration could be fine or delicately indented/patterned, and the faces may have matching indentations.

It is also noted the that the second outer frame section 18 is formed with a seat or elbow portion 22 onto which the second panel 14 is received.

Thus, it will be understood that the cross-sectional shape of the outer frame sections 16, 18 combine to define a pocket adapted to receive the first 12 and second 14 panel. Furthermore, the inner cross-sectional shape of the pocket (e.g. the cross-sectional shape defined by the inner or inwardly-facing surfaces of the outer frame portions 16,18) is adapted to substantially match the outer cross-sectional shape of the first and second panels with a spacer element 24 situated therebetween (e.g. the cross-sectional shape defined by the outer or outwardly-facing surfaces of the combined panels 12,14 and spacer element 24).

It may be preferable, although not necessarily essential (e.g. depending on application), for the structural spacer element 24 to be designed to withstand high loads (e.g. to withstand the same loads as the frame assembly). By way of example only, the spacer element 24 may be formed from monolithic material that is chosen for its compressive strength and low heat conductivity properties. Alternatively, the spacer bar may be formed from a composite material that is designed and/or chosen so as to provide the required compressive strength and heat conductivity properties.

For instance, the spacer bar may be made of a range of materials which provide a structural strength of at least 90 N per mm of length and a low thermal conductivity to minimise thermal bridging. Materials such as polycarbonate, ABS or other thermoplastics, in solid or cellular cross-sectional form could be used. For a typical thermoplastic, the outer shape of the cross section could be basically rectangular and similar in dimension to the amount of overlap between the sheet material and frame in the plane of the sheet, i.e. 37.5mm. Normal to the plane of the sheet, the dimension could be 16mm approximately, so as to optimise the thermal resistivity of the gas-filled gap between the sheets 12, 14. In the case of a 37.5mm x 16mm spacer, at least 25% of the cross section should preferably comprise columns spanning the 16mm direction.

Such an arrangement may reduce the ability of the first panel 12 to be levered out of the internal space (e.g. the pocket or recess) of the combined outer frame sections 16,18. To lever the first panel 12 from its assembled arrangement (as depicted in Figure 1 ), one would have to prise apart the first panel 12 from the first outer frame section 16 along its perimeter. Such an action is seriously impeded since any rigid implement used to provide a levering force would be unable to 'wrap' around the perimeter of the first panel 12 in order to separate it from the first outer frame section 16. As mentioned in the preceding paragraph, provided between the first 12 and second 14 panels of sheet material is an elongated structural spacer element 24. This helps to maintain the separation between the panels 12, 14 of sheet material and ensures that the panels 12, 14 are held locked within the outer frame sections 16, 18.

By way of example, the frame assembly of Figure 1 may be employed in a window or door frame assembly and the both panels 12, 14 may be at least semi-transparent, partially opaque, or translucent. There may be thus be provided a multi-panelled assembly window or door frame assembly. Embodiments may be employed in other assemblies, such as barriers, curtain walling, roof tiling, roof lights, ceilings, suspended ceilings, partition walls, etc.

Further, proposed concepts may enable a sealed unit to be formed which is desirable for heat and sound insulation. It is envisaged that adapting one or more outer frame sections to receive two or three parallel sheets or panels (with a recess formed in at least one of the sheets/panels) will be of particular advantage. However, proposed concepts are equally applicable to adapting an outer frame section to receive a single sheet or panel such that a projection of the outer frame section cooperates with a recess formed in the sheet/panel.

It is noted that for embodiments adapted to receive two, three or more sheets or panels, the sheets/panels may be provided with moisture absorbing means therebetween. In this way, condensation can be prevented from forming in the space between sheets/panels. Also, a spacer or spacing element may be provided between adjacent sheets/panels for assisting and/or maintaining the correct positioning and separation of the sheet material. The moisture absorbing means may be provided in a perforated chamber filled with desiccant or desiccant foam tape formed in such a spacer or spacing element.

Although the embodiment of Figure 1 has been described as comprising two outer frame sections that are adapted to capture a panel therebetween, other embodiments may employ alternative arrangements. For example, referring to Figure 2, there is depicted a frame assembly 30 according to an alternative embodiment. The embodiment is similar to that to Figure 1 except that the cross-section comprises a single outer frame section 32 having a substantially U-shaped cross-sectional shape. By way of example only, the outer frame 32 section may be made of aluminium, steel, UPVC, plastic or other polymer material.

The first 12 and second 14 panels are the same as that of the embodiment of Figure 1 . Accordingly, to avoid unnecessary repetition, description of the first 12 and second 14 panels is hereby omitted.

The outer frame section 32 comprises a projection 20 extending inwardly towards its opposing side. As with the example of Figure 1 , the projection 20 of the embodiment of Figure 2 is in the form of an inwardly projecting lip 20.

The first panel 12 comprises a recess 21 formed in the first planar surface 12A. The recess 21 is shaped such that it defines a space 21 adapted to receive the projection 20 of the outer frame section 32, whereby the recess 21 cooperates with the received projection 20 to restrict movement of the received first panel 12 relative to the outer frame section 32. More specifically, in the embodiment of Figure 2, the first panel 12 comprises a groove 21 in its first planar surface 12A. The groove 21 is formed along the longitudinal length of the first panel 12. When received in the groove, the lip 20 of the outer frame section 32 fits inside the groove 21 . Thus, when the first panel 12 is received by the outer frame section 32, the lip 20 prevents the first panel 12 from being lifted out of the outer frame section 32.

As with the embodiment of Figure 1 , provided between the first 12 and second 14 panels of sheet material is an elongated structural spacer element 24. This helps to maintain the separation between the panels 12,14 of sheet material and ensures that the panels 12,14 are held locked within the outer frame sections 16, 18. Directly below the spacer element 24, and extending between the first 12 and second 14 panels of sheet material there is provided a seal element 34 which is adapted to form a sealed connection between the first 12 and second 14 panels (so as to prevent water ingress for example). Sandwiched between the bottom (i.e. downwardly facing edges of the inner frame sections 16, 18 and panels 12, 14) and the outer frame section 32 is a packer 36. The packer 36 assists correct placement of the panels 12,14 within the outer frame section 32 and may also cater for manufacturing tolerances and/or material expansion. The packer 36 need not be continuous.

Although the embodiment of Figure 2 has been described as comprising an outer frame section having a substantially U-shaped cross-sectional shape, it should be understood that, in other embodiments, the cross-sectional shape of the outer frame section may be selected from circular, regular polygonal and irregular polygonal.

In addition, the frame assembly has the ability to accommodate new or replacement sealed structures of different sizes (length or width). For example, embodiments may cater for the insertion of ballistic resistant or break-in resistant sheets of material in straight-forward manner. Such additional sheets of material may be made from Polycarbonate for example.

Although the embodiment of Figure 2 has been described as being adapted to cooperate with one panel having a recess formed therein, other embodiments may cater for more than one panel having a recess. For example, referring to Figure 3, there is depicted a modification to the frame assembly of Figure 2.

The frame assembly 40 of Figure 3 caters for a second panel 14 having a recess 51 formed in an outwardly facing planar surface 14A. The recess 51 is shaped such that it defines a space 51 adapted to receive a respective projection 50 of the outer frame section 32, whereby the recess 51 cooperates with the received projection 50 to restrict movement of the received second panel 14 relative to the outer frame section 32.

Thus, the outer frame section 32 comprises first 20 and second 50 projections extending inwardly towards each other. The projections 20,50 of the embodiment of Figure 3 are in the form of an inwardly projecting lip 20.

In this example, the recesses 21 ,51 and the respective projections 20,50 of the outer frame section 32 comprise substantially complementary (i.e. matching) or interlocking geometries. Thus, it will be understood that the cross- sectional shape of the outer frame section 32 defines a pocket adapted to receive the first 12 and second 14 panels. Furthermore, the inner cross- sectional shape of the pocket (e.g. the cross-sectional shape defined by the inner or inwardly-facing surfaces of the outer frame portion 32) is adapted to substantially match the outer cross-sectional shape of the first 12 and second 14 panels with a spacer element 24 situated therebetween (e.g. the cross- sectional shape defined by the outer or outwardly-facing surfaces 12A, 14A of the combined panels 12, 14 and spacer element 24). Such an arrangement may reduce the ability of the first 12 and second 14 panels to be levered out of the internal space (e.g. the pocket or recess) of the outer frame section 32.

The first panel 12 comprises a recess 21 formed in the first planar surface 12A. The recess 21 is shaped such that it defines a space 21 adapted to receive the projection 20 of the outer frame section 32, whereby the recess 21 cooperates with the received projection 20 to restrict movement of the received first panel 12 relative to the outer frame section 32. More specifically, in the embodiment of Figure 2, the first panel 12 comprises a groove 21 in its first planar surface 12A. The groove 21 is formed along the longitudinal length of the first panel 12. When received in the groove, the lip 20 of the outer frame section 32 fits inside the groove 21 . Thus, when the first panel 12 is received by the outer frame section 32, the lip 20 prevents the first panel 12 from being lifted out of the outer frame section 32.

Although the above description may suggest that a completed frame assembly may be made up of section lengths fitted around the sides of a panel, with corner pieces potentially completing the frame, the outer frame section(s) could have mitred ends if so desired. Furthermore, the outer frame sections could extend around a corner of the sheet material so that in one embodiment the outer frame is made up of four L-shaped outer frame sections (that may be thought of as corner pieces). Thus, if a corner piece extends along a significant length of the sheet material, then functionally it may be considered as an "outer frame section" within the terms of the invention as defined herein. To provide suitable strength and allow for ease of manufacture, for example by extrusion, an outer frame section of an embodiment may be made of aluminium, steel, UPVC or other plastics or polymer material. Such materials are purely exemplary since an inner frame section may be formed from any suitable material.

By way of further example, in the illustrated embodiments, the outer frame sections are each formed from aluminium and each have (maximum) thickness of between 2mm - 50mm. Of course, it will be appreciated that the outer frame sections may be of greater, lesser or varying thickness in alternative embodiments.

Although the embodiments have been depicted and described as employing (somewhat rectangular) grooves for receiving a lip portion of an outer frame section, it is to be understood that other embodiments may employ other combinations of matching or complementary geometries. For example, in an alternative embodiment, a recess may have a substantially triangular cross- section shape and/or may be curved (i.e. non-linear) along its longitudinal length.

Further, although the embodiment of Figure 3 has been depicted and described as employing a single outer frame section 32 that is formed as a single component (e.g. a single elongate extruded member having a generally U-shaped cross-sectional shape), it is to be understood that other embodiments may employ an outer frame section that is formed from two or more components that are brought together so as to capture the panel(s) therebetween. In other words, a proposed embodiment may comprise a modification to that depicted in Figure 3, the outer frame section is formed from first and second outer frame section portions.

By way of example, referring to Figure 4, there is depicted a modification to the embodiment of Figure 3, wherein the outer frame section 32 comprises a first outer frame sub-section 32i and a second outer frame sub-section 32 ₂ .

Each of the first 32i and second 32 ₂ outer frame sub-sections comprise elongate extruded members. In this example, the first outer frame sub-section 32i has a generally L-shaped cross-sectional shape (with a projection 20 extending along the longitudinal length of the first outer frame sub-section 32i). Similarly, the second outer frame sub-section 32 ₂ has a generally L-shaped cross-sectional shape (with a projection 50 extending along the longitudinal length of the second outer frame sub-section 32 ₂ ).

As depicted in Figure 4, the first 32i and second 32 ₂ outer frame subsections are brought together so as to form a combined outer frame section 32 having a generally U-shaped cross-section shape and to capture the first 12 and second 14 panels.

Thus, in the embodiment of Figure 4, the first outer frame sub-section

32i receives the first 12 and second 14 panels of sheet material. The second outer frame sub-section 32 ₂ is also for receiving the panels of sheet material. Means to connect the first 32i and second 32 ₂ outer frame sub-sections together are provided (such as locking geometries of the inner frame sections and the outer frame sub-sections; frictional contact; bonding/adhesives; compression clamping, etc.). The first 32i and second 32 ₂ outer frame subsections together define a space for receiving the panel 12, 14.

In this example, the first 32i and second 32 ₂ outer frame sub-sections may be adapted to apply a compressive force to the first 12 and second 14 panels so as to clamp the panels 12,14 and substantially prevent movement of the panels 12, 14 relative to the first 32i and second 32 ₂ outer frame subsections. However, it is to be understood that in other embodiments a clamping pressure (e.g. compressive force) need not be used as the holding means.

There is also provided a method of constructing a framed panel structure having one or plural parallel panels. The method of constructing may comprise the step of receiving, in an outer frame section, the panel such that a recess formed in a first planar surface of the panel receives a projection of the outer frame section, whereby the recess cooperates with the received projection to restrict movement of the received panel relative to the outer frame section. For example, the panel(s) is/are positioned (e.g. inserted or introduced) in an outer frame such that a recess formed in the panel(s) receives a respective projection of the outer frame.

The reader will appreciate that, in proposed embodiment, the outer frame section and recess(s) in the sheet material cooperate to retain the sheet material (e.g. panel). Such cooperation of the sheet material and outer frame thus restricts movement of the sheet material, and this restriction may be in the lateral direction and/or vertical direction. Also, more the one recess may be formed in a surface of a panel of sheet material. For example, an arrangement of parallel grooves may be formed in a surface panel, each groove being adapted to receive a respective projection of an outer frame section.