Sheet assemblies and sheets therefor
BACKGROUND OF THE INVENTION 
     This invention relates to sheet assemblies and sheets therefor. 
     In the construction of large substantially rigid panels it is frequently desirable to produce large areas with a minimum of bracing elements. Such panels can be made of any suitable material although metals such as aluminum or steel or their alloys are preferred. Such large panels find application, for example, in the construction of van bodies, domestic buildings, caravans and road signs. It is desirable that such large panels should be capable of ready assembly from smaller sheets which can be easily and economically connected together to provide a panel of the desired size and rigidity. 
     BRIEF SUMMARY OF INVENTION 
     The invention broadly stated provides a fabricated rigid sheet profiled for engagement with an adjacent similar sheet for assembly as a panel, the sheet being of substantially rectangular shape and having a first flange extending rearwardly of one longitudinal edge and a second flange extending rearwardly of a longitudinal edge opposed to said one longitudinal edge, at least one opening in one of the first and second flanges and securing means associated with the other of said first and second flanges for engagement at said opening of the adjacent similar sheet with the first flange of one sheet in supporting engagement with the second flange of the adjacent similar sheet. 
     According to one aspect of the present invention, there is provided a fabricated rigid sheet profiled for engagement with an adjacent similar sheet for assembly as a panel, the sheet being of substantially rectangular shape and having a first flange extending rearwardly of one longitudinal edge to which it is connected by a first fold providing a first U-shaped channel and a second flange extending rearwardly of a second longitudinal edge opposed to said one longitudinal edge, the second flange being connected to the second longitudinal edge by a second fold providing a second U-shaped channel, the first and second channels being rearward of the general plane of the sheet and opening in the same direction and being so dimensioned that the first fold is engageable within the second fold of an adjacent similar sheet to locate the adjacent sheets with the first flange in supporting engagement with the second flange of the adjacent similar sheet, at least one opening in the wall of one of the first and second folds and securing means associated with the other of said first and second folds for engagement in said opening of the adjacent similar sheet. 
     The opening or openings can be formed in the wall of the first fold with the securing means formed as projections extending inwardly of the second fold of the adjacent sheet and into the opening or openings in the first fold. Such projections may be struck out from the material of the second fold and inwardly thereof. Such projections may be formed in situ when the adjacent sheets are engaged or may be preformed. 
     It is preferred, however, that the securing means be in the form of projections extending outwardly from the first fold for engagement with an aperture or apertures in the wall of the second fold of the adjacent similar sheet. 
     According to a preferred embodiment of the invention, the rear wall of the first fold is formed with a plurality of spaced apertures along the length of the fold, the rear wall of the second fold is formed with a plurality of correspondingly spaced apertures along the length thereof so that the apertures in the second fold register with the apertures of the first fold of an adjacent similar sheet and the securing means comprises a separate strip dimensioned to be received within the first fold and formed with projections spaced at intervals to correspond with the spacing between the apertures in the first and second folds and arranged to extend through the apertures of the first fold into the apertures of the second fold of an adjacent engaged similar sheet. 
     The invention also extends to a plurality of sheets according to any one of the preceding four paragraphs with the first fold of one sheet engaged within the second fold of an adjacent similar sheet and the securing means engaged in the opening. 
     According to another aspect of the present invention there is provided a panel composed of a plurality of adjacent similar fabricated rigid sheets each being of substantially rectangular shape and formed with a first flange extending rearwardly of one longitudinal edge to which it is connected by a first fold providing a first U-shaped channel and a second flange extending rearwardly of a second longitudinal edge opposed to said one longitudinal edge, the second flange being connected to the second longitudinal edge by a second fold providing a second U-shaped channel, the first and second channels being rearward of the general plane of the sheet and opening in the same direction, the first fold of one sheet being engaged within the second fold of the adjacent similar sheet with the first flange of the one sheet in supporting engagement with the second flange of the adjacent similar sheet, openings in the wall of one of the first and second folds and securing means associated with the other of the first and second folds and engaged in said openings. 
     Preferably, the openings are formed in the rear walls of both the first and second folds and are in register and the securing means comprises a securing strip received within the first fold and formed with projections engaged in the apertures of the engaged first and second folds of adjacent similar sheet. 
    
    
     Embodiments of the invention will now be described by way of example, reference being made to the accompanying drawings in which: 
     FIG. 1 is a fragmentary perspective view showing two sheets according to the invention engaged to form a panel, 
     FIG. 2 is a fragmentary enlarged view showing the two sheets of FIG. 1 ready for engagement to form a panel, 
     FIG. 3 is a section taken on the line III--III of FIG. 2, 
     FIG. 4 is a fragmentary perspective view of a preferred form of sheet according to the invention with associated securing means, 
     FIG. 5 is a fragmentary perspective view showing two sheets according to FIG. 1 secured together, and 
     FIG. 6 is a fragmentary elevational view of the securing means shown in FIGS. 4 and 5, 
     FIG. 7 is a view similar to FIG. 1 illustrating a modified sheet, 
     FIG. 8 is an enlarged fragmentary view illustrating a modification, 
     FIG. 9 is a view taken on the line IX--IX of FIG. 8, and 
     FIGS. 10, 11 and 12 are views similar to FIG. 8 illustrating further modifications. 
    
    
     In the example illustrated in FIGS. 1 to 3 a panel is formed from a plurality of fabricated rigid sheets 1 of which two adjacent similar sheets are illustrated. The sheets 1 are profiled for engagement with adjacent similar sheets and whilst they can be formed in any suitable material of sufficient rigidity in the profiled condition they are preferably made of metal such as aluminum or steel or their alloys. In this example, the sheets are roll-formed of an aluminum alloy identified as NS3-H4 and are 1 mm. thick. 
     Each sheet 1 is formed with a first rearwardly extending flange 2 along one longitudinal edge 3 which is the upper edge as seen in FIG. 1 and a second rearwardly extending flange 4 along the lower opposed longitudinal edge 5. The upper flange 2 is connected to the associated longitudinal edge by a first fold 6 and the lower flange 4 is connected to the lower longitudinal edge by a second fold, both folds being of substantially U-shape and being dimensioned so that the first fold 6 is engageable within the second fold 7 when the flanges 2 and 4 of adjacent similar sheets are in supporting engagement. Both folds 6 and 7 are disposed rearwardly of the general plane of the sheet and open in the same direction, the fold 6 being connected to the upper longitudinal edge 3 by a continuation 2a of the flange 2 to provide a supporting ledge for the next adjacent sheet, the fold 7 being connected to the lower longitudinal edge 5 by a similar continuation 4a of the flange 4. The flange 3 extends rearwardly of the general plane of the sheet 1 by a distance less than does the flange 4 and is formed with a downwardly depending flange 8 which is of lesser width than a corresponding downwardly depending flange 9 formed on the flange 4. The flange 9 has an inturned lip 10 of a width sufficient to engage under the free edge of the flange 8 of an adjacent similar sheet. 
     Securing means is provided by displacing a sector shaped piece of metal rearwardly of the rear walls of the folds 6 and 7, this being done at regular intervals to provide projections 11 which leave sector shaped apertures 12 which are in register when adjacent sheets are assembled. As seen in FIG. 1 the first fold 6 extends above and beyond the longitudinal edge 3 whereas the second fold 7 extends behind the sheet. In assembling a plurality of sheets 1 to form a panel, the closed end of the fold 6 of one sheet is presented to the open end of the fold 7 of the adjacent sheet. As the depth of the fold 6 is advantageously slightly less, e.g., 1 mm., than the width of the flange 9, the lip 10 of the upper sheet will abut against the flange 2 of the lower sheet. The inherent resilience of the sheet material is sufficient to enable the flange 9 to be bowed outwardly to enable the free edge of the lip 10 to clear the rear edge of the flange 2 and enable the fold 6 to be engaged within the fold 7 to an extent sufficient to bring the flanges 2 and 4 and the continuations 2a and 4a into supporting engagement. To facilitate the outward bowing of the flange 4, the continuation 4a is preferably curved or radiused as shown. When the flanges 2 and 4 are in supporting engagement, the lip 10 extends underneath the free edge of the flange 8 of the adjacent sheet. 
     When inserting the fold 6 into the fold 7 with the projections 11 and apertures 12 in register the projections 11 in the rear wall of the fold 6 tend to be displaced inwardly by the rear wall of the fold 7 until they reach an aperture 12 in the latter when they return to their normal position and engage in an aperture 12 in the fold 7. 
     When assembled, it can be seen that displacement of a fold 6 out of a fold 7 in an adjacent sheet is opposed by the lip 10 and by the weight of the sheets. Relative longitudinal sliding movement of adjacent sheets 1 is opposed by engagement of the projections 11 in the fold 6 with the apertures 12 in the fold 7 of the adjacent sheet. Relative angular displacement of adjacent sheets is prevented by engagement of the walls of the folds 6 and 7, the flanges 2 and 4, the continuations 2a and 4a and the lip 10. 
     Thus the sheets 1 enable a panel of relatively large area to be readily assembled from individual sheets and to a significant degree of rigidity. This is of particular importance in the construction of van bodies and containers for freight and for walls of buildings. 
     The sheets 1, as illustrated, are conveniently formed with corrugations and may be roll-formed to any desired length. It may be convenient, in assembling the sheets to assemble them in staggered relationship. 
     It will be appreciated that, in the arrangement shown, the projections 11 in the folds 6 of adjacent sheets may be deformed inwardly to displace them from the aperture 12 in which they are engaged, e.g., by a hammer blow, thereby making it possible for a sheet in a panel assembly to be removed by sliding it longitudinally relative to adjacent sheets. 
     The example illustrated in FIGS. 4, 5 and 6 is similar to that described with reference to FIGS. 1 to 3 and like reference numerals are used to denote like parts. In this example, the rear wall of the fold 6 and the rear wall of the fold 7 are formed with spaced apertures 22 of substantially rectangular shape the projections 11 of the previous example being omitted. The projections are formed on a separate strip 23 as projections 21, the strip 23 being dimensioned to be received in the fold 6. As can be seen from FIG. 6, the securing means in this example is provided by the strip 23 formed with apertures 24 at a spacing corresponding to that of the spaced apertures 22. These apertures 24 are substantially of I-shape to leave two wings 24a which when bent out of the general plane of the strip 23 along fold-lines 24b provide the projections 21 which are of trapesium shape, the upper free edge being slightly longer than twice the thickness of the metal sheet 1 and less than the lower free edge and the outer free edge 21a being inclined to provide a camming action. 
     In assembling two sheets according to this example, the fold 6 is inserted into the fold 7 of the adjacent similar sheet as before and it is preferred to provide a sealing cord 25 in the base of the fold 7. With the apertures 22 in the folds 6 and 7 in register, the strip 23 is inserted into the fold 6, the projections 21 effecting a camming action until they engage in the registering apertures 22 in the folds 6 and 7. As an alternative, the strip 23 may be inserted into the fold 6 before the fold 6 is inserted into the fold 7 of the adjacent sheet. 
     As will be seen at 23a, it is preferred that the lower edge of the strip 23 be thickened slightly as compared with the general thickness of the strip. 
     In the modified sheet illustrated in FIG. 7 the folds 6 and 7 of the previous examples are enlarged so that their bases or closed ends occupy the whole width of the flanges 2 and 4 of the previous examples. These enlarged folds are identified in FIG. 7 as 26 and 27 and their bases as 28 and 29. These bases 28 and 29 are deformed at spaced intervals along their length to provide slots 30 and 31 with depending walls 32 and 33 which register and engage with each other when adjacent panels are assembled. These slots 30 and 31 with their depending walls 32 and 33 can be regarded as interrupted subfolds in the main folds 26 and 27. 
     In the modification illustrated in FIGS. 8 and 9 the folds 26 and 27 are omitted, the flanges 2 and 4 of the examples illustrated in FIGS. 1 to 6 being retained with the interrupted sub-folds of the example illustrated in FIG. 7 being retained. 
     FIG. 10 illustrates a modification of the arrangement illustrated in FIGS. 8 and 9. In this case, the sub-folds are provided by slots 30 and 31 but the opposed longitudinal side-walls 32 and 33 of these slots are omitted but the base of the slots is retained as at 34 and 35. It will be appreciated that in the examples illustrated in FIGS. 8, 9 and 10, the walls 32 and 33 of the slots or the bases 34 and 35 of the slots are obtained by deformation out of the flanges 4 and 2. 
     The modification illustrated in FIG. 11 is similar to the embodiments described with reference to FIGS. 1 to 6 in that the folds 6 and 7 are retained. In this case the fold 6 has a greater depth than the fold 7 but is cut away at intervals along its length as at 46a to leave projections 46b which extend through apertures 47a provided by cutting the fold 7 away at corresponding intervals. 
     The modification illustrated in FIG. 12 is similar in many respects to that described with reference to FIG. 11 but in this case the fold 6 is inverted as shown at 56 and is substantially the same dimension as the fold 7 which is cut away as in the previous example to provide spaced apertures 47a. The folds 56 and 7 face each other and locate a keying strip 56a formed at intervals with projections 56b which extend through the apertures 47a. 
     It will be appreciated that a sheet according to the present invention can be economically manufactured and can readily be assembled to provide rigid panels of large area and that, if necessary, individual sheets in an assembled panel can be replaced.