WO1992018726A1

WO1992018726A1 - Panel system

Info

Publication number: WO1992018726A1
Application number: PCT/GB1992/000654
Authority: WO
Inventors: Richard Berge
Original assignee: Richard Berge
Priority date: 1991-04-11
Filing date: 1992-04-10
Publication date: 1992-10-29
Also published as: DE69211988D1; AU1589692A; EP0579691B1; AU658879B2; DE69211988T2; CA2108171A1; ES2090627T3; GB9107684D0; ATE140054T1; EP0579691A1

Abstract

A panel system (10) has panels (12) disposed side by side and connected together by connecting elements (14). The elements (12, 14) are constructed from cardboard or plastics sheets. The connecting elements may have line slots (36, 38) or centre apertures (37) which form slots when the connecting element is folded and which grip folded back edges (50, 52) of adjacent panel elements, while dovetail slots (22, 24) in the panel edges retain the connecting elements in position, once the latter have been partially unfolded after insertion.

Description

PA EL SYSTEM

5 This invention relates to a panel system and particularly to non-permanent panel systems used at exhibitions and conferences or for use as scenery in television studios and theatres or at point-of-sale locations to provide a surface to create a scene or as a surface on which to 10 display pictures or graphics.

In exhibitions and conferences as well as in the theatre and television there is extensive use of temporary structures to provide areas in which to display products

15 or to provide surfaces which are decorated to produce scenery. There exists an extensive market for panel systems, but these are generally constructed from various strong materials such as timber, plastics and aluminium extrusions.

20

Whilst there is little wrong with existing products and methods, the cost of providing such structures on sale or hire is relatively high. The systems currently available f tend to be bulky and heavy which means that transport-

*. 25 ation and erection can be expensive. It is an object of the present invention to provide a panel system which is easy to make, easy to assemble, lightweight and reasonably inexpensive.

The present invention provides a panel structure comprising panels of substantially rectangular sheets of cardboard or like material folded at least twice along fold axes adjacent to opposite edges thereof and joined to adjacent similarly constructed sheets by connecting elements adapted to fit into dovetail slots cut into said edges of each panel.

In a typical installation several of said panels are connected to form a continuous wall and said connecting element extends through the dovetail slots of said several panels.

Preferably more than one of said dovetail slots is provided on each edge, vertically spaced from one another so that more than one connecting element may be employed to improve the strength of the panel structure.

In one preferred embodiment, it is the narrow dimension of the dovetail slot which opens at the edge of the panel, said connecting element being a first form thereof and comprising a sheet of said cardboard or like material folded along a longitudinal fold line, and said element having line slots cut into its edges on either side of said fold line, said line slots being of a width approximately the same as two thicknesses of said panel, the first connecting element being adapted to be inserted through the opening of two adjacently disposed dovetail slots, to engage said line slots about the base of said dovetail slots so as to secure the edges of the panels together, and to be unfolded as far as said dovetail slots permit so as to retain said first connecting element in the dovetail slots.

Preferably, the depth of each line slot is such that the distance between the base of each line slot and the fold line is substantially the same as the depth of each dovetail slot. Preferably the dovetail slots and said line slots, and said fold axes and the width of said first connecting element, are all arranged such that said line slot is substantially the same length as the distance from the base of the dovetail slot, in the direction of its diverging edges, to said fold axes.

This ensures that when the first connecting element is in position, the geometry of the arrangement provides a secure location of the joining parts.

Alternatively, however, it may be the wide dimension of the dovetail slot which opens at the edge of the panel and said connecting element is therefore in its second foπn in which it comprises a sheet of said cardboard or like material folded along a longitudinal fold line, said second element having line slots cut into its edges on either side of said fold line of a width approximately the same as two thicknesses of said panel, and a centre aperture positioned across said fold line, said centre aperture being of a width approximately the same as two thicknesses of said panel, the second connecting element being adapted to be inserted through the openings of an adjacent pair of said dovetail slots engaging said aperture about the base of the said dovetail slot so as to secure together the edges of said panel.

Preferably, the edges of the dovetail slot have, between its opening and its base, a return, and said connecting element is adapted to be partially unfolded after insertion thereof in said dovetail slots so as to engage the base of each line slot with said return. This secures the edges of said panel, and prevents it from further movement.

Preferably the extent of the centre aperture of said connecting element on either side of the fold line is substantially the same as the distance from the base of the dovetail slot of said panel to the fold axis of said panel. Preferably, said dovetail slot has a base of sufficient width to allow the connecting element to be partially unfolded and lie flat against the edges of the dovetail slot.

Preferably the centre aperture extends substantially perpendicularly to said fold line. Moreover, it may be essentially rectangular. The centre aperture of said second connecting element constitutes a slot when the element is folded along its fold line, and the opening of said slot may be chamfered to ease introduction of the connecting element over the bases of the dovetail slots in adjacently disposed panels.

The second form of said connecting element is preferred because it is stronger than the first form at the very point where there is maximum stress on it from adjacent panels attempting to separate by extraneous forces imposed on them. This point is that part of the connecting element closest, in an assembled wall structure, to the fold axes of adjoining wall panels; and in the case of said second connecting element, this is at the centre of the centre aperture at the longitudinal fold of the connecting element. In the case of the first form of connecting element, this point is at the separate ends of its line slots, which are not reinforced by a fold. Preferably there are at least four dovetail slots in each panel edge. These are preferably arranged in two pairs near the top and bottom of each panel. Moreover, there are preferably multiple line slots and centre apertures, as the case may be, spaced along said connecting element, each line slot being separated from the next by the separation of said fold axes in said panels, or by convenient fractions of said separation.

Thus, when several panels are connected together by a plurality of connecting elements, each connecting element joins at least four panels together, the disposition of said connecting elements in each pair of dovetail slots can be staggered with respect to one another so that each joint between adjacent panels is stabilised by a connecting element also joining panels on either side of said adjacent panels.

Preferably each connecting element joins six panels,

Needless to say, connecting elements may be shortened where the panel system ends or is formed into a corner. The ends of a run of panel elements may be finished by special end panels. An internal corner between adjoining wall systems does not pose any difficulty. Whereas each panel is folded back at right angles along said fold axes where a flat wall system is required, at a corner one edge of one panel will not be folded back at right angles but at some greater angle. Where a perpendicular joint between panel systems is required, the edge will not be folded back at all, and may even be folded forwards when an acute internal angle is required between adjoining sets of panels.

Said special end panels may comprise dovetail slots along one edge, said dovetails opening at said edge at their wide dimension, and dovetail cuts in the other edge, said dovetail cuts opening at their narrow dimension and being adapted to engage the back of a connecting element received in the dovetail slots.

Preferably, said special end panels further comprise four folds between said edges and parallel therewith to form square corners when said dovetail slots engage a connecting element and said dovetail cuts engage the back of said element. Each fold may be separated by a dimension equal to the overall thickness of a panel when a connecting element is inserted in its dovetail slots. It will be apparent that a wide variety of panel structures are achievable by the present invention which is nevertheless very inexpensive to manufacture.

For example, two walls can be disposed back to back if a modified connecting element is employed and when it is the wide dimension of the dovetail slots which open at the edges of the panels. Here the modified connecting element comprises merely two of said second form of connecting elements joined edge to edge, and which is folded into a diamond section configuration. Thus half the modified connecting element connects one side of the double wall, while the other half of the element connects the other side of the wall.

A further refinement of the present invention is the construction of curved walls, of single ply, using further modified connecting elements. In the case of wall panels in which the dovetail slots open at the edge of the panel in their narrow dimension, the connecting element line slots which are separated from one another along the length of the connecting element by an amount equal to the separation of said fold axes are inclined with respect to each other. In the case of wall panels in which the dovetail slots open at the edge of the panel in their wide dimension, the connecting element centre apertures which are separated from one another along the length of the connecting element by an amount equal to the separation of said fold axes are inclined with respect to each other. In both cases, the effect of the inclination of the line slots or centre apertures (as the case may be) is that when two connecting elements are used to connect two adjacent wall panels, one connecting element being locked in the dovetail slots of two edges of one panel and an adjacent edge of the other panel, and the other connecting element being locked in the dovetail slots of two edges of said other panel and the adjacent edge of said one panel, in both cases employing the inclined line slots or centre apertures (as the case may be) to effect said locking, then the two wall panels are connected at an angle with respect to each other, rather than in line. If the same process is employed with multiple panels, then a close approximation to a curved surface can be achieved, particularly if the separation of said fold axes is kept to a minimum.

An appropriate material for both the panels and connecting elements is three ply cardboard having a quality finish to one face. For most purposes the cardboard will require a flame retardent finish in order to meet regulations. Various other materials including plastic laminates could also be employed. Thus a panel structure according to the present invention is very simple and consequently light and inexpensive. It has the necessary ridigity for most temporary purposes and if constructed from substantial material could be used for more permanent structures. If constructed from cardboard, a structure according to the present invention can be modified or profiled using a sharp knife or fine saw.

The invention is further described hereinafter, by way of example only, with reference to the accompanying drawings, in which:-

Figure 1 is a perspective rear view of a panel structure according to a first embodiment of the present invention?

Figure 2 is a perspective front view of a structure as shown in Figure 1;

Figure 3 is a plan view of a blank for a panel element forming part of the panel structure of Figure 1;

Figure 4 is a plan view of a blank for a first form of a connecting element forming part of the panel structure of

Figure 1;

Figure 5 is a top plan view of part of a panel structure as shown in Figure l; Figure 6 is a section on the line A-A of Figure 5;

Figure 7 is a perspective rear view of a second preferred embodiment of a panel structure according to the present invention; Figure 8 is a plan view of a blank for a panel for the structure of, Figure 7;

Figure 9 is a plan view of a blank for a connecting element in its second form for the structure of Figure

7; Figure 10 is a top plan view of part of a panel structure as shown in Figure 7;

Figure 11 is a section on the line B-B of Figure 10;

Figure 12 is a rear view of a multi-panel structure according to the present invention; Figure 13 is a top view of a typical corner joint;

Figure 14 is a plan view of a gusset for an internal corner of a wall structure according to the present invention;

Figure 15 is a rear perspective view of an internal corner joint using the gusset of Figure 14;

Figure 16 is a plan view of a gusset for an external corner of a wall structure according to the present invention;

Figure 17 is a rear perspective view of an external corner joint using the gusset of Figure 16; Figure 18 is a perspective view of a double wall employing the second embodiment of the present invention;

Figure 19 shows an alternative arrangement of the wall structure of Figure 18;

Figures 20a and b are plan views of blanks for special end panels;

Figure 21 is a plan view of a wall structure using the special end panel of Figure 20; Figure 22 is a sectional view, similar to Figures 6 and

11, of the wall structure of Figure 18;

Figure 23 is a plan view of a blank for a curve forming connecting element, in its second form; and.

Figure 24 shows a curved wall structure achieved using the connecting element of Figure 23.

In the drawings, a wall structure 10 comprises a series of wall panels 12 joined by connecting elements 14. Each element 12,14 is constructed from a sheet of three ply cardboard or like material, preferably with a quality finish on one face, and rendered fire retardent by appropriate treatment. Alternatively appropriate plastics laminates may be employed.

Each panel and connecting element is cut to blanks as shown in Figs. 3 and 4 respectively. Each panel 12 is provided with fold lines or axes 16 adjacent each long edge 18,20 to form sides 50,52 respectively. Four dovetail slots 22,24, a,b,c,d are cut in the edges 18,20 at corresponding positions in two pairs a,b and c,d adjacent to each end of the panel.

Each connecting element 14 is provided with a central longditudinal fold line 30. Each long edge 32,34 is provided with line slots 36,38 a,b,c,d separated by a distance corresponding to the separation between the fold axes 16 on the panel 12.

With reference also to Figure 6, the distance x between the base of each line slot 36,38 and the central fold line 30, is arranged to be approximately the same as the depth y of the dovetail slots 22,24. Moreover, the depth w of the line slots 36,38 is arranged to be approximately the same as the radial distance z from the base of the dovetail slots 22,24, in the direction of their side edges, to the adjacent fold axes 16.

The width r of the line slots 36,38 is arranged to be approximately the same as two thicknesses of the panels 12. Also, the width s of the opening to each dovetail slot 22,24 is arranged to be larger than two thicknesses of the connecting element 14 (equivalent to the separation t of the fold line 30, which is arranged as a pair of folds) . This is achieved by parallel cuts 33 at the opening of each dovetail slot.

The purpose of these dimensions is explained in the following description although it should be understood that these dimensions are merely preferable and are not absolutely essential for the satisfactory operation of a panel structure according to the invention.

To assemble a panel structure 10 as shown in Figures l and 2 four panel elements are first folded along the fold axes 16 so that sides 50, 52 thereof are substantially at right angles to face 54.

The edge 18 of one panel 12 is then aligned with the edge 20 of the next panel so that the dovetail slots 22, a,b,c,d and 24 a,b,c,d of adjacent panels are aligned with one another.

A connecting element 14 is then folded flat along its longitudinal fold line pair 30 and inserted into the mouths 33 formed by adjacent dovetail slot pairs 22,24a (fold line 30 entering last) . Further connecting elements may be inserted in dovetail slot pairs 22,24, b,c, and d. Each connecting element 14 is inserted so that each line slot 36, now paired with adjacent line slots 38, are engaged with the base of each dovetail slot pair until the edges 32,34 abut the back face 54 of each panel 12. The mouths 35 of the line slots 36,38 may be chamfered to ease insertion. The connecting element 14 may then be opened within the confines of the dovetail while being coaxed further into engagement against the end face 54, and until the position shown in the drawings is achieved. To ease opening of the connecting element, thumb slots 43 are cut in its edges. With the dimensions given as above, this results in the fold lines 30 lying flush with the edges 18,20 of the panels.

As shown in Figures 5 and 6 each connecting element 14 is retained in position by the dovetail slots 22,24 and, for most practical purposes, the connecting elements are held firmly in place. This is further aided by notches 39 in each corner of the dovetail slots which catch and locate the base of each line slot when the connecting elements are opened. More importantly however, each panel 12 is now locked to the next by the line slots 36,38 in each connecting element gripping adjoining sides 50,52 of adjacent panels, hence the relative dimension r and the thicknesses of two panels. The result is a panel structure 10 which has a satis¬ factory frontal appearance and which can be extended by as many panels 12 as required.

A preferred alternative embodiment of the present invention is shown in Figures 7 to 11. This has a similar structure and assembly technique to the first embodiment described above. Consequently like parts are given the same reference numeral, except with an apostrophe where they differ from the first embodiment.

For reasons explained further below, the dovetail slots 22•,24' have been reversed from their orientation in the first embodiment, so that their major dimension, rather than their narrow dimension, now forms their mouth 33* . Moreover, each dovetail slot is also provided with a return 41. A modified form of connecting element 14' is employed, which has line slots 36',38', as before, but also centre apertures 37 a to j.

With reference to Figures 9 and 11, the depth w* of each line slot 36',38' is arranged to be the same as the width z- of the return 41. Moreover, the depth p of the centre aperture on either side of the fold line 30', which in this case is merely a single fold, is arranged to be approximately the same as the distance q from the base 45 of the dovetail slot, in the direction of its tapering edges, to the adjacent fold axes 16. Indeed, the tapering edges, if they did not terminate at the base 45, are so arranged that they would otherwise meet at the fold axis 16.

In this embodiment, it is the centre apertures 37 which have the width r¹ arranged to be approximately the same as two thicknesses of the panels 12. The line slots 36',38' may likewise have a width r" which is the same as two thicknesses of panels, but this is not critical as will be apparent from the description below.

To assemble a panel structure 10' , four panels 12' are first folded along their fold axes 16. As before, the edge 18' of one panel is then aligned with the edge 20' of the next one. Next, a connecting element 14' is folded along its longditudinal fold line 30' and inserted into the mouths 33' of the dovetail slot pairs 22',24a (fold line 30' first). Further connecting elements are inserted in the remaining slot pairs 22,24, b,c, and d.

Each connecting element 14' is inserted so that each centre aperture 37, which by virtue of the folding of the element now forms a slot, is engaged over the base 45 of each dovetail slot pair 22,24. By allowing the connecting element 14 to partially unfold, the line slots 36',38' engage the return 41 so that the connecting ele ent 14' is locked in the dovetail slots 22',24'. The natural resilience of the material of the connecting elements springs them apart so that they keep engaged with the returns 41.

Thus, each panel element 12• is firmly locked to the next by both the centre apertures 37 and the line slots 36*,38'. Indeed, the connection is stonger than the first embodiment because the centre apertures 37, when they are folded in half, are much stronger than the line apertures 36,38 of the first embodiment. In that embodiment, the line slots 36 and 38 work independently of one another, while here, the centre aperture forms two slots which each support and reinforce the other.

Where more than four panel elements are used (with either embodiment) such as illustrated in Figure 12, further connecting elements 60, 62, 64, 66 are employed and these are disposed in staggered relation with respect to one another so that each panel 12 is joined to one on either side by at least two connecting elements. This ensures that the resulting panel structure has the necessary stability.

If desired, a modified panel 80 (see Figure 13) may be employed at strategic points and which has a central fold line 82. When the modified panel is used, the sides 50',52' of the panels are inserted into otherwise vacant line slots 36',38' (and centre apertures 37 in this case of the second embodiment shown in Figure 13) . It is for this purpose that the line slots and centre apertures are located at spacings equal to half the separation between the fold axes 16 on the panels 12, and not the full separation as shown in Figures 1 to 6. On the other hand, this spacing, and the modified panel 80, are equally applicable to the first embodiment. When these modified panel elements 80 are employed, the face of the panel element projects from the surface of the panel structure increasing the depth of the structure and thus its stability.

Figure 13 also illustrates a joint between two walls which is easily achieved by the joining method of the present invention and which further improves the stability of the panel structure.

Figures 14 to 17 show special corner units 112,112', reinforced by gussets 90,100. With reference first to Figures 14 and 15, the gusset 90 comprises a sheet of cardboard or like material having two support edges 92,93 at an angle A with respect to one another. In this case the angle A is a right angle. The support edges 92,93 are themselves supported by tab pairs 94,96 whose function is explained further below. At an angle B (which is always substantially a right angle) to the edges 92,93 are abutment edges 95,98, which are each provided with tongues 97. The tongues 97 have press-out tabs 99 formed in them.

A panel 12 is then folded centrally about its fold line 82; in Figure 15, this is internally at the angle A. The tab pairs 94,96 are then folded, one up, one down, on each of four gussets 90. These are offered up to the folded panel and the tongues 97 are pressed through apertures 23 provided for this purpose in each side 50,52 of the panels 12 (see also Figure 3). The length m of the slots 23 is slightly less than the width of the tongues 97 so that barbs 101 on the tongues engage the edges of the apertures 23 after being pushed through them. Moreover, after insertion of the tongues 97 in the apertures 23, the tabs 99 may be bent downwardly to further ensure that the tongues remain firmly engaged in the apertures 23.

The purpose of the tabs 94,96 can now be appreciated, since they bear against and support the rear surface of the panel 12, and so that the panel is constrained to the angle A, which is of course the angle between the support edges 92,93. It will be appreciated that a corner unit 112 so-formed can easily be connected to the end of a panel stucture 12a. This is achieved by pushing the tongues 97 through the corresponding apertures 23 of the adjoining panel 12a. For this purpose the separation d of the barbs 101 and the tabs 99 from the respective abutment edges 95,98 are arranged to be twice the thickness of the panels 12. In any event, the dovetail slots of the corner unit 112 and the adjoining panel 12a are of course aligned so that connecting elements (not shown) can further secure the two components together.

The arrangement of Figures 16 and 17 is essentially the same, except that here it is an external corner that is formed with the aid of the gussets 100.

Figures 18 and 19 show two possible arrangements employ¬ ing the second embodiment of the present invention. Referring also to Figure 22, a double-ply panel structure 10" is formed from two panels 12b and 12c arranged back- to-back. The two panel plys are secured together by a connecting element 14" which is in the form of two connecting elements 14'a,14'b joined edge to edge at 85. Needless to say, the parts 14 'a and 14'b of the element 14" also secure together the individual panels in each ply. The element 14" is, of course, a single component. It adopts a diamond configuration when in use. Figures 18 and 19 also show the use of special end panels 12d which enable wall ends and corners to be provided for this double ply structure. Figure 20b is a plan view of the blank for panel 12d, which has the same dimensions, and has the same dovetail slots 22*,24' and fold axes 16, as the panel 12' of Figure 8. However, it has extra fold lines 16' and 16". The former, when employed, allow the panel to be used as shown at 12d in Figures 18 and 19, while the latter allow the panel to be used as shown at 80 in Figure 18, or indeed as panel 80 in Figure 13.

Figures 20a and 21 illustrate a further special end panel 70, which is provided with one side 72 shaped in an identical fashion to sides 50' ,52' of the panel element 12' of Figure 8. Fold lines 74a,b, and c are positioned equidistant to each other at a distance equal to the width of side 72. Fold line 76 is ideally positioned at a distance from fold line 74c equal to the width of side 72 less the thickness of one panel. Dovetail cuts

78a,b,c,d are provided along the edge of side 80 spaced to correspond to the final positions of connecting elements 14' in a completed panel structure. The special end panel element 70 is attached to a panel structure 10' by means of its dovetail slots 22* on side 72. Right angle folds are made along fold lines 74a,b,c,d and side 80 is positioned adjacent to side 72. Dovetail cuts 78a,b,c,d are positioned over the exposed edges of connecting elements 14 ' which are temporarily sqeezed together to allow insertion into mouths 82 of each dovetail cut.

Finally, Figures 23 and 24 show a special connecting element 14", and a curved panel structure 10"' which is created when the element 14" is employed in single ply panel structures. The connecting element is used in exactly the same way, but it is provided with inclined centre apertures 37' at each end. When folded along centre fold line 30", the inclined apertures 37' become inclined slots. In Figure 23, they are inclined inwardly, and form inwardly directed wall joints as shown in Figure 24. Outwardly inclined slots would form convex wall structures. The connecting element 14" is long enough to join only one panel 12' to a single neighbour on either side. To form curves, each neighbour must likewise be connected to their neighbours by the special connecting elements 14".

Claims

1. A panel structure (10,10'), characterised in that it comprises panels (12,12') of substantially rectangular sheets of cardboard or like material folded at least twice along fold axes (16) adjacent to opposite edges (18,18*,20,20') thereof and joined to adjacent similarly constructed sheets by connecting elements (14,14') adapted to fit into dovetail slots (22,22'24,24') cut into said edges of each panel.

2. A panel structure as claimed in claim 1 characterised in that several of said panel elements are joined together to form a continuous panel structure and said connecting element extends through the dovetail slots of said several panels.

3. A panel structure as claimed in claim 1 or 2 characterised in that more than one of said dovetail slots is provided on each edge, vertically spaced from one another so that more than one connecting element may be employed to join two adjacent panel elements.

4. A panel structure as claimed in any preceding claim, characterised in that it is the narrow dimension (33) of the dovetail slot (22,24) which opens at the edge of the panel (12) , said connecting element being a first form (14) thereof and comprising a sheet of said cardboard or like material folded along a longitudinal fold line (30) , and said element having line slots (36,38) cut into its edges (32,34) on either side of said fold line, said line slots being of a width (r) approximately the same as two thicknesses of said panel, the first connecting element being adapted to be inserted through the openings (33) of two adjacently disposed dovetail slots, to engage said line slots about the base of said dovetail slots so as to secure the edges of the panels together, and to be unfolded as far as said dovetail slots permit so as to retain said first connecting element in the dovetail slots.

5. A panel structure as claimed in claim 4, character¬ ised in that the depth (w) of each line slot is such that the distance (x) between the base of each line slot and the fold line (30) is substantially the same as the depth (y) of each dovetail slot.

6. A panel structure as claimed in claim 5, character¬ ised in that the dovetail slots and said line slots, and said fold axes and the width of said first connecting element, are all arranged such that said line slot is substantially the same length (w) as the distance (z) from the base of the dovetail slot, in the direction of its diverging edges, to said fold axes.

7. A panel structure as claimed in any of claims 1 to 3, characterised in that it is the wide dimension (33*) of the dovetail slot (22',24') which opens at the edge of the panel (12') and said connecting element (14*) is in its second form, in which it comprises a sheet of said cardboard or like material folded along a longitudinal fold line (30'), said second element having centre apertures (37) positioned across said fold line, said centre apertures being of a width (r') approximately the same as two thicknesses of said panel, the second connecting element being adapted to be inserted through the openings (33*) of an adjacent pair of said dovetail slots engaging said aperture about the base of the said dovetail slot so as to secure together the edges of said panel element.

8. A panel structure as claimed in claim 1 , character¬ ised in that line slots (36*,38') are cut into the edges of the second connecting element on either side of said fold line and the edges of each dovetail slot have, between its opening and its base, a return (41) , and said connecting element is adapted to be partially unfolded after insertion thereof in said dovetail slots so as to engage the base of each line slot with said return.

9. A panel structure as claimed in claim 7 or 8, characterised in that the extent (p) of the centre apertures on either side of the fold line is substant- ially the same as the distance (q) from the base of the dovetail slot of said panel to the fold axis (16) of said panel.

10. A panel structure as claimed in any of claims 7 to 9, characterised in that said dovetail slot has a base of sufficient width to allow the connecting element to be partially unfolded and lie flat against the edges of the dovetail slot.

11. A panel structure as claimed in any of claims 7 to 10, characterised in that the centre aperture extends substantially perpendicularly to said fold line and is essentially rectangular.

12. A panel structure as claimed in any of claims 2 to 10, characterised in that there are four dovetail slots in each panel element edge, arranged in two pairs near the top and bottom of each panel element.

13. A panel structure as claimed in any preceding claim characterised in that a connecting element joins six panel elements.

14. A panel structure as claimed in claim 7 or in any of claims 8 to 13 when dependent on claim 6, characterised in that special end panels (70) comprise dovetail slots along one edge and dovetail cuts (78) in the other edge, said dovetail cuts opening at said other edge at their narrow dimension and being adapted to engage the back of a connecting element received in the dovetail slots.

15. A panel structure as claimed in claim 14, character¬ ised in that said special end panels further comprise four folds (74a,b,c,76) between said edges and parallel therewith to form square corners when said dovetail slots engage a connecting element and said dovetail cuts engage the back of said element.

16. A panel structure as claimed in claim 15, character¬ ised in that each fold is separated by a dimension substantially equal to the overall thickness of a panel structure (10) when a connecting element is inserted in its dovetail slots.

17. A panel structure as claimed in claim 7 or any of claims 8 to 16 when dependent on claim 7, characterised in that two panels (12b,12c) are disposed back to back and a modified connecting element (14") is employed, which modified connecting element comprises two of said second form of connecting elements (14'a,14'b) joined edge to edge, and which is folded into a diamond section configuration.

18. A panel structure as claimed in claim 4, 5 or 6, or in claims 12 or 13 when dependent on claim 4, character¬ ised in that the connecting element line slots which are separated from one another along the length of the connecting element by an amount equal to the separation of said fold axes, are inclined with respect to each other.

19. A panel structure as claimed in claim 7 or any of claims 8 to 17 when dependent on claim 7, characterised in that the connecting element centre apertures which are separated from one another along the length of the connecting element by an amount equal to the separation of said fold axes are inclined with respect to each other.

20. A panel structure as claimed in claim 18 or 19, characterised in that two connecting elements are used to connect two adjacent wall panels, one connecting element being locked in the dovetail slots of two edges of one panel and an adjacent edge of the other panel, and the other connecting element being locked in the dovetail slots of two edges of said other panel and the adjacent edge of said one panel, in both cases employing the inclined line slots or centre apertures, as the case may be, to effect said locking, the two wall panels being thereby connected at an angle with respect to each other.