WO2001036125A1

WO2001036125A1 - Structural components and their manufacture

Info

Publication number: WO2001036125A1
Application number: PCT/GB2000/004353
Authority: WO
Inventors: Jonathan Leslie Evans
Original assignee: Jonathan Leslie Evans
Priority date: 1999-11-17
Filing date: 2000-11-16
Publication date: 2001-05-25
Also published as: AU1402701A; JP2003514159A; CA2360434A1; EP1144140A1; ZA200105697B; CN1343150A; GB9927019D0

Abstract

A continuous, cold rolled metal section for forming an n-sided closed frame is divided along its length by transverse aligned cuts (1, 2, 3) in longitudinally spaced pairs at its opposite sides respectively, the cuts dividing the section into the number of sides (6, 7, 8, 9) of the frame which are foldable relative to one another to form a predetermined angle of the frame, in use. The two end sides (6, 9) of the section have in their respective sides, which overlap on assembly of the frame, holes (4, 5) respectively which, when said two end sides are at the correct angle to one another in the assembled frame, are spaced linearly apart by a predetermined distance. In this way the required frame geometry can easily be achieved, assembly requiring only a simple reference tool (11; 13).

Description

STRUCTURAL COMPONENTS AND THEIR MANUFACTURE

This invention relates to the processing of strip material and its subsequent assembly into structures/frames and panels. The invention also relates to the assembly of such panels and structural frames into three-dimensional modules for the commercial and residential building industries.

Steel is a building material that has a number of advantages over conventional materials such as bricks, concrete cement and timber. These advantages include: non-combustible; fully recyclable; very low waste during construction; dimensionally very accurate; very low maintenance; very high thermal and acoustic performance. The application of steel has been limited in that suppliers have not developed manufacturing techniαues which sufficiently exploit these potential advantages at a competitive price. Steel is presently a rather expensive alternative in most situations, particularly the housing industry, and is mainly found in niche applications where its many advantages outweigh the initial high costs.

One of steel's major potential advantages is the reduction in lead-time in the construction of a building as much of the pre-assembly work can be done off site. Typically, the degree of pre-assembly will vary on the application. This can range from the supply of internal (non-load bearing) partitions, through to load bearing panels which are connected together on site and structural modules. Such modules can be fully fitted out with all necessary decorations and interior fittings if required and located as a finished unit. Such panels and modules are typically fabricated from a plurality of cold- formed sections which are cut to length and then joined together (e.g. butt- welding). To ensure that the panels are square and dimensionally accurate, they are usually assembled on a jig that locates each section prior to fixing. For three-dimensional modules such jigs are large and complex.

One of the major limitations of such steel framing systems results from the variability in the design. This leads to high cost of design and expensive investment in jigs that are tailored to each new design. These overheads prohibit the use of steel in a number of applications and seriously limit its potential market.

There is therefore great advantage to be gained from a production method that can dramatically reduce the amount of assembly hardware required.

A flexible production method is described here that allows the manufacture of such panels and modules without the use of any complex jigs or locating tools. The only tools that are required are not specific to any particular panel design, thus drastically reducing the investment required in tooling for a design and eliminating the lead time associated with its manufacture. Furthermore, it is shown how such panels can be interconnected without jigs and how complete three-dimensional structures can be assembled with a high degree of inherent strength.

The key to the simplification lies in the ability of modern section rolling equipment to punch holes and cut to length sections with tremendous accuracy and repeatability. Thus it is possible to incorporate in the sections themselves, certain geometric information that can be used during the assembly process. Such information can take the form of such features as the overall length of a section, the location of a punched hole or the location of a notch for an intended fold.

In the preferred embodiment, it is possible to produce a section that needs no further processing to allow the formation of a panel of predetermined geometry with only one angular or linear dimension check. (In practice, the number of external references required equals N minus three, where N is the number of sides of the polygon that the frame describes. Hence, for a typical rectangular frame as found in the construction industry, only one reference dimension is required.)

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

Figure 1 is a perspective schematic view of a typical rectangular frame, the production of which the present invention, in one embodiment, seeks to simplify,

Figure 2 is a perspective view of a cold-formed metal section of the invention,

Figure 3 shows the section of Figure 3 being assembled into the form of the frame of Figure 1 , Figure 4 is a scrap view of a corner of the frame, together with a reference tool for checking the angle of the corner,

Figure 5 is a view similar to Figure 4, showing a different reference tool,

Figure 6 is a scrap view of a section of another embodiment of the invention,

Figure 7 is a scrap perspective view of the section of Figure 6 folded to form a frame,

Figure 8 is a scrap view of a section of a still further embodiment of the invention,

Figure 9 is a perspective view showing a length of the section of Figure 8 in the form of a lipped channel,

Figure 10 is a scrap perspective view of the channel section of Figure 9 folded to form a frame,

Figure 11 is a scrap view of a section of a yet still further embodiment of the invention,

Figure 12 is a scrap perspective view of the section of Figure 11 folded to form a frame,

Figures 13 and 14 correspond to Figures 9 and 10 for another embodiment of the invention, Figure 15 shows frames of the invention joined together to form a larger composite frame,

Figures 16a and 16b are respective scrap perspective views showing the means of joining together said frames,

Figure 17 is a perspective view of a modular frame for a building constructed with frames assembled from sections of the invention,

Figure 18 is an alternative building frame similar to that of Figure 17,

Figures 19 and 20 are respectively perspective views of different forms of triangular trusses assembled from sections of the invention,

Figures 21 and 22 are respectively perspective views of different shapes of further frames assembled from sections of the invention, and

Figures 23 and 24 are respectively perspective views of a section of the invention formed into a core, and a beam formed of said core between outer sections.

Conventionally, the closed rectangular frame A, shown in Figure 1, would be constructed using four separate pieces of section that are cut to length individually. Each section is then inserted into a jig which is adapted to the particular design of panel to be produced. When located, the sections are clamped in place so that the ends of the sections can be joined together (welded, riveted etc.) The role of the jig is to ensure that: 1) the individual sections locate relative to each other to form the correct effective dimensions of the frame, and 2) the sections meet at the correct angles.

It is recognised that if the individual sections of precise length can be accurately positioned relative to each other to form a closed pivoting rectangular frame, then only one angle needs to be specified in order to form a frame of the correct geometry. This invention describes a method of forming such a frame in this manner, thus greatly simplifying the framing process. This is made possible by the ability of modern section rolling equipment to punch and cut with tremendous accuracy during the rolling process. Therefore during rolling the section, it is possible to embed all the necessary geometric information required to form a frame in the manner presented.

There are two basic forms of this geometric information. Firstly, it is necessary to precisely locate consecutive sections relative to each other such that the linear dimensions of the frame are correct. To bring the ends of two plain sections together is not precise or robust enough to make frames of the accuracy required.

Two methods of locating adjacent sections are presented. The first method involves notching the section such that consecutive sections are joined by a tab that acts as a hinge corresponding to the apex of the frame. This method has the advantage that four consecutive segments can be quickly folded into a parallelogram of known perimeter (thus just needing the right angle at the open end to be defined to form a rectangular frame). One disadvantage of this method is that a large frame results in difficult handling of sections of length equal to the perimeter of the frame. A second disadvantage is that if the notch gap is wide, the pivot (and therefore the frame) is imprecise. A third disadvantage is that to close the frame, the open end still needs some means of locating accurately.

A second method involves punching precise holes near the ends of the separate, individual sections, such that they overlap when positioned correctly. This has the advantage that individual sections can be used, that are easy to handle even for large panels. The disadvantage is that some method of pinning through the holes at each corner must be employed to allow the parallelogram to go to the next stage of securing one angle.

A precise angle can be formed in two manners. Firstly an angular template or jig can be used. Secondly if reference points are formed at a known distance from the corner, then setting the diagonal distance between these reference points determines the angle by Pythagoras' theorem. The disadvantage of a template or jig is that a large tool would be required to form an accurate angle. The advantage of using a Pythagoras triangulation is that reference points can take the form of very accurate holes punched in the section during rolling. The correct angle can then be achieved by moving the frame (which will pivot either about the tabs or pinned holes) until a linear tool of known dimensions fits into the holes. Any error in the dimension of the reference tool will become an error in the apex angle. This error will be inversely proportional to the proximity of the reference holes to the apex. The first method of locating adjacent sections is demonstrated in Figure 2 where a single continuous cold rolled section, preferably of metal, has a length equal to the perimeter of the intended frame (with perhaps some minor adjustments for stretching during subsequent bending). This section has provision for three bends to be made in it, by means of pairs of notches 1, 2, and 3 in opposite sides of the channel section and extending into the base. At least two reference positions, in the form of holes 4, 5, are formed in the sides of separate segments 6, 7, 8, 9, here in end segments 6 and 9, rather than in two adjacent segments. With modern section rolling equipment, these notches and reference holes can be located with great accuracy. Consequently, to achieve the required geometry it will be sufficient to bend the section as shown in Figure 3, such that the two reference points are a certain absolute distance 10 apart. This can be ensured with the simplest of reference tools 11 as shown in Figure 4, having spaced pegs 12 at a predetermined distance apart to fit in holes 4, 5 when the segments 6 and 9 are at 90°. An alternative reference tool 13 could comprise both angular and linear information such as shown in Figure 5, for a right-angled corner of the frame. Of course for other angles set by tools 11 or 13 the distance 10 is not a hypotenuse of the triangle defined by the tool and the two frame sides, but merely the third side.

The location of the reference holes 4, 5 in the section could be a function of the frame perimeter such that regardless of the design, the final distance 10 between the holes would be a constant. This would allow the use of the same linear reference tool 11 on all panel designs, thus further reducing the lead times for a new design. Whilst the reference positions, such as holes 4 and 5, are preferably produced during the (cold) rolling process which forms a strip into the section or segment (side), this is not essential, and could be effected in a secondary, later operation.

The design of the notch that locates the bends between the segments can be varied to accommodate a number of different joining techniques, section profiles and material thicknesses. The simplest design would involve a channel or U section with notches cut either side of the base as shown in Figure 2. The notch dimensions should be chosen carefully. If the notch is too wide then the location of the bend may be vague and accuracy will be lost. If the notch is too narrow the bend may be too tight resulting in the channel sides fouling and not allowing a full ninety degrees to be achieved. It would be possible to design more sophisticated notches. For example, the central portion of the notch could be narrow to allow a tight accurate bend, whilst the notch 14a in the area of a side (Figure 6) could be angled to allow a mitred joint 14b as shown in Figure 7. This would mean that the joint surface would be flush providing a good mounting for any subsequent board application. However, most joining techniques require a degree of overlap of the segments which means that the design of the notch may need to take account of the section that the material will be formed into. For a simple channel section, little provision needs to be made to allow the fold to take place. If however, the section is of 'C section with returns 15 (Figures 8 to 10) on the channel sides (which have greater load bearing capabilities), some provision needs to be made as shown in Figures 8 to 10 to allow the section to be bent without the returns fouling.

It is also possible to facilitate the accurate and easy bending of the section by punching fold lines or perforations along the intended fold. Care must be taken however, not to weaken the section so that handling of the component becomes difficult prior to forming into a frame.

To avoid the overlapping regions of the bent corners from distorting the application of boards to the panels, these regions 16 can be swaged so that they are flush as shown in Figures 11 and 12. This can be done either in line or as a separate pressing operation.

In the overlap areas of the section, it is possible to punch congruent holes 17 that overlap when the segments are bent to the correct angle (or the end segments link up correctly) as shown in Figures 13 and 14. Instead of two overlapping holes, two printed dots or a hole aligning with a printed dot could be used. Thus any suitable alignment means could be used. There are numerous alternative methods of securing the overlapping regions, and the choice will depend on the application, speed required, expense and whether assembled on site or in the factory. Possible joining techniques include, welding (e.g. butt welding mitred joints or spot welding overlapping areas), riveting and clinching. To ensure maximum accuracy, the head of the joining tool can be modified such that the join can only take place once one or more locating pins on the tool is located through the two overlapping holes thus further ensuring the accuracy of the individual joints. This tool assembly can be extended such that it incorporates the linear and furthermore, the angular references in its structure. Such an assembly, when used in conjunction with the joining procedure, would reduce the total registration and joining to a single operation. In an extreme case, the linearly spaced holes 4 and 5 of Figures 4 and 5 could be positioned so that the spacing is zero, thus providing the reference in the same form as in Figures 13 and 14. The reference tool is thus now, in effect, a single peg through the two aligned holes rather than two pegs. Moreover, for example with a rectangular frame, such as A, the reference positions, i.e. holes 4, 5, in two adjacent sections could be spaced fully away from their common notch, so that the distance 10 is a diagonal of the frame. The holes 4, 5 thus each coincide with different holes 17, and can thus replace them, serving both to locate the sections and form a precise angle.

As a general rule, the greater the distance 10 between the reference holes 4, 5 the greater the achievable accuracy. If this distance 10 is reduced to zero, i.e. the holes overlap as in Figures 13 and 14, it is still possible to achieve the desired geometry without any reference tools. However, the disadvantage of dispensing with the measuring reference completely is the potential loss of accuracy as a small inaccuracy in the overlap can result in a disproportionately large error in the desired angle when compared to an equal error in a larger reference distance. It may thus be preferred to employ linearly spaced holes 4 and 5 as well as aligned holes 17, in the assembly of the frame.

Using the combination of an autolocating joining technique and a secondary angular or linear reference, it is possible to use this framing concept with totally independent sections rather than a continuous folding strip. This may be useful should the application demand different types of section to be formed into frames. However, if either locating mechanism is removed, then the material must be formed from one (or a combination of) continuous strip(s) to reduce the degrees of freedom in the system. It should be noted that the linear reference holes 4, 5 preferably lie on the two end sections unless there are overlapping (or another set) of holes to close the loop. Otherwise the position of the final joint will be undetermined. The use of overlapping holes on the closing joint allows the reference dimension to be the main diagonal of the panel, giving the greatest accuracy.

The concept of using known reference points to locate adjacent segments of the same frame can be extended to the interconnection of adjacent frames themselves. A plurality of individual frames can be joined together to form either larger frames as shown in Figure 15 or more complex assemblies such as three dimensional modules as shown in Figure 17. Larger frames themselves can be made using the method described but the use of a number of smaller frames has the advantages of handling ease and design flexibility - i.e. a wide variety of large frame designs can be produced using a library of simple smaller standard frames.

Conventionally, large frames and modules themselves need large complex jigs for accurate assembly. However, by using sub-frames and components with known, accurate reference locations 18, such as holes, for locating (using bolts or autolocating clinching, welding etc.), it is possible to construct large complex structures with virtually no jigging whatsoever. For example, by aligning punched holes of known location, panels or frames can be extremely accurately positioned with their neighbours as shown in Figures 16a and 16b. This means that on site erection is de-skilled, and also multiple panels or frames can be assembled into modules with great ease.

The assembly of such panels or frames into module form allows more of the construction to be done in the controlled environment of a production facility rather than a building site. This means that lead times are reduced and product quality is enhanced.

The simplest method involves the use of a number of identical wall panels or frames, coupled with appropriate floor and ceiling panels as shown in Figure

17. In this design, there is potentially poor load transfer between the adjacent panels or frames 19, 20 to stop the module from twisting. This is potentially a limitation on the design, as twisting during transit between factory and site can damage the decor and interior fittings.

An improvement to this basic concept is to ensure that the panels or frames on the roof and floor do not align to those on the walls as shown in Figure

18. This overlapping offers greater structural integrity than the previous designs as the end of each panel acts as a tie between the segments of the two panels that are attached to the ends of it. This therefore acts to prevent the panels from distorting.

However, any given module concept can either be constructed using conventional methods with individual sections (and therefore requiring jigs for the panels and further jigs to assemble these panels into modules) or by using the in-built geometry method of making sub panels. Indeed, the jig-less framing technique can be further extended to facilitate the assembly of three- dimensional modules without the need for three-dimensional jigging. By including reference holes or notches to align the faces of adjoining panels as shown in Figures 16a and 16b, the accuracy of their location is ensured. In particular, if a tool is used that aligns the holes and joins simultaneously, the assembly process is once again substantially simplified. The locations of all the holes, notches, folds and cuts can be a pre-determined function of the overall module (or just the panel) dimensions. It is possible to formulate simple design rules that take certain input parameters such as module length, height, floor loading (to determine the floor section depth) and horizontal centre spacing (to increase the module stacking height, the distance between vertical struts can be reduced) and automatically generate all the production parameters. This therefore substantially reduces the amount of detailed design work required; further reducing costs and lead times.

At the other extreme, having significantly de-skilled the assembly process, it is now possible to supply modules in kit form to be assembled on site. Kits can be supplied with pre-punched sections ready to assemble into sub-panels and subsequently into modules with great ease and speed. One of the limitations of section rolling is that the minimum length of a cut section tends to be longer than often required for some of the short members found in panels. Conventionally, panel assembly is possible by manually cutting standard section lengths into shorter lengths. This process is very labour intensive and prone to error. It is however possible to insert precision notches into the section such that the section is segmented into lengths of predetermined size. Therefore the overall strip is of a length suitable for automated cutting, but each segment of the section can be easily snipped to form a plurality of shorter individual sections. Each segment is punched with all the geometric locating holes necessary to quickly form the desired frame. If necessary, each segment can be marked during rolling so that each is identifiable after snipping with a product number, orientation etc. Transported in this form, it is possible to efficiently supply a large number of rapid assembly modules, which is useful in situations such as disaster relief. Continuous sections ready for folding into frames can be transported using much less space, and strips segmented ready for snipping into short lengths reduce the risk of loss or damage to components.

Another example where kit form may be advantageous is in the supply of roof trusses. Here a large number of trusses can be supplied on the back of a lorry in section form, flat packed ready for folding and fixing on site. Either a simple triangular truss 21a as shown in Figure 19 or a double triangle truss 21b with supporting central strut as shown in Figure 20 can be assembled from a single continuous section with no reference tooling, given that the predetermined hinge locations are sufficient to define the geometry.

Another example of a non-square frame made from a continuous section is a pentagonal frame for use in the assembly of small structures such as greenhouses as shown in Figure 21. However, two reference dimensions e.g. 22 and 23 are required here to ensure the correct geometry. A similar result with only one reference 24 can be achieved using a four member asymmetric frame that provides for an inclined roof as shown in Figure 22.

An asymmetric frame can visualise some of the advantages that are inherent in this concept. To make a number of panels of subtly varying dimensions requires nothing more than inputting the data into the computer that controls the section rolling mill (which can be part of a fully automated sales order processing process to further streamline the manufacturing process). As a result, complex structures (e.g. gradually inclining roofs) can be accommodated with ease.

As mentioned, it is possible to use the concept either in individual component form or for ultimate assembly ease, using a continuous segmented strip. It is also possible to combine elements of both an example of which is shown in Figures 23 and 24. Here, a continuous segmented strip 25 is used as the core of a lattice beam structure in conjunction with two external sections 26, 27. In this example, the hole positions are calculated so that the holes 28 in the segmented strip relate to the holes 29 punched in the individual sections.

Although metal is the preferred material for the methods described, wooden segments/sections could alternatively be used as the structural members.

It has been described how, by taking advantage of the computer controlled programming of modern section rolling equipment, the manufacture of a wide variety of frames and panels is facilitated by alterations in the software domain, rather than in tools and hardware. A method has been presented whereby geometric information traditionally embedded in an external reference frame, is in fact engineered in the product itself during production. Consequently the costs associated with the manufacture of such products is drastically reduced, as are the respective lead times.

In summary therefore, cold-formed sections for use in the construction of frames and panels are rolled from sections that have inherent geometric features that relate to the desired geometry of the resulting frame or panel. These sections can be formed into a frame using typically only one- dimensional reference (angular or linear) and no external jigging or clamping to produce an accurate component. Thus, a large variety of products can be manufactured quickly and accurately without the need for complex and expensive hardware or manufacturing tools. Such sections can be formed into panels which can be supplied in kit form to site, or can be accurately assembled without jigs into modules that can be fitted out if required prior to site delivery.

Claims

1. A method of forming a closed structure or frame of n sides, where n > 3, with respective predetermined angles between adjacent sides, comprising providing a closed structure or frame with respective adjacent sides being hinged together to provide approximately said predetermined angles between adjacent sides, and adjusting the angle between a number m of two adjacent sides of the structure or frame, where m > 1, so that respective reference positions of the relatively adjusted two adjacent sides are linearly spaced apart by a predetermined distance which corresponds to the predetermined angle of the structure or frame between said adjacent sides.

2. A continuous section for forming a closed structure or frame (hereinafter called a 'frame') of n sides, where n > 3, the section having a length substantially equal to the perimeter of the frame and being divided along its length by n-1 longitudinally spaced divisions therethrough into n interconnected segments, intended to form the frame sides respectively, in use, with adjacent segments foldable relative to one another at said divisions to form a predetermined angle of the frame, in use, with the two segments at respective opposite ends of the section, if n ≤ 4, and additionally a number of two adjacent segments, if n > 5, being provided with respective reference positions which, in the assembled frame, are spaced linearly apart by a predetermined distance when the angle between said two segments is equal to a correct predetermined angle of the frame, a minimum total number of said two adjacent segments being n-4.

3. A section as claimed in Claim 2, having or defining a base and a side, all reference positions being either in said sides of their respective associated segments or in said bases thereof.

4. A section as claimed in Claim 3, wherein said two segments at the respective opposite ends of the section are provided at their respective sides with alignment means which, when the two segments are folded so that their respective sides overlap, align when the angle between the two segments is equal to or is substantially equal to said correct predetermined angle of the frame, said alignment means being provided in addition to said reference positions which are linearly spaced apart in the assembled frame.

5. A section as claimed in Claim 4, wherein for any number of two adjacent segments, the segments are provided at their respective sides with alignment means which, when the two adjacent segments are folded so that their respective sides overlap, align when the angle between the two adjacent segments is equal to or is substantially equal to said correct predetermined angle of the frame.

6. A section as claimed in any one of Claims 1 to 5, wherein said reference portions and/or said alignment means are respective holes.

7. A section as claimed in Claim 3 or Claim 4, wherein said reference portions are respective holes in the sides of said two segments.

8. A section as claimed in any one of Claims 1 to 7, wherein said linear spacing apart of said reference positions corresponds to one side of a triangle, the other two sides of which are defined between the junction of said two segments or said two adjacent segments and said reference positions respectively, the angle opposite said one side of the triangle constituting said predetermined angle of the frame, in use.

9. A section as claimed in any one of Claims 1 to 8, wherein each division comprises a pair of aligned transverse cuts at respective opposite longitudinal edges/sides of the section.

10. A section as claimed in Claim 9, wherein each cut is rectangular.

11. A section as claimed in Claim 9, wherein each cut is V-shaped.

12. A section as claimed in Claim 9, wherein each cut has a narrow innermost portion and a V-shaped portion extending therefrom.

13. A section as claimed in any one of Claims 9 to 12, wherein at each division a fold line extends across the section from one of the pair of cuts to the other.

14. A section as claimed in Claim 13, wherein the fold line is in the form of perforations.

15. A section as claimed in Claim 3, wherein for said two segments at respective opposite ends of the section and/or any two adjacent segments, the free end of the side of one of the end segments, and/or the side of one of said two adjacent segments at a position adjacent the division therebetween, is swaged.

16. A section as claimed in any one of the preceding claims, having or defining a base and opposite sides upstanding therefrom.

17. A section as claimed in any one of the preceding claims, in which in at least one segment is defined at least one fixing hole which, in use, when the section is assembled as a frame, is intended to align with a hole in a segment of another such frame so that the frames can be connected together by fixing means passing through said aligned holes.

18. A closed frame formed from a section as claimed in any one of the preceding claims.

19. A structure comprising a multiplicity of frames as claimed in Claim 18, wherein respective engaging sides of two adjacent frames have aligned fixing holes therein through which fixing means are received to connect the two frames together.

20. A method of producing a continuous section for forming a closed structure or frame (hereinafter called a 'frame') of n sides, where n > 3, comprising forming a continuous metal section of a length substantially equal to the perimeter of the frame, dividing the section along its length by n-1 longitudinally spaced divisions therethrough into n interconnected segments, intended to form the frame sides respectively, in use, with adjacent segments foldable relative to one another at said divisions to form a predetermined angle of the frame, in use, and providing the two segments at respective opposite ends of the section, if n > 4, and additionally a number of two adjacent segments, if n > 5, with respective reference positions which, in the assembled frame, are spaced linearly apart by a predetermined distance when the angle between said two segments is equal to a correct predetermined angle of the frame, a minimum total number of said two adjacent segments being n-4.

21. A method as claimed in Claim 20, wherein said section is formed so as to have or define a base and a side.

22. A method as claimed in Claim 21 , comprising providing each reference position in said side of its associated segment.

23. A method as claimed in Claim 21 or Claim 22, comprising providing at the respective sides of said two segments at the respective opposite ends of the section alignment means which, when the two segments are folded so that their respective sides overlap, align when the angle between the two segments is equal to or is substantially equal to the correct predetermined angle of the frame, the alignment means being provided in addition to said reference positions which are linearly spaced apart in the assembled frame.

24. A method as claimed in Claim 23, comprising providing at the respective sides of any number of two adjacent segments alignment means which, when the two adjacent segments are folded so that their respective sides overlap, align when the angle between the two adjacent segments is equal to or is substantially equal to the correct predetermined angle of the frame.

25. A method as claimed in any one of Claims 20 to 24, comprising providing said reference and/or said alignment means as holes.

26. A method as claimed in any one of Claims 20 to 25, comprising providing said reference positions with a linear spacing apart, in the assembled frame, which corresponds to one side of a triangle, the other two sides of which are defined between the junction of said two segments or said two adjacent segments and said reference portions respectively, the angle opposite said one side of the triangle constituting said predetermined angle of the frame, in use.

27. A method as claimed in any one of Claims 20 to 26, comprising forming each division as a pair of aligned transverse cuts at respective opposite longitudinal edges/sides of the section.

28. A method as claimed in Claim 27, comprising forming each cut of rectangular shape.

29. A method as claimed in Claim 27, comprising forming each cut of V-shape.

30. A method as claimed in Claim 27, comprising forming each cut with a narrow innermost portion and a V-shaped portion extending therefrom.

31. A method as claimed in any one of Claims 27 to 30, comprising forming at each division a fold line extending across the section from one of the pair of cuts to the other.

32. A method as claimed in Claim 31 , comprising forming the fold line as a series of perforations.

33. A method as claimed in Claim 21, comprising swaging the free end of the side of one of the two segments at respective opposite ends of the section and/or swaging the side of one of any two adjacent segments at a position adjacent the division therebetween.

34. A method as claimed in any one of Claims 20 to 33, wherein the section is formed so as to have or define a base and opposite sides upstanding therefrom.

35. A method as claimed in any one of Claims 20 to 34, comprising forming at least one segment with at least one fixing hole which, in use, when the section is assembled as a frame, is intended to align with a hole in a segment of another such frame so that the frames can be connected together by fixing means passing through said aligned holes.

36. A method as claimed in any one of Claims 20 to 35, wherein the reference positions are produced during rolling of a metal strip to form said section.

37. A closed frame formed from a section produced by the method of any one of Claims 20 to 36.

38. A structure comprising a multiplicity of frames as claimed in Claim 37, wherein respective engaging sides of two adjacent frames have aligned fixing holes therein through which fixing means are received to connect the two frames together.

39. A method of forming a closed structure or frame (hereinafter called a 'frame') of n sides, where n > 3, from n separate side segments, comprising providing the side segments with respective predetermined hinge positions at their respective opposite ends, providing a number of two adjacent ones of the side segments additionally with respective reference positions, forming a closed hinged frame of said side segments by hinging adjacent side segments together at their respective overlapping ends with respective hinge positions of the adjacent side segments being aligned, and arranging the adjacent side segments of each of said number of two adjacent side segments at a correct predetermined angle of the frame by spacing the reference positions of the two adjacent side segments linearly apart by a predetermined distance, the mi mum total number of said two adjacent side segments having said reference positions being n-3.

40. A method as claimed in Claim 39, comprising providing said hinge positions as holes.

41. A method as claimed in Claim 39 or Claim 40, comprising providing said hinge positions in respective sides of the side segments.

42. A method as claimed in any one of Claims 39 to 41 , comprising providing said reference positions as holes.

43. A method as claimed in any one of Claims 39 to 42, comprising providing said reference positions in respective sides of the side segments.

44. A method as claimed in any one of Claims 39 to 43, wherein the reference positions are produced in each side segment during its rolling from a metal strip.

45. A metal side segment for use in carrying out the method of Claims 39 to 44.

46. A closed metal frame formed by the method of any one of Claims 39 to 45.