WO2009010793A2 - Sheet material incorporating fold lines - Google Patents

Abstract

The present invention provides a substantially flat sheet material which is arranged to fold to form a corner module(200). The sheet comprises a face (101) and an underside(103) and at leastfour convergent fold lines (L 1, L 2, L 3, L 4) defining four stiff sections in the sheet (102,106,108,110). Three of the fold lines (L 1, L 2, L 3) are arranged 5 to allow the sheet to fold so as to reduce the angle between the faces of adjacent sections(102,106,108,110), and one of the fold lines (L 4) is arranged to allow the sheet to fold so as to increase the angle between the faces of adjacent sections. To be accompanied, when published, by Figure 3.

Description

SHEET MATERIAL INCORPORATING FOLD LINES

The present invention relates to a sheet material incorporating fold lines arranged to form at least one corner module. In particular, but not exclusively, the sheet material may be a stiff material such as polypropylene.

In order to facilitate storage of occasionally used items, it is often desirable that such items fold flat. For example, folding chairs and tables are well known. Such folding items are often made from two or more components requiring assembly.

Recently, there have been developments in 'living hinges'. A living hinge is a thin, flexible portion of material that joins two relatively rigid bodies of the same material together. When formed in an appropriate material (of which polypropylene and polyethylene are both examples) the hinge can be repeatedly folded without significant deterioration that would occur in other materials due to fatigue. This allows an object to bend about an integral 'hinge' which avoids the need for multiple components and assembly and can allow easier cleaning and maintenance.

An example of such a hinge can be seen on a folding chopping board known as Chop2Pot™ produced by Joseph Joseph Limited, 121 Oxo Tower Wharf, Bargehouse Street, London, SE1 9PH, United Kingdom. The hinges allow the board to fold so as to form a chute for transferring chopped ingredients into a saucepan or the like.

There exists a need for items which are easy to use, easy to store, easy to manufacture, easy to transport and/or easy to clean.

According to one aspect of the present invention, there is provided a substantially flat sheet material arranged to fold to form a corner module, the sheet comprising a face and an underside and further comprising at least four convergent fold lines defining four stiff sections in the sheet, wherein three of the fold lines are arranged to allow the sheet to fold so as to reduce the angle between the faces of adjacent sections and one of the fold lines is arranged to allow the sheet to fold so as to increase the angle between the faces of adjacent sections.

It will be appreciated that the term 'stiff' as used herein means 'stiff relative to the fold line'. However, in preferred embodiments, the sections may be substantially rigid. In preferred embodiments, the sheet material is substantially continuous. In one embodiment, the corner module is formed with four fold lines and the sections comprise a base section, a side section, an end section and a corner section, the sections being arranged such that:

the base section is connected to the end section via the first fold line and to the side section by the second fold line,

the corner section is connected to the side section via the third fold line and to the end section by the fourth fold line,

wherein the fold lines are arranged such that, as the corner is formed, the angle between the face of the corner section and the face of the side section decreases, the angle between the face of the end section and the face of the corner section increases, the angle between the face of the end section and the face of the base section decreases, and the angle between the face of side section and the face of the base section decreases,

such that, once the corner is formed, the angle between the face of the corner section and the face of the side section is less than 90 degrees.

In some embodiments, the angle may be less than 60 degrees, and may be between 5 degrees and 0 degrees.

In one embodiment the fold lines converge to a single point. In other embodiments, one or more of the fold lines may be off-set from a point where two or more of the fold lines converge. Off-setting one or more fold lines may be advantageous as it may prevent the faces of the sections from colliding as a corner module is formed. Therefore, providing an offset may be particularly advantageous where the angle is significantly less than 90°, and indeed as the angle approaches 0°.

In one embodiment, the sheet is formed of a single material. The fold lines may be formed in weakened regions of the material. Providing a sheet made of only one material makes the sheet easy to manufacture. The weakened region may, for example be a perforated region.

In one embodiment, the sheet comprises a material with a thickness and the fold lines may be formed in regions of reduced thickness. In such embodiments, the fold lines may be formed by V-shaped grooves cut away from the face or from the underside of the sheet. In some embodiments, the V-grooves may all be formed from one side, i.e. either the face or the underside. This may allow, for example, a waterproof container to be formed. In other embodiments, some of the V-shaped grooves may be formed on one side (the face) and some on the other side (the underside). Having at least one fold line on the face and at least one fold line on the underside may be advantageous as the sheet may resist being bent back on itself in its flat state and so have the feel of a semi- rigid sheet.

In one embodiment, at least one fold line is inset from the face or the underside of the sheet. In particular, where the fold line is provided in a hinge comprising a thin section of material, this section may be formed by reducing the depth of the material from both the face and the underside of the sheet. Alternatively, as the fold line will form approximately half way though the thickness of the hinge, the fold line may inset by providing hinges of different thicknesses. This moves the fold line onto a different plane from fold lines which are not inset. This in turn allows faces between which the angles are reducing to come together with less resistance.

The material may be, for example, plastic. In preferred embodiments, the plastic has living hinge properties. Polypropylene and polyethylene are examples of such plastics.

The fold lines may be formed by providing thinner regions of the material (when compared to the thickness of the stiff sections). Where the sheet is formed of a plastic material it may be readily manufactured using injection moulding, machining techniques and the like. It will also be easy to clean, for example in a dishwasher. If the material is a plastic material, it is advantageous to form the sheet such that the plastic flows across the fold line rather than parallel to it as this will increase the strength and durability of the hinge.

In a preferred embodiment, the material is polypropylene. Polypropylene provides a versatile material which is easy to mould and/or machine and which is easy to clean. In addition, polypropylene has the ability to form living hinges in thin sections that allow repeated folding, whether injection moulded, machined, cast or the like. It is a relatively hard and durable plastic that can be 'food safe', dishwasher safe and microwave safe.

The corner module may be arranged to form such that two of the sections are brought into (or close to) face-to-face contact. This allows the corner module to define an internal surface between the faces of the sections.

In one embodiment, the corner section is brought into (or close to) face-to-face contact with the side section (i.e. the angle between the face of the corner section and the face of the side section is approximately zero). This allows the corner module to define an internal surface between the faces of the base section, the side section and the end section.

In some embodiments, it is preferable that the fold lines are repeatedly foldable. This is advantageous as it allows the corner module to be formed and collapsed (i.e. the sheet may be folded and laid flat) repeatedly. In such embodiments, the fold lines may be formed in living hinges. Used herein, the phrase 'living hinge' means a thin, flexible portion of material (for example a web of material) that joins two relatively stiff or rigid bodies of the same material together. In alternative embodiments, the hinges may comprise flexible materials such as fabric, leather or the like, or may comprise plastic interlocking hinges, metal piano hinges or the like.

The sheet may comprise more than one corner module. In some embodiments, the sheet may be arranged to form two, three, four or more corner modules. Providing a sheet with the ability to form more than one corner module allows the sheet to form open or closed polyhedrons, which are versatile in their uses. For example, the illustrated embodiment described hereinafter comprises four corner modules and allows a substantially frusto-pyramidal shape to be formed from a substantially flat sheet. However, it will be appreciated that other shapes could be formed, including cuboids and the like.

In one embodiment, the sheet is arranged such that it is stackable with other such sheets when in the flat state. This makes the sheet easier to transport, store and display. In order to facilitate stacking, the sheet may comprise a means of registering one sheet against another sheet. The sheet may for example comprise projections and recesses arranged such that the projections of one sheet cooperate with the recesses of another sheet. These projections and recesses may serve additional purposes such as feet, handles or the like.

In one embodiment, the sheet comprises fastenings arranged to hold the corner module in its folded position. This is advantageous as it allows a stable corner module to be formed and the sheet will resist internal stresses or external forces to resume its flat state. The fastenings may include, for example, magnets, hooks and catches, ties, poppers, nuts and bolts, Velcro®, or the like. In other embodiments, the fastenings may include permanent fixings such as glues, welding, or the like. In preferred embodiments, the fastenings are arranged such that they are substantially within the profile of the sheet when it is in its flat state. This allows for easier storage of the sheet. According to one aspect of the invention, there is provided a collapsible container made of a sheet material incorporating living hinges which, when collapsed, is substantially flat. Preferably, when in its flat state, the sheet material is a single layer.

According to one aspect of the invention, there is provided a collapsible object made of a sheet material incorporating fold lines arranged to form at least one corner module as described above. In some embodiments, the object is a container.

According to one aspect, the invention provides a collapsible item of kitchenware. In such embodiments, it is particularly advantageous to manufacture the item of a material which is food safe and easy to clean, preferably in a dishwasher. It may also be advantageous to provide a material that is oven and/or microwave safe. It may be particularly advantageous that such an embodiment folds flat as this allows for easy storage.

According to one aspect, the invention provides a collapsible colander arranged such that, when in the collapsed position, the colander comprises a substantially planar sheet incorporating fold lines. The colander may be formed of a sheet material incorporating one or more corner modules as described above.

Any of the aspects of the invention described above may incorporate the features of any other aspect of the invention.

Embodiments of the invention are now described, by way of example only, with reference to the following figures of which:

Figure 1 schematically shows fold lines arranged to allow a corner module to be formed from a flat sheet;

Figure 2a-2c show the formation of the corner module using the fold lines shown in Figure 1 ;

Figure 3 schematically shows fold lines arranged to allow a container to be formed from a flat sheet by including four of the corner modules of Figure 1 ;

Figure 4 shows the upper face of a colander incorporating one embodiment of the invention in a collapsed/flat state;

Figure 5 shows the underside of the colander of Figure 4 incorporating one embodiment of the invention; Figure 6 shows the upper face of a colander as shown in Figure 4 along with cross sectional views of the colander;

Figures 7 and 7 a show detail of a corner module of Figure 6;

Figures 8a to 8d show detail of the living hinges incorporated in the colander;

Figure 8e shows detail of a variation of the corner module of Figure 6;

Figures 9 and 9a show a perspective view of the upper face of the colander;

Figure 10 shows a hook according to one embodiment of the invention;

Figure 11 shows a catch according to one embodiment of the invention;

Figure 12 shows a perspective view of an assembled colander;

Figures 13a to 13d show various arrangements of fold lines arranged to form corner modules;

Figure 14 schematically shows fold lines arranged to allow a corner module to be formed from a flat sheet;

Figures 15a to 15c show the formation of a corner module using the fold lines shown in Figure 14;

Figures 16a to 16d show a device utilising a corner module; and

Figures 17a and 17b show underside and magnified views of the device of Figures 16a to 16d.

In order to illustrate one embodiment of the invention, reference is made to Figure 1 which shows a rigid plane P incorporating fold lines arranged to form a corner module. For the purpose of the following explanation the plane P is considered to have zero thickness.

The plane P comprises four fold lines L₁, L₂, L₃, L₄ which all converge at one junction J. This divides the plane P into four rigid faces: a base B (between L₁ and L₂), a side S (between L₂ and L₃), a corner C (between L₃ and L₄) an end E (between L₄ and L₁). Each face extends though an angle (i.e. the angles between the four fold lines L₁, L₂, L₃, L₄), labelled A₆, A_s, A₀ and A_E respectively. In Figures 1 to 3, the angles between the four fold lines are A₆ = 90°, A_s = 135°, A_E = 1 14.79°, A₀ = 20.21°, although it will be appreciated that other sets of angles are possible and that changing the angles A₆, A_s, A_c, A_E between the four fold lines L₁, L₂, L₃, L₄ in the flat position results in changes to the angles between the four faces B₁S₁C₁E in the folded position.

Figure 1 also shows mirror lines M₁ and M₂ which are perpendicular to L₁ and L₂. The set of fold lines L₁, L₂, L₃, L₄ arranged to form a corner module 200 can be mirrored about the mirror lines M₁ and M₂ or rotated, as is discussed in relation to Figure 3 below.

Figures 2a to 2c show the stages in folding the fold lines L₁, L₂, L₃, L₄ to form a corner module 200. In Figure 2a, the plane P is shown flat. In Figure 2b, the base B is held stationary while the end E is folded around L₁ (so that the angle between the base B and the end E faces is reducing). This forces the corner face C to move upwards too, whilst rotating it outwards about L₄ (so that the angle between the end face and the corner face is increasing). This in turn lifts the side face S via fold line L₃, causing it to rotate about L₂ (so that the angle between the base face B and the side face S is reducing). As the corner module 200 folds, the angle between the corner face C and the side face S reduces from 180° to 0° (i.e. until they are in contact with each other). This is the fully folded position, as shown in Figure 2C.

It should be noted that for the corner module 200 to fold in the way that is described above, the following rules should apply:-

• A_E + Ac < 180°

• A₀ < As

• (As - Ac) > the magnitude of (A₆ - A_E)

Although these rules describe the theoretical ranges of possible angles, performance of the corner module 200 may reduce as the angles approach the end points of these ranges.

Figure 3 shows a plane P incorporating four sets of fold lines L₁, L₂, L₃, L₄ capable of forming corner modules 200. Two of these sets are as have been described above (shown top right and bottom left on Figure 3) and two are two mirror versions of this described set. When these corner modules 200 are folded, the plane P will form a five- sided container shape (i.e. a base and 4 sides). However, the skilled person will appreciate that other shapes may be formed by using more or less sets of fold lines capable of forming corner modules 200.

Although the foregoing serves to illustrate the principle of allowing corner modules 200 to be formed in a plane P, it will be appreciated that in reality materials have a thickness. If the plane P is considered to be the face of a material having an appreciable thickness, it becomes apparent that the faces B, S, C and E cannot all have edges which butt up against each other at the fold lines L₁, L₂, L₃, L₄. If the fold lines L₁, L₂, L₃, L₄ are all on the top surface, the corner module 200 will no longer fold as the rigid section edges at the fold line L₄ between the edge face E and the corner face C will bottom out on each other immediately. To enable folding movement to take place, clearance must be given to the section edges at at least this fold line L₄. This could be achieved, for example, by forming the two section edges on the reverse side of the fold line L₄ between the edge face E and the corner face C at an angle to create a V-shaped groove, where the V- groove angle is greater or equal to the angle it needs to fold by (although of course less than 180°). It will of course be understood that, for example, if the material is very thin or is compressible, the V-grove may not be required.

Similar V-grooves may be formed in the other three fold lines L₁, L₂, L₃, L₄ but this is an aesthetic, rather than a technical, consideration as these fold lines are "opening" (i.e. the angles between adjacent faces are decreasing) rather than "closing".

One alternative embodiment of the present invention is shown in Figures 4 to 12. These Figures show some exemplary measurements in millimetres. For the sake of the clarity of the Figures, all features are not labelled on all Figures.

In this embodiment, the fold lines L₁, L₂, L₃, L₄ are not all on one face of the plane P, as was described above. These Figures show a collapsible colander 100 incorporating four sets of fold lines L₁, L₂, L₃, L₄ capable of forming corner modules 200. The colander 100 is made of a single piece of moulded polypropylene and has a face 101 shown in Figure 4 and an underside 103 shown in Figure 5. At each corner, the four sections B, S, C, E are connected at fold lines L₁, L₂, L₃, L₄ (as marked in the top left hand corner of Figure 4) by a thin section of the material. In these thin sections (which are shown in cross section in Figures 8a to 8d), the material has the ability to form "living hinges" 800a, 800b, 800c, 80Od that allow the material to bend repeatedly at any one fold line L₁, L₂, L₃, L₄.

Referring principally to Figure 4, the colander 100 comprises a substantially octahedral planar polypropylene sheet. The colander 100 comprises a square base section 102 at its centre defined by four fold lines. Two of these fold lines are of a first type (L₁) and two of the fold lines are of a second type (L₂), as will be described in greater detail below.

Eight hinged sections are also provided. The hinged sections comprise two end sections 108 which are connected to the base section 102 by the first type of fold line L₁, and two side sections 106, which are connected to the base section 102 by the second type of fold line (L₂). The side section 106 and the end sections 108 are substantially hexagonal in shape. The hinged sections further comprise four corner sections 110, which are substantially triangular in shape. Each corner section 1 10 is joined to a side section 106 via third type of fold line (L₃) and to an end section 108 via a fourth type of fold line (L₄).

As is shown in detail in Figure 8a to 8d (see the cross sections marked on Figure 7), in this embodiment, fold lines L₁ and L₂ are formed in face 101 of the colander 100 as follows. V-grooves 802a, 802b are formed with their apex toward the underside 103 of the colander 100 as shown in Figures 8a and 8b (these hinges will "close" when the colander 100 is assembled, so clearance is required). The angle of these V-grooves 802a, 802b is greater than or equal to the fold angles between the base section 102 and the end section 108 and between the base section 102 and the side section 106 respectively.

As can be seen most clearly from Figures 7a and 13d, the fold line L₄ is positioned such that it does not intersect at the junction of the fold lines L₁ and L₃ (in contrast to the example of Figures 1 to 3). This is described in greater detail below with reference to Figures 13a to 13d.

A V-shaped groove 802c, 802d is formed on the underside 101 of the colander 100 along L₄ and L₃ with its apex towards the face 101 of the colander 100 (see Figures 8c and 8d). As described above, the groove 802c at L₄ is necessary to allow the folding process to be carried out but the groove 802d at L₃ is added principally for aesthetic considerations. The formation of these four intersecting V-grooves results in a hole in the sheet material. In the illustrated embodiment, this hole has been trimmed to form a substantially lozenge shaped hole 122 at the junction of the V-grooves. The hole 122 has been extended in the direction of L₁ to allow relative flexing between the base section 102 and the end section 108. This assists with reducing the internal stresses that result when the colander 100 is in between its flat and folded states. Therefore, extending the hole 122 reduces the 'snap' force felt as the colander 100 is folded but helps to avoid permanent damage to any of the hinges 800a-d. Figure 8e shows a detailed view of a variation of the corner module of Figure 6. Cutout 450 is extended along hinges L₁ and L₂ (in contrast to the cut-out 122 of Figures 7 and 7a which only extends along hinge L₁) to provide a substantially L-shaped hole at the junction of the V-grooves. This performs in the same way as the lozenge shaped hole 122 (as described above) but, by shortening hinge L₂, it also has the effect of allowing relative flexing between the base 102 and side 106.

If the colander 100 is folded "incorrectly" (i.e. folded in any way other than as described herein), large stresses can be generated in some of the hinges. An example of "incorrect" folding is where the side 106 is bent relative to the base 102 so that the angle BS is substantially larger than 180°. To reduce the likelihood of such stresses damaging the hinges, stress relief slots 451 linked to the lozenge shaped 122 or L-shaped 450 holes may be provided. These slots enable relative flexing to take place between the side panel 106, corner panel 1 10 and the connecting hinge L₃ Stress relief slots may also or alternatively be positioned in the end 108 and/or corner 1 10 panels to provide stress relief in the respective hinges. The slots may be straight, curved or shaped in other appropriate ways to perform the described function.

The colander 100 also comprises four hooks 1 12 (two in each of the end sections 108) and four catches 1 14, which are described in greater detail with reference to Figures 10 and 1 1 below. The colander 100 further comprises a plurality of drainage holes 116 distributed over the base section 102 and the regions of the hinged sections 106, 108, 1 10 towards the base section 102, and two handles 1 18, which are formed as cut-out portions in the end sections 108.

Four feet 120 are formed in the base section 102. As can be seen from Figures 6 and 9, the feet 120 are moulded such that a hollow formed on the upper side (the face 101 ) forms the feet 120 on the underside 103. This contributes to the stability of a stack of colanders 100 in their flat state, in that the feet 120 of one colander 100 rest in the hollows of the colander 100 directly below it. In addition, the handles 1 18 are formed with a sloped profile 600 and a lip 602 protruding from the underside 103 (see the section y-y in Figure 6), the arrangement being such that, when stacking colanders 100 in their flat state, the lip 602 of one colander 100 may rest within the profile 600 of the handle 1 18 of the colander 100 directly below.

By having hinges 800a, 800b, 800c, 80Od on both sides of the colander 100, the colander 100 resists being bent back on itself in its collapsed state and so has the feel of a semi-rigid sheet. When all the hinges 800a, 800b, 800c, 80Od are on one side, this results in the feel of a floppy sheet made up of rigid panels, which may be desirable in other embodiments.

In addition, in the flat and folded positions, the geometry and angles of the four fold lines on each side of the sheet are stable i.e. without internal stresses. However, during the folding operation, the fold lines L₁, L₂, L₃, L₄ become "misaligned" relative to each other which causes the four sections 102, 106, 108, 1 10 to flex individually creating internal stress, which is an unstable state. This gives the corner module a slight "snap feel" as it moves between the flat and folded positions.

Referring again to Figure 8a-d, each of the hinges 800a, 800b, 800c, 80Od has a length. The length depends on the angle through which the hinge 800a, 800b, 800c, 80Od has to bend. Therefore, in this example, the hinge 80Od at L₃ (see Figure 8d) is the longest as L₃ bends though 180°, a greater angle than any other hinge.

In addition, the living hinges 800a, 800b, 800c, 80Od in which the fold lines L₁, L₂, L₃ and L₄ are formed are approximately 0.5mm thick. Therefore, looking in cross section, when the living hinges bend, the outer part of the hinge is in tension and the inner part is in compression. Between these two parts is the neutral axis of the hinge where, in theory, there is no tension or compression. As the hinges 800a, 800b, 800c, 80Od have a thickness, this neutral axis (i.e. the fold line) is slightly inset from the sheet faces. Therefore, when the colander 100 folds to form the corner module 200, the corner face C and the side face S close inwards and interfere with each other. This has the effect of making the mechanism "resist" folding and smother the "positive snap feel" provided by having fold lines L₁, L₂, L₃, L₄ arranged on either side of the colander 100. While this may be desirable in other embodiments, in the present embodiment a snap feel is desired. As can be seen from Figures 8a-8d, the hinges 80Od, 800c at L₃ (Figure 8d) and L₄ (Figure 8c) are formed by a V-shaped groove 802d, 802c from the underside 103 and a substantially rectangular groove 804d, 804c on the face 101.

Similar rectangular grooves can be seen on L₁ (Figure 8b) and L₂ (Figure 8a) in the underside 103. This results in the fold lines (and in particular L₂) being inset.

The reason for the off-setting of L₃ and L₄ and the insetting of L₂ is explained as follows with reference to Figures 13a to 13d.

The insetting of L₂ contributes to the colander 100 folding more readily as explained below. The insetting of the other fold lines L₁, L₃, L₄ is more for aesthetic rather than technical reasons (although there may be a technical advantage in defining the fold lines L₁₁ L₃₁ L₄ ) In the example of the 'one-sided' corner module described with reference to Figures 1 to 3 and now with reference to Figure 13a, hinges 800a-d are all on the face of the sheet and are presumed to have an infinitely small thickness such that the actual point of folding in each hinge 800a-d (i.e. the neutral axis, and therefore the fold lines L₁, L₂, L₃ and L₄) is on the face 101 of the sheet. Therefore, in this example, the fold lines L₁, L₂, L₃, L₄ and the hinges 800a-d are coincident. In this version, all four hinges 800a-d meet at one single point and the corner module 200 can fold freely until corner section 1 10 and sides S come into face-to-face contact.

In such an 'infinitely thin hinge' version of the 'two-sided' corner module 200 (see Figure 13b), hinges/fold lines L₃ and L₄ are still on the face 101 , but hinges/fold lines L₁ and L₂ are moved to the opposite side of the sheet (the underside 103). Hinges/fold lines L₁ and L₂ (on the underside) still meet at one point and, when viewed normal to the face 103, L₃ also passes through this point (albeit on the other side of the sheet, the face 103). Hinge/fold line L₄ no longer coincides with this point, but is shifted a distance along the length of L₁. This results in a configuration of fold lines L₁, L₂, L₃, L₄ that is geometrically stable in both the flat and folded positions. However, when between the flat and folded positions, the fold lines L₁, L₂, L₃, L₄ are not geometrically correct which results in internal stresses forming within the corner module 200 and an unstable state.

There are two main differences between the 'two-sided' corner module 200 compared to the 'one-sided' version: Firstly, the 'two-sided' version resists being folded in the wrong direction (i.e. when the face angle between base B and end E is larger than 180°); and secondly, due to the internal stresses during folding (as described above) the 'two-sided' version is only stable in the folded and flat positions, resulting in a positive 'snap' feel when folding and unfolding the corner module 200. Which version is desirable depends on the application to which the corner module 200 is being put.

In these 'infinitely thin hinge' models of the 'one-sided' and 'two-sided' corner modules (described above) the hinges are presumed to have zero thickness and are therefore coincident with the fold lines but, in practice, a hinge 800 has a finite thickness. If their thickness is significant, the neutral axis (i.e. the fold line) of each hinge 800 can no longer be considered to reside on the actual surface 101 , 103 of the sheet, but instead is inset by a small distance into the sheet (approximately half the thickness of the hinge 800). This means that as the corner module 200 (whether one-sided or two-sided) approaches the fully folded position the faces of corner section 1 10 and side section 106 will collide, resulting in a resistance to folding that, in at least the present embodiment, is undesirable (although it may be desirable or acceptable in other embodiments). In a 'thicker hinge' one-sided version (Figure 13c), one way of correcting this is to 'offset' the fold lines L₃ and L₄ along the length of L₁, each by a small distance such that they no longer meet at the junction of L₁ and L₂, and to 'inset' the fold line L₁ by a small distance further into the sheet, such that it no longer resides on the same plane as the neutral axes L₂, L₃ and L₄ of the other hinges. The term 'thicker hinge' is intended to describe a hinge having an appreciable thickness, e.g. 0.5mm in the present embodiment, such that the fold line can no longer be considered to coincide with the hinge, but instead lies on the neutral axis within the hinge.

Applying the same solution to the illustrated colander 100 (i.e. a 'thicker hinge' two-sided version, Figure 13d), fold lines L₃ and L₄ are again 'offset' along the length of L₁ (such that L₃ no longer passes through the junction of L₁ and L₂), and L₂ is 'inset' from the underside 103 (i.e. moved towards the face 101 ) by a small distance such that it no longer resides on the same plane as the fold line of L₁. This results in the same relative adjustment between L₁ and L₂ as in the 'thicker hinge' one-sided model shown Figure 13c. In addition, L₄ is shifted along L₁ as described above with reference to Figure 13b.

In any arrangement of hinges 800 the actual dimensions of these corrective 'offsets', 'shifts' and 'insets' can be calculated, for example using parametric 3D CAD software or empirically.

In the present colander 100 embodiment, a fastening means is used to keep the corner 1 10 and side 106 faces in contact and the corner modules 200 closed. As can be seen from the Figures, the fastening means in this embodiment comprise a hook 112 and catch 1 14 arrangement positioned at each of the four corners. The hook 112 is shown in detail in Figure 10 and the catch 114 is shown in Figure 1 1. The hook 112 is formed from a substantially rectangular member which is cut out on three sides. It is positioned such that its fixed side is on an end portion 108 and each hook 112 extends into a corner section 1 10. On the underside 103 of the colander 100 (see Figure 5), the hook 1 12 has a substantially 'S' shaped profile. The catch 1 14 comprises a cut out portion which, as can be seen from Figure 1 1 , is shaped at one edge so as to form a point 124. The catches 114 are positioned towards the outer corners of the hexagonal side sections 106.

The arrangement is such that, when the corner module 200 is formed, the hook 112 enters the catch 1 14. The hook 1 12 is displaced from the plane of the end section 108 by the cooperation between its S-shaped profile and the point 124 of the catch 114. However, once the first half of the S-shaped profile has passed the point 124, the resilience of the polypropylene material causes the hook 1 12 to return to the plane of the end section 108. The corner module 200 is then held fast.

The corner module 200 could be unfastened either by applying pressure transversely to the hooks 1 12 or by pulling the side sections 106 apart, causing the hook 1 12 to slide over the point 124 of the catch 1 14. If disassembly occurs by pulling apart the side sections 106, it will be appreciated that one pair of hooks 112 will disengage with the catches 1 14 in one side section 106 before the other side section 106 is disengaged. By positioning the hook 112 on the underside 103 of the colander 100, disassembling the colander 100 is made easier as the disengagement of one side section 106 will tend to cause a change in the geometry of the colander 100 pushing out the end sections 108 near the disengaged side section 106. This in turn tends to ease the disengagement of the other pair of hooks 112, as the hooks 112 are slightly rotated.

The colander 100 is shown assembled with all the hooks 1 12 engaged in catches 114 in Figure 12. The colander 100 is ready for use in draining or washing vegetables or the like. It will be appreciated that the engagement of the hooks 1 12 prevent the colander 100 from assuming its collapsed or flat state when material (which may be relatively heavy) is placed therein.

Figure 14 shows a rigid plane P incorporating fold lines arranged to form a variation of the corner module 200. For the purposes of the following explanation the plane P is considered to have zero thickness.

Fold lines L₁, L₂, L₃ and L₄ converge at a junction J and divide the plane into four rigid sections: a base B (between L₁ and L₂), a side S (between L₂ and L₃), a corner C (between L₃ and L₄) and an end E (between L₄ and L₁). Each section extends through an angle (i.e. the angles between the four fold lines L₁, L₂, L₃ and L₄), labelled A₆, A_s, A_c and A_E respectively.

In the corner module 400 shown in Figure 14 fold lines L₂ and L₄ are arranged such that the sum of angles A_E and A₆ is 180° and the sum of angles A₀ and A_s are 180°. The four fold lines, L₁, L₂, L₃ and L₄ intersect at the same junction (J). This arrangement of fold lines allows the plane to fold in a similar fashion to the previously described configurations, but provides a variation in the angular arrangement of the folded plane.

When sections B and E are arranged to be co-planar, fold lines L₂ and L₄ are collinear and create a folding axis along the fold line L₂ - L₄. For convenience, when L₂ and L₄ are collinear the symbol L₂₄ will be utilised. When L₂ and L₄ are collinear, sections S and C are coplanar with one another. L₂₄ thus forms a hinge between a section formed of B and E and a section formed of S and C.

Figure 15a shows the plane of Figure 14 in a flat position (P₀). Figure 15b shows the plane of Figure 14 in an angled position (P₂) with the sections C and S raised about L₂₄ by an angle X to the plane formed by sections B and E. When X is greater than 0°, sections B and E must remain co-planar and sections C and S must remain co-planar. Thus, when X is > 0°, fold lines L₁ and L₃ become 'locked' and the angle between the sections joined by those hinges is fixed. The plane behaves as two panels BECO_MBIN_ED and SCcoMBiNED, connected by the fold line L₂₄.

With angle X set to 0° fold lines L₁, L₂, L₃ and L₄ are 'unlocked' and the sections can be moved relative to each other to fold the sheet into a folded position (P₁) shown in Figure 15c. To fold the plane into the folded position (P₁), the angles BS, SC and EB ('angle BS' and similar terms are utilised herein to describe the angle between the identified sections) are reduced, while the angle CE is increased.

In order to move from position P₂ to position P₁, the sheet must pass through position P₀, where faces B, S, C and E are coplanar.

In an example of a corner module 400, angles A_E and A₆ may be 90°, A₀ may be 45° and As may be 135°. However, other angles may be used providing that the previously described rules (as stated for corner module 200) are met.

As explained above, the plane of Figure 14 is assumed to have zero thickness and be rigid. In order to move from P₂ to P₁ (and vice versa) the sheet must pass through P₀ in which all sections are perfectly coplanar. However, in a practical implementation (that is, a physical item having fold lines according to Figure 14) the plane and fold lines will have a finite thickness and a degree of flex which means that the faces do not all have to be perfectly coplanar to move from P₂ to P₁ and L₂₄ does not have to be exactly collinear. The terms BECO_MBIN_ED and SCCO_MBIN_ED are thus intended to refer to the sections being sufficiently coplanar, and L₂₄ to refer to fold lines L₂ and L₄ being sufficiently collinear, to allow movement from P₂ to P₁.

Figure 16a shows a chopping and rinsing device incorporating corner module 400. The corner module of the device is a mirrored version of that shown in Figures 14 and 15a-c but operates according to the same principles. For convenience like references are utilised in Figures 14, 15a-c and 16a-d. As explained above in relation to other embodiments, panels B, S, C and E are formed of a rigid sheet material such as polypropylene and hinges at fold lines L₁, L₂, L₃ and L₄ may be formed as living hinges between those panels. Where angles are described between panels having a finite thickness, the angles are measured between faces of those panels.

Figure 16a shows the device in a flat position (P₀) with panels B, S, C and E coplanar. In this position the device can move to the angled position (P₂) shown in Figures 16b and 16d or the folded position (P₁) shown in Figure 16c, as has been described above in relation to Figure 15a-c. Panels B and E are substantially flat surfaces, configured for use as cutting or chopping surfaces. Panel S has a plurality of holes 300 through the face and a catch hole 301. A hook 302 is provided for releasably locking the device in position (P₁).

In position P₂ the panels B and E may be positioned on a surface and the faces of panels B and E may be utilised as a cutting and chopping surface. With the device in position P₂, the hinge at fold line L₁ is locked, thus retaining BE_COMBINED in the coplanar position.

From position P₀ the device may be moved to position P₁ (Figure 16c) by reducing angle BE. As the device moves to position P₁, angle CE increases and the angles BS and SC reduce. As the device moves into position P₁ the hook 302 engages with the catch hole

301 to releasably lock the device in position P₁. In position P₁ the device can be used to rinse or drain items contained in the volume defined by panels B, E and S. By appropriate angling of the device, water poured onto the items flows out of the drainage holes 300, and through the hole 303 present at the intersection of hinges at fold lines L₁,

L₂, L₃ and L₄. The distal end of the volume from panel S is open, such that items in that volume can be tipped out by angling the device in that direction.

With the device in position P₂, panel BE_COMBINED may be positioned on a surface and the upper faces of those panels used as a cutting or chopping surface. In that position, panel SC_COMBINED is free to rotate around the hinge at the fold line L₂₄. Accordingly, that panel will tend to rotate downwards under the force of gravity such that the device reverts to position P₀. In position P₀, L₁ (and L₃) becomes 'unlocked' and panels B and E (and panels S and C) are no longer retained in their coplanar positions. Equally, panel SCCO_MBIN_ED may be positioned on a surface and panel BECO_MBIN_ED raised to provide angle X to lock the hinge at fold line L₁. In that orientation, BE_COMBINED would rotate downwards to position P₀. The following description applies in general to the movement of the device from P₂ to P₀.

In order to prevent panel SC_COMBINED from rotating downwards into position P₀ when the device is placed on a flat surface, one or more feet 410 may be provided on the underside of panels S or C. When the device is placed on a surface, those feet will push panel SCCO_MBIN_ED upwards to an angle X, as shown in Figure 16d. Since the device is retained in the angled position P₂, panels B & E are 'locked' into the coplanar position

BEcOMBINED-

Alternative means of supporting SC_COMBINED in position P₂ are described immediately below.

As set out above, the reverse side of the hinges are recessed, typically with a V-groove. A substantially rigid stopper may be formed within the groove along the back of the hinge at fold line L₂ to prevent panels B and S from becoming coplanar. When placed on a surface in position P₂, downward movement of panel SC_COMBINED is thus prevented and SCCO_MBIN_ED is held at an angle X to the surface thus locking the hinge at fold line L₁ and retaining panels B and E in the coplanar position BECO_MBIN_ED-

If panels B, S, C and E, and the hinges at fold lines L₁, L₂, L₃ and L₄ are perfectly rigid, the stopper in hinge L₂ would prevent the device from moving into position P₀, and thus prevent movement from position P₂ to position P₁. However, in practice the hinges and panels can flex. If the stopper is configured such that angle X is small, the flex allows the device to be moved sufficiently close to position P₀ against the force of the stopper to allow the device to 'snap' from position P₂ towards P₁ and vice-versa. The stopper should not be positioned along L₄ as that would prevent the device moving between positions P₂ and P₁.

In order to reduce the force needed to move from position P₂ to P₁ and vice-versa (or if a larger angle X is required to maintain panels B & E in the coplanar position) a resilient element may be utilised in place of the rigid stopper. The element is configured to provide sufficient support to retain panel SC_COMBINED at angle X against the force of gravity, while providing a force that it is easily overcome when moving the device between positions P₂ and P₁.

The resilient element could also be located along the hinge at the fold line L₄. However, when located in that position the device must be moved against the action of the resilient element as the device is folded into position P₁. Therefore, the force provided by the resilient element must be suitably defined such that movement is possible against the resilient element and the hook 302 and catch 301 must also provide sufficient locking force to retain the device in position P₁ against the force of the resilient element.

In a further alternative a retaining part may be provided to retain the device in position P₂. The retaining part may be removable such that it can be removed to move the device from position P₂ to P₁ (through position P₀). Alternatively, the retaining part may be configured to be movable from a retaining position to a released position. The retaining part may be combined with the hook 302 described above. The retaining part may be positioned along the fold line L₄, provided it does not interfere with the folding of the device.

Figure 17a shows the underside of the device of Figure 16a-d in position P₂, and Figure 17b shows an enlarged view of a portion of the hinge at fold line L₂.

Panel S is provided with a foot protrusion 310 which protrudes into the V-groove on the reverse of the hinge at fold line L₂. A resilient element 311 is located on the panel B side of the V-groove of the hinge at fold line L₂ opposite the foot protrusion 310. The foot 310 and resilient element 31 1 are configured such that when the device is in position P₂, the resilient element 31 1 provides a force against foot 310 to retain the panel SC_COMBINED in the raised position against the force of gravity, thus locking the hinge at fold line L₁.

The resilient element and foot support the panel SC_COMBINED at the angle X as defined by the configuration of the foot and resilient element. Angle X may be defined such that it is sufficiently large to lock the hinge at fold line L₁, but small enough that panel SC_COMBINED can easily be moved against the force of the resilient element to move the device from P₂ to P₁ and vice-versa. When the device is in position P₂, the angle X may be approximately 17°.

The resilient element may be provided by any suitable means. In the embodiment shown in Figures 17a-b, deformable rubber is utilised, but other possible configurations will be apparent to the skilled person. Variation in the material characteristics of the resilient element define the force provided by the element and thus the characteristics can be altered by the selection of different materials or shapes of the element.

The device of Figures 16a-d and 17a-b may be manufactured by a two-stage moulding process. For example, the body of the device may be injection moulded in a first material, followed by a second moulding process to mould the resilient element of a second material onto the first material. The first material may be polypropylene, and the second material may be rubber.

In all of the foregoing description in relation to Figures 14 to 17a-b movement from position P₂ to position P₁ may be accomplished by applying a force to reduce angle BE. This causes the device to move through position P₀ and on to position P₁. This method of folding creates a downwards movement of panel SC_COMBINED due to flex in the panels of the device. If the panels were totally rigid panels SCCO_MBIN_ED and BECO_MBIN_ED would have to be moved directly by applying a downward force on panels SCCO_MBIN_ED- A force may then be applied to reduce the angles SB, or BE to move the device into the folded position P₁. As will be apparent, various combinations of forces and movements may be utilised to move the device between the positions in addition to those described explicitly.

The methods of supporting the device in the angled position described above are principally suitable where the angle X is less than 90°. However, it is possible that angle X is greater than 90°.

If angle X is designed to be greater than 90°, a V-groove may be provided on the upper surface of the hinge at fold line L₂₄, and a stopper or retaining device as described above may be provided to prevent movement of the panel SCCO_MBIN_ED beyond the required point. Alternatively, panel SCCO_MBIN_ED may be allowed to rotate such that X is 180° and the panel BE_COMBINED then lies directly on panel BECOMBINED-

The four panels of the device of Figures 16 and 17 are appropriately shaped and proportioned so that when in position P₁, the various edges of the four panels are aligned to create a suitable container for rinsing or draining food. To fold the device from position P₂ to position P₁, a force is applied to panels B & E as if to fold their top faces towards each other in a symmetrical manner about fold line L₁.

However, as panels BE_COMBINED are "locked" relative to each other by the inclined panel SCCO_MBIN_ED, they initially resist this applied force. As the magnitude of the folding force increases, panels BECO_MBIN_ED begin to flex upwards, causing panels SCCO_MBIN_ED to flex away from their coplanar state too and be forced downwards. This has the effect of reducing angle X.

If the panels and hinges are completely rigid it is not possible to create a downwards movement of panels SC_COMBINED by trying to fold B & E about fold line L₁. However, due to the flex in the material panels/hinges, the device can be folded in this way without being first flattened to position P₀.

As S & C rotate downwards (with some relative rotation about fold line L₃) and B & E begin to fold about L₁, the resilient element 311 is compressed by the foot 310 on panel S which leads to an increasing resistance force being applied to panel S. This continues until it reaches a point where panels C & E become coplanar (where angle CE = 180°). This will be referred to as angle X_SNAP, which is determined by the stiffness of the resilient element and the amount of flex in the hinges and panels. This is the angle at which the resilient element's force applied to panel S peaks. As angle CE increases above 180°, panel S changes its direction of travel and begins to rotate upwards about fold line L₂ which allows the resilient element to expand again, thereby reducing the force ultimately to zero as S reaches angle XC_HO_PPING, where the resilient element is in its uncompressed state.

As the force of the resilient element peaks in this way at X_SNAP, the device feels unstable at this angle which gives it a positive "snap" feeling when folding from P₂ to P₁ and vice versa.

Meanwhile, panels B & E are still rotating in the same direction towards each other under the applied force. As the device approaches position P₁, the hook 302 aligns with catch hole 301. By applying an additional force between panels S & C (or S & E), the hook 302 is forced into the catch hole 301. This secures the device in the folded position P₁.

Feet 320 are provided in the vicinity of the hinge at fold line L₁ to support the device when placed in the folded position P₁ on a surface. Feet 320 are configured such that they do not interfere with folding of the device along L₁ as described, while preventing panels B and E from being folded excessively the wrong way (i.e. where angle BE increases significantly above 180°. Additional feet may also be provided along the hinge at fold line L₃.

The external perimeter of the four combined panels B, S, C and E may be slightly tapered in cross-section and made from a rubber type material to assist with lifting any part of the device and generally make handling easier through improved grip. Further, on the underside faces of panels C & S, there are larger "grip areas" to indicate where force should be applied when mating the hook 302 with the catch hole 301 and to provide increased levels of grip whilst holding the device during rinsing or draining food. Those grip areas may be provided by a texture moulded onto the panels or may be provided by rubber, or other suitable material, areas.

To flatten the device from the folded position P₁ to the angled position P₂, the hook 302 & catch hole 301 are disengaged (as described previously) and panels B & E are opened so that the angles BE, BS and CS (measured between the panel faces) are all increasing and CE is decreasing until the foot 310 rests on the resilient element 311.

At this point, a downward force is applied to panels B & E (which are not yet coplanar) to compress the resilient element 311 until E & C become coplanar, at which point, the resilient element 31 1 forces panel S upwards which causes panels B & E and S & C to become substantially coplanar (as BECOMBINED and SCCOMBINED)- The device is thus in position P₂ and may be used for cutting or chopping items placed on the surface of panel BECOMBINED-

Catch hole 301 may also be utilised to hang the device for storage or display in shops. Furthermore, panel SCCO_MBIN_ED can be rotated to lie directly on panel BECO_MBIN_ED to reduce the size of the device for storage.

As will be appreciated by the skilled person, variations on the above embodiments are envisaged which are within the scope of the present invention.

For example, the above embodiments are made of polypropylene. However, it is possible to carry out the invention using other materials or combinations of materials. For example any stiff or rigid material (other plasties, wood, metals, etc.) could be used for the four panels and these could be combined with a flexible material such as leather or fabric to act as the fold line. Alternatively conventional hinges (e.g. metal hinges) could be bolted, glued or otherwise fixed to, for example, wooden panels. In one embodiment, the rigid panels could be in plastic (or another material) with the fold lines formed in over-moulded rubber.

While the above embodiments have been described as being moulded, the invention could instead incorporate machined, cast or pressed materials, which may be plastics, metals or the like. Alternatively, the material may be a composite material, perhaps comprising an aluminium clad plastic panel. By cutting though one of the outer aluminium layers of cladding and the plastic core, a hinge may be formed at the remaining aluminium outer layer.

In the embodiments described above, the fastener is a 'hook and catch' fastener. However, in other embodiments, the fastener could comprise one or more of, for example, a nut and bolt, a popper fastening, a tie fastening, a magnet, glue, welding or the like. Alternatively, a band could be passed around the structure. In some embodiments, no fastening will be required.

In addition, while the above described embodiments include a colander 100 and a chopping board & rinsing device, the invention is not limited to such applications. The invention could instead be used as a bowl, vessel or other sort of container. Alternatively, the invention could be inverted and used as a platform. Some purely exemplary embodiments may comprise: a fruit bowl, a laundry basket, a stool, a tent etc. It will be appreciated that, if all the hinges are formed on one side of the material (and the drainage holes removed), the vessel or the like can be made water proof and used to contain or to exclude liquids. Although in the above embodiments, the living hinges 800 are approximately 0.5mm thick, in other embodiments they could be, for example, between 0.1 mm - 2mm thick or thicker still.

While one of the embodiments described has four corner modules, other embodiments are possible. For example one embodiment may comprise two corner modules 200 and be arranged to form a four-sided container. Such a container could have drainage holes in one or more of its sections and therefore be utilised as a colander.

While embodiments of the invention having one or four (or other multiples of) corner modules have been described, other configurations are possible. The corner modules may be combined in any quantity, combination or order that allows the modules to perform their function. As will be appreciated, the modules may be mirrored about an axis to provide clockwise and counter-clockwise versions. Such versions perform identical functions, but may be combined to provide different functionality.

Hinges/fold lines of one module may also form hinges/fold lines of other modules. For example, the hinge at fold line L₁ of the device of Figures 16a-d and 17a-b may also form a hinge at fold line L₂ for a further module located at the open end of the device of Figures 16a-d and 17a-b. Some embodiments may have more than one use, for example, serving as a chopping board in its flat state and as a colander in its folded state.

Claims

1. A sheet material arranged to fold to form a corner module, the sheet comprising a face and an underside, wherein the corner module is formed by four substantially convergent fold lines defining four stiff sections in the sheet, wherein three of the fold lines are arranged to allow the sheet to fold so as to reduce the angle between the faces of adjacent sections and one of the fold lines is arranged to allow the sheet to fold so as to increase the angle between the faces of adjacent sections, and the sections comprise a base section about which the corner is formed, a side section, an end section and a corner section, the sections being arranged such that:

the base section is connected to the end section via the first fold line and to the side section by the second fold line,

the corner section is connected to the side section via the third fold line and to the end section by the fourth fold line,

wherein the fold lines are arranged such that, as the corner is formed, the angle between the face of the corner section and the face of the side section decreases, the angle between the face of the end section and the face of the corner section increases, the angle between the face of the end section and the face of the base section decreases, and the angle between the face of side section and the face of the base section decreases.

2. A sheet according to claim 1 which is arranged such that internal stresses develop during the formation of a corner so as to create a snap feel between the unfolded state and the corner state.

3. A sheet according to claim 2 which comprises at least one stress relief means to limit the internal stresses.

4. A sheet according to claim 2 or 3 in which the internal stresses are created by one or more of:

providing at least one fold line in the face of the sheet and at least one fold line on the underside of the sheet;

providing a stopper associated with a fold line which acts to prevent sections connected by that fold line assuming a coplanar relationship; providing a resilient element, wherein the resilient element is compressed as the angle between two adjacent section faces is increased.

5. A sheet according to claim 4, in which the stresses are created by a resilient element wherein the resilient element is located on a first section and is compressed by a protrusion on a second section joined to the first section by a hinge.

6. A sheet according to claim 4 in which the stresses are provided by a resilient element, wherein the resilient element is compressed as the base and the side section relatively rotate about the second fold line.

7. A sheet according to claim 5 or claim 6, wherein the resilient element is formed on the base section and is compressed by a protrusion on the side section.

8. A sheet according to any preceding claim in which at least one fold line is inset from the face or the underside of the sheet.

9. A sheet according to any preceding claim in which one or more of the fold lines is offset from a point where two or more of the fold lines converge together.

10. A sheet according to claim 3 or any claim as it depends on claim 3 in which the stress relief means comprises a hole which extends through the sheet such that the fold lines terminate at the edge of the hole.

1 1. A sheet according to claim 10 wherein the hole extends along at least one of the fold lines.

12. A sheet according to claim 1 1 wherein the hole extends along two of the fold lines.

13. A sheet according to any of claims 10 to 12 further comprising a stress relief slot through a section and terminating at the hole.

14. A sheet according to any preceding claim in which the corner section is brought into face-to-face contact with the side section such that the angle between the face of the corner section and the face of the side section is approximately zero.

15. A sheet according to any preceding claim in which the sheet is formed of a single material.

16. A sheet according to any preceding claim in which the fold lines are formed by weakened regions of the material.

17. A sheet according to any preceding claim which comprises a material with a thickness and the fold lines are formed by regions of reduced thickness.

18. A sheet according to claim 17 in which at least one fold line is formed by V- shaped grooves cut away from the face and/or the underside of the sheet.

19. A sheet according to any preceding claim which comprises a material having living hinge properties.

20. A sheet according to any preceding claim which comprises polypropylene.

21. A sheet according to any preceding claim which comprises more than one corner module.

22. A sheet according to claim 21 in which at least one of the corner modules is a mirror of at least one other corner module.

23. A sheet according to any preceding claim in which the sheet is arranged such that it is stackable with other such sheets when in the unfolded state.

24. A sheet according to claim 23 in which the sheet comprises a means of registering the sheet against another such sheet.

25. A sheet according to any preceding claim which comprises fastenings arranged to hold the corner module in its folded state.

26. A sheet according to claim 25 in which the fastenings are arranged such that they are substantially within the profile of the sheet when it is in its unfolded state.

27. A sheet according to any preceding claim having a plurality of drain holes through at least one of the sections of the sheet.

28. A sheet according to any preceding claim in which the fold lines are repeatedly foldable.

29. A sheet according to any preceding claim wherein the angle between the third and fourth fold lines is less than 90°.

30. A sheet according to any preceding claim wherein the angle between the third and fourth fold lines is less than or equal to 45°.

31. A sheet according to any preceding claim wherein the angle between the first and fourth fold lines is 90°.

32. A sheet according to any preceding claim wherein the angle between the second and fourth fold lines is 180°.

33. A sheet according to any preceding claim arranged such that, once the corner is formed, the angle between the face of the corner section and the face of the side section is less than 90 degrees.

34. A collapsible object comprising a sheet according to any preceding claim folded to form at least one corner module.

35. A collapsible object according to claim 33 wherein, when the corner is formed, the angle between adjacent sections is 90°.

36. A collapsible object according to claim 33 or 34 which comprises a colander.