SANDWICH PANEL, METHOD OF BUILDING SUCH A SANDWICH PANEL, A CORE OF SUCH A SANDWICH PANEL, AND A BUILDING BUILT OF A PLURALITY OF SUCH SANDWICH PANELS

Abstract

The invention relates to a sandwich panel, comprising: —a core, comprising: —a plurality of zigzag-shaped first spacers extending in a first longitudinal direction, each first spacer comprising at each corner thereof a first loop; —a plurality of zigzag-shaped second spacers extending in the first longitudinal direction, each second spacer comprising at each corner thereof a second loop, each second loop having outer dimensions that are smaller than the inner dimensions of each first loop, —wherein the second loops of each second spacer extend through the first loops of an adjacent first spacer; —wherein the openings defined by the second loops of successive second spacers are registered in rows extending in a second longitudinal direction, which second longitudinal direction extends under an angle of at least 20° with respect to the first longitudinal direction; and—wherein the first spacers and the second spacers define a second zigzag-shape in the second longitudinal direction; —two skin layers arranged on opposite sides of the core, wherein each skin layer comprises a plurality of openings through which the second loops extend; —a plurality of rods, each rod extending through the openings of the second loops of each row at the outer surface of each skin layer such that each rod locks the second loops in the first loops with respect to the skin layer. The invention further relates to a method of building such a sandwich panel, a core of such a sandwich panel, and a building built of a plurality of such sandwich panels.

Description

The invention relates to a sandwich panel comprising a core and two skin layers arranged on opposite sides of the core. Such a sandwich panel is known per se.

It is an object of the invention to provide a sandwich panel that allows for easy assembling of the core and the two skin layers, such that said core and said two skin layers may be transported in a disassembled state and to be easily assembled on site.

In order to accomplish that objective, the sandwich panel according to the invention comprises:

• • a core, comprising:
    • a plurality of zigzag-shaped first spacers extending in a first longitudinal direction, each first spacer comprising at each corner thereof a first loop;
    • a plurality of zigzag-shaped second spacers extending in the first longitudinal direction, each second spacer comprising at each corner thereof a second loop, each second loop having outer dimensions that are smaller than the inner dimensions of each first loop,
    • wherein the second loops of each second spacer extend through the first loops of an adjacent first spacer;
    • wherein the openings defined by the second loops of successive second spacers are registered in rows extending in a second longitudinal direction, which second longitudinal direction extends under an angle of at least 20° with respect to the first longitudinal direction; and
    • wherein the first spacers and the second spacers define a second zigzag-shape in the second longitudinal direction;
  • two skin layers arranged on opposite sides of the core, wherein each skin layer comprises a plurality of openings through which the second loops extend;
  • a plurality of rods, each rod extending through the openings of the second loops of each row at the outer surface of each skin layer such that each rod locks the second loops in the first loops with respect to the skin layer.

The sandwich panel according to the invention allows for easy assembling by arranging the skin layers on opposite sides of the core and by then placing the rods through the rows of second loops.

The sandwich panel according to the invention may be used as, but not limited to, a wall or a roof of a construction or (emergency) building, such as a house, an office building, a garage, a storage shed, a stadium, a stable, a quay, a dam, a sewer drain, a swimming pool, etc, or as a bower, a sound wall, a (decorative or protective) (garden) fence, a grandstand, a presentation wall, a display, a bike park, a stage, as a building toy optionally for educational purposes, or as part of a bridge (head), of a viaduct, of the casco of a house-boat, etc.

The core may for example be manufactured from a material from the group comprising metal, such as iron or (stainless) steel, and (fibre reinforced) plastic or composite material.

Practically the angle is approximately 90°.

In an embodiment of the sandwich panel according to the invention, said sandwich panel comprises limitation means for limiting the distance by which each second loop extends through each first loop and/or by which each second loop extends through each opening in each skin layer.

The second spacer and/or the first spacer may comprise said limitation means, said limitation means comprising two elongated elements extending in the first longitudinal direction, which elongated elements mutually connect the second loops on each longitudinal side of the second spacer and/or which elongated elements mutually connect the first loops on each longitudinal side of the first spacer.

The elongated elements have the further advantage of clearly defining the location of the first loops and the second loops in the first longitudinal direction, such that the location of the openings of the skin layers may be easily be adapted thereto.

Practically the angle of the first loop with respect to the longitudinal plane of the first spacer lies in the range of between 90° to 150°.

An angle of approximately 90° has the advantage that the core of the sandwich panel is foldable to a folded up first state in which the core has a more or less flat shape, such that the core requires relative small space, which is convenient for, for example, transport and storage. At a building site the core is easily expandable to its expanded state, in which the core functions as a spacer for the sandwich panel.

When the size of the openings of the skin layers is smaller than the size of the first loops, such that the first loops cannot extend through the openings of the skin layers, this angle of the first loop with respect to the longitudinal plane of the first spacer limits the maximum angle of the longitudinal plane of the first spacer with respect to the skin layers, which maximum angle is obtained when the first loops extend parallel to the skin layers. By choosing an appropriate angle of the first loop with respect to the longitudinal plane of the first spacer, the maximum angle of the longitudinal plane of the first spacer with respect to the skin layers is defined as 180° minus the angle of the first loop with respect to the longitudinal plane of the first spacer. Thus the maximum angle is approximately 60°, respectively approximately 45°, if the angle of the first loop with respect to the longitudinal plane of the first spacer is approximately 120°, respectively approximately 135°.

The angle of the first loop with respect to the skin layer may lye in the range of between 0° to 45°.

An angle of the second loop with respect to the longitudinal plane of the second spacer may lye in the range of between 120° to 180°.

The angle of the second loop with respect to the skin layer is preferably approximately 90°, such that the rods may easily be placed through the openings of the second loops.

With the angle of the second loop with respect to the skin layer being preferably approximately 90° and the angle of the second loop with respect to the longitudinal plane of the first spacer being in the range of between 120° to 180°, an angle between the longitudinal plane of the second spacer and the skin layers is between 120° to 180° minus approximately 90°, i.e. between 30° to 90°.

Preferably, the angle of the longitudinal plane of the first spacer and/or the angle of the longitudinal plane of the second spacer with respect to the skin layers lies in the range of between 30° to 90°. These angles may be equal or different for the first spacers and the second spacers.

All angles may be chosen in accordance with required strength of the sandwich panel, and in accordance with desired dimensions of the sandwich panel.

In an embodiment of the sandwich panel according to the invention, at least one of the two skin layers is a mesh.

Such a mesh has the advantage that it comprises more openings than the core comprises second loops, such that the second loops may easily be placed through the openings of the mesh. Also, such a mesh is relatively cheap.

The mesh may for example be made from a material from the group comprising metal, such as iron or (stainless) steel and (fibre reinforced) plastic or composite material.

A sandwich panel comprising such mesh skin layers may for example be filled with rocks and mud and may for example be used as a noise protection wall that may for example be located along roads in urban areas.

Also, such a sandwich panel may conveniently be used for building houses and other buildings, such as stores and offices, in area's that have suffered from a natural disaster, such as an earth quake. The broken bricks and other remainings of collapsed buildings may be used as a filling material for filling up the core of the sandwich panel, such that new buildings may be made relatively easy and fast. Thus, the people living in said area may have new homes relatively fast. Such homes may be temporally, wherein more permanent buildings may be built while the people are living in homes comprising the sandwich panels according to the invention. After finishing the more permanent buildings, said temporally homes and buildings may easily be disassembled by removing first the rods, then the skin layers, and by then folding up or dismounting the core. The sandwich panels may then be reused used at a different location. For such an application, it is convenient if the core, skin layers and rods are transported to the natural disaster area in a disassembled state and being assembled on site. Said core is preferable transported in its folded up state.

After filling the panel with mesh skin layers, for example with rubble, luting with concrete may take place. This way, a relatively cheap and low-weight water tight construction element may be formed, which can be used for any of the above described purposes. Alternatively or additionally, at least one of the two skin layers may be a panel.

Such a panel has the advantage, that the core and/or the optional filling of the core of the sandwich panel, is at least less visible from the outside. The thickness of the panel may be chosen as desired.

The panel may for example be made from a material from the group comprising wood, metal, such as iron or (stainless) steel and (fibre reinforced) plastic or composite material.

Alternatively or additionally, at least one of the two skin layers may be a sandwich panel, comprising a core and two skin layers, wherein the core and an inner skin layer of the two skin layers comprise said plurality of openings and wherein the outer skin layer covers said plurality of openings.

Such a sandwich panel skin layer has the advantage, that the outer skin layer covers said plurality of openings and the second loops and rods located therein. Thus, the openings, second loops and rods are not visible from the outside. The outer skin layers may for example comprise a finishing layer, such as finish plaster, wood, tiles, bricks or the like, such that after assembly of the sandwich panel 1000 no further finishing is required. One of the finishing layers of the outer skin layers may for example be watertight, such that the sandwich panel may be used as an outer wall of a building, also in areas where rain occurs. The core may for example be made of a noise or energy isolating layer, such as polyurethane (PUR).

Since the loops are not visible from the outside, practically said sandwich panel comprises guiding means provided in the core of said sandwich panel skin layer for guiding the rods through said second loops.

Said guiding means may for example comprise guiding pipes or tubes.

The sandwich panels comprising panels as skin layers or sandwich panels as skin layers may also be used for building buildings, such as houses, stores and offices. For example as temporary buildings in areas that have suffered from a natural disaster, as well as more permanent buildings in all areas.

The invention also relates to a method of building a sandwich panel according to any of the preceding claims, comprising the steps of:

a) building a core, comprising the steps of:

• • providing a plurality of zigzag-shaped first spacers extending in a first longitudinal direction, each first spacer comprising at each corner thereof a first loop;
  • providing a plurality of zigzag-shaped second spacers extending in the first longitudinal direction, each second spacer comprising at each corner thereof a second loop, each second loop having outer dimensions that are smaller than the inner dimensions of each first loop,
  • placing the second loops of each second spacer through the first loops of an adjacent first spacer, wherein the openings defined by the second loops of successive second spacers are registered in rows extending in a second longitudinal direction, which second longitudinal direction extends under an angle of at least 20° with respect to the first longitudinal direction, and wherein the first spacers and the second spacers define a second zigzag-shape in the second longitudinal direction; and

b) arranging two skin layers on opposite sides of the core by placing the second loops of the core through openings of the skin layers;

c) placing a plurality of rods through the openings of the second loops of each row at the outer surface of each skin layer such that each rod locks the second loops in the first loops with respect to the skin layer.

With such a method the sandwich panel may be built relatively easy and fast. Also, the sandwich panel may easily and/or fast be dismantled by reversing the steps.

The invention further relates to a core of a sandwich panel, said core comprising:

• • a plurality of zigzag-shaped first spacers extending in a first longitudinal direction, each first spacer comprising at each corner thereof a first loop;
  • a plurality of zigzag-shaped second spacers extending in the first longitudinal direction, each second spacer comprising at each corner thereof a second loop, each second loop having outer dimensions that are smaller than the inner dimensions of each first loop,
  • wherein the second loops of each second spacer extend through the first loops of an adjacent first spacer;
  • wherein the openings defined by the second loops of successive second spacers are registered in rows extending in a second longitudinal direction, which second longitudinal direction extends under an angle of at least 20° with respect to the first longitudinal direction; and
  • wherein the first spacers and the second spacers define a second zigzag-shape in the second longitudinal direction.

The core may further comprise the features as described with respect to the sandwich panel that relate to said core.

Preferably, the core is foldable between a folded up first state and an expanded second state.

In the folded up first state the core requires less space than in the expanded second state, such that the core may easily be transported and stored in the folded up first state. At a building the core may easily be expanded to its expanded state. Dependent on the angle of the first loop with respect to the longitudinal plane of the first spacer, the core may have a more or less flat shape in the folded up state.

The invention also relates to buildings built using a plurality of sandwich panels according to the invention. Such buildings may be built relatively easy and fast and may conveniently be used in any area, in particular in areas that have suffered from a natural disaster. Means for mutually connecting a plurality of the sandwich panels may be provided. The sandwich panels may be used as walls, roofs, floors, or any desired part of the building.

The invention will now be explained in more detail with reference to figures illustrated in a drawing, wherein:

FIG. 1 shows a part of a sandwich panel according to a first embodiment of the invention;

FIG. 2 shows the sandwich panel of FIG. 1 in an exploded view;

FIG. 3 shows a detailed view of the core of the sandwich panel of FIG. 1;

FIGS. 4A and 4B show a first spacer (A) and a second spacer (B) of the core of the sandwich panel of FIG. 1;

FIG. 5 is a side view of a first assembling method of the sandwich panel of FIG. 1;

FIG. 6 shows a sandwich panel according to a second embodiment of the invention;

FIG. 7 shows the sandwich panel of FIG. 6 in an exploded view;

FIGS. 8A and 8B show a sandwich panel according to a third embodiment of the invention;

FIGS. 9A and 9B show a first spacer (A) and a second spacer (B) according to a second embodiment of the spacer according to the invention;

FIGS. 10A-10C are a side view of a second assembling method of the core of the sandwich panel of FIG. 1; and

FIGS. 11A-11C are a side view of the second assembling method of a core according to a further embodiment of the invention;

FIGS. 12A, 12B show cores according to a further embodiment of the invention in the expanded second state of FIGS. 10C and 11C, respectively.

FIGS. 1, 2 and 3 show a sandwich panel 1 according to a first embodiment of the invention, which sandwich panel comprises a core 2, two skin layers 3A, 3B, a plurality of rods 4, and four side panels 5A-5D.

The core 2 comprises a plurality of zigzag-shaped first spacers 6, which first spacers 6 extend in a first longitudinal direction 8. Each first spacer 6 comprises at each corner thereof a first loop 9. The first loops extend parallel with respect to the skin layers 3A, 3B and under an angle 25 of approximately 120° with respect to a longitudinal plane of the first spacer 6 (see FIG. 5).

The core 2 further comprises a plurality of zigzag-shaped second spacers 7, which also extend in the first longitudinal direction 8. Each second spacer 7 comprises at each corner thereof a second loop 10, wherein the outer dimensions of the second loops 10 are smaller than the inner dimensions of each first loop 9, such that the second loops 10 may extend through the first loops 9. The second loops 10 extend perpendicular with respect to the skin layers 3A, 3B and under an angle 26 of approximately 150° with respect to a longitudinal plane of the second spacer 7, see FIG. 5.

At the side zones of the core 2, said core 2 comprises a second type of second spacer 19, as is seen in FIGS. 1 and 3. This second type of second spacer 19 differs from the first type second spacer 7 only in that the second loops 20 extend in the same direction as the longitudinal plane of the second type second spacer 19, such that the second type second spacer 19 extends perpendicular with respect to said skin layers 3A,3B. Thus, the angle 26 of the second type second spacer is 180°, instead of 150°.

As is clear from FIG. 3, the second loops 10 of each second spacer 7 extend through the first loops 9 of an adjacent first spacer 6, such that the first spacers 6 and the second spacers 7 define a second zigzag-shape in a second longitudinal direction 11, which second longitudinal direction 11 extends under an angle of 90° with respect to the first longitudinal direction 8. In FIG. 3, the first longitudinal direction 8 of the zigzag-shapes of the first spacers 6 and the second spacers 7,19 is elucidated by the black colour of the second type second spacer 19. The second longitudinal direction 11 of the zigzag-shape defined by the coupled first spacers 6 and second spacers 7 is elucidated by the dashed upper bars of the first and second spacers 6,7,19.

As is further clear from FIG. 3, only at one side of the second type second spacer 19 do the second loops 20 extend through the first loops 9 of the first spacer 6. At the other side of the second type second spacer 19 the second loops 20 extend only through the openings 13 of skin layer, see FIG. 1. This is the result of the second type second spacer 19 being the outer second spacer.

As is further clear from FIG. 3, the openings 12 defined by the second loops 10, 20 of successive second spacers 7,19 are registered in rows extending in the second longitudinal direction 11, such that the rods 4 can be placed through the second loops 10, 20.

The skin layers 3A, 3B are arranged on opposite sides of the core 2, wherein each skin layer 3A, 3B is a mesh comprising a plurality of openings 13 through which the second loops 10,20 extend.

As is clear from FIG. 1, the rods 4 extend through the openings 12 of the second loops 10,20 of each row at the outer surface of each skin layer 3A, 3B such that each rod 4 locks the second loops 10,20 in the first loops 9 with respect to the skin layer 3A, 3B.

The side panels 5A-5D are also a mesh comprising openings 14. Each mesh 5A-5D comprises edge zones 15 extending under an angle of 90° with respect of a main plane of the panels 5A-5D, such that the edge zones 15 extend parallel with respect tot the skin layers 3A, 3B. The second loops 10,20 that are located at the outer zones of the core 2 extend through the openings 14 of the edge zones 15 of the panels 5A-5D and the rods 4 extend through the openings 12 of the second loops 10,20 at the outer surface of the edge zones 15 of the panels 5A-5D, such that each rod 4 locks the second loops 10,20 in the first loops 9 with respect to the skin layer 3A, 3B and the side panels 5A-5D.

As is clear from FIG. 3, each spacer 6,7 comprises two elongated elements 16,17 extending in the first longitudinal direction 8. The elongated elements 16,17 are fixedly mounted to the corners of each spacer 6,7 at each longitudinal side of the spacers 6,7, and thus at the locations from which the loops 9,10 extend. As such, the elongated elements 16,17 mutually connect the loops 9,10 at each side of the spacers 6,7. As a result of the elongated elements 16,17 the locations of the loops 9,10 with respect to the first longitudinal direction 8 are clearly defined, such that the locations of the openings of the skin layers 3A, 3B and the side panels 5A-5D may easily be adapted thereto. This is especially important if the skin layer is a skin layer according to FIGS. 6-8, as will be explained later. The elongated elements 17 of the second spacer 7 limit the distance by which each second loop 10 extends through each first loop 9 and the elongated elements 16 of the first spacer 6 limit the distance by which each second loop 10 extends through each opening 13 in each skin layer 3A,3B by preventing the first loops 9 from extending through the openings 13. The second type second spacer 19 comprises elongate elements 28, also extending in the first longitudinal direction 8, which elongated elements 28 mutually connect the loops 20 at each longitudinal side of the second type second spacer 19.

FIG. 4A shows a perspective view of the first spacer 6. This figure clearly shows the elongated elements 16 extending in the first longitudinal direction 8 and connecting the loops 9. FIG. 4A further shows the angle 21 of the zigzag-shape, which is approximately 60°. The angle 22 of the outer zigzag is half the angle 21, which is thus approximately 30°. The outer zigzag thus extends in a plane that is perpendicular to the skin layers 3A,3B.

FIG. 4B shows a perspective view of the second spacer 7. This figure clearly shows the elongated elements 17 extending in the first longitudinal direction 8 and connecting the loops 10. FIG. 4B further shows the angle 23 of the zigzag-shape, which is approximately 60°. The angle 24 of the outer zigzag is half the angle 23, which is thus approximately 30°. The outer zigzag thus extends in a plane that is perpendicular to the skin layers 3A,3B.

FIG. 5 shows in detail how the sandwich panel is assembled. Each second spacer 7 is coupled to a first spacer 6 and the skin layer 3A, by placing the second loop 10 in the first loop 9 and in the opening 13 of the skin layer 3A. Once the second loop 10 extends through the first loop 9 and the opening 13 of the skin layer 3A, a rod 4 is placed through the registered openings 12 of the second loops 10 at the outer surface of the skin layer 3A, such that the rod 4 locks the second loops 10 in the first loops 9 with respect to the skin layer 3A, 3B.

As described above, FIG. 5 shows the angles 25, 26 of the loops 9,10 with respect to the longitudinal planes of the spacers 6,7, which angles 25,26 are respectively 120° and 150°. An angle 27 of the longitudinal planes of the spacers 6,7 with respect to the skin layers 3A, 3B is 60°, such that also the angle 29 between the longitudinal planes of the spacers 6,7 is 60°. Dependent on the required strength of the sandwich panel 1 and the desired distance between the skin layers 3A,3B, the angles 25,26,27 may be chosen differently.

The second type second spacer 19 is not disclosed in FIG. 5. As described above, the angle 26 of the second type second spacer 19 is 180° and the loops 20 extend perpendicular with respect to the skin layers 3A,3B, such that the angle 27 of the longitudinal plane of the second type second spacer 19 with respect to the skin layers 3A, 3B is 90°.

FIGS. 6, 7 show a second embodiment of a sandwich panel 100. The core 2 of the sandwich panel 100 is the same core 2 of the sandwich panel of FIGS. 1-5 and is described above, wherein the same numbers refer to the same above described features. The skin layers 103A,103B differ from the skin layers 3A,3B of FIG. 1,2 in that the skin layers 103A,103B are not meshes, but panels comprising openings 113. The number and location of the openings 113 of the skin layers 103A,103B are adapted to the number and location of the second loops 10,20 of the core 2. As described above, as a result of the elongated elements 16,17,28 the locations of the loops 9,10,20 in the first longitudinal direction 8 are clearly defined, such that the locations of the openings 113 of the skin layers 103A, 103B may easily be adapted thereto. This is important because the skin layers 103A,103B have openings 113 only at the location of the second loops 10,20, and thus the same number of openings 113 as the number of second loops 10,20, which is different to the mesh skin layers 3A,3B, which comprise much more openings 113 than the core 2 comprises second loops 10,20.

As is clear from FIGS. 6, 7, the first longitudinal direction 8 now extends horizontal and the second longitudinal 11 now extends vertical, which is opposite to FIGS. 1-5, in which FIGS. 1-5 the first longitudinal direction 8 extends vertical and the second longitudinal direction 11 extends horizontal. It is therefore clear for the skilled person that the orientation of the core 2 is unimportant. For practical reasons the orientation of the core 2 of FIGS. 6,7 may be chosen when the height of the sandwich panel 100 is relatively low, such that the rods 4 may easily be placed from above through the registered openings 12 of the loops 10,20 of the second spacers 7,19.

FIGS. 8A and 8B show a second embodiment of a sandwich panel 1000. The core 2 of the sandwich panel 1000 is the same core 2 of the sandwich panel of FIGS. 1-5 and is described above, wherein the same numbers refer to the same above described features. The skin layers 1003A,1003B differ from the skin layers 3A,3B of FIG. 1,2 and the skin layers 103A,103B of FIGS. 6,7 in that the skin layers 103A,103B are sandwich panels. The sandwich panels 1003A,1003B comprise openings 1013 that extend only through the inner skin layers 1030, which inner skin layers 1030 are directed to the core 2 of the sandwich panel 1000, and the core 1031 of the sandwich panels 1003A,1003B. The outer skin layers 1032 cover the openings 1013, such that the openings 1013, the loops 10,20 and the rods 4 are not visible from the outside. The outer skin layers 1032 may for example comprise a finishing layer, such as finish plaster, wood, tiles, bricks or the like, such that after assembly of the sandwich panel 1000 no further finishing is required. One of the finishing layers of the outer skin layers 1032 may for example be watertight, such that the sandwich panel 1000 may be used as an outer wall of a building. The core 1031 may for example be made of a noise or energy isolating layer, such as polyurethane (PUR).

As is seen in FIG. 8B, pipes 1033 extend in rows in the second longitudinal direction 11 through the core 1031 of the sandwich panels 1003A,1003B over the total length of the sandwich panels 1003A,1003B. The pipes 1033 extend from each opening 1013 to a next opening 1013, but not through the opening 1013, such that the second loops 10,20 can be placed in the openings 1013. The pipes 1033 serve as guiding means for the rods 4, wherein the rods 4 may be placed in the pipes 1033 from the outer end zones of the sandwich panels 1003A,1003B. Such guiding means 1033 are convenient, because, as described above, the loops 10,20 are not visible from the outside due to the presence of the outer skin layers 1032 and thus enhance the placing of the rods 4 through the second loops 10,20.

FIGS. 9A and 9B show second embodiments of the first and second spacers 106,107 comprising respective first loops 109 and second loops 110. The first and second spacers 106,107 of FIGS. 9A, 9B differ from the first and second spacers 6,7 of FIGS. 4A, 4B only in that the first and second spacers 106,107 do not comprise said elongated elements. Such first and second spacers 106,107 may be applied if the location of the openings of the skin layers of the sandwich panel is not critical, for example when the skin layers are the meshes of FIGS. 1,2 and/or when the skin layer itself provides sufficient strength and stability.

FIGS. 10A-10C are a side view of a second assembling method of the core 2 of the sandwich panels 1,100,1000 of FIGS. 1-8. From these FIGS. 10A-10C it is clear that the core 2 is foldable between a folded up first state (FIG. 10A) and an expanded second state (FIG. 10C). FIG. 10B shows an intermediate state. In the folded up first state the core 2 requires less space as compared to the expanded second state, which is convenient for transport and storage of the core 2. At a building site the core 2 may be folded from the first state to its expanded second state and then coupled to the skin layers 3A,3B,103A,103B,1003A,1003B by placing the rods 4 through the second loops 10,20. The first and second spacers 6,7,19 stay mutually connected during the folding of the core 2 by means of said loops 9,10,20, such that folding between the first and second states may take place relatively easy and fast.

FIGS. 11A-11C are a side view of the second assembling method of a further core 102 according to the invention. The core 102 differs from the core 2 of FIGS. 1-8 in that the angle 125 between the loop 109 of the first spacer 106 and the longitudinal plane of the first spacer 106 is 90° instead of 120°. As a result of the angle 125 being 90°, the longitudinal planes of the first and second spacers 106,107 extend parallel in the folded up first state of FIG. 11A. As such, the core 102 has a more or less flat shape in the folded up state and thus requires much less space in the folded up first state as compared to the expanded second state of the core 102 as shown in FIG. 11C. FIG. 11B shows an intermediate state. It is noted that the second spacer 107 of the core 102 is equal to the second spacer 7 of the core 2 of FIGS. 1-8. The second type second spacer 19 is not disclosed in FIGS. 11A-11C and is also equal to the second type second spacer of the core 2 of FIGS. 1-8. As described above with respect to FIGS. 10A-10C, the first and second spacers 106,107,19 stay mutually connected during the folding of the core 2 by means of said loops 109,110,20, such that folding between the first and second states may take place relatively easy and fast.

In order to prevent the first spacers 6;106 and the second spacers 7,19;107,19 from uncoupling during folding, coupling means in the form of a wires, tapes or belts may be provided that connect each first loop 9;109 of a first spacer 6;106 to a second loop 10,20;110,20 of an adjacent second spacers 7,19;107,19 together and as such prevent uncoupling. The wires, tapes or belts may also be provided around each pair of elongated elements 16,17,28 of each pair of adjacent first spacers 6;106 and second spacers 7,19;107,19.

As is clear from FIG. 11C, as a result of the angle 125 being 90°, the first loop 109 does not extend parallel to the skin layer of the sandwich panel.

FIGS. 12A; 12B show cores 2; 102 in the expanded state of FIGS. 10C; 12C, respectively, which cores 2; 102 differ from the cores of FIGS. 10A-10C; 11A-11C in that the first spacers 6; 106 comprise an abutment 40; 140, which abutments 40; 140 limit the maximum angle between the longitudinal planes of the first and second spacers 6,7; 106,107 in the expanded second state. The maximum angle between the longitudinal planes of the first and second spacers 6,7; 106,107 in the expanded second state is preferably 60°, see also FIG. 5 in which this angle is denoted by reference numeral 29. The abutments 40; 140 are formed by bended portions of the first loops 9; 109 on both sides of the first spacers 6; 106.

The invention is not restricted to the variants shown in the drawing, but it also extends to other preferred embodiments that fall within the scope of the appended claims.

In this respect it is noted that all disclosed angles may be chosen as desired and in dependence of required strength and size of the sandwich panel. In particular the angle 27 between the longitudinal planes of the first and second spacers 6;106,7;107 and the skin layers 3A;103A;1003A,3B;103B;1003B may be variable and may be fixated by placing the second loops 10;110 through an opening of the skin layers 3A;103A;1003A,3B;103B;1003B and by then placing the rod through the second loops 10;110.

Claims

1. A sandwich panel, comprising:

a core, comprising: a plurality of zigzag-shaped first spacers extending in a first longitudinal direction, each first spacer comprising at each corner thereof a first loop; a plurality of zigzag-shaped second spacers extending in the first longitudinal direction, each second spacer comprising at each corner thereof a second loop, each second loop having outer dimensions that are smaller than the inner dimensions of each first loop, wherein the second loops of each second spacer extend through the first loops of an adjacent first spacer; wherein the openings defined by the second loops of successive second spacers are registered in rows extending in a second longitudinal direction, which second longitudinal direction extends under an angle of at least 20° with respect to the first longitudinal direction; and wherein the first spacers and the second spacers define a second zigzag-shape in the second longitudinal direction;

two skin layers arranged on opposite sides of the core, wherein each skin layer comprises a plurality of openings through which the second loops extend;

a plurality of rods, each rod extending through the openings of the second loops of each row at the outer surface of each skin layer such that each rod locks the second loops in the first loops with respect to the skin layer.

2. The sandwich panel according to claim 1, wherein the angle is approximately 90°.

3. The sandwich panel according to claim 1, comprising a limiter configured for limiting the distance by which each second loop extends through each first loop and/or by which each second loop extends through each opening in each skin layer.

4. The sandwich panel according to claim 3, wherein the second spacer and/or the first spacer comprise(s) said limiter, said limiter comprising two elongated elements extending in the first longitudinal direction, which elongated elements mutually connect the second loops on each longitudinal side of the second spacer and/or which elongated elements mutually connect the first loops on each longitudinal side of the first spacer.

5. The sandwich panel according to claim 1, wherein an angle of the first loop with respect to the longitudinal plane of the first spacer lies in the range of between 90° to 150°.

6. The sandwich panel according to claim 1, wherein an angle of the first loop with respect to the skin layer lies in the range of between 0° to 45°

7. The sandwich panel according to claim 1, wherein an angle of the second loop with respect to the longitudinal plane of the second spacer lies in the range of between 120° to 180°.

8. The sandwich panel according to claim 1, wherein an angle of the longitudinal plane of the first spacer and/or an angle of the longitudinal plane of the second spacer with respect to the skin layers lies in the range of between 30° to 90°.

9. The sandwich panel according to claim 1, wherein at least one of the two skin layers is a mesh.

10. The sandwich panel according to claim 1, wherein at least one of the two skin layers is a panel.

11. The sandwich panel according to claim 1, wherein at least one of the two skin layers is a sandwich panel, comprising a core and two skin layers, wherein the core and an inner skin layer of the two skin layers comprise said plurality of openings and wherein the outer skin layer covers said plurality of openings.

12. The sandwich panel according to claim 11, comprising guiding means provided in the core of said sandwich panel skin layer for guiding the rods through said second loops.

13. A method of building a sandwich panel, the method comprising:

a) building a core, comprising the steps of: providing a plurality of zigzag-shaped first spacers extending in a first longitudinal direction, each first spacer comprising at each corner thereof a first loop; providing a plurality of zigzag-shaped second spacers extending in the first longitudinal direction, each second spacer comprising at each corner thereof a second loop, each second loop having outer dimensions that are smaller than the inner dimensions of each first loop, placing the second loops of each second spacer through the first loops of an adjacent first spacer, wherein the openings defined by the second loops of successive second spacers are registered in rows extending in a second longitudinal direction, which second longitudinal direction extends under an angle of at least 20° with respect to the first longitudinal direction, and wherein the first spacers and the second spacers define a second zigzag-shape in the second longitudinal direction; and

b) arranging two skin layers on opposite sides of the core by placing the second loops of the core through openings of the skin layers;

c) placing a plurality of rods through the openings of the second loops of each row at the outer surface of each skin layer such that each rod locks the second loops in the first loops with respect to the skin layer.

14. An element, said element comprising:

a plurality of zigzag-shaped first spacers extending in a first longitudinal direction, each first spacer comprising at each corner thereof a first loop;

a plurality of zigzag-shaped second spacers extending in the first longitudinal direction, each second spacer comprising at each corner thereof a second loop, each second loop having outer dimensions that are smaller than the inner dimensions of each first loop,

wherein the second loops of each second spacer extend through the first loops of an adjacent first spacer;

wherein the openings defined by the second loops of successive second spacers are registered in rows extending in a second longitudinal direction, which second longitudinal direction extends under an angle of at least 20° with respect to the first longitudinal direction; and

wherein the first spacers and the second spacers define a second zigzag-shape in the second longitudinal direction.

15. The element according to claim 12, wherein the element is foldable between a folded up first state and an expanded second state.