EP0839088A1

EP0839088A1 - Folded-sheet honeycomb structure

Info

Publication number: EP0839088A1
Application number: EP96927019A
Authority: EP
Inventors: Jochen Pflug
Original assignee: Katholieke Universiteit Leuven
Current assignee: Katholieke Universiteit Leuven
Priority date: 1995-07-18
Filing date: 1996-07-16
Publication date: 1998-05-06
Anticipated expiration: 2016-07-16
Also published as: ATE186497T1; HUP9802572A2; JPH11509488A; NO980197D0; AU6699996A; PL324520A1; CZ12698A3; EP0839088B1; HUP9802572A3; JP4335977B2; US6183836B1; CA2227176A1; WO1997003816A1; NO980197L; CN1191508A

Abstract

Disclosed is a folded-sheet honeycomb structure for use, in particular, as the core of lightweight-construction sandwich materials, the honeycomb structure having rectangular or hexagonal walls (22) disposed at right angles to the facing layers and produced from a metal, plastic, woven-fabric, fibre-reinforced composite or paper sheet by making cuts and folding to give a rectangular waveform. This folded-sheet honeycomb structure has larger areas (13, 16) available to join it to the facing layers.

Description

Folded honeycomb

The invention relates to folded honeycombs made of a plurality of cells, to processes for producing the folded honeycombs and to applications of such folded honeycombs.

Sandwich core layers are usually made from honeycombs, the cells of which each form equilateral hexagons. The honeycomb layer is provided with cover layers that are glued to the edges of the honeycomb webs. In practice, the honeycombs are obtained by cutting off a honeycomb block. In the sandwich composite, the connection of the honeycomb edges to the cover layers is critical, which is why relatively thick adhesive layers are used to embed the honeycomb edges and the viscosity of the adhesive is closely monitored.

Honeycombs with cover layer parts integral to the cell walls are also known (US Pat. No. 4,197,341). However, such honeycombs have to be produced from individual strips, two strips of which are joined together to form a cell row, which requires precise production of the cell row elements.

It is also already known to produce folded honeycombs from a cohesive, flat body provided with cuts (WO-94/02311 = PCT / US93 / 06872). One embodiment of the folded honeycomb is provided with connection surfaces for cover layers, which, however, extend over cell wall gaps between large, octagonal cells and smaller, hexagonal cells. The other embodiment comprises hexagonal cells uniformly, but no pads for cover layers.

The invention has for its object to provide a folded honeycomb with cells of the same type, which is folded from a coherent, flat body and which offers sufficiently large connection surfaces to cover layers. The invention is defined in the claims.

ORIGINAL DOCUMENTS Externally, the new folded honeycomb differs from the folded honeycomb cut from the block in that there are connecting surfaces for cover layers running transversely to the honeycomb walls. Accordingly, if the folded honeycomb is used as a sandwich core layer, a high drum peel strength of the cover layer compared to the sandwich core layer can be achieved.

Since the folded honeycomb has differently oriented, vertical walls (i.e. walls standing transversely to one another), it is relatively shear-resistant and shear-resistant in any direction parallel to the layer.

The connection surfaces can also be designed as bridging parts which connect the cell walls in one piece and thus provide additional stiffening of the folding honeycomb transversely to the cell walls.

The bridging parts are delimited in the flat body by cuts and, if necessary, by fold lines. It is possible to make U-shaped cuts and to use all or part of the flaps thus formed as connecting surfaces.

It is also possible to produce wedge-shaped folded honeycombs or generally with a height profile. The strip-shaped parts are continuously made wider or narrower, and the boundary cuts of the strip-shaped regions are curved or made along path curves.

Before the contacting crests and sinks of the half-honeycomb shafts are permanently connected to one another, it is possible to shift or distort the folded honeycomb in order to adapt to curved surfaces, if necessary. This shape is then frozen to a certain extent by the permanent connection of the shaft crests and shaft sinks. In this way, shell-like folded honeycombs can be produced that have a certain self-carrying capacity. Folded honeycombs of this type can be processed further to form sandwich structure molded parts; the honeycomb can also be used in crash Structures.

To produce the folded honeycomb, the flat body is provided with cuts and folded, which can be carried out by a rolling process. Inexpensive production is therefore to be expected. With ordinary paper or cardboard as the starting material, a folding honeycomb is therefore considered for use as packaging material.

Exemplary embodiments of the invention are described with reference to the drawing. It shows:

1 is a flat body with fold lines and U-shaped cuts,

Fig. 2 a square wave,

Fig. 3 the square wave with a pattern,

Fig. 4 shows a folded honeycomb in perspective,

Fig. 5 a rectangular cross-folded honeycomb,

Fig. 6 another flat body with fold lines and U-shaped incisions,

Fig. 7 shows a folding honeycomb in perspective, obtainable from the flat body of FIG. 6,

Fig. 8 shows a schematic illustration of a rectangular folding honeycomb,

Fig. 9 after expansion as well

Fig. 10 after contraction of the honeycomb according to Fig. 8, further

Fig. 11 with web folding;

Fig. 12 a pulse-shaped square wave,

Fig. 13 the pulse-shaped square wave with a pattern,

Fig. 14 a rectangular cross folding honeycomb, in perspective

Representation, produced according to FIGS. 12, 13,

Fig. 15 another flat body with fold lines and

Incisions,

Fig. 16 a first folding of the flat body according to FIG.

15,

Fig. 17 another fold of the body,

Fig. 18 is a perspective view of a detail,

Fig. 19 a folding honeycomb, obtainable from the body of FIG.

15; 20 shows another flat body with fold lines and Cutouts, FIG. 21 shows an intermediate state during manufacture, FIG. 22 shows a hexagonal folded honeycomb, manufactured according to FIGS. 20, 21; 23 shows another flat body with fold lines and

Notches, Fig. 24 is an enlarged portion of a folding honeycomb made from the material of Fig. 23; 25 shows a modified folded honeycomb in an enlarged perspective view; 26 is an enlarged perspective view of a further folded honeycomb made of modified material; 27 shows a blank for wedge-shaped honeycombs, FIG. 28 shows an enlarged perspective illustration of a

Folded honeycomb made of the material of Fig. 27; 29 shows a blank for curved honeycombs, FIG. 30 shows a perspective view of a curved honeycomb

Folded honeycomb, made from the material of FIG. 29, FIG. 31, another flat body with fold lines and

Incisions, Fig. 32 an intermediate state in the manufacture, Fig. 33 a hexagonal folded honeycomb, manufactured according to Fig. 31, 32.

Fig. 1 shows a flat sheet of thin sheet metal, plastic, fabric, fiber composite material (with carbon, aramid or glass fibers) or fiber-reinforced paper (Nomex ^® paper), which forms a sandwich core layer according to the invention after folding. For purposes of explanation, the fold points are drawn in dashed lines in the web, which are folded in the course of processing. Continuous, horizontal fold lines 1, 2, 3, 4 as well as interrupted, vertical fold lines 5 and further fold lines 7, 8 are indicated in detail. To prepare for processing, strips of adhesive or soldering material 19 can be aligned with the fold lines 5 on both sides of the web be attached. The folds can also be prepared using embossing lines. One can also see rows of U-shaped cuts 9, the legs 11, 12 of which coincide with the horizontal fold lines 4, 1 and 2, 3, respectively, while the base 10 of the U extends parallel to the fold lines 5, 7. These U-cuts 9 can be produced before, during or after the folding around the folding lines 1, 2, 3, 4, punching being preferred. The U-cuts 9 delimit layer lobes, which are to be bent from the plane of the web into the sandwich core layer to be formed. As can be seen, the ends of the legs 11, 12 each coincide with the fold lines 5, a connection surface 13 or 16 being formed toward the adjacent base 10, the meaning of which will be explained later. The layer flaps within the respective U-shaped cuts 9 have sections 14, 15 and sections 17, 18 which are separated from one another by the fold lines 7 and 8, respectively. The sections 14, 17 are provided to form web walls and are initially tab-shaped, which is why these sections are also referred to as web tabs 14, 17.

FIG. 2 shows a square wave as can be produced from part of the web of FIG. 1. Suitable tools for this are punches or rollers which gradually pull in the material web without the material being torn due to the shortening of the web. As can be seen, between the fold lines 1 to 4 wave crests 20, troughs 21 and ridges 22 are formed. In Fig. 3, the U-shaped cuts 9 and the fold lines 7, 8 are also drawn in the rectangular wave, from which it follows that the web surfaces 22 remain unchanged in the sandwich core layer, while the wave crests 20 in the connection surfaces 13 and the web flaps 14 with Tab surfaces 15 and the trough surfaces 21 are subdivided into the connecting surfaces 16 and the web flaps 17 with tab surfaces 18.

To form the folded honeycomb shown in Fig. 4, the sections 14 + 15 around the fold lines 5 down and section 15 bent upward about fold line 7. From the original wave crest surface 20, only the connection surface 13 thus remains in the plane of the crest. The procedure is similar with regard to the trough surfaces 21. Sections 17 + 18 are folded up and section 18 is then bent back into the horizontal. Press die dies with an upper tool and a lower tool can be used as tools for these bending and folding processes. Finger-like bending plungers are provided on the upper tool, which bend the tabs 14, 15 downward until the lower die is reached, on which the tab 15 is bent horizontally. Finger-like bending plungers are also provided on the lower tool, which bend the tabs 17, 18 upwards until the upper die is reached, where the tab 18 is bent horizontally. The finger-like plungers fill the spaces 23 and 24 which are formed between the web walls 22 and 14 or 22 and 17 before they are withdrawn. Due to the folding and bending, the cut edges 11 and 12 come into contact with the web surface 22 and can be connected to it by suitable measures, for example by means of the adhesive or soldering material strips 19. As can be seen, the folding honeycomb offers larger connection surfaces 13 and 16 as well as tab surfaces 15 , 18 for connecting cover layers, so that a shear-resistant composite is easy to manufacture.

In the embodiment of FIG. 4, the connection surfaces 13 and the tab surfaces 18 extend to different sides, while one can also choose the same folding side, as shown in FIG. 5. In this case, the tabs 15, 18 are not initially bent by the bending plungers, rather this only takes place in a separate step when the bending plungers are withdrawn. Alternatively, different sets of bending rams (also pivotable) can be used to create the folding structure shown. The honeycomb cells form the differently oriented, vertical walls from the web surfaces 22 and the web flaps 14, 17. There are connection surfaces 13, 18 and 15, 16 both on the top and on the bottom.

If the cut edges 11, 12 are not connected (bonded) to the web walls 22 touching them by gluing, soldering or welding, the shear stiffness of the sandwich structure, which consists of the sandwich core layer and the bonded cover layers, is somewhat reduced. This low rigidity is sufficient for some applications. The cut edges 11, 12 are preferably bonded to the web walls in order to obtain maximum shear rigidity and shear strength.

FIG. 6 shows a modification of the cut and fold pattern compared to FIG. 1. Instead of a single vertical fold line sheet 5 for the vertical web flaps 14, 17 there are now two fold line sheets 5 and 6 displaced against one another. As can be seen, the U-shaped cuts 9 offset from row to row. In a modification of Fig. 1 and in accordance with Fig. 3, the U-shaped cuts 9 are open to the left, i.e. the fold line 5 or 6 is always arranged to the left of the associated U-shaped cut 9. This represents a possible variation that can be important in the manufacture of the honeycomb.

The folding honeycomb according to FIG. 7 was produced based on the cutting and folding pattern of FIG. 6. The tabs 15 or 18, which would stand in the way of the finger-like bending ram, were subsequently folded over.

A top view of the honeycomb is shown in FIG. 8. The web walls 22 can be deformed in a wave shape, either by pulling apart the rectangular folded honeycomb structure or by pressing the folded honeycomb structure in rows. After expansion, a honeycomb-like pattern is obtained, as shown in FIG. 9. After contraction, a fish band pattern is obtained, as shown in Fig. 10. The honeycomb shape is reduced in the honeycomb form. In the Fish tape shape gives more flexibility, in both directions. This honeycomb shape is therefore particularly suitable for parts with double curvature. It goes without saying that, depending on the requirements, different cell sizes, densities and thicknesses can be achieved for the sandwich cores to be produced by expansion and contraction.

11 shows, the web walls 22 can also be folded with dislocations 25, 26. As a result, regions of the web walls 22 nestle against the edge regions of the web walls 14, 17, so that there is a flat connection between these web walls which are perpendicular to one another.

There are also ways of enlarging the connection areas between the cover layers and the sandwich core layer by creating edge strip areas on the upper and lower cut edges of the web walls 22.

One of these possibilities is to make the U-shaped cuts 9 as in Fig. 6, bottom row, i.e. with an acute angle between the base 10 and the respective leg 11, 12, so that triangular surfaces 27 of the wave crest surfaces 20 or the trough surfaces 21 remain, which can be used as connection surfaces for the cover layers. It goes without saying that the web walls 22 can be deformed toward the somewhat tapering web wall regions 14, 17 in order to be connected (bonded) to them along the gluing, soldering or welding points 19.

Another possibility opens up when using fabric as the material of the folded honeycomb. To a certain extent, tissue can be deformed in the tissue plane, so that edge bends can be produced at the upper and lower cutting edges 11, 12, which can be fixed by impregnation material of the tissue.

If fold lines 1 and 4 and 2 and 3 are not parallel, sandwich core layers with varying thickness are obtained. The cuts 9 are adapted to the different thicknesses of the core layer. If necessary, the structure obtained can be stretched on the thicker side and on the thinner side compress to get even width.

A combined rolling and punching process with interlocking steps can be used to manufacture the folding honeycomb. The following steps can be considered when producing the sandwich core layer with bonded cutting edges: a) a web of the intended material is provided; b) U-shaped cuts 9 are made in rows to form web flaps which are separated from one another by connecting surfaces 13, 16; c) the web is folded into rectangular waves to form wave crest surfaces 20, trough surfaces 21 and web surfaces 22; d) the web flaps 14, 17 are folded out of the respective plane of the wave crest or wave valley, the connecting surfaces 13, 16 remaining in these planes. To form further tabs or connecting surfaces 15, 18, the free ends of the web flaps are bent over. e) The cut edges 11, 12 are firmly connected (bonded) to the web surfaces 22. The connection process depends on the material used for the flat web from which the sandwich core layer is made. Gluing, soldering and welding are possible.

Fig. 12 shows a boundary shape of a square wave that takes on a pulse shape. The wave crest surface 20 is extremely narrow, i.e. the fold lines 2, 3 are fused together. Accordingly, only areas of the trough surface 21 are provided with U-cuts, as indicated in FIG. 13. After the web flaps have been folded out, the structure shown in FIG. 14 is produced.

15 shows a further flat web with a cutting and folding pattern. Horizontal fold lines 31, 32, 33, 34 and vertical fold lines 35 and 36 are provided which form a grid. There are also two staggered sets of meandering notches 37 and 39, each with a central section 40 and two lateral ones Have sections 41, 42. The middle section 40 runs in the middle of the adjacent lines 35, 36. As a result, connecting surfaces 43 and 45 are formed between the horizontal folding lines 32, 33, while connecting surfaces 46 and 48 are formed between the folding lines 34 and 31. In the narrower strip 55 and 57 between lines 35 and 36 there are still fields 44 which will form part of the web walls, as will be described. Between the sheets of fold lines 35 and 36 there are also wider strips 56 and 58, which are divided into square fields 50, 51, 52.

The web shown in FIG. 15 is folded in a zigzag manner, as shown in FIG. 16. The wider strips 56, 58 are offset from one another by the dimension of the narrower strips 55, 57 and overlap one another by this dimension.

In a further step, the folding structure of FIG. 16 is folded in a wave shape transversely to the strips around the folding lines 31, 32, 33, 34, rectangular waves being generated in the final state while maintaining the covering structure according to FIG. 16. The structure of FIG. 17 is then pulled apart, with rotations about the folded edges which result in the cut edges 41, 42 being aligned vertically and the cut edges 40 being aligned horizontally in the sandwich core layer. The edges 41, 42 come into contact with the fields 50, 51, 52 and can be connected to them by gluing, soldering or welding. By moving the structure closer together, a certain surface coverage of web areas in the fields 44 and 52 can also be achieved, as a result of which the quality of the connection can be improved.

18 is a perspective illustration of a detail from the sandwich core layer in a state immediately before the surfaces assume their final position, but pulled apart somewhat for the sake of illustration. In practice, the structure shown is compressed, as a result of which the fields 50, 52, 51, 52, 50 etc. belong to web walls in the form of a rectangular wave and the fields 44 are aligned perpendicularly and in alignment with the web walls 52. Such areas are therefore connected to each other. This is shown in Fig. 19, which shows a top view of the sandwich core layer.

The sandwich core layer consists of narrower and wider strips 55, 56, 57, 58, which are connected at least along the folded edges 36 in the areas 43 and the folded edges 32 or 34 in the fields 44. The narrower strips 55, 57 form square waves perpendicular to the sandwich core layer plane, and the wider strips 56, 58 form square waves in this sandwich core layer. The surfaces 43 represent wave crests and the surfaces 46 wave troughs of the strip 55, to which, however, the surfaces 48 are added as wave crests and the surfaces 45 as wave troughs of the neighboring strip 57, in order to provide a connecting strip 59 on the top (FIG. 19) with the staggered ones Form surfaces 43, 48 and an underside connecting strip 60 also with offset surfaces 45, 46. The flanks 44 of the square waves of the narrower strips 55 and 57 and the flanks 52 of the square waves of the wider strips 56, 58 lie in the sandwich core layer and form web walls or parts of web walls there.

The hexagonal folded honeycombs described below are made as before from flat or flat bodies, for example thin metal sheet, plastic film, fabric, sheet-like bevel composite material (with carbon, aramid or glass fibers) or fiber-reinforced paper (Nomex ^® paper), but it will also considered normal paper or cardboard. The flat material is provided with incisions and then serves as the starting material for the folding.

20 shows a flat path with periods of horizontal fold lines 1, 2, 3, 4 and periods of vertical fold lines 5, 6, 7, 8. The fold points can be prepared by embossing lines. Between the fold lines 2 and 3 as well as 4 and 1 are cuts 9 which cut out a rectangular area in the case of FIG. 1. The cuts 9 can be slightly extended in the direction of the fold lines 5 and 8 or 6 and 7. Such cuts can be made by punching.

Interrupted, strip-shaped areas 20 are formed between the fold lines 2 and 3, which also contain bridging sections 13 in addition to the cuts 9 already mentioned, and interrupted, strip-shaped areas 21 are formed between the fold lines 4 and 1, which also contain bridging sections 16 in addition to the incisions 9 . Between the interrupted, strip-shaped regions 20 and 21 are continuous strip-shaped regions 22 which are interspersed with the periodic fold lines 5, 6, 7 and 8. As can be seen, the strip-shaped regions 22 are over the

Bridging sections 13 and 16 are connected to one another, so that the material provided for folding consists of a coherent flat body.

20 can be folded in two mutually perpendicular directions, specifically rectangular waves can be generated, the strip-shaped regions 20 forming the wave crests, the strip-shaped regions 21 forming the wave troughs and the strip-shaped regions 22 forming the wave flanks. The corrugation in the direction perpendicular thereto is achieved by bending or partially folding around fold lines 5 to 8, which is referred to here as "pleating". Trapezoidal waves are generated, which are referred to here as "half-honeycomb waves with wave crests and wave sinks".

Fig. 21 shows an intermediate form with half-honeycomb waves from three strip-shaped areas 22. As can be seen, the material of Fig. 20 is pleated so that the bridging sections 13 are aligned with the shaft ridges, while the bridging sections 16 are aligned with the shaft sinks.

In Fig. 21 are two side by side Shaft sinks with 22a and 22b and two adjacent wave crests designated 22c and 22d. If you now fold the half-honeycomb shaft with the part 22a around the fold line 2, so that the wave runs along a vertical plane, and fold the strip-shaped region with the part 22b around the fold line 3, so that the half-honeycomb shaft also runs along a vertical plane, The shaft sinks 22a and 22b touch each other and a row 23 of hexagonal honeycombs is formed, which correspond to the top row in FIG. 22. With this folding, the bridging parts 16 are simultaneously bent back into the horizontal about the folding line 4, and the half honeycomb shaft with the part 22d is folded in such a way that the half honeycomb waves are vertical, in which case the surfaces 22c and 22d touch and can be permanently connected to one another. This creates the second row 24 of cells in FIG. 22, which is offset from the first row 23, as is the case with honeycomb structures.

As a result, the folded honeycomb structure of FIG. 22 provided with bridging parts was created by folding wave structures in directions perpendicular to each other, which promises simple manufacture because this can be done by rolling.

23 shows an exemplary embodiment of a blank with U-shaped cuts 9. This forms flaps which are divided into two flap sections 14, 15 and 17, 18 by the fold line 7 and 5, respectively. The other features correspond to the embodiment according to FIG. 20. The flap section 14 is bent down and the flap section 15 is placed horizontally, while the flap section 17 is bent upwards and the flap section 18 is also placed horizontally. After folding in two different directions, as described with reference to FIGS. 21 and 22, the flap sections 14 and 17 become respective transverse webs which penetrate the respective cells 23 and 24, and the flap sections 15 and 18 become connecting surfaces, which span the respective cells 23, 24 as indicated in FIG. 24. The tab sections 15 and 18 offer additional connection surfaces for a possible sandwich cover layer.

25 shows a further possibility of designing the folded honeycomb. The starting material again has U-shaped cuts 9, but the flaps 14 and 17 formed thereby are not interrupted by fold lines. The flaps 14 and 17 are bent vertically upwards or downwards, which results in stiffening webs within the respective cells.

26 shows a further possibility of designing the folded honeycomb, namely the tabs 14, 17 are left in their respective plane 20 or 21. With a corresponding length of the tabs 14, 17 they adjoin the bridging sections 13, 16 and can be glued to the edges of the cell walls 22. If the tabs 14, 17 are of corresponding length, it is also possible to hide the ends of the tabs 14 below the respective adjacent bridging sections 13 in order to achieve a natural cohesion. The same applies to the ends of the tabs 17 and

Bridging sections 16. Finally, it is also possible to attach the tabs 14, 17 to their respective bridging sections 13, 16 (by gluing or the like) in order to obtain a continuous cover layer which spans the cells and thus solidifies the honeycomb.

FIG. 27 shows a cut for a transition between cells of different heights of the honeycombs, specifically a wedge-shaped tapering area, and FIG. 28 outlines such honeycombs. Since the strips 22 form the cell walls, the strips 22 have to become wider for taller cells. If the edges of the cell walls are to lie in the boundary surfaces 70, 71 of the wedge shape, the height of the cell wall of each cell on the side of the wedge tip must be lower than on the side of the Wedge extension. The respective width of the strips 22 is therefore variable - also locally, within the strips 22 - as can be seen in FIG. 27. The flaps 14 and 17 are used as additional cover strips, and their front free end 15, 18 is inserted under the respective adjacent bridging part 13 and 16, respectively. 27 contains some narrow punching waste 72. It is of course also possible to shorten the tabs 14, 17 at their respective free ends so that they just touch the bridging parts 13, 16 after the production of the half honeycomb shafts. It goes without saying that the flaps 14, 17 can also be glued to the free edges of the cell walls, as is known for the cover layers of sandwich structures.

While in the previous exemplary embodiments the regions 20 or the regions 21 each had a constant width, it is also possible to vary the width of these regions 20, 21, for example to make the regions 20 increasingly wider than the regions 21 (FIG. 29). This creates a curvature of the honeycomb transversely to the direction of the strip (FIG. 30), and the surface portions generated with the wave crest surfaces 20 span the surfaces generated by the wave trough portions, as is desirable, for example, in the case of a wing profile on the wing nose.

The following must be added to the production of the folding honeycombs described:

As a first step, flat material is fed in, whereby fold lines 1-8 can be embossed, but this is not absolutely necessary.

As a second step, the cuts 9 are made, for example by punching rolls.

As a third step, the continuous strip-shaped areas 22 are folded trapezoidally around the lines 5, 6, 7, 8, ie the half-honeycomb waves are produced with wave crests and wave sinks. The dimension of the material is shortened in the feed direction or in Cross direction. Rollers with trapezoidal teeth on the top and bottom of the material are used, which interlock so that the half-honeycomb waves are created. In order to adapt the tool to different widths of the continuous strip-shaped regions 22, it is possible to assemble the rollers from individual plug-in gears, which are driven by a common spline shaft.

In an intermediate step, activatable adhesive surfaces can be applied in the strips between the fold lines 6 and 7 and 8 and 5, which make up the wave crests and wave sinks in FIG. 21.

The next step is to bend flaps 14 and 15, if there are any and should be bent over.

The next step is the folding along the continuous folding lines 1, 2, 3 and 4, square waves being produced, in the wave crests or wave troughs of which the connection surfaces 13 and 16 come to lie. The material is shortened again.

In the context of the invention, approximated square waves are also to be understood, as they arise in the production of honeycombs with changing honeycomb heights (FIG. 28) or in the case of curved honeycombs (FIG. 30).

As a last step, the wave crests or wave sinks of the half honeycomb waves are connected to one another, if such a connection is provided for the structure. Adhesion is the preferred type of connection, but welding and soldering are also possible.

If the shaft crests or shaft sinks are not to be glued to one another, it is also possible to fasten the tabs 14, 17 to the bridging sections, in order to ensure a certain cohesion of the honeycomb.

Before the shaft crests or shaft sinks are fastened to one another or the flaps to the bridging sections, the structure can be kept in the form which it is to take on definitively. The honeycomb then assumes, for example, a shell shape without internal stresses, which as Core layer for a sandwich structure has diverse applications.

Since the manufacturing process largely works with rollers, low manufacturing costs can be expected. For this reason, the production of packaging material made of cardboard or paper is also considered. Compared to the usual corrugated cardboard, the new packaging material has a better compressive strength and does not buckle easily under bending loads. In addition, the work load is significantly greater under impact loads, i.e. the suitability as damping material for the transport of packaged goods is improved.

When the folded honeycomb is deformed, many webs and walls are affected, so that a large deformation energy can be absorbed. This makes the honeycomb suitable for many crash structures that involve energy consumption. Fig. 31 shows a blank of material that can be deep drawn or similarly deformed. Above all, light metal comes into consideration, but fabric and fiber structures can also be permanently deformed from a layer level, possibly also with the contribution of heat and moisture (paper, cardboard). The intended deformation is indicated by fold line groups 1, 2, 3, 4 or 5, 6, 7, 8. Slit-like cuts 9 run along the fold lines 1, 2, 3, 4, between which strip-shaped regions 20, 21, 22 extend. With regard to the strip-shaped regions 20, the slots 9 face each other, and this also applies to the strip-shaped regions 21, but the slot-like incisions 9 of the region 20 are offset from one another with respect to the slot-like incisions 9 of the region 21. Bridging sections 13 and 16 are provided between the slot-like incisions 9, so that the web shown forms a coherent, flat body.

The strip-shaped regions 22 are deformed into half-honeycomb waves, as is shown in FIG. 32. The shaft sinks are 22a and 22b and Wave crests designated 22c and 22d. The strip-shaped regions 20, 21 are aligned with the wave crests or wave sinks. The respective half-waves are connected to one another at the bridging sections 13 and 16.

To produce the folded honeycomb structure of FIG. 33, the intermediate shape of FIG. 32 is folded around fold lines 2, 3, 4, 1 in the manner described in the description of FIG. 21. The shaft sinks 22a and 22b and then the wave crests 22c and 22d are brought to overlap with one another ^" and optionally bonded to one another, so that the hexagonal honeycomb structure of FIG. 22 is formed as the middle layer in FIG. 33 If nothing has been cut away, the strip-shaped regions 20, 21 are retained and cover the hexagonal folded honeycomb structure obtained from the strip-shaped regions 22. This structure of Fig. 33 inherently shows a certain stability, but bonding the cut edges to the contact surfaces can result in considerable stability Increased stability can be achieved, which is therefore preferred.

Depending on the material from which the folded honeycomb according to FIG. 33 is made, it is suitable as a lightweight structure, as a packaging material or as a crash structure.

Claims

claims

Folded honeycomb, in particular as a sandwich core layer, formed from a plurality of cells of the same type arranged in rows, with the following features: the cells have lateral cell walls which connect to one another in a ring and to the

Opening sides of the cell are bounded by cover layer levels; the cells are each in at least one

Cover layer level partially or completely

Bridging sections (13, 16) bridged; the folding honeycomb is made of a coherent, flat surface

Body folded; the flat body is divided into a first plurality of continuous, strip-shaped areas (22) and into a second plurality of strip-shaped areas (20,

21) divided; the second strip-shaped areas (20, 21) have

Cuts (9) and the bridging sections (13, 16) which connect the first strip-shaped regions (22) to one another; the first, strip-shaped areas (22) are opposite the second, strip-shaped areas (20,

21) folded by about 90 °, the

Bridging sections (13, 16) of a second strip-shaped region (20, 21) connect adjacent, first strip-shaped regions (22).

Folding honeycomb according to claim 1 with the following features: the cell walls are separated by two series of web walls (14,

17, 22; 44, 50, 51, 52) are formed; the first series of web walls (22; 44, 52) extends on average in a first direction; the second series of web walls (14, 17; 50, 51) extends in a second direction transverse to the first direction; the web walls (14, 17, 22; 44, ^'50, 51, 52) are cutting edges (11, 12; 41, 42); limits of the planar body and folding edges (35, 36 5, 6, 7, 8); a first group of connection surfaces (13, 16; 43, 46) is formed by sections of the flat body which have remained in the cover layer planes and which are formed by three folded edges (1,

2, 3, 4, 5, 6; 31, 32, 33, 34, 35, 36) and a cutting edge (10; 40) are limited.

3. Folded honeycomb according to claim 2, characterized in that a second group of connection surfaces (15, 18; 45, 48) is formed by folded sections of the flat body, which are folded into the cover layer plane and by at least two cut edges (10, 11, 12th ; 40, 41, 42) are limited.

4. Folded honeycomb according to claim 2 or 3, characterized in that a third group of connection surfaces (27) is formed by sections of the flat body which are folded by the web walls in at least one cover layer plane and transversely to the first or second group of connection surfaces extend.

5. Folded honeycomb according to one of claims 1 to 4, characterized in that cut edges (11, 12; 40), which are in contact with web walls, are connected to them by gluing, soldering or welding.

6. Folded honeycomb according to one of claims 1 to 5, characterized in that the flat body along passing Fold lines (1, 2, 3, 4) are folded into rectangular waves, which comprise a plurality of wave crest surfaces (20) and trough surfaces (21) from the second strip-shaped regions (20, 21) and the first series of web walls (22) from the first Strip-shaped areas (22) form that the cuts (9) in the planar body to form the second series of web walls (14, 17) are U-shaped, the cutting edges (11, 12) according to the legs of the U or acute coincident with the continuous fold lines (1, 2, 3, 4) and the cutting edge (10) according to the base of the U run transversely to the continuous fold lines (1, 2, 3, 4) that the U-shaped cuts (9) are arranged in rows along the wave crest surfaces (20) and / or the wave trough surfaces (21) at such intervals that the first group of the connection surfaces (13, 16) are formed and that the web walls (14, 17) of the second side the respective level of the wave crest and / or d it is folded out into the honeycomb layer along tab fold lines (5, 6).

7. folded honeycomb according to claim 6, characterized in that the tabs within the U-shaped cuts (9) are bent at their free ends to form tab surfaces which form the second group of connecting surfaces (15, 18).

8. Folded honeycomb according to claim 6 or 7, characterized in that the tab fold lines (5) of adjacent rows of the U-shaped cuts (9) are aligned with one another (Fig. 1).

9. folding honeycomb according to claim 6 or 7, characterized in that the flap folding lines (5, 6) of adjacent rows of the U-shaped cuts (9) are offset from each other.

10. Folded honeycomb according to one of claims 6 to 9, characterized in that the U-shaped cuts (9) of adjacent rows are open on the same side.

11. Folded honeycomb according to one of claims 6 to 9, characterized in that the U-shaped cuts (9) of adjacent rows are open on different sides.

12. Folding honeycomb according to one of claims 9 to 11, characterized in that the web walls (22) of the first series are deformed transversely to their plane.

13. Folded honeycomb according to claim 12, characterized in that opposing web walls (22) are deformed away from one another to form hexagonal folded honeycombs (Fig. 9).

14. Folded honeycomb according to claim 12, characterized in that opposing web walls (22) are deformed towards each other to form fish band patterns (Fig. 10).

15. Folded honeycomb according to claim 12, characterized in that the web walls (22) of the first series are deformed in stages in order to put on the web walls (14, 17) of the second series (Fig. 11).

16. Folded honeycomb according to one of claims 2 to 5, characterized in that the strip-shaped areas of the flat body are subdivided into narrower and wider strips (55, 56, 57, 58) which are separated from one another by folded edges (35, 36) and cut edges ( 37, 39) are separated, that the narrower strips (55, 57) form rectangular waves in planes perpendicular to the longitudinal extent of the folded honeycomb layer, the wave crests (43, 48) or the trough surfaces (45, 46) of adjacent narrow strips (55, 57) alternately forming the first (43, 46 ) or the second (45, 48) group of the connecting surfaces and the flank surfaces (44) form part of the first series of the web walls, and that the wider strips (56, 58) form square waves in the plane of the folded honeycomb layer, the wave top surfaces ( 50) and the trough surfaces (51) represent the second series of the web walls, while the flank surfaces (52) together with the flank surfaces (44) of the narrower strips (55, 57) form the first series of the web walls.

17. Folded honeycomb according to claim 16, characterized in that the wave crest surfaces (43, 48) or trough surfaces (45, 46) of the narrower strips (55, 57) are half as wide as the flank surfaces (44).

18. Folded honeycomb according to claim 16 or 17, characterized in that the wave crest surfaces (50) and the wave trough surfaces (51) of the wider strips (56, 58) are square.

19. A method for producing a folded honeycomb layer according to one of claims 6 to 15, comprising the following steps: a) a flat body made of metal, plastic, fabric, fiber composite or fiber-reinforced paper, optionally with prepared adhesive, soldering or welding connection points (19), will be provided; b) U-shaped cuts (9) are made in rows in the body to prepare web walls (14, 17) of a second series separated from each other by pads

(13, 16) a first group are separated; c) the flat body is folded into rectangular waves to form wave crest surfaces (20), wave trough surfaces (21) and web surfaces (22) of a first series; d) the web walls (14, 17) of the second series are folded out of the respective plane of the wave crest or the wave valley into the folded honeycomb layer, the connecting surfaces (13, 16) remaining in these wave crest or wave valley planes.

20. The method according to claim 19, characterized in that the ends of the web walls (14, 17) are bent to form tab surfaces (15, 18) which form a second group of the connection surfaces.

21. The method according to claim 19 or 20, characterized in that the U-shaped cuts (9) are made in the rows so that the flap fold lines (5) of the web walls (14, 17) of adjacent rows are aligned.

22. The method according to claim 19 or 20, characterized in that the U-shaped cuts (9) are made in the rows so that the flap fold lines (5, 6) of the web walls (14, 17) of adjacent rows are offset from one another.

23. The method according to any one of claims 19 to 22, characterized in that the cut edges (11, 12) of the legs of the U are firmly connected to the web surfaces (22) along prepared connection points (19).

24. The method according to claim 23, characterized in that the web walls (22) of the first series are deformed transversely to their plane to form hexagonal folded honeycombs.

25. The method according to claim 23, characterized in that the web walls (22) of the first series are deformed transversely to their plane to form fish band patterns.

26. The method according to claim 23, characterized in that the web walls (22) of the first series are deformed transversely to their plane to form step edges which partially rest against the web walls (14, 17) of the second series.

27. A method for producing a folded honeycomb layer according to one of claims 16 to 18 with the following steps: a) the planar body is meandered with cuts (37, 39) which are offset from one another and along fold lines (35, 36) into narrower and wider stripes (55, 56, 57, 58) divided; b) the flat body is folded overlapping along the fold lines (35, 36); c) the folding structure is deformed into square waves, so that the narrower and wider strips (55, 56, 57, 58) form individual, interlocking square waves; d) the nested rectangular waves are pulled apart, the narrower strips (55, 57) with their rectangular waves arranged in planes perpendicular to the folded honeycomb plane and the wider strips (56, 58) with their rectangular waves arranged in the folded honeycomb plane.

28. The method according to claim 27, characterized in that the flank surfaces (44) of the square waves of the narrower strips (55, 57) are aligned or slightly overlapping with the flank surfaces (52) of the wider strips (56, 58) and brought with them Formation of the first series of web walls (44, 52) are firmly connected.

29. The method according to any one of claims 19 to 28, characterized in that the flat body is formed from metal, plastic, fabric, fiber composite material or paper.

30. Folded honeycomb according to claim 1 with the following features: the first strip-shaped regions (22) are crimped with wave crests (22c, 22d) and wave sinks (22a, 22b) to form half-honeycomb waves; Adjacent half honeycomb waves touch with their wave crests or wave sinks to form a row of cells each; each bridging section (13, 16) bridges an associated cell.

31. Folding honeycomb according to claim 30, characterized in that the shaft crests (22c, 22d) or the shaft sinks (22a, 22b) are permanently connected to one another.

32. Folded honeycomb according to claim 30 or 31, characterized in that the fold spacing of the first strip-shaped regions (22) are uniform and four folds (5, 6, 7, 8) form a period.

33. Folded honeycomb according to claim 32, characterized in that the bridging sections (13, 16) on the second strip-shaped areas (20, 21) in periods corresponding to the folds (5, 6, 7, 8) of the first strip-shaped areas (22) arranged are.

34. Folded honeycomb according to claim 32 or 33, characterized in that the cuts (9) in the second strip-shaped areas (20, 21) comprise three quarters of a period.

35. folded honeycomb according to one of claims 30 to 34, characterized in that the cuts (9) are rectangular.

36. Folding honeycomb according to one of claims 30 to 34, characterized in that the cuts (9) are U-shaped and form tabs (14, 17).

37. Folding honeycomb according to claim 36, characterized in that the tabs (14, 17) remain in the wave region (20) or the wave trough plane (21).

38. Folded honeycomb according to claim 36, characterized in that the tabs (14, 17) are folded out of their respective corrugated or trough plane.

39. Folding honeycomb according to claim 38, characterized in that the free ends (15, 18) of the tabs (14, 17) are folded into the local wave trough plane or wave region.

40. folded honeycomb according to one of claims 30 to 34, characterized in that the cuts (9) are slot-shaped, so that the second strip-shaped regions (20, 21) are formed continuously.

41. Folded honeycomb according to claim 40, characterized in that the slot-shaped cuts (9) face each other in pairs on the second strip-shaped areas (20, 21) and slot pairs of adjacent second strip-shaped areas (20, 21) are offset from one another.

42. Folded honeycomb according to one of claims 30 to 41, characterized in that the strip width of the first strip-shaped areas (22) vary according to the desired local layer thickness of the folded honeycomb.

43. Folded honeycomb according to one of claims 30 to 42, characterized in that the strip width of the second strip-shaped regions for the wave crests (20) and the wave troughs (21) are selected differently to give local curvatures of the folded honeycomb.

44. A method for producing a folded honeycomb comprising the following steps: a) a flat body made of metal, plastic, fabric, fiber composite material, fiber-reinforced paper or ordinary paper or cardboard is provided; b) the flat body is provided with cuts (9) to form first strip-shaped regions (22) and second strip-shaped regions (20, 21) which alternate with one another, the second strip-shaped regions (20, 21)

Have bridging sections (13, 16) which connect the first strip-shaped regions (22) to one another; c) the first strip-shaped regions (22) are deformed transversely to the strip direction to give half-honeycomb waves with wave crests and wave sinks; d) the flat body deformed in the first strip-shaped regions (22) is along fold lines

(1, 2, 3, 4), which separate the first and second strip-shaped regions (20, 21, 22) from one another, folded into rectangular waves, the bridging sections coming to lie in the wave crests (20) or wave troughs (21); e) flat parts (22a, 22b, 22c, 22d) are brought to rest with opposing flat parts (22a, 22b, 22c, 22d).

45. The method according to claim 44, characterized in that it is in the applied flat parts to the wave crests (22c, 22d) and the shaft sinks (22a, 22b) of the half-honeycomb waves, which are firmly connected to each other.

46. The method according to claim 44, characterized in that it is in the applied to the flat parts

Bridging section (13, 16) and the ends of tabs (14, 17), which are formed from the cuts (9), and that these adjacent parts are firmly connected to one another.

47. The method according to claim 44 or 45, characterized in that the deformation of the first strip-shaped regions (22) takes place by bending or folding.

48. The method according to claim 44 or 45, characterized in that the deformation of the first strip-shaped regions (22) is carried out by deep drawing.

49. Use of the folded honeycomb according to one of claims 1 to 18 or 30 to 43 as packaging material.

50. Use of the folded honeycomb according to one of claims 1 to 18 or 30 to 43 as a crash structure.