Title of Invention	METHOD FOR MANUFACTURING A THREE-DIMENSIONALLY DEFORMABLE, SHEET-LIKE REINFORCING STRUCTURE
Abstract	A method for manufacturing a three-dimensionally deformable, sheet-like reinforcing structure, wherein material attenuations (3) are incorporated into a sheet-like, cellular base material, distributed over an area of the base material, by means of cutting or sawing, said material attenuations (3) sub-dividing the base material into a plurality of material cells (1) which are delineated from each other by the material attenuations (3) but are still connected to each other.

Title of Invention

METHOD FOR MANUFACTURING A THREE-DIMENSIONALLY DEFORMABLE, SHEET-LIKE REINFORCING STRUCTURE

Abstract

A method for manufacturing a three-dimensionally deformable, sheet-like reinforcing structure, wherein material attenuations (3) are incorporated into a sheet-like, cellular base material, distributed over an area of the base material, by means of cutting or sawing, said material attenuations (3) sub-dividing the base material into a plurality of material cells (1) which are delineated from each other by the material attenuations (3) but are still connected to each other.

Full Text	Method for Manufacturing a Three-dimensionally Deformable, Sheet-like Reinforcing Structure The invention relates to a method for manufacturing a three-dimensionally deformable, sheet- like reinforcing structure from a likewise sheet-like, cellular base material. The base material can in particular be a foamed plastic which is reinforced with reinforcing structures or also a non- reinforced foamed plastic. The invention also relates to a reinforcing structure manufactured in accordance with the method, and to its use for manufacturing a composite material, a "composite", for which the reinforcing structure serves as a core material. Cellular reinforcing structures and their use as core materials of composites is known from WO 98/10919 A2. The reinforcing structures are arranged between covering layers of the respective composite in a sandwich construction, for manufacturing light but nonetheless rigid composites. The reinforcing structures serve as spacers for the covering layers and increase the bending and buckling resistance of the composites. In order to be able to fixedly connect the covering layers of a composite, between which a reinforcing structure is inserted, to each other by means of a joiner, for example by means of an adhesive or synthetic resin, a honeycombed reinforcing structure is used comprising hexagonal material cells and thin bridges which connect them to each other. The joiner penetrates the cavities of the reinforcing structure between the material cells in the region of the bridges, such that at least in the region of the cavities, a material connection to the covering layers is guaranteed. The structuring into material cells and connecting bridges provides the reinforcing structure with a flexibility such as is needed for manufacturing three-dimensionally deformed composites. However, producing the cavities or other types of material attenuations to the required precision and a desirable efficiency is problematic. Precisely incorporating the material .attenuations, for example by means of milling, laser treatment or water jet treatment, is very time-consuming and therefore cost-intensive. It is an object of the invention to precisely and efficiently manufacture reinforcing structures of the type cited. The subject of the invention is a method for manufacturing a three-dimensionally deformable, sheet-like reinforcing structure, wherein material attenuations are incorporated or machined or worked into a sheet-like, cellular base material, distributed over the area of the base material, said material attenuations sub-dividing the base material into a plurality of material cclLs which are delineated from each other by the material attenuations but are still connected to each other. The material cells are formed by the cellular base material. The material attenuations are preferably incorporated in a regular distribution, such that a correspondingly regular distribution of the material cells and thus structuring of the reinforcing structures is obtained. The material cells preferably each exhibit the same shape and size. The same preferably applies to the material attenuations. The material cells can in particular be polygons, preferably equilateral polygons. They are preferably hexagonal in a top view onto the reinforcing structure. When incorporating the material attenuations in a batch operation, the base material can be provided in the form of board material which can in particular be plate-like or, in more flexible boards, also mat-like. Flexible base material can also be provided with the material attenuations as a web product in a continuous method. The base material can exhibit a thickness of a few millimetres, for example at least 5 mm, and a thickness of up to a few centimetres, preferably at most 20 mm. The cellular material can have a predominantly open porosity, or more preferably a closed porosity, in order to prevent water or even moisture from entering. Foamed plastic materials are preferred base materials, wherein foamed thermoplasts or also foamed thermosets can in particular be used. Advantageous plastic foam materials are thus for example polyethylene tcrcphthalatc (PET) foams or polystyrene (PS) foams, as well as more flexible polyethylene (PE) foams or polypropylene (PP) foams or also, as an example of a thermosetting material, polyurethane (PUR) foams. The plastic foam material can be reinforced, i.e. can comprise reinforcing structures embedded in the foam material, or can be used with no reinforcement. The base material is preferably extruded and simultaneously foamed. In accordance with the invention, the material attenuations are incorporated into the base material by means of cutting or sawing. The word "or" is used here, as elsewhere in accordance with the invention, always in its usual logical sense, i.e. it includes the meaning of "either ... or" and also the meaning of "and", providing the respective context does not rule out any of these meanings. Accordingly, the material attenuations can be incorporated solely by cutting or solely by sawing or - as corresponds to preferred method embodiments - by a multi-stage process which includes cutting and sawing and preferably consists of cutting and sawing. In a preferred multi-stage incorporating process, the first stage involves cutting in accordance with the shape of the material attenuations, and after the cutting process, which itself can comprise one or more stages, sawing in accordance with the shape of the material attenuations. The material attenuations are sawn out. Although the material attenuations can be incorporated in the form of recesses, material attenuations which are shaped as passages, i.e. cavities extending from the upper to the lower side of the reinforcing structure, are preferred, since material attenuations extending through the structure are advantageous with regard to three-dimensional dcformability. When manufacturing a composite, the reinforcing structure can be penetrated in the region of the passages by a free- flowing joiner, in order to connect the covering layers of the composite to each other through the reinforcing structure in a material connection. After the material attenuations have been incorporated, material webs or bridges remain which connect the material cells to each other. After cutting or sawing - preferably, after the final cutting or sawing step - these connecting bridges are compressed, thus permanently reducing their cross-section. The cellular base material is compacted in the region of the bridges. The bridges advantageously fall short of an upper side and lower side of the reinforcing structure, such that when the reinforcing structure is embedded between two covering layers, for example two metallic or plastic covering layers, the bridges do not touch said covering layers. Compacting the bridges by compression is an inexpensive way of making the bridges short of the upper and lower side of the reinforcing structure. When the reinforcing structure is inserted between covering layers of a composite to be manufactured, and the material attenuations arc- shaped - as is preferred - as passages in the reinforcing structure, the material attenuations form a channel system between the covering layers which extends continuously over the entire area of the reinforcing structure and can accordingly be penetrated by the joiner parallel to the sheet-like reinforcing structure, such that the reinforcing structure is in particular suitable for being filled with joiner by vacuum injection, wherein the joiner can be injected from the side. On the other hand, however, the composite can also be manufactured by placing the reinforcing structure onto one of the covering layers, filling the material attenuations with the joiner, and placing the other of the covering layers onto the reinforcing structure. In preferred embodiments, the material cells are compacted near the surface and thus rounded on an upper side or a lower side, along at least a part of their edges formed by incorporating the material attenuations. On the one hand, rounding counteracts a notching effect caused by sharp edges, while on the other hand, the area of the material attenuations on the upper side or lower side of the reinforcing structure is increased, which advantageously increases the area available to the joiner for the material connection to the covering layers or at least to one of the covering layers and thus increases the stability of the composite. The cellular material can be compacted in the region of the bridges or the material cells can be compacted near the surface at ambient temperature, for example room temperature, or in a heated state of the cellular material. A heatable or non-heatable bridge presser for compacting the bridges or a heatable or non-hcatable top presser for compacting near the surface, and as applicable for compacting only near the edges of the material cells, can be used. If the cellular material is compacted while warm, it is preferably heated to a temperature just below its melting point and compacted at this temperature. A preferred manufacturing method includes at least one separating process, namely cutting or sawing, and at least one compacting process, namely compacting the cellular material in the region of the bridges or along the edges of the material cells. In particularly preferred method embodiments, the material attenuations are incorporated sequentially by cutting and then sawing, and at least the bridges arc then compacted; more preferably, both cited compacting processes are performed, for example firstly compacting the bridges and then compacting at least the edges of the material cells near the surface. A preferred method therefore comprises at least three stages, more preferably at least four. Proceeding from the cellular base material, the reinforcing structure is preferably manufactured only by cutting or sawing and additionally at least one of the two compacting processes. For incorporating the material attenuations, it is advantageous if multiple cutting knives or saw blades are arranged on a cutting tool or sawing tool, facing an upper side of the base material, and are moved, for example pushed, into or preferably through the base material by a movement of the tool towards a lower side of the base material. The term "upper side of the base material" here is merely intended to indicate the side of the base material facing the cutting knives or saw blades, and is not intended to state whether the separating tool is arranged vertically above or below the base material, wherein the base material can also be processed in a vertical orientation, with the separating tool then arranged alongside it. If the base material consists of boards, it expediently lies on a support, and the cutting knives or saw blades are pushed from top to bottom into or preferably through the base material. The cutting knives or saw blades are preferably arranged together in groups, wherein the cutting knives or saw blades of each group respectively produce a material attenuation which - as seen in a top view - is framed by the adjacent material cells and bridges. Within each of the groups, the cutting knives or saw blades of the respective group are arranged close to each other in accordance with the shape of the material cells and attenuations, respectively. For producing hexagonal material cells, each of the groups consists of three cutting knives or saw blades which, within each group, are arranged close to each other in accordance with the angles of the hexagons. In the case of for example square or rhombic material cells, the individual groups would be formed by cutting knives or saw blades arranged crosswise or in the shape of an ;'X" with respect to each other. In the case of the preferred hexagons, the cutting knives or saw blades of each group are in a Y-shape with respect to each other, in cross-section; in the case of the particularly preferred equilateral hexagons, they are each at an angle of 120° to each other. The cutting knives or saw blades of the individual groups each cut or saw one limb of the material attenuations. Instead of arranging separately produced cutting knives or saw blades into groups of cutting knives or saw blades, the groups can each be formed in one piece. Preferably, the cutting knives or saw blades are moved, expediently pushed, into or through the base material at least substantially vertically with respect to the surface forming the upper side of the base material; the pushing direction is preferably exactly orthogonal to the surface in question. In preferred embodiments, the cutting knives or saw blades are only moved in a single plane when cutting or sawing, wherein the cutting or sawing movement is a linear movement in preferred embodiments. The saw blades preferably each exhibit a thickness which corresponds to the width of the material attenuations. If groups are formed, as is preferred, then the saw blades of each group form a cross-section which corresponds to the cross-section of the material attenuations. In such embodiments, the saw blades saw into or preferably through the base material by means of a linear movement or a movement in one plane only, i.e. they are not moved transverse to their pushing direction relative to the base material, in order to produce the material attenuations. Incorporating the material attenuations by means of simply moving the cutting knives or saw blades reciprocally in this way expedites the cutting or sawing process. In preferred embodiments, the cutting knives or saw blades comprise a cutting edge or row of saw teeth which is inclined with respect to the pushing direction. The cutting edge or row of saw- teeth preferably extends up to a tip of each cutting knife or saw blade which protrudes in the pushing direction. The cutting process thus involves stabbing and then, while moving the cutting knife in the pushing direction, a cutting engagement with the base material which continues transverse to the pushing direction in the base material. The sawing process proceeds according to the same pattern, but with a sawing engagement between the saw blade and the cellular material instead of the cutting engagement. When cutting or sawing in batches, the separating tool preferably performs a reciprocal stroke movement composed of the pushing movement into and preferably through the cellular material and the reverse movement. The separating tool can be fitted with cutting knives or saw blades, preferably groups of cutting knives or groups of saw blades, over its entire area in accordance widi the structuring of the reinforcing structure to be provided, such that the cutting or sawing process can be performed in a single stroke for each initial board. In alternative embodiments, the cutting or sawing tool only comprises a beam or other support, from which the cutting knives or saw blades, preferably the groups of cutting knives or groups of saw blades, project alongside each other in a row along a line. During a stroke movement, material attenuations are thus only produced alongside each other on a line, such that the separating tool has to be subsequently moved transverse to the support relative to the initial board and successively incorporates one line of material attenuations after the other. Instead of the tool or as applicable in addition, the initial board can also be moved spatially, in order to incorporate one line of material attenuations after the other. If the base material is sufficiently flexible that it can be wound onto a reel even without the material attenuations, then incorporating the material attenuations is possible in a continuous method. Such materials, for example PE or PP foams, are unwound in a continuous method embodiment from a reel and guided through a roller gap formed by two rollers rotating opposite to each other or at least by one roller together with a counter-pressure means which is fixed as applicable. The material attenuations are incorporated in the gap. The roller or more preferably at least one roller of the pair of rollers forming the gap is fitted with the cutting knives or saw blades. The rollers or the roller and its counter-pressure means which is formed differently co- operate as a male and female mould. In preferred method embodiments, the web is successively guided through multiple gaps, preferably through at least two gaps, wherein the male mould of one gap is fitted with cutting knives and the female mould of the at least one other gap is fitted with saw blades. If, as is preferred, the separating process involves at least one cutting process and then at least one sawing process, the base material is preferably fed automatically to the cutting tool and then to the sawing tool, in a batch operation for example by means of a conveyor belt or other form of continuous conveying means, and in a continuous process as a web product which is conveyed through roller gaps arranged sequentially in the conveying direction. In addition to the manufacturing method, the subject of the invention also includes a reinforcing structure as such, obtained by means of the method in accordance with the invention, and also a composite in a sandwich construction which comprises at least two covering layers and, between the covering layers, an inserted reinforcing structure of the type in accordance with the invention, as well as a joiner which permeates the reinforcing structure and connects it in a material connection to both covering layers, and which is preferably formed by a synthetic resin or an adhesive. The covering layers can in particular be plastic layers or also metal layers, for example light metal layers. The composite can also comprise additional covering layers and additional reinforcing structures, and can in particular be manufactured in a multiple sandwich construction. A double sandwich comprising mree covering layers, namely an outer, a middle and another outer covering layer and two reinforcing structures respectively arranged between the outer covering layers and the middle covering layer, may serve as an example. It is also possible to arrange one or more reinforcing structures produced in accordance with the invention, one on top of the other, between covering layers, wherein the lower or lowermost reinforcing structure is adjacent to a lower covering layer, and the upper or uppermost reinforcing structure is adjacent to an upper covering layer. Preferred features are also disclosed in the sub-claims and combinations of the sub-claims. An example embodiment of the invention is explained below on the basis of figures. Features disclosed by the example embodiment, each individually and in any combination of features, advantageously develop the subjects of the claims and also the embodiments described above. There is shown: Figure 1 a reinforcing structure in a top view; Figure 2 the reinforcing structure in a cross-section; Figure 3 the deformed reinforcing structure in a cross-section; Figure 4 a cutting knife; Figure 4a a group of cutting knives, in a view from below; Figure 5 a saw blade; Figure 5a a group of saw blades, in a view from below; Figure 6 a bridge presser; Figure 7 a top presser; and Figure 8 a composite. Figure 1 shows a reinforcing structure made of a cellular material, preferably a plastic foam material. Reinforcing structures, for example filaments, can be embedded in the cellular material, however the cellular material is preferably a non-reinforced cellular material. The reinforcing structure consists of polygonal material cells 1, in the example embodiment hexagonal material cells 1, and relatively thin connecting bridges 2. The material cells 1 are connected on each of their sides to the nearest adjacent material cell 1 via a central connecting bridge 2. Due to their hexagonal shape, each of the material cells 1 is connected to its nearest adjacent material cells 1 via six connecting bridges 2. The width of the material cells 1, as measured in each direction of the plane of view, is clearly larger than the length of the connecting bridges 2. The space between the respectively nearest adjacent material cells 1 is free, apart from the connecting bridges 2. The cavities which thus remain free between the material cells 1 form material attenuations 3 as compared to a non-structured plate-like or mat-like cellular base material. Depending on the bending resistance of the plate-like or mat-like base material, these cavities or material attenuations 3 facilitate - or even at all enable to an appreciable extent - three- dimensional defotmability. Primarily, the reinforcing structure 1, 2 can be three-dimensionally deformed, i.e. bent about multiple axes which do not point parallel to each other, by shifting the material cells 1 relative to each other, namely by deforming the connecting bridges 2. The reinforcing structure 1 is therefore suitable as a core material for three-dimensionally curved lightweight composites in a sandwich construction. The material attenuations 3 also in particular enable the penetration of a joiner 17, for example a synthetic resin or adhesive mass, by which two covering layers can be fixedly connected to each other in a material connection via the reinforcing structure 1, 2. The joiner 17 preferably completely fills the spaces remaining free between the material cells 1 in the region of the material attenuations 3 and accordingly forms a honeycombed reinforcing structure for the covering layers in the hardened composite, or if the reinforcing structure 1, 2 is structured differently, forms this predetermined other reinforcing structure. Figure 2 shows the reinforcing structure 1, 2 in a non-deformed initial state in which the reinforcing structure 1, 2 substantially forms a planar mat or plate structured in accordance with the shape of the material cells 1. Figure 3 shows the reinforcing structure 1, 2 in a deformed state in which nearest adjacent material cells 1 point at an inclined angle to each other, due to bending in the connecting bridge 2 respectively connecting them. The reinforcing structure 1, 2 is produced in batches from a plate-like or mat-like cellular base material, an initial board, or continuously from a web material in multiple method steps. The initial board or web product exhibits a material thickness which at least substantially corresponds to the material cells 1 throughout. It is a homogenous, non-structured board or web material which however exhibits a microscopic and as applicable also macroscopic cellular structure having a correspondingly low density. For the example embodiment, it may be assumed that it is a plastic foam material. Such foam materials can in particular be produced by extrusion and separated into the initial boards to be processed, or can be wound onto a reel as a web product if the base material is correspondingly flexible. The material attenuations 3 are incorporated into such a cellular base material in a multi-stage method by cutting and then sawing. Once the multi-stage separating process - which involves at least one cutting process and at least one sawing process - has been completed, the connecting bridges 2 remaining between the material cells 1 and material attenuations 3 thus obtained are compacted by compression and their cross-section thus reduced, such that the compacted bridges 2 fall short of both the upper side and the lower side of the material cells 1, as can for example be seen in Figures 2 and 3. The bridges 2 can be compacted with or without being heated. Reducing the cross-section of the bridges 2 by compression represents a method which is simple and therefore inexpensive to perform mechanically and which provides contact areas for the joiner 17 to the respective covering layer of the composite in the region of the material attenuations 3. Before the bridges 2 are compacted or more preferably after the bridges 2 have been compacted, or as applicable at the same time as the bridges 2 are compacted, the material cells 1 arc compacted by means of compression in a near-surface range of depth on each of the upper side and lower side, in order to round the edges of the material cells 1 which are still sharp-edged after the separating process. In Figures 1 to 3, the already rounded edges are provided with the reference sign 4. The material cells 1 can also either be heated at least in their near-surface range of depth to support compacting this material, or can also be compacted at ambient temperature, by means of pressure only. On the one hand, rounding the edges 4 prevents notching effects and on the other hand advantageously increases the contact area available to the joiner 17 to the covering layer of the composite situated on the respective upper or lower side of the reinforcing structure 1,2. Figures 4 and 5 respectively show a cutting knife 5 and a saw blade 7 in a lateral view. For incorporating the material attenuations 3, a plurality of cutting knives 5 are arranged on a cutting tool and an equal plurality of saw blades 7 are arranged on a sawing tool. The cutting tool can for example be formed by a cutting beam on which the cutting knives 5 are arranged, projecting from the cutting beam towards the base material to be processed. The sawing tool can similarly comprise such a sawing beam for the saw blades 7 which are arranged on the sawing beam. projecting towards the base material. The cutting knives 5 and the saw blades 7 are arranged on the respective tool in groups of three, each consisting of three cutting knives 5 or saw blades 7 which point in a Y-shape with respect to each other, as shown in the views from below in Figures 4a and 5a. The respective tool can be moved back and forth in a pushing direction which is indicated on the cutting knife 5 and saw blade 7 by a directional arrow, such that in the respective stroke movement, the cutting knives 5 of the cutting tool or saw blades 7 of the sawing tool are pushed towards and through the base material in the pushing direction. The cutting knives 5 each comprise a tip protruding in the pushing direction and, inclined from this with respect to the pushing direction - in the example embodiment, inclined at a constant angle of inclination - a cutting edge 6 comparable to a guillotine, such that the cutting knives 5 stab into the base material with their tip first and then continue to cut through along the respective cutting edge 6, in order to obtain an even cut. The sawing process is performed after cutting, wherein the saw blades 7 are positioned exactly opposite the incorporated cuts and then moved in the plotted pushing direction relative to the initial material provided with the cuts. The saw blades 7 are moved forwards along the cuts. They likewise comprise a tip at their protruding ends in the pushing direction, comparable to the cutting knives 5, from which a row of saw teedi 8 inclined with respect to the pushing direction tapers off counter to the pushing direction, comparable to the cutting edge 6. As a first approximation, the effect of the saw blades 7 is comparable to a jig or sabre saw, however due to the inclined row of saw teeth 8, a force acting in the pushing direction is sufficient in order to widen the previously produced cut by a sawing process continuing from the respective tip of the saw blade towards a respectively nearest adjacent connecting bridge 2 or continuing away from a respectively nearest adjacent connecting bridge 2. During sawing, the material attenuation 3 is widened in accordance with the thickness of the saw blades 7, in particular the thickness of the rows of saw teeth 8. The cutting knives 5 exhibit a width of preferably at least 300 µm and preferably at most 800 urn. The saw blades 7 preferably exhibit a larger width of preferably at least 400 um and preferably at most 2 mm. Figure 6 illustrates a bridge presser 9 using which one of the bridges 2 can be compressed and thus compacted after cutting and sawing, such that the cross-section of the bridge 2 in question is permanently reduced. On a lower side 10, via which it presses against the bridge 2 during compression, the bridge presser 9 comprises a central recess 11. The recess 11 is semi- cylindrical - in the example embodiment, semi-circular cylindrical - and extends over the entire lower side 10. The compacted bridge 2 comes to rest in the recess 11 at the end of the compacting stroke. The bridges 2 are each compressed by means of two bridge pressers 9, one of which faces and opposes the upper side of the reinforcing structure 1, 2 and the other of which faces and opposes the lower side of the reinforcing structure 1,2. The bridge pressers 9 are moved towards each other in pairs - as applicable, one of the bridge pressers 9 can remain at rest while only the other one is moved - until the bridge 2 in question has been compacted to the desired final shape. The movement direction of the bridge presser 9 is indicated by a directional arrow. In a preferred embodiment, bridge pressers 9 project from a forming tool in a number and arrangement which corresponds to the number and arrangement of the bridges 2 to be compacted. Another such forming tool is arranged facing the other side of the reinforcing prc- structure produced by cutting and sawing. The bridge pressers 9 each exhibit a thickness which at least substantially corresponds to the length of the bridges 2. Figure 7 shows a top presser 12 by means of which one of the material cells 1 is compacted on its upper side or lower side by compression, wherein the material cell 1 is primarily compacted along the edges 4 obtained by sawing, wherein the edge 4 in question is primarily rounded. The top presser 12 comprises a hollow space 13 on its lower side facing the reinforcing structure 1,2. The hollow space 13 is trough-shaped. During compression, it accommodates the upper or lower side of one of the material cells 1. At its circumferential edge, the hollow space 13 tapers out in a curve, the shape of which corresponds to the desired curve for the edges 4 of the material cells 1. A forming tool is arranged facing each of the upper side and lower side of the reinforcing structure 1, 2 and is provided with a number of top pressers 12 corresponding to the number and shape of the material cells 1. In this forming step, the material cells 1 arc compressed between the top pressers 12 of the two tools and thus compacted near the surface, at least in the region of the edges 4. The reinforcing structure 1. 2 can be produced from an initial board made of the cellular base material in a batch process as follows: As already mentioned, the cutting knives 5 are arranged on the cutting tool along a support of the tool in groups of three cutting knives 5 each, wherein the cutting knives 5 of each group of three are arranged in a Y-shape with respect to each other. The saw blades 7 are correspondingly arranged along a support of the sawing tool. Initial boards of the cellular material are conveyed through successively and in steps, below the cutting tool and the sawing tool. In each stroke movement of the cutting tool, the cutting knives 5 produce one cut in the region of the material attenuations 3 to be provided. The cut regions are then sawn out by means of a stroke movement of the sawing tool and the saw blades 7 projecting from it. The boards respectively provided after these processes as reinforcing pre-structures are conveyed to the forming tool comprising the bridge pressers 9, where the bridges 2 are compacted. In the final step, the edges 4 of the material cells 1 are rounded by means of another forming tool bearing a plurality of top pressers 12. In a variant, the order of the two compacting operations can be reversed. It is also possible to compact the bridges 2 and round the edges 4 of the material cells 1 at the same location, and as applicable at the same time. In such embodiments, a combined forming tool comprises both the bridge pressers 9 and the top pressers 12, wherein the bridge pressers 9 can be moved in the compressing direction relative to the top pressers 12. The bridges 2 and material cells 1 can be compacted while cold, at ambient temperature. In a further development, the bridge pressers 9 are tempered to a temperature slightly below the melting point of the cellular base material. In another further development, the top pressers 12 are tempered to such a temperature. It is also possible to correspondingly temper the bridge pressers 9 and the top pressers 12. Figure 8 shows a composite comprising an upper covering layer 15 and a lower covering layer 16, each consisting of a plastic material. The reinforcing structure 1, 2 is sandwiched between the covering layers 15 and 16. The material attenuations 3 are filled with a joiner 17, preferably a hardened resin. The joiner 17 conforms to the honeycombed structure of the material cells 1 and fills the former material attenuatioas 3. Reference signs 1 material cell 2 bridge 3 material attenuation 4 edge 5 cutting knife 6 cutting edge 7 saw 8 row of saw teeth 9 bridge presser 10 lower side of bridge presser 11 recess in bridge presser 12 top presser 13 hollow space 14 circumferential edge 15 covering layer 16 covering layer 17 joiner Patent claims 1. A method for manufacturing a three-dimensionally deformable, sheet-like reinforcing structure, wherein material attenuations (3) are incorporated into a sheet-like, cellular base material, distributed over an area of the base material, by means of cutting or sawing, said material attenuations (3) sub-dividing the base material into a plurality of material cells (1) which are delineated from each other by the material attenuations (3) but are still connected to each other. 2. The method according to the preceding claim, wherein the material attenuations (3) are incorporated in such a way that bridges (2) remain between adjacent material attenuations (3) and connect adjacent material cells (1) to each other. 3. The method according to the preceding claim, wherein a cross-sectional area of the bridges (2) is reduced by means of compression. 4. The method according to me preceding claim, wherein the cross-sectional area is reduced by heating and compressing the heated bridges (2). 5. The method according to any one of the preceding two claims, wherein the bridges (2) are compacted, such that they fall short of an upper side and lower side of the respectively adjacent material cells (1). 6. The method according to any one of the preceding claims, wherein the material cells (1) are compacted near the surface and thus rounded on an upper side or a lower side, along at least a part of edges (4) formed by incorporating the material attenuations (3). 7. The method according to the preceding claim, wherein the material cells (1) are heated at least in the region of the edges (4) to be rounded, and are compacted near the surface along the heated edges (4). 8. The method according to any one of the preceding claims, wherein cutting involves stabbing which preferably penetrates through the base material. 9. The method according to any one of the preceding claims, wherein sawing involves jig or sabre sawing which preferably penetrates through the base material. 10. The method according to any one of the preceding claims, wherein the material attenuations (3) are incorporated by cutting and then sawing. 11. The method according to the preceding claim, wherein cutting is performed in a cutting plane, and sawing is performed in the same cutting plane. 12. The method according to any one of the preceding claims, wherein the material attenuations (3) are produced in the base material in the form of recesses or preferably passages, by cutting or sawing. 13. The method according to any one of the preceding claims, wherein cutting is performed using cutting knives (5) or sawing is performed using saw blades (7) which arc only moved in a single cutting or sawing plane when incorporating the material attenuations (3). 14. The method according to any one of the preceding claims, wherein the material attenuations (3) are sawn using saw blades (7) which exhibit a thickness which corresponds to a width of the material attenuations (3). 15. The method according to any one of the preceding claims, wherein in order to incorporate the material attenuations (3), cutting knives (5) of a cutting tool or saw blades (7) of a sawing tool facing an upper side of the base material are moved into or through the base material towards a lower side of the base material. 16. The method according to the preceding claim, wherein the cutting knives (5) each comprise a cutting edge (6) which is inclined with respect to the movement direction, or the saw blades (7) each comprise a row of saw teeth (8) which is inclined with respect to the movement direction. 17. The method according to the preceding claim, wherein the cutting knives (5) or saw blades (7) comprise a tip protruding in the movement direction. 18. The method according to any one of the preceding claims, wherein plastic foam material is used as the base material, in which reinforcing structures are optionally embedded. 19. A reinforcing structure (1,2) manufactured according to any one of the preceding claims. 20. The use of the reinforcing structure (1,2) according to the preceding claim as a core structure between covering layers of a composite. 21. A composite, including: a) covering layers; b) a reinforcing structure (1, 2) according to any one of the preceding claims, arranged between the covering layers; c) and a joiner (17) which connects the covering layers to each other in a material connection, permeates the reinforcing structure (1, 2) in the region of the material attenuations (3) and encloses at least the sides of the material cells (1) of the reinforcing structure (1,2). A method for manufacturing a three-dimensionally deformable, sheet-like reinforcing structure, wherein material attenuations (3) are incorporated into a sheet-like, cellular base material, distributed over an area of the base material, by means of cutting or sawing, said material attenuations (3) sub-dividing the base material into a plurality of material cells (1) which are delineated from each other by the material attenuations (3) but are still connected to each other.

Full Text

Method for Manufacturing a Three-dimensionally
Deformable, Sheet-like Reinforcing Structure
The invention relates to a method for manufacturing a three-dimensionally deformable, sheet-
like reinforcing structure from a likewise sheet-like, cellular base material. The base material can
in particular be a foamed plastic which is reinforced with reinforcing structures or also a non-
reinforced foamed plastic. The invention also relates to a reinforcing structure manufactured in
accordance with the method, and to its use for manufacturing a composite material, a
"composite", for which the reinforcing structure serves as a core material.
Cellular reinforcing structures and their use as core materials of composites is known from WO
98/10919 A2. The reinforcing structures are arranged between covering layers of the respective
composite in a sandwich construction, for manufacturing light but nonetheless rigid composites.
The reinforcing structures serve as spacers for the covering layers and increase the bending and
buckling resistance of the composites. In order to be able to fixedly connect the covering layers
of a composite, between which a reinforcing structure is inserted, to each other by means of a
joiner, for example by means of an adhesive or synthetic resin, a honeycombed reinforcing
structure is used comprising hexagonal material cells and thin bridges which connect them to
each other. The joiner penetrates the cavities of the reinforcing structure between the material
cells in the region of the bridges, such that at least in the region of the cavities, a material
connection to the covering layers is guaranteed. The structuring into material cells and
connecting bridges provides the reinforcing structure with a flexibility such as is needed for
manufacturing three-dimensionally deformed composites.
However, producing the cavities or other types of material attenuations to the required precision
and a desirable efficiency is problematic. Precisely incorporating the material .attenuations, for
example by means of milling, laser treatment or water jet treatment, is very time-consuming and
therefore cost-intensive.

It is an object of the invention to precisely and efficiently manufacture reinforcing structures of
the type cited.
The subject of the invention is a method for manufacturing a three-dimensionally deformable,
sheet-like reinforcing structure, wherein material attenuations are incorporated or machined or
worked into a sheet-like, cellular base material, distributed over the area of the base material,
said material attenuations sub-dividing the base material into a plurality of material cclLs which
are delineated from each other by the material attenuations but are still connected to each other.
The material cells are formed by the cellular base material. The material attenuations are
preferably incorporated in a regular distribution, such that a correspondingly regular distribution
of the material cells and thus structuring of the reinforcing structures is obtained. The material
cells preferably each exhibit the same shape and size. The same preferably applies to the material
attenuations. The material cells can in particular be polygons, preferably equilateral polygons.
They are preferably hexagonal in a top view onto the reinforcing structure.
When incorporating the material attenuations in a batch operation, the base material can be
provided in the form of board material which can in particular be plate-like or, in more flexible
boards, also mat-like. Flexible base material can also be provided with the material attenuations
as a web product in a continuous method. The base material can exhibit a thickness of a few
millimetres, for example at least 5 mm, and a thickness of up to a few centimetres, preferably at
most 20 mm. The cellular material can have a predominantly open porosity, or more preferably a
closed porosity, in order to prevent water or even moisture from entering.
Foamed plastic materials are preferred base materials, wherein foamed thermoplasts or also
foamed thermosets can in particular be used. Advantageous plastic foam materials are thus for
example polyethylene tcrcphthalatc (PET) foams or polystyrene (PS) foams, as well as more
flexible polyethylene (PE) foams or polypropylene (PP) foams or also, as an example of a
thermosetting material, polyurethane (PUR) foams. The plastic foam material can be reinforced,
i.e. can comprise reinforcing structures embedded in the foam material, or can be used with no
reinforcement. The base material is preferably extruded and simultaneously foamed.
In accordance with the invention, the material attenuations are incorporated into the base
material by means of cutting or sawing. The word "or" is used here, as elsewhere in accordance

with the invention, always in its usual logical sense, i.e. it includes the meaning of "either ... or"
and also the meaning of "and", providing the respective context does not rule out any of these
meanings. Accordingly, the material attenuations can be incorporated solely by cutting or solely
by sawing or - as corresponds to preferred method embodiments - by a multi-stage process
which includes cutting and sawing and preferably consists of cutting and sawing.
In a preferred multi-stage incorporating process, the first stage involves cutting in accordance
with the shape of the material attenuations, and after the cutting process, which itself can
comprise one or more stages, sawing in accordance with the shape of the material attenuations.
The material attenuations are sawn out.
Although the material attenuations can be incorporated in the form of recesses, material
attenuations which are shaped as passages, i.e. cavities extending from the upper to the lower
side of the reinforcing structure, are preferred, since material attenuations extending through the
structure are advantageous with regard to three-dimensional dcformability. When manufacturing
a composite, the reinforcing structure can be penetrated in the region of the passages by a free-
flowing joiner, in order to connect the covering layers of the composite to each other through the
reinforcing structure in a material connection.
After the material attenuations have been incorporated, material webs or bridges remain which
connect the material cells to each other. After cutting or sawing - preferably, after the final
cutting or sawing step - these connecting bridges are compressed, thus permanently reducing
their cross-section. The cellular base material is compacted in the region of the bridges. The
bridges advantageously fall short of an upper side and lower side of the reinforcing structure,
such that when the reinforcing structure is embedded between two covering layers, for example
two metallic or plastic covering layers, the bridges do not touch said covering layers.
Compacting the bridges by compression is an inexpensive way of making the bridges short of the
upper and lower side of the reinforcing structure. When the reinforcing structure is inserted
between covering layers of a composite to be manufactured, and the material attenuations arc-
shaped - as is preferred - as passages in the reinforcing structure, the material attenuations form
a channel system between the covering layers which extends continuously over the entire area of
the reinforcing structure and can accordingly be penetrated by the joiner parallel to the sheet-like
reinforcing structure, such that the reinforcing structure is in particular suitable for being filled

with joiner by vacuum injection, wherein the joiner can be injected from the side. On the other
hand, however, the composite can also be manufactured by placing the reinforcing structure onto
one of the covering layers, filling the material attenuations with the joiner, and placing the other
of the covering layers onto the reinforcing structure.
In preferred embodiments, the material cells are compacted near the surface and thus rounded on
an upper side or a lower side, along at least a part of their edges formed by incorporating the
material attenuations. On the one hand, rounding counteracts a notching effect caused by sharp
edges, while on the other hand, the area of the material attenuations on the upper side or lower
side of the reinforcing structure is increased, which advantageously increases the area available
to the joiner for the material connection to the covering layers or at least to one of the covering
layers and thus increases the stability of the composite.
The cellular material can be compacted in the region of the bridges or the material cells can be
compacted near the surface at ambient temperature, for example room temperature, or in a
heated state of the cellular material. A heatable or non-heatable bridge presser for compacting
the bridges or a heatable or non-hcatable top presser for compacting near the surface, and as
applicable for compacting only near the edges of the material cells, can be used. If the cellular
material is compacted while warm, it is preferably heated to a temperature just below its melting
point and compacted at this temperature.
A preferred manufacturing method includes at least one separating process, namely cutting or
sawing, and at least one compacting process, namely compacting the cellular material in the
region of the bridges or along the edges of the material cells. In particularly preferred method
embodiments, the material attenuations are incorporated sequentially by cutting and then sawing,
and at least the bridges arc then compacted; more preferably, both cited compacting processes
are performed, for example firstly compacting the bridges and then compacting at least the edges
of the material cells near the surface. A preferred method therefore comprises at least three
stages, more preferably at least four. Proceeding from the cellular base material, the reinforcing
structure is preferably manufactured only by cutting or sawing and additionally at least one of
the two compacting processes.

For incorporating the material attenuations, it is advantageous if multiple cutting knives or saw
blades are arranged on a cutting tool or sawing tool, facing an upper side of the base material,
and are moved, for example pushed, into or preferably through the base material by a movement
of the tool towards a lower side of the base material. The term "upper side of the base material"
here is merely intended to indicate the side of the base material facing the cutting knives or saw
blades, and is not intended to state whether the separating tool is arranged vertically above or
below the base material, wherein the base material can also be processed in a vertical orientation,
with the separating tool then arranged alongside it. If the base material consists of boards, it
expediently lies on a support, and the cutting knives or saw blades are pushed from top to bottom
into or preferably through the base material.
The cutting knives or saw blades are preferably arranged together in groups, wherein the cutting
knives or saw blades of each group respectively produce a material attenuation which - as seen
in a top view - is framed by the adjacent material cells and bridges. Within each of the groups,
the cutting knives or saw blades of the respective group are arranged close to each other in
accordance with the shape of the material cells and attenuations, respectively. For producing
hexagonal material cells, each of the groups consists of three cutting knives or saw blades which,
within each group, are arranged close to each other in accordance with the angles of the
hexagons. In the case of for example square or rhombic material cells, the individual groups
would be formed by cutting knives or saw blades arranged crosswise or in the shape of an ;'X"
with respect to each other. In the case of the preferred hexagons, the cutting knives or saw blades
of each group are in a Y-shape with respect to each other, in cross-section; in the case of the
particularly preferred equilateral hexagons, they are each at an angle of 120° to each other. The
cutting knives or saw blades of the individual groups each cut or saw one limb of the material
attenuations. Instead of arranging separately produced cutting knives or saw blades into groups
of cutting knives or saw blades, the groups can each be formed in one piece.
Preferably, the cutting knives or saw blades are moved, expediently pushed, into or through the
base material at least substantially vertically with respect to the surface forming the upper side of
the base material; the pushing direction is preferably exactly orthogonal to the surface in
question.

In preferred embodiments, the cutting knives or saw blades are only moved in a single plane
when cutting or sawing, wherein the cutting or sawing movement is a linear movement in
preferred embodiments. The saw blades preferably each exhibit a thickness which corresponds to
the width of the material attenuations. If groups are formed, as is preferred, then the saw blades
of each group form a cross-section which corresponds to the cross-section of the material
attenuations. In such embodiments, the saw blades saw into or preferably through the base
material by means of a linear movement or a movement in one plane only, i.e. they are not
moved transverse to their pushing direction relative to the base material, in order to produce the
material attenuations. Incorporating the material attenuations by means of simply moving the
cutting knives or saw blades reciprocally in this way expedites the cutting or sawing process. In
preferred embodiments, the cutting knives or saw blades comprise a cutting edge or row of saw
teeth which is inclined with respect to the pushing direction. The cutting edge or row of saw-
teeth preferably extends up to a tip of each cutting knife or saw blade which protrudes in the
pushing direction. The cutting process thus involves stabbing and then, while moving the cutting
knife in the pushing direction, a cutting engagement with the base material which continues
transverse to the pushing direction in the base material. The sawing process proceeds according
to the same pattern, but with a sawing engagement between the saw blade and the cellular
material instead of the cutting engagement.
When cutting or sawing in batches, the separating tool preferably performs a reciprocal stroke
movement composed of the pushing movement into and preferably through the cellular material
and the reverse movement.
The separating tool can be fitted with cutting knives or saw blades, preferably groups of cutting
knives or groups of saw blades, over its entire area in accordance widi the structuring of the
reinforcing structure to be provided, such that the cutting or sawing process can be performed in
a single stroke for each initial board. In alternative embodiments, the cutting or sawing tool only
comprises a beam or other support, from which the cutting knives or saw blades, preferably the
groups of cutting knives or groups of saw blades, project alongside each other in a row along a
line. During a stroke movement, material attenuations are thus only produced alongside each
other on a line, such that the separating tool has to be subsequently moved transverse to the
support relative to the initial board and successively incorporates one line of material

attenuations after the other. Instead of the tool or as applicable in addition, the initial board can
also be moved spatially, in order to incorporate one line of material attenuations after the other.
If the base material is sufficiently flexible that it can be wound onto a reel even without the
material attenuations, then incorporating the material attenuations is possible in a continuous
method. Such materials, for example PE or PP foams, are unwound in a continuous method
embodiment from a reel and guided through a roller gap formed by two rollers rotating opposite
to each other or at least by one roller together with a counter-pressure means which is fixed as
applicable. The material attenuations are incorporated in the gap. The roller or more preferably at
least one roller of the pair of rollers forming the gap is fitted with the cutting knives or saw
blades. The rollers or the roller and its counter-pressure means which is formed differently co-
operate as a male and female mould. In preferred method embodiments, the web is successively
guided through multiple gaps, preferably through at least two gaps, wherein the male mould of
one gap is fitted with cutting knives and the female mould of the at least one other gap is fitted
with saw blades.
If, as is preferred, the separating process involves at least one cutting process and then at least
one sawing process, the base material is preferably fed automatically to the cutting tool and then
to the sawing tool, in a batch operation for example by means of a conveyor belt or other form of
continuous conveying means, and in a continuous process as a web product which is conveyed
through roller gaps arranged sequentially in the conveying direction.
In addition to the manufacturing method, the subject of the invention also includes a reinforcing
structure as such, obtained by means of the method in accordance with the invention, and also a
composite in a sandwich construction which comprises at least two covering layers and, between
the covering layers, an inserted reinforcing structure of the type in accordance with the
invention, as well as a joiner which permeates the reinforcing structure and connects it in a
material connection to both covering layers, and which is preferably formed by a synthetic resin
or an adhesive. The covering layers can in particular be plastic layers or also metal layers, for
example light metal layers. The composite can also comprise additional covering layers and
additional reinforcing structures, and can in particular be manufactured in a multiple sandwich
construction. A double sandwich comprising mree covering layers, namely an outer, a middle
and another outer covering layer and two reinforcing structures respectively arranged between

the outer covering layers and the middle covering layer, may serve as an example. It is also
possible to arrange one or more reinforcing structures produced in accordance with the
invention, one on top of the other, between covering layers, wherein the lower or lowermost
reinforcing structure is adjacent to a lower covering layer, and the upper or uppermost
reinforcing structure is adjacent to an upper covering layer.
Preferred features are also disclosed in the sub-claims and combinations of the sub-claims.
An example embodiment of the invention is explained below on the basis of figures. Features
disclosed by the example embodiment, each individually and in any combination of features,
advantageously develop the subjects of the claims and also the embodiments described above.
There is shown:
Figure 1 a reinforcing structure in a top view;
Figure 2 the reinforcing structure in a cross-section;
Figure 3 the deformed reinforcing structure in a cross-section;
Figure 4 a cutting knife;
Figure 4a a group of cutting knives, in a view from below;
Figure 5 a saw blade;
Figure 5a a group of saw blades, in a view from below;
Figure 6 a bridge presser;
Figure 7 a top presser; and
Figure 8 a composite.
Figure 1 shows a reinforcing structure made of a cellular material, preferably a plastic foam
material. Reinforcing structures, for example filaments, can be embedded in the cellular material,
however the cellular material is preferably a non-reinforced cellular material. The reinforcing
structure consists of polygonal material cells 1, in the example embodiment hexagonal material
cells 1, and relatively thin connecting bridges 2. The material cells 1 are connected on each of
their sides to the nearest adjacent material cell 1 via a central connecting bridge 2. Due to their
hexagonal shape, each of the material cells 1 is connected to its nearest adjacent material cells 1
via six connecting bridges 2. The width of the material cells 1, as measured in each direction of
the plane of view, is clearly larger than the length of the connecting bridges 2. The space

between the respectively nearest adjacent material cells 1 is free, apart from the connecting
bridges 2. The cavities which thus remain free between the material cells 1 form material
attenuations 3 as compared to a non-structured plate-like or mat-like cellular base material.
Depending on the bending resistance of the plate-like or mat-like base material, these cavities or
material attenuations 3 facilitate - or even at all enable to an appreciable extent - three-
dimensional defotmability. Primarily, the reinforcing structure 1, 2 can be three-dimensionally
deformed, i.e. bent about multiple axes which do not point parallel to each other, by shifting the
material cells 1 relative to each other, namely by deforming the connecting bridges 2. The
reinforcing structure 1 is therefore suitable as a core material for three-dimensionally curved
lightweight composites in a sandwich construction. The material attenuations 3 also in particular
enable the penetration of a joiner 17, for example a synthetic resin or adhesive mass, by which
two covering layers can be fixedly connected to each other in a material connection via the
reinforcing structure 1, 2. The joiner 17 preferably completely fills the spaces remaining free
between the material cells 1 in the region of the material attenuations 3 and accordingly forms a
honeycombed reinforcing structure for the covering layers in the hardened composite, or if the
reinforcing structure 1, 2 is structured differently, forms this predetermined other reinforcing
structure.
Figure 2 shows the reinforcing structure 1, 2 in a non-deformed initial state in which the
reinforcing structure 1, 2 substantially forms a planar mat or plate structured in accordance with
the shape of the material cells 1.
Figure 3 shows the reinforcing structure 1, 2 in a deformed state in which nearest adjacent
material cells 1 point at an inclined angle to each other, due to bending in the connecting bridge
2 respectively connecting them.
The reinforcing structure 1, 2 is produced in batches from a plate-like or mat-like cellular base
material, an initial board, or continuously from a web material in multiple method steps. The
initial board or web product exhibits a material thickness which at least substantially corresponds
to the material cells 1 throughout. It is a homogenous, non-structured board or web material
which however exhibits a microscopic and as applicable also macroscopic cellular structure
having a correspondingly low density. For the example embodiment, it may be assumed that it is
a plastic foam material. Such foam materials can in particular be produced by extrusion and

separated into the initial boards to be processed, or can be wound onto a reel as a web product if
the base material is correspondingly flexible.
The material attenuations 3 are incorporated into such a cellular base material in a multi-stage
method by cutting and then sawing. Once the multi-stage separating process - which involves at
least one cutting process and at least one sawing process - has been completed, the connecting
bridges 2 remaining between the material cells 1 and material attenuations 3 thus obtained are
compacted by compression and their cross-section thus reduced, such that the compacted bridges
2 fall short of both the upper side and the lower side of the material cells 1, as can for example
be seen in Figures 2 and 3. The bridges 2 can be compacted with or without being heated.
Reducing the cross-section of the bridges 2 by compression represents a method which is simple
and therefore inexpensive to perform mechanically and which provides contact areas for the
joiner 17 to the respective covering layer of the composite in the region of the material
attenuations 3.
Before the bridges 2 are compacted or more preferably after the bridges 2 have been compacted,
or as applicable at the same time as the bridges 2 are compacted, the material cells 1 arc
compacted by means of compression in a near-surface range of depth on each of the upper side
and lower side, in order to round the edges of the material cells 1 which are still sharp-edged
after the separating process. In Figures 1 to 3, the already rounded edges are provided with the
reference sign 4. The material cells 1 can also either be heated at least in their near-surface range
of depth to support compacting this material, or can also be compacted at ambient temperature,
by means of pressure only. On the one hand, rounding the edges 4 prevents notching effects and
on the other hand advantageously increases the contact area available to the joiner 17 to the
covering layer of the composite situated on the respective upper or lower side of the reinforcing
structure 1,2.
Figures 4 and 5 respectively show a cutting knife 5 and a saw blade 7 in a lateral view. For
incorporating the material attenuations 3, a plurality of cutting knives 5 are arranged on a cutting
tool and an equal plurality of saw blades 7 are arranged on a sawing tool. The cutting tool can for
example be formed by a cutting beam on which the cutting knives 5 are arranged, projecting
from the cutting beam towards the base material to be processed. The sawing tool can similarly
comprise such a sawing beam for the saw blades 7 which are arranged on the sawing beam.

projecting towards the base material. The cutting knives 5 and the saw blades 7 are arranged on
the respective tool in groups of three, each consisting of three cutting knives 5 or saw blades 7
which point in a Y-shape with respect to each other, as shown in the views from below in
Figures 4a and 5a. The respective tool can be moved back and forth in a pushing direction which
is indicated on the cutting knife 5 and saw blade 7 by a directional arrow, such that in the
respective stroke movement, the cutting knives 5 of the cutting tool or saw blades 7 of the
sawing tool are pushed towards and through the base material in the pushing direction. The
cutting knives 5 each comprise a tip protruding in the pushing direction and, inclined from this
with respect to the pushing direction - in the example embodiment, inclined at a constant angle
of inclination - a cutting edge 6 comparable to a guillotine, such that the cutting knives 5 stab
into the base material with their tip first and then continue to cut through along the respective
cutting edge 6, in order to obtain an even cut.
The sawing process is performed after cutting, wherein the saw blades 7 are positioned exactly
opposite the incorporated cuts and then moved in the plotted pushing direction relative to the
initial material provided with the cuts. The saw blades 7 are moved forwards along the cuts.
They likewise comprise a tip at their protruding ends in the pushing direction, comparable to the
cutting knives 5, from which a row of saw teedi 8 inclined with respect to the pushing direction
tapers off counter to the pushing direction, comparable to the cutting edge 6. As a first
approximation, the effect of the saw blades 7 is comparable to a jig or sabre saw, however due to
the inclined row of saw teeth 8, a force acting in the pushing direction is sufficient in order to
widen the previously produced cut by a sawing process continuing from the respective tip of the
saw blade towards a respectively nearest adjacent connecting bridge 2 or continuing away from a
respectively nearest adjacent connecting bridge 2. During sawing, the material attenuation 3 is
widened in accordance with the thickness of the saw blades 7, in particular the thickness of the
rows of saw teeth 8.
The cutting knives 5 exhibit a width of preferably at least 300 µm and preferably at most 800
urn. The saw blades 7 preferably exhibit a larger width of preferably at least 400 um and
preferably at most 2 mm.
Figure 6 illustrates a bridge presser 9 using which one of the bridges 2 can be compressed and
thus compacted after cutting and sawing, such that the cross-section of the bridge 2 in question is

permanently reduced. On a lower side 10, via which it presses against the bridge 2 during
compression, the bridge presser 9 comprises a central recess 11. The recess 11 is semi-
cylindrical - in the example embodiment, semi-circular cylindrical - and extends over the entire
lower side 10. The compacted bridge 2 comes to rest in the recess 11 at the end of the
compacting stroke. The bridges 2 are each compressed by means of two bridge pressers 9, one of
which faces and opposes the upper side of the reinforcing structure 1, 2 and the other of which
faces and opposes the lower side of the reinforcing structure 1,2. The bridge pressers 9 are
moved towards each other in pairs - as applicable, one of the bridge pressers 9 can remain at rest
while only the other one is moved - until the bridge 2 in question has been compacted to the
desired final shape. The movement direction of the bridge presser 9 is indicated by a directional
arrow. In a preferred embodiment, bridge pressers 9 project from a forming tool in a number and
arrangement which corresponds to the number and arrangement of the bridges 2 to be
compacted. Another such forming tool is arranged facing the other side of the reinforcing prc-
structure produced by cutting and sawing. The bridge pressers 9 each exhibit a thickness which
at least substantially corresponds to the length of the bridges 2.
Figure 7 shows a top presser 12 by means of which one of the material cells 1 is compacted on
its upper side or lower side by compression, wherein the material cell 1 is primarily compacted
along the edges 4 obtained by sawing, wherein the edge 4 in question is primarily rounded. The
top presser 12 comprises a hollow space 13 on its lower side facing the reinforcing structure 1,2.
The hollow space 13 is trough-shaped. During compression, it accommodates the upper or lower
side of one of the material cells 1. At its circumferential edge, the hollow space 13 tapers out in a
curve, the shape of which corresponds to the desired curve for the edges 4 of the material cells 1.
A forming tool is arranged facing each of the upper side and lower side of the reinforcing
structure 1, 2 and is provided with a number of top pressers 12 corresponding to the number and
shape of the material cells 1. In this forming step, the material cells 1 arc compressed between
the top pressers 12 of the two tools and thus compacted near the surface, at least in the region of
the edges 4.
The reinforcing structure 1. 2 can be produced from an initial board made of the cellular base
material in a batch process as follows:

As already mentioned, the cutting knives 5 are arranged on the cutting tool along a support of the
tool in groups of three cutting knives 5 each, wherein the cutting knives 5 of each group of three
are arranged in a Y-shape with respect to each other. The saw blades 7 are correspondingly
arranged along a support of the sawing tool. Initial boards of the cellular material are conveyed
through successively and in steps, below the cutting tool and the sawing tool. In each stroke
movement of the cutting tool, the cutting knives 5 produce one cut in the region of the material
attenuations 3 to be provided. The cut regions are then sawn out by means of a stroke movement
of the sawing tool and the saw blades 7 projecting from it.
The boards respectively provided after these processes as reinforcing pre-structures are conveyed
to the forming tool comprising the bridge pressers 9, where the bridges 2 are compacted. In the
final step, the edges 4 of the material cells 1 are rounded by means of another forming tool
bearing a plurality of top pressers 12. In a variant, the order of the two compacting operations
can be reversed. It is also possible to compact the bridges 2 and round the edges 4 of the material
cells 1 at the same location, and as applicable at the same time. In such embodiments, a
combined forming tool comprises both the bridge pressers 9 and the top pressers 12, wherein the
bridge pressers 9 can be moved in the compressing direction relative to the top pressers 12. The
bridges 2 and material cells 1 can be compacted while cold, at ambient temperature. In a further
development, the bridge pressers 9 are tempered to a temperature slightly below the melting
point of the cellular base material. In another further development, the top pressers 12 are
tempered to such a temperature. It is also possible to correspondingly temper the bridge pressers
9 and the top pressers 12.
Figure 8 shows a composite comprising an upper covering layer 15 and a lower covering layer
16, each consisting of a plastic material. The reinforcing structure 1, 2 is sandwiched between
the covering layers 15 and 16. The material attenuations 3 are filled with a joiner 17, preferably a
hardened resin. The joiner 17 conforms to the honeycombed structure of the material cells 1 and
fills the former material attenuatioas 3.

Reference signs
1 material cell
2 bridge
3 material attenuation
4 edge
5 cutting knife
6 cutting edge
7 saw
8 row of saw teeth
9 bridge presser
10 lower side of bridge presser
11 recess in bridge presser
12 top presser
13 hollow space
14 circumferential edge
15 covering layer
16 covering layer
17 joiner

Patent claims
1. A method for manufacturing a three-dimensionally deformable, sheet-like reinforcing
structure, wherein material attenuations (3) are incorporated into a sheet-like, cellular base
material, distributed over an area of the base material, by means of cutting or sawing, said
material attenuations (3) sub-dividing the base material into a plurality of material cells (1)
which are delineated from each other by the material attenuations (3) but are still
connected to each other.
2. The method according to the preceding claim, wherein the material attenuations (3) are
incorporated in such a way that bridges (2) remain between adjacent material attenuations
(3) and connect adjacent material cells (1) to each other.
3. The method according to the preceding claim, wherein a cross-sectional area of the bridges
(2) is reduced by means of compression.
4. The method according to me preceding claim, wherein the cross-sectional area is reduced
by heating and compressing the heated bridges (2).
5. The method according to any one of the preceding two claims, wherein the bridges (2) are
compacted, such that they fall short of an upper side and lower side of the respectively
adjacent material cells (1).

6. The method according to any one of the preceding claims, wherein the material cells (1)
are compacted near the surface and thus rounded on an upper side or a lower side, along at
least a part of edges (4) formed by incorporating the material attenuations (3).
7. The method according to the preceding claim, wherein the material cells (1) are heated at
least in the region of the edges (4) to be rounded, and are compacted near the surface along
the heated edges (4).
8. The method according to any one of the preceding claims, wherein cutting involves
stabbing which preferably penetrates through the base material.
9. The method according to any one of the preceding claims, wherein sawing involves jig or
sabre sawing which preferably penetrates through the base material.
10. The method according to any one of the preceding claims, wherein the material
attenuations (3) are incorporated by cutting and then sawing.
11. The method according to the preceding claim, wherein cutting is performed in a cutting
plane, and sawing is performed in the same cutting plane.
12. The method according to any one of the preceding claims, wherein the material
attenuations (3) are produced in the base material in the form of recesses or preferably
passages, by cutting or sawing.
13. The method according to any one of the preceding claims, wherein cutting is performed
using cutting knives (5) or sawing is performed using saw blades (7) which arc only moved
in a single cutting or sawing plane when incorporating the material attenuations (3).
14. The method according to any one of the preceding claims, wherein the material
attenuations (3) are sawn using saw blades (7) which exhibit a thickness which
corresponds to a width of the material attenuations (3).

15. The method according to any one of the preceding claims, wherein in order to incorporate
the material attenuations (3), cutting knives (5) of a cutting tool or saw blades (7) of a
sawing tool facing an upper side of the base material are moved into or through the base
material towards a lower side of the base material.
16. The method according to the preceding claim, wherein the cutting knives (5) each
comprise a cutting edge (6) which is inclined with respect to the movement direction, or
the saw blades (7) each comprise a row of saw teeth (8) which is inclined with respect to
the movement direction.
17. The method according to the preceding claim, wherein the cutting knives (5) or saw blades
(7) comprise a tip protruding in the movement direction.
18. The method according to any one of the preceding claims, wherein plastic foam material is
used as the base material, in which reinforcing structures are optionally embedded.
19. A reinforcing structure (1,2) manufactured according to any one of the preceding claims.
20. The use of the reinforcing structure (1,2) according to the preceding claim as a core
structure between covering layers of a composite.
21. A composite, including:

a) covering layers;
b) a reinforcing structure (1, 2) according to any one of the preceding claims, arranged
between the covering layers;
c) and a joiner (17) which connects the covering layers to each other in a material
connection, permeates the reinforcing structure (1, 2) in the region of the material
attenuations (3) and encloses at least the sides of the material cells (1) of the
reinforcing structure (1,2).

A method for manufacturing a three-dimensionally deformable, sheet-like reinforcing structure, wherein material
attenuations (3) are incorporated into a sheet-like, cellular base material, distributed over an area of the base material, by means
of cutting or sawing, said material attenuations (3) sub-dividing the base material into a plurality of material cells (1) which are
delineated from each other by the material attenuations (3) but are still connected to each other.

Documents:

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Patent Number

269089

Indian Patent Application Number

734/KOLNP/2010

PG Journal Number

40/2015

Publication Date

02-Oct-2015

Grant Date

30-Sep-2015

Date of Filing

25-Feb-2010

Name of Patentee

ESC EXTENDED STRUCTURED COMPOSITES GMBH & CO. KG

Applicant Address

OSTSTRASSE 70, 32051 HERFORD, GERMANY

Inventors:

#	Inventor's Name	Inventor's Address
1	STREUBER, FRITZ M.	BAKUSBRINK 27, 32120 HIDDENHAUSEN GERMANY

PCT International Classification Number

B32B 3/12

PCT International Application Number

PCT/EP2007/062099

PCT International Filing date

2007-11-08

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA