Thermoplastic honeycomb with improved cell walls, production process and apparatus

Abstract

A folded honeycomb structure is described which is made of a material by plastic deformation perpendicular to the plane of the material, thereby forming semi-hexagonal cell walls and small connecting regions. The cell walls in the L-direction of the honeycomb core have a wave shape with an amplitude of about 10% of the length of the cell walls. The zero slope of the wave shape at the cell wall connections (12, 14, 18, 19) allows optimal shear load transfer between the cell walls. By folding in the conveying direction, the wave-shaped unit walls converge, thereby forming a honeycomb structure.

Description

Technical Field

[0001] The present invention relates to a honeycomb structure such as a folded honeycomb structure, a method for producing the same and an apparatus for producing the same. In particular, the present invention relates to an improved thermoplastic folded honeycomb structure, a process and an apparatus for producing the same. Background Art

[0002] The folded honeycomb known from WO 97 / 03816 is produced continuously from a single layer, for example a flat body. The hexagonal cells are formed by folding after the incisions are introduced. The cells are bridged by connecting the surfaces with a covering layer. By rotary vacuum thermoforming, a folded honeycomb without incisions can be produced economically from a continuous thermoplastic film. Such a folded honeycomb is described in WO 2006 / 053407 and has a connecting surface covering every other hexagonal cell.

[0003] Honeycomb geometries with deformed cell walls have been proposed to facilitate bending of the honeycomb into complex shapes. Wendel's US3991245 shows such aspects: a method for making a flexible honeycomb by corrugation. McCarthy's WO94 / 17993A1 shows such aspects: a method for making a flexible honeycomb by expansion. Hull's WO88 / 06970A1 shows a "formable honeycomb panel" with folds or kinks on the W-cell wall. In addition, honeycombs with folds or kinks in all cell walls have been proposed to increase compressive strength. For example, see "Expanded honeycomb with structural cell walls" WO2014 / 140453A1. Using conventional expansion processes, it has been proposed to include folds in the cell walls before expansion. It is impossible to achieve a specific shape of very thin cell walls based on the width of the cell walls using conventional expansion processes. Summary of the invention

[0004] Embodiments of the present invention provide honeycomb structures, such as folded honeycomb structures, methods of producing the same, and apparatus for producing the same. Specifically, the present invention relates to an improved thermoplastic honeycomb structure, process and apparatus for producing the same.

[0005] The object of the present invention is to be able to provide a honeycomb, such as a folded honeycomb, with improved cell wall geometry, as well as a method and an apparatus for producing such a honeycomb or folded honeycomb.

[0006] The object of the present invention is to be able to provide a honeycomb, such as a folded honeycomb, with a stronger cell wall geometry, as well as a method and an apparatus for producing such a honeycomb or folded honeycomb.

[0007] An advantage of the present invention is that it uses molding techniques such as vacuum forming or rotary vacuum forming. Thermoforming can also be used. These can be used as a step in making the honeycomb core, allowing continuous, cost-effective production.

[0008] An advantage of embodiments of the present invention may be good attachment to the cover layers applied to the honeycomb core. Furthermore, the produced honeycomb product has improved compressibility, allowing for further reduction in material usage.

[0009] Embodiments of the present invention provide a honeycomb that is not made by unfolding or expanding from stacked sheets, such as glued together.

[0010] An embodiment of the present invention provides a honeycomb formed by a plurality of polygonal cells arranged in an array, wherein: each polygonal cell has a lateral cell wall extending between the vertices of each polygonal cell, each polygonal cell is bounded on both sides by a cover layer plane, the lateral cell walls of each polygonal cell form a polygonal ring, and for each polygonal cell, at least one lateral cell wall has a wavy shape, the wavy shape is defined by the deviation from the line connecting two adjacent vertices of a cell, and at the location where the lateral cell wall meets the other lateral cell walls at the connection portion, the slope of the deviation of the lateral cell wall from the wavy shape is zero. The three lateral cell walls are joined together at the vertices (see, for example, Figure 6 ), and the ends of each cell wall meet each other at an angle of 120°, or, for a rectangular cell shape, the four lateral cell walls meet each other at an angle of 90°. Honeycombs with one or more lateral cell walls having a wavy shape have improved mechanical properties. One, some or all of the lateral cell walls of each cell have such a wavy shape. The wavy shape can be included in the honeycomb by the method disclosed in the present application. The wavy shape can be applied to at least one, at least two, at least three or all of the lateral cell walls of each cell, whereby the wavy shape does not have to be the same for all lateral cell walls of a single cell.

[0011] The wavy shape of the lateral cell walls may have four parts: two curved parts in the middle of the wavy shape (i.e., in the middle of the lateral cell walls), the two curved parts deviate from the line connecting two adjacent vertices of a polygonal cell, the two curved parts have an inflection point between them, and each middle part is connected to a tail or end part with a low slope or zero slope. One, some or all of the lateral cell walls of each cell have this wavy shape. The wavy shape can be included in the honeycomb by the method disclosed in the present application. The wavy shape can be applied to at least one, at least two, at least three or all of the lateral cell walls of each cell, whereby the wavy shape does not have to be the same for all lateral cell walls on each cell.

[0012] The wavy shape of the lateral cell wall may have two curved portions, whereby one of the two curved portions is convex and the other is concave, such that the center of curvature of one curved portion is on one side of the lateral cell wall and the center of curvature of the other portion is on the other side of the lateral cell wall.

[0013] The wavy shape of the lateral cell wall may have three parts: a curved part in the middle deviating from a line joining two adjacent vertices of a cell, the middle part connected to two tail or end parts of the lateral cell wall having a low or zero slope.

[0014] At the location where the lateral cell wall with the wave shape meets other lateral cell walls at the connection portion, at the vertex where the deviation of the lateral cell wall is zero, the two tail or end portions have a deviation with a small slope or zero slope.

[0015] The lateral cell walls in the L direction may have a wavy shape and the lateral cell walls in the W direction may have a flat shape, or the lateral cell walls in the L direction may have a wavy shape and the lateral cell walls in the W direction may have a wavy shape.

[0016] A plurality of 3D structures may be formed by plastic deformation of the sheet material, wherein the 3D structures are half cells and folded together and abut or abut against each other to form lateral cell walls of the polygonal cells.

[0017] The wavy shape may have a deviation with an amplitude of 5% to 20%, or in the range of 10% to 15%, of the length of the lateral cell wall between adjacent vertices.

[0018] The polygonal cell may have at least two lateral cell walls forming a double wall having a double material thickness, and both lateral cell walls of the double wall have a wavy shape.

[0019] An embodiment of the present invention provides a method for manufacturing a honeycomb, the method comprising: forming a plurality of polygonal units arranged in an array, each polygonal unit having a lateral unit wall extending between the vertices of each polygonal unit, each polygonal unit being bounded on both sides by a covering layer, the method comprising: forming the lateral unit wall of each polygonal unit into a polygonal ring, and forming at least one lateral unit wall having a wavy shape for each polygonal unit, the wavy shape being defined by the deviation from a line connecting two adjacent vertices of a unit, and at a position where the wavy-shaped lateral unit wall connection portion intersects with other lateral units, the slope of the deviation of the wavy-shaped lateral unit wall is zero.

[0020] The wavy shape of the lateral wall may have four parts: two curved parts in the middle of the wavy shape deviate from the line connecting two adjacent vertices of a polygonal unit, the two middle parts have an inflection point between them, and two tail or end parts with a wavy shape having a low slope or zero slope, wherein one of the two curved parts is convex and one is concave.

[0021] The wavy shape of the lateral cell wall may have three parts: a curved portion which is in the middle of the wavy shape and deviates from a line connecting two adjacent vertices of a polygonal cell, two tail or end portions which have a low slope or zero slope and to which this middle portion is connected.

[0022] The lateral cell walls formed in the L direction may have a wavy shape and the lateral cell walls formed in the W direction may be planar, or the lateral cell walls formed in the L direction may have a wavy shape and the lateral cell walls formed in the W direction may have a wavy shape.

[0023] The wavy shape applied to the lateral cell wall may have a deviating amplitude of 5% to 20%, more precisely in the range of 10% to 15%, of the length of the lateral cell wall between the vertices of the polygonal cells.

[0024] The lateral cell walls with the wave shape can have double material thickness.

[0025] The polygonal cell may have at least one double wall, and two lateral cell walls of the at least one double wall may have a wavy shape.

[0026] An embodiment of the present invention provides an apparatus for manufacturing a honeycomb from a plastically deformable material, the apparatus comprising: a device for forming a plurality of polygonal units arranged in a row, each polygonal unit having a lateral cell wall extending between the vertices of each polygonal unit, each polygonal unit being bounded on both sides by a covering layer plane, a device for forming the lateral cell wall of each polygonal unit into a polygonal ring, and a device for forming at least one lateral cell wall with a wavy shape belonging to the polygonal unit for each polygonal unit, and at least one lateral cell wall is connected or integrated with one or two planar lateral cell walls of the polygonal unit to which it belongs or of an adjacent polygonal unit, and the slope of the lateral cell wall is zero at the position where the lateral cell wall converges to other lateral cell walls at the connection portion.

[0027] The objects of the invention are achieved according to the subject-matter of the attached claims and are further developed by the further features of the dependent claims and by the further aspects described in detail below.

[0028] Further aspects of the invention

[0029] 1. A first aspect of a honeycomb according to the present invention is that it is formed by a plurality of polygonal cells arranged in an array, for example cells arranged in rows and columns, wherein: each polygonal cell has a lateral cell wall extending between the vertices of each polygonal cell, each polygonal cell is bounded on both sides by a cover layer plane, the lateral cell walls of each polygonal cell form a polygonal ring, and for each polygonal cell, at least one lateral cell wall has a wavy shape, the wavy shape being defined by a deviation from a line joining two adjacent vertices of one polygonal cell, and at a location where a lateral cell wall meets other lateral cell walls at a connection portion, the slope of the deviation of the cell wall from the wavy shape is zero.

[0030] Optionally, two or more, or three or more, or four or more, or five or more, or six lateral cell walls of each polygonal cell have a wavy shape.

[0031] For a hexagonal core (see Figure 6 ), the three lateral cell walls join together at an angle of 120° at the vertex, and for rectangular / square cells, the four lateral cell walls meet at an angle of 90° at the vertex.

[0032] The wave shape should preferably be smooth, without kinks or steps.

[0033] 2. Aspect of the honeycomb according to aspect 1, wherein the wavy shape has a sinusoidal, square or triangular cross-section, or has parallel alternating ridges and grooves extending parallel to the longitudinal axis of the honeycomb unit. These wavy shapes are designed to curve generally smoothly without kinks or steps.

[0034] 3. A honeycomb according to aspect 1 or 2, wherein, for each lateral cell wall with a periodic wave shape, the periodic wave shape has a single period for each such lateral cell wall. Optionally, the periodic wave shape has more than one period for each such lateral cell wall, or each lateral cell wall has half a period or more than half a period.

[0035] 4. Aspect of the honeycomb according to any of the preceding aspects, wherein at the vertices of the polygonal cells, where the wavy cell walls meet other lateral cell walls at the junctions, the deviation of the wavy shape is zero.

[0036] 5. An aspect of a honeycomb according to any one of the preceding aspects, wherein the wavy shape of the lateral cell wall has four parts: two curved parts in the middle of the wavy shape deviate from a line connecting two adjacent vertices of a polygonal cell, the two curved parts in the middle have an inflection point between them, and the wavy shape also includes: each curved part having a wavy shape is connected to one of two tail or end parts, and the two tail or end parts have a low slope or zero slope.

[0037] The centres of curvature of the two curved portions are on opposite sides of the lateral cell wall. The arrangement is saddle-shaped.

[0038] The wave shape should preferably be a smooth curve without kinks or steps.

[0039] 6. Aspect of the honeycomb according to aspect 5, wherein one of the two curved portions is convex and one is concave.

[0040] 7. An aspect of a honeycomb according to any one of aspects 1 to 4, wherein the wavy shape of the lateral cell wall has three parts: a curved portion in the middle of the wavy shape, defined by deviation from a line connecting two adjacent vertices of a polygonal cell, and this middle portion is connected to two tail or end portions having a low slope or zero slope.

[0041] The curved portion has no inflection point in the middle of the lateral cell wall.

[0042] 8. An aspect of a honeycomb according to any one of aspects 5 to 7, wherein the end portions have a deviation of low or zero slope at the apex where the deviation is zero, where the wavy cell walls meet the other lateral cell walls at the connection.

[0043] 9. An aspect of a honeycomb according to any one of aspects 5 to 8, wherein at one vertex or at some or each vertex, the deviation of the wavy cell wall is zero and the slope of the wavy cell wall is zero.

[0044] 10. An aspect of a honeycomb according to any one of the preceding aspects, wherein the lateral cell walls in the L direction have a wavy shape and the lateral cell walls in the W direction have a flat shape, or wherein the lateral cell walls in the L direction have a wavy shape and the lateral cell walls in the W direction have a wavy shape.

[0045] 11. Aspect of the honeycomb according to any of the preceding aspects, wherein a plurality of 3D structures are formed by plastic deformation of a sheet material, wherein the 3D structures are half cells and folded together and abut or abut each other to form the lateral cell walls of the polygonal cell. The plastic deformation of the sheet material and the folding together of the half cells to form the final cell results in no need to expand or unfold into stacked strips, such as fixed together by glue. This results in better mechanical properties.

[0046] 12. Aspect of a honeycomb according to any of the preceding aspects, wherein a plurality of polygonal cells are bounded by a cover plane, two open sides towards each polygonal cell, whereby the cells are each fully or partially bridged in one or the other of the cover planes.

[0047] 13. Aspects of a honeycomb according to aspects 11 or 12, wherein the sheet material is one or more sheets of flat bodies, a continuous flat body, multiple sheets of corrugated sheets, a continuous corrugated sheet and / or an uncut or substantially uncut flat body; wherein the multiple 3D structures are formed by plastic deformation of the sheet material.

[0048] 14. An aspect of a honeycomb according to any one of the preceding aspects, wherein the wavy shape has a deviation with an amplitude of 5% to 20%, or in the range of 10% to 15%, of the length of the cell wall between adjacent vertices. The deviation is from a line joining two adjacent vertices of a cell.

[0049] 15. An aspect of a honeycomb according to any of the preceding aspects, wherein at one or some or each vertex the deviation of the wavy cell wall is zero and at one or each vertex the slope of the wavy cell wall is zero.

[0050] 16. Aspect of the honeycomb according to any one of the preceding aspects, wherein at least a portion of each lateral cell wall is permanently connected in whole or in part to another lateral cell wall.

[0051] 17. Aspect of the honeycomb according to any one of aspects 11 to 16, wherein the sheet is formed from a thermoplastic polymer, a fiber composite material or a plastically deformable paper, or the sheet is a metallic sheet. Alternatively, non-metallic sheet materials may be used.

[0052] 18. A honeycomb aspect according to any one of aspects 11 to 17, wherein the sheet is composed of a material selected from the following group, the group including fabrics, spunbond or spunbond laid nonwoven fabrics, meltblown nonwoven fabrics, carded nonwoven fabrics, air laid nonwoven fabrics, wet laid nonwoven fabrics, knitted fabrics, nets, scrims, two-dimensional mats of extruded entangled filaments, consolidated layers of unidirectional fibers, layers of rubber materials, and three-dimensional structural mats of entangled filaments.

[0053] 19. Aspect of the honeycomb according to any of the preceding aspects, wherein at least one side defined by the cover layer plane comprises a cover layer attached to at least one side of the honeycomb.

[0054] 20. Aspect of a honeycomb according to aspect 19, wherein the covering layer is a two-dimensional layer and comprises or consists of a material selected from the following group, the group comprising fabrics, spunbond or spunbond laid nonwoven fabrics, meltblown nonwoven fabrics, carded nonwoven fabrics, air-laid nonwoven fabrics, wet-laid nonwoven fabrics, knitted fabrics, nets, scrims, two-dimensional mats of extruded entangled filaments, consolidated layers of unidirectional fibers, continuous layers, or combinations thereof.

[0055] 21. Aspect of a honeycomb according to any one of aspects 11 to 20, wherein the sheet is composed of a thermoplastic polymer and / or a thermoplastic elastomeric polymer, or a thermoplastic polymer selected from the following group, the group including polyolefins, especially polyethylene or polypropylene; polyesters, especially polyethylene terephthalate; polypropylene terephthalate; polybutylene terephthalate or polyethylene glycol-1,2-furancarboxylate; polyamides, especially polyamide 6 or polyamide 6,6; polycarbonates; polyether ketones; polyether ether ketones; polyether ketone ketones; polyethers; polyether esters; polyphenylene sulfide; polyetherimides; their copolymers and mixtures thereof.

[0056] 22. Aspect of the honeycomb according to any of aspects 11 to 21, further comprising producing a connection region by plastic deformation, the connection region being located in one or other of the cover layer planes of the honeycomb.

[0057] 23. Aspect of the honeycomb according to any of the preceding aspects, wherein the polygonal cells have at least one double material thickness and the two lateral cell walls of the double wall have a wavy shape.

[0058] 24. One aspect of the present invention relates to a method for manufacturing a honeycomb, aspects of which include: forming a plurality of polygonal cells arranged in an array such as rows and columns, each polygonal cell having a lateral cell wall extending between the vertices of each polygonal cell, each polygonal cell being bounded on both sides by a covering layer plane, the lateral cell wall of each polygonal cell being formed as a polygonal ring, and for each polygonal cell, forming at least one lateral cell wall having a wavy shape, the wavy shape being defined by the deviation from a line connecting two adjacent vertices of a cell, and at a position where the lateral cell wall meets other lateral cell walls at a connection portion, the slope of the deviation of the cell wall from the wavy shape is zero.

[0059] The wave shape should preferably be a smooth curve without kinks or steps.

[0060] 25. Aspect of the method according to aspect 24, wherein the wavy shape is formed with a sinusoidal, square or triangular cross-section, or with parallel alternating ridges and grooves extending parallel to the longitudinal axis of the honeycomb cells. The form is generally smooth.

[0061] 26. An aspect of the method according to aspect 24 or 25, wherein the wave shape has four parts: two curved parts in the middle of the wave shape are defined by deviation from a line connecting two adjacent vertices of a polygonal unit, the two middle parts have an inflection point between them, and each curved part is connected to two tail or end parts of the wave shape with low or zero slope, wherein one of the curved parts is convex and one is concave. The centers of curvature of the curved parts are on different sides of the lateral unit wall. The arrangement is saddle-shaped.

[0062] 27. An aspect of the method according to any one of aspects 24 to 25, wherein the wave shape of the cell wall has three parts: a curved part in the middle defined by a deviation from a line connecting two adjacent vertices of a cell, the middle part having two tail or end parts of a wave shape with a low or zero slope, the curved part having no inflection point in the middle. The arrangement is unidirectional.

[0063] 28. Aspect of the method according to aspect 26 or 27, wherein at the location where the lateral wavy cell walls meet other lateral cell walls at the connection portion, the deviation of the wavy shape is zero.

[0064] 29. An aspect of the method according to any of aspects 26 or 28, wherein at one vertex or at some or at each vertex the deviation of the wavy cell wall is zero or the slope of the wavy cell wall is zero.

[0065] 30. An aspect of the method according to any one of aspects 24 to 29, wherein the lateral cell walls formed in the L direction have a wavy shape and the lateral cell walls formed in the W direction are planar, or the lateral cell walls formed in the L direction have a wavy shape and the lateral cell walls formed in the W direction have a wavy shape.

[0066] 31. An aspect of the method according to any one of aspects 24 to 30, comprising forming a plurality of 3D structures by plastic deformation of the sheet material, wherein the 3D structures fold together to abut or abut each other to form a ring of lateral cell walls.

[0067] 32. An aspect of the method according to aspect 31, wherein a plurality of polygonal units are defined by a covering layer plane, two open sides facing each polygonal unit, whereby each unit is fully or partially bridged in one or the other of the covering layer planes, wherein a plurality of 3D structures are formed by plastic deformation of at least some of the sheet material.

[0068] 33. An aspect of the method according to any one of aspects 24 to 32, wherein the wavy shape has a deviation amplitude of 5% to 20%, or in the range of 10% to 15%, of the length of the cell wall between vertices of the polygonal cells.

[0069] The wavy shape is defined by the deviation from a line connecting two adjacent vertices of a cell.

[0070] 34. Aspect of the method according to any of aspects 24 to 33, wherein the lateral cell walls with the periodic wavy shape have double material thickness.

[0071] They can be made of two walls, thus obtaining double thickness.

[0072] 35. An aspect of the method according to any one of aspects 27 to 34, wherein the deviation refers to a plane connecting adjacent vertices of the polygonal unit.

[0073] 36. An aspect of the method according to any one of aspects 31 to 35, wherein the sheet material is one or more flat bodies, a continuous flat body, multiple corrugated sheets, a continuous corrugated sheet, an uncut or substantially uncut flat body; wherein the plurality of 3D structures are formed by plastic deformation of the sheet material.

[0074] 37. Aspect of the method according to any one of aspects 31 to 36, wherein the 3D structure is a region of polygonal shape, sinusoidal shape or arc shape.

[0075] 38. An aspect of the method according to any one of aspects 24 to 37, wherein at least a portion of each lateral cell wall is fully or partially permanently connected to another lateral cell wall.

[0076] 39. An aspect of the method according to any one of aspects 36 to 38, wherein the sheet material comprises multiple flat bodies, a continuous flat body, one or more corrugated sheets, a continuous corrugated sheet, an uncut or substantially uncut flat body; and is formed from a thermoplastic polymer, a fiber composite material, or a plastically deformable paper or metal sheet.

[0077] 40. An aspect of the method according to any one of aspects 36 to 39, wherein the sheet material is made of a material selected from the group consisting of fabrics, spunbonded or spunbonded laid nonwoven fabrics, meltblown nonwoven fabrics, carded nonwoven fabrics, air laid nonwoven fabrics, wet laid nonwoven fabrics, knitted fabrics, nets, scrims, two-dimensional mats of extruded entangled filaments, consolidated layers of unidirectional fibers, layers of rubber material, and three-dimensional structural mats of entangled filaments.

[0078] 41. An aspect of the method according to any one of aspects 24 to 40, wherein at least one side defined by a cover layer plane comprises a cover layer attached to at least one side of the honeycomb.

[0079] 42. An aspect of the method according to aspect 41, wherein the covering layer is a two-dimensional layer and comprises or consists of a material selected from the group consisting of a fabric, a spunbonded or spunbonded laid nonwoven fabric, a meltblown nonwoven fabric, a carded nonwoven fabric, an air-laid nonwoven fabric, a wet-laid nonwoven fabric, a knitted fabric, a net, a scrim, a two-dimensional mat of extruded entangled filaments, a consolidated layer of unidirectional fibers, a continuous layer, or a combination thereof.

[0080] 43. An aspect of the method according to any one of aspects 24 to 42, wherein the sheet is composed of a thermoplastic polymer and / or a thermoplastic elastomeric polymer, or a thermoplastic polymer selected from the following group, the group comprising polyolefins, in particular polyethylene or polypropylene; polyesters, in particular polyethylene terephthalate; polypropylene terephthalate; polybutylene terephthalate or polyethylene glycol-1,2-furancarboxylate; polyamides, in particular polyamide 6 or polyamide 6,6; polyether ketones; polyether ether ketones; polyether ketone ketone polyethers; polyether esters; their copolymers and mixtures thereof.

[0081] 44. An aspect of the method according to any one of aspects 24 to 43, further comprising forming a connection region by plastic deformation, the connection region being located in one or other of the cover layer planes of the honeycomb.

[0082] 45. An aspect of the method according to any one of aspects 24 to 44, wherein the polygonal cell has at least one double lateral cell wall, and two cell walls of the at least one double lateral cell wall have a wavy shape.

[0083] 46. ​​Aspect of the method according to any one of aspects 24 to 45, wherein the plastic deformation is performed by thermoforming, vacuum forming, rotary vacuum thermoforming, or by means of a non-cutting rotary process.

[0084] 47. An aspect of the method according to any one of aspects 31 to 46, wherein the sheet material is cast or extruded as a corrugated sheet and then the corrugated sheet is moulded to modify the corrugations so they form a 3D structure.

[0085] 48. Aspect of the method according to aspect 47, wherein the molding of the corrugations is performed by vacuum molding or thermoforming or by means of a non-cutting rotary process or by means of a rotary vacuum thermoforming process.

[0086] 49. Aspect of the method according to any one of aspects 24 to 48, wherein one, two or more deformed lateral cell walls have a wave shape and optionally have a periodic or cyclic deviation.

[0087] 50. This aspect relates to an apparatus for manufacturing a honeycomb from a plastically deformable material, the apparatus comprising:

[0088] means for forming a plurality of polygonal cells arranged in a row, each polygonal cell having lateral cell walls extending between vertices of each polygonal cell, each polygonal cell being bounded on two sides by a cover layer plane;

[0089] A device for forming the lateral cell wall of each polygonal unit into a polygonal ring, and a device for forming at least one lateral cell wall with a wavy shape belonging to the polygonal unit for each polygonal unit, and at least one lateral cell wall is connected or integrated with one or two planar lateral cell walls of the polygonal unit to which it belongs, or at least one lateral cell wall is connected or integrated with one or two planar lateral cell walls of an adjacent polygonal unit, and the slope of the cell wall is zero at the position where the lateral cell wall intersects with other lateral cell walls at the connecting portion.

[0090] 51. Aspect of the device according to aspect 50, the device comprising

[0091] a) means for plastically deforming the sheet to form therein first 3D structures (1 and 2) and second connection regions (3 and 4), the second connection regions being formed between the first 3D structures and forming at least one wall or at least two walls of the first 3D structures having a wave shape; and

[0092] b) means for folding the first 3D structure towards each other to form cells having cell walls that abut or abut each other in the form of a ring such that a cell wall of one cell abuts a cell wall of another cell in the honeycomb structure;

[0093] c) and forming at least one lateral cell wall having a wave shape for each polygonal cell, and the slope of the wave shape is zero at a position where the at least one lateral cell wall joins other lateral cell walls of each polygonal cell at a connecting portion.

[0094] 52. An aspect of the apparatus according to aspect 50 or 51, comprising an apparatus for processing a flat body into a web, or comprising an apparatus for extruding or casting a flat sheet or web, and subsequently processing the sheet or web using an apparatus for molding at least one cell wall of any polygonal cell to obtain a wavy shape.

[0095] 53. An aspect of the device according to aspect 52, wherein the device for molding is a device for vacuum molding or thermoforming, or a device for a non-cutting rotary process, or a device for a rotary vacuum thermoforming process to form a first 3D structure with at least one cell wall having a wavy shape.

[0096] 54. An aspect of the apparatus according to aspect 52 or 53, wherein the apparatus for casting or extruding a sheet produces a corrugated sheet and further comprises a device for molding the corrugated sheet to modify the corrugations so that they form a first 3D structure having at least one cell wall having a wavy shape.

[0097] 55. An aspect of the apparatus according to any one of aspects 52 to 54, wherein the apparatus for molding is selected from vacuum molding, thermoforming, or an apparatus for a non-cutting rotary process, or an apparatus for a rotary vacuum thermoforming process to form a 3D structure having at least two cell walls or all cell walls having a wavy shape.

[0098] 56. An aspect of the apparatus according to any one of aspects 52 to 55, wherein the apparatus for molding comprises two half-molds, the half-molds having surfaces with a 3D shape, the 3D shape forming a first 3D structure in the sheet, the first 3D structure comprising at least one W-unit wall or at least two unit walls having a wavy shape.

[0099] 57. An aspect of the apparatus according to aspect 56, wherein the mould halves are in the form of matching rotating moulds, or are fixed moulds with upper and lower mould surfaces.

[0100] 58. Aspect of the apparatus according to any one of aspects 51 to 57, further comprising an extruder for extruding the sheet and means for cooling the extruded sheet until it reaches a temperature for molding.

[0101] 59. Aspect of the apparatus according to aspect 58, further comprising means for a further cooling step to solidify the semi-cellular structure into its final shape, and means for folding the semi-cellular structure.

[0102] 60. An aspect of an apparatus configured to produce a honeycomb structure having honeycomb cells from a continuous film or sheet material, wherein the sheet material may be composed of a thermoplastic polymer or a thermoplastic elastomeric polymer, the apparatus being further configured for plastic deformation perpendicular to the plane of the material so as to form a three-dimensional structure and connecting areas, thereby forming semi-hexagonal cell walls, and subsequently, folding the three-dimensional structure toward each other so that the semi-hexagonal cell walls are at a certain angle to each other or adjacent to each other in the form of honeycomb cells, wherein one or more lateral cell walls for each honeycomb cell have a wavy shape. BRIEF DESCRIPTION OF THE DRAWINGS

[0103] The present invention and its exemplary embodiments will be described with reference to the following schematic diagram:

[0104] Figure 1 A cross section of a web of plastically deformed material according to an embodiment of the invention is shown.

[0105] Figure 2 A cross section of a web of material folded in half to form a honeycomb cell is shown in accordance with an embodiment of the present invention.

[0106] Figure 3 An almost completely folded web of material is shown creating two rows of partially enclosed honeycomb cells in accordance with one embodiment of the present invention.

[0107] Figure 4 A side view of a segment of a web of plastically formed material according to an embodiment of the present invention is shown.

[0108] Figure 5 The wavy shape of the cell wall according to an embodiment of the present invention is shown.

[0109] Figure 6 A hexagonal honeycomb pattern with wavy cell walls according to an embodiment of the present invention is shown.

[0110] Figure 7 Variations of cell wall geometries according to embodiments of the invention are shown.

[0111] Figure 8 A view showing a mold surface with a wave shape according to any one of the embodiments of the present invention.

[0112] Fig. 9 A top view of a hexagonal honeycomb core according to an embodiment of the present invention is shown on the left, in which all cell walls have a wavy shape, and a top view of a conventional hexagonal honeycomb for comparison is shown on the right.

[0113] Fig.10 A graph showing the relationship between the flatwise compression strength and density of a conventional hexagonal honeycomb and a hexagonal honeycomb with wavy cell walls according to an embodiment of the present invention is shown.

[0114] Fig.11 Shear buckling failure of a hexagonal honeycomb with wavy cell walls subjected to out-of-plane shear loading in the W direction (WT) is shown.

[0115] Fig.12 A graph showing the relationship between the out-of-plane shear properties of a conventional hexagonal honeycomb and a hexagonal honeycomb with wavy cell walls according to an embodiment of the present invention in the W direction (WT) is shown.

[0116] Fig.13 A hexagonal honeycomb pattern with wavy cell walls according to an embodiment of the present invention is shown, wherein the wavy cell walls have no inflection point in the middle of the cell wall between two vertices.

[0117] This object is achieved according to the subject matter of the attached claims and is further developed by the further features of the dependent claims. DETAILED DESCRIPTION

[0118] definition

[0119] "Wavy shape" refers to the shape of one or more cell walls of the honeycomb core, such as a half-cell that is completely folded from the top down. One or more cell walls of the honeycomb may include one or more cycles or cycles of periodic deviation or cyclic deviation of each lateral cell wall, or half a cycle or multiple half cycles. Alternatively, the wall shape may be a non-cyclic or non-periodic deviation but still provide mechanical properties as good or better than cyclic or periodic deviations. The result of the above deviation is that, for example, for each cell, a wavy cell wall shape is formed in at least one cell wall of the honeycomb cell. The wavy cell wall has a deviation amplitude, which is measured between the adjacent vertices in the reference cell, that is, the straight line / flat plane between the ends of the cell wall with a wavy shape considered. The end edge of the cell wall is at the edge connection to the other cell wall. Preferably, if periodicity or cycle is used, there is a deviation of one and a half cycles, multiple half cycles, one cycle or multiple cycles or cycles between the cell wall connections (i.e., two adjacent vertices) of a polygonal, such as a 4-sided or 6-sided honeycomb cell, along the cell wall connection.

[0120] According to some embodiments, the wavy cell wall shape between the vertices of the honeycomb cell can be described with reference to four parts: after the half-cells have been folded together to make the honeycomb core, the two curved portions in the middle deviate from the plane connecting the two adjacent vertices of a cell. The two intermediate portions have an inflection point between them, and further include two tails or end portions with a low slope or zero slope. One of the curved portions is convex and one is concave. Since the center of the curvature is on opposite sides of the lateral cell wall, the arrangement is saddle-shaped. In other embodiments, the wavy shape of the lateral cell wall has three parts: a curved portion in the middle deviates from the line connecting the two adjacent vertices of a cell, the intermediate portion is connected to two tails or end portions, and the two tails or end portions are connected to one or more other lateral cell walls at the vertex. At the position where the lateral cell wall with a wavy shape converges to other lateral cell walls at the connection portion, at the vertex where the deviation of the lateral cell wall is zero, the end portion preferably has a deviation of zero slope. The end portions are connected to the next cell wall and by doing so they form a vertex and therefore there is zero deviation at this point position. At one vertex or at some vertices or at each vertex of the honeycomb cell, the deviation of the wavy cell wall and the slope of the wavy cell wall are preferably zero.

[0121] Slope

[0122] The slope of a wavy cell wall refers to the slope of the deviation of such a wall. The slope is determined in comparison with a plane joining two adjacent vertices of a polygonal cell. Thus, the slope is the rate of change of the deviation of the lateral cell wall with respect to the distance along the plane joining two adjacent vertices of the polygonal cell. It is preferred if the slope at the vertex is zero. The slope, and in particular the "zero slope", can be determined by reference to Figure 5 and Figure 6 and the descriptive text of these figures. It is preferred if the deviation at the vertex is zero. For what is meant by a small or low slope, see the discussion below on the cell wall shape of the truncated asymptote.

[0123] "L direction or W direction"

[0124] For honeycomb cells made of sheet material with one or more cell walls having double-layer sheet material, the L direction of the honeycomb is the main direction of the double cell walls in such technical honeycombs, while the single cell walls (when present) are at an angle of 30° (alternating positive and negative) to the W direction of the honeycomb and at an angle of 60° to the L direction.

[0125] Vertices at Hub Edges

[0126] The hexagonal or square tubular cell has a plurality of cell walls, whereby one cell wall is connected to another cell wall at a vertex of the hexagonal or rectangular honeycomb cell.

[0127] "Cell wall shape at the cutoff asymptotic portion"

[0128] At each end of the cell wall where one cell wall connects to another cell wall, the shape of the cell wall approaches and preferably reaches a shape of zero slope at the position of zero deviation at each vertex. The approach to the cell wall without a slope can be asymptotically truncated, which reaches zero slope at the vertex because the asymptotic form of the cell wall is truncated. At one vertex or some vertices or each vertex of the honeycomb cell, the deviation of the wavy cell wall and the slope of the wavy cell wall are preferably zero. The end area of ​​the truncated asymptotic portion of the lateral cell wall is preferably limited to the end area of ​​the lateral cell wall at a distance of at most L / 10 or L / 7 from the vertex, where L is the distance between the two vertices of the polygonal cell. In the specification and claims, the slope at the lateral cell wall connection / vertex is described as a low or small slope. In this context, low or small means the shape of the cell wall of the truncated asymptotic portion, which reaches zero slope at a certain distance at the end of the wavy lateral cell wall.

[0129] DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0130] The present invention will be described with reference to specific embodiments and with reference to specific drawings. The drawings are not necessarily drawn to scale, but are schematic and not restrictive. The present invention is more generally defined in the appended claims. Each dependent claim represents a further embodiment of the present invention.

[0131] An embodiment of the present invention provides a honeycomb structure, such as a folded honeycomb structure, formed by a plurality of tubular / cylindrical polygonal units, the tubular / cylindrical polygonal units being arranged in a row and the axes of the tubular / cylindrical polygonal units being parallel to each other - see Fig. 9 . The cells have a polygonal cross-section, such as a quadrilateral (rectangular) or hexagonal (hexagonal) cell, optionally a square. A honeycomb structure, such as a honeycomb core, comprises an array of parallel polygonal cells, each polygonal cell having lateral cell walls, which for each cell are adjacent or abutted to each other in the form of a polygonal ring. The ring can be formed by a plurality of two half cells, which are grouped together, for example, by folding. The rings are formed by cell walls in a polygonal shape; the polygonal shape includes cell walls extending between the vertices of the polygonal shape. The tubular / cylindrical cells can be defined by a cover plane as at least one open side towards each polygonal cell, and optionally towards two open sides of each polygonal cell. The polygonal cells can each be completely or partially bridged in one or the other of the cover planes. A honeycomb, such as a folded honeycomb, can be formed by an uncut or substantially uncut flat body, such as a continuous sheet. A honeycomb, such as a folded honeycomb, is preferably made from a plurality of 3D structures formed by plastic deformation of a sheet. These may have a connection area, for example a connection area produced by plastic deformation of a sheet, which is located in one or the other of the covering layers in the folded honeycomb core. At least one and more preferably two cell walls have a wavy shape, or each of the cell walls of each cell has a wavy shape. The wavy shape refers to the shape of one or more cell walls of the honeycomb core, which deviates from the straight line between two vertices of the honeycomb cell. The shape of the wavy cell wall between the vertices of the honeycomb cell can be described with reference to four parts: two curved parts in the middle of the deviation from the line connecting two adjacent vertices of a cell, the two middle parts having an inflection point between them and two tails or end parts with a low slope or zero slope. One of the curved parts is convex and one is concave. The end part may also have a small or zero slope at the position of zero deviation. At one vertex or at some vertices or at each vertex of the honeycomb cell, the deviation of the wavy cell wall and the slope of the wavy cell wall are preferably zero.

[0132] Each cell may be made of a single thickness of material, i.e. a cell wall of a single sheet material thickness, or the cell may have a cell wall of a single thickness of sheet material and a combination of cell walls of a double thickness of sheet material or of two walls. The cell wall or walls with a wave shape may be a cell wall or walls of a double sheet material thickness.

[0133] Preferably, at least the cell wall which becomes the double cell wall of the honeycomb core in the L direction, for example after the folding step, has a wavy shape. Preferably, each cell wall has a wavy structure.

[0134] The wavy shape of one or more cell walls of the honeycomb unit is a deviation, that is, a deviation in a direction perpendicular to the sheet material of the cell wall, whereby the deviation can be a deviation of at least one, or more than one or all cell walls. This deviation can be semi-periodic or periodic, such as a shape with self-repeating corrugations or sinusoidal deviations. However, non-periodic shapes can be useful and can even be preferred. No matter which type of shape is selected, it should preferably be smooth and continuous, and there should be no steps or kinks. It has been found that the amplitude of the deviation of the wavy cell wall is optimal, for example, in terms of compressive strength, in the distance between vertices, or in the distance between the connection parts to other cell walls, or in the range of 5% to 20% of the length of the cell wall between the cell wall connection parts, more precisely in the range of 10% to 15%. The deviation amplitude of this size helps to prevent or delay the buckling of these cell walls under out-of-plane compression loads. The cell wall is in the form of a corrugated hexagonal (hexagonal) or corrugated quadrilateral (rectangular) tubular honeycomb cell held between one or two covering layers. Even if the wavy cell walls are made slightly thinner to achieve the same density by compensating for their longer length, the flatwise compression strength can be significantly improved. The slope at the beginning and end of the wavy shape, i.e. at or near the vertices of the hexagonal or square cells, i.e. at the cell walls' connection to each other, is preferably small and more precisely zero, so that for hexagonal cells such as hexagonal cells, the cell walls with the wavy shape are connected at the cell wall connection with an angle of 120°, like in a regular hexagonal honeycomb. For quadrilateral cells, optionally rectangular, e.g. square cells, the cell walls are connected at the cell wall connection with an angle of 90°, like in a regular rectangular honeycomb. It has been found that this is important for the out-of-plane shear properties of the honeycomb core. The cell walls have zero deviation at the cell wall connection, i.e. at the vertices of the polygonal form.

[0135] The wavy wall may be formed from four different regions. In the middle of the cell wall, the shape of the wall is curved, the curve defining the deviation. In the middle, there are two curved portions, one convex and one concave, with an inflection point between them. In the end regions, the deviation decreases until the wavy wall shape has zero slope, and preferably reaches zero deviation at the same position.

[0136] A process example

[0137] The production process of folded thermoplastic honeycomb allows the use of a mold for producing a 3D structure in a thermoplastic sheet with a desired geometry to be able to form cell walls by folding. Thermoforming, vacuum forming, rotary vacuum forming or other molding techniques can be used. The input material for molding can be a sheet of material. The process can include a batch process to form the sheet material to be processed, which is then plastically deformed by a molding technique. Heat and pressure can be applied in the mold to plastically deform the sheet material to form a 3D structure with a honeycomb half-cell shape, and some or all of them are wavy cell walls.

[0138] The input material for extrusion can be polymer particles, which can be provided by directly extruding a film from an extruder. The 3D structure can then be directly molded into the extrudate. In another embodiment, preheating and then processing a sheet such as a thermoplastic polymer film to obtain a 3D structure, forming a honeycomb unit when the 3D structure is folded together. The production of the 3D structure can be completed by extruding the sheet and then vacuum forming, rotary vacuum forming, thermoforming.

[0139] Therefore, the 3D structure according to an embodiment of the present invention can be made of a sheet material or foil or film material with a relatively thin cross-section or a small thickness. In terms of wall thickness or cross-section, if the wall thickness is much smaller than the overall size of the structure, such as height or width or length or radius, the structure can be considered to be thin-walled. Compared to the overall size of the structure, the wall thickness can be thinner by one or two orders of magnitude or more. This is related to the thickness of the sheet material and the diameter of the unit. The sheet material can be selected from such a group, that is, the group includes thermoplastic polymers, thermosetting polymers, fabrics, non-woven fabrics such as spunbond bonding or spunbond laying non-woven fabrics, meltblown non-woven fabrics, carded non-woven fabrics, air-laid non-woven fabrics, wet-laid non-woven fabrics, high-loft non-woven fabrics such as V-lap non-woven fabrics including fibers with vertical orientation, knitted fabrics, nets, scrims, two-dimensional mats of extruded entangled filaments, consolidated layers of unidirectional fibers, and rubber layers.

[0140] The woven fabrics, nonwovens, knitted fabrics, nets and scrims may comprise natural fibers such as hemp, jute or flax, mineral fibers such as glass, basalt or rock wool, or fibers made from synthetic polymers.

[0141] Preferably, the films, fabrics, nonwovens, knits, nets and scrims consist of synthetic polymers or mineral fibers, more preferably of thermoplastic polymers and / or thermoplastic elastomeric polymers.

[0142] In a preferred embodiment, the films, fabrics, nonwovens, knitted fabrics, nets and scrims are composed of thermoplastic polymers selected from the group consisting of polyolefins, in particular polyethylene or polypropylene; polyesters, in particular polyethylene terephthalate or recycled polyethylene terephthalate; polypropylene terephthalate; polybutylene terephthalate or polyethylene glycol-1,2-furancarboxylate; polyamides, in particular polyamide 6 or polyamide 6,6; polycarbonates; polyether ketones; polyether ether ketones; polyether ketone ketones; polyethers; polyether esters; polyphenylene sulfide; polyetherimides; copolymers thereof and mixtures thereof.

[0143] Detailed finite element analysis has shown that for out-of-plane compressibility, it is preferred that two or all cell walls in the L direction are wavy, for example with non-periodic or periodic deviations, such as but not limited to sinusoidal, square or triangular cross-sections, for example with parallel ridges and grooves extending parallel to the longitudinal axis of the honeycomb cell, but for out-of-plane shear strength, it is preferred to have very small or zero slope at the connection between the cell walls. The wavy structure may have a periodic structure, and there may be more than one half-cycle or full cycle in one cell wall, but half-cycle or one cycle is preferred. This wavy structure can be defined by the amplitude or deviation of the corrugated waves, the thickness of the sheet and the number of cycles in each wavy cell wall. This wavy structure increases the area moment of inertia. The area moment of inertia or second-order moment of inertia is important in the bending and buckling strength of the honeycomb cell wall. It has been found that the amplitude of the wave structure of the cell walls is optimal in terms of compressive strength, with reference to the straight walls between the ends passing through the cell walls, within the range of 5% to 20% of the length of the cell walls between the connections to other cell walls (which are the vertices of the polygonal form), more precisely within the range of 10% to 15%.

[0144] Surprisingly, if the ends of the wavy cell walls (at the connections to other cell walls) have no slope, the improved compressive strength of the wavy cell walls also results in a higher out-of-plane honeycomb shear strength, so that the adjacent cell walls at the cell wall connections can perfectly support the cell walls. The wavy cell wall pattern according to an embodiment of the present invention can have increased mechanical resistance to early buckling even if the cell walls are thinner to compensate for the greater length of the wavy cell walls. This greatly improves the weight-to-weight compressive strength of the honeycomb.

[0145] The edge support of the wavy L cell wall can be provided by an adjacent cell wall, for example an adjacent cell wall with a smaller deviation amplitude. This support is reduced or significantly reduced if the cell wall in the W direction has a slope at the cell wall connection. When adjacent cell walls are connected with a slope at the cell wall connection, the reduced support of the adjacent cell walls will further reduce the out-of-plane shear stiffness and strength of the honeycomb core. For wavy L cells and wavy W cells, the wall should have a zero slope at the connection to the adjacent cell wall, and the cell wall can approach the connection point as a truncated asymptote that achieves zero deviation and zero slope at the connection point.

[0146] First device embodiment

[0147] Furthermore, the present invention provides a device for producing a folded honeycomb made of a plastically deformable material, the device comprising:

[0148] a) means for plastically deforming the web to form therein a first 3D structure (1 and 2) and a second connection region (3 and 4), the second connection region (3 and 4) being formed between the first 3D structures (1 and 2), wherein at least one wall or at least two walls of the first 3D structures (1 and 2) have a wave shape; and

[0149] b) means for folding the first 3D (1 and 2) structures towards each other to form cells having cell walls that abut or abut each other in the form of a ring such that a cell wall of one cell abuts a cell wall of another cell in the honeycomb structure;

[0150] In order to form the wavy cell walls using a vacuum forming mould, it is necessary to form a small area of ​​attachment at the fold lines 5, 6 between the L cell walls to obtain straight fold lines. Straight fold lines are desirable for a stable folding process.

[0151] The apparatus for producing folded honeycombs can process a flat body into a web. Alternatively, the web can be processed by an apparatus for extruding or casting a flat sheet or web and subsequently processed by an apparatus for molding, such as vacuum molding or thermoforming, or can include a device for a non-cutting rotary process, or by means of a rotary vacuum thermoforming process. Preferably, in an extrusion process, the material is extruded as a film and then directly rotary vacuum thermoformed.

[0152] The sheet can also be cast or extruded as a corrugated sheet, and the corrugated sheet is molded to modify the corrugations so that they form the first 3D structure (1 and 2). This molding can be done by a device for molding, such as vacuum molding or thermoforming, or can include a device for a non-cutting rotary process, or by means of a rotary vacuum thermoforming process, to form a first 3D structure (1 and 2) with at least one cell wall having a wave shape.

[0153] Figure 8 The mold surface that will form the first 3D structure (1 and 2) in the sheet according to an embodiment of the present invention is shown, and all the cell walls have a wavy shape. The molds used for this purpose have formed the geometry of the desired cell walls including the wavy shape in their surfaces. The matching molds may include an upper mold and a lower mold. The molds may be in the form of matching rotating molds, or they may be fixed molds with an upper mold surface and a lower mold surface.

[0154] Embodiments of the present invention may use thermoforming. This is a process in which a thermoplastic sheet is heated to a plastic deformation temperature. The thermoplastic material may be a polymer material.

[0155] Hot sheets in such Figure 8 The cellular core is formed into a specific shape in a mold of the mold shown or in a rotary vacuum forming mold to form at least one or all of the cell walls of the honeycomb core having a wavy shape. The result can be trimmed to cut off excess material. The thermoplastic sheet or web material is preferably heated in an oven to a temperature at which it is ductile so that it can be stretched into or stretched onto a 3D shape in a mold. If extrusion is used, the material will leave the extruder die at a high temperature, and it can be cooled until a temperature at which molding can be performed is reached. The cooling step solidifies the semi-honeycomb structures into their final shape, after which the webs are folded. Embodiments of the present invention may use vacuum forming or rotary vacuum forming, or may use thermoforming, which uses heat and pressure to allow processing of porous materials.

[0156] In thermoforming, a thermoplastic sheet or web may be fed from a roll or extruder and conveyed through an oven to forming temperature.

[0157] In either case, the heated sheet is then moved to a matching set of mold halves. The mold halves are then closed together to deform the thermoplastic sheet into the detailed shape in the mold. After a cooling period, the mold tooling opens and the sheet material is pulled from the mold.

[0158] Second device embodiment

[0159] Furthermore, the invention provides an apparatus for producing a honeycomb, such as a folded honeycomb, from a flat thermoplastic composite sheet or web material consisting of a plastically deformable thermoplastic sheet material. Suitable thermoplastic materials may be selected from the polymer materials mentioned above.

[0160] The equipment may include:

[0161] Device for delivering a flat or corrugated thermoplastic composite sheet from a roll, or for extruding a flat or corrugated sheet from an extruder, or for taking out a flat or corrugated sheet from a stack of sheets,

[0162] b) means for plastically deforming a flat thermoplastic sheet material to form or complete therein a first 3D structure (1 and 2) and a second connection area (3 and 4), the second connection area (3 and 4) being formed between the first 3D structures (1 and 2), at least one or at least two of the walls of the first 3D structures (1 and 2) having a wavy shape; and

[0163] c) means for folding the first 3D (1 and 2) structures towards each other to form cells having cell walls that abut each other in the form of a ring such that a cell wall of one cell abuts a cell wall of another cell in the honeycomb structure;

[0164] In an embodiment of the invention, the final honeycomb may have closed ends for the cells. Preferably, only half of the cells are closed at the ends. Figure 1 A cross section of a flat web of a thermoplastic polymer, for example a thin, plastically deformable material, is shown, having plastically deformed portions formed in the composite material perpendicular to the web or sheet of material. In the region of the first 3D structures 1 and 2, the material is formed from a planar polygon of the web, such as a trapezoidal, sinusoidal, arcuate, etc. Since the folding lines 5 and 6 remain in the plane of the web, the material is stretched and second connection areas 3 and 4 are formed, which are essentially perpendicular to the web of material. The deformation of the thermoplastic composite web material in the various regions causes deformation of the first three-dimensional shape or structure 1 and 2, which forms the walls of the cell halves in the folded finished product. In addition, molding produces one or more walls of plastically deformed material, which walls will become the cell walls in the final honeycomb core and have a wavy shape. These cell walls with a wavy shape will be, for example, cell walls in the final product, which has walls with double material thickness. For example in Figure 1 In the embodiment, the walls 10 will abut against each other to form a cell wall with a double thickness of the honeycomb. Figure 1 As shown, the first 3D structures 1 and 2 are elongated. The waves of the wall have a wave shape with grooves and ridges running along the long sides of the first 3D structures 1 and 2. This will improve the compressive strength when force is applied in the thickness direction of the final honeycomb core.

[0165] The cells with wavy cell walls are structural and load-bearing elements of the foldable finished product, whose walls extend transversely to the longitudinal direction of the foldable finished product. In the foldable finished product, the cells formed by folding preferably have a cylindrical cross section, the axis of the cylinder extending transversely to the longitudinal direction of the foldable finished product. The cross-sectional shape of the cells is formed flat or wavy and can be selected as desired, for example circular or polygonal, in particular even-numbered polygonal, such as hexagonal.

[0166] Figure 2 A further intermediate state in the production of a folded honeycomb is shown. The narrowing of the deformed material web occurs by a folding operation of the material web around the folding lines 5 and 6. By means of this folding operation, the second connection areas 3 and 4 come to lie flat in the upper and lower surface planes of the honeycomb core. The folding operation can be accomplished by a compressive force which compacts the web in the production direction. Expansion deformations of the cell walls transversely to the production direction are avoided by the second connection areas 3 and 4. The folding operation can also be carried out, for example, by means of a hot tool, which can also preheat the cell walls which meet each other for bonding, for example with an adhesive or by welding, such as ultrasonic welding.

[0167] Figure 1 and Figure 2 A cross section of a flat sheet or web made of a plastically deformable material is shown. The plastically deformable material may be a thermoplastic polymer material, or a fiber composite material or the like. According to this embodiment, the flat web or sheet has a plastic deformation portion, which is mainly perpendicular to the material web, forming the first 3D structures 1 and 2 therein. In the region of the first 3D structures 1 and 2, the material is deformed from the plane of the web, for example, polygonally, such as a trapezoid, a sinusoid, an arcuate, etc. The deformation portion forms a ridge 8 and a valley 9, whereby each of these ridges and valleys is discontinuous. For example, the ridge 8 is composed of a series of linear deformation segments, such as the first 3D structures 1 and 2, such as polygons, such as trapezoidal, sinusoidal, or arcuate portions, etc. Preferably, the ridge 8 has a top surface 10, which may be initially (e.g., as formed) parallel to the plane of the web of the material. When the first 3D structures 1 and 2 are rotated (also referred to as "folded") to form a honeycomb unit, the two top surfaces 10 will abut against each other. At least the cell walls with double material thickness will have an undulating shape. The undulating shape is a corrugated shape that deviates periodically from the plane of the surface 10, with the corrugated shape having a periodic deviation perpendicular to the plane of the surface 10. Figure 1 The ridges 8 and valleys 9 extend across the surface 10 in the direction of production as shown. Preferably the wave pattern has only one period, but half a period or a plurality of half periods or a plurality of full periods are included within the scope of the invention.

[0168] The production direction is preferably as follows Figure 1 However, directions perpendicular thereto (parallel to the axes or fold lines 5 and 6) may also be used.

[0169] The area comprising the first 3D structures 1 and 2 is preferably formed to be inclined, i.e. rotated towards each other around an axis or folding line 5 and / or 6 to form a further u-shaped or v-shaped second connection area 3 and 4. The second connection areas 3 and 4 separate the ridges of the first 3D structures 1 and 2 in a row of areas comprising the first 3D structures 1 and 2, such as polygons, such as trapezoidal, sinusoidal or curved segments, etc. One second connection area 3, 4 is placed between two areas comprising the first 3D structures 1, 2, and the second connection areas 3 alternate along the rows of areas comprising the first 3D structures 1, 2 and the second connection areas 4. The second connection areas 3, 4 are formed to cross the valleys, i.e. perpendicular to the valleys 9. Adjacent cross valleys are on opposite sides of the web material. Preferably, the rotation of the area comprising the first 3D structures 1, 2 is to bring them to the same position. Figure 1 This rotation of the initial position preferably simultaneously places a deformation into the web of the material. The web material is stretched at the transition between the areas comprising the first 3D structures 1 and 2 to form second connection areas 3 and 4, which are substantially perpendicular to the outer surface of the areas comprising the first 3D structures 1 and 2. The angle between the top surfaces of the second connection areas 3, 4 on the different ridges 8 allows a part of the tool to enter, so as to form these ridges 8. The width direction of the web of material is preferably parallel to the direction of the axes 5 and 6, while the endless length direction of the web of material is continuous along the production direction (shown in Figure 1 between line 7 in the figure).

[0170] The deformation of the web or sheet material results in the formation of three-dimensional shapes or structures 1 and 2, which form the walls of the cell halves in the folded finished product. The cells thus formed are structural and load-bearing elements of the folded finished product, whose walls extend transversely to the longitudinal direction of the folded finished product. The cell walls with a wavy shape contribute to improving the out-of-plane compressive strength. In the final folded product, the cells formed by folding preferably have a cylindrical cross-section, the axis of the cylinder extending transversely to the longitudinal direction of the folded finished product and extending in the thickness direction of the planar honeycomb finally produced. The basic cross-sectional shape of the cell can be selected as desired, for example circular or polygonal, in particular even-numbered polygons, such as hexagons. This cross-section is modified by forming at least one or at least two cell walls, for example these cell walls have double material thickness. The final cell shape depends on the shape of the deformed areas including the 3D structures 1, 2 in the initial web and how they are folded together. As Figure 3As shown, when the web is almost completely folded, each cell is formed by two half-cells. These cells are arranged in rows. Each final cell is formed by the bottom and edge of two longitudinally adjacent (in the sheet or web material) valleys 9. The half-cells are preferably connected together across the contact surface 10 from two longitudinally adjacent (in the web material) ridges 8. Therefore, the present invention provides a folded honeycomb, which is formed by a plurality of cells arranged in rows, with the following characteristics: the cells have lateral cell walls, which are adjacent to each other in the form of rings and are bounded by the cover layer plane towards the two open sides of the cell, whereby each cell is bridged or completely closed in one or the other of the cover layer planes. At least one or at least two cell walls have a wavy shape. The cell wall with double material thickness preferably has a wavy shape. The folded honeycomb can be formed by a substantially uncut flat body, i.e. a non-porous continuous sheet. The sheet can be extruded and can be extruded with corrugations. The plastic deformation of the sheet or corrugated sheet forms a 3D structure. Thus, the folded honeycomb comprises a plurality of 3D structures 1 and 2, such as polygonal, sinusoidal or curved shaped areas formed by plastic deformation, and second connection areas 3 and 4 in the cover plane produced by plastic deformation. At least a portion of the cell walls are preferably fully or partially permanently connected to each other, such as by glue or adhesive or welding. Preferably, the portions of the cell walls close to the two cover planes are welded together. In a double belt laminator, this can be done by heating the honeycomb core surface, preferably while welding the cover sheet to the honeycomb core.

[0171] The invention includes a final folded product which is a mixture of cells with different cross-sectional shapes and / or sizes. In particular, at least one cell wall or at least two cell walls have a wavy shape.

[0172] The final honeycomb structure is a planar product whereby the cells are arranged perpendicular to the plane of the product and across the thickness. The cells on alternating sides of the planar structure are closed by connecting areas 3, 4. All cells can be closed by applying one or more covering layers, for example by laminating the planar product of the invention with a covering sheet. The invention includes within its scope the possibility that the first 3D structure 1, 2, for example a trapezoidal, sinusoidal or circular structure in the web, after folding of the deformed material web, forms a structure in which the cell walls are not completely vertical and / or do not touch each other, thus forming a structure which is open in at least one direction in the plane (e.g. Figure 3 shown).

[0173] Returning to the production side of the method and Figure 4 The production aspect of the method continues with the step of further rotating the regions 1 and 2 such that the surfaces 10 of adjacent ridges 8 are adjacent to or preferably in contact with each other. Figure 4A side view of an intermediate state during the production of a folded honeycomb is shown. The narrowing of the plastically deformed material web occurs by a folding operation of the material web around axes or folding lines 5 and 6. The U-shaped or V-shaped connecting areas 3 and 4 are developed in a plane perpendicular to the cell walls and lie flat. The connecting areas 3 and 4 are introduced to avoid significant deformation of the 3D structures 1 and 2 of the material web, for example polygons such as trapezoids, or sinusoidal or arcuate deformation sections, etc.

[0174] Figure 3 The material is shown almost completely folded to form two rows of hexagonal honeycomb cells. As a result of the folding together, adjacent connection areas 3 (respectively 4) abut against each other. Subsequently, each honeycomb cell is closed at least on one side by a connection area 3 or 4. That is, the cell has a closed surface formed by the connection areas 3, 4 on one end. The surfaces 10 can be connected to each other, for example using glue or adhesive or by welding, such as ultrasonic welding. Preferably, at least the edges of the surfaces 10 connected to the connection areas 3 and 4 are connected to each other. However, this connection is not a necessary requirement of the present invention.

[0175] The above process relies on folding a deformed web material, thereby completing the method of forming the 3D structure 1, 2 and the surfaces 3, 4 to simplify the folding and rotating process. Figure 4 A side view of the formed material web prior to the folding operation is shown. To facilitate the folding operation, the plastically deformed material web has axes or fold lines 5 and 6 (about which the material area comprising the 3D structures 1 and 2 rotates during folding) preferably positioned out of the plane with a positive value "x". The dimension x is chosen so that the lowest apex connection point on the axis 6 through the valley on the upper surface of the material is higher than the apex connection point on the lower surface of the web through the valley on the axis 5. Longitudinal forces in the production direction will act through the axes 5 and 6 and by doing so will apply bending moments about the axes 5, 6. This allows the formed material web to be folded up by simple compression in the production direction.

[0176] Production can be run discontinuously, for example using a static mold, or can be automated and run continuously. Preferably, pairs of rollers are used to push the material web or sheet together in the production direction. However, a rotating tool, an oscillating translation tool or a guiding profile can be used to facilitate or ensure the folding of the web or sheet. Therefore, an independent aspect of the present invention is to form a folded honeycomb by means of non-cutting, continuous, static plastic non-rotational or plastic rotational formation of the material web. Plastic deformation can be carried out, for example, by means of rotary vacuum thermoforming or rotary thermoforming without vacuum or a static molding process. The sheet or web material can be provided as a stacked film, either from a roller, or via a film from a die of an extruder. The mold has mutually engaging profiles, for example on each of the two mold surfaces, or on rollers that travel against each other.

[0177] The surface of the die or roller, e.g. vacuum roller, used for thermoforming of the material sheet or web has a relatively complex geometry so that the regions 1 and 2 in the formed material web can not only be formed but also preferably only slightly rotated towards each other (e.g. 10° to 30°). This allows the formation of the V-shaped connecting regions 3 and 4 and ensures a vacuum thermoformable, airtight shape of the material web, which can be folded by further rotation of the regions 1 and 2 about the axes 5 and 6 (e.g. about 80° to 60°).

[0178] The folding apparatus may comprise a pair of feed rollers with grooves in the surface, such as rubber coated feed rollers, placed upstream of the guide grid to keep the material web in a plane during folding, and a second set of rollers with similar grooves, such as rubber coated push rollers, to apply a counter pressure, which ensures sufficient in-plane compressive force to achieve folding. The compressive force between the lower and upper feed rollers can be reduced by elastic deformation of the tilting and rotation of the regions 1 and 2 towards each other, but in the section between the feed rollers and the counter rollers, the material web will preferably but not necessarily move back into its thermoformed shape without the help of tools or guides and continue to fold up. The gating and / or braking mechanism initially slows or stops the web. It opens under a force that can only be generated by the material web in the fully folded stage. As the folded web is formed, it continues to apply friction in its open state.

[0179] The folded honeycomb is preferably directly further processed into a lightweight sandwich panel by laminating or extruding cover layers onto both sides of the honeycomb core, for example using laminating rollers or belts. The apparatus provided by the invention may comprise a deforming and folding unit as well as a core gluing or welding unit and a laminating unit.

[0180] The web sheet material can be provided directly from a suitable forming device, such as an extruder, or from a roll of web material or a stacked sheet material. Optionally, the web or material sheet is maintained at a certain temperature or heated to a forming temperature. The 3D structures 1, 2 are formed in the web material or sheet material by any suitable process, such as thermoforming, vacuum forming or hot rolling. Instead of using vacuum forming, molding including pressure plates of opposite shapes can be used to apply pressure and heat to forgeable (e.g., hot) thermoplastic sheets to form half units. This allows the use of perforated materials, which would be impossible if vacuum forming was applied. Perforations can be produced while applying pressure, or can be made into the sheet before the pressure molding step. In space applications, making honeycomb cores from self-perforated sheets can help reduce noise or ensure ventilation of the honeycomb units.

[0181] The web material formed with the 3D structure is folded together to form the honeycomb core. Optionally, lamination of one or more cover layers or other layers is performed in-line or off-line. Finally, post-forming operations are performed, such as cutting to length or forming the honeycomb material into shape, for example by pressing or fixing the honeycomb material to another, such as a metal part.

[0182] The invention comprises a folded honeycomb where the connecting areas 3 and 4 are removed later, for example during lamination of the nonwoven cover layer, for example by cutting or melting, so that all cells are open on both sides. Folded honeycombs made from thermoplastic materials can be formed well into complex 3D shapes after preheating of the material. The wavy cell walls are easy to form into complex 3D shapes without preheating of the material.

[0183] Depending on the raw materials used for the folded honeycomb core and the covering layers, the sandwich panels can be used, for example, for structural components, impact and crash protection, decorative panels or packaging applications.

[0184] Figures 5 to 7 Various variations of wavy cell walls are shown. These can be used with any of the embodiments described above.

[0185] Figure 5 Shows Figure 61 is a top view of a periodic shape marked as 11 in FIG. A single period is shown, which is preferred, but more than one period can be used, for example for larger honeycomb cores. Preferably, at least such cell walls (for example after a folding step) have a wavy shape, i.e. the cell walls become double material thickness in the L direction of the honeycomb core. The wavy shape, for example the wavy shape for the cell walls with double material thickness, has a deviation with an amplitude in the range of 5% to 20%, more precisely in the range of 10% to 15%, of the distance between the vertices of a polygonal cell (for example a hexagon or an elongated rectangle or a square, or a quadrilateral or a hexagon) or the length of the cell wall with double material thickness between the vertices. The other cell walls are single cell walls of the honeycomb core in the W direction. The wavy shape of these cell walls can have a smaller amplitude but can also have the same amplitude as the wavy shape of the double cell walls. The periodic shape used in any embodiment of the present invention has a slope at the beginning and end of the wave shape, i.e. at the edge of the cell wall, which is preferably small and more precisely zero, so that for hexagonal cells, the cell walls are connected at a 120° angle (2 times 60°) at the cell wall connection, like in a regular hexagonal honeycomb. For long rectangular or square cells, the cell walls are connected at a 90° angle at the cell wall connection, like in a regular rectangular honeycomb.

[0186] Figure 6 A further example is shown, which shows a top view of a cell having a hexagonal, eg honeycomb core, which may be used with any embodiment of the invention providing a honeycomb core. Figure 6 A cell geometry is shown where each cell wall 11, 16, 17 has a wave shape with a single period between the vertices (at least 18, 12, 14, 19) of the hexagon. Included in the present invention are multiple periods for the lateral cell walls, or multiple half periods for each lateral cell wall. The wave shape is joined at the cell wall joints (at least at the vertices 18, 12, 14, 19) where there is no slope, so that the orientation of the cell walls at the joints is consistent with the overall direction of the cell walls. Thus, the cell walls are joined at an angle of 120°, as shown at vertex 12 (for rectangular cells, the angle is 90°). Figure 6 It is shown that all cell walls have a wavy shape. Figure 6 The cells in may include rectangular, for example, square honeycomb cells. Figure 6The wavy shape for the cell walls may have a single thickness, but in the case of one or more cell walls with double material thickness. The wavy shape has a deviation, the deviation has an amplitude, the amplitude is in the range of 5% to 20% of the distance between the vertices, more precisely in the range of 10% to 15% of the distance between the vertices, like at least 18, 12, 14, 19 of a polygonal cell (e.g., hexagonal or long rectangle or square, or quadrilateral or hexagonal), or the length of the cell wall with double material thickness between the vertices. The other cell walls are single cell walls of the honeycomb core in the W direction. The wavy shape of these cell walls may have a smaller amplitude, or the same amplitude as the wavy shape of the double cell wall. The periodic shape used in any embodiment of the present invention has a slope at the beginning and end of the wavy shape, that is, at the edge of the cell wall, the slope is preferably small and more precisely zero, so that for a hexagonal cell, the cell wall is connected at an angle of 120° at the cell wall connection, like in a regular hexagonal honeycomb. For long rectangular or square cells, the cell walls are joined at 90° angles at the cell wall connections, like in a regular rectangular honeycomb.

[0187] Figure 7 A single cycle of a wave shape 50 is shown, which schematically illustrates different options for the shape of the wave-shaped cell wall. The cell wall shape 50 includes four portions of the cell wall, all of which are made of sheet material and integrally together as the cell wall. Portions 54 and 56 are convex / concave curved regions of the cell wall (convex in opposite directions), which are connected together, for example, integral with each other, and pass through the inflection point 51 between them at the zero deviation point. Alternatively, portions 54 and 56 may form a single convex / concave curved region without an inflection point. These curved regions 54, 56 may be the same corresponding sinusoidal shape or pseudo-sinusoidal shape. The curved region 56 includes a position 55 (convex in opposite directions) having the maximum deviation in the cell wall in one direction. Figure 7 The curved region 54 includes a position 53 ( Figure 7 57 in the figure). On the edge away from region 56, there is a tail region 52. The tail region 52 is connected to the next cell wall at the connection point or vertex of the honeycomb (not shown), and its slope is less than the slope of the corresponding sinusoidal shape at this position, or its shape is a truncated asymptote that reaches zero slope at the wavy cell wall. The slope can be monotonically non-increasing until it reaches zero slope.

[0188] On the edge away from the portion 54, there is a tail region 58. The tail region 58 is connected to the next cell wall at the connection point or vertex of the honeycomb core (not shown), and its slope is less than the slope of the corresponding sinusoidal shape at this point, or its shape is a truncated asymptote reaching a zero slope, or the slope of the wavy cell wall of the tail region 52 is zero, or the wavy cell wall is monotonically non-increasing until it reaches a zero slope.

[0189] The small slope or preferably zero slope of the wave shape at the cell wall connection ( Figure 7 The solid line 57 in FIG. 5 is shown as being opposite to a wave shape having a clear slope, or even a maximum slope at the cell wall connection ( Figure 7 The wave shapes associated with the two materials may be slightly different.

[0190] Figure 8 A mold surface for vacuum forming of a web with wavy cell walls is shown. Other molding aspects of the method may be used, such as pressure and heat using a mold with top and bottom presses. The formation of the wavy L cell walls results in the formation of small additional skin connection areas 30 and 40 at the fold lines. This allows for a simple and reliable folding operation at straight fold lines. Smaller additional skin connection areas 30 and 40 can improve the core skin connection at the L cell walls.

[0191] Fig. 9 A top view of a folded honeycomb with wavy cell walls is shown on the left side of the page, and a top view of a conventional hexagonal honeycomb with straight cell walls is shown on the right side of the page.

[0192] Fig.10 The relationship between the planar compressive strength and the density of the honeycomb cell wall is shown. The results of the compression test on the honeycomb with wavy cell walls are that the density ranges from 60-70 kg / m 3 , about 70% higher. Compared with conventional hexagonal honeycombs with flat and straight cell walls, the density range is 80-90kg / m 3 The compressive strength is about 49% higher and the density is in the range of 110-120kg / m 3 The compressive strength is about 23% higher when the wavy cell wall geometry allows a density reduction of about 20 kg / m at a lower density at the same compressive strength. 3 This can lead to significant savings in raw material costs and resources. For the properties of sandwich core materials, in addition to out-of-plane compressive stiffness and strength, out-of-plane shear stiffness and strength are also crucial.

[0193] Fig.11The shear buckling failure mode of a honeycomb core with wavy cell walls subjected to out-of-plane shear loading in the W direction is shown. Due to the double L cell walls, the out-of-plane shear strength in the W direction in technical honeycomb cores is usually significantly lower than in the L direction.

[0194] Fig.12 A comparison of stress-strain curves of honeycomb cores with and without wavy cell walls of the same density subjected to out-of-plane shear loads in the W direction obtained by FEM analysis is shown. The shear stiffness of the wavy cell wall honeycomb is almost equal to that of a conventional honeycomb with straight cell walls, but the performance of the honeycomb with wavy cell walls is significantly better in terms of shear strength. Without being limited by theory, the higher shear strength is believed to be due to the later onset of shear buckling of the wavy W cell walls. This effect was also found in the L direction, but there was less increase in the already very good shear strength in this direction. Together this leads to a more balanced shear performance in the two main directions of the honeycomb core. If desired, a further balance of equal shear properties in both directions can be achieved by reducing the length of the L cell wall compared to the length of the W cell wall.

[0195] Fig.13 A further embodiment of the invention is shown, which can be made from any of the devices of the invention, and can be made from any of the disclosed materials, and can be used in any of the product embodiments of the invention. Figure 6 The wavy cell walls are different. Fig.13 The cell walls in the LASER have no inflection point in the middle of the cell wall. In contrast, there is a predominantly curved shape for the lateral cell walls. Depending on which lateral cell wall is involved, the concave or convex surface for the lateral cell wall points to the center of the cell. Fig.13 shows a hexagonal cell with all lateral cell walls having a wavy shape. If the cell is rotated through 120°, Fig.13 The wavy shape of the lateral cell walls shown will be maintained, but not if the cell is rotated through 60°. In the case of a rectangular, e.g. square, honeycomb cell type, this angle is 180°. Fig.13 The wavy cell walls in the can be translated to the opposite side of the honeycomb cell while maintaining the same shape. Fig.13 The wave shape can be a periodic shape, whereby Fig.13 Each lateral cell wall has one and a half period, ie the center of curvature is on one side of the lateral cell wall. Also included within the scope of the invention are 1.5, 2.5, etc. periods per lateral cell wall.

[0196] In contrast, Figure 6A wavy curved shape applied to the lateral cell walls is shown, the wavy shape having a concave and convex shape for each lateral cell wall, thus showing the center of curvature of the lateral cell walls on different sides and the inflection points in the wavy shape. If the lateral cell walls are rotated through 60°, the wavy shape of one lateral cell wall will be maintained. In the case of a rectangular, e.g. square, honeycomb cell type, this angle is 90°. The wavy cell wall can be translated to the opposite side of the honeycomb cell while maintaining the same shape. Figure 6 The wave shape can be a periodic shape, whereby in Figure 16 there is one period for each lateral cell wall. Also included within the scope of the invention is 2, 3, etc. periods for each lateral cell wall. Also included within the scope of the invention is 2, 3, etc. periods for each lateral cell wall.

[0197] refer to Figure 6 and 13 , all lateral cell walls are shown with a wave shape. Also included in the present invention is at least one, at least two, at least three or all lateral cell walls of a cell having a wave shape. The wave shape of different lateral cell walls of a cell may be different. This can be achieved by using the molding technology disclosed in the embodiments of the present invention.

Claims

1. A honeycomb formed by a plurality of polygonal cells arranged in an array, wherein: Each of the polygonal units has a lateral unit wall extending between the vertices of each of the polygonal units, each of the polygonal units is bounded on both sides by a covering layer plane, the lateral unit walls of each of the polygonal units form a polygonal ring, and for each of the polygonal units, at least one of the lateral unit walls has a wavy shape, the wavy shape is defined by the deviation from the line connecting two adjacent vertices of one of the polygonal units, and at the position where the lateral unit wall meets the other lateral unit walls at the connecting portion, the slope of the deviation of the lateral unit wall from the wavy shape is zero.

2. The honeycomb according to claim 1, characterized in that The honeycomb includes two or more, or three or more, or four or more, or five or more, or six lateral cell walls per polygonal cell having a wavy shape.

3. The honeycomb according to claim 1, characterized in that: For a hexagonal core, three of the lateral cell walls join together at an angle of 120° at a vertex, or wherein for a rectangular / square cell, four of the lateral cell walls meet at an angle of 90° at a vertex.

4. A honeycomb according to any one of the preceding claims, characterised in that The wave shape is a smooth curve without kinks or steps.

5. The honeycomb according to claim 1, characterized in that: The wavy shape has a sinusoidal, square or triangular cross-section, or wherein the wavy shape has parallel alternating ridges and grooves extending parallel to the longitudinal axis of the polygonal honeycomb cell.

6. The honeycomb according to claim 1 or 2, characterized in that: For each of the lateral cell walls having a periodic wave shape, the periodic wave shape has a single period for each of the lateral cell walls, or the periodic wave shape has more than one period for each of the lateral cell walls, or each of the lateral cell walls has half a period or more than half a period.

7. A honeycomb according to any one of the preceding claims, characterised in that At the vertices of the polygonal cells, where the wavy cell walls meet other lateral cell walls at the connection, the deviation of the wavy shape is zero.

8. A honeycomb according to any one of the preceding claims, characterised in that The wavy shape of the lateral cell wall has four parts: two curved portions in the middle of the wavy shape, and wherein the two curved portions deviate from a line connecting two adjacent vertices of a polygonal cell, the two curved portions have an inflection point between them, and wherein each curved portion in the middle is connected to a tail or end portion with a low slope or zero slope.

9. The honeycomb according to claim 8, characterized in that The centers of curvature of the two curved portions are on opposite sides of the lateral cell wall.

10. The honeycomb according to claim 8 or 9, characterized in that: The wave shape is saddle-shaped and has no kinks or steps.

11. The honeycomb according to any one of claims 8 to 10, characterized in that One of the two curved portions in the middle of the wave shape is convex and the other of the two curved portions is concave, so that the center of curvature of one curved portion is on one side of the lateral cell wall and the center of curvature of the other curved portion is on the other side of the lateral cell wall.

12. The honeycomb according to any one of claims 1 to 10, characterized in that The wavy shape of the lateral cell wall has three parts: a curved part in the middle deviates from a line connecting two adjacent vertices of a polygonal cell, and the middle part is connected to two tail or end parts of the lateral cell wall with low or zero slope.

13. The honeycomb according to any one of claims 8 to 12, characterized in that At the position where the lateral cell wall having a wave shape meets other lateral cell walls at the connection portion, at the vertices of the polygonal unit where the deviation of the lateral cell wall is zero, the two tail or end portions have a low slope or zero slope.

14. A honeycomb according to any one of the preceding claims, characterised in that The lateral cell wall in the L direction has a wavy shape and the lateral cell wall in the W direction has a flat shape, or wherein the lateral cell wall in the L direction has a wavy shape and the lateral cell wall in the W direction has a wavy shape.

15. A honeycomb according to any one of the preceding claims, characterised in that A plurality of 3D structures are formed by plastic deformation of a sheet material, wherein the 3D structures are half cells and are folded together and abut or abut each other to form the lateral cell walls of the polygonal cells.

16. A honeycomb according to any one of the preceding claims, characterised in that A plurality of the polygonal units are bounded by a cover layer plane, two open sides towards each of the polygonal units, whereby each of the polygonal units fully or partially bridges in one of the cover layer planes.

17. The honeycomb according to any one of claims 15 to 16, characterized in that The sheet material is one or more sheets of flat bodies, a continuous flat body, multiple sheets of corrugated sheets, a continuous corrugated sheet and / or an uncut or substantially uncut flat body; wherein the plurality of 3D structures are formed by plastic deformation of the sheet material.

18. A honeycomb according to any one of the preceding claims, characterised in that The wavy shape has a deviation with an amplitude of 5% to 20%, or in the range of 10% to 15%, of the length of the lateral cell wall between adjacent vertices.

19. A honeycomb according to any one of the preceding claims, characterised in that At one or some or each vertex, the deviation of the wavy cell wall is zero, and at one or each vertex, the slope of the wavy cell wall is zero.

20. A honeycomb according to any one of the preceding claims, characterised in that At least a portion of each of the lateral cell walls is fully or partially permanently connected to another of the lateral cell walls.

21. A honeycomb according to any one of the preceding claims 15 to 20, characterised in that The sheet material is formed from a thermoplastic polymer, a fiber composite material or a plastically deformable paper, or the sheet material is a metallic sheet or a non-metallic sheet.

22. A honeycomb according to any one of claims 15 to 21, characterized in that The sheet is composed of a material selected from the following group, the group including fabrics, spunbond or spunbond laid nonwoven fabrics, meltblown nonwoven fabrics, carded nonwoven fabrics, air-laid nonwoven fabrics, wet-laid nonwoven fabrics, knitted fabrics, nets, scrims, two-dimensional mats of extruded entangled filaments, consolidated layers of unidirectional fibers, layers of rubber materials, and three-dimensional structural mats of entangled filaments.

23. A honeycomb according to any one of the preceding claims, characterised in that At least one side defined by the cover layer plane includes the cover layer attached to the at least one side.

24. The honeycomb according to claim 23, characterized in that The cover layer is a two-dimensional layer and comprises or consists of a material selected from the group consisting of a fabric, a spunbonded or spunbonded laid nonwoven, a meltblown nonwoven, a carded nonwoven, an air-laid nonwoven, a wet-laid nonwoven, a knitted fabric, a net, a scrim, a two-dimensional mat of extruded entangled filaments, a consolidated layer of unidirectional fibers, a continuous layer, or a combination thereof.

25. A honeycomb according to any one of claims 15 to 24, characterized in that The sheet is composed of a thermoplastic polymer and / or a thermoplastic elastomeric polymer, or a thermoplastic polymer selected from the following group, the group including polyolefins, especially polyethylene or polypropylene; polyesters, especially polyethylene terephthalate; polypropylene terephthalate; polybutylene terephthalate or polyethylene glycol-1,2-furancarboxylate; polyamides, especially polyamide 6 or polyamide 6,6; polycarbonates; polyether ketones; polyether ether ketones; polyether ketone ketone polyethers; polyether esters; polyphenylene sulfide; polyether imides; copolymers thereof and mixtures thereof.

26. A honeycomb according to any one of claims 15 to 25, characterized in that Also included is a connection region generated by plastic deformation, the connection region being located in one of the cover layer planes.

27. A honeycomb according to any one of the preceding claims, characterised in that The polygonal cell has at least two lateral cell walls forming a double wall having a double material thickness, and the two lateral cell walls of the double wall have a wave shape.

28. A method of manufacturing a honeycomb, the method comprising: Forming a plurality of polygonal cells arranged in an array, each of the polygonal cells having lateral cell walls extending between vertices of each of the polygonal cells, each of the polygonal cells being bounded on two sides by a cover layer, the method comprising: forming the lateral cell wall of each of the polygonal cells into a polygonal ring, and At least one lateral unit wall with a wavy shape is formed for each of the polygonal units, wherein the wavy shape is defined by the deviation from a line connecting two adjacent vertices of a polygonal unit, and at a position where the lateral unit wall with the wavy shape intersects with other lateral units at a connecting portion, the slope of the deviation of the lateral unit wall with the wavy shape is zero.

29. The method according to claim 28, characterized in that The wave shape is a smooth curve without kinks or steps.

30. The method according to claim 28, characterized in that The wavy shape is formed with a sinusoidal, square or triangular cross-section, or with parallel alternating ridges and grooves extending parallel to the longitudinal axis of the honeycomb unit.

31. The method according to claim 30, characterized in that The centers of curvature of the curved portions are on different sides of the lateral cell walls.

32. The method according to any one of claims 28 to 30, characterized in that The wavy shape of the cell wall has three parts: a curved portion in the middle defined by a deviation from a line connecting two adjacent vertices of a cell, the middle portion having two tail or end portions of a wavy shape with a low or zero slope, and the curved portion having no inflection point in the middle.

33. The method according to claim 32, characterized in that Where a lateral wavy cell wall joins other lateral cell walls of the honeycomb at a connection, the deviation of the wavy shape is zero.

34. The method according to any one of claims 28 to 33, characterized in that At one vertex or at some of the vertexes or at each vertex, the deviation of the wavy cell wall is zero or the slope of the wavy cell wall is zero.

35. The method according to any one of claims 28 to 35, characterized in that in, The lateral cell walls formed in the L direction have a wavy shape and the lateral cell walls formed in the W direction are planar, or the lateral cell walls formed in the L direction have a wavy shape and the lateral cell walls formed in the W direction have a wavy shape.

36. The method according to any one of claims 28 to 35, characterized in that This includes forming a plurality of 3D structures by plastic deformation of a sheet material, wherein the 3D structures are folded together to abut or abut one another to form a ring of lateral cell walls.

37. The method according to claim 36, characterized in that A plurality of said polygonal units are bounded by a cover layer plane, two open sides towards each of said polygonal units, whereby said units are each fully or partially bridged in one or the other of said cover layer planes, wherein said plurality of 3D structures are formed by plastic deformation of the sheet material.

38. The method according to claim 28, characterized in that The wavy shape of the lateral cell wall has four parts: two curved parts formed in the middle of the wavy shape, the two curved parts deviate from the line connecting two adjacent vertices of a polygonal unit, two middle parts have an inflection point between them, and two tail or end parts of the wavy shape have a low slope or zero slope, wherein one of the two curved parts is formed into a convex shape and one curved part is formed into a concave shape, or wherein the wavy shape of the lateral cell wall has three parts: one curved part is formed in the middle of the wavy shape and deviates from the line connecting two adjacent vertices of a polygonal unit, and the middle part is connected to two tail or end parts with a low slope or zero slope.

39. The method according to claim 37 or 38, characterized in that The lateral cell walls formed in the L direction are made to have a wavy shape, and the lateral cell walls formed in the W direction are made to be flat, or wherein the lateral cell walls formed in the L direction are made to have a wavy shape, and the lateral cell walls formed in the W direction are made to have a wavy shape.

40. The method according to any one of claims 28 to 39, characterized in that The wavy shape has a deviating amplitude of 5% to 20%, or in the range of 10% to 15%, of the length of the lateral cell wall between vertices of the polygonal cells.

41. The method according to any one of claims 28 to 40, characterized in that The lateral cell walls with the wave shape are formed with double material thickness.

42. The method according to any one of claims 36 to 41, characterized in that The sheet material is one or more sheets of flat bodies, a continuous flat body, multiple sheets of corrugated sheets, a continuous corrugated sheet, an uncut or substantially uncut flat body; wherein the plurality of 3D structures are formed by plastic deformation of the sheet material.

43. The method according to claim 42, characterized in that The 3D structure is a region of polygonal shape, sinusoidal shape or arc shape.

44. The method according to any one of claims 28 to 43, characterized in that At least a portion of each of the lateral cell walls is fully or partially permanently connected to another of the lateral cell walls.

45. The method according to any one of claims 42 to 44, characterized in that The sheet material comprises a plurality of flat bodies, a continuous flat body, one or more corrugated sheets, a continuous corrugated sheet, an uncut or substantially uncut flat body; and is formed of a thermoplastic polymer, a fiber composite material, or a plastically deformable paper or metal sheet.

46. ​​The method according to any one of claims 36 to 45, characterized in that The sheet material is made of a material selected from the following group, the group including fabrics, spunbond or spunbond laid nonwoven fabrics, meltblown nonwoven fabrics, carded nonwoven fabrics, air-laid nonwoven fabrics, wet-laid nonwoven fabrics, knitted fabrics, nets, scrims, two-dimensional mats of extruded entangled filaments, consolidated layers of unidirectional fibers, layers of rubber materials, and three-dimensional structural mats of entangled filaments.

47. The method according to any one of claims 36 to 46, characterized in that At least one side defined by a cover layer plane includes a cover layer attached to at least one side of the honeycomb.

48. The method according to claim 47, characterized in that The cover layer is a two-dimensional layer and comprises or consists of a material selected from the group consisting of a fabric, a spunbonded or spunbonded laid nonwoven, a meltblown nonwoven, a carded nonwoven, an air-laid nonwoven, a wet-laid nonwoven, a knitted fabric, a net, a scrim, a two-dimensional mat of extruded entangled filaments, a consolidated layer of unidirectional fibers, a continuous layer, or a combination thereof.

49. The method according to any one of claims 36 to 48, characterized in that The sheet is composed of a thermoplastic polymer and / or a thermoplastic elastomeric polymer, or a thermoplastic polymer selected from the following group, the group including polyolefins, especially polyethylene or polypropylene; polyesters, especially polyethylene terephthalate; polypropylene terephthalate; polybutylene terephthalate or polyethylene glycol-1,2-furancarboxylate; polyamides, especially polyamide 6 or polyamide 6,6; polyether ketones; polyether ether ketones; polyether ketone ketone polyethers; polyether esters; their copolymers and mixtures thereof.

50. The method according to any one of claims 36 to 49, characterized in that Also included is forming a connection region by plastic deformation, the connection region being located in one or the other of the cover layer planes of the honeycomb.

51. The method according to any one of claims 28 to 50, characterized in that The polygonal unit has at least one double lateral cell wall, and two cell walls of the at least one double lateral cell wall have a wavy shape.

52. The method according to any one of claims 36 to 51, characterized in that The plastic deformation is performed by thermoforming, vacuum forming, rotary vacuum thermoforming, or by means of a non-cutting rotary process.

53. The method according to any one of claims 36 to 44, characterized in that The sheet material is cast or extruded as a corrugated sheet, and then the corrugated sheet is molded to modify the corrugations to form the 3D structure.

54. The method according to claim 53, characterized in that The molding of the corrugations is performed by vacuum molding or thermoforming or by means of a non-cutting rotary process or by means of a rotary vacuum thermoforming process.

55. The method according to any one of claims 28 to 54, characterized in that One, two or more lateral cell walls have an undulating shape and optionally have a periodic or cyclic deviation.

56. An apparatus for manufacturing a honeycomb from a plastically deformable material, the apparatus comprising: means for forming a plurality of polygonal cells arranged in a row, each said polygonal cell having lateral cell walls extending between vertices of each said polygonal cell, each said polygonal cell being bounded on two sides by a cover layer plane; A device for forming the lateral cell wall of each polygonal unit into a polygonal ring, and a device for forming at least one lateral cell wall with a wavy shape belonging to the polygonal unit for each polygonal unit, and the at least one lateral cell wall is connected or integrated with one or two planar lateral cell walls of the polygonal unit to which it belongs, or the at least one lateral cell wall is connected or integrated with one or two planar lateral cell walls of an adjacent polygonal unit, and the slope of the lateral cell wall is zero at the position where the lateral cell wall intersects with other lateral cell walls at the connecting portion.

57. The device according to claim 56, characterized in that The invention comprises a device for forming at least one lateral cell wall having a wave shape for each polygonal cell, and the slope of the wave shape is zero at a position where the at least one lateral cell wall joins to other lateral cell walls of each polygonal cell at a connecting portion.

58. The apparatus according to claim 56 or 57, characterized in that It comprises an apparatus configured to process a flat body into a web, or comprises an apparatus for extruding or casting a flat sheet or web, and processes the sheet or the web using an apparatus for molding at least one cell wall of any polygonal cell to obtain a wavy shape.

59. The device according to claim 58, characterized in that The apparatus for molding is an apparatus for vacuum molding or thermoforming, or an apparatus for a non-cutting rotary process, or an apparatus for a rotary vacuum thermoforming process to form a first 3D structure having at least one cell wall having a wavy shape.

60. The apparatus according to claim 58 or 59, characterized in that The apparatus for casting or extruding a sheet produces a corrugated sheet and also comprises means for molding the corrugated sheet to modify said corrugations, thus forming a first 3D structure with at least one cell wall having a wavy shape.

61. Apparatus according to any one of claims 58 to 60, characterised in that The apparatus for molding is selected from vacuum molding, thermoforming, or an apparatus for a non-cutting rotary process, or an apparatus for a rotary vacuum thermoforming process to form a 3D structure with at least two cell walls or all cell walls having a wavy shape.

62. Apparatus according to any one of claims 58 to 61, characterised in that The apparatus for molding comprises two half-molds having surfaces forming a 3D shape of a first 3D structure in the sheet, the first 3D structure comprising at least one W-cell wall or at least two cell walls having a wavy shape.

63. The device according to claim 62, characterized in that The mould halves are in the form of matching rotating moulds, or are fixed moulds with an upper mould surface and a lower mould surface.

64. Apparatus according to any one of claims 57 to 63, characterised in that Also included is an extruder for extruding the sheet and means for cooling the extruded sheet until it reaches a temperature suitable for molding.

65. The device according to claim 64, characterized in that Also included are means for a further cooling step to solidify the semi-cellular structure into its final shape, and means for folding the semi-cellular structure.

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