Method for producing a sandwich component, core for a sandwich component, and sandwich component

Abstract

The present invention describes a method for manufacturing a sandwich component (1). According to the present invention, a first covering layer (2) is formed on a forming surface (100a) of a forming mold (100); a core (3) is produced by constructing a cell structure (30) with a plurality of cells (35) in a thickness direction (D) on the first covering layer (2) by means of an additive manufacturing method; and a second covering layer (4) is formed on a placement surface (3a) of the core (3) that is placed opposite to the first covering layer (2). In addition, a core (3) for a sandwich component (1) and a sandwich component (1) are described.

Description

[0001] The invention relates to a method for producing a sandwich component, a core for a sandwich component and a sandwich component. Background Art

[0002] Structural components with so-called sandwich construction usually have at least one outer, flatly extending cover layer and a core layer connected to the cover layer. The core layer is designed at least as a honeycomb structure consisting of a low-density material. The cover layer is usually designed as a thin, mechanically resistant, flat layer. In this way, a relatively high mechanical strength or rigidity is achieved with a low component weight, so that structural components with sandwich construction are used in many ways, especially also in aviation and aerospace vehicle construction.

[0003] WO 2015 / 105859 A1 describes a core layer for a sandwich component, which is made of a plurality of open or closed cells by means of a 3D printing method. Usually, the covering layers and the core of the sandwich component are respectively manufactured separately and then connected to each other, for example bonded to each other. Summary of the invention

[0004] One of the objects of the invention is to provide an improved method, in particular a method for manufacturing a sandwich component which is improved in terms of process speed. Another object of the invention is to provide an improved core for a sandwich component, in particular a core which simplifies the manufacture of the sandwich component and / or has improved mechanical properties.

[0005] These objects are accordingly achieved by the present invention.

[0006] Advantageous embodiments and developments result from the invention.

[0007] According to a first aspect of the present invention, a method for manufacturing a sandwich component is provided. According to the present invention, a first covering layer is formed on the forming surface of a forming mold. In this step, a closed, flatly extending layer is formed. This can be achieved, for example, by placing a fiber tape on the forming surface. Here, for example, a so-called prepreg tape (i.e., a tape made of fiber material impregnated with a resin material or a matrix material) is placed on the mold surface along the placement direction by means of a placement head. This can, for example, include forming a plurality of superimposed layers consisting of fiber tapes, wherein these fiber tapes in a layer preferably have the same fiber orientation and these fiber tapes in the adjacently placed layers preferably have a fiber orientation different from the fiber orientation of the layer located below. These fiber tapes optionally exist in a state of a viscous state (Aggregatszustand) of the matrix material at least on the surface, or the matrix material is immediately converted into a viscous state by means of heat supply (for example, by means of a heating device provided at the placement head) after placement. Thus, a single fiber tape and, when appropriate, a single layer of the fiber tape melts. Therefore, an integral, closed, flatly extending first covering layer is formed. Here, the outer surface of the first covering layer is laid on the forming surface of the forming mold. The inner surface of the first cover layer is oriented opposite to the outer surface.

[0008] Alternatively, the first covering layer can also be formed by laying a flat extended fiber semi-finished product onto the forming surface of the forming die and deforming it when appropriate. The fiber band semi-finished product can especially be designed as a flat semi-finished product in a plate shape or a cushion shape, and the semi-finished product has a plurality of layers consisting of a fiber layer embedded in a matrix material. The semi-finished product is pressed onto the forming surface of the forming die with the matrix material at least partially in a viscous state and is correspondingly formed thereby. Alternatively, the matrix material can be hardened or cured before the next step of the method is performed.

[0009] In a further step, the core of the sandwich construction is manufactured by constructing a cell structure with a plurality of cells in the thickness direction on the first cover layer by means of an additive manufacturing method. Thus, the 3D printing method for manufacturing the core is performed directly on the inner surface of the first cover layer. In this way, the core is already connected to the first cover layer when the core is manufactured. This speeds up and simplifies the manufacture of the sandwich component because two method steps are combined in this way. In addition, 3D printing provides an unusual design freedom and in particular allows the manufacture of independently matched cell structures at foreseeable (überschaubarem) costs, which may not be manufactured with common methods or can only be manufactured at significant costs.

[0010] The cell structure is constructed from the inner surface of the lower cover layer along the thickness direction. A plurality of separate cells are designed, and these cells can be designed as closed cells with the help of a plurality of cell walls. These cells can be designed as convex polyhedrons, for example. If the connection path between these points is completely located inside the polyhedron for each two points of the polyhedron, the polyhedron is convex. For example, cells in the shape of a cuboid, a hexahedron, an octahedron, a truncated octahedron, a tetrahedron, a double tetrahedron, a polygonal prism, a dodecahedron, an icosahedron, a truncated icosahedron, etc. can be provided. The thickness direction extends transversely to the inner surface of the lower cover layer. In particular, a cell structure with a constant or changing thickness in the extension direction of the inner surface is designed. The cells of the cell structure that are opposite to the thickness direction and placed on the outermost side form a placement surface with the thickness spacing of the cell structure.

[0011] In a further step, a second covering layer of the sandwich component is formed on a placement surface of the core opposite to the first covering layer. Placing the second covering layer on the placement surface of the core can be carried out in the same way as described for the first covering layer, in particular by placing a fiber tape or by laying a flat extending fiber semi-finished product on the placement surface and deforming it when appropriate. By forming the second covering layer directly on the core, the second covering layer is already connected to the core during placement. Thus, another process step is saved and the method is further accelerated. In addition, when placed on the placement surface of the core, the second covering layer matches the surface direction of the placement surface. In this way, a close flat contact is achieved between the core and the second covering layer, which reduces the risk of delamination between the covering layer and the core.

[0012] Thus, by the method according to the present invention, sandwich components can be manufactured in a single mold device, especially on a single workstation and in a particularly fast manner. The first cover layer can be produced on the mold surface by placing a fiber band or by forming, especially hot forming in an automated manner. For this purpose, a placement device that works automatically, such as a placement head or an end effector, can be used accordingly. By manufacturing the core directly on the first cover layer by means of an additive manufacturing method, a large design freedom can be achieved for the core, wherein a complex mold can be omitted. Since the 3D printing device works based on a data model, manual work steps can be omitted, such as manually orienting the core or the like, which is usually necessary in a common method. In addition, orientation errors can also be avoided and the quality of the sandwich component can be improved by manufacturing the core directly on the first cover layer. The second cover layer can also be produced in an automated manner, similar to the first cover layer. By directly realizing it on the core, a large accuracy is obtained when positioning the cover layer. Thus, by the method according to the present invention, sandwich components can be manufactured in an integrated method or in an integrated method, wherein all work steps are automated and can be performed on a single workstation. As a result, separate components are avoided and waiting times between process steps are shortened, thereby shortening the production time overall.

[0013] According to one embodiment of the method, it is proposed that the fiber bands or fiber semi-finished products for forming the first and / or second covering layers respectively have a thermoplastic matrix material, such as polyphenylene sulfide, short PPS, polyetheretherketone, short PEEK, or similar thermoplastic materials. In particular, fiber bands or fiber semi-finished products based on thermoplastics are used to produce the covering layers. This provides the following advantages in particular: the matrix material can be melted in a simple manner by heat supply and no additional heat treatment is required to harden the matrix material. In particular, the treatment of the covering layer in an autoclave can be omitted in this way, thereby further accelerating the method.

[0014] According to a further embodiment, an FDM 3D printing method is performed as an additive manufacturing method for producing the core. FDM here stands for the abbreviation of the English expression "Fused Deposition Modeling". In this method, the walls forming the cells are produced in such a way that a linear or strip-shaped plastic material is liquefied by heating and applied to the inner surface of the first covering layer by extrusion molding with the aid of a nozzle. The plastic material is then hardened at the desired position by cooling. The construction of the cells is usually carried out repeatedly in such a way that work planes are left accordingly and then pushed upward in a stacked manner, so that the cell structure is produced in a layered manner.

[0015] According to one embodiment, the cell structure of the core is constructed from a thermoplastic material. In particular, it is a thermoplastic plastic material, such as polycarbonate, short PC, polyetherimide, short PEI, or similar thermoplastics. Particularly advantageously, the matrix material of the first and second covering layers and the material of the core can be constructed from a thermoplastic plastic material. In this way, a reliable and mechanically resistant connection is obtained between the core and the covering layer.

[0016] According to one embodiment of the method, it is proposed that the cell structure of the core is formed with a placement edge area placed opposite to the first covering layer in the thickness direction, and the cell density of the placement edge area in terms of volume is greater than the inner area of ​​the cell structure adjacent in the thickness direction. Therefore, a transverse section area is generated at the edge of the cell structure to form a placement surface. Therefore, in this transverse section area, the cells present in a predetermined volume are more than in the same volume in the inner area of ​​the transverse section adjacent to the thickness direction. In this way, the opening of the placement surface limited by the cell wall is reduced when appropriate. Thus, the fiber band is better supported when placed on the placement surface of the core, thereby reliably avoiding pits. In addition, the contact surface between the second covering layer of the core is increased, which improves the adhesion between these layers. A further advantage of this design is that the mechanical rigidity of the core, especially the bending strength, is increased.

[0017] According to a further embodiment, the chamber that is placed opposite to the first covering layer with respect to the thickness direction and forms the placement surface can be designed in the following manner: the longitudinal extension direction of the chamber extends along the placement direction, and the fiber band is placed in the longitudinal direction of the fibers of the fiber band in this placement direction. According to this embodiment, the chamber that is closest to the outside with respect to the thickness direction is designed in the following manner: the fibers of the fiber band (when these fibers are placed on the placement surface along a determined direction) extend along the longitudinal extension direction of the opening of the placement surface surrounded by the chamber walls. If, for example, a rectangular opening is formed in the placement surface by the chamber walls of the chambers, these chamber walls are oriented so that when the fiber band is placed, these fibers extend along the longitudinal sides of the rectangular opening. The advantage provided by this orientation is that the matrix material located between the fibers hardly sags toward the opening. In this way, depressions in the cover layer are reliably avoided.

[0018] According to a further embodiment, the cell which is placed opposite to the first cover layer with respect to the thickness direction and forms the placement surface is filled with a filling material. In this way, the opening of the placement surface surrounded by the cell wall is completely closed. As a result, a particularly large laying surface is provided for the second cover layer, which enables a very reliable adhesion between the cover layer and the core. Pockets in the cover layer are also avoided. In addition, the risk of water or generally liquids entering the interior of the core layer can also be reduced in this way.

[0019] The filling of the cells to form the placement surface can be carried out in particular by means of an additive manufacturing step during the construction of the cell structure. Thus, the cells that are most external in relation to the thickness direction are formed directly as filled solid cells during their construction. Alternatively, the cells can also be subsequently filled with a filling material, for example the material that forms the cells themselves or a foam material.

[0020] According to a further embodiment, it can be provided that the cell structure of the core is formed with a contact edge region directly adjacent to the first covering layer in relation to the thickness direction, the contact edge region having a cell density in terms of volume greater than the inner region of the cell structure adjacent in the thickness direction. It can also be provided in the contact edge region that the cells of the cell structure in direct contact with the first covering layer are filled with a filling material. These optional designs improve the adhesion between the first covering layer and the core and the mechanical resistance of the core. In addition, when the cells are filled, liquid intrusion into the interior of the cell structure is reliably avoided.

[0021] According to a further embodiment of the method, the cell structure of the core for increasing the mechanical strength of the core can be constructed in such a way that regions with a greater cell density in terms of volume are formed as adjacently placed regions. Accordingly, it can be expected that high mechanically loaded transverse section regions of the core can be formed with smaller cells than other transverse section regions, in which low mechanical loads of the core can be expected. In this way, a one-piece core can be advantageously produced at low cost, low weight and high mechanical strength. It can be expected that high mechanically loaded transverse section regions of the core can be, in particular, regions provided for mounting connecting or fastening means such as screws, rivets, bolts, etc. The region in which the local insert is to be embedded can also be a region of high mechanical load.

[0022] Alternatively, the cell structure of the core for increasing the mechanical strength of the core can be formed in such a way that regions are formed in which cells are formed with cell walls made of a material having a greater mechanical strength than the cell walls of the cells in adjacent regions. In this case, in transverse section regions where high mechanical loads of the core can be expected, cell walls are formed of a more resistant or more stable material than in transverse section regions where low mechanical loads of the core can be expected. This offers the advantage that the individual cells can be constructed accordingly with the same geometry, which simplifies the complexity for modeling the core and simplifies the control of the 3D printing device for constructing the core.

[0023] According to a further alternative, the cell structure of the core for increasing the mechanical strength of the core can be designed in such a way that regions are formed in which the cell walls of the cells have a greater wall thickness than the cell walls of the cells in adjacently located regions.

[0024] According to a further alternative, the cell structure of the core for increasing the mechanical strength of the core can be designed in such a way that regions are formed in which the cells are filled with a filling material.

[0025] According to a further embodiment of the method, during the formation of the first covering layer and / or during the production of the core and / or during the formation of the second covering layer, a surface inspection is performed to identify surface defects. Therefore, the quality of the corresponding layer produced by the fiber band can be checked during the placement of the covering layer. This can be achieved, for example, by means of an optical or acoustic method. In particular, a camera or an ultrasonic sensor can be installed on the placement head of the fiber band to identify surface defects or foreign matter. During the production of the core, the surface defects of the corresponding applied material layer of the core can also be checked in an optical or acoustic manner. Performing corresponding inspections while manufacturing the corresponding parts of the sandwich component further shortens the manufacturing process.

[0026] Alternatively or in addition, after forming the second cover layer, provision can be made to inspect the sandwich component for component defects, such as delamination of the cover layer, defective areas or inclusions of foreign matter in the cover layer and the core, without interruption overall. For this purpose, the sandwich component can be irradiated with x-rays.

[0027] According to another aspect of the present invention, a core for a sandwich component is provided, the core having a cell structure having a plurality of cells constructed in the thickness direction by means of an additive manufacturing method. The core can be manufactured in particular in the manner described above and can correspondingly have the features of the core described above.

[0028] The cells are designed as closed cells, in particular by means of cell walls.

[0029] In particular, it can be provided that the cell structure of the core has, relative to the thickness direction, a placement edge region which has a greater cell density in terms of volume than an adjoining inner region of the cell structure in the thickness direction.

[0030] Furthermore, provision can be made for the cells of the core which form the placement surface with respect to the thickness direction to be filled with a filling material.

[0031] According to a further embodiment, the cell structure for increasing the mechanical strength of the core may have the following areas:

[0032] - these areas have a greater density of cells in terms of volume than adjacently placed areas,

[0033] - in these regions the cells have cell walls consisting of a material which has a greater mechanical strength than the cell walls of the cells in adjacently situated regions,

[0034] or

[0035] - the cell walls of the cells in these regions have a greater wall thickness than the cell walls in adjacently placed regions, or

[0036] - In these areas the chambers (35) are filled with a filling material.

[0037] According to a further embodiment of the core, the cell structure has a circumferential edge region, which extends in a transverse direction from the axial edge of the cell structure transversely to the thickness direction, wherein the cell density in terms of volume of the circumferential edge region is greater than the inner region of the cell structure adjacent in the transverse direction. In general, the core has a flat extension surrounded by a circumferential edge. According to this embodiment, a transverse section region extending from the circumferential edge of the core is provided, which extends to the inside of the core through a discrete path and is referred to as the circumferential edge region. In the circumferential edge region, the volume of the cells of the cell structure forming the transverse section of the core is smaller than that in the transverse section region adjacent to the circumferential edge region. In this way, the amount of material of each cell in the circumferential edge region is greater, thereby improving the mechanical strength of the core on the one hand and advantageously making it easy to install fastening devices such as screws, rivets, bolts, etc. in the circumferential edge region on the other hand. For this reason, it can also be proposed alternatively that the cells in the circumferential edge region are filled with filling material.

[0038] According to a further embodiment of the core, it can also be provided that a connection section for fastening the core in a form-fitting manner is formed in the circumferential edge region. For example, the connection section can be formed by a pin extending from the circumferential edge or protruding from the circumferential edge, or a recess extending from the circumferential edge into a transverse section of the core. In this way, the core can be connected to another core in a form-fitting manner particularly easily, which simplifies the installation of a sandwich component having the core.

[0039] The features and advantages of the core described in the context of the method according to the invention apply in an analogous manner to the core described according to this aspect of the invention.

[0040] According to another aspect of the present invention, a sandwich component is provided. The sandwich component has a first covering layer consisting of a fiber composite material, a second covering layer consisting of a fiber composite material, and a core arranged between the first and second covering layers, wherein the core is formed according to the above-described embodiment. The sandwich component can be manufactured in a particularly simple and efficient manner, for example, by means of the method described above.

[0041] Here, in general, "fibrous material" or "fibrous material" is understood to be a material that is composed of a plurality of linear or segmental reinforcing fibers, such as carbon fibers, glass fibers, ceramic fibers, aramid fibers, boron fibers, mineral fibers, natural fibers or plastic fibers or a mixture thereof.

[0042] Here, a “fiber tape” or “prepreg tape” or “fiber semifinished product” is understood to be a fiber material that is impregnated with a resin material or a matrix material, such as a thermosetting, thermoplastic, elastomeric resin or generally a plastic resin, or the fibers of which are embedded in a resin material or a matrix material. In this case, the fiber tapes or prepreg tapes can be combined to form a tape extending in the longitudinal direction. The fiber semifinished product can be formed in particular as a flat and closed mat or plate having a plurality of layers of fiber material stacked one above the other, wherein the fibers in adjacent layers preferably extend in different directions.

[0043] 3D printing methods in the sense of the present application include all generative or additive manufacturing methods, in which objects of a predetermined shape are produced from shapeless materials (such as liquids and powders or neutral shape semi-finished products, such as strips or wires) based on a geometric model in a specific generative manufacturing system by means of chemical and / or physical processes. In this case, 3D printing methods in the sense of the present invention use additive processes, in which the starting material is structured into a predetermined shape in a sequential, layered manner.

[0044] In this case, “one-piece”, “integral”, “integral” or “single-piece” components are generally understood to mean that they exist as a single part that forms a material unit and are in particular manufactured as such, wherein one of the other parts cannot be detached from the other parts without eliminating the material bond.

[0045] Here, for directional specifications and axes, in particular for directional specifications and axes that form the direction of physical structures, the direction of an axis, direction or structure "along" another axis, direction or structure is to be understood as meaning that tangents obtained in particular at corresponding parts of these structures extend respectively at an angle of less than or equal to 45 degrees, preferably less than 30 degrees, and particularly preferably parallel to each other.

[0046] Here, for directional specifications and axes, in particular for directional specifications and axes that form the direction of physical structures, an axis, direction or structure that is "transverse" to the direction of another axis, direction or structure is understood to mean that tangents obtained at corresponding locations of these structures extend at an angle greater than or equal to 45 degrees, preferably greater than or equal to 60 degrees, and particularly preferably perpendicular to each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present invention will be explained below with reference to the accompanying drawings. In the accompanying drawings:

[0048] Figure 1 A schematic view showing a first step of a method for manufacturing a sandwich component according to an embodiment of the present invention;

[0049] Figure 2 A schematic diagram showing another step of the method according to an embodiment of the present invention;

[0050] Figure 3 A schematic diagram showing another step of the method according to an embodiment of the present invention;

[0051] Figure 4 shows a schematic cross-sectional view of a sandwich component according to an embodiment of the present invention;

[0052] Figure 5 shows a schematic cross-sectional view of a core according to an embodiment of the present invention;

[0053] Figure 6 shows a schematic cross-sectional view of a core according to another embodiment of the present invention;

[0054] Figure 7 A schematic top view showing a core placement surface according to another embodiment of the present invention;

[0055] Figure 8 Shows Figure 7 A detailed view of the area marked by the letter X;

[0056] Fig. 9 shows a schematic cross-sectional view of a sandwich component according to another embodiment of the present invention;

[0057] Fig.10 shows a schematic cross-sectional view of a sandwich component according to another embodiment of the invention, the sandwich component having a core according to another embodiment of the invention;

[0058] Fig.11 shows a schematic cross-sectional view of a sandwich component according to another embodiment of the invention, the sandwich component having a core according to another embodiment of the invention;

[0059] Fig.12 shows an arrangement of two sandwich components, each according to another embodiment of the invention; and

[0060] Fig.13 A schematic cross-sectional view of a core according to another embodiment of the invention is shown.

[0061] In the figures, unless otherwise indicated, the same reference numerals denote identical or functionally identical components. DETAILED DESCRIPTION

[0062] Figures 1 to 3 The sequence of a method for producing a sandwich component 1 is schematically shown.

[0063] exist Figure 1 1 shows the first step of the method, in which the first covering layer 2 of the sandwich component 1 is formed. The first covering layer 2 is formed optionally by placing a first fiber band 20 on the forming surface 100a of the forming mold 100. The first fiber band 20 accordingly has fibers F, which are embedded in a matrix material M, in particular a thermoplastic matrix material (for example PPS or PEEK). The first covering layer 2 is formed by placing at least one flat, closed layer 21 of the first fiber band 20. Optionally, it is also possible to place a plurality of layers such as Figure 1 21 shown by way of example in the figure. Here, the first fiber bands 20 in the adjacent layers 21 have different fiber orientations. Optionally, these first fiber bands 20 are placed in the following state, wherein the matrix material M is in a viscous physical state at least on the surface of the corresponding first fiber bands 20. Instead of this, the matrix material M is converted into a viscous state by heat supply immediately after placement. Thus, the individual first fiber bands 20 and the individual layers 21 melt when appropriate, and form an integral, flatly extended first covering layer 2. The first covering layer 2 can also be formed by laying a fiber semi-finished product (not shown) on the forming surface 100a. Here, a flat mat (which has a multilayer fiber material impregnated with a matrix material) is pressed on the forming surface 100a, and thus deformed correspondingly to the surface contour of the forming surface 100a. The matrix material is in a state suitable for deformation here. For example, by applying vacuum to the forming surface 100a by means of a second die (not shown), by means of a roller (not shown) or in a similar manner, it is possible to achieve laying on the forming surface 100a.

[0064] The forming surface 100a of the forming die 100 may be three-dimensional relative to the described surface (e.g., Figures 1 to 3 The shape or direction of the first cover layer 2 is defined by the design of the shaped surface 100a.

[0065] For example, the placement of the first fiber band 20 can be achieved by means of the placement head 101, such as in Figure 1 For this purpose, the depositing head 101 has one or more guide rollers or depositing rollers 102 , by means of which the first fiber bands 20 are guided to the surface on which they are to be deposited and optionally pressed onto these surfaces.

[0066] like Figure 1 Schematically shown, the placement head 101 can also have an optional heating device 103 and a likewise optional inspection device 104. The optional heating device 103 is used to melt the matrix material M of the first fiber band 20. The inspection device 104 can be designed, for example, as a camera or an ultrasonic detector for optically inspecting the surface of the first fiber band 20 during the placement process in order to identify surface defects.

[0067] In order to form the first covering layer 2, the placing head 101 is moved along the forming surface 100a of the forming mold 100 in the placing direction L4, and the first fiber band 20 is laid on the forming surface 100a by means of a guide roller or a placing roller 102, or when appropriate, on the already placed layer 21. Here, the first fiber band 20 can be optionally heated by means of a heating device 103 during the placing process. Alternatively or in addition, the surface defects or placement errors of the surface of the already placed first fiber band 20 are checked by means of an inspection device 104 during the placing process. After forming the first covering layer 2, the outer surface 2b of the covering layer 2 is laid on the forming surface 100a. The inner surface 2a of the covering layer 2 is oriented oppositely to the outer surface 2b.

[0068] In this method Figure 2 In a further step, shown by way of example in FIG. 1 , the core 3 of the sandwich component 1 is produced. For this purpose, a cell structure 30 having a plurality of cells 35 is formed on the first cover layer 2 in the thickness direction D by means of an additive or generative production method. This can be achieved, for example, by means of an FDM 3D printing method, for example in Figure 2 FDM is an abbreviation of the English expression "Fused Deposition Modeling". Figure 3 As shown, these cells 35 are produced here by means of a 3D printing device 50. The printing device is guided from the cell wall 36 forming the cell 35 along the inner surface 2a of the first cover layer 2 in accordance with the desired course, as shown in Figure 23D printing device 50 is preferably guided in a working plane above the inner surface 2a. These chamber walls 36 are produced in the following manner: a linear or strip-shaped plastic material K is liquefied by heating with the aid of a heating device 51 provided in the 3D printing device 50, and is applied to the inner surface 2a of the first cover layer 2 by extrusion molding with the aid of a nozzle 52 of the 3D printing device 50. The plastic material hardens there by cooling. The construction of the chamber 35 is repeated in that a working plane is left accordingly, and then the working plane is pushed upward (i.e., in the thickness direction D) in a stacked manner, thereby increasing the distance from the inner surface 2a. The chamber structure 30 is thus formed in a layered manner along the thickness direction D.

[0069] like Figure 2 As shown exemplarily and schematically in FIG. 1 , the 3D printing device 50 can have a storage roller 53 and a guide device 54, wherein the storage roller is used to store and provide the plastic material K in a strip shape, and the guide device is, for example, Figure 3 The rollers shown are in the form of a pair of rollers and are used to guide the plastic material K in strip form.

[0070] The core 3 produced in the above-described manner has a flat extension extending along the inner surface 2a of the first cover layer 2. Figure 3 As shown, the cell structure 30 of the core 3, in particular the cell walls 36 of the cells 35 of the cell structure 30 located outermost relative to the thickness direction D, form a placement surface 3a of the core 3. The thickness d3 of the core 3 relative to the thickness direction D can vary along the flat extension of the core 3 (e.g., as exemplarily shown in FIG. Figure 3 ) or is constant.

[0071] In particular, thermoplastic materials K such as polycarbonate (PC for short), polyetherimide (PEI for short) or similar thermoplastics may be used as plastic materials.

[0072] In this method Figure 3In another step shown exemplarily in the figure, the second covering layer 4 of the sandwich component 1 is formed. For this reason, the second fiber tape 40 is preferably placed on the placement surface 3a of the core 3. The second fiber tape 40 can be constructed in particular as the first fiber tape 20 described above for forming the first covering layer 2. By placing at least one flat, closed layer 41 of the second fiber tape 40, the second covering layer 4 is formed. Optionally, multiple layers 41 can be placed in a superimposed manner. Optionally, these second fiber tapes 40 are placed in a state in which the matrix material M is in a viscous physical state at least on the surface of the corresponding second fiber tape 40. Instead of this, the matrix material M is converted into a viscous state by heat supply immediately after placement. Thus, the individual second fiber tapes 40 and, when appropriate, the individual layers 41 melt, and form an integral, flatly extended second covering layer 4 and are simultaneously connected to the core 3.

[0073] The second cover layer 4 can also be formed by laying a fiber semi-finished product (not shown) on the placement surface 3a of the core 3. Here, a flat mat (which has a plurality of layers of fiber material impregnated with matrix material) is pressed onto the placement surface 3a and thereby deformed in accordance with the surface contour of the placement surface 3a. The matrix material is in a state suitable for deformation. Laying on the placement surface 3a can be achieved, for example, by applying a vacuum to the placement surface 3a with the aid of a second pressing die (not shown), with the aid of a roller (not shown) or in a similar manner.

[0074] During the production of the core 3, a surface inspection can also be optionally performed in order to identify defects in the cell structure. This can be achieved, for example, by means of an inspection device (not shown) optionally provided on the 3D printing device 50, in particular in the form of a camera or an ultrasonic detector.

[0075] For placing the second fiber band 40, the above-mentioned placement head 101 can be used in the same way as for forming the first covering layer 2. In particular, the second fiber band 40 can be optionally heated by means of a heating device 103 during the placement process. Optionally, the surface of the placed second fiber band 40 can also be inspected for surface defects or placement errors by means of an inspection device 104 during the placement process. After the second covering layer 4 is formed, the inner surface 4a of the second covering layer 4 is laid on the placement surface 3a of the core 3 or is connected to the placement surface in a material-matched manner.

[0076] Figure 4 A sandwich component 1 produced according to the method is shown, which has a first cover layer 2 , a second cover layer 4 and a core 3 arranged between the first cover layer 2 and the second cover layer 4 .

[0077] The core 3 for the sandwich component 1 is described below. Figures 1 to 3The method explained is produced directly on the first cover layer 2 by an additive or generative manufacturing method, as described above. Alternatively, the core 3 is produced by means of an additive or generative manufacturing method on a contour surface provided for this purpose (for example, the forming surface 100a of the forming mold 100). In order to produce the core 3 by means of an additive or generative manufacturing method, for example, a process of producing the core 3 by means of a Figure 2 The FDM method is explained, in which the cell walls 36 of the individual cells 35 of the cell structure 30 are formed by applying plastic material K in a layered manner according to the desired course of the cell walls which is described in detail below.

[0078] Figure 5 and 6 Each shows a core 3 having a cell structure 30 constructed in a thickness direction D by means of an additive manufacturing method, the cell structure having a plurality of cells 35. The cells 35 are each formed by a plurality of cell walls 36 and can in particular be present as closed cells 35. The core 3 has a flat extension, in particular along a transverse direction C extending transversely to the thickness direction, for example from Figure 6 In addition, the core 3 also has a first thickness edge region 3A and a second thickness edge region 3B placed opposite thereto with respect to the thickness direction D. The cell walls 36 constituting the cells of the cells 35 or the second thickness edge region 3B located at the outermost relative to the thickness direction D form a construction surface or contact surface 3b of the core 3. In the above-mentioned method for manufacturing the sandwich component 1, the contact surface 3b is laid on the inner surface 2a of the first covering layer 2, or the second thickness edge region 3B is first produced when constructing the cell structure 30. The cell walls 36 constituting the cells of the cells 35 or the first thickness edge region 3A located at the outermost relative to the thickness direction D form a placement surface 3a of the core 3, on which the second fiber tape 40 is placed in order to form the second covering layer 4. The first thickness edge region 3A therefore constitutes a placement edge region 31 of the cell structure 30.

[0079] like Figure 5 As shown, the placement edge region 31 may have a greater cell density in terms of volume than the inner region 32 of the cell structure 30 adjacent in the thickness direction D. The inner region 32 of the cell structure 30 is placed between the first and second thickness edge regions 3A, 3B of the core 3 with respect to the thickness direction D. In addition, optionally, the cell density in terms of volume of the cell structure 30 in the second thickness edge region 3B of the core 3 may also be greater than that of the inner region 32, as shown in FIG. Figure 5 As shown by way of example. Figure 5In the core 3 shown in the example, the cells 35 constituting the inner region 32 of the cell structure 30 have substantially the same size or volume. Therefore, in the above-described method for manufacturing the sandwich component 1, when constructing the cell structure 30 by means of a 3D printing device method, the second thickness edge region 3B of the core 3 is first formed, optionally as a contact edge region with a higher cell density in terms of volume, such as Figure 5 As shown. Then the inner region 32 is formed and then the first thickness edge region 3A is formed, wherein a placement edge region 31 is optionally formed in or through the first thickness edge region 3A, which has a greater cell density in terms of volume than the inner region 32. The contact surface for laying on the cover layer 2, 4 is correspondingly increased by the optionally correspondingly increased cell density in the first and second thickness edge regions 3A, 3B. As a result, the cover layer can adhere better to the core 3 and the core 3 has a greater mechanical stiffness.

[0080] Figure 6 The core 3 is shown exemplarily, wherein the cells 35 constituting the placement surface 3a of the core 3 are filled with a filling material. Figure 6 As can be seen in FIG. 1 , here, the cells 35 of the first thickness edge region 3A or placement edge region 31, which are located outermost with respect to the thickness direction D, are filled with filling material. In this way, the openings or recesses surrounded by the cell walls 36 are filled, thereby forming a closed placement surface 3a, such as Figure 6 Optionally, the outermost cells 35 of the second thickness edge region 3B relative to the thickness direction D can also be filled with a filling material. For example, when the cells 35 are produced by means of an additive manufacturing method, the cells 35 can be filled when the cell structure 30 is constructed.

[0081] Also like Figure 6 and 13 As shown, in order to increase the mechanical strength of the core 3 of the cell structure 30, regions 37 can be provided which have a greater cell density in terms of volume than adjacently placed regions 38. Figure 6 In the core 3 shown by way of example in FIG. 3 , a first subregion 37 with a high cell density is provided in the inner region 32, which extends transversely to the thickness direction D. The first subregion 37 is placed between two second subregions 38 with respect to the thickness direction D, which each have a smaller cell density in terms of volume than the first subregion 37. Alternatively or in addition, it can also be provided that the cell walls 36 of the cells 35 of the first subregion 37 are composed of a material having a greater mechanical strength than the cell walls 36 of the cells 35 of the second subregion 38. Furthermore, the cell walls 36 of the cells 35 of the first subregion 37 can also have a greater wall thickness than the cell walls 36 of the cells 35 of the adjacently placed subregion 38.

[0082] exist Fig.13 In the core 3 shown in the example of FIG. 1 , a first sub-region 37 is provided, which extends along the thickness direction D between the placement surface 3a and the contact surface 3b of the core 3 placed opposite to the thickness direction D. The first sub-region 37 can be designed in particular as a column, such as Fig.13 , and has a greater cell density in terms of volume than the second sub-region 38 surrounding the first sub-region. Of course, instead of increasing the cell density, it can also be provided that the cells 35 of the first sub-region 37 are filled with a filling material, have a greater wall thickness or are made of a more resistant material than the cells 35 of the second sub-region 38. Fig.13 It is also shown by way of example in FIG. 3 that a recess 60 extending between the placement surface 3a and the contact surface 3b can be formed in the first sub-region 37. The recess can be provided, for example, to accommodate a fastening device, such as a bolt or the like.

[0083] Figure 7 and 8 Each shows a top view of the placement surface 3a of the core 3. Figure 8 4 shows a second fiber band 40, which is placed on the placement surface 3a of the core 3 during the execution of the above-described method, for example, when forming the second cover layer 4. When manufacturing the core 3, the cells 35 constituting the placement surface 3a have been formed, i.e., at least in a subregion of the flat extension of the placement surface 3a, cells 35 are formed which are placed opposite to the first cover layer 2 with respect to the thickness direction D, i.e., open cells 35. That is, the cell walls 36 constituting the cells 35 define a recess or opening 35A, such as Figure 6 When the second fiber band 40 is placed on the placement surface 3a of the core 3, it should be avoided as much as possible that the second fiber band 40 extending through the opening 35A sags (which may occur in particular due to the sticky state of the matrix material M) to avoid the formation of depressions in the second cover layer 4 of the sandwich component 1. Figure 5 In the core 3 shown by way of example in FIG. 3 , the risk of sagging is avoided because the openings 35A are made as small as possible by placing an increased cell density in the edge region 31 . Figure 6 In the core 3 shown in FIG. 1 , these openings 35A are filled. Figure 8 In the alternative design of the core 3 shown, the cells 35 in the placement edge region 31 are oriented or correspondingly formed with their cell walls 36 corresponding to the placement direction L4 of the second fiber band 40. Figure 8In the embodiment, the cell wall 36 defines a rectangular opening 35A having a longitudinal extension along the direction L35. The longitudinal extension L35 extends along the placement direction L4, and the second fiber band 40 is placed along the placement direction with its fiber longitudinal direction LF. In this way, the inherently rigid fibers F longitudinally span the opening 35A, thereby avoiding sagging.

[0084] Figures 9 to 12 An alternative design of a sandwich component 1 is shown. The sandwich component 1 can be produced in particular by means of the method described above and has in particular a core 3 which can be formed in the manner described above.

[0085] Fig. 9 The sandwich component 1 shown by way of example in Figure 5 The core 3 shown in FIG. is arranged between the first cover layer 2 and the second cover layer 4 with respect to the thickness direction D. The first cover layer is connected to the outermost cells 35 of the second thickness edge region 3B of the core 3 with respect to the thickness direction D. The second cover layer 4 is connected to the outermost cells 35 of the first thickness edge region 3A with respect to the thickness direction D, or is connected to the placement surface 3a of the core. Fig. 9 As shown, the first cover layer 2 and the second cover layer 4 each extend through the circumferential edge 33 of the core 3 or the cell structure 30 of the core 3. The circumferential edge 33 surrounds or limits or defines a flat extension of the core 3. The area of ​​the first cover layer 2 extending beyond the circumferential edge 33 and the area of ​​the second cover layer 4 extending beyond the circumferential edge 33 are connected to each other in a materially compatible manner and form a circumferential edge region 5 of the whole of the sandwich component 1. If the second fiber tape 40 is placed on the inner surface 2a of the lower cover layer 2 over the circumferential edge 33 of the cell structure 30 by means of the sticky state of the matrix material M, a materially compatible connection can be formed when the second fiber tape 40 is placed and when the second cover layer 4 is formed. The circumferential edge region 5 can be used in particular for structurally connecting the sandwich component 1 and, for example, for attaching fastening devices such as screws, rivets, bolts, etc.

[0086] Fig.10 1 shows a cross-sectional view of another optional design of the circumferential edge region 5 of the sandwich component 1. Fig.10As shown by way of example in the figure, the cell structure 30 of the core 3 has a circumferential edge region 39, which extends from the circumferential edge 33 of the cell structure 30, in particular extends transversely to the thickness direction D into the interior of the cell structure 30. The cells 35 of the circumferential edge region 39 of the cell structure 30 are filled with a filling material, which can be done in particular when constructing the cell structure 30. Therefore, the cell structure 30 can be constructed with a solid circumferential edge region 39. As an alternative to this, the cells 35 of the circumferential edge region 39 of the cell structure 30 can be filled with a filling material subsequently. The first and second covering layers 2, 4 overlap with the circumferential edge region 39 of the cell structure 30 and are closed flush with the circumferential edge 33 of the cell structure 30. Filling the cells 35 offers the advantage of reliably avoiding the intrusion of liquid into the interior of the core 3. In addition, fastening devices such as screws, rivets, bolts, etc. can be introduced into the filled cells 35 and anchored there with high reliability and load-bearing capacity. If these covering layers are also filled, such as Fig.10 As shown by way of example in FIG. 4 , in the cells 35 which are located outermost with respect to the thickness direction D, a reliable adhesion is obtained between the core 3 and the cover layers 2 , 4 .

[0087] Fig.11 A cross-sectional view of another alternative design of the circumferential edge region 5 of the sandwich component 1 is shown. Fig.10 The difference is: Fig.11 The cells 35 of the circumferential edge region 39 of the cell structure 30 of the core 3 of the sandwich component 1 shown by way of example are not filled with a filling material, but have a greater cell density in terms of volume than the inner region 32 of the cell structure 30 adjacent to the circumferential edge region 39. This provides the following advantages: the mechanical stiffness of the core 3 is increased while keeping the weight of the core low. In this design, the installation of the fastening device in the circumferential edge region 39 is simplified and the adhesion between the core 3 and the cover layers 2, 4 is improved.

[0088] Fig.12 The arrangement of a sandwich component 1 is shown. Here, the circumferential edge regions 5 of the sandwich components 1 are mechanically coupled to one another. Fig.12 A further optional design of the circumferential edge region 5 of the sandwich component 1 is also shown. Fig.10 As explained, the circumferential edge region 39 of the cell structure 30 of the core 3 of the sandwich component 1 is formed with filled cells 35 or is formed solid. Fig.12 As shown in FIG. 3 , connecting sections 39A, 39B are formed in the respective circumferential edge regions 39. The connecting sections can be realized in particular in the form of pins 39A or recesses 39B. Fig.12 In the sandwich component 1 (which is Fig.12The circumferential edge region 39 of the cell structure 30 of the core 3 (located below in the illustration of the embodiment of the present invention) has a pin 39A protruding from the circumferential edge region 39 in the thickness direction D. Of course, the pin 39A can also extend from the circumferential edge 33 transversely to the thickness direction D, or from the circumferential edge region 39. The sandwich component 1 (which is located at the bottom) has a pin 39A protruding from the circumferential edge region 39 in the thickness direction D. Fig.12 The circumferential edge region 39 of the cell structure 30 of the core 3 (located at the top in the illustration of FIG. 1 ) has a recess 39B extending from the circumferential edge 33 transversely to the thickness direction D. Of course, the recess 39B can also extend along the thickness direction D, or generally extend into the circumferential edge region 39. Fig.12 As shown in FIG. 3 , the pin 39A is introduced into the recess 39B, whereby a positive-fitting fastening of the core 3 is achieved.

[0089] Although the invention has been explained above by way of example with the aid of exemplary embodiments, the invention is not restricted thereto but can be modified in many ways. In particular, combinations of the aforementioned exemplary embodiments are also conceivable.

[0090] List of Reference Numerals

[0091] 1 Sandwich components

[0092] 2 First covering layer

[0093] 2a Inner surface of the first covering layer

[0094] 2b Outer surface of the first covering layer

[0095] 3 core

[0096] 3A Core first thickness edge area

[0097] 3a Core placement surface

[0098] 3B Second thickness edge area of ​​the core

[0099] 4 Second covering layer

[0100] 4a Inner surface of the second covering layer

[0101] 5 Circumferential edge area of ​​sandwich components

[0102] 20, 40 First fiber band, second fiber band

[0103] 21, 41 floors

[0104] 30-core chamber structure

[0105] 31 Placement edge area of ​​the cell structure

[0106] 32 Internal area of ​​the cell structure

[0107] 33 Circumferential edge of cell structure

[0108] 35 cabins

[0109] 35A Recess or opening

[0110] 36 cell wall

[0111] 37 Area of ​​cell structure

[0112] 38 Cell structure area

[0113] 39 Circumferential edge area of ​​the cell structure

[0114] 39A Pin

[0115] 39B concave part

[0116] 50 3D printing equipment

[0117] 51 Heating device for 3D printing equipment

[0118] 52 Nozzle of 3D printing equipment

[0119] 53 Storage roller

[0120] 54 Guidance Device

[0121] 60 recess

[0122] 100 Forming die

[0123] 100a forming surface

[0124] 101 Place Head

[0125] 102 Guide roller or placement roller

[0126] 103 Heating device

[0127] 104 Inspection device

[0128] C Horizontal direction

[0129] D Thickness direction

[0130] d3 core thickness

[0131] F Fiber

[0132] K Plastic material

[0133] L4 placement direction

[0134] L35 Longitudinal extension of the chamber

[0135] LF Fiber longitudinal direction

[0136] M Matrix material

[0137] P1 Arrow

Claims

1. A method for producing a sandwich component (1), comprising the following steps: Forming a first covering layer (2) on the forming surface (100a) of the forming mold (100) by placing a first fiber tape (20) on the forming surface (100a) of the forming mold (100) or by laying a flat and extended fiber semi-finished product on the forming surface (100a) of the forming mold (100); The core (3) is produced by constructing a cell structure (30) with a plurality of cells (35) on the first cover layer (2) in the thickness direction (D) by means of an additive manufacturing method; A second covering layer (4) is formed on the placement surface (3a) of the core (3) which is placed opposite to the first covering layer (2) by placing a second fiber tape (40) on the placement surface (3a) of the core (3) or by laying a flat and extended fiber semi-finished product on the placement surface (3a) of the core (3).

2. The method according to claim 1, wherein: The first fiber band (20) for forming the first covering layer (2) and / or the second fiber band (40) for forming the second covering layer (4) or the fiber semi-finished product for forming the first covering layer (2) and / or the fiber semi-finished product for forming the second covering layer (4) each have a thermoplastic matrix material.

3. The method according to claim 1 or 2, wherein: An FDM-3D printing method is performed as an additive manufacturing method for manufacturing the core (3).

4. The method according to claim 1 or 2, wherein: The cell structure (30) of the core (3) is constructed from a thermoplastic material.

5. The method according to claim 1 or 2, wherein: The cell structure (30) of the core (3) is formed with a placement edge area (31) placed opposite to the first covering layer (2) relative to the thickness direction (D), and the placement edge area has a cell density in terms of volume that is greater than the inner area (32) of the cell structure (30) adjacent to it in the thickness direction (D).

6. The method according to claim 1 or 2, wherein: The small chamber (35) which is placed opposite to the first covering layer (2) relative to the thickness direction (D) and forms the placement surface (3a) is designed in the following manner: the longitudinal extension (L35) of the small chamber (35) extends along the placement direction (L4) in which the second fiber band (40) is placed in the fiber longitudinal direction (LF) of the second fiber band.

7. The method according to claim 1 or 2, wherein: The cell (35) which is placed opposite to the first cover layer (2) with respect to the thickness direction (D) and forms the placement surface (3a) is filled with a filling material.

8. The method according to claim 7, wherein: The filling of the cells (35) for forming the placement surface (3a) is carried out by means of the additive manufacturing method when constructing the cell structure (30).

9. The method according to claim 1 or 2, wherein: The cell structure (30) of the core (3) for increasing the mechanical strength of the core (3) is constructed in such a way that the following regions (37) are formed: - said area has a greater cell density relative to volume than an adjacently placed area (38), or - forming in said region cells (35) having cell walls (36) made of a material having a greater mechanical strength than the cell walls (36) of cells (35) in adjacently disposed regions (38), or - the cell walls (36) of the cells (35) in said region have a greater wall thickness than the cell walls (36) of the cells (35) in an adjacently disposed region (38), or - In said region said cells (35) are filled with a filling material.

10. The method according to claim 1 or 2, wherein: During the formation of the first cover layer (2) and / or during the production of the core (3) and / or during the formation of the second cover layer (4), a surface inspection is performed to identify surface defects.

11. A sandwich component (1) manufactured by means of a method according to any one of the preceding claims, comprising: A first covering layer (2) consisting of a fiber composite material; a second covering layer (4) consisting of a fiber composite material; A core (3) is arranged between the first covering layer (2) and the second covering layer (4), wherein the cell structure (30) of the core (3) has a placement edge area (31) relative to the thickness direction (D), and the cell density of the placement edge area is greater in terms of volume than the inner area (32) adjacent to the cell structure (30) in the thickness direction (D), wherein the cells (35) in the placement edge area (31) are oriented corresponding to the placement direction (L4) of the second fiber band (40) by means of their cell walls (36).

12. The sandwich component (1) according to claim 11, wherein: The cells (35) forming the placement surface (3a) of the core (3) with respect to the thickness direction (D) are filled with a filling material.

13. The sandwich component (1) according to claim 11 or 12, wherein: The cell structure (30) for improving the mechanical strength of the core (3) has the following areas (37): - said area has a greater cell density relative to volume than an adjacently located area (38), - in said region the cells (35) have cell walls (36) made of a material having a greater mechanical strength than the cell walls (36) of the cells (35) in the adjacently disposed region (38), or The cell walls (36) of the cells (35) in said region have a greater wall thickness than the cell walls (36) of the cells (35) in the adjacently disposed region (38).

14. The sandwich component (1) according to claim 11 or 12, wherein: The cell structure (30) has a circumferential edge region (39) extending from a circumferential edge (33) of the cell structure (30), wherein the circumferential edge region (39) has a greater density in terms of volume than an inner region (32) of the cell structure (30) adjacent to the circumferential edge region (39), or wherein the cells (35) of the circumferential edge region (39) are filled with a filling material.

15. The sandwich component (1) according to claim 14, wherein: A connecting section (39A; 39B) is formed in the circumferential edge region (39) for fastening the core (3) in a form-fitting manner.

16. The sandwich component (1) according to claim 15, wherein: The connecting section (39A; 39B) is in the form of a pin (39A) or a recess (39B).

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