CN101389423A - Method for producing a three-dimensional frame structure for use as a core structure in a sandwich construction and frame structure produced thereby - Google Patents

Abstract

The present application relates to a method for manufacturing a three-dimensional frame structure for use as a core structure in a sandwich construction. Furthermore, the invention relates to a frame structure for a sandwich construction, which is produced according to the method according to the invention. In this method, a two-dimensional grid structure (1) is manufactured from strip-shaped linear semi-finished products (2, 3) in which the semi-finished products (2, 3) intersect at defined intersection points (4); Linear semi-finished products (2, 3) are joined at intersection points (4) and in each case by local application of heat to the lattice structure (1) along three non-intersecting (imaginary) straight lines (5, 6) It softens. In order to give the lattice structure (1) a three-dimensional shape, a force (F) is introduced into the lattice structure (1) along the middle of the (imaginary) straight lines (5, 6) to which heat is applied, where due to the Deformation of the structure, the deflection of the introduced force (F) into a pair of tensions acting on the semi-finished product, so that the grid structure (1) Pull in the third dimension.

Description

Method for producing a three-dimensional frame structure for use as a core structure in a sandwich construction and frame structure produced thereby

References to related applications

This application claims the benefit of German Patent Application No. 10 2006 008728.3, filed February 24, 2006, and U.S. Provisional Patent Application No. 60/776,524, filed February 24, 2006, the disclosures of which are hereby incorporated by reference way into this article.

technical field

The invention relates to the technical field of composite materials. In particular, the invention relates to a method for manufacturing a three-dimensional frame structure for use as a core structure in a sandwich construction. Furthermore, the invention relates to a frame structure for a sandwich construction manufactured according to the method according to the invention and to an aircraft comprising structural components in the form of a sandwich construction whose core structure utilizes Made according to the method of the present invention.

Background technique

Due to their good ratio of stiffness or strength to density, especially sandwich constructions, composite materials have a wide range of applications in the field of aircraft construction. In general, the sandwich construction consists of top and bottom cladding layers and a honeycomb-shaped core, for example, composed of vertically extending hexagonal cross-sectional cells located between the top and bottom cladding layers for rigidity. structure formed.

As an alternative to designs including honeycomb structures, rigid porous materials may be used. However, sandwich constructions comprising a core of rigid porous material suffer to the extent that they have inferior mechanical properties when compared with sandwich constructions having a honeycomb core structure and similar density. To remedy this shortcoming, fibers, filaments or pultruded semi-finished frames can be incorporated in rigid porous materials at defined angles and at defined densities. In the case of incorporation of fibers or filaments and the subsequent resin impregnation procedure, the fibers contribute to the mechanical strength of the porous material. In this case, the porous material not only serves as a carrier for holding the needles in place in the form of resin-reinforced fibers or filaments, but also serves to stabilize the needles to prevent, or at least postpone, when said needles any warping or breaking of the object under load.

However, since the load-bearing capacity of this reinforced rigid porous material is mainly determined by the introduced needles or the introduced pultruded semi-finished frame, existing porous cores tend in an undesired manner to This results in an increase in the density of the core structure. Also typically, the strength-enhancing cellular material structure includes only very small regions that are elastic under load, which generally tends to cause plastic and permanent damage to the composite. Finally, sandwich constructions with porous materials that increase stiffness cannot be ventilated and drained because the spaces between the covering layers are completely filled with rigid porous materials.

For example from WO 2004/022869 A2 and WO 03/101721 A1, known methods are used to manufacture three-dimensional grid structures, in which a metal grid structure is first produced, and the The metal grid structure bends towards the third dimension, resulting in a three-dimensional grid structure. During this bending, the lateral borders of the metal mesh grid are not held in place as this would prevent any bending into the third dimension. However, this bending with the lower mold and the corresponding upper mold is rather inflexible, since changing the angle of the grid structure and changing the height of the grid structure requires changing the lower mold and the corresponding upper mold.

US 3,884,646 also describes a method of manufacturing a three-dimensional lattice structure for use as a core structure in a sandwich construction. In this method, a planar grid structure is first formed from a metal sheet, which is then bent and again given a three-dimensional shape by means of a lower mold and a corresponding upper mold in a forming step. shape.

However, the three-dimensional grid structure produced according to the above-mentioned printed publication is not related to the above-mentioned disadvantages of the porous material reinforced core structure. not flexible.

Contents of the invention

Among other things, a method for producing a three-dimensional frame structure without the use of a carrier material such as a rigid porous material is to be pointed out, wherein said frame structure is superior to the described use of lower molds and The forming method of the upper mold is more flexible.

If the term "strip-shaped linear semi-finished product" is used in the context of the present invention, it refers to a pultruded, extruded or drawn strip-shaped geometric shape with a defined cross-section, which may be, for example, a circle shape, triangle, rectangle, hexagon, tube, or some similar geometric shape. Semi-finished products can be produced with or without reinforcing fibers for reinforcement. Semi-finished products may for example comprise: extruded thermoplastics; pultruded (partially cross-linked) polymers, especially thermoset materials or duromers; extruded metals or ceramics, especially extruded Bulk ceramics, in which thermoplastic and thermosetting plastic materials (hard bodies) can additionally comprise reinforcing fibers.

According to a first aspect of the invention, the object of the invention can be achieved by a method for manufacturing a three-dimensional frame structure, in which method, in a first step, a two-dimensional grid structure. In this method, a linear semi-finished product can be provided as a continuous material. In this process, linear semi-finished products are arranged to form a two-dimensional grid structure such that they intersect at defined intersection points. For example, initially a first layer of linear semi-finished products can be arranged in which individual strip-shaped linear semi-finished products run in groups parallel to one another. Next, a second layer of linear semi-finished products extending parallel to each other in groups is placed on the first layer, wherein the linear semi-finished products are arranged at different angles relative to the linear semi-finished products in the first layer, so that The linear semi-finished products of intersect at the defined intersection points. The grid structure formed by strip-shaped linear semi-finished products initially not connected to each other may comprise a uniform pattern, but this is not required. In a further process step, the strip-shaped linear semi-finished products are subsequently connected to one another at intersection points. This connection can be achieved, for example, by point-contact heating in the region of the intersections, so that the semi-finished products are softened and adhere slightly to one another. In a subsequent further step associated with the method, the strip-shaped linear semifinished product is then softened so that it becomes somewhat tacky or viscous. This softening can be achieved, for example, by locally applying heat to the lattice structure along three imaginary non-intersecting straight lines. For example, the application of heat to a two-dimensional lattice structure can be performed along a first set of (imaginary) non-intersecting straight lines and correspondingly along a second set of (imaginary) non-intersecting straight lines, wherein the first set of straight lines and the second set of straight lines are connected to each other. extend alternately; in other words, in all cases, the straight lines of the second set lie between two straight lines of the first set, and the straight lines of the first set lie between two straight lines of the second set.

To subsequently impart the desired three-dimensional structure to the lattice structure, a force is introduced into the lattice structure along the middle of the imaginary lines to which heat is applied, thereby deforming the lattice structure out of its two-dimensional plane. Due to this deformation of the grid structure, the forces introduced are deflected into paired tensions acting on the semi-finished product, thus pulling said grid structure into the third dimension along the imaginary line in the middle to which heat is applied. This step resembles a deep drawing procedure in which the material of the semi-finished product is not stretched. Instead, it shortens in the plane as the lattice structure deforms into the third dimension. In order to prevent the grid structure from arbitrarily deviating when the force is introduced, the boundary of the grid structure or the straight lines on both sides of the middle line can be maintained by movable bearings, which ensures that the introduced force can be converted or decomposed into semi-finished products according to the target method tension in.

In the step of introducing force into the lattice structure, the two-dimensional lattice structure is deformed into a three-dimensional folded structure by successively and alternately forming crests and troughs. In this arrangement, the crests lie on the first set of straight lines and the deepest points of the troughs lie on the second set of straight lines. In this text, any term referring to peaks and troughs refers to a cross-sectional view of the resulting three-dimensional folded structure, where the peaks and troughs of the folded structure are evident. In perspective view, the peaks and troughs are elongated into "mountains" or ridges, with elongated "valleys" between them, when viewed relative to the surface of the grid structure. In this arrangement, the crests and troughs are produced by alternately introducing forces into the lattice structure in the direction of the desired highs and lows within the rectilinear regions of the two sets of straight lines. By introducing a force in the direction of the desired high and low points, the two-dimensional grid structure is deformed from the plane, thus creating the aforementioned mountains with valleys in between along the straight lines of the two sets of straight lines. Due to the forces exerted on the semi-finished product of the lattice structure, the two-dimensional lattice structure deforms from the plane along the straight lines of the two straight line groups, thus producing peaks and troughs in the desired manner. It should be noted that any reference to introducing a force into the lattice structure "along" a straight line means that the force is applied to the lattice structure in a generally perpendicular manner, the force being distributed along the straight line.

In order to carry out the method in an optimized manner with regard to the required time, the joining of the strip-shaped linear semi-finished products at the intersection points, the softening of the strip-shaped linear semi-finished products and the introduction of forces can be carried out in a continuous flow process, wherein the above-mentioned steps are carried out in Repetitive, performed in a continuous process carried out in the direction of production. In particular, it would be advantageous if the joining of strip-shaped linear semi-finished products was carried out while said products were softening, since due to this softening these products become somewhat tacky, i.e. slightly viscous, so that the semi-finished products placed on top of each other are easily glued to each other. Of course, the softening of the strip-shaped linear semi-finished products must take place in the region of the connection points, so that the strip-shaped linear semi-finished products are connected to each other in these regions. This continuously repeated production sequence is characterized by the production direction, in which heat is applied to another imaginary straight line of the lattice structure and a force is applied along these lines in order to deform the lattice structure.

To further optimize the fabrication procedure, force application was performed while applying heat to the lattice structure along three non-intersecting straight lines. As a result of this application of heat, the mesh structure can be plastically deformed in a targeted manner along the aforementioned straight line due to the introduction of force.

For reasons concerning statics and construction, if the intersection of strip-shaped linear semi-finished products in the third dimension forms the outer boundary of the three-dimensional frame structure to be produced, the application of heat is desirably performed in such a way that heat is always applied simultaneously to An intersection point in a direction perpendicular to the production direction. These intersections lying in a direction perpendicular to the production direction are adjacent intersections at which different linear semifinished products of the grid structure intersect. Since the force is always introduced into the grid structure along the middle of the three straight lines on which heat is applied to the grid structure, the deflection of the force due to the introduction of the force and due to the deformation of the grid structure to act on the semi-finished product Pairs of tension, thus the intersections to which heat has been applied are pulled into the desired third dimension, with which the intersections then form the outer boundaries of the three-dimensional frame structure in the third dimension.

As described above, during the simultaneous application of heat to the intersections located in the direction perpendicular to the production direction, it is possible to join the strip-shaped linear semi-finished products at the intersections. This is advantageous especially if the application of heat is such that the heat is applied simultaneously to the points of intersection lying in a direction perpendicular to the direction of production, since in this way the linear semi-finished products in the layers are in the area of the points of intersection become soft and are connected to each other due to their contact and, if applicable, due to the application of a corresponding force (eg gravity).

According to a particular aspect of the invention, a three-dimensional folded structure can be produced in such a way that, in a continuous and repeated procedure, a force is subsequently introduced into the lattice structure along each second imaginary line to which heat is applied, so that The said force pulls the half-finished product into the desired depth of the third dimension. In this procedure, the plane of the lattice structure is deformed so that the two straight lines on either side of the middle straight line to which heat is applied approach each other in the plane, thus producing a folded structure that has a hexagonal shape when viewed in cross section Accordion shape. It is of course also possible to force the lattice structure in the positive direction of the third dimension along each second line to which heat is applied, and each first, third, fifth, etc. line to which heat is applied is also in the third dimension A force is applied in the negative direction of , which also produces a zigzag folded structure.

When compared with the known methods of forming tools using lower and upper moulds, the method according to the invention is very flexible, thanks to the introduction of force along a straight line to which heat is applied, any desired particular thickness or Strength of the three-dimensional frame structure. For example, force and heat can be applied to the semi-finished product by means of edges that are movable into the third dimension and can be heated, wherein depending on the depth of penetration of the edges into the third dimension, frame structures of different thicknesses can be produced. Thus, for example, the thickness of the three-dimensional frame structure can be varied continuously, as long as the edges at different positions of the grid structure are moved into the third dimension to different extents in order to deform the grid structure.

In order to ensure a reliable connection of the strip-shaped linear semi-finished products at the intersection points, forces can already be introduced during the application of heat for softening the bar-shaped linear semi-finished products along the intersection points which lie in a direction perpendicular to the production direction, so that at the intersection points In the region of the points, small areas of compressed material occur on the linear semi-finished product, which as a positive effect makes it possible to increase the foldability of the semi-finished product at these points.

In the above paragraphs, a method for manufacturing a three-dimensional frame structure has been described wherein, in general, the straight lines along which the two-dimensional grid structure is folded do not intersect. However, in order to produce a three-dimensional grid structure that is as regular as possible, it is of course also possible to apply heat to the grid structure along parallel (imaginary) straight lines and to introduce forces into the grid structure at said straight line.

In order to facilitate the deformation of the two-dimensional lattice structure into the third dimension, in a further step the preformed depressions are embossed in the direction of the shaping that will subsequently be produced in the direction of the third dimension along the line to which heat is applied into semi-finished products. The embossing of the pre-formed recesses can be carried out in a completely separate step by means of a prismatic embossing tool specially provided for this purpose; as an alternative to this, the pre-formed recesses can also be carried out by means of movable and movable The heated edges are embossed into the semi-finished product. Since the strip-shaped linear semi-finished products in the layers intersect at the intersection points, the material thickness at these locations is similarly doubled. By embossing pre-formed recesses in the intersection point area, these thickenings can be reduced or in thermoplastic. The case of semi-finished products can even be completely eliminated. In particular, welding methods for connection can also be used in the case of thermoplastic semi-finished products.

In order to increase the force resistance of the three-dimensional frame structure produced in this way so that said frame structure is less reactive with respect to bending deformations, in a further step associated with the method the covering layer can be attached to— For example glued to - at least one side of the produced space frame structure such that the covering layer adjoins the furthest end of the corresponding side of the frame structure drawn into the third dimension. These covering layers thus absorb compressive and tensile forces due to the application of bending forces, so that the three-dimensional frame structure itself does not deform, or deforms only slightly, when subjected to bending forces. In order to make these claddings less susceptible to shear loads or to the associated shear deformations of the three-dimensional frame structure, and in particular to increase the shear loads that can be transmitted, in addition to the attachment described above, the claddings can be attached by means of a sewing procedure. Seamed to the distal-most ends of the respective sides of the frame structure, wherein in particular a one-sided seaming method may be used. As an alternative, the cover layer can also be fixed to the frame structure by the teeth of the positioning comb passing through the frame structure along Finally fixed in the overlay.

As shown in the above paragraphs, with the method for manufacturing a three-dimensional frame structure according to the present invention, when compared with the design using a rigid porous material as the core structure, because in the method according to the present invention there is no need to provide Such a rigid porous material can therefore achieve a reduction in the density of the core structure. Furthermore, with the method according to the invention it is possible to produce air-permeable structures, which are characterized in that they facilitate drainage, ie allow easy ventilation and drainage. Furthermore, due to the air-through design of the structure, it is certainly possible to place cables through the structure using artificial channels without causing any problems that compromise the mechanical integrity of said structure.

When compared with core structures using rigid porous materials, the three-dimensional framework structures produced by the method according to the invention are further characterized by a wide range of elastic deformations, so that there is no plastic deformation damage or only a small Small plastic deformation damage. Rather, the individual strips in the form of the folded linear semi-finished product can elastically sag when subjected to excessive loads, whereby improved resistance to damage can be achieved.

Since in the method according to the invention it is possible to use geometries of defined cross-section (triangular, quadrilateral, hexagonal, hollow, tubular, circular) formed by pultrusion, extrusion or continuous drawing, structural engineers Or the designer may further choose to vary the warpage behavior of individual strips of the three-dimensional frame structure so that by targeted selection of the defined frame geometry the properties of the core structure can be improved in a targeted manner.

Since the method can be implemented in a continuous flow process, by changing the speed of extrusion or pulling, and by changing the angle in the lattice structure, the formation of the slope, the difference in the density and thickness of the three-dimensional frame structure can be realized.

Because the lower and upper mold arrangements as known in the art are not used when folding the two-dimensional lattice structure to the third dimension, the flexibility of the procedure can be improved because when using the lower and upper molds, for Changing the folding angle and the height of the structure necessitates replacing the lower and upper molds. With the method according to the invention, such a change in the folding angle and the height of the structure can be realized with heatable edges, which can be shifted into the third dimension and which can be shifted in the third dimension to different positions. depth.

Description of drawings

Hereinafter, the present invention will be explained in more detail with reference to the accompanying drawings. It should be emphasized that the drawings provided are for the purpose of illustrating exemplary embodiments only and should not be construed as limiting the scope of protection in any way. Shown below:

Figure 1 shows a two-dimensional grid structure made of bar-shaped linear semi-finished products;

Figure 2 explains the embossing of preformed dimples into semi-finished products;

Figure 3 illustrates the introduction of forces into the grid structure to pull the grid structure into the third dimension;

Figure 4 shows the final product of the three-dimensional braced frame structure; and

Figure 5 illustrates the placement of cladding onto a three-dimensional frame structure.

Throughout the figures, the same reference numerals are used for identical or corresponding elements.

Detailed ways

Figure 1 shows a two-dimensional grid structure 1, which in the exemplary embodiment shown in the illustration is made of two sets of linear semi-finished products 2, wherein first the first set 2 is arranged such that the semi-finished products are placed in The first layers extend in parallel and are spaced apart from each other. Next a second group 3 of bar-shaped linear semi-finished products 3 is arranged on the first layer such that the individual bar-shaped linear semi-finished products 3 of the second group are parallel to each other and spaced from each other in a second layer above the first layer 2 Open way to extend. Due to this arrangement of the strip-shaped linear semi-finished products of the first group 2 and the second group 3 , a two-dimensional grid structure 1 is produced, wherein the individual strip-shaped linear semi-finished products in the two layers intersect at defined intersection points 4 .

Linear semi-finished products may for example consist of: pultruded (partially cross-linked) thermoset materials, extruded thermoplastic materials, continuously drawn metals or ceramics - especially precursor ceramics, where different cross-sections can be used geometric shapes.

In order to fix the shape of the grid structure produced in this way, so that for the next forming step, the strip-shaped linear semi-finished products of the two layers 2, 3 are connected to each other at the intersection point 4, for example, by applying heat and, if applicable, by The connection is carried out by applying a corresponding force along the straight lines 5, 6 shown in dotted lines in Fig. 1 . In this arrangement, the connection can be continuous and ordered in the production direction 7 . In this procedure, the points of intersection 4 running on the straight lines 5 , 6 that are substantially perpendicular to the production direction 7 are successively heated simultaneously in the production direction. Due to the applied heat, the linear semi-finished products are slightly heated at the intersection point 4 so that they become slightly tacky, ie sticky, and are thus connected to each other.

In a further step related to the method, the strip-shaped linear semi-finished products 2, 3 of the group along the three non-intersecting straight lines 5, 6 can then be softened, also for example by locally applying heat to the grid structure 1 to fulfill. Since the procedure for joining the strip-shaped linear semi-finished products at the intersection point 4 is already carried out with the application of heat, it is advantageous to combine the joining and softening of the strip-shaped linear semi-finished products in one step, so that the grid structure 1 is accordingly The softening of the three straight lines shown in dotted lines in FIG. 1 , which connect the intersection points 4 running in a direction perpendicular to the production direction 7 , softens.

In order to facilitate the shaping of the grid structure 1 in the third dimension in a subsequent deformation step, as shown in FIG. 2 , in an intermediate step, pre-shaped depressions can be embossed in the semi-finished product 2 , 3 . As shown schematically in FIG. 2 , small pits are embossed in the grid structure 1 , wherein the direction in which the pits 9 extend is the direction in which the grid structure 1 is then pulled into three dimensions. In this arrangement, the dimples 9 are evenly arranged on the aforementioned straight lines 5 , 6 along which heat has been applied to the grid structure 1 in order to soften the strip-shaped linear semi-finished products 2 , 3 . Since the softening of the strip-shaped linear semi-finished products 2, 3 is preferably carried out in such a way that heat is applied to the area of the intersection point 4 of these semi-finished products 2, 3, the following can be obtained due to the embossing of the above-mentioned pre-formed recesses 9: This means that the material thickening in the area of the intersection point 4 can be reduced or, in the case of thermoplastic semi-finished products, completely eliminated in the area of the intersection point 4 .

As shown in FIG. 3, in a further relevant step of the method, a force F is introduced into the lattice structure 1 along the middle of the three imaginary straight lines to which heat is applied, wherein the introduced force F causes the lattice structure 1 is deformed in the third dimension, which causes this introduced force F to be deflected into a pair of forces, as shown in the intermediate state in FIG. The decomposition of this force or this deflection is explained graphically in the parallelogram of the individual forces shown.In this way, tension is then introduced into the semi-finished product, along the middle line to which heat is applied, said Tension pulls the grid structure into the third dimension.

As further shown in FIG. 3 , along desired lines 5 , 6 , which will then represent the farthest ends of the three-dimensional frame structure, the grid structure is sandwiched between twin stringers 10 capable of simultaneously Realize three functions. These double stringers 10 are then made suitable for being heated and for being moved into the third dimension. In this way, the strip-shaped linear semi-finished products 2, 3 of the individual layers of the lattice structure 1 can be connected to each other by means of double stringers 10, provided that they act on the mesh along adjacent intersection points 4. Lattice structure 1. By heating the double stringers 10 , heat is then applied to the grid structure 1 or the intersections 4 , so that the strip-shaped linear semi-finished products 2 , 3 are softened and connected to each other at these points. The effect of connecting the bar-shaped linear semi-finished products 2, 3 at the intersection point 4 can additionally be supported, since the double stringers 10 are pressed together against each other, thus reducing, in an advantageous manner, the Undesirably thickened portions of the material. Furthermore, by pressing the double stringers 10 together, it is possible to emboss the preformed recesses 9 in the semi-finished product in the direction of the shaping that will subsequently take place in the direction of the third dimension, which facilitates Forming performed in 1. In order to finally be able to pull the grid structure into the third dimension, a force can be introduced into the grid structure by means of an edge 8, a double stringer 10 along the middle of the three straight lines 5, 6 to which heat has been applied, thus as shown in Fig. 3, the grid structure 1 is deformed into the third dimension due to the above-mentioned force decomposition. In order to be able to actually generate defined tensions F' and F" in the direction of the semi-finished product during the decomposition of the force, the double stringers 10 firmly clamp the grid structure along the two straight lines 5. However, in this In this arrangement, as indicated by the arrows in Figure 3, the double stringers 10 can be moved in the plane of the grid structure 1, so that due to the applied force F, the double stringers 10 move towards the direction of the middle line 6, or in the is pulled in said direction. In this procedure, the twin stringers 10 generate a reaction force against the displacement so that tensions F' and F" can be generated in a targeted manner.

As explained in the description above, the use of a movable and heatable double stringer arrangement 10 enables in a common step to achieve the connection of the linear semi-finished products at the intersection point 4, the softening of the strip-shaped linear semi-finished products 2, 3 and the introduction of force, when Viewed along the production direction 7 , the above-mentioned steps can be carried out consecutively and in a continuously repeated sequence.

The method according to the invention, wherein a force F is introduced into the lattice structure along the middle of the three straight lines 5, 6 to which heat is applied, is characterized in particular in that it is less severe than the known deformation procedure using a lower mold and an upper mold. Be flexible. Thus, with the method according to the invention it is possible to manufacture three-dimensional frame structures of varying density and thickness, since it is possible to move the double stringer arrangement 10 or the edge 8 to different depths in the third dimension, thanks to which the procedure makes it possible to influence three dimensions The thickness of the frame structure. It is therefore no longer necessary to complicately exchange the lower and upper mold arrangements in order to produce three-dimensional frame structures of different depths.

Figure 4 shows a three-dimensional frame structure manufactured using the method according to the invention. Through the deformation of the two-dimensional grid structure 1 shown in FIG. 1 , a periodically repeated three-dimensional grid structure including a plurality of quadrangular pyramids can be generated. In this arrangement, the apices of the pyramids are formed by the intersections 4 originally as two-dimensional lattice structures 1, due to the application of heat and the introduction of forces along the adjacent intersections 4, after the deformation procedure a laterally defined The most distal end of the three-dimensional frame structure. For illustrative purposes, FIG. 4 again shows three straight lines 5, 6 along which the original two-dimensional frame structure 1 is softened at the intersection 4 by locally applied temperature in order to be softened by applying temperature along it. The middle one of the straight lines of heat introduces force under the action of the grid structure, pulling the two-dimensional grid structure 1 into the third dimension.

Finally, FIG. 5 describes an optional step associated with the method in which a covering layer 11 is applied on both sides of the three-dimensional frame structure produced so that the covering layer 11 is supported by the points created by the pyramid tips. To attach the cladding 11 to the three-dimensional frame structure, the cladding can be glued to the tips of the pyramids. But, because the bonding surface of pyramid top is very little, shown by the suture line 12 that points out roughly in Fig. Properly use one side suture method.

Furthermore, it should be noted that "comprising" does not exclude other elements or steps, and "a" or "in" does not exclude a plurality. Furthermore, it should be pointed out that characteristics or steps which have been described with reference to one of the above exemplary embodiments may also be used in combination with other characteristics or steps in other exemplary embodiments described above. Reference signs in the claims should not be construed as limiting.

List of reference signs

1 Grid structure (two-dimensional)

2 strip linear semi-finished products (the first group, the first layer)

3 strip linear semi-finished products (second group, second layer)

4 intersections

5 straight lines (first set)

6 Straight lines (second set)

7 Production Direction

8 edges (removable, heatable)

9 Preformed pits

10 double stringers

11 Overlays

12 sutures

Claims (15)

1. a method that is used to make three-dimensional frame structure comprises the steps:

-produce two-dimensional grid structure (1) by the linear semi-finished product of bar shaped (2,3), locate to intersect in the crosspoint (4) that limits at semi-finished product (2,3) described in the described network (1);

-locate to connect the linear semi-finished product (2,3) of described bar shaped in described crosspoint (4);

-by along three non-cross linears (5,6) described network part being applied heat in all cases, make the linear semi-finished product of described bar shaped (2,3) softening;

Described network (1) is introduced with power (F) in-one of centre in the described straight line (5,6) that it is applied heat,

Wherein because the distortion of described network (1), the power of described introducing (F) be deflected into the paired tension force that acts on the described semi-finished product (2,3) (F ', F "); therefore straight line (5,6) is drawn in the third dimension with described network (1) in the middle of it is applied heat described.

2. the method for claim 1, wherein can in continuous continuous productive process, carry out in described crosspoint (4) and locate to connect the linear semi-finished product (2 of described bar shaped, 3), the linear semi-finished product (2 of softening described bar shaped, 3) and with power introduce, above-mentioned steps is to implement in the program of the continuous repetition that producer carries out on (7) in continuous continuous productive process.

3. method as claimed in claim 1 or 2 is wherein when described network (1) being carried out the introducing of power when applying heat along described three non-cross linears (5,6).

4. each described method in the claim is as described above wherein carried out applying of heat, makes heat be applied to simultaneously to be positioned at about the described crosspoint (4) of described producer on (7) vertical direction.

5. method as claimed in claim 4, wherein in that being applied to simultaneously, heat is positioned at perpendicular to described producer during the described crosspoint (4) on the direction of (7) and owing to heat is applied to simultaneously is positioned at perpendicular to the described crosspoint (4) of described producer on the direction of (7), carry out locating to connect the linear semi-finished product (2,3) of described bar shaped in described crosspoint (4).

6. each described method in the claim as described above, wherein in the program that repeats continuously, next along every second straight line (5 that it is applied heat, 6) power is introduced described network (1), described power is drawn in desired depth in the described third dimension with described semi-finished product, therefore generates the three dimensional fold structure.

7. each described method in the claim as described above wherein is applied to described semi-finished product (2,3) by means of the seamed edge that can move into the described third dimension and can heat (8) with power and heat.

8. method as claimed in claim 7, wherein with described edge (8) thus move to the different-thickness that different depth in the described third dimension generates described frame structure.

9. as each described method in the claim 4 to 8, wherein be used for softening the linear semi-finished product (2 of described bar shaped applying heat along being positioned at about the described crosspoint (4) of described producer on (7) vertical direction, 3) during power is introduced, therefore carry out locating to connect the linear semi-finished product (2,3) of described bar shaped in described crosspoint (4).

10. each described method in the claim as described above wherein carries out the heat of described network (1) is applied along parallel lines (5,6).

11. each described method in the claim as described above comprises further step:

-along the described straight line (5,6) that it is applied heat, on the direction of the shaping that produces on subsequently will direction preform pit (9) is impressed in the described semi-finished product (2,3) in the third dimension.

12. each described method in the claim as described above comprises further step:

-cover layer (11) is attached at least one side of the three-dimensional frame structure of being produced, make the distal-most end adjacency that is drawn into the described third dimension of respective side of described cover layer (11) and described frame structure.

13. the method for claim 1 is wherein closed the distal-most end that method (12) is attached to cover layer the respective side of described frame structure by a latasuture.

14. a support frame structure that is used for sandwich structure, wherein said support frame structure is made according to a described method in the claim 1 to 13.

15. an aircraft that comprises the structure member of sandwich structure form, the cored structure of described sandwich structure utilize in the claim 1 to 13 each described method to make.

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