WO1998052705A1

WO1998052705A1 - Three-dimensional lattice structure and method and device for producing the same

Info

Publication number: WO1998052705A1
Application number: PCT/EP1998/002896
Authority: WO
Inventors: Jon Priluck; Matti I. Williams
Original assignee: Jonathan Aerospace Materials Europe Ab; Jonathan Aerospace Materials Corporation
Priority date: 1997-05-23
Filing date: 1998-05-16
Publication date: 1998-11-26
Also published as: TW376339B; ZA984076B; DE19721586A1; AU7913198A; AR012721A1

Abstract

The invention relates to a three-dimensional lattice structure consisting at least predominantly of triangles. Said triangles are preferably joined rigidly at their respective corners so as to create a three-dimensional structure. The invention also relates to methods and devices for producing a corresponding three-dimensional lattice structure. The aim of the invention is to improve and supplement the actual form of lattice structures of this type and the methods and devices used to produce them, and to produce lattice structures to cover a middle size range between lattice structures made from very small, fine and short wires or wires which are bent short, and known support lattice-work. To this end, the inventive structure is produced by means of casting, injection-moulding or diecasting, permanent joining of level and/or corrugated or folded two-dimensional lattices, for example by welding or sticking, by means of layered construction, for example by stereolithography, by layering existing three-dimensional lattice structures or by any combination of these methods.

Description

Three-dimensional lattice structure and method and device for its production

The present invention relates to a three-dimensional lattice structure which consists at least predominantly of triangles which are preferably firmly connected to one another at their respective corners and thus span a spatial structure.

The present invention also relates to methods and devices for producing a corresponding three-dimensional lattice structure.

Three-dimensional lattice structures, which consist predominantly or exclusively of triangles, which are connected at their corners, have long been known, for. B. in the form of so-called lattice support structures or girders, which are used as ceiling beams or ceiling structures in buildings. Such lattice girders or lattice support structures combine the advantages of a relatively low weight with a relatively high load capacity.

However, it has not yet been possible to use corresponding lattice structure materials on a small scale, i.e. for relatively small or very thin components, such as B. sheets, spars, cross members and other such parts such as z. B. in motor vehicle construction and also in aircraft construction use, in vehicle and aircraft construction generally sufficiently thick sheets, hollow components, solid supports or composite materials are used to produce parts that can withstand the loads that occur. These parts often require a great deal of mass in order to be able to provide the desired strength and have a correspondingly high weight.

The conventional manufacture of lattice structures, such as. B. find use in building construction, and in which every single bar of a lattice structure is screwed or welded to the other bars, would be far too expensive for the usual mass production in vehicle and aircraft construction and in view of the small size of the parts often used, because at the size of the parts used in vehicle construction, the individual grid elements, specifically the triangles and sides of the triangle, should be relatively small, which in turn means large parts with a large number of punctiform connections that were previously not economically feasible with conventional methods. It goes without saying that the areas of vehicle and aircraft construction are only mentioned here by way of example and that there are of course other areas in which, for example, sheets or spars or in general parts that have relatively small dimensions in at least one dimension would be advantageous , if they could combine a high load-bearing capacity and bending strength with a low weight and small dimensions. But even for larger dimensioned parts, as they are known in principle, there is still a need to simplify corresponding manufacturing processes, or to make these processes cheaper and more effective.

The applicants of the present invention have already in the international patent application with the publication no. WO97 / 04897 discloses a lattice structure and methods for its production, which take into account the needs for corresponding lattice structure materials with dimensions that are at least one dimension small, light weight and high load-bearing capacity or bending strength.

Compared to this prior art, it is the object of the present invention to further supplement and perfect the concrete structure of such lattice structures and methods and devices for their production. Among other things, it is also a matter of producing lattice structures of a size which on the one hand cover a central region between lattice structures which are produced from very small, fine and short or short angled wires and on the other hand the known lattice structures.

With regard to the three-dimensional lattice structure itself, the object on which the invention is based is achieved in that the structure is connected by casting, injection molding or die casting, by means of a fixed connection, such as, for example, welding or gluing, flat and / or corrugated or folded two-dimensional lattice, or else by building up in layers , such as by stereolithography, by coating existing three-dimensional lattice structures, or any combination of the above methods.

Essentially, two different types of three-dimensional lattice structures are particularly preferred, namely a first type that is at least partially made of metal and a second type that is not made of metal, but is made, for example, of ceramic or also of wax or plastic. The last-mentioned type of three-dimensional lattice structure is preferably used as a molded and coating object and in this respect has the function of an intermediate product from which a generally metallic or at least partially metallic lattice structure is ultimately produced. However, it is not excluded, also to use these lattice structures, especially if they are made of plastic, as the corresponding carrier materials, such a lattice structure made of plastic having the advantage of a lower thermal conductivity and electrical insulation capability than metal. Hybrid or composite materials, such as a metal-ceramic composite, glass fiber or carbon fiber reinforced plastics, are also suitable for the production of corresponding lattice structures.

An embodiment of the three-dimensional lattice structure is particularly preferred, in which all the linear elements defining the triangle sides form at least five different groups, the elements of a group being defined in that they each run parallel to one another. In contrast, the elements of different groups run at an angle to each other. The essentially linear elements can sometimes also span rectangular or trapezoidal shapes or general square shapes.

A variant is preferred, a sixth group of parallel elements also being provided which enclose an angle of more than zero degrees with the other elements.

For example, a folded grid can essentially consist of equilateral or isosceles triangles or rhombuses and be covered by a flat square or rectangular grid at the top and bottom, with the intersection or corner points of the squares or rectangles with the corner points of the diamonds or triangles coincide in the upper and lower node level of the folded lattice and are connected there with the folded lattice, and the rectangular or square lattices of the flat lattices are additionally provided with at least one diagonal bracing.

In the context of the present description, the terms “folded” or “fold” include not only sharp-edged but also rounded, more or less wavy structures.

The triangles, from which the structure as a whole is made up, lie in a total of five different planes inclined relative to one another or in five different groups of planes with planes parallel within each group.

As the example of a folded diamond grid or triangular grid shows, in the case of the diamonds the fold lines run along diagonals of the diamonds and in the case of triangles the fold lines run along parallel sides of the triangle, and the folded lattices are covered by a rectangular or square lattice on the top and bottom, so that the structure does not necessarily have to be composed exclusively of triangles, since the upper and lower levels, as already mentioned, consist of can consist of a rectangular grid. However, this can be supplemented by providing a diagonal connection in each of the rectangles to form a lattice of equilateral triangles, so that the entire lattice structure is then composed exclusively of triangles. As is known, it can be assumed that triangles have a stable spatial structure mainly because the angles between the individual sides of the triangle can only be changed if the length of the sides of the triangle is changed at the same time. This is countered by the tensile and compressive stress forces occurring in the individual side elements, so that structures composed of triangles are very dimensionally stable. The three-dimensional stability is achieved above all in that the triangles or triangle sides are connected to one another in such a way that tetrahedral or pyramid shapes are spanned in the lattice structure, so that the deformation resistance of the triangles is effective in every spatial direction

Particular embodiments of the present invention do not differ in principle from the previously described embodiments, but modify them slightly, e.g. B. some of the triangular elements are curved or, in the structures described above, linearly running along a straight line, individual triangular sides or lattice elements each enclose a small angle with the preceding and the following element, so that they define an arc of curvature overall. If this happens in parallel with several series of linear triangular sides, the lattice structure described above, which is also essentially composed of flat layers, is only modified in such a way that it is now delimited by surfaces which are at least partially curved in space. Viewed on a small scale, such curved lattice structures are practically no different from the flat lattice structures, since the angles between closely adjacent triangle sides, which are aligned parallel or along a straight line in the case of exactly flat lattice structures, are very small and only become clearer over larger distances. The mechanical properties of such a lattice structure therefore do not differ significantly from the flat lattice structures. The spatial lattice structures delimited by curved surfaces can best be imagined to be made from lattice structures that have the above-described, flat layer structure of flat and folded layers and that are deformed over a large area and uniformly, the deformation being uniform on each individual triangular cell on the other deformation involved grid structure elements are distributed. Each individual triangle is then only very slightly deformed compared to the corresponding triangle in a flat lattice structure, but the small deformations of adjacent triangles add up over a large number of triangles, so that the deformation is clearly visible and many arbitrary shapes can be produced thereby. The radii of curvature of the deformation are large compared to the length of the sides of the elementary triangles from which the lattice structure is built.

For the rest, however, the lattice structures according to the invention can also have sharp angled portions, in particular around angles that can be obtained or combined anyway between the triangles or planes from linear elements of the structure. For some applications, an embodiment of the invention is particularly preferred in which the individual sides of the triangle are formed from hollow, tubular elements. It goes without saying that these hollow, tubular elements are preferably all connected to one another, so that the interior of such a lattice structure material can also be used for the passage of liquids or gases. At the same time and in addition to the weight saving, which is already achieved in that the entire structure is composed only of individual, essentially rod-shaped elements that span a spatial grid, and thus has a very low density and a correspondingly low weight, that will The weight of the structure is further reduced by the fact that the individual rod elements are also hollow.

These hollow, tubular elements can then, as already mentioned, serve as transport routes for liquids or gases, and they can also be filled with another material, which is preferably lighter than the material from which the tubular elements are made, by a total of one more to get effective weight savings. It can also be expedient if the tube material chemically or physically combines with the filling material. For example, the filler material can be porous, and the pipe material subsequently applied to the filler material can penetrate into these pores and thus establish a close connection with the filler material.

According to another embodiment, the three-dimensional lattice structure consists of a casting material, it being understood that such a structure consisting of casting material has been produced by pouring the material into a corresponding hollow mold.

Regarding the folded grid, it is e.g. B. possible, the size or height, possibly also the angles, the triangles or diamonds from which the folded grid is formed to continuously enlarge at least in one direction, namely in the direction transverse to the fold lines, so that either the fold height or the fold distance or both must correspondingly increase continuously. If the fold spacing is kept constant, the upper and lower levels of the folded grid no longer run parallel, but inclined at a small angle to each other. Such wedge-shaped lattice structure elements are also the subject of the present invention. The diamond or triangular shape and size can continuously change again in the opposite direction, so that, for example, a structure tapering on two sides is created. In connection with the deformation or the production in the deformed state, a large number of differently shaped components and elements can be produced from the lattice structures according to the invention. So you can z. B. twist the boundary planes of a flat, planar lattice structure material in principle, so that the boundary planes run along screw surfaces. The lattice structures can also be delimited by part-circular or cylindrical walls.

With regard to the method for producing a three-dimensional lattice structure, which consists at least predominantly of triangles, which are preferably firmly connected to one another at their respective corners and thus span a spatial structure, the object on which the invention is based is achieved according to one embodiment in that the structure is cast in a hollow mold, preferably made of molding sand.

According to a further alternative method for producing a corresponding three-dimensional lattice structure, it is proposed according to the invention that a model of the lattice structure is produced and the model is coated with the material from which the lattice structure is later to be at least partially made. This method leads to the previously described variant of a lattice structure, in which the individual elements which form the triangular sides consist of hollow, tubular parts which are filled with the material of the model. This variant of the manufacturing method according to the invention has the advantage that a material can be selected for the model, which makes the production of the model particularly simple without the mechanical strength and load-bearing capacity of the model being important, since this is only achieved subsequently by the coating material , Alternatively, this coating material can also be molding sand, which means that the model is a first positive, which is used to produce the negative mold consisting of molding sand.

It is therefore expedient if, in a first step, a model of the lattice is made of a meltable compared to the final material of the lattice structure and in the liquid Condition good flowable material is produced. If necessary, a corresponding shape can also be evacuated in order to facilitate the flowing in or sucking in of the material. You can then use such a model. B. in a reusable metal mold and then coat in the desired manner, while the final material of the lattice structure in a comparable shape would not be easily produced because it z. B. would have a much too high melting temperature or would form a connection with the material of the mold.

A model and a resulting complete lattice structure can also be constructed from two identical basic structure elements, each of these basic structure elements consisting of parallel and essentially one-dimensional elements which are connected to one another by a further group of parallel, essentially one-dimensional elements which, however, are folded in a zigzag pattern and protrude from the plane of the first-mentioned elements and are only connected to one of the first parallel elements with every second corner. The zigzag-shaped elements and the linear elements expediently form an angle of 45 ° with one another in the plan view. One can then turn a second, identical basic structural element with respect to the former by 180 ° and place one into the other with the mutually facing projecting corners of the jagged pattern, so that the protruding corners of the jagged pattern of one grid engage in the valleys between the projecting corners of the other pattern, which already on the other hand are connected to the linear elements. Such a lattice structure is then still very compliant with respect to bends around an axis parallel to the linear elements, but this property can be advantageously used for the production of cylindrical or tubular or also partially cylindrical lattice structures by causing deformation about such an axis and stiffeners running in the circumferential direction, eg. in the form of parallel strips or in the form of a triangular grid or rectangular grid, and if appropriate also in the form of plates or foils or a combination of these elements, are only attached to the outside and / or the inside of such a cylindrical or semi-cylindrical element after they have been deformed .

Even in the case of flat lattice structures, the parallel rectilinear elements can of course also be supplemented by transverse struts to form rectangles or triangles after the production of such a lattice structure.

Alternatively, models can also be constructed from two different basic structures, with such a basic structure either in the preferred embodiment of the invention consists of a diamond grid, which is mutually folded along fold lines, which are defined by the parallel (shorter) diagonals of the diamonds. However, additional connecting elements can also be provided along these diamond diagonals, so that overall there is a triangular grid, which is then folded along exactly the same folding lines as the diamond grid, with the difference that triangular sides now also run along these folding lines. The diamonds or triangles are preferably equilateral diamonds or isosceles triangles with basically any angle between the sides.

In addition to this folded triangular or diamond grid, a rectangular grid, e.g. B. a square grid, which, however, may have additional diagonal connections in the rectangles or squares, so that overall there is a grid of right-angled triangles, each complementing a rectangle or square. The grid spacing in the rectangular grid is dimensioned so that it exactly matches the fold spacing of the folded grid, and in addition the short diagonal of the diamond grid or the corresponding side of the triangular grid has exactly the dimension of one of the sides of the rectangle or square. Accordingly, the folded lattice can be placed on such a rectangular lattice in such a way that the in-plane corners of the rhombuses or corner points of triangles coincide exactly with the lattice points of the rectangular lattice, and the parts can be connected to one another in this position. A corresponding rectangular grid can also be placed on the other side and connected to the tips of the diamond grid or triangular grid. Then, if necessary, other alternating layers of folded diamond or triangular grids and flat rectangular grids can be placed and connected to the previous layers.

However, it is also possible to connect the nodes of a partial lattice with the sides of triangles, rhombuses or rectangles of another partial lattice or only the sides of these basic structural elements, which in turn can create new nodes.

The forms of a folded grid and a rectangular grid (with diagonal bracing) can be worked out in corresponding metal blocks, which serve as casting molds for model mass. Alternatively, a model can also be produced by building up in layers, such as stereolithography. Such a model is built up in layers by immersing a support in a light-sensitive substance and then locally curing it by targeted local irradiation with a laser beam. The dipping and curing process is repeated many times so that layer by layer of the photosensitive, cured material is exposed on the underlying one Layers until finally the entire model is built up in layers. It is understood that such a laser beam preferably simulates the desired structure under computer control. Even though this method is relatively complex and models or finished lattice structures can only be produced very slowly in this way, it nevertheless opens up the possibility of realizing very complicated geometries from lattice structures, in particular all types of more or less curved and deformed lattice structures . After the corresponding models have been completed, the final lattice structures can be produced in various ways. According to a first variant, the model is encased in a conventional manner with molding sand, optionally also surface-treated for this purpose and also immersed in liquids, and then the molding sand shell is sintered, and in the process or before, the model mass is liquefied, burned or otherwise gasified and thereby removed from the mold away. The resulting hollow mold made of molding sand can then be poured out with the lattice structure material.

Alternatively, however, the model can also be coated with the material finally provided for the lattice structure. This can e.g. B. by immersing the model in a liquid bath containing the material of the lattice structure or components thereof.

In addition, there are of course other coating methods, such as. B. chemical or physical vapor deposition (CVD or PVD). The model mass can possibly also be coated electrostatically if it is electrically conductive. For this purpose, the model can also initially be given a thin, electrically conductive coating, which then enables the electrostatic coating. The model can also be sprayed or painted. In this context, it can also be expedient if the model material is porous at least on its surface, so that it forms a firm connection with applied coating materials. However, the material properties of model material and coating material can also be selected so that the model material enters into a physical or chemical connection with the coating material.

The two aforementioned methods are closely related to one another, because in both cases a model of the grid structure is at least preferably first produced, which is then coated. In the one case, the coating material is the desired material from which the finished lattice structure should at least partially consist, in the other case the coating material is a molding material such as molding sand, optionally mixed with additives and binders, and after drying, The model material is then removed from the hollow mold when it hardens. The molding material can be fired or sintered before or after the removal of the pattern material in order to obtain a sufficiently firm shape. In the case of coating with a material provided for the lattice structure, the modeling material can optionally be left in the hollow structure of the individual lattice rod elements or, as in the case of mold production, can be removed from the lattice structure, generally by heating and thus liquefying.

After the structure has been completed, the material of the lattice structure can also be physically or chemically aftertreated. For example, you can paint the lattice structure material or provide it with a chemical corrosion protection layer. Both can e.g. B. in an immersion bath.

In a special method for producing a three-dimensional lattice structure of the type in question, it is proposed according to the invention that the structure is produced by welding flat and folded lattices, a folded lattice being placed in alignment with a flat lattice, a welding electrode on the outside of the flat lattice abuts and an opposite electrode engages in one of the folds of the folded grid. It goes without saying that the electrode engaging in the folds of the grid must not destroy or damage the folds and must accordingly have a suitable shape with a correspondingly narrow profile.

The electrode is preferably designed as a wedge-shaped electrode, which can extend at least over a section of the length of the fold, but in the case of narrow lattice structures also over the entire length of the fold, in another embodiment of the invention, which is even more preferred the electrode engaging in the folds is designed as a rolling electrode, the roller having a wedge-shaped cross section or a wedge-shaped profile which can engage with the outer edge in the cross-sectionally substantially V-shaped folds of the folded grid.

The opposite electrode, in particular if it supports a flat grid that is welded to the folded grid, can be designed as a large, flat electrode that offers a support surface for the wedge electrode or the roll electrode over the entire length of the fold, if at least supports the wedge-shaped electrode or rolling electrode over the entire contact area. The folded grid and the flat grid are clamped between the two electrodes, and if one is exceeded A certain contact pressure causes a current to flow, which leads to the welding of the flat and the folded grid. The two grids are aligned so that the nodes of the flat grid coincide with the diamond tips or triangular corners of the folded grid.

The flat grids, like the folded grids, preferably consist of perforated sheet materials, and the holes are either triangular or diamond-shaped, depending on the shape of the basic elements of the grating structure, but can also have other shapes.

The perforated sheets can be produced either by punching out the holes or by etching techniques, optionally also by laser cutting or by cutting with a pulsed high pressure water jet or other effective techniques. What is essential for the perforated sheet metal materials and also for all other basic elements from which the lattice structure according to the invention is to be produced is above all good dimensional accuracy and accuracy, so that after the folding and folding of folded and flat lattices, the nodes or corner points of the triangles as far as possible the folded lattice and the flat lattice actually coincide or at least nodes with sides of basic structure elements, such as triangles and / or diamonds, can coincide and be connected to one another.

The devices for the production of corresponding lattice structure materials primarily include folding devices for the production of folded lattices from flat perforated sheets or for example also welded wire structures or woven fabrics, associated alignment and feed devices and finally also welding devices with the aid of which flat lattices and folded lattices are precise and largely can be automatically welded together.

Such a device according to the present invention, which is provided for welding flat and folded grids, has a narrow profile, z. B. wedge-shaped, electrode or a roller-shaped electrode with a corresponding z. B. wedge-shaped, roller profile, which is mainly and essentially designed so that it engages in the bottom of the folds of the folded grid and press the folded grid along the respective fold line against the further grid and welded to it, with a counter electrode is provided which supports this further grid. The counter electrode is either flat or convex, for example like a cylinder surface but also also be narrow or wedge-shaped, in particular if a further folded grid is also provided on the other side of the first folded grid and is to be connected to it, an intermediate layer in the form of a flat grid also being able to be present.

For the processing of corresponding perforated sheets or wire structures, a positioning device is also important which aligns the two grids to be welded to one another relative to one another and also with respect to any welding electrodes, so that the welding takes place at the respective grid nodes. Such a positioning device can, for. B. have pins which engage in the perforations of the perforated sheets and / or wedge-shaped elements which engage in a precise fit in the fold profile of a folded grid. The welding device can be supplemented by a corresponding feed device which moves the folded grid and the flat grid forward by exactly one fold distance after each welding process.

However, an embodiment of the invention is particularly preferred in which two or more welding electrodes are arranged next to one another and e.g. B. intervene at a distance of 3 or even 10 or more folds in the respective folded lattice and, if possible, weld the lattice node points there, if not necessarily, to the node points of the underlying rectangular network or lattice. In such a variant with, for example, two rolling electrodes, it is expedient if the two electrodes have an odd fold spacing from one another, while the feed device moves the folded grid and the flat grid forward by two fold spacings after each welding operation. The first welding electrode then welds every second fold, and the remaining electrode later welds the intermediate fold that had not yet been welded by the first electrode. It is understood that this principle can also be extended to a larger number of electrodes, so that, for. B. three electrodes can be provided, each having a four-fold distance or multiple times a four-fold distance from each other, while after each welding operation the folded grid and the flat grid are moved three fold distances each.

A lattice structure can also be produced from perforated sheet material or lattices arranged in at least two layers, the layers being connected to one another according to a predetermined pattern of connection points and being moved apart between the connection points to a larger layer distance. Further advantages, features and possible uses of the present invention will become clear from the following description of preferred embodiments and the associated figures.

Show it

FIG. 1 shows a diamond grid with a few fold lines indicated by dashed lines,

FIG. 2 shows the diamond mesh according to FIG. 1 in a partially flat and partially folded state,

2a shows the diamond mesh according to FIG. 2 in a fully folded state

FIG. 3 shows a grid composed of squares or equilateral triangles for the connection to the fold grid,

FIG. 4 shows a diamond grid with a different orientation in a partially flat and partially folded state,

5 shows a rectangular grid similar to FIG. 3, but in a different orientation and for connection to the folded grid according to FIG. 4,

6 shows a spatial lattice structure made of elements according to FIGS. 1 to 3 from two folded and three flat layers in three different ones

Views, Figure 7 schematically shows the configuration of a single sub-lattice, which can be assembled with an identical sub-lattice to a finished lattice structure, Figure 8 is a perspective view of a lattice with the structure of the lattice structure according to Figure 6, Figure 9 is a lattice structure curved around an axis of the same basic structure like the structure according to FIG. 8, FIG. 10 is a perspective view of a wedge-shaped lattice structure, in which the angle and height of the triangles from which the structure is built change continuously in one direction, FIG. 11 is a perspective view of a lattice structure that is twisted in itself on the

8, FIG. 12 a structure similar to FIG. 9, but with end flanges attached to the end faces of the lattice structure, FIG. 13 a structure similar to the embodiment according to FIG. 10, also provided with end flanges, FIG. 14 an essentially two-dimensional shape simulating a partial sphere

Lattice structure, FIG. 1 5 shows a manufacturing principle for a simplified lattice, Figure 16 schematically shows a further method for producing inventive

Lattice structures by folding flat, preferably perforated sheets, FIG. 17 schematically shows a folding device for bending material and

Figure 1 8 shows a feed and welding device for the connection of folded with flat grid material.

In Figure 1 you can see a diamond-shaped grid 10 which z. B. can be made by punching or etching diamond-shaped openings from a sheet. The specifically chosen representation is not necessarily true to scale; in particular, the present invention is also intended to produce lattice structures in which the dimensions of the individual lattice bars, which are defined here by one of the diamond sides, are still significantly smaller, and which are made of rod-shaped elements with a rectangular shape or also a round cross-section of diamond sides that are possibly also significantly thinner or thicker. In addition, it goes without saying that the structure shown can be continued as far as desired in the plane, a fixed width being generally chosen for the material and otherwise rolled strip material being used, that is to say the objects in question being produced with a fixed width and any length.

In Figure 1, some of the fold lines are with dotted lines d- _| to d ₄ , wherein the same sheet with diamond-shaped openings can be seen again in FIG. 2, but in which the folding has already taken place along approximately half of the folding lines. As a result of the folding, the individual sides of the rhombuses appear as squares in plan view in the upper part of FIG. 2. It should be noted, however, that along the diagonals d ₁ shown in dashed lines all the corner points of these squares lie in a valley of the folds, i.e. behind the paper plane, while the points along the diagonals d lie on the raised ridges of the folds, i.e. in front of the paper plane, when the paper plane defines a middle plane between the highest and lowest string points.

Figure 2a shows the finished folded sheet metal strip 10 in a perspective view.

When comparing with FIG. 3, it can be seen that the corner points of the smallest squares of the flat grid in FIG. 3 coincide exactly with the top corners of the diamond tips of the folded grid and after a shift by half a diagonal of the squares with the corner points of the diamonds in the lower one Plane of the folded grid collapse. After welding, the diamond sides then form triangles together with the base sides of the squares of the flat grids, and the squares themselves are also shown by the in Diagonals running in the longitudinal direction are supplemented to form right-angled triangles, so that the entire finished structure is composed exclusively of triangles as basic elements. The position of one of the squares of the planar lattice is again indicated with thinner lines in the folded lattice to facilitate understanding.

Since the fold lines are not perpendicular to the longitudinal direction of the strip shown in FIG. 1, the folded sheet of the sheet material kinks laterally by a small angle, which in the present case is 15 °.

The selected spatial orientation of the diamonds in the example of FIGS. 1 to 3 has the advantage, however, that both the folded grid and the flat square grid (supplemented by right-angled triangles) each have straight, lateral outer edges. Another variant of the diamond grid is shown in FIG. 4, which differs from the embodiment according to FIGS. 1 and 2 only in that the diamonds have a different orientation with respect to the longitudinal direction of the respective sheet metal material strip, so that the fold lines run exactly perpendicular to the longitudinal extension of the strip . The strip in question can be seen in FIG. 4 both in a partially flat state and in the folded state. However, as can be seen, this causes the side edges of this strip to zigzag. This can be avoided if necessary by providing the two right and left edges with an additional straight element, as shown on the left side in FIG. The corresponding square grid, which can be placed on the folded grid according to FIG. 4, is shown in FIG. 5. It should be noted that, in the folded grid in FIG. 4, the corner points of the small squares that can be seen there again lie in different planes, so that the diagonals of these small squares, again drawn in dashed lines at one point, correspond to the side edges of the squares in FIG. 5, the corner points of which the corresponding diamond tips are connected.

For automated, mechanical production, it can be advantageous if a strip consisting of a long, wound web material retains its previous orientation as shown in FIG. 4 after folding, so that it can be processed continuously in a processing line.

6 shows in three different plan views a lattice structure material which is made up of basic elements according to FIGS. 1 to 3. There are two folded layers according to FIGS. 1 and 2 with one in between and two outside lying flat grid layers according to Figure 3 welded together or this structure is cast from a single piece. For example, a wax model of the lattice structures according to FIGS. 1 or 2 and 3 can first be produced and the wax model is then welded in a corresponding manner to the final lattice structure. The wax material is then coated in the usual manner with molding sand, which is then dried, sintered and / or hardened so that the wax can be baked out of the hollow mold. The hollow mold is then poured out with a metal, for example, and the molding material is then chipped off or blasted. The resulting structure corresponds to that of the previously produced model, that is to say, in the present example, the structure shown in the various views according to FIG.

A variant is shown in FIG. 7, which is constructed from only a single basic type of a basic structure 10 '. The basic structure 10 ′ consists of a square grid made of parallel wires or strips 1, with zigzag wires 2 parallel to one another also extending in a plane perpendicular to the plane spanned by the square grid 1. To clarify the position of the planes of the zigzag lines, one of these planes is highlighted in the upper and middle part of FIG. 1 by hatching. The angles of inclination and spacing of the individual elements 1, 2 are coordinated with one another in such a way that an identical basic structure 10 'after turning 1 80 °, as indicated by arrow II, fits exactly with another, not rotated lattice structure 10 ', the tips 3 of the zigzag lines protruding from the plane of the elements 1 each engaging in the valley 5 of the zigzag lines of the opposite pattern .

This results in the spatial lattice structure shown below in FIG. 7, which essentially corresponds to the structure in accordance with FIG. 2, the stripes 1 of the square lattice also containing the tips of the triangles or pyramids formed from the elements 2 in the upper under connect the lower level. Additional struts can then also be provided diagonally, so that the overall plan view would be the same as that shown, for example, in FIG. 6. The difference to the embodiment according to FIG. 6 would then essentially consist in the fact that the variant of a lattice structure produced according to FIG. 7 only consists of three layers, namely two flat layers and a folded layer arranged between them, even if the structure does not consist of three different layers is produced, but only from a single basic structural element 10 '. However, the edge regions of the basic structural elements 10 'and also of the fully assembled lattice structure are not shown in their final form in FIG it is only about the representation of the principle of clarifying the manufacture of a finished lattice structure from two identical basic structure elements, the edges being able to be subsequently worked on, edged or left in the resulting asymmetrical shape.

For certain applications it can also be useful if - at least initially - neither transverse nor diagonal struts are provided in the flat layers of elements 1, but only parallel strips 1, which are only held together by zigzag elements 2, because then the corresponding structure is easily bendable about an axis that runs parallel to the elements 1, the cross struts to increase the rigidity of the entire structure being attached, for example, only after bending about a corresponding axis. In this way, one could, for example, manufacture the structures to be described according to FIGS. 9, 11 and 12. It goes without saying that several of the elements shown at the bottom right in FIG. 7 can also be placed on top of one another and connected to one another, the elements 1 of one lattice structure being arranged either parallel to those of the other or perpendicular to them.

FIG. 8 shows a lattice structure according to the invention which, apart from the external dimensions, corresponds to the lattice structure shown in FIG. 6. However, the lattice structure in FIG. 8 is shown in perspective.

FIG. 9 shows a further structure which, apart from a curvature about an axis (not shown), corresponds to the structure of FIG. 8. However, while in the embodiment according to FIG. 8 the individual triangles are formed by only a few groups of mutually parallel sides, in the embodiment according to FIG. 9 only the triangular sides of a group which are respectively arranged at the same angle with respect to the bending axis are parallel to one another. However, the parallelism of the triangle sides belonging to a group of parallel elements in FIG. 8 is still largely retained in FIG. 9, at least for triangles lying close together, since the radius of curvature of the overall structure is relatively large compared to the length of the individual triangle sides. The mechanical deformation resistance is therefore essentially the same for the curved structure as for the flat structure shown in FIG.

In the embodiment according to FIG. 10, in the two inner layers, which can be thought of as folded structures as shown in FIG. 2b, the folding angle increases continuously from the left end of FIG. 10 to the right, so that the height of the triangles recognizable in the side view also increases continuously. In addition, the width of the structure increases continuously from left to right, which is achieved by correspondingly extending the transverse sides of the triangle. In this way, the result is a wedge-shaped lattice structure.

FIG. 11 shows a further structure which is closely related to the structure shown in FIG. 8 and only shows a torsion with respect to a screw axis running in the longitudinal direction of the lattice structure. It goes without saying that such a structure with torsional distortion is generally not produced directly from the finished, flat structure according to FIG. 8, but rather that the twisted structure with the aid of corresponding casting molds, by firmly connecting partial grids in the twisted orientation, is produced directly in this form by coating a corresponding model or by layered construction, so that this form has maximum stability. For many embodiments of the lattice structure and the corresponding production methods, it is essential that a lattice structure composed of stable basic elements or partial lattices is not deformed after the fixed connection or assembly, but that any deformation processes to produce complex final shapes before the partial lattices are connected, the casting or the coating of corresponding models.

Figure 1 2 shows an embodiment very related to Figure 9, in which only the two ends of the lattice structure according to Figure 8 are provided with end caps or flanges which have mounting holes.

Figure 1 3 shows a variant corresponding to Figure 10, in which the ends are also provided with end flanges which have fastening bores. It goes without saying that the embodiments according to FIGS. 8 and 11 as well as all other embodiments can have corresponding fastening flanges.

FIG. 14 shows a further, spatially curved element, with a more or less spherical distortion of a planar structure, this structure also being produced in principle in the same way as the structures already described or subjected to torsion. In addition, a recess, a flange and a hole are provided on the edge of the partial spherical shell.

Figure 1 5 illustrates another way of producing a lattice structure from perforated sheets or wire lattice structures. To do this, first use flat, perforated sheets or wire mesh laid on top of each other and connected to each other according to a predetermined scheme. Then the two outer grids are as large as possible and at many points between the connection points are detected and pulled apart, so that in cross section the diamond-shaped distortion shown at the top right in FIG. This lattice structure can be inserted, for example, as a reinforcement structure between flat elements.

In the upper part of FIG. 1 5, left and in the middle are indicated by circles or black dots, where the connection of several layers takes place. Specifically, in the example shown, four layers of the triangular grid visible on the left in a plan view are placed on top of one another. The four layers denoted by a, b, d, and d are preferably connected to one another in each case at superimposed grid node points, for example by spot welding, but two adjacent layers are only connected to one another at every second grid point. In FIG. 1 5, four connection points are indicated by circles in the top view in the top view, the position of which in the different planes in the middle part can be seen at the top in FIG. 1 5. Thus, the two layers b and c are attached to each other only at every second horizontal row of lattice points at the respective lattice points, and the layers a, b and c, d are attached to each other only in the intermediate horizontal rows of lattice points. The layers a to d connected in this way are then detected at the two outer layers a, d and pulled apart in the opposite direction, so that the exploded diamond structure results from the same viewing direction as in the middle part of FIG. The position of the connection points is again indicated by dotted connection lines in the right part at the top in FIG.

In the lower part of FIG. 1 5, three different views of the lattice structure produced in this way are shown, the plan view on the left in the lower part of FIG. 5 showing that the structure in the upper part on the left in FIG shortened accordingly in the vertical direction. The grid structure can be seen in the view from below at the bottom right, while the side view which can also be seen at the top right in FIG.

FIG. 1 6 illustrates a further method for producing the lattice structures according to the invention, which can be produced from alternating layers of flat and folded lattices and can always be thought of as such in principle, but which can also be produced concretely in a different way. For example, in the The first example shown above in FIG. 1 6 is a flat lattice structure, for example the flat lattice shown at the top left in FIG are connected so that the structure shown at the top right in FIG. 16 is obtained. This process can also be extended to two or more layers, as shown in the second and third rows in FIG. For this purpose, a corresponding grid is first folded down in a zigzag and then back again to the first level, whereupon this process is repeated several times, so that the structures shown on the left in the second and third rows of FIG. 1 6 result. By pushing together or connecting the closest corners of the trapezoidal or triangular structures, the grating structures shown schematically in the second and third rows on the right are obtained according to FIG. 1 6. It goes without saying that the starting grating must be adapted to the respective manufacturing process if one wants to produce a lattice structure by different types of folds or by connecting flat and folded lattices, in which at least some of the triangles formed are each connected at their corners, even if it is possible in principle that the connection between different triangles at the Sides or with a corner on the side of an adjacent triangle or rectangle.

FIG. 17 shows a device for producing folds in a flat grid, for example a perforated sheet. A sheet 10 of perforated sheet metal can be seen in FIG. 1 7, the holes made in this sheet sheet having the shape of regularly arranged, equilateral triangles, so that the remaining material, which defines the sides of the triangular holes, is essentially continuous in shape , linear elements on the one hand in the longitudinal direction of the sheet metal strip and on the other hand at an angle of 60 ° in opposite directions. A part of the lines extending obliquely across the web, which are designated by the reference number 16 in FIG. 17, defines the fold lines along which the web 16 is folded. This path is relatively similar to the path according to FIG. 1, but sheet metal strips have also remained along the fold lines d ₁ - d shown in FIG. 1, so that instead of the diamond shape of the individual holes, the already mentioned shape of the equilateral triangles is created. However, the fold lines follow exactly the same course as in FIG. 1 and thus also along the sheet metal strips 16 that have remained at this point.

The sheet metal strip 10 is first inserted into a feed mechanism 1 1, which is designed to advance the sheet metal strip 10 step by step, so that with each stroke a folding tool 14, 1 5 a new fold can be formed so as to produce the folded sheet metal strip 20. For the exact positioning of the individual folds, a pair of holding stamps 12, 1 3 is provided, which have a plurality of interlocking webs and grooves which are precisely adapted to the shape of the folds to be produced.

Both the threading tools 14, 1 5 and the holding tools 1 2, 1 3, as indicated by double arrows, can be moved towards and away from one another in the vertical direction. To produce a new fold, the tools 12, 13 or 14, 15 are moved apart, whereupon the feed mechanism 11 moves the perforated sheet metal strip 10 forward by approximately one fold length. The tools 12, 13 then close and thereby engage in the last fold produced and, if appropriate, also in further folds previously produced. Subsequently, the folding tools 14, 15 are closed or moved towards one another, a new fold being produced. However, the feed mechanism 11 must release the sheet metal strip 10 to a certain extent, since the sheet metal strip 10 is retracted to a certain extent by the formation of a new fold.

This process is continued continuously, the resulting pattern roughly corresponding to the image shown in FIG. 2, with sheet metal material only being additionally present along the folding lines d1, d2 or d3, d4.

Also in the case of the device according to FIG. 17, the resulting folded sheet metal strip 20 is angled laterally in relation to the unfolded bending strip 10, as shown in FIG. 2.

FIG. 18 shows a welding device which is intended to produce the connection from a flat sheet metal sheet 30, as shown in the detail in FIG. 3, to a folded sheet metal sheet 20, for example in accordance with FIG. 2. In this case too, a feed mechanism, shown only schematically and designated by 21, is provided, through which a folded web 20 and a flat web 30 are fed simultaneously and one above the other. At a short distance behind the feed mechanism, holding tools 22, 23 and 26, 27 are provided, which hold the folded sheet metal web 20 and the sheet metal web 30 just passing through tightly together on both sides of the weld seam to be produced during a welding process. The holding tools 22, 23 and 26, 27 have a very similar shape as the holding tools 12, 1 3 of the folding machine. The lower holding tools 23, 27 are, however, flat or flat, since they are provided for engagement with the flat sheet metal web 30. For welding, a lower electrode 25 is provided with a flat surface, which comes into firm contact with the underside of the lower sheet metal web 30. Through the feed mechanism 21, the flat sheet metal web 30 and the folded sheet metal web 20 are each moved step by step by a distance between folds. For precise alignment of the flat sheet metal web 30 and the folded sheet metal web 20, the upper holding tools 22, 26 have on their lower surface, which engages with the folded sheet metal web 20, a structure which corresponds exactly to the folds in the form of alternating, groove-shaped depressions and elongated projections. The surface of the lower holding tools 23, 27 is essentially flat, but may also additionally contain positioning pins or the like, which engage in the holes provided in the lower sheet metal web 30 and thereby for a precise alignment of the lower folding lines which come into contact with the lower sheet metal sheet 30 of the upper sheet metal sheet 20 with the corresponding structures of the lower sheet metal sheet 30.

The upper holding tools 22, 26 are raised to advance the two sheet metal webs 20, 30. The electrode 24 is retracted in the direction of the double arrow. If necessary, the lower holding tools 23, 27 and, if necessary, the electrode 25 can also be moved downward. Then the two metal strips 20, 30 are moved exactly one fold distance, measured in the longitudinal direction of the two strips, and the holding tools 22, 23 and 26, 27 are closed, so that both metal strips 20, 30 are held in a precisely positioned position. The lower electrode 25, if it is not yet in contact with the lower surface of the sheet metal strip 30, is raised and brought into contact with each, preferably the lower electrode 25 bears against the lower sheet metal strip 30 under a prestress. The upper electrode 24 is provided in the form of a copper roller with a wedge-shaped cross-section, the wedge cross-section of the roller being selected so that it can roll in each of the folds of the folded sheet-metal strip 20 and thereby grasp the bottom of the relevant fold with its edge. A feed rod 28 moves the roller 24 longitudinally through the fold, which is thereby also pressed down into the bottom of the fold to achieve sufficient contact pressure which causes the current to flow between the upper electrode 24 and lower electrode 25, through which the intermediate compressed bleaching strips 20, 30 are welded together.

Alternatively, one could use an elongated, wedge-shaped electrode 24 'instead of the roller electrode 24, the length of which covers the entire length of a fold, so that the fold by pressing down the wedge-shaped electrode 24' and thereby triggering a corresponding current flow in a single step on its whole Length with the one below Sheet metal strip 30 is welded.

It goes without saying that the electrodes 24, 24 'do not necessarily have to have a wedge-shaped cross section, but could also be provided, for example, in the form of a flat strip with flat opposite surfaces or could also have individual pins which each engage one of the grid points to make the weld.

Claims

P a t e n t a n s r u c h e

1 . Three-dimensional lattice structure, which consists at least predominantly of triangles, which, preferably at their respective corners, are firmly connected to one another and thus span a spatial structure, characterized in that the structure by casting, injection molding or die casting, by firm connection, such as, for example Welding or gluing flat and / or corrugated or folded two-dimensional lattice is produced by layer-by-layer construction, such as stereolithography, by coating existing three-dimensional lattice structures or any combination of the aforementioned methods.

2. Lattice structure according to claim 1, characterized in that it consists at least partially of metal.

3. Lattice structure according to claim 1, characterized in that it consists at least partially of wax, plastic or ceramic.

4. Lattice structure according to one of claims 1 to 3, characterized in that the triangular sides defining linear elements form at least five, preferably six different groups with each other parallel elements.

5. Grid structure according to one of claims 1 to 4, characterized in that the triangles formed in each case lie in five different groups of spatially differently arranged planes, the planes of a group each running parallel to one another.

6. Lattice structure according to one of claims 1 to 5, characterized in that the triangular elements have partially curved triangular sides.

7. Lattice structure according to one of claims 1 to 6, characterized in that at least some of the triangular elements arranged linearly one behind the other are inclined by a small angle to the preceding and / or subsequent triangular element, so that a series of linearly arranged triangular elements as a whole is curved Bahn describes.

8. Lattice structure according to one of claims 6 or 7, characterized in that the lattice structure is limited by surfaces which are at least partially curved in space.

9. Lattice structure according to claim 8, characterized in that it is produced by large-scale deformation from a grid with flat boundary surfaces, the radii of curvature of the deformation being large compared to the length of the sides of the individual triangles of the structure.

10. Lattice structure according to one of claims 1 to 9, characterized in that it is constructed from a diamond lattice folded uniformly along parallel diagonals, the diamond tips lying in the boundary planes of the folded lattice are connected to the corner points of flat rectangular lattices.

1 1. Lattice structure according to claim 10, characterized in that the flat rectangular grid is divided by diagonal elements into a sub-grid consisting of right-angled triangles.

1 2. Lattice structure according to one of claims 1 to 1 1, characterized in that the individual sides of the triangle are formed from hollow, tubular elements.

1 3. Lattice structure according to claim 1 2, characterized in that the interior spaces of the hollow, tubular elements are connected to one another and are preferably sealed off or sealed off from the outside.

14. Lattice structure according to claim 1 2 or 1 3, characterized in that the hollow tubular elements are filled with a material which is preferably lighter than the material from which the tubular elements are made.

1 5. Lattice structure according to claim 14, characterized in that the material of the tubular elements is chemically and / or physically connected to the filling material.

1 6. Lattice structure according to one of claims 12 to 1 5, characterized in that the tubular elements are made by coating a lattice structure which forms the filling material of the tubular elements.

1 7. Lattice structure according to claim 1 6, characterized in that the lattice structure forming the filling material has a porous surface.

1 8. Lattice structure according to one of claims 1 to 1 7, characterized in that it consists of cast material.

1 9. Lattice structure according to one of claims 1 to 1 8, characterized in that it is at least partially limited by planes inclined at an angle to one another.

20. Lattice structure according to one of claims 1 to 1 9, characterized in that its boundary planes are twisted in themselves or have a torsion.

21. Method for producing a three-dimensional lattice structure which consists at least predominantly of triangles, which are preferably firmly connected to one another at their respective corners and thus span a spatial structure, characterized in that the structure is cast by casting into a hollow mold made of a molding material such as molding sand , will be produced.

22. A method for producing a three-dimensional lattice structure which consists at least predominantly of triangles, which are preferably firmly connected to one another at their respective corners and thus span a spatial structure, characterized in that a model of the lattice structure is produced and the model is subsequently made with lattice structure material or a Molding material is coated.

23. The method according to claim 21 or 22, characterized in that in a first step a model of the lattice is made of a material which is easily meltable and has good flowability in the liquid state in comparison with the final material of the lattice structure.

24. The method according to any one of claims 21 to 23, characterized in that the model is constructed from two identical basic structural elements, which consist of elements lying in one plane, parallel and essentially one-dimensional elements, as well as from other, protruding from the aforementioned plane in a zigzag pattern and the parallel elements at every other corner of the zigzag pattern are made up of essentially one-dimensional elements which are in line with the remaining free ones Zigzag corners face each other and are twisted together in such a way that the free, convex corners each fall in the concave corners of the opposite basic structural element, where the two basic structural elements are then connected to one another.

25. The method according to any one of claims 21 to 24, characterized in that in a form of a mutually folded triangular mesh along parallel triangular sides or a mutually folded diamond mesh along parallel diagonal, a model mass, such as. B. wax, is injected in liquid form, that in a form of a flat rectangular grid or a rectangular grid composed of right triangles with diagonals also a model mass, such as. B. wax, is injected in liquid form, that the folded grid of model mass is aligned such that it is placed between two flat rectangular grids in such a way that the corners of the triangles coincide in the adjacent planes of the folded and flat grids and are then firmly connected to one another, so as to form a lost model of the lattice structure.

26. The method according to claim 25, characterized in that the model is expanded by further folded and flat layers to a five- or multi-layer model.

27. The method according to any one of claims 21 to 24, characterized in that the model is produced by building up in layers, for example by stereolithography using a laser.

28. The method according to claim 27, characterized in that the layers are built up under computer control.

29. The method according to any one of claims 21 to 28, characterized in that the model is coated in a conventional manner with molding sand, dried or hardened and optionally sintered, and that the model mass after drying or hardening by liquefaction or gasification and / or combustion removed from the mold and the resulting hollow shape is poured out with the lattice structure material.

30. The method according to any one of claims 21 to 29, characterized in that the lattice structure is produced by immersing the model in a liquid bath, which contains the material from which the lattice structure is made, or components thereof.

31 Method according to one of claims 21 to 30, characterized in that the model is coated by physical or chemical vapor deposition.

32. The method according to any one of claims 21 to 30, characterized in that the model is coated electrostatically or galvanically and optionally previously given an electrically conductive coating.

33. The method according to any one of claims 21 to 29, characterized in that the model is coated by spraying or painting.

34. The method according to any one of claims 21 to 33, characterized in that the model material is porous at least on its surface.

34. The method according to any one of claims 21 to 33, characterized in that the material of the lattice structure with which the model is coated enters into a chemical and / or physical bond with the model material.

36. The method according to any one of claims 21 to 35, characterized in that the lattice structure material is treated physically and / or chemically.

37. The method according to any one of claims 21 to 36, characterized in that the material of the lattice structure is finally painted or is otherwise provided with a chemical or physical corrosion protection layer.

38. A method for producing a three-dimensional lattice structure which consists at least predominantly of triangles, which are preferably firmly connected to one another at their respective corners and thus span a spatial structure, characterized in that the structure is produced by welding flat and folded lattices, a folded grid is aligned and placed on a flat grid and wherein a welding electrode rests on the outside of the flat grid and an opposite electrode engages in one of the folds of the folded grid.

39. The method according to claim 38, characterized in that a wedge-shaped electrode extending at least over part of the length of a fold is used as the electrode engaging in the fold.

40. The method according to claim 38, characterized in that a roller-shaped electrode with a wedge-shaped roller cross-section is rolled over the bottom of the fold.

41. Method according to one of claims 38 to 40, characterized in that perforated metal sheets are used as flat and folded grids.

42. The method according to claim 41, characterized in that the holes provided in the sheet material are triangular or diamond-shaped.

43. The method according to claim 41 or 42, characterized in that the holes are made by punching or etching.

44. Device for producing a three-dimensional lattice structure according to one of claims 37 to 42, wherein at least one folded lattice is electrically welded to a flat lattice or another folded lattice, to be precise at the corner points or side sections of the folded lattice forming the folded lattice Triangles or diamonds, characterized in that the device is provided with an electrode which is sufficiently narrow in profile, for example a wedge-shaped electrode or a roller-shaped electrode with a wedge-shaped roller profile, for engaging in the bottom of a grid fold and has devices which have the wedge or the Presses roller against the bottom of such a fold, a counter electrode is provided which supports the folded grid and a further grid and is opposite the wedge-shaped electrode or the roll-shaped electrode.

45. Apparatus according to claim 44, characterized in that a counter electrode is provided in a wedge or roll shape with a wedge-shaped profile.

46. Apparatus according to claim 44, characterized in that the counter electrode is a flat or convex, z. B. cylindrical, support surface.

47. Device according to one of claims 44 to 46, characterized in that it has a positioning device which keeps the two grids aligned relative to one another and with respect to the electrodes in such a way that the welding takes place at least partially at the grid nodes.

48. Device according to one of claims 44 to 47, characterized in that several electrodes side by side for the simultaneous or short successive welding in several parallel folds, wherein a feed device is provided for the intermittent feed by a multiple fold distance.

49. Grid structure according to one of claims 1 to 20, characterized in that it consists of layers of perforated sheet material or grids arranged in layers, wherein the layers are connected to one another according to a predetermined pattern of connection points and moved apart between the connection points to a larger layer distance.

50. Lattice structure according to one of claims 1 to 20 or 49, characterized in that connection points of various sub-lattices, from which the lattice structure is constructed, are equipped with interlocking surface sections.