DE102013008026A1 - Process for producing moldable honeycomb cores - Google Patents

Abstract

The invention relates to a method for the production of malleable honeycomb cores, characterized by the following steps 1.1 shaping a flat, curved or web-shaped processing material into a meandering structure with essentially horizontally and vertically extending surfaces, 1.2 introducing a folding pattern into the vertically extending surfaces of the Meander-shaped structure, whereby the horizontal surfaces are enlarged by a part of the previous vertical surfaces and the remaining previous vertical surfaces are reshaped in a zigzag pattern, 1.3 Sharp-edged formation of the folding lines to form the folding sheet or the folding path, 1.4 Various design options for further processing into 3-D Expansion honeycomb.

Description

The invention relates to a method for the production of moldable honeycomb cores according to the preamble of claim 1.

Plate-shaped sandwich composites usually consist of two cover layers, which are shear-resistant connected with a light core layer. Based on this structure, advantageous mechanical properties of the composite result with comparably low weight.

Cores for sandwich composites, in particular cores with a cavity structure (eg honeycomb structure) generally have a significantly lower density than the cover layers.

A variant of a core with a cavity structure are hexagonal honeycomb cores. For the first time, such a structure was in the patent DRP 133165 described. Today, hexagonal honeycomb cores are produced as unexpanded paper honeycomb cores for the field of furniture and interior design as well as for related areas and are only expanded immediately prior to the production of the sandwich panels, which entails the advantage of a very low transport volume. Among other things, sandwich panels with such cores enable high specific compressive strengths across the board plane, an enormous weight saving and a reduced consumption of raw materials.

Conventional hexagonal honeycomb cores consist of a honeycomb-like, hexagonal structure, which is formed by the gluing of paper strips k of defined thickness s and subsequent expansion, expansion. The direction of production X is the direction in which it is expanded. A three-dimensional view of a clipping is going in 2 and a single cut out cell as a top view 3 shown.

The regions of the bond are referred to as double webs a1 and the non-bonded regions as simple webs a2. With most production plants a variety of core heights h can be produced.

Due to their structure, conventional expanded honeycomb cores are severely limited in their formability. In the case of two-dimensional forming i. d. R. the problem of so-called saddle formation. A production of any two- and three-dimensionally shaped sandwich components with expandable honeycomb core has previously been possible only by the destruction of the core structure in the areas of heavy forming. With very thin components, the uncontrollable buckling or tearing of webs of the honeycomb structure is sometimes deliberately accepted.

There are already different three-dimensionally formable honeycomb cores. Such a honeycomb core is for example from the EP 0 955109 A2 known. Such structures are complex in their production and also do not offer the possibility of transport to the final processor in the unexpanded state. Thus, such three-dimensionally deformable cores are expensive and are used only for a few applications. They exist z. B. of aramid fiber paper, which is impregnated after its formation with resin, or aluminum.

In the publication DE 10 2009 005 869 A1 describes an expandable honeycomb core that is shapeable in the transverse and longitudinal directions without damage to the structure and thus allows a three-dimensional shaping of sandwich components without affecting the honeycomb core (3-d expansion honeycomb). A three-dimensional view of a clipping is going in 4 and a single cut out cell as a top view 5 shown. Similar to the conventional expandable honeycomb cores, the 3-d expansion honeycomb consists of individual web layers / folded paper strips of thickness s, which are connected to one another by alternately following double webs b1 and simple webs b2, so that upon expansion a honeycomb-like structure is formed. The connection is made by the strip sections are glued together in the region of the double webs. According to the invention, the simple webs b2 of the 3-d expansion honeycomb additionally have predetermined bending lines which divide the simple webs into three regions b2.1, b2.2, b2.3. This structure allows the defined folding of the honeycomb core formed in the transverse and / or longitudinal direction and at the same time increases the compressive strength of the sandwich composite. In addition to the three-dimensional shaping, it is also possible to produce one-dimensional and two-dimensional sandwich composites. In addition to paper as starting material for the 3-d expansion honeycomb other raw materials such as aramid fiber paper with subsequent impregnation of resin or aluminum can be used. The 3-d expansion honeycomb can be manufactured in any desired core heights h.

Components with conventional honeycomb cores have significantly reduced strength values due to the buckling or tearing of webs in the case of two- or three-dimensional deformation. Therefore, such honeycomb cores are rarely used for two-dimensionally or three-dimensionally shaped components. A variant of the application is the use of petroleum-based foams (for example polyurethane foams) as the core layer of three-dimensional sandwich elements, which, for. T. is also combined with the use of conventional honeycomb cores. The production of a However, such sandwich composite is relatively expensive and disadvantageous for later recycling.

Sandwich composites of the type discussed here can be implemented as a one-dimensional plate as well as a two-dimensional or three-dimensionally shaped component. Specifically two- and three-dimensionally shaped components are increasingly used in industries such as aircraft, automotive, caravan construction, shipbuilding and boatbuilding, but also in furniture and exhibition construction and in immobile interior design. The cover layers usually consist of correspondingly deformable materials such as plastic, metal, wood and wood-based material or (natural) fibers.

Already existing in shape three-dimensional honeycomb cores are already available, but these are very expensive, so that they are used only in a few applications. In addition, due to the already existing expanded form, comparably high storage and transport costs follow. Low-cost three-dimensionally shaped sandwich components with expandable honeycomb core can not be produced because of the lack of an industrially producible deformable core layer.

That in the patent ( DE 10 2009 005 869 A1 ) presented method for producing the 3-d expansion honeycomb provides, the predetermined bending lines in the areas of the free webs by folding, embossing o. The like. To introduce. In the practical implementation shows that a purposeful buckling machine-made honeycomb cores in the protected manner is technically extremely complicated to implement.

Object of the invention

The object of the present invention is to provide an industrially applicable method for producing the 3-d expansion honeycomb with improved technology.

In the method sheet or sheet-shaped flat product, consisting mostly of paper, alternatively, from other starting materials such as aramid fiber paper with subsequent resin impregnation or aluminum processed. In addition, even connecting elements or means for joining the individual web layers / folded paper strips, such. B. adhesive used.

The complex transformation required for the production of the 3-d expansion honeycomb is achieved in several successive substeps. The possibly present fiber orientation of the material to be processed as well as the deflections and fold lines introduced during processing lie parallel to the machine direction of rotation (MLR).

• 1.1 Umformen eines flachen, bogen- bzw. bahnförmigen Verarbeitungsgutes, dem Rohbogen bzw. der Rohbahn, zu einem mäanderförmigen Gebilde mit im Wesentlichen horizontalen und vertikalen Flächen,
• 1.2 Einbringen eines Faltmusters in die vertikalen Flächen des mäanderförmigen Gebildes durch Längsfalzen, wobei die horizontalen Flächen um einen Teil der zuvor vertikalen Flächen vergrößert werden und die restlichen vorherigen vertikalen Flächen im Zickzack-Muster umgeformt werden,
• 1.3 Komprimieren des eingebrachten Musters zum Falzbogen, bzw. zur Falzbahn,
• 1.4 Weiterverarbeiten des Falzbogens, bzw. der Falzbahn zur 3-d-Expansionswabe

The process according to the invention for producing the 3-d expansion honeycomb is carried out by the following steps:

• 1.1 forming a flat, sheet-like or sheet-like material to be processed, the raw sheet or the raw sheet, to a meander-shaped structure with substantially horizontal and vertical surfaces,
• 1.2 inserting a folding pattern into the vertical surfaces of the meandering structure by longitudinal folding, wherein the horizontal surfaces are increased by a part of the previously vertical surfaces and the remaining previous vertical surfaces are formed in a zigzag pattern,
• 1.3 compressing the introduced pattern to the folded sheet, or to the folding path,
• 1.4 Further processing of the signature, or the folding path to the 3-D expansion honeycomb

In an advantageous variant of the method, the folded sheet or the fold path is alternately cut from above and below at a distance of the later core height h to the whereabouts of only one paper thickness transverse to the machine direction and the coherent blocks thus formed by folding around the remaining processing material and the 3rd -d expansion honeycomb pressed. The application of adhesive can take place before or after the cutting.

In a further advantageous variant of the method, webs / folded paper strips are separated from the folding sheet or the folding web transversely to the machine direction and lined up by pressing them about the longitudinal axis in the correct position to form double webs of the 3-d expansion honeycomb and compressed. The application of adhesive can take place before or after the separation. The distance between the two cuts gives the core height h.

In a further advantageous variant of the method, a plurality of folded sheets or folding webs are adhesively bonded to one another in the correct position to form double webs. The processing takes place further in that at the same time several, already bonded web layers / folded paper strips are separated transversely to the machine direction and these aligned in the same direction to form double webs of the 3-d expansion honeycomb and pressed to the 3-d expansion honeycomb. The second application of adhesive may take place before or after the separation of the already glued folded sheets or folding paths. The distance between the two cuts gives the core height h.

In a further advantageous variant of the method, a plurality of signatures or folds are glued together in the correct position assignment to form double webs. From the resulting block, the 3-d expansion honeycomb in any core height h is separated.

Advantageously, the meander-shaped structure is formed with substantially horizontal and vertical surfaces in a pronounced Zinnenfriesform or with larger radii at the transitions, to a complete curvature of the horizontal sections.

Further advantageous is the introduction of a folding pattern in the vertical surfaces of the meander-shaped structure in zig-zag shape by the action of corresponding web guiding elements, designed as a mold rail arrangement, achieved during the advance of the sheet or the web.

Advantageously, the mold rails are designed in such a way that all required deflections of the folded sheet or the fold web are introduced into the processed good by multiple, parallel longitudinal folding. The mold rails can be correspondingly shaped individual parts or assemblies with correspondingly shaped individual elements. A form of rail is characterized in that it introduces the required deflections in the processed material during conveyance through the mold rail assembly. For this vertical elevations of the mold rail from the meander shape along the rail to the folded sheet or Falzbahn must enlarge and reduce the height of the rail, so that the transformation can take place without unwanted mechanical impairment of the processed material. Vertical indentations of the mold rail, which increase along the mold rail, provide the space needed for the forming.

Further advantageously, for the conveyance of the material to be processed and for the deformation of the deflections to form sharp folding lines Zugwalzenpaare find application.

Further advantageously, individual mold rails can be moved relative to the rest to reduce the required conveying forces. Likewise, by supplying compressed air, a flow around the mold rails with air and thus a reduction of the conveying forces can be achieved. But it can also find other lubricants application.

The invention will be explained in more detail below with reference to exemplary embodiments. In the accompanying schematic representations show:

1 a possible procedure,

2 a three-dimensional view of a section of a conventional hexagonal honeycomb core,

3 a plan view of a cell of a conventional hexagonal honeycomb core,

4 a three-dimensional view of a section of the 3-d expansion honeycomb,

5 a top view of a cell of the 3-d expansion honeycomb,

6 a three-dimensional view of a section on the result of the first forming process, a meandering shape,

7 a three-dimensional view of a section of the second forming process, which converts the meandering shape into a folded sheet or a fold sheet,

8th a three-dimensional view of a section of the result of the second forming process, which represents the initial state for several possibilities of further processing to the 3-d expansion honeycomb,

9 a three-dimensional view of a section of the result of a slightly modified first forming process, with modified meandering shape,

10 a side view of a possible further processing in which the folded sheet or the Falzbahn be alternately cut from above and below and then converted to 3-d expansion honeycomb,

11 a three-dimensional view of a possible further processing in which the folded sheet or the fold sheet is divided into sections, which are in turn subjected to adhesive and arranged appropriately form the 3-d expansion honeycomb,

12 a three-dimensional view of a possible further processing in which the folded sheet or the fold sheet, is repeatedly joined together by means of adhesive, is separated into sections and these are finally joined together with adhesive to the 3-d expansion honeycomb,

13 a three-dimensional view of a possible further processing in which the folded sheet or the fold sheet, are often joined together by means of adhesive to a block from which the 3D Expansion honeycomb is separated in the desired core height.

The respective conveying directions of the method are marked with arrows.

A basic procedure of the method according to the invention is in the 1 shown.

In the first step, a flat, bow-shaped or web-shaped processing material is conveyed into or through a die. The resulting shape consists of alternating vertically and horizontally contiguous surfaces. Transverse to the machine direction Y thus creates a meandering, in the example 6 a pinnacle frieze shape. However, the result of this first parting process can also be a cross section that is slightly different from the Zinnenfries form. So can the deflections between vertical 5 and horizontal surfaces 4 also be run with a larger radius. In extreme cases, up to the complete curvature of the horizontal surfaces, 9 ,

By this first step, the required for further processing web or sheet width reduction and thus a targeted concentration of the processed material is achieved. In the process flow 1 becomes the result of this first transformation left of the cut 1.1 shown.

In the following step, between cut 1.1 and 1.2 the existing meandering shape is reshaped by longitudinal folds to the folded sheet or to the folding path. For this forming step special tools, mold rails are necessary, which bring in all the required fold lines during conveying of the processing material by a multiple, parallel Längsfalzen. During forming, the horizontal surfaces become 4 . 7 to a part of the previously vertical surfaces 5a extended. The remaining area is in a zigzag pattern 5b , c, d reshaped. A section of the processed material during the transformation provides 7 It is not absolutely necessary that the bending lines be introduced with sharp-edged tools. For example, the tools may also be designed such that the edges required for the forming process have a radius that decreases along the tool 5r are executed.

After forming, the resulting folding pattern is compressed by means of suitable aids, such as a roller pair, whereby the fold lines are finally formed on the deflections, 8th , In the process,

1 This shape exists between cut 1.2 and 1.3 , The introduced fold lines act in the later honeycomb core like hinges between the surfaces. The enlarged horizontal surfaces 4 + 5a . 8th form the double webs b1 in the expanded state of the 3-d expansion honeycomb, 4 and the zigzag folded surfaces 5b , c, d, 8th the simple webs b2.1, b2.2, b2.3, 4 , As a result, in cross-section to the MLR, a kind of constantly changing ornament emerges from one long and three shorter lines. The lines are connected via deflections, transferred to the room these are the fold lines. Vertically, the pattern can be mirrored by half of the long lines, as exemplified in 8th with the mirror image plane 5s and the sections a and a 'is illustrated.

For the further processing of the folding sheet or the folding path to the 3-D expansion honeycomb there are several possible embodiments. One is in 1 exemplified with. A side view of this process is in 10 shown. It is the folded material to be processed in the area of the later double webs first adhesive on one side. This is done between cut 1.2 and 1.3 , Next, the folding pattern is cut to the last layer of the processed material and hinged around 180 °. The previously applied adhesive layer on the double webs causes the material connection of the individual hitherto only hinge-like sections to the 3-d expansion honeycomb.

Another way to make the 3-expansion honeycomb from the fold sheet or the fold path is to separate strips from the folding pattern, to apply these before or after separation with adhesive and to handle the individual folding pattern strips so that they glued and accordingly compressed form the 3-d expansion honeycomb, 11 , In this case, the folding pattern can be previously glued together already in several versions 12 ,

It is also possible to glue together a multiplicity of folded sheets or folding trays, to compress them and finally to separate the 3-d expansion honeycombs from the resulting block in the desired core height, 13 ,

Finally, the unexpanded honeycomb core can be expanded in two directions to the 3-d expansion honeycomb. In order to reduce storage and transport costs, the expansion can be temporally and spatially offset, similar to the expansion of conventional hexagonal honeycomb cores, carried out only at the user.

Another way to inexpensively transport and store the 3-d expansion honeycomb is to fully expand the 3-d expansion honeycomb during the manufacturing process and in only one dimension to repress the machine direction. In this form, the 3D expansion honeycomb is transported and stored in a space-saving and cost-effective manner. The advantage of this design is that expanders for conventional honeycomb cores can also be used to expand the 3D expansion honeycomb and so the user does not need to provide new machine technology.

Depending on the design, the presented method for producing the 3d expansion honeycomb can work continuously or discontinuously. Depending on the method of operation, sheets or webs can be processed.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 133165 [0004]
• EP 0955109 A2 [0008]
• DE 102009005869 A1 [0009, 0013]

Claims (7)

Process for the production of moldable honeycomb cores, characterized by the following steps: 1.1 forming a flat, curved or web-shaped material to be processed to a meander-shaped structure with substantially horizontal and vertical surfaces, 1.2 inserting a folding pattern into the vertical surfaces of the meandering structure by longitudinal folding, wherein the horizontal surfaces are enlarged by a part of the previously vertical surfaces and the remaining previous vertical surfaces are formed in a zigzag pattern, 1.3 Sharp-edged forming of the fold lines to the folded sheet or to the fold sheet, 1.4 Further processing to the 3-d expansion honeycomb. A method according to claim 1, characterized in that the folded sheet or the fold web is alternately cut from above and below at a distance of the later core height to the whereabouts of only one paper thickness transverse to the machine direction, the formed contiguous blocks by folding around the remaining processing material and to 3-d expansion honeycomb are pressed, wherein the cohesion is prepared by an applied before or after the separation of adhesive. A method according to claim 1, characterized in that webs / folded paper strips are separated from the folding sheet or the fold path transversely to the machine direction and aligned by appropriate rotation about the longitudinal axis in the correct position to form double webs of the 3-d expansion honeycomb and pressed, wherein the Apply with adhesive before, or after separation can take place. Method according to claim 1, characterized in that web layers / folded paper strips are separated from a plurality of glued-together folded sheets or folding webs transversely to the machine direction, applied thereto before or after the release with adhesive and then joined in the correct position to form double webs for the 3-d expansion honeycomb become. A method according to claim 1, characterized in that a plurality of folded sheets or Falzbahnen is glued in positionally correct association with the formation of double webs and the 3-d expansion honeycomb is separated from the resulting block. Method according to one of claims 1 to 5, characterized in that the meander-shaped structure is formed with substantially horizontal and vertical surfaces in a pronounced Zinnenfriesform or with a curvature in the horizontal portion. Method according to one of claims 1 to 6, characterized in that the introduction of the folding pattern in the surfaces of the meander-shaped structure is effected by the action of corresponding web guiding elements during the advancement of the sheet or the web.

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