method for producing metallic reticular structures
Abstract
Process for the manufacture of metallic reticular structures by using a reticular structure, preferably a lattice structure of foam, in which the casting channels formed by such structures are stabilized by organic materials before the metal is introduced. The procedure is characterized by the following steps: (a) Thermal compression, flat or separately, of the previous structure, so that it presents pores of increasing size inward and, thereby, a graduated structure in the area of compression . (b) Thickening of the nerves of the reticular structure by a coating, applied once or several times, of an organic material or of several materials, preferably two organic materials in this case. (c) Introduction of the coated structure in a container in continuous and open joint at the top, as well as the filling of the structure with a fireproof mass. (d) Performing perforations, grooves or similar, through and / or non-through, in the previous structure filled in, with a minimum distance of at least two pores from each other. (e) Removal of the solidified structure and ceramic assembly from the container and introduction of the assembly into a cuvette whose bottom is filled with loose fireproof material. (F) Removing the previous structure by thermal rearrangement in an oven. (g) Inserting the cuvette into a pressure resistant container. (h) Placing a sandbox for molds or ceramics on the bucket and the upper surface of the ceramic body, so that the edges of the ceramic body are free as a casting channel and the pot constitutes an insulation of the bucket, with in order to avoid premature solidification of the metal to be introduced. (i) Metal introduction / closure of the pressure-resistant container. (j) Evacuation of the pressure-resistant container, in order to wear away the metal and the spacer. (k) Aeration of the container, extraction of the cuvette and cooling.

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Projected expiry passed 31 May 2025, 1.3 years ago.
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11 claims: 5 independent, 6 dependent
- 1ES 2 285 604 T3 REIVINDICACIONES 1. Procedimiento para la fabricación de estructuras reticulares metálicas mediante la utilización de una estructura reticular, preferentemente una estructura reticular de espuma, en la que los canales de colada formados por tales estructuras se estabilizan mediante materiales orgánicos antes de introducir el metal. El procedimiento se caracteriza por los siguientes pasos:(a) Compresión térmica, plana o por separado, de la estructura previa, de forma que ésta presente poros de tamaño creciente hacia adentro y, con ello, una estructura graduada en el área de la compresión. (b) Engrosamiento de los nervios de la estructura reticular mediante un revestimiento, aplicado una o varias veces, de un material orgánico o de varios materiales, preferentemente dos materiales orgánicos en este caso. (c) Introducción de la estructura revestida en un recipiente en unión continua y abierto en la parte superior, así como el rellenado de la estructura con una masa incombustible. (d) Realización de perforaciones, acanaladuras o similares, pasantes y/o no pasantes, en la estructura previa rellenada, con una distancia mínima entre sí de al menos dos poros. (e) Retirada del conjunto solidificado de estructura y cerámica del recipiente e introducción del conjunto en una cubeta cuyo fondo está relleno de material incombustible suelto. (f) Retirada de la estructura previa mediante transposición térmica en un horno. (g) Introducción de la cubeta en un recipiente resistente a la presión. (h) Colocación de una terraja de arena para moldes o de cerámica sobre la cubeta y la superficie superior del cuerpo cerámico, de forma que los bordes del cuerpo cerámico queden libres como canal de colada y la terraja constituya un aislamiento de la cubeta, con el fin de evitar una solidificación prematura del metal a introducir. (i) Introducción del metal/cierre del recipiente resistente a la presión. (j) Evacuación del recipiente resistente a la presión, con el fin de desgasear el metal y el espaciador. (k) Aireado del recipiente, extracción de la cubeta y puesta a enfriar.
- 2Procedimiento para la fabricación de estructuras reticulares metálicas según la reivindicación 1 a , con la característica de que el material orgánico utilizado para el revestimiento de los nervios es cera líquida.
- 3Procedimiento según la reivindicación 1a, con la característica de que el material orgánico utilizado para el revestimiento de los nervios es un polvo de cera.
- 4Procedimiento según la reivindicación 1a, con la característica de que el material orgánico utilizado para el revestimiento de los nervios es polvo de poliestireno.
- 5Procedimiento según la reivindicación 1a, con la característica de que el material orgánico utilizado para el revestimiento de los nervios es polvo de poliamida.
- 6Procedimiento según las reivindicaciones 1a, 4a y 5a, con la característica de que el poliestireno/la poliamida implican una pequeña proporción de adhesivo, preferentemente del 5%.
- 7Procedimiento según las reivindicaciones 1a a 6a, con la característica de que, en caso de la aplicación de varios revestimientos sobre los nervios de la estructura reticulada, los diferentes revestimientos se aplican a diferentes temperaturas, entre los 40 y los 80°C.
- 8Procedimiento según las reivindicaciones 1a a 7a, con la característica de que el revestimiento múltiple de los nervios se lleva a cabo con dos modificaciones de cera, las cuales tienen diferentes temperaturas de fusión.
- 9Procedimiento según las reivindicaciones P a 7a, con la característica de que el revestimiento múltiple de los nervios se lleva a cabo con una capa de cera y una de polvo.
- 10Procedimiento según la reivindicación 1a, con la característica de que el material suelto incombustible correspondiente al paso procedimental (c) es arena de fundición.
- 11Procedimiento según la reivindicación 1a, con la característica de que se utilizan como estructura previa rellenos de materiales granulados minerales o materiales granulados orgánicos con revestimiento mineral.
Independent claims11
37 paragraphs in 3 sections, as filed
ES 2 285 604 T3
DESCRIPTION
Procedure for the manufacture of metal lattice structures.
The invention corresponds to a process for the manufacture of metal lattice structures in the form of open-pore foam.
Thanks to their properties, lattice structures made of metal and other materials have a multitude of applications. For example, these structures can be used as lightweight construction elements, accumulator plates, electrochemical anodes and cathodes, filters and mixers for fluids, catalysts, gas absorbers and heat carriers, in addition to many other applications.
Processes for the manufacture of metal lattice structures have been known for some time. However, these procedures are not usually sufficient for an industrial application, due to the difficult handling of the materials used, the complexity of the steps to follow and the time they consume.
For example, US Patent 3,616,841 shows a process for the manufacture of a foam material with a predetermined network structure.
This process comprises: the manufacture of a self-supporting cross-linked polyurethane foam; the manufacture of a noncombustible mass by filling the voids in the polyurethane foam with a suspension of aqueous molded semi-finished product, which sets; heating the non-combustible molded mass to a temperature of about 120 ° C (250 ° F) for two hours for drying; the creation of voids in the non-combustible molded mass by heating it to between 650 and 850 ° C, which causes all of the foam to volatilize; the addition of a molten substance, composed of metals or metallic alloys, to fill the gaps previously made in the crosslinked structure; the solidification of the molten substance by reducing the temperature to a level below the melting point of the substance; and the removal by washing of the material that makes up the non-combustible molded mass.
However, this procedure does not seem particularly suitable for an industrial application, especially for the automated manufacture of metal lattice structures, for the following reasons: The foamy structure determines the technical parameters of the final product, so that the statistical dispersion should be the most reduced possible, to guarantee the technical parameters of the final product. Furthermore, to fill the branched voids in the non-combustible molding with a molten metal it is necessary to heat the molding to temperatures above the melting point of the substance used. This makes the solidification of the metal very slow. Consequently, a solidified metal with a coarse granulation structure is obtained, which in turn reduces the solidity of the structure. To solve this problem, US patent 3,616,841 proposes different cooling methods, such as spraying with water or air. However, the cooling effect is considerably reduced, since the molded mass interferes with the heat flow. Also the manufacture of solid metal areas together with the lattice structure presents the problem of slow cooling. The aforementioned steps make a controlled solidification of the metal very difficult or impossible to obtain a structure without lumps and fine grain. In addition, the slowness of the solidification of the metal implies long-term processes, which also makes automated production difficult.
DE 199 39 155 shows a process for the manufacture of metal lattice structures in which a reticulated foam pre-structure is introduced into a container with a hinged lid, the pre-foam structure is infiltrated with a non-combustible material and the non-combustible material is solidified. . Next, the solidified non-combustible material is removed from the container, the previous foam structure is removed from the non-combustible material, and the resulting previously heated body is placed in a heat-resistant container. This body is infiltrated with a bath of molten metal and, once this solidifies, the body is removed from the heat-resistant container. The non-combustible material is then removed from the body, resulting in a metal lattice structure.
This process has the advantage, among others, that, contrary to what happens with US patent 3,616,841, it is not necessary to adhere the metal pre-structure with the casting system and the casting funnel. This not only considerably reduces the time and material consumption for the manufacture of the mold, but also makes possible an automated manufacture of metal lattice structures.
Although the process shown in DE 199 39 155 considerably simplifies the manufacture of metal lattice structures, it is clear that the consumption of time and material continues to be relatively high, so that, although automated manufacturing is possible, the mass production of this type of structure still involves a high cost, compared to mass production of comparable products. Especially the large quantity of molded semi-finished product that dries and is fired, without being able to be reused in the process, represents a cost that is impossible to compensate. The insulating effect of the molded semi-finished product requires long-term processes. In this way, a production under market conditions is not possible.
Consequently, the object of the invention is to eliminate the drawbacks of current solutions. It is especially a question of presenting a process for the manufacture of metallic lattice structures that requires reduced amounts of material and that allows a faster production and, therefore, in series, of this type of structures.
The characteristics of claim 1 correspond to this objective.<sup>to</sup>. Claims 2<sup>to</sup> to 11<sup>to</sup> define useful settings.
The invention provides, on the one hand, for thermal compression, flat or separately, of the previous structure, so that it has pores of increasing size inwards and, therefore, a graduated structure in the compression area. On the other hand, for the manufacture of metallic lattice structures it is envisaged to use a pre-lattice structure, preferably a PU foam structure, in the way that is known in principle, but whose ribs have previously been thickened by one or more coatings.
ES 2 285 604 T3 with one or more different organic materials. Surprisingly, it has been found that the aforementioned, together with the other procedural steps of the invention, facilitates the influx of the material. At the same time, it is thus possible to precisely modify the mechanical properties of the structure. In this sense, the sustainable improvement achieved in terms of the reproducibility of the characteristic values with respect to current technology is essential.
By modifications in the formula and / or in the process, the thickness of the ribs of the PU foam structure is adapted to the corresponding requirements, determined by the application for which the metallic mesh structure is intended. The invention provides for coating the ribs of the preframe by means of fluid and / or solid materials, for example by dipping the preframe in liquid wax and then coating it with wax powder (having a different melting temperature) or with a powder. polymer, such as polystyrene or polyamide powder, which may also contain a small proportion of adhesive, preferably 5% vol. In particular, the use of powders prevents the structure from adhering and ensures a layer of homogeneous thickness, since, in addition, no membranes are formed between the ribs.
Once the previous structure is thus created, it is fixed in a molded semi-finished product for the casting process.
In this process, the pre-frame is fitted into the frame and filled with the molded semi-finished product so that it is not completely covered, but rather a margin of between 2 and 5 mm is left free. The remaining voids are filled with sand and compressed. The coating of the previous structure is carried out by means of a ceramic slip, and is repeated if necessary to obtain a stable layer. If necessary, the embedded part can be pre-machined, for example by milling and drilling, to create buttons or other geometric shapes of solid material in the structure, or by perforations that allow the introduction of male dowels in order to obtain tubular conduits. in the structure. According to the invention, the perforations, grooves and the like, whether through or not, must be made in the cast pre-structure leaving a distance of at least two pores between them. Thanks to this procedural step, it is possible to increase the density of the material and, consequently, its stability, depending on the desired application. At the same time, a lasting improvement in thermal conductivity is obtained. The diameters of the cavities are optimized according to the requirements regarding the strength of the material.
Another essential procedural step consists of thermally removing the previous structure, by melting or by firing. To do this, the set of structure and ceramic is removed from the frame and placed in a bucket whose bottom is filled with a loose non-combustible material, preferably foundry sand. As an alternative, it is also possible to dry and cook the molded part without a tray, by means of infrared or microwave.
The bowl comprises a sand die for the molds or a ceramic die for the runners. In addition, it is insulated to prevent premature cooling of the molded part. The bucket preferably consists of compressed mold sand and a ceramic compound. The sand for molds is recyclable and, in addition, the use of molded semi-finished product is reduced to the necessary volume.
After these procedural steps, casting and molding are carried out. For this, the bowl with the molded part is placed in a pressure-resistant container, filled with liquid metal, the container closed and evacuated, in order to degas the molded part and the melt. The container is aerated to draw the melt into the molding. The crucible is in the container; the bowl is connected to the melt by a tube.
After casting and solidifying the outer metal layer, the molded part is removed from the pan. Solidification can be directed through cast-bonded metal parts.
In principle, the pre-structure can also be produced by pouring mineral granules or organic granules with a mineral coating. These granular structures, preferably ball-shaped pellets, make it possible to considerably increase the size of the pores of the reticular structure. While PU foam structures usually allow obtaining pores of a maximum of 5 ppi, equivalent to an average pore diameter of between 8 and 10 mm, the aforementioned procedure allows sizes of between 1 and 3 cm to be achieved. For this, it is necessary to adhere the pellets to each other on large surfaces, to ensure that only the gaps between the pellets are used as a pouring channel. It is not intended to coat the previous structure thus created, nor is it necessary, since the desired ceramic coating is already present. The other procedural steps of the invention are maintained. The structure thus manufactured constitutes a lightweight material with multiple possible applications.
The invention is presented in greater detail below by way of exemplary embodiments. The figures show the following:
Fig. 1: schematic representation of a part of the previously described reticular structure, made as a PU foam structure 1 (preliminary structure) with ribs 2.
Fig. 2: PU foam structure with coating 3, preferably composed of two layers, one of liquid wax and one of polymer.
Fig. 3: PU foam structure 1 covered with the molded semi-finished product 4 (ceramic slip), and which, thus, can be processed in the manner described.
Fig. 4: plan of the possible shape (circular, oval) of the pellets 7, composed of mineral granulated materials or organic granulated materials with a mineral coating, and joined by pouring or adhesion. The previous structure thus created differs from the PU 1 foam structure by the considerably larger pore size.
Fig. 5: Molded semi-finished product / molded part 5 and the pores 6, created by thermal removal of the ribs.
Fig. 6: molding 5, inserted into the tray
8.
Fig. 7: cuvette 8, in turn inserted into pressure-resistant container 9.
List of reference signs
PU foam structure (pre-structure)
ES 2 285 604 T3
<td> 2</td><td>Nerve</td><td></td><td> 6</td><td>Pore</td>
<td> 3</td><td>Coating</td><td></td><td> 7</td><td>Pellet</td>
<td> 4</td><td>Molded semi-finished product</td><td rowspan="2"> 5</td><td> 8</td><td>Bucket</td>
<td> 5</td><td>Fired molded semi-finished product / fired molded part</td><td> 9</td><td>Container.</td>
Contents3
2 sheets
Sheet 1 Sheet 2
Every citation, both ways
| Document | Relation | Office | Cited during |
|---|---|---|---|
| US9789534B2 | Cited by | United States of America | Applicant |
| US9884363B2 | Cited by | United States of America | Applicant |
| US9789536B2 | Cited by | United States of America | Applicant |
| US10259036B2 | Cited by | United States of America | Applicant |
| US10252326B2 | Cited by | United States of America | Applicant |
| EP3112048A1 | Cited by | European Patent Office (EPO) | Search report |
9 members in 5 offices
Priority claims5
| Document | Office | Kind | Date |
|---|---|---|---|
| 102004026959 | Germany | A | |
| 102004026959 | Germany | A | |
| 20041026959 | Germany | – | |
| 10200402695905011668 | – | – | – |
| DE20041026959 | – | – | – |
Members9
| Document | Office | Kind | |
|---|---|---|---|
| EP1604756A2 | European Patent Office (EPO) | A2 | |
| EP1604756A3 | European Patent Office (EPO) | A3 | |
| DE102004026959B3 | Germany | B3 | |
| EP1604756B1 | European Patent Office (EPO) | B1 | |
| AT357302T | Austria | T | |
| ATE357302T1 | Austria | T1 | |
| DE502005000489D1 | Germany | D1 | |
| PL1604756T3 | Poland | T3 | |
| ES2285604T3This record | Spain | T3 |
Numbers
- Publication
- 2285604
- Publication, DOCDB
- 2285604
- Publication, EPODOC
- ES2285604T
- Application
- 5011668
- Application, DOCDB
- 05011668
- Application, EPODOC
- ES20050011668T
Titles2
- Spanish
- PROCEDIMIENTO PARA LA FABRICACION DE ESTRUCTURAS RETICULARES METALICAS.
- English
- PROCEDURE FOR THE MANUFACTURE OF METALLIC RETICULAR STRUCTURES.
Classification
- CPC, 5
- B22D25/005
- B22C7/02
- B22C7/023
- B22C9/02
- B22C9/043
- IPC, 2
- B22D19 14
- B22C9 04