Method for producing a metal foam product from an aluminium-containing material with the aid of a tool mould having a mould core coated with a release agent, and tool mould

Abstract

The invention relates to a method (100) for producing a metal foam product (1) having a cavity (4) of predetermined shape with a metal foam (2) made of an aluminium-containing material, comprising the following method steps (102, 104, 106, 108, 110): providing a tool mould (1000) with a mould core (1004) having the predetermined shape; coating at least some portions of an outer surface (1006) of the mould core facing the part (1008) of the mould interior (1002) that is accessible to the metal foam with a release agent (1010); filling the mould interior of the tool mould with the aluminium-containing material and a blowing agent; heating the tool mould with the material and blowing agent located therein, so that the material is foamed; removing the mould core from the metal foam product. By means of the method according to the invention and the tool mould according to the invention, metal foam products having complex geometries can be produced cost-effectively and with little effort.

Description

[0001] Method for producing a metal foam product from an aluminum-containing material using a mold having a mold core coated with a release agent, and mold

[0002] The invention relates to a method for producing a metal foam product from an aluminum-containing material using a mold having a mold core coated at least in sections with a release agent, as well as to a mold and a metal foam product.

[0003] Metal foam products made from aluminum are becoming increasingly popular because they are resilient, energy-absorbing, and exhibit high thermal conductivity while requiring minimal material. Such metal foam products are manufactured by foaming the aluminum-containing material with the aid of a heat-activated release agent such as Ti2O. Complex geometries are difficult to produce.

[0004] The invention is therefore based on the object of being able to manufacture metal foam products with complex geometries cost-effectively and with little effort.

[0005] This object is achieved according to the invention by a method for producing a metal foam product having a cavity of a predetermined shape with a metal foam made of an aluminum-containing material, comprising the method steps:

[0006] - Providing a tool mold with a mold core having the predetermined shape;

[0007] - at least partially coating an outer surface of the mold core facing the part of the mold interior accessible to the metal foam with a release agent;

[0008] - Filling the interior of the tool mold with the aluminum-containing material and a blowing agent;

[0009] - Heating the tool mould with the material and blowing agent inside it so that the material is foamed;

[0010] - Removing the mold core from the metal foam product.

[0011] This object is further achieved by a mold for producing a metal foam product from an aluminum-containing material having a cavity of a predetermined shape, wherein the mold has a mold core having the predetermined shape, wherein an outer surface of the mold core facing the part of the mold interior accessible to the metal foam is coated at least in sections with a release agent. The advantage of these two solutions is that metal foam products having cavities can be produced in a simple and cost-effective manner. Such cavities reduce the density and thus the production costs of the metal foam product. Furthermore, the metal foam product according to the invention has a high degree of functional integration and a broad spectrum of possible applications.For example, the cavities of the metal foam product can be used to accommodate electrical cables or cooling lines.

[0012] Using the above solutions, it is also possible to create channels directly in the metal foam. In particular, the walls of the channels are formed by the metal foam itself, which saves material. Furthermore, this design enables direct heat exchange between the channels and the metal foam forming the channels, without any intermediate components. This increases energy efficiency.

[0013] The invention can be further improved by the following features, each of which is advantageous in itself and can be combined with one another as desired. The features described below can be used indiscriminately both to improve the process and to improve the tool shape.

[0014] In one embodiment, the release agent can comprise or consist of boron nitride, graphite, and / or a ceramic, in particular an aluminum oxide or a carbide such as tungsten carbide. These release agents are heat-resistant and reliably prevent bonding between the metal foam and the mold core.

[0015] The mold is preferably reusable or is reused. This reduces manufacturing costs.

[0016] To simplify the assembly and disassembly of the mold, according to one embodiment, the mold can have at least one receptacle accessible from outside the mold for the mold core, in which the mold core can be accommodated at least partially. The mold core can be inserted into the mold through the receptacle and / or removed from it. A mold core accommodated in the receptacle of the mold can be accessible from outside the mold.

[0017] To improve accessibility to the mold core, at least a portion of the mold core can be arranged outside a part of the tool mold that encloses the mold interior. The mold core can thus extend from the mold interior to the outside of the mold interior, for example, through a wall, in particular a lid or base of the tool mold. To make the production process more energy-efficient, the energy required to heat the tool mold and / or to foam the material can, in one embodiment, be introduced at least partially, and according to another embodiment, even completely, via the mold core.

[0018] To further reduce energy losses, the energy required to heat the tool mold, in particular thermal energy, can, according to one embodiment, be introduced exclusively via that section of the mold core which is arranged outside the part of the tool mold enclosing the mold interior.

[0019] To reduce the mass of the mold core and thus production costs, as well as to improve the handling of the tool mold, the mold core can be hollow. The mold core can have an opening, in particular a through-opening, which can extend along a longitudinal axis of the mold core through the entire mold core. In one embodiment, the mold core is tubular, preferably designed as a metal tube. The cavity within the mold core can be accessible from outside the tool mold.

[0020] According to one embodiment, the mold core can be cylindrical, at least in sections. Such a mold core is easy to manufacture and can be manufactured with high precision. Of course, the mold core can also be completely cylindrical. Furthermore, the mold core can be prismatic, conical, and / or hollow-cylindrical, at least in sections. In particular, a conical shape of the mold core can simplify the insertion and / or removal of the mold core into or from the mold cavity.

[0021] In a further embodiment, the mold core can comprise or consist of a cast aluminum material. The high thermal conductivity of cast aluminum materials ensures that the thermal energy introduced via the mold core is evenly distributed across the outer surface of the mold core and conducted to the mold interior with minimal loss. Of course, the mold core can also comprise or consist of other metallic materials, alternatively or cumulatively.

[0022] In order not to impair the stability of the manufactured metal foam product, the mold core can extend to different side surfaces of the mold interior. The points at which the mold core borders the inner surface of the tool mold facing the mold interior can thus be located on different side surfaces of the mold interior. The different side surfaces can be opposite, in particular parallel, side surfaces of the mold interior of the tool mold. The mold core can be one-piece or multi-piece and thus composed, for example, of individual segments, so that cavities with different geometric shapes can be produced in the metal foam product. The individual segments can be or will be coated with release agents independently of one another.For example, at least one segment can remain uncoated, bonding with the metal foam and becoming part of a composite structure. This segment is, of course, not reusable but is part of the metal foam product.

[0023] The segments can be made of different materials. For example, materials with different thermal conductivities can be used. In this way, the heat input into the mold cavity can be influenced by the composition of the segments. This can compensate for uneven heat input, which is determined by the furnace, or specifically influence the structure of the metal foam in individual areas. According to a further embodiment, the segments that become part of the metal foam product because they bond with the metal foam can be made of a different material than the segments that remain in the mold.

[0024] The mold can be designed to produce a metal foam product with multiple intersecting or penetrating cavities. The cavities can be defined, in particular, by different segments of the mold core, each of which can have different cross-sections or spatial shapes. The mold core can have multiple struts or branches, for example, extending at right angles or acute angles to one another, which define the cavities in the metal foam product to be produced. Of course, the mold core can also be designed to produce multiple non-intersecting or non-penetrating cavities, for example, cavities arranged parallel to one another.

[0025] The shape and position of the mold core can influence the direction along which heat energy is transferred between the mold core and the material or blowing agent during heating and / or cooling of the mold. If the metal foam product manufactured with this mold contains cooling or heating devices during its subsequent use, particularly cooling lines running through the cavities, the direction of heat transfer or heat dissipation between the cooling lines and the metal foam product can be influenced by the shape and position of the cavities.

[0026] The problem is further solved by a metal foam product made of a metal foam made of an aluminum-containing material, with a hollow space, wherein the average cell size decreases toward a boundary surface of the hollow space immediately surrounding the hollow space. Such a metal foam product is both resilient and lightweight.

[0027] The material density of the metal foam product can thus increase toward an interface of the cavity immediately surrounding the cavity. In particular, a density distribution can increase parabolically toward the interface. The metal foam product or metal foam can have a closed foam surface at the interface and, in particular, be completely smooth.

[0028] The metal foam can be an integral skin foam, or the metal foam product can consist of an integral skin foam. The term "integral skin foam" can refer to a metal foam whose cell structure becomes denser toward an interface and has an outer skin at the interface, which is preferably closed and / or smooth.

[0029] The invention is explained below by way of example with reference to the figures. Subject to the above explanations, individual features described below may also be omitted from the corresponding embodiment if the technical effect of these features is not important for a particular application. Conversely, a feature described above but not described below may also be added to the corresponding embodiment if the technical effect of this feature is important for a particular application.

[0030] They show:

[0031] Fig. 1 is a schematic representation of a metal foam product;

[0032] Fig. 2 is a schematic sectional view of another metal foam product;

[0033] Fig. 3 is a schematic representation of a process for producing a metal foam product;

[0034] Fig. 4 is a schematic representation of a tool mold for producing a metal foam product; and

[0035] Fig. 5 is a schematic perspective view of another metal foam product.

[0036] Fig. 1 shows a metal foam product 1 comprising a metal foam 2. The metal foam product 1 has at least one cavity 4 which extends at least partially through the metal foam product 1. Both the metal foam product 1 and the cavity 4 can have almost any spatial shape. In the illustrated embodiment, the metal foam product 1 has a cuboid shape through which an essentially cylindrical cavity 4 passes. The cavity 4 can extend from a first side surface 6 of the metal foam product 1 to a second side surface 8 of the metal foam product 1, arranged parallel to the first side surface 6. Of course, the cavity 4 can also extend between side surfaces 10 that are not opposite one another.

[0037] At one or more locations, particularly in the region of the cavity 4, the metal foam product 1 can have a cover layer 12, thus creating a composite material. A metallic bond preferably exists between a cover layer 12 and the metal foam 2. In the illustrated embodiment, the cover layer 12 extends along an interface 14 directly surrounding the cavity 4; however, the cover layer 12 can also cover the entire interface 14.

[0038] As shown in Fig. 5, the metal foam product 1 can also have multiple cavities 4. In the illustrated embodiment, the cavities 4 have different spatial shapes resulting from various cross-sections, namely rectangular, circular, and polygonal. Of course, other cross-sections or spatial shapes are also conceivable. The cross-sections of the cavities 4 do not have to be constant along the longitudinal extent of the cavities 4, as shown in Fig. 5, but can also vary, thereby defining, for example, a conical cavity 4.

[0039] The cavities 4 shown in Fig. 5 intersect, so that the cavities 4 partially penetrate each other or are connected to each other. In the illustrated embodiment, two cavities 4 intersect at right angles, but the cavities 4 can also be arranged at an obtuse or acute angle to each other. According to other embodiments, the cavities 4 can also not intersect or penetrate each other at all and, in particular, can be arranged parallel to each other.

[0040] Fig. 2 shows a schematic sectional view of another metal foam product 1 with a cavity 4. The metal foam product 1 has a plurality of adjacent cells 16, the average size 18 of which varies along the metal foam product 1. In the illustrated embodiment, the average cell size 18 decreases towards the interface 14 immediately surrounding the cavity 4, so that the density of the metal foam product 1 increases towards the cavity 4. The density distribution of the metal foam product 1 can increase, for example, parabolically towards the cavity 4 or the interface 14. At the interface 14, the metal foam product 1 can have a closed, preferably smooth foam surface 20, which can form a solid wall or outer skin surrounding the cavity 4.

[0041] To produce the metal foam product 1, the method 100 schematically illustrated in Fig. 3 is carried out. In a first step 102 of the method 100, a tool mold 1000 is provided. A mold interior 1002 of the tool mold 1000 has the geometric three-dimensional shape that the metal foam 2 has in the metal foam product 1. It should be noted that the metal foam product 1 can be machined or non-machined if necessary for individual applications. For example, the metal foam product 1 can be reshaped to give it a different shape for an application. Alternatively or additionally, the metal foam product 1 can be provided with bores and milled recesses, punchings, and / or additional parts.

[0042] The tool mold 1000 has a mold core 1004 arranged at least partially within the mold interior 1002, which has a predetermined shape of the cavity 4 of the metal foam product 1 to be produced. The nature of the mold core 1004 is explained in more detail below with reference to Fig. 4.

[0043] In a second step 104, an outer surface 1006 of the mold core 1004, which faces a part 1008 of the mold interior 1002 accessible to the metal foam 2, is coated at least in sections with a release agent 1010. The release agent 1010 is, for example, a ceramic, such as aluminum oxide, in particular Al2O3, or a carbide, such as tungsten carbide. Graphite or boron nitride can also be used as release agent 1010. Where the mold core 1004 is coated with release agent 1010, the metal foam 2 does not bond to the mold core 1004. Thus, if, for example, a segment 1012 of the mold core 1004 is not coated with the release agent 1010, it can form a cover layer 12 of the metal foam product 1.

[0044] In step 106, the tool mold 1000 is filled with the aluminum-containing material and a blowing agent. The aluminum-containing material can be in the form of material strips. The blowing agent can be added in the form of strip- or strand-shaped pressed parts.

[0045] Subsequently, the mold 1000 is closed and heated in step 108 so that the blowing agent is activated and the aluminum-containing material is melted, thereby forming the metal foam 2. Infrared rays are preferably used to heat the mold 1000. The energy required to heat the mold 1000 or to foam the material can, in one embodiment, be introduced at least partially via the mold core 1004. The mold 1000 is then actively or passively cooled, and subsequently, in a further step 110, the mold core 1004 is removed from the metal foam product 1. To simplify this process, the mold core can, in one embodiment, have a slight conicity.

[0046] The finished metal foam product 1 can then be removed for possible further processing.

[0047] The mold core 1004 can then be reused, unless individual segments 1012 remain as the cover layer 12 of the metal foam product 1. However, at least those segments 1012 of the mold core 1004 that have not become the cover layer 12 of the metal foam product 1 can be reused.

[0048] Fig. 4 shows the tool mold 1000 with a base 1014 and a separate cover 1016, which between them surround a mold interior 1002 of the tool mold 1000. The tool mold 1000 has the mold core 1004, which in the illustrated embodiment extends between the base 1014 and the cover 1016, i.e., through the mold interior 1002 to two different side surfaces 10 of the mold interior 1002. The mold core 1004 does not have to be accommodated, as shown in Fig. 4, in a receptacle 1018 of the tool mold 1000 that is accessible from outside the tool mold 1000, and thus in particular does not have to extend through the base 1014 and / or cover 1016 of the tool mold 1000.

[0049] The mold core 1004 can have a section 1020 that is arranged outside the part 1022 of the mold 1000 that surrounds the mold interior 1002. For example, as shown in Fig. 4, the mold core 1004 can protrude outward through the cover 1016 of the mold 1000. In one embodiment, the energy required for heating can be introduced, preferably completely, via this section 1020 of the mold core 1004.

[0050] The mold core 1004 has the predetermined shape of the cavity 4 of the metal foam product 1, which can be produced using the mold 1000. The mold core 1004 shown in Fig. 4 is configured as a hollow cylinder. Of course, the mold core 1004 can also have other shapes, such as a cylindrical, conical, or prismatic shape, at least in sections. Furthermore, the mold core 1004 can of course also be configured to be solid, at least in sections, and thus not hollow, at least in sections.

[0051] According to Fig. 4, the mold core 1004 can be constructed from individual segments 1012. The segments 1012 can be part of a modular system that has more segments 1012 than those currently used in the tool mold 1000. Different shapes can be assembled from different segments 1012. The segments 1012 can be made of different materials. For example, one segment 1012 can be made of a cast aluminum material. However, at least one segment 1012 is coated at least in sections with a release agent 1010, which is or will be applied to an outer surface 1006 of the mold core 1004 or a segment 1012 of the mold core 1004 facing the part 1008 of the mold interior 1002 accessible to the metal foam 2.For example, a segment 1012 that is to remain as cover layer 12 of the metal foam product 1 can be made of steel, while a segment 1012 coated with release agent 1010 can be made of cast aluminum material.

[0052] Reference symbol

[0053] 1 metal foam product

[0054] 2 metal foam

[0055] 4 cavity

[0056] 6 first side surface

[0057] 8 second side surface

[0058] 10 side surface

[0059] 12 top layer

[0060] 14 Interface

[0061] 16 cells

[0062] 18 cell size

[0063] 20 foam surface

[0064] 100 procedures

[0065] 102 first step

[0066] 104 second step

[0067] 106 third step

[0068] 108 fourth step

[0069] 110 fifth step

[0070] 1000 tool mold

[0071] 1002 mold interior

[0072] 1004 mold core

[0073] 1006 exterior area

[0074] 1008 accessible part of the mold interior

[0075] 1010 Release agent

[0076] 1012 segments

[0077] 1014 floor

[0078] 1016 lid

[0079] 1018 recording

[0080] 1020 external section

[0081] 1022 part of the tool mold enclosing the mold interior

Claims

Claims 1. A method (100) for producing a metal foam product (1) having a cavity (4) of a predetermined shape with a metal foam (2) made of an aluminum-containing material, comprising the method steps (102, 104, 106, 108, 110): - Providing a tool mold (1) with a mold core (1004) having the predetermined shape; - at least partially coating an outer surface (1006) of the mold core (1004) facing the part (1008) of the mold interior (1002) accessible to the metal foam (2) with a release agent (1010); - filling the mold interior (1002) of the tool mold (1000) with the aluminum-containing material and a blowing agent; - heating the tool mold (1000) with the material and blowing agent contained therein so that the material is foamed; - Removing the mold core (1004) from the metal foam product (1).

2. Method (100) according to claim 1, wherein the separating agent (1010) - boron nitride; - graphite; - comprises or consists of a ceramic, in particular an aluminium oxide or a carbide such as tungsten carbide.

3. Method (100) according to claim 1 or 2, comprising the following method step: - Reusing the mold core (1004) of the tool mold (1000).

4. Method (100) according to one of claims 1 to 3, wherein the energy required for heating the tool mold (1000) and / or for foaming the material is introduced at least partially via the mold core (1004).

5. Tool mold (1000) for producing a metal foam product (1) having a cavity (4) of a predetermined shape from an aluminum-containing material, wherein the Tool mold (1000) has a mold core (1004) having the predetermined shape, wherein an outer surface (1006) of the mold core (1004) facing the part (1008) of the mold interior (1002) accessible to the metal foam (2) is coated at least in sections with a release agent (1010).

6. Tool mold (1000) according to claim 5, wherein the release agent (1010) - boron nitride; - graphite; - comprises or consists of a ceramic, in particular an aluminium oxide or a carbide such as tungsten carbide.

7. Tool mold (1000) according to claim 5 or 6, wherein the tool mold (1000) is reusable.

8. Tool mold (1000) according to one of claims 5 to 7, wherein the mold core (1004) is hollow.

9. Tool mold (1000) according to one of claims 5 to 8, wherein the mold core (1004) extends to different side surfaces (10) of the mold interior (1002).

10. Tool mold (1000) according to one of claims 5 to 9, wherein the tool mold (1000) has at least one receptacle (1018) accessible from outside the tool mold (1000) for the mold core (1004), in which the mold core (1004) can be received at least in sections.

11. Tool mold (1000) according to one of claims 5 to 10, wherein at least a portion (1020) of the mold core (1004) is arranged outside a part (1022) of the tool mold (1000) enclosing the mold interior (1002).

12. Tool mold (1000) according to claim 11, wherein the energy required for heating the tool mold (1000) is introduced exclusively via the section arranged outside the part (1022) of the tool mold (1000) enclosing the mold interior (1002).

13. Tool mold (1000) according to one of claims 5 to 12, wherein the mold core (1004) is cylindrical at least in sections.

14. Tool mold (1000) according to one of claims 5 to 13, wherein the mold core (1004) comprises or consists of a cast aluminum material.

15. Metal foam product (1) made of a metal foam (2) made of an aluminum-containing material, with a cavity (4), wherein an average cell size (18) decreases towards a boundary surface (14) immediately surrounding the cavity (4).

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