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

Abstract

The invention relates to a method (100) for producing a metal foam product (1) having a metal foam made of an aluminium-containing material, comprising the method steps (102, 104, 106, 108): providing a tool mould (1000) which has at least one portion (1008) made of a cast aluminium material, wherein the portion delimits at least part of the mould interior (1006) of the tool mould; coating at least some portions of an inner surface (1010), facing the mould interior, of the portion with a release agent (1012); 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, such that the material is foamed. The invention also relates to a tool mould. The method according to the invention and the tool mould according to the invention lead to energy-efficient and uniform heating of the aluminium material in the tool mould. 

Description

Method for producing a metal foam product from an aluminium-containing material with the aid of a tool mould sectionally coated with a release agent, and tool mouldThe invention relates to a method for producing a metal foam product from an aluminium-containing material with the aid of a tool mould coated in some portions with a release agent and to a tool mould. Metal foam products made of aluminium are becoming increasingly widespread, as they are resilient and energy-absorbing while requiring little material, and exhibit high heat conductivity. However, the production of such metal foam products is not straightforward. For example, the aluminium-containing material is foamed by supplying heat with the aid of a heat-activated release agent such as Ti2O. This requires a considerable amount of heat input, distributed as evenly as possible across the surface. The heat supplied to the tool mould should be transferred to the aluminium material and the blowing agent as efficiently as possible and with minimal loss.The underlying object of the invention is therefore to provide a method and a tool mould which ensure energy-efficient and uniform heating of the aluminium material within the tool mould.According to the invention, this problem is solved by a method for producing a metal foam product using a metal foam made of an aluminium-containing material, comprising the method steps:- providing a tool mould which has at least one section made of a cast aluminium material, wherein the section delimits at least a part of the mould interior of the tool mould;- at least sectionally coating an inner surface of the section with a release agent, the inner surface facing the mould interior;- 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, such that the material is foamed.This problem is further solved by a tool mould for producing a metal foam product from an aluminium-containing material, wherein the tool mould comprises at least one section made of a cast aluminium material, the section having an inner surface which delimits a mould interior and is coated with a release agent.The advantage of these two solutions is that the section made of cast aluminium material with the top and / or bottom of the tool mould exhibits high heat conductivity, so that heat input directed at the top and / or bottom is distributed evenly across the surface and conducted into the mould interior with only minimal losses. Until now, steel has been used for the top and / or bottom. However, the metal foam can bond to the top and / or bottom. In order to prevent this, a release agent is used. This results in the further advantage that the bond between the top and / or the bottom can be controlled by the use of the release agent. Thus, if a metal foam product is desired that has a composite structure at least in sections, that is, where sections have a top and / or bottom layer consisting, for example, of a plate or another shape, part of the top and / or bottom may not be coated with a release agent, so that at this point the metal foam and the top and / or bottom form a metallic bond.The invention can be further improved by the following advanced features, each of which is preferred in its own right and can be combined with any other as desired. The features described below can be used indiscriminately both to improve the method and to improve the tool mould.Thus, in one configuration, the release agent may comprise or consist of boron nitride, graphite and / or a ceramic, in particular aluminium oxide or a carbide such as tungsten carbide. These release agents are heat-resistant and reliably prevent the metal foam from bonding to the top and / or bottom.The tool mould is preferably reusable, or is reused. This reduces production costs. The pot and / or the top may be assembled from individual segments, so that tool moulds with different geometric shapes can be put together. The individual segments may be, or will be, coated with a release agent independently of one another. For example, at least one segment may remain uncoated, so that it bonds with the metal foam and becomes part of a composite structure. This segment is, of course, not reusable, but forms part of the metal foam product.The segments may be made of different materials. For example, materials with different heat conductivities may be used. In this way, the heat input into the mould interior can be influenced by the arrangement of the segments. This makes it possible to compensate for uneven heat input, which is predetermined by the furnace, or to specifically influence the structure of the metal foam in individual areas. According to a further configuration, even those segments that become part of the metal foam product because they bond with the metal foam may be made of a different material compared to the segments that remain within the tool mould.The bottom may be pot-shaped and, for example, have a raised rim to which the top abuts. Of course, the top may also be pot-shaped and have a raised rim that abuts the bottom. Finally, both the top and the bottom may each have a rim that abuts the other element – that is, the bottom or the top. The rim does not have to be continuous. The rim may be formed by individual segments, while other segments have no rim.The invention is explained below by way of example with reference to the Figures. In accordance with the above explanations, individual features described below may be omitted in the relevant embodiment if the technical effect of these features is not essential for a particular application. Conversely, a feature described above but not described below may be added to the relevant embodiment if the technical effect of this feature is essential for a particular application.It is shown by:Fig. 1 a schematic view of a metal foam product;Fig. 2 a schematic view of a method for producing a metal foam product;Fig. 3 a schematic view of a tool mould for producing a metal foam product; andFig. 4a schematic view of a further tool mould for producing a metal foam product.Fig. 1 shows a metal foam product 1 comprising a metal foam 2. The metal foam product 1 may be provided with a cover layer 4 on one or more sides, thereby forming a composite workpiece. The metal foam product 1 may have virtually any three-dimensional shape.The cover layer 4 does not have to be applied to a flat side 6 of the metal foam product 1, as shown. Alternatively, or cumulatively, a cover layer 4 may also be arranged on a narrow side 8. As shown, the cover layer 4 may cover only part of one side of the metal foam 2. It may also cover an entire side.There is preferably a metallic bond between the cover layer 4 and the metal foam 2.For the production of the metal foam product 1, the method 100 shown schematically in Fig. 2 is carried out. In a first step 102 of the method 100, a tool mould 1000 is provided. In this con-text, a mould interior 1002 of the tool mould 1000 has the same geometric three-dimensional shape as the metal foam 2 in the metal foam product 1. It should be noted that the metal foam product 1 can be machined using either cutting or non-cutting processes, if this is necessary for individual applications. For example, the metal foam product 1 can be reshaped in order to bring it into a different shape for an application. Additionally or cumulatively, the metal foam product 1 can be provided with bores and milled-out portions, punched holes and / or additional parts.In particular, the tool mould comprises a top 1004 and / or a bottom 1002 made from a cast aluminium material. The bottom 1002 and / or the top 1004 may be assembled from individual segments 1014, as explained in more detail below with reference to Fig. 4. The segments 1014 can, for example, be used to form different three-dimensional shapes.In a second step 104, the top 1004 and / or the bottom 1002 are coated at least in some portions, with a release agent 1012. The release agent 1012 is, for example, a ceramic such as aluminium oxide, in particular Al2O3, or a carbide such as tungsten carbide. Graphite or boron nitride may also be used as the release agent 1012. Where the top 1004 and / or the bottom 1002 is coated with the release agent, the metal foam 2 does not bond to the top 1004 and / or the bottom 1002. Thus, if, for example, a segment 1014 is not coated with the release agent 1012, it can form a cover layer 4 of the metal foam product 1.In step 106, the tool mould 1000 is filled with the aluminium-containing material and a blowing agent. The aluminium-containing material may be in the form of strips. The blowing agent may be added in the form of strip- or strand-shaped compacts. Filling is made easier if the bottom 1002 is pot-shaped and, for example, has a raised rim 1003, which does not, however, need to be continuous.The mould is then sealed by placing the top 1004 onto the bottom 1002.In step 108, the tool mould 1000 is heated so that the blowing agent is activated and the aluminium-containing material is melted, thereby producing the metal foam 2. Infrared rays are preferably used to heat the tool mould 1000.The tool mould 1000 is then cooled, either actively or passively, and the metal foam product 1 – which is now ready for any further processing – is removed.The tool mould 1000 can then be reused, provided that no individual segments 1014 have remained as the cover layer 4 on the metal foam product 1.Fig. 3 shows the tool mould 1000 with a bottom 1002 and a separate top 1004, which surround a mould interior 1006 of the tool mould 1000. The mould 1000 comprises at least one section 1008 made of a cast aluminium material, wherein the section 1008 delimits at least part of the mould interior 1006. An inner surface 1010 of the bottom 1002 and / or the top 1004 may be provided, at least in sections, with a release agent 1012. The bottom 1002 is shown here, by way of example, as having a rim 1003. The bottom 1002 and / or the top 1004 may be made of different materials.According to Fig. 4, the bottom 1002 and / or the top 1004 may be constructed from individual segments 1014. The segments 1014 may form part of a modular system 1016 comprising more segments 1014 than those currently used in the mould 1000. Some segments 1014 may be configured with a rim 1003, while other segments 1014 may be configured without a rim 1003. Different three-dimensional shapes can be composed from different segments 1014.The segments 1014 may be made of different materials. However, at least one segment 1014 is made of a cast aluminium material. Furthermore, at least one segment 1014 is coated with a release agent. For example, a segment 1014 that is intended to remain as cover layer 4 in the metal foam product 1 may be made of steel, while a segment 1014 coated with release agent 1012 may be made of the cast aluminium material.Reference signs1 metal foam product2 metal foam4 cover layer6 flat side8 narrow side100 method102 first step104 second step106 third step108 fourth step1000 tool mould1002 bottom1003 rim1004 top1006 mould interior1008 section1010 inner surface1012 release agent1014 segments

Claims

1. A method (100) for producing a metal foam product (1) using a metal foam (2) made of an aluminium-containing material, comprising the method steps (102, 104, 106, 108):providing a tool mould (1000) which has at least one section (1008) made of a cast aluminium material, wherein the section (1008) delimits at least a part of the mould interior (1006) of the tool mould (1000);at least sectionally coating an inner surface (1010) of the section (1008) with a release agent (1012), the inner surface (1010) facing the mould interior (1006);filling the mould interior (1006) of the tool mould (1000) with the aluminium-containing material and a blowing agent;heating the tool mould (1000) with the material and blowing agent contained therein, so that the material is foamed.

2. Method (100) according to claim 1, wherein the release agent (1012) comprises or consists ofboron nitride;graphite;a ceramic, in particular 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 section (1008) of the tool mould (1000) comprising the cast aluminium material.

4. Method (100) according to claim 1 to 3, comprising the following method step:assembling the tool mould (1000) from individual segments (1014).

5. Tool mould (1000) for producing a metal foam product (1) from an aluminium-containing material, wherein the tool mould (1000) comprises at least one section (1008) made of a cast aluminium material, the section (1008) having an inner surface (1010) which delimits a mould interior (1006) and is coated with a release agent (1012).

6. Tool mould (1000) according to claim 5, wherein the release agent (1012) comprises or consists ofboron nitride;graphite;a ceramic, in particular aluminium oxide or a carbide such as tungsten carbide.

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

8. Tool mould (1000) according to one of claims 5 to 7, wherein the section (1008) is configured to be assembled from several segments (1014).

9. Tool mould (1000) according to one of claims 5 to 8, wherein the section (1008) forms at least a part of a bottom (1002) and / or a top (1004) of the tool mould (1000).

10. Tool mould (1000) as per claim 9, wherein the segments (1014) are made of different materials.

11. Tool mould (1000) according to claim 9 or 10, wherein the bottom (1002) is pot-shaped.

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