DE102022106524A1 - Method for producing a foam element, component and tool - Google Patents

Abstract

Method for producing a foam element, in particular a metal foam element, comprising the steps: - producing a foam element in a cavity of a mold, the mold being in a first closed position, in which the cavity is enlarged compared to a final dimension of the foam element; - method of Molding tool into a second closed position to reduce the size of the cavity, so that its final dimension is adjusted by at least partially compressing an edge region of the foam element.

Description

The present invention relates to a method for producing a foam element, in particular a metal foam element, a component and a tool.

Foam elements, in particular, for example, metal foam elements or metal foam bodies, are fundamentally known from the prior art. Such structures are used, for example, when weight needs to be saved. In the automotive sector, use in crash-relevant areas is also advantageous. Casting around such foam elements, for example for partially stiffening or stiffening cast components, can be very advantageous, but is not unproblematic since the liquid molten metal can penetrate into the porous structure of the foam element and destroy it. The DE 101 23 899 A1 In this context, proposes a method for producing metal moldings, in which a metal body with a closed surface on all sides and a hollow structure inside is inserted into a mold and the remaining mold cavity is then filled with a metal or a metal alloy. The aforementioned metal body should be designed as a metal integral foam. To create the “closed surface”, a blowing agent is added to a molten metal after it leaves a storage container and before entering the mold cavity, see also DE 103 25 819 B4 . Depending on the application, the edge layers that can be created in this way (cf. the aforementioned closed surfaces) may not be sufficiently thick. In addition, it is not possible to control where they are trained.

It is therefore an object of the present invention to provide a method for producing a foam element, a component and a tool, whereby an alternative to the known methods is to be provided, which is characterized by its flexibility and good feasibility

This object is achieved by a method according to claim 1, by a component according to claim 8 and by a tool according to claim 11. Further advantages and features result from the subclaims as well as the description and the attached figures.

• - Erzeugen eines Schaumelements in einer Kavität eines Formwerkzeugs, wobei das Formwerkzeug in einer ersten Schließstellung steht, in welcher die Kavität gegenüber einem Endmaß des Schaumelements vergrößert ist;
• - Verfahren des Formwerkzeugs in eine zweite Schließstellung zum Verkleinern der Kavität, sodass über ein zumindest bereichsweises Komprimieren eines Randbereichs oder einer Randzone bzw. einer äußeren Schicht oder Lage des Schaumelements dessen Endmaß eingestellt wird.

According to the invention, a method for producing a foam element, in particular a metal foam element or a metal foam core, comprises the steps:

• - Producing a foam element in a cavity of a mold, the mold being in a first closed position, in which the cavity is enlarged compared to a final dimension of the foam element;
• - Moving the mold into a second closed position to reduce the size of the cavity, so that its final dimension is adjusted by at least partially compressing an edge region or an edge zone or an outer layer or layer of the foam element.

By moving the mold from the first firing position to the second closed position, the foam element that has already been produced is at least partially compressed or compressed on the circumference or at the edge, as a result of which the foam structure is dissolved or lost in the outer region of the foam element or in the edge region of the foam element. In other words, the process from the first closed position to the second closed position and the forces that are exerted on the foam element cause the foam structure in the edge area to be converted into a more or less closed, solid structure.

A compact/closed or solid edge layer is expediently formed via compression. The original porosity of the foam element is largely destroyed or dissolved by compression or squeezing. An existing edge layer, which may have already formed in the first closed position, advantageously becomes thicker. As a result, a foam element produced as proposed can be used very well as a cast component for use in metal casting, in particular, for example, in permanent mold or die casting. The terms “compact”, “closed” or “solid” are to be understood in particular to mean that such an edge layer is designed to protect the inner “porous” core, in particular to act as a barrier. Such a barrier, for example, prevents the penetration of liquid (metal) melt when pouring around such a foam element.

Depending on the design of the mold, the foam element is compressed or squeezed completely or not. If certain areas of the foam element are not compressed, this can be taken into account when arranging or further using the foam element. According to one embodiment, the molding tool has one or more slides, which can also be used to effect compression of the edge region.

• - Einlegen eines Schaum-Rohlings in das Formwerkzeug;
• - Verfahren des Formwerkzeugs in die erste Schließstellung;
• - Aufschäumen des Schaum-Rohlings zum Erzeugen des Schaumelements;
• - Verfahren des Formwerkzeugs in die zweite Schließstellung.

According to one embodiment, the method comprises the steps:

• - Inserting a foam blank into the mold;
• - Moving the mold into the first closed position;
• - Foaming the foam blank to produce the foam element;
• - Moving the mold into the second closed position.

According to one embodiment, such a blank is produced by mixing metal powder, for example aluminum powder, with blowing agent powder and pressing it under high pressure. The blank can be made to foam by heating. According to one embodiment, the heating is advantageously carried out indirectly via an appropriately designed mold.

• - Verfahren des Formwerkzeugs in die erste Schließstellung;
• - Einbringen einer flüssigen und/oder gasförmigen Materialmischung in die Kavität zum Erzeugen des Schaumelements;
• - Verfahren des Formwerkzeugs in die zweite Schließstellung.

Alternatively, the procedure includes the steps:

• - Moving the mold into the first closed position;
• - Introducing a liquid and/or gaseous material mixture into the cavity to produce the foam element;
• - Moving the mold into the second closed position.

In this embodiment, a liquid melt, such as a metal melt, for example an aluminum melt, which is designed to form a foam element, is introduced/injected into the mold. The foam element created in this way is then compressed by reducing the size of the cavity.

• - Verkleinern der Kavität, nachdem die Kavität vollständig gefüllt ist.

The process expediently basically includes the step:

• - Shrinking the cavity after the cavity is completely filled.

In other words, the process from the first closed position to the second closed position is only initiated when the cavity in the first closed position is completely filled.

In the first closed position, the foam element is expediently solidified at least in some areas in such a way that compression of the edge region can take place at all. This can take different amounts of time depending on the manufacturing process of the foam element and the materials used.

Preferred materials for the foam element are plastic or composite materials, but in particular metallic materials, preferably light metals such as aluminum.

• - Verwenden des Formwerkzeugs zum Konditionieren, insbesondere Erhitzen, des Schaumelements.

According to one embodiment, the method comprises the step:

• - Using the mold to condition, especially heat, the foam element.

This can be advantageous to influence the compression of the edge area. This means that, for example, the formation of the compact/closed surface layer can be influenced by increasing the temperature. For this purpose, the mold is designed accordingly with a conditioning device, such as a heating device. As already mentioned, the foaming process can also be carried out using an appropriately designed mold.

According to one embodiment, the method from the first closed position to the second closed position takes place in pulses or shocks. In this way, a collapse of the edge region can be created or achieved, which results in a particularly compact/solid edge layer. Alternatively, it can also be advantageous to move as slowly as possible from the first to the second closed position in order to compress the edge area as gently as possible. The best solution must be determined on a case-by-case basis.

It has been found that the volume of the cavity in the first closed position is expediently about 10-20% larger than the volume of the cavity in the second closed position. The higher the volume differences in the two closed positions, the higher or more strongly the edge region of the foam element is compressed. In conjunction with an appropriately designed mold, the method offers the advantage that the foam element can only be compressed in certain areas. Accordingly, foam elements can be produced which only have an edge layer in certain areas. Edge layers with different wall thicknesses can also be created. The properties of the foam element can advantageously be adjusted flexibly and individually in relation to the edge layer.

The invention also relates to a component comprising at least one foam element according to the invention.

According to one embodiment, an edge layer of the foam element has a density which is at least twice as large as the density of the core region of the foam element. According to a preferred embodiment, the density of the edge layer is at least twice, three times, four times or five times as great. According to one embodiment, the density corresponds to the edge layer in approximately the density of the base material from which the component is made.

According to one embodiment, a wall thickness of the edge layer expediently does not fall below 1 mm. The edge layer expediently has a thickness of 1.5 mm, 2 mm, 2.5 mm, 3 mm, 4 mm, 5 mm or more millimeters.

The thickness can be adjusted individually by closing the mold or the force acting on the foam element. It is also expedient to create an edge layer which does not have the same wall thickness everywhere, but is adapted to suit requirements. This is a decisive advantage over processes that create such surface layers by adding blowing agents. In the present case, not only the thickness or wall thickness of the edge layer can be adjusted individually, the areas where the edge layer is formed can also be selected. The foam element does not have to completely form such an edge layer.

According to a preferred embodiment, the aforementioned component is a cast component, such as a cast metal component, in which the at least one foam element is at least partially cast as an insert element.

The invention also relates to a tool or molding tool, in particular a plunge edge tool, in particular for carrying out the method according to the invention, comprising a plurality of molded parts which are designed to move to different closed positions, the tool being designed to form a cavity in a first closed position for forming a foam element with oversize, and wherein the tool is designed to move to at least a second closed position in which the volume of the cavity is reduced. The tool is characterized in that the cavity or cavities formed in the closed positions are each closed, so that a foam element is formed or a foam element formed can be compressed or compressed at least in areas.

Further advantages and features result from the following description of an embodiment of the method or a component or a (forming) tool with reference to the attached figures.

• 1: verschiedene Ansätze zum Erzeugen eines Schaumelements in einer ersten Schließstellung;
• 2: ein Formwerkzeug in einer ersten Schließstellung;
• 3: das aus der 2 bekannte Formwerkzeug in einer zweiten Schließstellung.

Show it:

• 1 : different approaches to producing a foam element in a first closed position;
• 2 : a mold in a first closed position;
• 3 : that from the 2 known molding tool in a second closed position.

1 in the left half of the picture shows schematically a molding tool comprising two molded parts 10. The tool is sketched here as a plunge edge tool, cf. the plunge edges 12. The molded parts 10 form a cavity 20, in which a foam blank 30 is arranged in the left half of the picture. This can be foamed in the cavity by increasing the temperature. The molding tool sketched on the right includes a channel 14 in one of the moldings 10, through which material can be supplied, see reference number A. For example, a metal melt containing, for example, blowing agent is introduced into the cavity 20 via the channel 14, which solidifies into a corresponding foam element. A first closed position S1 is sketched in both sketches.

2 shows this essentially from the 1 known molding tool, wherein the cavity is completely filled and a foam element 40 is formed. A foam blank 30, see 1 , the cavity 20 has been filled accordingly. Alternatively, the melt introduced via channel 14 has completely filled the cavity (channel 14 is in the 2 no longer shown). The cavity 20 is now expediently reduced in size. This is achieved in the present case by moving the right molded part 10 in the direction of the left molded part 10, cf. the travel direction V. In this way, the mold comes from the first closed position S1 into a second closed position S2 , cf. the 3 . In the closed position S2, the cavity 20 is reduced in size compared to the closed position S1. The foam element 40 is correspondingly compressed or is compressed/compressed at the edge. This results in the formation of a compact, closed edge layer, at least in some areas. The method expediently allows individual and low-effort production of compact, closed edge layers of foam elements.

Reference symbol list

10

molding

12

Diving edge

14

channel

20

cavity

30

blank

40

Foam element

S1

first closed position

S2

second closed position

A

Material supply

v

Travel direction

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was 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 10123899 A1 [0002]
• DE 10325819 B4 [0002]

Claims (11)

Method for producing a foam element (40), in particular a metal foam element, comprising the steps: - Producing a foam element (40) in a cavity (20) of a mold, the mold being in a first closed position (S1), in which the cavity (20) is enlarged compared to a final dimension of the foam element (40); - Moving the mold into a second closed position (S2) to reduce the size of the cavity (20), so that its final dimension is adjusted by at least partially compressing an edge region of the foam element (40). Procedure according to Claim 1 , whereby a compact/closed surface layer is formed through compression. Procedure according to Claim 1 or 2 , comprising the steps: - inserting a foam blank (30) into the mold; - Moving the mold into the first closed position (S1); - Foaming the foam blank (30) to produce the foam element (40); - Moving the mold into the second closed position (S2). Procedure according to Claim 1 or 2 , comprising the steps: - moving the mold into the first closed position (S1); - Introducing a liquid and/or gaseous material mixture into the cavity (20) to produce the foam element (40); - Moving the mold into the second closed position (S2). Method according to one of the preceding claims, comprising the step: - Reducing the size of the cavity (20) after the cavity (20) is completely filled. Method according to one of the preceding claims, comprising the step: - Using the mold for conditioning, in particular heating, the foam element (40). Method according to one of the preceding claims, wherein the volume of the cavity (20) in the first closed position (S1) is approximately 10 to 20% larger than the volume of the cavity (20) in a second closed position (S2). Component comprising at least one foam element (40), produced by a method according to one of the preceding claims. Component according to Claim 8 , wherein an edge layer of the foam element (40) has a density which is at least twice as large as a density of the core region of the foam element (40), and / or wherein a wall thickness of the edge layer does not fall below 1 mm. Component according to Claim 8 or 9 , wherein the component is a cast component in which the at least one foam element (40) is cast as an insert element. Tool, in particular plunge edge tool, in particular for carrying out a method according to one of Claims 1 until 7 , comprising a plurality of molded parts (10) which are designed to move to different closed positions (S1, S2), the tool being designed to form a cavity (20) in a first closed position (S1) for forming a foam element (40) with oversize to provide, and wherein the tool is designed to move to a second closed position (S2), in which the volume of the cavity (20) is reduced.

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