EP1079948A1

EP1079948A1 - Composite part containing metallic foam and method for producing said composite part

Info

Publication number: EP1079948A1
Application number: EP00915140A
Authority: EP
Inventors: Olaf Abels
Original assignee: ZF Lemfoerder GmbH
Current assignee: ZF Lemfoerder GmbH
Priority date: 1999-03-12
Filing date: 2000-03-07
Publication date: 2001-03-07
Anticipated expiration: 2020-03-07
Also published as: US6444330B1; WO2000054911A1; ES2240077T3; EP1079948B1; DE19911213C1

Abstract

The invention relates to a composite part (1) consisting of at least two solid metal sheet parts (4, 5) which face each other with a layer of metallic powder to be expanded between them. The composite part has additional reinforcing elements (9) in individual cross-sectional areas, said elements being connected to the expanded layer of metallic powder (6, 7) that surrounds them with a form fit. Said expanded layer is connected to the outlying solid metal sheet parts in such a way that they cannot be separated non-destructively. The invention also relates to a method for producing the inventive composite part. According to said method, each solid metal sheet part (4, 5) is provided with a metallic powder layer (6, 7). The two sheet parts (4, 5) are then arranged on top of each other with the sides that have been provided with the metallic powder layer (6 and 7) facing towards each other. The thus superposed sheet parts are heated by applying heat in such a way that a joint that cannot be separated non-destructively is produced between the metallic powder layers (6, 7) facing each other by means of a heat-dependent expanding process.

Description

COMPOSITE COMPONENT CONTAINING METAL FOAM AND METHOD FOR PRODUCING THE COMPOSITE COMPONENT

Description:

The invention relates to a composite component which consists of at least two opposing solid metal sheet metal parts and a metal powder layer to be foamed which is arranged between the sheet metal parts, and to a method for producing the composite component.

Nerbund components of the type described at the outset are used in various industrial areas and in particular in automotive engineering, since they have a relatively low mass with high rigidity.

The method for producing such composite components usually takes place in several steps. First, a Nerbund semifinished product is produced from solid metal sheet metal parts and the metal powder layer, for example by a roll cladding process. The rolling process brings about a metallic bond between the central metal powder layer and the inner sides of the solid metal sheet metal plate parts covering this metal powder layer. After the rolling process has ended, the sandwich-like plate material can pass through

Punching is broken down into individual parts, then the individual parts are given a changed shape, for example by deep drawing or similar processing steps. Here, certain boundary conditions must be observed, such as are protected under DE 196 12 781 Cl, for example. In this document it is described that after shaping the sandwich-like semi-finished product this is placed in a foaming mold adapted to a wall on its end contoured side for final production and is subjected to a heat treatment in a suitable manner. Due to the fact that a blowing agent is added to the metal powder layer, foaming of the metal powder layer is produced by the action of heat. This foaming process is ended when the second solid metallic cover layer has come to rest on the further contact surface of the foaming mold.

The sequence of manufacturing steps described above makes it possible to manufacture lightweight metal components for constant dimensionally stable series production, in particular in vehicle construction, from flat, sandwich-like semi-finished products.

In addition, manufacturing processes are known in the prior art, in which metal powder is foamed in a corresponding form and the semi-finished product thus produced is later introduced into a casting mold and then, for example by die casting, is finished to form a non-composite component with a foam core and an external, solid metal shell. Such a manufacturing method is known for example from DE 195 01 508 Cl.

With the different manufacturing processes described above, there is indeed the possibility of producing composite components that allow increased energy absorption compared to solid components and that have much better damping with regard to acoustic conditions. However, with the methods described, a special partial stiffening of the composite components to provide increased rigidity adapted to external conditions is not possible, since additional reinforcing elements would only have to be introduced in certain cross sections of the composite component. In the prior art, the introduction of such reinforcing elements can only be achieved by welded or welded structures. With the aid of such method steps, it is possible to insert reinforcing elements between two solid metallic cover layers and to lock them in a form-fitting manner. Such a manufacturing process is, however Production-technically complex and therefore associated with increased manufacturing costs.

The technical problem of the present invention is therefore to further develop a composite component of the generic type in such a way that the increased requirements, in particular in automotive vehicle technology, with regard to increased rigidity with a reduced component weight, and to provide a method for its production.

This technical problem is solved according to the invention in that the

Composite component in individual cross-sectional areas has additional stiffening elements which are positively connected to the surrounding foamed metal powder layer, which in turn is non-destructively and inseparably connected to the external solid metal sheet metal parts.

This special design makes it possible for the first time to optimally adapt the resistive moments that counteract these to the particular stresses occurring within chassis components. This can be done on the one hand by the different design of the internal stiffening elements, for example by making them from square profiles, flat materials or U-profiles. In addition, it is possible to adjust the stiffening elements in their material selection accordingly, so that, for example, materials such as titanium or the like can also be used in the stiffening elements under the highest loads.

Compared to the prior art, the method according to the invention for producing composite components of this type only enables the one according to the invention

Design of the composite components, in addition, the manufacturing process is characterized by the sequence of simple and inexpensive process steps. In particular, the method for producing a composite component, which at least according to the features of claim 1 for implementation requires two sheet metal parts lying opposite one another and a foamable metal powder layer arranged between the sheet metal parts, described by the process steps that a solid metal sheet part is provided with a metal powder layer, then the two sheet metal parts with their side provided with the metal powder layer are arranged one above the other and finally the sheet metal parts lying one above the other are heated by supplying heat in such a way that the supply of heat causes a foaming process in the mutually facing metal powder layers, which causes an inseparable connection of the metal powder layers.

This method thus "glues" the facing one another

Metal powder layers reached. In addition, this method makes it possible to arrange additional stiffening elements in the form of sheet metal molded parts or profiles between them in certain partial areas of the composite component before the heating process of the sheet metal parts lying on top of one another, which in the subsequent foaming process is inseparable and non-destructively from the foamed one

Metal layer powder are connected. The result is a composite component which is equipped with a particularly high section modulus in some areas and which can be produced particularly inexpensively.

In the following, an exemplary embodiment of the composite component according to the invention is explained in more detail with reference to the attached drawing and the method for producing the composite component is described.

It shows:

FIG. 1 shows a cross-sectional view through a motor vehicle wishbone as an example of a composite component according to the invention,

Figure 2 shows sectional views along the line A-A and B-B of Figure 1 and

FIG. 3 shows an enlarged detailed view of the detail X from FIG. 1. The composite component, designated in its entirety by 1, has two supporting tubes 2 and 3. The supporting tubes 2 and 3 are connected to one another by an upper cover plate 4 and a lower cover plate 5. There is one on each of the inner sides of the cover plates 4 and 5 facing the supporting tubes 2 and 3

Rolled metal powder layer 6 and 7. In the area between the tubes 2 and 3, the cover plates 4 and 5 are formed so that a connecting web 8 results. The cover plates 4 and 5 are formed in the region of the connecting web so that there is a cavity between them. In this exemplary embodiment, a stiffening element in the form of a connecting rod 9 is inserted into this cavity. This connecting rod is designed so that it has three areas I, II, III with an annular cross section and two areas IV and V with a substantially rectangular cross section. The cross-sectional design can be seen clearly in FIG. 2. From this figure it follows that the cover plates 4 and 5 on their respective outer edges of the connecting web 8

Metal powder layers lie one on top of the other and the metal powder layers 6 and 7 in the interior of the connecting web 8 completely enclose the connecting rod 9.

The different design of the cross sections in the areas I to III, or IV and V is due to different requirements for the section modulus in the area of the composite component. In this context, it is of course conceivable to give the connecting rod 9 instead of the round or rectangular cross-sections shown here, depending on the requirements, square or any other cross-section.

From the representation of Figure 3 it is clear once again that the metal powder layers applied to the respective cover plates completely enclose both the supporting tubes 2 and 3 and the connecting rod 9 in the finished state, so that a positive, non-destructive inseparable connection between the individual components of the Composite component 1 is made. The manufacturing process for the composite component 1 shown here is divided into the following process steps:

First, the lower cover plate 5 and the upper cover plate 4 are coated with a metal powder layer 6 and 7, respectively. This coating is usually done by a rolling process, in the context of which a firm connection between the

Metal powder layer and the cover plate is made. The metal powder layer can consist, for example, of aluminum powder with a corresponding blowing agent, for example titanium hydride (TiH ₂ ). After the rolling process, the cover plates 4 and 5 are provided with the contour shown in FIG. 1 in a forming process. This contour is characterized in that it has two areas 10 and 11 for receiving the supporting tubes 2 and 3 and an area in between for receiving the connecting rod 9. If the upper cover plate 4 and the lower cover plate 5 are placed one on top of the other, there are cavities for receiving the corresponding pipes 2 and 3 and the connecting rod 9. The folding together of the individual components of the composite component forms a further process step in the production process.

If the individual components of the composite component are put together in the manner described, the composite component 1 is then heated, for example in an oven, to a temperature required for the foaming of the metal powder layer, which can reach values which are just below the melting temperature of the cover sheets. Temperatures between about 600 ° C and 800 ° C are possible. The blowing agent contained in the metal powder layers releases gases which are similar to foaming polyurethane foam and which let the aluminum powder mixture foam. As part of the foaming process, a positive connection between the metal powder and the tubes 2 and 3 or

Connection linkage 9 brought about. AlMgSil, for example, can be used as the material for the cover plates.

FIG. 3 shows an enlarged view that the metal powder layer completely fills the cavities between the cover plates 4 and 5 and the inner stiffening components 2, 3 and 9. At the same time it becomes a fixed one Connection in the form of an adhesive in the outer regions of the cover plates 4 and 5 at the points at which the metal powder layers 6 and 7 lie directly on one another. After the composite component has cooled, the result is a compact chassis component which is optimally adapted to the framework conditions with regard to strength and lightness and which is characterized by simple and inexpensive manufacture.

In addition, it is of course conceivable within the scope of the implementation of the method according to the invention to additionally foam, for example for rubber bearings, such as are used in control arms, into the composite component without an additional operation of welding the recordings to the composite component. In addition, the heat treatment of the composite component can be controlled in such a way that it is combined with the heat treatments of aluminum materials that are used anyway. This additionally increases the economic efficiency of producing the components according to the invention. Adequate strength is achieved on the one hand through the use of the internal stiffening parts, at the same time the metal foam used brings about an improvement in the acoustic properties, since it has much better damping than conventional solid materials.

In addition to the improved acoustic properties, the metal foam also has the ability to absorb more energy due to its porosity. This can be advantageous for the deformation behavior of composite components according to the invention, for example in the event of a crash.

Reference symbol list:

1. Composite component

2. supporting pipe

3. supporting pipe

4. Upper cover plate

5. lower cover plate

6. Metal powder layer

7. Metal powder layer

8. Connecting bridge

9. Linkage linkage

10. Area

11. Area

Claims

Claims:

1. Composite component, which consists of at least two opposing solid metal sheet metal parts and a metal powder layer to be foamed arranged between the sheet metal parts, characterized in that the composite component has in individual cross-sectional areas additional stiffening elements which are positively connected to the surrounding foamed metal powder layer, which in turn is non-destructively inseparable is connected to the external solid metal sheet parts.

2. A method for producing a composite component which consists of at least two opposing solid metal sheet parts and a metal powder layer to be foamed which is arranged between the sheet parts, characterized in that a solid metal sheet part (4, 5) is provided with a metal powder layer (6, 7), then the two sheet metal parts (4, 5) with their side provided with the metal powder layer (6 and 7) are arranged one above the other, and that the sheet metal parts lying one above the other are then heated by the supply of heat in such a way that between the metal powder layers (6, 7 ) a non-destructive inseparable connection is created by a heat-related foaming process.

3. The method according to claim 2, characterized in that between the two sheet metal parts (4, 5) before the heating process, at least one further sheet metal part (9) is inserted.

4. The method according to claim 2 or 3, characterized in that the metal powder layers (6, 7) consist of foamable aluminum.