DE102007006156B3 - Making composite with component bonded to foamed body, for e.g. reinforcement, introduces thermally-foamable pressing into cavity of component, deforms, bonds and heats - Google Patents

Abstract

A foamable pressing (2) is brought into a cavity (3a) of the component (1a). The pressing and component make loose contact; the cavity volume exceeds that of the pressing. The component is deformed such that the component and pressing undergo interlocking and/or frictional bonding. The pressing is foamed by supplying heat externally. In an otherwise similar process, the foamed pressing includes the cavity into which the component is introduced. The deformation is caused by extrusion. Heat treatment follows immediately, to induce foaming. In a further variant of the process, a foamable powder is used in place of the foamable pressing. The component is a thermal conductor, through which heat is supplied to the foamable material. A first layer of foamable material used to make the composite, has a lower liquidus temperature than a second layer. The first layer largely comprises compacted aluminum powder. The second is aluminum or aluminum alloy. An independent claim IS INCLUDED FOR an intermediate product so produced.

Description

The The present invention relates to methods for producing a composite body which contains at least one component, that with a foam body and an intermediate for producing a composite body. Especially the present invention finds application for metallic extruded profiles with massive exterior and porous interior structure, for example, extruded aluminum profiles with porous aluminum cores.

It It is considered well known that metal profiles with metal foam, in particular aluminum foam, partially or completely filled. Often done the foaming in a heat treatment process; Alternatively, however, is the bonding of prefabricated foam cores known in metal profiles. Foamy or foamed with foam Profiles are mostly semi-finished products, which then continue be processed and in larger assemblies, For example, in mechanical engineering or in the manufacture of vehicle bodies Find application.

Of the Use of the metal foam consists in a stiffening of the metal profiles and / or an improvement in the damping behavior of the foamed components compared to conventional components. To opposite hollow profiles At least equivalent properties can be achieved in the Use of metal foams the thicknesses of the profile walls the foaming Metal profiles are reduced. Thus, metal foams become particular Used in areas where lightweight construction while retaining or Improvement of the rigidity of a component is operated.

The foaming Steel parts either undergo a heat treatment process a powder metallurgical metal foaming process or in a casting-like Process by a melt metallurgical metal foaming process in Range of melting temperature of the metal foam. Be the steel parts Foamed with aluminum foam, the steel part remains intact since the melting temperature of steel is usually well above that of Melting temperature of aluminum is. Be through the heat treatment process or the casting-like Process changes the steel structure and its properties at atomic lattice level, The metal foam can also be glued into the steel part.

Aluminum parts, in particular aluminum profiles are compared to steel profiles relatively easy. Nevertheless, there is a need, even with aluminum profiles to reduce the weight further. This is due to the reduction the thickness of the profile walls feasible, with component areas with reduced wall thickness then by Foamed metal foam become. Aluminum profiles can so far only be foamed with aluminum foam, if the melting temperatures and melting temperature intervals are very far apart. There the temperature differences are usually not more than 50 K, is the foaming so far only limited possible.

One foaming in usual Heat treatment units like chamber furnaces is difficult because the aluminum parts are usually transferred to their doughy state. The material is then no longer dimensionally stable, resulting in the geometric Change the properties of the component, resulting in a deterioration in dimensional stability and frequent reworking leads. This effect is especially when foaming very thin-walled and large volume Aluminum profiles observed, but just in these profiles the potential for weight reduction is greatest.

difficult is the foaming, when the contact between the foamable molding material and the auszuschäumenden or to be lathered Component is bad. This is the case when the foamable molding material is only loosely in abutment with the component. Few point or linear Plants are the cause of a bad heat transfer between the component and the foamable Mold material, which can lead to melting of the component before the foamable molding material sufficiently frothed is.

The DE 601 03 017 T2 discloses a method for producing a composite body wherein metal powder is poured onto a lower metal band. The powder layer deposited on the lower metal strip is covered by an upper metal strip. The semi-finished product thus produced passes through a preheating furnace and is subsequently compacted between two rolls, so that a later foamable laminate is produced, in which the individual layers are connected to one another. Thus, said document discloses an intermediate product according to the preamble of claim 9.

The DE 199 11 213 C1 illustrates the foaming of a metal powder layer in an oven, wherein the metal powder layer between a cover plate and a pipe or a connecting rod is arranged.

The DE 102 60 419 A1 deals with the compaction of foamable metal powder, wherein a powder mixture is filled into an open pan, which has a lower plate body as the bottom. An upper plate body is placed, so that a container is formed, which then ßend evacuated and rolled.

It object of the present invention, process for the preparation a composite body, which contains at least one component, that with a foam body and to provide an intermediate for producing a composite body, in which premature melting of the component can be prevented can use time-consuming and costly adhesive methods without come.

The The aforementioned object is achieved by a method for Production of a composite body according to claim 1.

Compacts the foamable Material are produced, are particularly suitable for low cost Manufacture and allow in a simple way a by weight and compression of the compact defined amount of foamable Loose material with the component. By the transformation the component and the formation of a positive and / or non-positive connection between the component and the compact is a maximum contact surface between reached the component and the compact. This will heat transfer improved between the component and the compact and a premature Melting of the component during foaming prevented.

In front the forming step, the component has a cavity into which the Pressling is introduced, wherein a volume of the cavity is greater than a volume of the compact. As a result, composites are produced, whose inner layers are made of foamed material.

The The aforementioned object is further achieved by a method for Production of a composite body according to claim Second

Of the Pressling has a cavity before the forming step, in the the component is inserted, wherein a volume of the cavity is greater than a volume of the component. Here are composite bodies can be produced, their outer layers from foamed Material exist.

Preferably the deformation is achieved by means of an extrusion process. This allows a inexpensive and reliable Production of the composite body, or an intermediate product before the beginning of the foaming step possible.

The The aforementioned object is further achieved by a method for Production of a composite body according to claim 5th

There the compression is achieved by means of an extrusion process, is a cost effective and reliable Production of the composite body, or an intermediate prior to the start of the foaming step possible.

Out expandable Material existing powder is preferably used for composite bodies in which because of the component geometry or the batch size to be produced Use of compacts does not make sense. By the compression of the Powder around a form and / or non-positive connection to achieve with the component, as described above, the heat transfer between the component and the foamable Material drastically improved, resulting in external heat input Premature melting of the component is prevented during foaming.

According to one preferred embodiment the component is reshaped, and by the deformation of the component the powder is compressed. This may indicate the use of a separate compression device for the powder, for example be dispensed with in the form of a separate stamp.

Further preferred embodiments of inventive method are in the further dependent claims explained.

Furthermore the above object is achieved by an intermediate product according to the invention according to claim 9th

By this intermediate is particularly composite by means of foaming reliable produced, as by the positive and / or non-positive connection the two layers heat transfer is improved and premature melting of the layer not foamable material is prevented.

Preferably the first layer has a lower liquidus temperature than the second layer. A transition the second layer of non-foamable material in their continuous homogeneous phase before foaming the first layer is thereby prevented.

According to one another preferred embodiment the first layer consists mainly of compacted aluminum powder, and the second layer consists of Aluminum or an aluminum alloy. This allows a Production of particularly lightweight composites.

Further preferred embodiments of the inventive intermediate are in the further dependent claims explained.

The The present invention will be described below with reference to preferred embodiments in conjunction with the associated Figures closer explained. In these show:

1 a schematic representation of an initial state in which a compact of foamable material is inserted into a component;

2 a schematic representation of an intermediate product before the start of a foaming process;

3 a schematic representation of an initial state in which a component is inserted in a compact of foamable material;

4 a schematic representation of an intermediate in a foam mold before the start of a foaming process;

5 a schematic representation of an intermediate product to be foamed and a component to be foamed; and

6 a schematic representation of an intermediate product with a shrink edge.

In the 1 and 3 Two different schematic representations of initial states are shown.

In 1 denotes the reference numeral 1a a auszuschäumendes component, which is preferably a metal component such. B. can act as an aluminum profile. Preferably, the auszuschäumende component 1a cylindrical and has at least one cavity in its interior 3a on.

In this cavity 3a is foamable material 2 brought in. In the embodiment shown, the foamable material 2 previously pressed into a compact. The contour of the compact essentially corresponds to the contour of the cavity 3a , However, the volume of the compact is less than the volume of the cavity 3a , so that an outer wall of the compact with an inner wall of the component 1a is loosely attached, in 1 a small residual cavity at the top of the original cavity 3a arises.

Is the use of a compact of foamable material not possible, for example due to geometric conditions, such as undercuts to be filled or discontinuities in the contour of the cavity 3a , Powder consisting of the foamable material may be used instead of the compact. This powder is in the cavity 3a filled in and is in the initial state loosely in contact with the inner wall of auszuschäumenden component 1a ,

In contrast to 1 is in 3 an embodiment shown in which a compact of foamable material 2 a cavity 3b having. In this cavity 3b is a component to be foamed 1b introduced, taking for the contours and volumes of the cavity 3b and the component to be foamed 1b the same applies as for the contours and volumes of the cavity 3a and the compact of foamable material 2 in 1 , Also in the in 3 Initial state shown are the compact and the component to be foamed 1b loosely attached.

It is also conceivable that it is the foamable material 2 in 3 is not a compact, but powder, which is introduced into a mold, not shown, wherein the component to be foamed 1b Loosely in contact with the powder.

The terms "component auszuschäumendes 1a "and" to umschäumendes component 1b In particular, extruded profiles, preferably made of aluminum or an aluminum alloy, which are at least partially foamed and / or at least partially foamed, have cross-sectional shapes of these extruded profiles which can be shaped as desired, as long as they form a force and / or positive connection with the foamable material as explained below 2 enable. This is preferably achieved by round or square, preferably square cross-sections.

Preferably, the liquidus temperature of the component to be expanded is 1a or of the component to be foamed 1b higher than the liquidus temperature of the foamable material 2 , The components 1a and 1b serve in particular as a heat conductor, by the heat to activate the foamable material 2 , And thus the start of the foaming process, from an external heat source on the not yet foamed foamable material 2 can and will be transmitted.

It is also conceivable, the auszuschäumende component 1a or the component to be foamed 1b to carry out in several parts. Thus, it is possible to insert the compact in a first component half and this then by a second component half, z. B. to close a lid. For cylindrical components, it is advisable to insert the compact laterally along the cylinder axis. Conversely, this also applies to a multipart or cylindrical compact in 3 and the corresponding component to be foamed 1b ,

Starting from the initial state is the component 1a . 1b transformed so that it enters into a positive and / or non-positive connection with the compact. In the case of a foamable component 1a this can be done by applying force perpendicular to an outer surface of said component 1a take place, wherein the component 1a is plastically deformed. In this case, the residual cavity ideally decreases so far until all areas of the inner surface of the auszuschäumenden component 1a in positive and / or non-positive connection with the foamable material 2 stand.

Conversely, the component to be foamed 1b be widened until its outer surface is ideally completely made with the hollow compact, ie the inner surface thereof in positive and / or non-positive engagement. Is this the part to be foamed? 1b tubular or has the shape of a hollow cylinder, the expansion can be done for example by an expanding mandrel or hydroforming.

When using powder as a foamable material 2 is preferably by the deformation of the component 1a . 1b the powder is compressed, so that said component 1a . 1b and the compressed powder form a positive and / or non-positive connection. It is also conceivable that the powder together with the component to be foamed 1b is introduced into a mold, and in this with the said component 1b is pressed. Preferably comes in the forming of the component 1a . 1b and / or the compression of the powder is an extrusion process used. Preferably, immediately after extrusion, the extruded intermediate product is subjected to a heat treatment in which the foamable and previously extruded material 2 is foamed.

In the 2 and 4 are thus manufactured intermediates 4 shown schematically how they are present after the deformation or compression and before the start of the foaming process.

The embodiment of the intermediate product 4 in 2 shows an internal layer of foamable material 2 and an outer layer of non-foamable material of the foamable component 1a , For example, an aluminum profile. Both layers are positively and / or non-positively connected. In 2 a hollow body is shown in which the foamable material 2 hollow pressed. This can be achieved both by a correspondingly pre-pressed compact and by compressing powder of foamable material 2 by a stamp or similar.

In contrast to 2 exists in the in 4 embodiment shown, the outer layer of the intermediate product of foamable material 2 while the inner layer of non-foamable material of the component to be foamed 1b , which is tubular, consists. Because the foamable material 2 outside the component to be foamed 1b is the intermediate product 4 in a foam form 5 introduced to counteract the pressure generated during the foaming process, and to give the composite body when foaming the desired outer contour.

In 5 is a schematic representation of an intermediate product to be foamed and a component to be foamed 1a . 1b shown. Between the two components 1a . 1b is the foamable material 2 introduced positive and / or non-positive. As well as in the 3 and 4 shown, the component to be foamed 1b have both a hollow and a massive cross-section.

When using different materials is with different expansion coefficients of the foamable material 2 or of the foamed material and the components 1a . 1b to count. Advantageously, this problem is met by walls of auszuschäumenden component 1a or of the component to be foamed 1b attached to the foamable material 2 be bordered, provided with projections or undercuts.

For a foamable component 1a is such an advantageous embodiment in 6 shown. Perpendicular to an inner surface of the extruded profile having a square cross-section extends along a longitudinal axis in the interior thereof, a projection of a shrinking edge 6 forms. This shrinking edge 6 protrudes into the foamable material 2 into, which is due to shrinkage stress due to different expansion coefficients from the positive connection a frictional connection. Accordingly, other projections or undercuts, which extend at least along a partial region of the longitudinal axis, conceivable.

As a foamable material 2 For example, a mixture of aluminum powder and a metal hydride, for. As titanium hydride used. Knowing the foaming rate of the foamable material 2 , as well as the amount of foamable material introduced and the total volume to be foamed, the density of the foamed material in the finished composite can be calculated in advance. Achievable densities are below 1 g / cm ³ for aluminum foam, and still allow very good vibration and Energeaeabsorpitionseigenschaften at low for such composites Weight.

The preferred temperature range for extruding aluminum alloys is between 300 to 550 ° C. With regard to the extruded intermediate product, there are limitations due to the decomposition temperature of the blowing agent of the foamable material 2 so that the extrusion temperatures should not exceed 500 ° C when using the propellant titanium hydride preferably used. It must be emphasized that even at temperatures lower than 300 ° C (even room temperature), the extrusion process can be carried out, but at the lower temperatures, the connection between the component 1a . 1b and the foamable material 2 significantly worse.

For preferred aluminum materials, yield stresses range between about 20 N / mm ² (Al99.5) and nearly 60 N / mm ² (AlZn5.5MgCu). Depending on various parameters, in particular the strand cross-section to be generated and the temperature, the yield stress of the intermediate product to be extruded and the necessary extrusion forces are calculated.

The preceding exemplary embodiments describe, inter alia, a method for producing a composite body, which comprises at least one component 1a . 1b contains, which is connected to a foam body, comprising the following method steps: assigning a foamable material 2 existing compacts to the component 1a . 1b , wherein the compact and the component 1a . 1b be loosely engaged, reshaping of the component 1a . 1b such that the component 1a . 1b forms a positive and / or non-positive connection with the compact, and foaming of the foamable material 2 existing compacts by external heat input, as well as an intermediate for producing a composite body. Due to the positive and / or non-positive connection, it is particularly possible auszuschäumen aluminum profiles with aluminum foam, without the profile body is transferred to the doughy state.

Through appropriate measures, such as the use of a mold, and components can 1a foamed, which are already in the doughy state.

Claims (11)

Method for producing a composite body comprising at least one component ( 1a ), which is connected to a foam body, comprising the following process steps: - introducing a foamable material ( 2 ) existing compact in a cavity ( 3a ) of the component ( 1a ), wherein the compact and the component ( 1a ) and a volume of the cavity ( 3a ) is greater than a volume of the compact, - forming the component ( 1a ) such that the component ( 1a ) enters into a positive and / or non-positive connection with the compact, and - foaming of the foamable material ( 2 ) existing compact by external heat. Method for producing a composite body comprising at least one component ( 1b ), which is connected to a foam body, comprising the following process steps: - introducing the component ( 1b ) into a cavity ( 3b ) of a foamable material ( 2 ) existing compact, wherein the compact and the component ( 1b ) and a volume of the cavity ( 3b ) greater than a volume of the component ( 1b ), - reshaping of the component ( 1b ) such that the component ( 1b ) enters into a positive and / or non-positive connection with the compact, and - foaming of the foamable material ( 2 ) existing compact by external heat. The method of claim 1 or 2, wherein the forming achieved by extrusion. A method according to claim 3, wherein immediately after the extrusion, the extruded intermediate product is subjected to a heat treatment in which the foamable material ( 2 ) is foamed. Method for producing a composite body comprising at least one component ( 1a . 1b ), which is connected to a foam body, comprising the following method steps: - Assigning a foamable material ( 2 ) existing powder to the component ( 1a . 1b ), wherein the powder and the component ( 1a . 1b ), by compressing the powder in such a way that the component ( 1a . 1b ) forms a positive and / or non-positive connection with the compressed powder, and - foaming the foamable material ( 2 ), compressed powder by external heat. Method according to claim 5, wherein the component ( 1a ) before the compression step a cavity ( 3a ), in which the powder is filled. The method of claim 5 or 6, wherein immediately after extrusion, the extruded intermediate product of a heat treatment in which the foamable material ( 2 ) is foamed. Method according to at least one of claims 1 to 7, wherein the component ( 1a . 1b ) is a heat conductor through which the foamable material ( 2 ) the heat is supplied to start the foaming step. Intermediate for producing a composite body, in particular according to one of claims 1 to 8, with a first layer of foamable material ( 2 ) and a second layer of non-foamable material, wherein both layers are positively and / or non-positively connected to each other, characterized in that the first layer is a compact of foamable material ( 2 ), which is outside of a second layer forming, at least partially to be foamed member ( 1b ) is arranged and connected to this. Intermediate product according to claim 9, characterized that the first layer has a lower liquidus temperature than that second layer has. Intermediate after spoke 9 or 10, by characterized in that the first layer consists mainly of compacted aluminum powder, and the second layer of aluminum or an aluminum alloy consists.