Multi-layered structural component

Abstract

The present invention relates to a multi-layered structural component (10), in particular for a motor vehicle, preferably a floor component for a motor vehicle, comprising at least two fiber layers (14) which each include a fiber material and a thermoplastic binder and are arranged one above the other in a stacking direction (S), and at least one metal layer (12) having a thickness (d) of at most 1 mm which is arranged between the two fiber layers (14), wherein the fiber layers (14) each have, at least in certain regions, a porosity of at least 75%, and wherein the structural component (10) comprises at least three metal layers (12) which are arranged one above the other in a stacking direction (S) and each have a thickness (d) of at most 1 mm, with each of the two fiber layers (14) being arranged between two metal layers (12) that are adjacent to one another in the stacking direction (S).

Claims

1. A method for manufacturing a multi-layered structural component comprising the following steps: stacking the layers, wherein at least one metal layer in the form of a metal foil having a thickness (d) of at most 1 millimeters is arranged between two fibre layers which each include a fibre material and a thermoplastic binder, and compressing the stacked layers in a mould, to produce the structural component, wherein during the step of stacking the layers at least three metal layers in the form of metal foils each having a thickness (d) of at most 1 millimeters are arranged one above the other in the stacking direction (S) such that each of the two fibre layers is arranged between two metal layers that are adjacent to one another in the stacking direction (S), wherein the fibre layers are selected such that after the step of compressing they have, at least in certain regions, a porosity of at least 75%.

2. A method according to claim 1, wherein before the step of stacking at least one of the metal layers is shaped to be three-dimensional.

3. A method according to claim 1, wherein during or after the step of stacking an additional functional component is arranged at least in certain regions between two layers of the stack, and in that the functional component is compressed together with the layers, to produce the structural component.

4. A method according to claim 1, wherein before and/or during the step of compressing at least one of the fibre layers is heated, to a temperature higher than the melting temperature or softening temperature of the thermoplastic binder but lower than the melting temperature or softening temperature of the fibre material of the fibre layer.

5. A method according to claim 4, wherein the fibre layers are fixed along their peripheral rims during the heating procedure so that the fibre layers are prevented from shrinking while being heated.

6. A method according to claim 1, wherein during the step of stacking, a cover layer is arranged on at least one outer side of the stack and is compressed together with the other layers of the stack, to produce the structural component.

7. A method according to claim 4, wherein the thermoplastic binder in the at least one fibre layer originally is in the form of fibres, which binder material fibres are molten while the at least one fibre layer is heated.

8. A method according to claim 1, wherein at least one metal layer which lies closest to the outside in the stacking direction (S) is or are micro-perforated.

9. A method according to claim 1, wherein at least one metal layer has a multi-domed shaping.

10. A method according to claim 1, wherein both metal layers, which lie closest to the outside in the stacking direction (S) are micro-perforated.

11. A method according to claim 1, wherein a plurality of the metal layers have a multi-domed shaping.

12. A method according to claim 1, wherein one metal layer which lies closest to the outside in the stacking direction (S) is micro-perforated.

13. A method according to claim 1, wherein all of the metal layers have a multi-domed shaping.

Description

(1) The present invention will be explained in more detail with reference to some preferred exemplary embodiments. In this connection:

(2) FIG. 1 shows a cross sectional view of a detail of a first exemplary embodiment of the present invention,

(3) FIG. 2 shows a cross sectional view of a detail of a second exemplary embodiment of the present invention, and

(4) FIG. 3 shows a cross sectional view of a detail of a third exemplary embodiment of the present invention.

(5) All the figures are highly schematic and simplified drawings which merely serve to illustrate the principle of the invention and in particular should not be understood as being to scale. Furthermore, the figures each show only small details of the respective structural component.

(6) Features of the second and third exemplary embodiments that correspond to those of the first exemplary embodiment are provided with reference numerals which result from adding 100 or 200, respectively, to those of the first exemplary embodiment. Where letters are used, the same reference is used in all exemplary embodiments for mutually corresponding features. The second and third exemplary embodiments are only described where they differ from the first exemplary embodiment; otherwise, the reader is referred to the description of the latter.

(7) FIG. 1 shows a structural component 10 according to a first exemplary embodiment of the invention. This structural component 10 comprises three metal layers 12 which are arranged one above the other in a stacking direction S and in the present case take the form of metal sheets or metal foils, for example of aluminium, having a thickness of at most 1 millimeters. The structural component further comprises two fibre layers 14 which respectively comprise a fibre material (e.g. glass fibres) and a thermoplastic binder (e.g. polypropylene) and are arranged to alternate with the metal layers 12, with the result that each of the two fibre layers 14 is arranged between two metal layers 12 that are adjacent to one another in the stacking direction S.

(8) The metal layers may for example have a weight per unit area of 500 g/m.sup.2 and the fibre layers a weight per unit area of approximately 1 000 g/m.sup.2, wherein the fibre layers may comprise 40 mass percent of glass fibres and 60 mass percent of polypropylene (as the thermoplastic binder).

(9) A cover layer 18 may be provided on an outer side of the structural component 10 according to the invention, and this may be for example a layer of paint or a carpet or a decorative nonwoven, in the present case having a weight per unit area of approximately 500 g/m.sup.2. This side may for example face a passenger compartment if the structural component 10 illustrated is used as a floor component in a motor vehicle.

(10) On another outer side of the structural component, a further cover layer 16, for example in the form of a porous material such as a nonwoven material, may be provided, wherein the cover nonwoven 18 illustrated, which is resistant to stone chippings, may in the present case comprise for example 25 mass percent of glass fibres and 75 mass percent of polypropylene and at the same time have a weight per unit area of approximately 500 g/m.sup.2, with the result that the structural component 10 has a weight per unit area of approximately 4.5 kg/m.sup.2 overall.

(11) In FIG. 1, as in the other exemplary embodiments (though not illustrated there), at least the two outer metal layers 12, as seen in the stacking direction, may have a micro-perforation 13, with the result that sound waves may penetrate into the inner fibre layers 14 and be absorbed there.

(12) The structural component 10 illustrated in FIG. 1 is adapted for use as a floor component or floor pan of a motor vehicle. It may completely replace a conventional floor component, which is usually made from an individual solid metal plate on which various material layers are subsequently provided for sound absorption or noise reduction and for generating resistance to stone chippings and for purposes of decoration or comfort, and which has a weight per unit area, including these additional layers, of approximately 10 kg/m.sup.2. By comparison with a conventional floor component of this kind, having a solid metal plate, a weight saving of more than 50% may be achieved using the structural component according to the invention, in which the functional layers for sound absorption, etc. are already integrated.

(13) In the structural component 110 illustrated in FIG. 2, the metal layers 112 are each provided with a multi-domed impression in order to simplify a three-dimensional shaping (not illustrated) of the structural component (such as the formation of a trough-like depression or an upwardly extended rim in the structural component). This is particularly useful in the case of a particularly large number of metal layers or a particularly pronounced desired three-dimensional shaping of the multi-layered structural component.

(14) Here, the multi-domed shaping comprises a pattern, impressed into the metal layers, of elevations 112.1 and depressions 112.2 which resemble hemispheres and are arranged alternately in the manner of a checkerboard, wherein the individual domes (spherical portions) in the present example have a dome diameter D of approximately 5 millimeters and a dome height H of approximately 2.5 millimeters, and thus lie in the region of a few millimeters.

(15) During manufacture, the multi-dome-shaped metal layers 112 may be stacked with the fibre layers 114 and then compressed and where appropriate shaped, with the multi-domed shaping simplifying the shaping of the metal layers (with radii of curvature or dimensions of the structures produced by the shaping in the region of several centimeters) and hence improving the homogeneity of the layered structure in the structural component 110.

(16) In contrast to the illustration in FIG. 2, it is possible here for the multi-domed shaping of the metal layers 112 not to be made in the cover layers 116, 118, and for the respectively outer surfaces of the cover layers 116, 118 to be planar, unlike the situation illustrated.

(17) As illustrated in FIG. 3, it is also possible to integrate in a structural component 210 according to the invention further components, such as a functional component 220, which in the present case takes the form of a hollow profile and serves as a reinforcing component. During manufacture, two stacks, each comprising three metal layers 212, two fibre layers 214 and a cover layer 216 and 218 respectively, are arranged in mirror symmetry to one another, one above and one below the functional component 220 as seen in the stacking direction S, and are compressed with the latter to produce the structural component 210.

(18) Additional functional components of this kind may on the one hand affect the strength, flexural rigidity, etc. of the structural component in a desirable manner, but may also serve other functions such as providing fixing structures for attaching the structural component to further components, for example of a motor vehicle.

(19) In all the exemplary embodiments, an adhesion promoter may be provided in each case between directly adjacent layers and on the surface of the functional component 220 in order to enable or simplify a form-fitting connection over connecting areas between the layers, or between the layers and the functional component.

(20) Structural components according to the invention may be used not only in the motor vehicle sector, for example as floor components (to replace conventional floor pans), frame or bodywork components, but also for example in plasterboard construction.