Composite Component for a Vehicle, in Particular a Motor Vehicle, and Method for the Production of a Composite Component

Abstract

A composite component for a vehicle has a core layer made from a theiinoplastic plastic foam and at least one cover layer which is connected to the core layer. The core layer has a higher density in one region than the density of the semi-finished core layer. The cover layer formed from a fiber-reinforced plastic is connected in the region of higher density to at least one joining element by friction welding.

Claims

1.-8. (canceled)

9. A composite component for a vehicle, comprising: a core layer, wherein the core layer is a thermoplastic plastic foam; and a cover layer, wherein the cover layer is connected to the core layer and wherein the cover layer is a fiber-reinforced plastic; wherein the core layer has a higher density in a first region than in a second region and wherein the cover layer is connected at a position of the first region of the higher density of the core layer to a plastic joining element by friction welding; wherein the fiber-reinforced plastic of the cover layer is a thermoplastic; wherein the thermoplastic plastic foam of the core layer is polyethylene terephthalate.

10. The composite component for a vehicle according to claim 9, wherein the thermoplastic of the cover layer is polypropylene.

11. The composite component for a vehicle according to claim 9, wherein the core layer has a higher melting point than the cover layer.

12. The composite component for a vehicle according to claim 9, wherein the friction welding is carried out with a welding amplitude of 1 millimeter.

13. The composite component for a vehicle according to claim 10, wherein a temperature of the friction welding is in a range from 160 degrees Celsius to 250 degrees Celsius.

14. A method for production of a composite component of a vehicle, wherein the composite component includes: a core layer, wherein the core layer is a thermoplastic plastic foam; and a cover layer, wherein the cover layer is connected to the core layer and wherein the cover layer is a fiber-reinforced plastic; wherein the core layer has a higher density in a first region than in a second region; wherein the fiber-reinforced plastic of the cover layer is a thermoplastic; wherein the thermoplastic plastic foam of the core layer is polyethylene terephthalate; and comprising the step of: connecting the cover layer at a position of the first region of the higher density of the core layer to a plastic joining element by friction welding.

15. The method according to claim 14, wherein the thermoplastic of the cover layer is polypropylene.

16. The method according to claim 14, wherein the core layer has a higher melting point than the cover layer.

17. The method according to claim 14, wherein the friction welding is carried out with a welding amplitude of 1 millimeter.

18. The method according to claim 15, wherein a temperature of the friction welding is in a range from 160 degrees Celsius to 250 degrees Celsius.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a schematic sectional view through a composite component for a vehicle, having a core layer made from a thermoplastic plastic foam and at least one cover layer connected to the core layer, wherein the core layer has a higher density in at least one first partial region than in at least one second partial region which is adjacent to the first partial region and wherein the cover layer formed from a fiber-reinforced plastic is connected to at least one joining element in the first partial region by friction welding; and

[0024] FIG. 2 is a further schematic sectional view through the composite component which is connected to respective joining elements by means of friction welding.

DETAILED DESCRIPTION OF THE DRAWINGS

[0025] In the figures, the same or functionally identical elements are provided with the same reference numerals.

[0026] FIG. 1 is a schematic sectional view of a composite component in the form of a sandwich composite component which is produced from a layer composite referred to with 10. The layer composite 10 and thus the composite component comprise a core layer 12 made from a thermoplastic plastic foam. The core layer 12 is preferably made from polyethylene terephthalate (PET) and is thus formed as a PET foam core. The layer composite 10 furthermore comprises respective cover layers 14 and 16 between which the core layer 12 is arranged. The respective cover layer 14 or 16 is formed from a fiber-reinforced plastic, wherein the plastic of the cover layer 14 or 16 is preferably a thermoplastic and in particular polypropylene (PP). The plastic of the respective cover layer 14 or 16 is thus a matrix or a matrix material into which reinforcing fibers are embedded. These reinforcing fibers are preferably glass fibers, natural fibers, aramid fibers and/or carbon fibers. The respective cover layer 14 or 16 can, for example, be formed from a hybrid non-woven material, organic sheet or hybrid woven fabric.

[0027] At least one bonding layer 18 or 20 is arranged between the respective cover layer 14 or 16 and the core layer 12, via which bonding layer the respective cover layer 14 or 16 is connected to the core layer 12. The respective bonding layer 18 or 20 is also referred to as a melt layer since it is liquefied or melted, for example, during the production of the composite component or of the layer composite 10. The respective bonding layer 18 or 20 is formed, for example, by the plastic of the respective cover layer 14 or 16 or by an additionally provided plastic or from an adhesive, in particular reactive adhesive, which is provided in addition to the respective plastic of the cover layers 14 and 16 and the core layer 12. The connection of the cover layers 14 and 16 to the core layer 12 takes place via the respective bonding layer 18.

[0028] Overall, it can be seen from FIG. 1 that a sandwich composite having a thermoplastic foam core and fiber-reinforced thermoplastic cover layers 14 and 16 is formed by the layer composite 10. For example, a panelling part, in particular interior panelling part, of a vehicle such as a motor vehicle and in particular a passenger vehicle, for example, is produced from the layer composite 10.

[0029] The composite layer 10 is introduced, for example, as a semi-finished product into a pressing tool which comprises two tool halves. The tool halves are, for example, arranged opposite each other and can be moved towards each other and away from each other. If the layer composite 10 (semi-finished product) is located, for example, between the tool halves, these are moved towards each other, i.e., closed, as a result of which the layer composite 10 is pressed, for example. The composite component is thus a press component which is pressed by means of the pressing tool and is formed at the same time or subsequently by means of a forming tool.

[0030] The layer composite 10 can optionally comprise a decorative layer 22 which is arranged on the cover layer 14 and is connected to the cover layer 14, for example. The decorative layer 22 is arranged on a visible side 24 of the composite component. Such a visible side is to be understood to be a side which, in the finished manufactured state of the vehicle, is visually perceptible to viewers of this vehicle, in particular to passengers in the interior space of the vehicle. The decorative layer 22 can thus provide an advantageous visual impression of the composite component as a whole. Alternatively or additionally, the layer composite 10 may have a textile layer 26 which is arranged on a side of the cover layer 16 which faces away from the visible side 24 or the decorative layer 22, the textile layer 26 being connected, for example, to the cover layer 16. The textile layer 26 is formed from polyester, for example.

[0031] In FIG. 1, a joining element 28 is also shown which is formed, for example, from a plastic. As will be described in more detail below, the joining element 28 is connected by means of friction welding to one of the cover layers 14 and 16 and in the present case to the cover layer 16, such that the joining element 28 is a plastic welded part. In other words, the joining element 28 is welded onto the layer composite 10 without this resulting in undesired damage to the layer composite 10.

[0032] During friction welding, the joining element 28 is pressed onto the layer composite 10, in particular the cover layer 16, and is caused to vibrate, as a result of which energy is supplied. The amount of energy supplied must be high enough for the plastic of the joining element 28 and optionally the plastic of the cover layer 16 to melt and for the joining element 28 to be connected to the layer composite 10, i.e., the cover layer 16, at a contact surface. The amount of energy supplied is made up of a normal force with which the joining element 28 is pressed against the layer composite 10 during friction welding, and the frequency and amplitude of the vibration. The amplitude is also referred to as welding amplitude, wherein the frequency is referred to as the welding frequency. In FIG. 2, the normal force is referred to with a force arrow F. Furthermore, double arrows 30 in FIG. 2 illustrate the welding amplitude and/or the welding frequency. An increase in the normal force and an increase in the frequency and/or the amplitude of the vibration lead to an increase in the amount of energy supplied.

[0033] In the case of sandwich composite components, especially sandwich composite components having a thermoplastic foam core, there is generally the risk that too high a normal force during friction welding will damage the layer composite 10. If the input or supplied energy is too high, the cover layer 16 may be melted. As a result, the joining element 28 can penetrate the layer composite 10 in an uncontrolled manner and damage it. This failure pattern can also materialize as a result of a counterforce which acts on the layer composite 10 and opposes the normal force being too low and the loaded core layer 12 collapsing. A further failure pattern is undesired marks resulting on the visible side 24. Such a mark is to be understood, for example, to be an undesired shine or undesired deformation on the visible side 24 and in particular on the surface of the decorative layer 22, wherein such a mark can also be caused by excessive normal force.

[0034] However, the connection of the joining element 28 to the layer composite 10 by friction welding is desirable, since the joining element 28 can be connected to the layer composite 10 in this way in a particularly time- and cost-effective manner, such that a cost-effective production of the vehicle can be achieved overall.

[0035] In order to connect the joining element 28 to the layer composite 10 by means of friction welding and thereby avoid undesired damage to the layer composite 10, provision is made, for example, as shown in FIG. 2, for the core layer 12 to have a higher density in at least one partial region 32 than in second partial regions 34 which are adjacent to the first partial region 32, wherein the joining element 28 is connected to the cover layer 16 in the first partial region 32 by means of friction welding. This higher density in the first partial region 32 compared to the respective second partial region 34 is produced, for example, by pressing the layer composite 10, in particular the core layer 12, more strongly in the first partial region 32 than in the second partial regions 34 during the previously described pressing. As a result of this locally stronger pressing, the core layer 12 has a higher density in the first partial region 32 than in the second partial regions 34, such that the core layer 12 has an increased compressive rigidity and compressive strength in the first partial region 32 compared to the second partial regions 34. The risk of the core layer 12 collapsing during friction welding can thus be kept particularly low. The necessary rigidity/counterforce of the foam can be generated not only by a local pressing of the foam layer, but also by a full-surface pressing. For this purpose, a density increase of the foam takes place over the entire component thickness. It has been proven to be expedient, for example, to press a foam core or core layer 12 with an original thickness of 3 mm and a density of 65 kg/m.sup.3 to approx. 2 mm. This stronger cross-component pressing also helps to consolidate the cover layers.

[0036] As an alternative or in addition to the locally stronger pressing, it is conceivable, for example, to produce the core layer 12 by means of an extrusion method and to vary the extrusion method in such a way that the core layer 12 has a higher density in the first partial region 32 than in the second partial regions 34. Furthermore, it is conceivable to separate one part from the core layer 12, after its production, in the first partial region 32, as a result of which a recess is formed in the first partial region 32. A foam body is then inserted into this recess, the foam body then being arranged in the first partial region 32. Here, the foam body has a higher density than the second partial regions 34. The joining element 28 is preferably produced by injection molding, i.e., as an injection-molded component, such that the joining element 28 can be produced in a particularly time- and cost-effective manner.

[0037] As a result of the locally stronger or higher pressing of the layer composite 10 which is shown on the left-hand side in relation to the image plane of FIG. 2, a counterpressure of the material of the core layer 12, the counterpressure opposing the normal force, can be increased since the core layer 12 has a higher compressive strength and compressive rigidity in the first partial region 32 compared to the second partial regions 34. The increase in the mechanical pressure properties of the thermoplastic foam core is due to the fact that pressing takes place, for example, in the hot state during the production of the component. In this case, the foam core is heated at least almost to the melting temperature of the thermoplastic matrix of the cover layers 14 and 16. At this temperature, which is, for example, 160 degrees Celsius to 250 degrees Celsius, the PET foam core can be compressed without cell walls of the foam core breaking or melting. The thus plastically compressed foam structure can absorb higher forces by the material compression, as a result of which the pressure properties are increased locally. This allows friction welding at a fairly high normal force, which is represented by the length of the force arrow F.

[0038] On the right-hand side of FIG. 2, a further option to avoid undesired damage to the layer composite 10 during friction welding is illustrated. The energy to be input for melting respective bonding surfaces with only a very low normal force is achieved by increasing the welding amplitude and/or welding frequency. Here, the welding amplitude is preferably at least substantially 1 millimeter. By increasing the welding amplitude and/or welding frequency, the normal force can be kept low such that the risk of the layer composite 10 collapsing can be kept particularly low.