Method for producing a fiber-reinforced plastic outer skin component for a vehicle, and fiber-reinforced plastic outer skin component

Abstract

A method for producing a fiber-reinforced plastic outer skin component for a vehicle includes the following steps: a) providing a semifinished fiber product which includes at least one fiber layer with predetermined fiber orientation; b) applying an uncured plastic matrix in the form of an epoxy resin-based or polyurethane-based matrix system to the semifinished fiber product; c) placing the semifinished fiber product provided with plastic matrix into a mold; and d) pressing the semifinished fiber product in the mold in order to shape and cure the semifinished fiber product to form a fiber-reinforced plastic component. A shrinkage-reducing additive in the form of filler particles is admixed with the uncured plastic matrix and the uncured plastic matrix is applied to the surface of the semifinished fiber product that in the finished component faces the visible side of the component.

Claims

1. A fiber-reinforced plastics outer-paneling component for a motor vehicle, comprising: a fiber reinforcement which comprises at least one fiber ply with a predetermined fiber orientation; a plastics matrix which is applied to the fiber reinforcement; wherein the plastics matrix is an epoxy-resin matrix or a polyurethane matrix; and shrinkage-reducing filler particles disposed in the plastics matrix, wherein a size of the shrinkage-reducing filler particles is at most 0.1 millimeters and wherein the shrinkage-reducing filler particles are particles of spodumene and/or fumed silicon dioxide; wherein a first portion of the plastics matrix that does not contain the shrinkage-reducing filler particles is applied directly to a side of the fiber reinforcement that faces toward a visible side of the fiber-reinforced plastics outer-paneling component and wherein a second portion of the plastics matrix that contains the shrinkage-reducing filler particles is applied to the first portion of the plastics matrix.

2. The fiber-reinforced plastics outer-paneling component according to claim 1, wherein the at least one fiber ply is comprised of continuous fibers.

3. The fiber-reinforced plastics outer-paneling component according to claim 1, wherein the fiber reinforcement comprises carbon fibers.

4. The fiber-reinforced plastics outer-paneling component according to claim 1, wherein the fiber reinforcement is visible on the visible side of the fiber-reinforced plastics outer-paneling component through the plastics matrix.

5. A method for production of a fiber-reinforced plastics outer-paneling component for a vehicle, comprising the acts of: a) providing a semifinished fiber product which comprises at least one fiber ply with a predetermined fiber orientation; b) applying an uncured plastics matrix in a form of an epoxy-resin-based or polyurethane-based matrix system to the semifinished fiber product, wherein a shrinkage-reducing addition in a form of filler particles is added to the uncured plastics matrix; c) inserting the semifinished fiber product with the uncured plastics matrix into a mold; and d) pressing of the semifinished fiber product in the mold for shaping and for hardening to produce the fiber-reinforced plastics outer-paneling component; wherein the uncured plastics matrix is applied to a surface of the semifinished fiber product that faces toward a visible side of the fiber-reinforced plastics outer-paneling component; wherein in act b) a first portion of the uncured plastics matrix that does not contain the shrinkage-reducing addition is first applied directly to the semifinished fiber product followed by applying a second portion of the uncured plastics matrix that contains the shrinkage-reducing addition to the first portion; wherein the shrinkage-reducing filler particles reduce shrinkage during hardening of the plastics matrix in the mold, wherein a size of the shrinkage-reducing filler particles is at most 0.1 millimeters and a concentration of the shrinkage-reducing filler materials in the plastics matrix when uncured is at most 40% by weight, and wherein the shrinkage-reducing filler particles are particles of spodumene and/or fumed silicon dioxide; wherein the first portion of the uncured plastics matrix that does not contain the shrinkage-reducing filler particles is applied to the surface of the semifinished fiber product that faces toward the visible side of the fiber-reinforced plastics outer-paneling component.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a diagram of the significant steps of a process of the invention;

(2) FIG. 2A is a sectional view, after step B in a first version of the process, of a semifinished fiber product to which matrix material has been applied;

(3) FIG. 2B is a sectional view, after step B in a second version of the process, of a semifinished fiber product to which matrix material has been applied; and

(4) FIG. 3 is a sectional view of a fiber-reinforced plastics outer-paneling component.

DETAILED DESCRIPTION OF THE DRAWINGS

(5) FIG. 1 is a diagram of the significant steps of a process of the invention for the production of a fiber-reinforced plastics component for the example of a CRP roof with optical properties suitable for visible components, where A indicates step a), B indicates step b), C indicates step c), D indicates step d) and E indicates step e).

(6) In step a), a semifinished fiber product 10 is provided. The semifinished fiber product 10 is formed by at least one fiber ply of reinforcement fibers. It is preferable that the semifinished fiber product 10 is configured by mutually superposing a plurality of fiber plies in the form of stack; by way of example, FIG. 1 depicts 4 fiber plies 11 to 14 in the form of stack. At least one of the fiber plies has a predetermined fiber orientation, as is the case by way of example in laid scrims, woven fabrics or braided fabrics. Different fiber plies can be combined with one another in the stack. Equally, individual fiber plies can be configured as fibrous nonwoven web. The nature of the fibers is not in principle subject to any restriction. However, it is preferable that the semifinished fiber product comprises one or more fiber plies comprising continuous carbon fibers.

(7) The semifinished fiber product 10 can by way of example take the form of cut-to-size product with outline already replicating the general shape of the required component.

(8) In step b), an uncured plastics matrix 20 is applied to the semifinished fiber product 10. An epoxy-resin based matrix system or a polyurethane-based matrix system is used as plastics matrix.

(9) In order to reduce shrinkage arising during hardening, an addition 30 in the form of filler particles is added to the plastics matrix 20 of the invention. If the required component is intended to be a component with optical properties suitable for visible components, the filler particles are selected from the group of talc, spodumene and fumed silicon dioxide. The size of the particles is preferably at most 0.1 mm, their concentration in the uncured plastics matrix being at most 40% by weight.

(10) The plastics matrix 20 comprising the shrinking-reducing addition 30 is applied to a large area of the semifinished fiber product 10, e.g., via a robot-guided applicator 40. The material can be applied directly to the semifinished fiber product 10; FIG. 2A provides relevant detail. Alternatively, the plastics matrix 20 can be applied in a two-stage process. FIG. 2B provides relevant detail.

(11) After step b), the semifinished fiber product 10 comprising the plastics matrix 20 and comprising the shrinkage-reducing addition 30 is inserted into a mold 50 in step c). The mold has two mold halves 51 and 52 which when closed enclose a cavity that in essence has the shape of the required fiber-reinforced plastic component. The mold 50 can be closed by way of an actuator that is not depicted. The actuator can by way of example be configured as press. When the mold 50 is closed (step d), the semifinished fiber product 10 is forced into the shape of the cavity, after which it is compressed. The closing pressure distributes the plastics matrix 20 in the cavity, and the matrix is also further forced here into the interstices between the fibers.

(12) The mold 50 is heated in order to harden the plastics matrix 20; for this purpose, by way of example, heating tubes 53 are provided. After hardening, the fiber-reinforced plastics component 60 can be removed from the mold 50, depicted in step e), and can optionally then be introduced into further operations.

(13) FIGS. 2A and 2B serve to provide detail of two alternative versions of a process in step b). Each of FIGS. 2A and 2B is a diagrammatic sectional depiction of the semifinished fiber product 10, showing only two fiber plies 11 and 12 of the stack. The respective fiber plies are configured as woven fabric comprising a large number of carbon fiber bundles; (fiber bundles 100, 101, 102 are designated merely by way of example). The fiber ply 11 is intended to be the first fiber ply in the finished component (view from the visible side of the component), and to be visible through the plastics matrix.

(14) In FIG. 2A, a shrinkage-reducing addition 30 as described above is added to the plastics matrix 20, and the plastics matrix 20, with the addition 30, is applied directly to the uppermost fiber ply 11 of the semifinished fiber product 10. During subsequent compression in the mold, the plastics matrix 20 is forced between the fibers or fiber strands, and infiltrates the interstices. The solid particles 31, 32 (for reasons of clarity only two particles are provided with reference signs) of the shrinkage-reducing addition 30 migrate only to some extent between the fibers or fiber bundles 100, 101, 102, and to some extent are retained at the upper side of the semifinished fiber product 10, and are deposited thereon. This advantageously leads to an increased proportion of shrinkage-reducing particles specifically at the surface of the semifinished fiber product 10, where the intention is to avoid shrinkage during hardening.

(15) FIG. 2B is a sectional depiction of the fiber plies 11 and 12 of the semifinished fiber product 10 after the plastics matrix 20 has been applied in an alternative version of the process in a two-stage step b). A first portion of the plastics matrix 20 without shrinkage-reducing addition 30 was first applied to the upper side of the semifinished fiber product 10, i.e., directly to the uppermost or first fiber ply 11. In a second application, the second portion of the plastics matrix 20 with added shrinkage-reducing addition 30 is then applied on top of the previously applied plastics matrix 20. This two-layer application brings about better infiltration of the fiber interstices by plastics matrix 20 during subsequent compression in the mold.

(16) In both versions of the process, shrinkage-reducing particles 31, 32, which reduce shrinkage during hardening, remain on the upper side of the semifinished fiber product 10 or on the uppermost fiber ply 11; this in principle improves surface quality, and it is moreover possible to increase the mold temperature to temperatures at which it was not hitherto possible to achieve acceptable surface quality. It is thus possible to achieve a large reduction of residence time in the mold 50 and to reduce the total production time of the component 60 in an easy and inexpensive manner.

(17) FIG. 3 is a diagrammatic sectional view of the fiber-reinforced plastics outer-paneling component 60 after hardening. The fiber reinforcement 10 has been embedded into the hardened plastics matrix 20A. The hardened plastics matrix 20A comprises the shrinkage-reducing addition 30; filler particles 31, 32 are arranged here at least on that side of the fiber reinforcement 10 that faces toward the visible side 61, i.e., on the uppermost fiber ply 11.

(18) The embodiments are not to scale, and are not restrictive. Modifications are possible within the scope of activity of a person of ordinary skill in the art.

LIST OF REFERENCE CHARACTERS

(19) A, B, C, D, E Process steps 10 Semifinished fiber product 11 to 14 Fiber plies 100, 101, 102 Fiber strands 20 Uncured plastics matrix 20A Hardened plastics matrix 30 Shrinkage-reducing addition 31, 32 Filler particle 40 Applicator 50 Mold 51, 52 Mold halves 53 Heating tubes 60 Fiber-reinforced plastics component 61 Visible side

(20) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.