3-DIMENSIONAL HIGH-STRENGTH FIBER COMPOSITE COMPONENT AND METHOD FOR PRODUCING SAME

Abstract

A 3-dimensional high-strength fiber composite component having isotropic fiber distribution, comprising 25 to 70 wt % of high-strength, high-modulus fibers, up to 5 wt % of binding fibers, and 25 to 70 wt % of thermosetting or thermoplastic matrix. The invention further relates to a method for producing same, comprising the following steps: preparing the fibers by opening the fibers by releasing the fibers from fiber bundles, bales, or textile structures; sucking and/or blowing the opened fibers onto a three-dimensional, air-permeable tool half having the contour of this side of the component in an interactively controlled manner; pre-solidifying the obtained fiber molding in the flock box; transferring the fiber molding onto a pressing tool in the form of the contour of the air-permeable tool half of the component; bringing into contact with at least one liquid plastic; and solidifying the fiber molding by pressing in order to form a component.

Claims

1. A method for producing a three-dimensional high-strength fiber composite component with an isotropic fiber distribution with a charge-dependent material distribution made of stiff high-modulus fibers and a plastic matrix, comprising the following steps in the given order: (a)m opening fibers by releasing the same from fiber bundles, bales or textile structures; (b) mixing of the fibers after the opening with at least one binding fiber, wherein the mass proportion of the binding fibers in the entire fiber mass after the mixing is between about 0 and about 5% by weight; (c) sucking and/or blowing of the opened released fibers onto a three-dimensional air-permeable half mold with the contour of this side of the component; (d) solidifying preliminarily the fiber preform in the flockbox; (e) transferring the fiber preform to a pressing mold in the form of the contour of the air-permeable half mold of the component; (f) contacting with at least one liquid plastic material; and (g) solidifying the fiber preform by pressing into a component.

2. The method according to claim 1, characterized in that glass fibers or carbon fibers are employed as said stiff high-modulus fibers.

3. The method according to claim 1, characterized in that the fibers are arranged on the surface of said three-dimensional air-permeable mold during the sucking and/or blowing in such a way that the coverage of the fibers has a uniform weight per unit area over the entire surface.

4. The method according to claim 1, characterized in that the fibers are arranged on the surface of said three-dimensional air-permeable mold during the sucking and/or blowing in such a way that the coverage of the fibers has locally different weights per unit area.

5. The method according to claim 1, characterized in that binding fibers are activated by heated air for preliminarily solidifying the fiber preform.

6. The method according to claim 1, characterized in that the transfer of said fiber preform to a pressing mold is effected by means of a transport tray, in which the fiber preform is retained by a vacuum.

7. The method according to claim 1, characterized in that the uniaxial fiber bundles and/or fabrics are applied to one or both surfaces of the fiber preform.

8. The method according to claim 1, characterized in that one-component fibers of thermoplastic PUR, copolyamide or copolyester is employed as said binding fibers.

9. The method according to claim 1, characterized in that bicomponent fibers with shell materials of thermoplastic PUR, copolyamide or copolyester are employed as said binding fibers.

10. The method according to claim 1, characterized in that resins that are liquid in the application state and made of one of the materials epoxy resin, polyurethane resin, polyester resin or casting polyamide are employed as matrix materials.

11. The method according to claim 1, characterized in that said resin is sprayed on one or both sides of said fiber preform.

12. The method according to claim 1, charachterized in that said resin is injected through nozzles on the mold side into the pressed fiber preform in the closed mold.

13. A three-dimensional high-strength fiber composite component with an isotropic fiber distribution, prepared according to claim 1, comprising from 25 to 70% by weight of high-strength, high-modulus fibers, up to 5% by weight of binding fiber material, and from 25 to 70% by weight of thermoset or thermoplastic matrix.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention is illustrated and described herein with reference to the various drawings, in which like reference numbers denote like method steps and/or system components, respectively, and in which:

[0036] FIG. 1 is an illustration of schematic of the basic principle of the method of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0037] The invention is based on the knowledge that, by the controlled blowing and/or sucking of released fibers, with or without binding fibers, into a three-dimensional air-permeable mold, it is possible to provide a fiber preform in which the fibers are arranged on a three-dimensional molded part in such a way that they are almost isotropic in the longitudinal and transverse directions of the mold, and the fiber preform has a uniform, or deliberately locally non-uniform, weight per unit area. The contour of the air-permeable mold essentially corresponds to the contour of the upper or lower side of the component.

[0038] In a first embodiment, the present invention relates to a method for producing a three-dimensional fiber composite component with an isotropic fiber distribution with a charge-dependent material distribution made of stiff high-modulus fibers and a plastic matrix in very short cycle times, comprising the following steps in the given order: [0039] fiber preparation 1, 2, 3 by opening the fibers by releasing the same from fiber bundles, bales or textile structures; [0040] interactively controlled sucking and/or blowing 6 of the opened released fibers onto a three-dimensional air-permeable half mold 5 with the contour of this side of the component; [0041] preliminarily solidifying the fiber preform in the flockbox 4; [0042] transferring the fiber preform 7 to a pressing mold 11 in the form of the contour of the air-permeable half mold 5 of the component; [0043] contacting 10 with at least one liquid plastic material; [0044] solidifying the fiber preform by pressing 11 into a component.

[0045] By the combination of these steps, a three-dimensional component with an isotropic fiber distribution and partially different weight per unit area can be prepared with almost complete avoidance of defects in the fiber structure, and with a very short cycle time. The productivity is significantly improved thereby as compared to known methods.

[0046] As said fibers, high strength or high-modulus fibers, especially glass fibers or carbon fibers, are employed; however, natural fibers, plastic fibers or other inorganic fibers may be additionally used.

[0047] It is possible to use both sorted fibers and fiber mixtures of fibers with similar or clearly different melting points.

[0048] In another embodiment, the fibers are mixed with at least one binding fiber after the opening. The “opening of the fibers” means the releasing of the fibers from fiber bundles, bales or other textile structures (fiber preparation).

[0049] According to a first alternative, the mass proportion of the binding fibers, based on the total fiber mass, after the mixing may be, for example, 5% by weight or less than 5% by weight. In this case, the binding fibers merely serve for preliminary solidification. For example, co-polyethylene, co-polyester, co-polyamide or thermoplastic polyurethane (PUR) may be used as the material for the binding fibers. Preferably, binding fibers compatible with the plastic matrix are used.

[0050] The introducing of the fibers by blowing/sucking into the mold can be effected in such a way that the fibers have a uniform weight per unit area over the entire surface of the mold.

[0051] However, it is also advantageously possible to distribute the fibers during the sucking and/or blowing on a surface of the three-dimensional, air-permeable mold part in such a way that the fibers have locally differing weights per unit area with respect to the surface. Thus, partially reinforced three-dimensional fiber components can be prepared.

[0052] Binding fibers to which heated air is applied may also be used for the preliminary solidification of the fiber preform. Other possibilities of preliminary solidification include, for example, liquid binders or needle-bonding with air.

[0053] A fiber preform solidified in this way can be transported and later placed onto a pressing mold without falling apart.

[0054] In another embodiment, the preliminarily solidified fiber preform that essentially corresponds to the shape of the component can then be applied by means of a transport tray for transfer to a pressing mold.

[0055] Further, it is conceivable that uniaxial fiber bundles and/or fabrics are introduced along on at least one surface of the fiber preform when the fiber preform is transferred to the pressing mold. This serves for a charge-dependent reinforcement of the component.

[0056] For liquid plastic materials, such as resins (epoxy resin, phenol resin, polyester resin) or casting polyamide (which requires working under an inert atmosphere), the known methods, such as RTM or TRTM, can be applied.

[0057] In another embodiment, it is possible to contact, especially to spray, the fiber preform with a liquid plastic material. PUR resin is particularly important in this context. The further processing may then be effected in an autoclaving or pressing method.

[0058] The preparation of components with a thermoplastic matrix is preferably effected by the use of a fiber mixture of high melting or non-melting fibers, a binding fiber and the matrix fiber. Higher strength thermoplastic materials, such as polypropylene, different polyamides, polyesters, polyetheretherketone, are applied as matrix fibers. The mass proportion of the plastic fibers (matrix) in the entire fiber mass after the mixing is about 30% by weight to 90% by weight.

[0059] For the further processing, the fiber preform is heated and preliminarily solidified at a temperature above the melting temperature of the binding fibers. In another step, it is heated at a temperature above the temperature of the matrix plastic and pressed in a cold pressing mold.

EXAMPLE

[0060] In the following, a preferred embodiment of the invention is described with reference to the drawing, wherein FIG. 1 schematically illustrates the basic principle of the method according to the invention for preparing a three-dimensional fiber component using the HMP III fiber flocking technology.

[0061] The carbon fiber bales were opened, released and mixed with commercially available 3% by weight PUR bicomponent fibers made of a thermoplastic PUR material core and a thermoplastic copolyurethane shell (1, 2, 3). The melting temperature of the copolyurethane was about 100° C.

[0062] In the flockbox 4, there was a closed circulation in the direction of the arrow of cold (room temperature) air.

[0063] The released fiber mixture was weighed and introduced 6 into the air flow.

[0064] The fibers collected in the filter 5, which essentially had the contour of one side of the component. Regions with different open areas sucked different amounts of material, which resulted in different weights per unit area in the component. Using hot air with a temperature above the melting temperature of the shell material of the bico fibers (in this case 100° C.), the fiber preform was solidified to such an extent that it could be transported.

[0065] The fiber preform was removed by means of a removing tray 7 and robot 8, wherein it was retained on the tray by means of a vacuum, and placed in a deposit tray 9 for spraying, sprayed with a second robot 10, and transported into a pressing mold 11, and subsequently pressed and thus solidified.

[0066] In another embodiment, the spraying could also be done directly in the pressing mold 11.

[0067] A suitable conventional pressing mold could be used as said pressing mold 11.

[0068] The thus prepared three-dimensional component had a partially increased weight per unit area in desired regions, and thus different force absorptions and deformation behaviors as desired.

LIST OF REFERENCE SYMBOLS

[0069] 1-3: Fiber processing

[0070] 4: Flockbox

[0071] 5: Filter

[0072] 6: Air flow

[0073] 7: Fiber preform

[0074] 8: Robot

[0075] 9: Deposit tray

[0076] 10: Spraying robot

[0077] 11: Pressing mold