Arcuate fiber composite plastic preform and method for production of curved profiles

Abstract

An arcuate fiber composite plastic preform and a method for the production of curved profiles with any fiber layer structure are disclosed, which include a layered fiber structure with a base and an arcuate outer contour, an inner edge and an outer edge. The fiber layer structure is configured with a first inner area provided with elevations and depressions, a second adjacent central area with no elevations and depressions and a third outer area and provided with radially oriented open recesses. The method of producing curved profiles from fiber composite plastic preforms having any fiber layer structure includes a molding step, whereby the outer area of the preform with wedge-shaped recesses is being compressed while the inner relief-shaped area is being completely stretched thereby flattening the relief.

Claims

1. An arcuate fiber composite plastic preform for the production of curved profiles comprising, a fiber layer structure forming a plane or curved base with an arcuate outer contour bordered by front ends, an inner edge with a curvature facing a center of a curve and an outer edge with a curvature facing away from the curve, said fiber layer structure configured with, a first inner area, starting from the inner edge, with a surface including a relief structure along an extent of the curve with elevations and depressions vertical to the base, a second area starting from the first inner area and extending outward to an adjacent central area as a base and void of elevations and depressions, and a third outer area starting from the base extending outward and adjacent the outer edge, said outer edge provided with radially oriented open recesses.

2. The arcuate fiber composite plastic preform of claim 1, wherein the first inner area is coordinated relative to a target curved profile such that the area with the relief structure incorporates a surface that corresponds exactly to an extended surface in the curved profile after the relief structure of the inner area has been stretched and thus flattened.

3. The arcuate fiber composite plastic preform of claim 1, wherein the relief structure is configured with elevations and depressions in a wavy pattern.

4. The arcuate fiber composite plastic preform of claim 1, wherein the recesses along the outer edge are arranged in regularly distanced intervals.

5. The arcuate fiber composite plastic preform of claim 1, wherein the recesses are wedge-shaped.

6. The arcuate fiber composite plastic preform of claim 1, wherein the preform is constructed of a number of fiber layers, each layer including unidirectional fiber segments with a fiber angle =0, or a fiber angle 0.

7. A method for the production of a curved profile of fiber composite plastic from the arcuate fiber composite plastic preform according to claim 1 comprising the steps of: providing a mold having a plane or curved contact surface in the shape of an arch with an outer edge of a radius and a arch length and an inner curved edge of a radius smaller than the outer edge and an arch length smaller than the inner curved edge, wherein each, the inner and outer edge of the contact surface is followed by an oblique or downwardly oriented vertical cheek surface, where an outer cheek surface is curved convexly at the outer edge and an inner cheek surface at the inner edge is concavely curved, placing the fiber composite plastic-preform such that the base area as deck area is positioned flush with the contact surface of the mold, wherein the adjacent areas, which are the inner area with a relief structure acting as a stretching area, and the outer area, with wedge-shaped recesses acting as a compression area, protrude beyond the cover surface of the mold; engaging the outer protruding compression area of the preform with the outer cheek surface of the mold, such that the wedge-shaped recesses of the compression area are closed and engaging the inner protruding stretching area of the preform with the inner cheek surface of the mold, wherein the inner relief-shaped stretching area is being completely stretched and thus flattened; wherein engaging the cheek surfaces is carried out in either one step at once or in subsequent steps in any order.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which:

(2) FIG. 1 is a FVK preform for the production of curved profiles from fiber composite material plastic (FVK) with profile-directed fiber coordinating system according to the present invention;

(3) FIG. 2 is a schematic illustration of a FVK preform for the production of curved profiles from fiber composite plastic (FVK) in a polar coordinate system;

(4) FIG. 3 is a schematic illustration of a three-dimensional curved profile from fiber composite plastic (FVK) having an exemplified target geometry after forming, and

(5) FIG. 4 is a schematic illustration of a layer structure of a three-dimensional curved profile.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(6) Throughout all the Figures, same or corresponding elements are generally indicated by same reference numerals.

(7) Turning now to the drawing, and in particular to FIG. 1, there is shown an arcuate FVK-preform 1 for the production of curved profiles from fiber composite plastic FVK with a profile-directed fiber coordinate system. A profile-directed fiber coordinate system means that the abscissa of the fiber coordinate system is oriented parallel to the tangent of the profile line, in the shown example the curvature of the arcuate preform 1, and the ordinate extends correspondingly vertical, that is, 90 thereto, with both located in the base area 2.

(8) Thus, the arcuate preform 1 exhibits a variable fiber layer structure, forming a base 2 with an arcuate outer contour. The base 2 can be either level or arched. For example, the base 2 can be arched like a cone surface section.

(9) The arcuate outer contour has a front end each, 3a and 3b as well as an inner edge 4 facing the center of the curve and an outer edge 5 facing away from the center of the curve. The preform 1 includes three different areas. A first inner area 6 starting from the inner edge 4 wherein the surface of the inner area 6, along the extension of the curve has a wavy relief structure 7 with elevations 7a and/or depressions 7b and vertical to base 2. Starting from the first inner area 6 and outwardly adjacent, there is a second central area shown as base area 8 without elevations and depressions and vertical to basis area 2. The base area 8 of preform 1 in the shown example is essentially configured two-dimensional, that is, it corresponds to a level base 2. The base area 8 can also be arched like the sector of a cone surface. Starting from the base area 8 outwardly adjacent and extending to the outer edge is a third outer area 9 which is provided with wedge-shaped radially oriented recesses 10 that are open toward the edge 5. The wedge shaped recesses 10 are preferably distanced from each other in even intervals.

(10) Alternative to the illustration in a profile-directed fiber coordinate system, the arcuate FVK preform 1 can be shown in a polar coordinate system as seen in FIG. 2. The definition of local fiber angle is dependent from the position of each viewing point P in the polar fiber coordinate system, which itself is defined by a polar angle and a radius r. A fiber angle of =0 thus corresponds to the tangential direction at each point P, a 90 fiber angle corresponds at point P of the radial direction to point P of the polar coordinate system. All further fiber orientations are derived from that. The description model of the polar fiber coordinate system is applicable at least locally, whereby it is not necessary to apply the same polar coordinate system for the entire arcuate fiber structure, for example, in case there are cracks in the curve of the arcuate form.

(11) The arcuate FVK preform 1 includesstarting from the inner edge 4 which corresponds to a radius r in the polar coordinate systema first inner area 6, whose surface exhibits a wavy relief structure along the course of the curve of the FVK preform 1 with elevations 7a and/or depressions 7b relative to base 2, in the shown example, relative to the plane of the polar coordinate system. A central area 8 adjacent the first inner area 6, is essentially configured two-dimensional. In the outer area 9, adjacent to the base area 8, the preform 1 has wedge-shaped radially oriented recesses 10 with their openings oriented toward the outer edge 5. The outer edge 5 itself, aside from the recesses 10, has a radius r.sub.2.

(12) FIG. 3 shows a three-dimensional curved profile 11 from fiber composite plastic (FVK) with an exemplified target geometry, which is realized through molding of the arcuate FVK preform 1 shown in FIG. 1. The molding is carried out through a process to produce a curved profile from fiber composite plastic (FVK) by using an arcuate FVK preform 1 as shown in FIG. 1 and FIG. 2 and a mold, not shown here. The mold has a curved surface in the shape of a level curve having an outer edge with a larger radius and a greater arch length and an inner curved edge with a smaller radius and smaller arch length. At each of these two edges of the curved surface of the mold follows a downward oriented curved cheek surface, wherein the outer cheek surface at the outer edge is curved convexly and the inner cheek surface at the inner edge is curved concavely.

(13) The method for the production of a curved profile from fiber composite plastic (FVK) according to FIG. 3 includes the following successive method steps:

(14) a) positioning a deck area 12 (See FIG. 3) that corresponds to the base area 8 of the arcuate FVK preform 1 as shown in FIG. 1 and located between the inner area 6 with the relief structure 7 and the outer area 9 with the wedge-shaped recesses 10, on the curved contact surface of the mold that is shaped as a level arch.

(15) b) engaging a stretching area 13 of the FVK preform 1 which corresponds to the inner area 6 with the relief structure 7, with the inner cheek surface of the mold thereby forming an edge 14 between the deck area 12 and the stretching area 13 at an inner edge of the mold, and engaging a compression area 15, which corresponds to an outer area 9 with the wedge-shaped radial recesses 10 with the outer cheek surface of the mold resulting in edge 16 between the deck area 12 and the compression area 15, wherein the contacting at each of the cheek surfaces of the mold takes place in either one step or in several steps in any order.

(16) Thereby, a three-dimensional curved profile 11 is realized, which essentially has an upside down U-shaped cross section.

(17) FIG. 4 refers to a schematic illustration of a layered structure of a three-dimensional curved profile 11 after molding the arcuate FVK preform 1. An advantage of the present invention is that the FVK preform 1 having a variable fiber layer structure can be realized without technological constraints and thus allows an optimal exploitation of the structural properties of fiber composite material. The three-dimensional curved profile 11, as shown in FIG. 4 in schematic representation can be realized with fiber layers from unidirectional fiber segments 17 with a fiber angle =0, as well as with fiber layers from unidirectional fiber segments 18 with a fiber angle 0. In FIG. 4, the different yet unidirectional fiber layers are schematically illustrated. The definitions for fiber angle are relative to a profile-directed fiber coordinate system.

(18) While the invention has been illustrated and described as embodied in composite fiber preform according to a coordinate system, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. The embodiments were chosen and described in order to best explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.