DE10156875A1 - Three-dimensional reinforcement structure for fiber-plastic composites and process for their production from a flat structure - Google Patents

Abstract

Three-dimensional reinforcement structures for fiber-plastic composites formed from single-layer or multi-layer oriented fibers or fiber sheets have punctiform and / or linear stiffeners arranged in the area of draping zones for determining draping fixed points and / or draping surfaces as well as boundary lines and / or edge lengths of the 3-D -Free-form surface of the reinforcement structure on (Fig. 2).

Description

The invention relates to reinforcement structures for Fiber-plastic composite materials according to the preamble of claim 1. The invention also relates to a method for producing such reinforcing structures for fiber-plastic composites.

For the production of components from fiber-plastic composite materials (FKV) are usually reinforced flat or thick-dimensional textile reinforcement structures (fabrics, scrims, etc.) are used. The Production of three-dimensional shapes or geometries takes place through a reshaping process associated with a draping process. Often this is a stacked structure made up of several Layers of individual textile fabrics. Both when drying Textile structures as well as pre-impregnated systems (e.g. thermoplastic Plate semi-finished products or prepregs) Semi-finished product or the warehouse structure and limitations of formable geometries (Breuer, UP. "Contribution to forming technology fabric-reinforced thermoplastics "VDI Progress Reports Series 2, No. 433, Düsseldorf VDI publishing house 1997).

The reason for this is the textile architecture, which has drapability determined.

For continuous fiber reinforced plastics are used for reinforcement different types of textile fabrics are used. This is in the Rule around flat fabric semi-finished products and various types of fabrics. The Drapability of such textiles is determined by various process Parameters (fabric type, type of weave of the scrim) of the textile process affects and applies to the entire area shown. In individual Processes, such as the knitting technology (production of multiaxial fabrics) it is only one-dimensional, the drapability influencing parameters (e.g. number and type of weld lines) during the surface production and thus the surface locally to give different drapeability. For fabrics this is Drapability dictated by the choice of fabric type.

Due to the characteristics and properties of the textile fabrics the following processing and mechanical Properties of fiber-plastic composites are determined. The The reinforcement fibers can be tied via the cross points of the Fabric or a mesh shape can be done in scrims. Likewise are Possible adhesive technology. In the stacked fibrous Reinforcement structure are sliding or deformation specifications in the Usually specified over the entire textile area, the other Processing process for fiber-plastic composite influence.

A net-shape production of 3D-shaped components is therefore only under Consideration or knowledge of the exact draping properties of the Semi-finished products possible. The waste-optimized production of 2D individual parts for 3D moldings are therefore only possible to a limited extent. Hochdrapierfähige Semi-finished products such as scrims with jersey binding achieve this Drapability by means of the thread quantity or thread reserve used the mesh structure that binds the reinforcement scrim. This stitch-forming process of knitting for the production of multi-axial scrims takes place only in the axis perpendicular to the knitting unit (DE 196 24 912 A1 and DE 197 26 831 A1 and Hörsting K. + Huster M "Targetting cost reduction by FEA-designed reinforcement textiles "; Proceedings" ECCM-8 ", Naples / June 1998, pp. 635-643). The additional thread introduced works in usually as a disruptive element in the fiber-plastic composite structure. This can be seen, for example, in the lowering of the in-plane properties or in achievable surface qualities. For fabrics, the Draping over the shear of the thread sheets in the Crossing points.

The invention is based on the object, a Reinforcement structure for generic fiber-plastic composites create that defines draping zones on the one hand and the Draping areas adjacent to other areas of the Fiber reinforcement structure leaves untouched, thereby reducing the specific properties of the Optimal use of fibers.

This task is for generic reinforcement structures for Fiber-plastic composite materials in the area of draping zones arranged punctiform and / or linear stiffeners for Determination of draping fixed points and / or draping areas, as well as of Boundary lines and / or edge lengths of the reinforcement structure solved.

Through the precise definition of draping zones, draping areas or Drapier fixed points, sliding or deformation zones on the still flat Cut the dry, packet-like reinforcement structure on the one hand true to size, d. H. 2D semi-finished products for precise final contours Production of 3D free-form surfaces and, on the other hand, targeted forming of such a layer structure possible.

According to a further proposal of the invention, the Stiffening of seams formed as single stitches or linear or can be flat.

The freely programmable seams at the same time several aspects for the production of components from fiber-plastic Composite material optimized. Line-specific corresponding to the component geometry or flat contour seams enable a precise position Cutting out the semi-finished reinforcement and a very simplified Workpiece assembly. By the fiber orientations in the layer structure adjusted variation of both the number of seams and the Sewing direction can optimally use the in-plane fiber properties become. For forming processes is through the described generation of sliding planes, etc. a reduction in wrinkling possible, what the quality and properties of the component made of fiber Plastic composite materials (resin-rich zones, fiber undulations, Fiber shifts). They can also be used for impregnation decisive flow paths between individual fiber bundles through the Adjustment of the fiber packing density can be improved.

Freely programmable sewing heads on the plane allow exact Introduction of fixed points, straight lines or fixed surfaces, which at a Forming leave parts of the reinforcement structure unaffected and release other than draping zones. Ideally, the drape pattern directly into the deposited fiber coulters without additional textiles Process step introduced. Due to the minimal disturbance of the levels Fibers, d. H. there are no weaving patterns or additional ones Knitting threads available, the utilization of the reinforcing fiber Properties can be further increased. On zones that have not set an ideal combination of fibers and matrix is possible. The fibers can be fixed during the impregnation via a minimal number of seams. Through the seams penetrate the entire reinforcement structure, an intermediate layer Avoiding postponement. Undesired wrinkles occur through the Characteristic of the flat one-dimensional semi-finished products not on or can be limited to specific areas.

For certain applications, it is advantageous if the stiffeners of single or multi-layer reinforcement fiber packages made of fabrics, Laid, knitted, knitted or other flat structures and / or prefabricated textile reinforcement structures, for example preforms consist.

To achieve the further object on which the invention is based, a Process for the production of three-dimensional reinforcement structures to create, before draping the reinforcement structure in their Processing in the area of draping zones selective and / or line-shaped stiffeners to form draping fixed points and / or Draping areas, as well as boundary lines and / or edge lengths of the Reinforcement structure introduced.

The stiffening can be done by freely programmable seams are formed, the elasticity of which is varied by using the coming thread material and / or by changing the Sewing parameters such as stitch length and thread tension can be changed can.

If a multi-layer semi-finished package as part of a one-dimensional Forming is to be deformed, it is advisable the sewing parameters of a respective lower layer package compared to the sewing parameters of one to make the top layer package so different, that the thread length introduced into the layer package to be stretched more larger than that in the less stretchable layer package Thread length is.

Further advantages of the invention result from the following Description of an embodiment shown in the drawings.

Show it:

Fig. 1 A 3D free-form surface for a case shell with draping zones and draping planes for the exact definition of edge lengths and unaffected fiber areas;

Fig. 2 A flat semifinished product with stiffeners formed by seams to form draping zones and draping planes for several components for suitcase half-shells;

Fig. 3 shows a blank of a reinforcing fiber structure of a component for a suitcase half-shell;

Figure 4 is a stack of semi-finished products obtained with by varying the sewing parameters and different yarn lengths different drape.

In Fig. 1, a reinforcing structure for a suitcase half-shell is shown, the stacked or laid fibrous flocks of oriented single plies 1 Fabric 1 is formed. The fiber shares 1 can be arranged at any angle, for example at an angle of +/- 45 °. Stiffeners formed by seams 2 are introduced into the reinforcement structure and are used to fix the contour of the reinforcement structure of the case shell. The shape of these seams 2 therefore corresponds exactly in the area of the draping zones to the required contours of the case half shell and the draping conditions. In the deformed state of the reinforcement structure, the seams 2 define boundary lines 3 or edge lengths 4 of the 3D free-form surface of the case shell.

FIG. 2 shows a partial area of a flat web of a reinforcing structure, into which the stiffening seams 2 are introduced. In FIG. 2, therefore, the developments 5 of the 3D free-form surfaces for a total of 6 suitcase half-shells can be seen, in which the seams 2 in the area of the draping zones form the boundary lines 3 and the edge lengths 4 of the 3D free-form surfaces of the suitcase half-shells.

The seams 2 are introduced into the unwindings 5 of the reinforcement structures in the flat state with the aid of programmable sewing heads, the fiber sheets 1 being placed in a predetermined orientation by means of a laying unit and brought into the stitch formation area by sewing heads which can be moved in the X and Y directions.

Subsequently, the individual blanks 6 are cut out of the reinforcement structure web and processed further, for example in accordance with DE 10 00 5 202 A1, into the fiber-plastic composite material.

The elasticity of the seams to be brought in can different sewing parameters can be set. This is done through customization of the thread material used and / or in the semi-finished product introduced thread length.

In FIG. 4 the situation is shown a one-dimensional forming process at a location formed from two packs 7 or 8 Semi-finished package. In the forming process, the upper layer package 7 is stretched more than the lower layer package 8 . Accordingly, when inserting a seam 9 into the upper layer package 7, the stitch length and also the length of the thread to be inserted into the layer package 7 are to be chosen larger than is necessary for the seam 10 to be introduced into the lower layer package 8 .

Claims (6)

1. Three-dimensional reinforcement structures for fiber-plastic composites made from fibers or fiber sheets laid by one or more layers oriented by at least one layer in at least one plane, characterized by punctiform and / or linear stiffeners arranged in the area of draping zones for determining draping fixed points and / or draping surfaces, and of boundary lines and / or edge lengths of the reinforcement structure. 2. Reinforcement structure for fiber-plastic composites after Claim 1, characterized in that the stiffening of seams are formed. 3. Reinforcement structure for fiber-plastic composites after Claim 1, characterized in that the stiffeners of one or multi-layer reinforcing fiber packages made of fabrics, scrims, Knitted, knitted or other fabrics and / or prefabricated textile reinforcement structures, for example preforms. 4. Process for the production of three-dimensional reinforcement structure for fiber-plastic composites made of at least one level or multi-layer oriented fibers or fiber sheets, characterized, that before draping the reinforcement structure in its development in Area of draping zones punctiform and / or linear stiffeners for the formation of draping fixed points and / or draping areas, as well as of Boundary lines and / or edge lengths of the reinforcement structure be introduced. 5. The method according to claim 4, characterized in that the Stiffeners can be formed by freely programmable seams. 6. The method according to claim 5 for the production of at least two stacked layers of existing semi-finished products, characterized in that the sewing parameters of a respective lower layer package compared to the Sewing parameters of an upper layer package in this way can be set differently that the one-dimensional deformation of the Layer packs that are incorporated into the more stretchable layer pack Thread length greater than that in the less stretchable layer package introduced thread length is.