DE10251581B4 - Process for producing textile preforms from textile semi-finished products - Google Patents

Abstract

A textile pre product comprising fibers or rovings (13,14) is placed on a supporting tool (9) with the contours of the preform to be produced. Fibers may be placed in two or three dimensions and after the placing stage, the fibers, which are not yet fully fixed in position, are oriented into preferred directions by a forming and draping stage (12).

Description

The The invention relates to a process for producing textile preforms (Preforms) from semi-finished textile products (precursors), wherein the preforms in particular for the Production of fiber reinforced Plastics are provided, preferably using a matrix system soaked with an adhesive resin and under elevated temperature as well possibly increased Pressure to be cured.

at the production of fiber reinforced Plastics come different textile precursors, in the following also called semi-finished products, for use. In addition to fabrics and braids can use nonwovens and other textile fabrics be used. Subsequently can these semi-finished products in different processing processes and combined and connected with each other. The resulting Preforms (so-called preforms) are finally made with a matrix system soaked and mostly under elevated Pressure and elevated Temperature cured.

today are textile precursors such. Tissue and braids in the end the manufacturing process applied in or on an intermediate carrier. at Braided may be e.g. to act around cylindrical bodies, around these these circulatory web-shaped be wound up. The geometry of these carriers is not used for or Forming of the semi-finished products, but only as an aid to transport and for storage.

in the During the further manufacturing process, the semi-finished products of the subcarrier body again removed, assembled and then by reorientation and Forming of the fiber structure into the desired shape (so-called preform) brought. Here are some fiber orientations through the manufacturing process fixed and can later no longer be influenced. For this reason, certain component geometries with semi-finished products that were previously applied to intermediate carriers, not more, though the actual manufacturing process is this geometry enable would.

In Use are also continuous processes in which the precursor directly after the surface formation process the further manufacturing process is supplied. The possible reorientation and Forming of the textile semifinished product, however, happens without the upstream surface forming process is actively focused on.

A The exception is the braiding of cores, the cores of a desired Geometry from the outside be braided to a desired To achieve fiber orientation. The cores used can afterwards be removed. However, the use of cores only allows certain geometries of the precursors. In addition, the core geometry and their dimensions limited. Another exception are so-called round or spiral fabrics, in which the length individual thread systems (e.g., warp threads) is made variable, causing a change of direction of the semifinished product in the plane is achieved.

The Fixation of precursors can be done with the help of a binder. The binder systems used are mainly thermoplastic Substances which are e.g. in powder form applied the semi-finished and activated under the influence of temperature become. In addition to a determination of the fiber orientation, the Binder systems are used to compact the preforms Condition to fix.

at The braiding technique can be the two-dimensional and three-dimensional Lichens are differentiated. The three-dimensional braiding makes it possible To create semi-finished products with a defined cross-sectional geometry, that too during changed the manufacturing process can be. By independent guidance of the individual threads of the mesh can e.g. L- or U-shaped Cross sections of the precursors are generated. The resulting fiber structure are near-net shape and have a moderate drape behavior. The two-dimensional braiding is realized in so-called round braiding machines. The resulting semi-finished product is a tubular structure, in which no fibers with an orientation in the radial direction (90 ° to the surface of the Hose) can be introduced.

Two-dimensional Braids are easy to drape and can be used as flat or tubular semi-finished products be further processed. During the Braiding process it is possible fiber orientations defined by braiding core geometries and To achieve semi-finished product geometries. By introducing stretched Fibers (so-called standing threads) in the withdrawal direction, the drapability in some spatial directions reduced.

In DE 198 09 264 A1 describes a fiber-laying arrangement for a preform of a fiber composite component having at least one gel layer of rectified juxtaposed, each made of reinforcing fibers fiber bundles and at least one layer of a sheet-like melt adhesive structure, wherein the layers lie on each other and are sewn together. In an associated In a method of making a preform for a fiber composite component, the fiber mesh assembly is formed, heated, compression molded, cooled, and demolded.

In DE 1 090 166 C is a reinforcing material for castings, consisting of a carrier fabric, preferably in one direction extending carrier threads and reinforcing threads, such as glass fibers, which are fixed on the carrier fabric by adhesive, is described. The reinforcing threads, which are strong in relation to the threads of the base fabric, are free of adhesive except at the joints and are closely spaced but do not adhere to each other.

In DE 42 14 636 A1 a reinforcing structure is described, which is very adaptable, because its carrier layer is cut to size and the applied reinforcing threads are freely selectable in their dimensioning and laying. By using cords as reinforcing threads, the laying can be significantly simplified. In addition, the inventive assignment of carrier layer and reinforcing threads by embroidering, which allows great variability.

The Basics of textile fabrics will influence Planck, H., " and exploiting the properties of the sheet on component properties ", man-made fibers / textile industry (Industrial Textiles), May 1991, 41./93. Jg., P. T141-T147.

One Disadvantage of the cited prior art is that several process steps for the production of preforms (preforms) textile semi-finished products are necessary.

Of the The invention is based on the object, a manufacturing process specify the type mentioned, with a smaller number of procedural steps.

The The object is achieved in that the textile semi-finished products each on a support with a later preforms appropriate contour or adapted geometry are applied, and that at the end of a fibrous two- or three-dimensional Textile process the not yet finally fixed fibers of the textile Semi-finished by a forming and Drapiervorgang in a desired orientation to be brought.

One An essential advantage of the invention is that the semi-finished products not only on intermediate carrier be applied, but on a support, which is a later component or preform adapted contour. There is an interaction i.e. a correlation between the surface forming process and the Forming or Drapierprozeß possible, so that e.g. the different take-off lengths of standing threads when Forming into a disc considered can be. By reshaping and draping are advantageously still sliding Fibers in a desired Orientation brought. Unlike braiding around nuclei are others with the method according to the invention Fiber orientations and geometries possible. The dimensions of the preforms and their geometry are much less limited. For example, can be cylindrical preforms with in the withdrawal direction over 360 ° circulating Fibers are made.

It is thus advantageously possible omit the intermediate step of applying the semifinished product to an intermediate carrier. In the method according to the invention become surface formation process and forming process connected so that geometries are realized can, with the conventional ones Manufacturing processes are not possible. The inventive method takes advantage of the condition that at the end of the fibrous two- or Three-dimensional textile process, the fibers are not yet finally fixed are. By reshaping and draping are still at this point slidable fibers are brought into a desired orientation. This orientation may e.g. by a geometry adapted subcarrier will be realized. The elimination of the intermediate step has the advantage that damage and ondulation of the fibers can be reduced by manipulations.

• I. Ziehen durch ein oder entlang eines Umformwerkzeugs (Matrize), das den Querschnitt und z. T. auch die Faserorientierung verändert (z.B. ermöglicht eine gekrümmte Matrize das Drapieren der Stehfäden im Flechtschlauch).
• II. Wickeln auf ein Umformwerkzeug (Matrize), das den Querschnitt und z.T. auch die Faserorientierung verändert.
• III. Pressen oder Drücken in oder entlang eines Umformwerkzeuges (Matrize), das den Querschnitt und z.T. auch die Faserorientierung verändert.

Embodiments of the invention are described in the subclaims 2 to 9. This takes into account that even during braiding the fibers can be pre-oriented by appropriate forming aids and guides. The forming and draping process directly following the textile production process can be realized by different methods and tools. Conceivable, for example:

• I. pulling through or along a forming tool (die), the cross-section and z. T. also changes the fiber orientation (eg allows a curved die draping the standing threads in Flechtschlauch).
• II. Winding on a forming tool (die), which changes the cross section and in some cases also the fiber orientation.
• III. Pressing or pressing in or along a forming tool (die), which changes the cross section and in some cases the fiber orientation.

In addition to reshaping and draping can the semi-finished are compacted simultaneously.

• a) Fixierung durch die Fasern selbst: Durch die Reibung, die die Fasern gegeneinander haben, wird ein Verrutschen verhindert.
• b) Fixierung durch Binder: Durch Einbringen eines Binders vor, während oder nach dem Umform- bzw. Drapierungsvorganges werden die Fasern fixiert.
• c) Fixieren durch Matrixmaterial: Vor, während oder nach dem Umform- bzw. Drapierungsvorganges wird der Matrixwerkstoff in die Fasern eingebracht und
• d) teilweise oder vollständig gehärtet oder die Viskosität des Harzes herabgesetzt. Dieses ermöglicht die Fixierung der Fasern.

The fixation of the fibers can be done after the forming and draping over the fibers themselves, a binder or a matrix system:

• a) Fixation by the fibers themselves: Due to the friction that the fibers have against each other, slipping is prevented.
• b) Fixation by binder: By introducing a binder before, during or after the forming or Drapierungsvorganges the fibers are fixed.
• c) Fixing by matrix material: Before, during or after the forming or Drapierungsvorganges the matrix material is introduced into the fibers and
• d) partially or completely cured or reduced the viscosity of the resin. This allows the fixation of the fibers.

• a) Textile Herstellungsverfahren für zweidimensionale Gebilde (z.B. 2D-Weben, Wirken, Stricken, 2D-Flechten, Vliesstoffe) oder
• b) Textile Herstellungsverfahren für dreidimensionale Gebilde (z.B. 3D-Weben, Abstandsgewirke, Stricken, 3D-Flechten).

In principle, many different textile production processes are conceivable for the process according to the invention, for example:

• a) Textile production processes for two-dimensional structures (eg 2D weaving, knitting, knitting, 2D braiding, nonwovens) or
• b) Textile manufacturing processes for three-dimensional structures (eg 3D weaving, knitted fabrics, knitting, 3D braiding).

In The drawing is an embodiment after of the invention, and shows:

1 a block diagram for a sequence of a method according to the invention and

2a and 2 B an apparatus for performing the method according to 1 in front and side view.

In 1 To explain the general concept using the example of a braiding process the following process steps in the form of blocks for producing a textile preform from a semi-finished textile product (precursor) are shown in the drawing: braiding process 1 for a loose and drapable braid 2 ; possible order 3 a binder on the pre-mesh, eg pulverulent binder; Forming or draping process 4 of the precontour 2 ; Fix 5 of the precontour 2 to a semi-finished textile product; apply 6 of the textile semifinished product on a support and subsequent processing 7 of the semifinished product into a textile preform, which is intended for the production of a fiber-reinforced plastic article. Between the braid process 1 ie the surface formation process 1 , and the forming or draping process 4 an interaction can take place, which through the connecting line 8th is clarified.

From 2a and 2 B apparent principle device, in addition to other device examples are possible, shows a rotating carrier and forming tool 9 which is a drum 10 with one side of the drum 10 attached boundary plate 11 whose diameter is greater than the diameter of the drum 10 goes. On the drum 10 is the loose, drapable and possibly provided with a binder order Vorgeflecht 2 hung up, taking the drum 10 at the same time as the fixed storage of the pre-braid 2 as well as for the transport of the formed semi-finished product. How out 2 B can be seen, additional non-forming and pressing rollers 12 be provided for the semi-finished, which are optionally also equipped with a heating or cooling device for the binder. Again 2 B can also be seen, standing threads, ie stretched fibers of the same length 13 on the circumference of the drum 10 be arranged while standing threads with variable length 14 on the protruding annular surface of the limiting disc 11 issue.

A similar Principle is also applied to the weaving technique, in which the length of individual Thread systems (e.g., warp threads) is made variable. Thus, a change of direction in the plane of the textile surface achieved. Such a technique is used for so-called round or spiral fabrics applied. However, this change of direction happens exclusively in one level. The new concept would go through Forming and draping right after the weaving process also a three-dimensional Allow semi-finished product geometry.

1

braiding

2

Vorgeflecht

3

binder application

4

forming or Drapiervorgang

5

Fix of the pre-netting

6

apply of the textile semifinished product

7

processing of the semifinished product

8th

connecting line for interaction

9

Carrier and forming tool

10

drum

11

handguard

12

forming and pressure rollers

13

Stehfäden same length

14

Stehfäden with variable length

Claims (9)

Process for producing textile preforms (preforms) from textile semi-finished products (precursors), wherein the preforms in particular for the manufacture ment of fiber-reinforced plastics, which are preferably impregnated using a matrix system with an adhesive resin and cured under elevated temperature and optionally elevated pressure, characterized in that the textile semi-finished products each on a support ( 9 ) are applied with a contour or adapted geometry corresponding to the later preforms, and that at the end of a fiber-arranged two- or three-dimensional textile process ( 1 ) the not yet finally fixed fibers ( 14 ) of the semi-finished textile products by a forming and draping process ( 4 ) are brought into a desired orientation. Method according to claim 1, characterized in that the unfixed fibers ( 14 ) by pulling through or along a forming tool that alters the cross-section and in part also the orientation of the fibers ( 9 ). Method according to claim 2, characterized in that as forming tool ( 9 ) a curved die for draping defined, in the process incoming semi-finished products, which also contain standing threads can be used in a semi-finished textile product. A method according to claim 1, characterized in that the unfixed fibers by winding or depositing on a cross-section of the textile semi-finished product and partly also the orientation of the fibers changing forming tool ( 9 ). A method according to claim 1, characterized in that the unfixed fibers by pressing or pressing in or along a cross-section of the semi-finished textile product and partly also the orientation of the fibers changing forming tool ( 9 ). Method according to claim 4 or 5, characterized by the use of a die as forming tool ( 9 ). Method according to one of claims 1, 2, 3, 4, 5 or 6, characterized characterized in that the fibers prevent slipping by the Friction of the fibers are fixed against each other. Method according to one of claims 1, 2, 3, 4, 5 or 6, characterized in that the fibers by introducing a binder before, during or after a forming or Drapierungsvorgang ( 4 ) are fixed. Method according to one of claims 1, 2, 3, 4, 5 or 6, characterized in that the fibers by introduction and partial or complete curing of the matrix material before, during or after a forming or Drapierungsvorgang ( 4 ) are fixed.