Multilayered Woven Fabric as well as Corresponding Production Method

Abstract

The invention relates to a woven fabric of warp and weft threads with a construction in warp thread direction of at least first, second and third warp threads (11, 13, 12) running above one another, wherein: the third warp threads (12) always extend between the first and second warp threads (11, 13), the weft threads (16) are guided through alternating loom sheds (35, 36, 37, 38) between as well as below and above these at least three warp threads (11, 13, 12), and the third warp threads (12) consist of a different material than the first and the second warp threads (11, 13). Similarly the invention relates to a method for producing a multilayered woven fabric of warp and weft threads by means of a weaving machine.

Description

The invention relates to a multilayered woven fabric of warp and weft threads as well as a method for the production of such a multilayered woven fabric.

Multilayered woven fabrics are known in great variety in the most different embodiments and the most distinct purposes.

The U.S. Pat. No. 1,802,907 A discloses a weaving method with weaving heddles, which comprise pairs of heddle eyes that are elongated in the vertical direction and are arranged in alignment for loose ground warp threads, whereby respectively between two of such pairs, a heddle eye of small height is provided in the middle or center of the heddle for a pile warp. With heddles embodied in this manner, the necessary number thereof for the shed formation can be significantly reduced, because fewer adjacently arranged heddles are necessary. Also, interfering friction between warp threads can be avoided. The heddles disclosed in the U.S. Pat. No. 1,802,907 A are especially suitable for use for the double plush weaving.

It is the object of the present invention to provide a multifariously applicable and robust woven fabric of several layers or plies, especially for the production of a shaped structural component, and a corresponding production method.

This object is achieved by a woven fabric of warp and weft threads with a construction in the warp thread direction of at least first, second and third warp threads that run over one another, wherein:

• • the third warp threads always extend between the first and second warp threads,
  • the weft threads are guided through alternating sheds between as well as below and above these at least three warp threads, and
  • the third warp threads consist of a different material than the first and second warp threads.

Through the multilayered or multi-ply construction with different materials, especially with third warp threads lying between the first and second warp threads, the most varied woven fabric constructions with correspondingly different characteristics and fields of application are realizable. For example, the first and second warp threads can have physical characteristics very different from the third warp threads, such as for example different mechanical characteristics with respect to e.g. tearing or breaking strength, different thermal behavior, different chemical resistance, etc. Through a corresponding selection of the materials, the multilayered woven fabric can be utilized for the most varied or different applications.

Especially preferably, the third warp threads contain a high performance material, for example carbon or glass. Carbon and glass fibers are usually embedded in a synthetic plastic matrix, so that the third warp threads in this case consist of a composite material. Carbon fibers are characterized by an extreme strength and stiffness with simultaneous low weight. Particularly, the woven fabric according to the invention can be given a very high tensile strength through the use of carbon. Herein the warp threads containing a high performance material or consisting of a high performance material are also referred to as reinforcement threads.

It is particularly advantageous if the third warp threads are embodied as tapes or rovings. Tapes are spread thread collections of essentially parallel-extending threads that are adhesively bonded with one another, whereby the tapes comprise a greater width than height. Tapes are thus robust and economical surfacial patterns for especially technical applications. A bundle, cord or multi-filament yarn of parallel arranged filaments (endless fibers) is designated as a roving, which is predominantly used in the production of fiber composite plastics or fiber reinforced plastics (FRP). The cross section of a roving is usually elliptical or rectangular. Most commonly filaments of glass, aramid or carbon are grouped together as rovings. Through the use of the abovementioned thread geometries, it is possible to produce especially woven fabrics that can be utilized in multifarious manners e.g. in lightweight construction, for example in the motor vehicle field or in aircraft construction.

Preferably the first and/or the second warp threads contain at least one thermoplastic material. In an especially advantageous embodiment, the first and/or the second warp threads consist completely of at least one thermoplastic material. Through thermal influence, especially through heating of the woven fabric according to the invention, the thermoplastic material can be melted, whereby the molten material then preferably permeates between the fibers of the high performance material.

Especially in combination with third warp threads of a high performance material lying internally in the woven fabric, by means of the invention, a woven fabric can be realized, which on the one hand has excellent formability, and on the other hand comprises a very high tensile strength due to the internally-lying third warp threads.

The woven fabric according to the invention can, for example, be utilized where until now layups of unidirectional oriented (UD) reinforcement fibers have been utilized. In comparison to the UD layups, which are utilized in the prior art, when using the woven fabric according to the invention an advantage arises in the adaptation or fitting of this woven fabric with unidirectional oriented reinforcement fibers to the form or shape of a finished end-use structural component. The reinforcement fibers, considered by themselves, form a UD layup. Through the woven fabric structure, in which the reinforcement fibers are embedded as the third warp threads, it is prevented that these reinforcement fibers become shifted in an undesired manner during the draping or fitting to prescribed shapes. The reinforcement fibers are held in position by the surrounding warp and weft threads. If this is desired, the entire woven fabric structure can be thermally fixed after the draping or fitting to a final end shape. In this option, the surrounding first and second warp and weft threads are produced of a thermoplastic material.

Accordingly, the invention also makes possible the production of a formable or reformable woven fabric, because the plastic matrix of the first and/or second warp threads again becomes soft with a larger heat application. Thus, woven fabrics according to the invention can be formed or shaped to any desired new geometries by hot forming tools. Woven fabrics according to the invention are also well recyclable, because the carbon or glass fibers can be easily separated from the plastic matrix by heating. Thus, through the invention there is achieved a further development of composite materials such as for example CFP (carbon fiber reinforced plastic), which consists of carbon fibers embedded or potted in a liquid plastic matrix (usually thermosetting plastics).

It contributes to a good handleability when the materials of the first and second warp threads are the same. When the woven fabric according to the invention is, for example, heated from both sides of the woven fabric, then the same heating temperatures can be used. With a symmetrical layer construction of the woven fabric, for example outer first and second warp threads of the same material, same geometry and same thickness as well as internally-lying third warp threads, a woven fabric with well predictable shape and mechanical characteristics can be realized in a relatively simple manner.

It is especially preferred if the first and second warp threads are embodied as tapes. This especially applies to the case that the third warp threads are similarly embodied as tapes. According to a preferred embodiment, the multilayered woven fabric consists exclusively of tapes. Especially preferably, binding threads for holding together the woven fabric are not utilized.

Preferably at least some, especially preferably all, of the weft threads contain at least one thermoplastic material. Furthermore it is preferred if the weft threads consist entirely of at least one thermoplastic material. Thereby the weft threads can similarly be a part of the thermoplastic matrix that covers the third warp threads. In this manner, the third warp threads can be completely covered by thermoplastic material at least completely from above and from below, namely if the first and second warp threads as well as the weft threads all consist of one or more thermoplastic materials.

The at least one thermoplastic material is preferably selected from the group that encompasses the following materials, among others: olefin homo- or copolymers, for example polyethylene (PE) or polypropylene (PP), polyamide (PA), polyurethane (PU), or other thermoplastic materials. Among these are included e.g. acrylonitrile butadiene styrene (ABS), polylactate (PLA), polymethylmethacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polystyrene (PS), polyetheretherketone (PEEK) and polyvinyl chloride (PVC).

Especially preferably, the first, second and third warp threads and preferably also the weft threads comprise such a width and are woven into the woven fabric in such a manner so that the third warp threads are completely covered from below and above by the first and second warp threads as well as the weft threads. In this case, all areas of the third warp threads are covered. In the case of thermoplastic first and second warp threads as well as weft threads on the one hand, and third warp threads of a high performance material on the other hand, a closed formed part can be realized (by heating the woven fabric, reforming and cooling), in which all of the high performance fibers are enclosed. Only thermoplastic material is visible from both sides of the woven fabric.

According to a correspondingly advantageous embodiment, the first and second warp threads are at least exactly as wide as the third warp threads. Hereby the first and second warp threads cover, preferably completely, the third warp threads in the top plan view and in the bottom plan view. Thereby, the abovementioned encapsulation of the third warp threads can be realized in a simple manner.

According to an advantageous embodiment, additionally to the first, second and third warp threads, at least fourth—that is to say if applicable also fifth and if applicable also sixth, etc.—warp threads are present, which are arranged in the woven fabric always between the first and second warp threads and always in the same consistent position with respect to the third warp threads, that is to say always either above or below these third warp threads.

As mentioned above, the first and/or the second warp threads preferably form the outermost woven fabric structures, and the third warp threads preferably form the internally-lying woven fabric structure of a woven fabric constructed with three layers. However, without further complexity, woven fabrics with more than three layers are also possible. For example, if the first warp threads form a layer A, the second warp threads form a layer B, and the third warp threads form a layer C, or third, fourth and fifth warp threads form layers C, C′, C″, etc., then for example the following layer constructions are possible: A-C-C′-B, A-C-C′-C″-B. In this regard, the layers A and B can consist of warp threads of the same quality or characteristic with respect to the material, especially a thermoplastic material, and geometry. It is also possible that the third, fourth, etc. warp threads C, C′, etc. consist of the same or of different high performance materials or respectively contain such. In further embodiments, for example, the third and fifth warp threads C contain a high performance material and fourth warp threads contain a thermoplastic material.

Thus, the invention especially makes possible a woven fabric with third warp threads of a composite material (for example carbon fibers or glass fibers, etc., saturated or impregnated in plastic or coated with plastic) in the form of rovings or tapes, and furthermore first and second warp threads of thermoplastic tapes (PET, PP, PA etc.). In this regard, the composite material is preferably completely covered from above and below by thermoplastic material in the form of at least the first and second warp threads as well as the weft threads. The mass ratio or the volume ratio of the first and second warp threads as well as of the weft threads to the third warp threads in this regard is preferably uniform or the same over the entire surface area and is exactly definable through the selection of the thickness of the utilized thermoplastic tapes. The third warp threads that are worked-in are integrated in a mechanically stable manner into the surrounding woven fabric structures and can thus—as far as the interlacing or binding construction of the woven fabric permits it—be draped, that is to say applied on curved surfaces. For adapting or fitting onto the contour, the semi-finished parts are stretched and pulled to be warped, whereby the drapeability thereof changes depending on the weave type and the stitching type of the woven fabric. In this manner, fiber composite materials and so-called prepregs can be produced. In a thermal consolidation, the woven fabric can be transformed into a form-stable surfacial shaped article through melting of the outwardly-lying thermoplastic tapes.

The invention similarly encompasses a method for the production of a multilayered woven fabric of warp and weft threads, especially a woven fabric as described above. The method according to the invention encompasses the following steps:

• • a plurality of warp thread bundles that extend next to one another in the weft thread direction and that at least consist of first, second and third warp threads that respectively extend over one another, are supplied to a shedding arrangement,
  • in its weaving cycles, the shedding arrangement opens alternating sheds between the respective at least three types of warp threads as well as below and above these, in order to guide weft threads through these sheds,
  • wherein the third warp threads consist of a different material than the first and second warp threads,
  • wherein the first and second warp threads preferably contain a thermoplastic material, while the third warp threads preferably contain of a high performance material, for example carbon or glass.

This method, which is also described in the DE 10 2014 112 468.5, which is not yet published at the time of the filing of this application, and which is hereby referenced for disclosure purposes, is carried out as follows according to a preferred embodiment: In a weaving machine several heddles are arranged next to one another in the weft direction, which is variously known in the prior art. Furthermore, behind at least some of these heddles in the warp direction, respectively one or more heddles are arranged behind one another. Respectively at least one warp thread is guided through each one of the heddles that are thusly arranged respectively one behind another, whereby several warp threads are guided in the warp direction above one another, and thereby respectively form a warp thread stack (a “warp thread stack” is herein defined as an arrangement of several warp threads over one another). During weaving, the heddles arranged respectively in a row behind one another are moved non-synchronously, that is to say alternately, upwards and downwards repeatedly, and are thereby individually positioned in the Z-direction. Thereby, different openings or loom sheds are formed one after another between warp threads that extend above one another, through which weft threads are inserted.

The advantages of this embodiment are especially to be seen in that in addition to the heddles positioned conventionally next to one another, additional heddles are provided, which are arranged in the warp direction, that is to say in the running direction of the warp threads, behind the previously mentioned heddles (which are known from the prior art). Thereby it is possible that several warp threads can be guided above one another. Thereby, in addition to the warp threads that are guided next to one another—which are widely known from the prior art—further warp threads that lie above one another can be inserted into the woven fabric.

Thereby it is preferred if the warp threads extend registered or aligned above one another. The term “registered” herein means that—as seen from above—all warp threads guided above one another of a row of heddles arranged behind or after one another, lie within the width of the widest warp thread, generally a tape. Basically, however, an offset with an only partial registration of two or more warp threads guided above one another is also possible.

Through an alternating up and down motion of three heddles arranged behind one another, these heddles are individually positionable and therewith also the warp threads guided by these heddles. Thereby different openings or loom sheds between the warp threads running above one another are realizable, through which the weft threads can then be inserted. Such openings are functionally comparable with the loom sheds known from the prior art, because in both cases warp threads (in the case according to the invention warp threads lying above one another, and in the known case warp threads lying next to one another) are moved apart from one another in the Z-direction, in order to guide through a weft thread.

Thus, for the production of a woven fabric according to the invention, at least three heddles for respectively one warp thread stack are arranged behind one another, through which at least a total of three warp threads are guided in the warp direction above one another, whereby the heddles, through alternating upward and downward motion, guide the warp threads together and apart, in order to be able to carry out corresponding weft insertions. In this regard, in the weft direction a plurality of such rows of three (or more) heddles arranged behind one another in the warp direction, is provided.

For producing a complex weave pattern, the warp thread stacks present next to one another in the weft direction are moved relative to one another corresponding to the weave pattern to be achieved, so that the loom sheds, which are achieved by the repeated upward and downward movement of the heddles arranged in the warp direction in a row behind or after one another, between the warp threads of the respective warp thread stacks, and the sheds achieved thereby in the weft direction between the warp thread stacks arranged after one another in the weft direction, are matched or adapted to one another, especially preferably with the aid of an electronic machine control.

Each one of the heddles guided behind one another in the warp direction preferably guides respectively one warp thread, that is to say it is embodied and arranged for deflecting it. In other words, thus each one of these heddles is responsible for the upward and downward movement of one single warp thread. In an embodiment that is advantageous in this regard, respectively only one heddle eye for deflecting an associated warp thread is provided in each one of the heddles that is arranged in a row behind one another in the warp direction. Through this embodiment, a precise control of all warp threads is possible.

The height of the heddle eye of a heddle in comparison to the height of the heddle eye of a different heddle arranged therebehind is preferably essentially identical or only slightly different in order to realize the several preferred layers of the warp threads running above one another as described further below. Furthermore it is advantageous if the width of the heddle eyes of heddles arranged behind one another is essentially the same size, wherein this width preferably is adapted to the maximum width of the tapes that are to be woven.

According to an especially preferred embodiment, with heddles arranged behind one another, the respective front heddle, that is to say the one that is respectively located closer to the machine outlet, comprises at least one and—corresponding to the above disclosure—preferably exactly one heddle eye, through th which a first warp thread is guided and deflected. This heddle eye comprises—for the purpose of the stated guidance and deflection in the Z-direction—a smaller height than an elongated or slotted hole with greater height that extends in the Z-direction and that is arranged below or above the stated heddle eye, for the position-fixed or deflection-free passage of at least a second warp thread. In this regard, the term “position-fixed” means that the second warp thread is not significantly moved along with the upwards and downwards movement of the front heddle, but rather remains in its position, and the rods of the heddle that laterally bound the elongated hole are guided along it. For guiding the second warp thread, there is provided a rear heddle that is arranged closer to the machine inlet, and that for this purpose comprises at least one and—corresponding to the above disclosure—preferably exactly one heddle eye with a smaller height for threading through and deflecting the stated second warp thread in the Z-direction. Also this rear heddle comprises an elongated hole that extends in the Z-direction with a greater height than the stated heddle eye of the rear heddle, whereby this elongated hole is then arranged above or below the stated heddle eye. The elongated hole of the rear heddle serves for the position-fixed or deflection-free passage of at least the stated first warp thread.

In this regard, preferably that heddle of which the heddle eye guides the uppermost warp thread of a warp thread stack, comprises an elongated hole below this heddle eye, while that heddle of which the heddle eye guides the lowest warp thread of a warp thread stack comprises an elongated hole above this heddle eye.

For producing a woven fabric according to the invention, in addition to the front and rear heddles (for the first and second warp threads), at least three middle heddles (for the third warp threads) are arranged in the warp direction between the respective stated front and rear heddles. In this regard, the middle heddles preferably respectively guide a third warp thread, for which each middle heddle preferably respectively comprises a corresponding heddle eye for guiding and deflecting such a third warp thread. With several middle heddles advantageously arranged next to one another in the weft direction, these heddles respectively guide a third warp thread, which extends in the Z-direction always between the respective first and second warp threads of the same warp thread stack. Thereby the woven fabrics according to the invention with at least three warp threads guided above one another are possible.

With further middle heddles (namely fourth, fifth, . . . ), the heddles lying further toward the rear (that is to say in the direction of the machine inlet) guide the (fourth, fifth, . . . ) warp threads that are respectively allocated to them in the Z-direction between those warp threads that are guided by the heddles arranged further toward the front (that is to say in the direction of the machine outlet) and further toward the rear. The middle heddles correspondingly comprise preferably respectively one elongated hole above its heddle eye and one elongated hole below its heddle eye.

Because the sequence of the warp threads in respectively one warp thread stack always remains the same, with three warp threads of one warp thread stack running above one another, four different positions can be realized:

• • all three warp threads above the weft insertion plane (the term “weft insertion plane” here is understood to refer to that plane through which the weft threads run during the insertion thereof into the sheds formed by the warp threads arranged next to one another in the weft direction),
  • all three warp threads below the weft insertion plane,
  • one above and two below the weft insertion plane,
  • two above and one below the weft insertion plane.

Generally it pertains that with n warp threads lying above one another, n+1 permitted positions arise. In contrast thereto in the prior art, only binary positions (warp thread above or below the weft insertion plane) are possible.

In contrast to the prior art, at least three warp threads run—as explained above—above one another and form a warp thread stack. While in the prior art each warp thread can only take up an upper and a lower position, with three warp threads running above one another four positions can be realized.

The respective rows or also only sections of these rows of front, middle and rear heddles are preferably respectively arranged in heald frames, so that in this embodiment several heald frames are provided behind one another. Thereby the production and operation are simpler and more economical.

According to an alternative, the weaving machine according to the invention is embodied as a Jacquard weaving machine, wherein the heddles are individually movable through use of a control.

The invention further relates to a method for the processing of a woven fabric of the above described type and/or produced corresponding to the above described method.

Through the woven fabric structure, in which special third warp threads are embedded, it is prevented that these special warp threads, which are e.g. embodied as reinforcement threads with or of a high performance material, are shifted in an undesired manner during a draping process or when fitting to prescribed curved or otherwise embodied three-dimensional structures.

In a further method according to the invention for woven fabric processing, the woven fabric contains preferably first and second warp threads with at least one thermoplastic material as well as weft threads similarly preferably with at least one thermoplastic material, wherein through heating above the melting point of the at least one thermoplastic material, the woven fabric can be fixed in a three-dimensional form or shape. By the penetration of the melted thermoplastic material between the fibers of the at least third warp threads one obtains a stable structure. For this, for example a correspondingly constructed forming tool, which need not be explained further for the skilled artisan, can be utilized.

Finally the invention similarly encompasses a formed or shaped structural component that has been produced with the above described method. Such a formed structural component can, for example, be utilized for exterior skins in the vehicle and aircraft construction field.

In the following the invention will be explained in further detail in connection with drawings. The same reference numbers represent the same or comparable elements. It is shown by:

FIG. 1 a perspective view onto three heddles arranged behind one another as well as schematically illustrated weaving machine elements;

FIG. 2 the three heddles of the FIG. 1 arranged behind one another (schematic illustration);

FIG. 3a-d the three heddles of the FIG. 2 with threaded-in warp threads in four different positions;

FIG. 4a-d the schematic weave binding or interlacing principle of a first woven fabric according to the invention with six exemplary weft threads S1-S6 (FIG. 4a) as well as a top plan view (FIG. 4b) and a view of the rear side (FIG. 4c) of this woven fabric as well as an illustration of the binding-in or interlacing of the third warp threads in this woven fabric (FIG. 4d);

FIG. 4e a cut-out section of a cross-sectional illustration through the woven fabric of the FIGS. 4a-4d;

FIG. 4f a cut-out section of a cross-sectional illustration through a further woven fabric, and

FIG. 5a-d the schematic weave binding or interlacing principle of a second woven fabric according to the invention with six exemplary weft threads S1-S6 (FIG. 5a) as well as a top plan view (FIG. 5b) and a view of the rear side (FIG. 5c) of this woven fabric as well as an illustration of the binding-in or interlacing of the third warp threads into this woven fabric (FIG. 5d).

In FIG. 1, significant elements of a weaving machine according to the invention for weaving tapes are illustrated extremely schematically. At the machine inlet there is a bobbin creel 40 with a plurality of bobbins 41, from which warp threads are drawn off in the warp direction K (indicated by the exemplary reference number 13 with respect to unwinding from a bobbin 40. At the machine outlet, the inserted weft thread 16 in the present example is transported by an oscillating or swinging weaving reed 44 against the finished woven fabric 18, which is thereafter rolled up onto a take-up roll 45. However, arrangements are also known in which the woven fabric 18 is transported to the inserted weft 16.

In the weaving section, three heddles 1, 2, 3 (in the following also abbreviated to heddles 1-3) are illustrated arranged corresponding to the invention behind or after one another in the warp direction K, whereby the front heddle 1 is positioned toward the machine outlet and the rear heddle 3 is positioned toward the machine inlet. For the sake of clarity, the heddles 1-3 are presently represented perspectively; in reality they are oriented perpendicularly to the warp direction K. In this regard, preferably there are several rows of heddles arranged next to one another (not shown), whereby these rows extend into the drawing plane (that is to say in the weft direction S, which is however represented also tilted obliquely in FIG. 1 for the sake of clarity). In this regard, the greatest variety of arrangements of heddle rows can be selected as desired and depending on the weaving task.

For the sake of illustration it is presently sufficient if only one such row of three heddles 1-3 arranged behind one another in warp direction K is illustrated in the FIG. 1.

Each one of the heddles 1-3 comprises respectively one heddle eye 21, 22, 23 (subsequently also abbreviated as heddle eyes 21-23) with a smaller height than respectively two elongated holes 31a, 31b, 32a, 32b, 33a, 33b (subsequently also abbreviated as elongated holes 31a-33b) arranged above and below these heddle eyes, wherein the elongated holes have a longitudinal extension or length that corresponds to a multiple of the height of the individual heddle eyes 21-23. Respectively one warp thread 11, 12, 13 (subsequently also abbreviated as warp threads 11-13) in the form of a tape is threaded through each one of the heddle eyes 21-23. The arrangement of the heddles 1-3 as well as the embodiment of the heddle eyes 21-23 as well as of the elongated holes 31a-33b behind one another necessitates that the warp threads 11-13 extend above or over one another as seen in the top plan view. In this regard, the elongated holes 31a-33b are all embodied equally wide and adapted to the width of the tape-shaped warp threads 11-13, so that these can run flat or planar in the heddle eyes 21-23 without becoming particularly wavy.

Presently, the first warp thread 11 threaded through the heddle eye 21 of the front heddle 1 is the lowest or bottom warp thread (whereby also the opposite sequence is possible without further difficulty, that is to say the front heddle can also be embodied and arranged so that the warp thread guided by it is the uppermost or top one). Then from the bottom to the top, there follow the third warp thread 12 and the second warp thread 13, whereby the uppermost or top (second) warp thread 13 is threaded through the heddle eye 23 of the rearmost heddle 3. Corresponding to the arrangement of the heddles 1-3 successively following one another in the warp direction K, the warp threads 11-13 run from the bottom to the top. In this regard, the position of the heddle eyes 21-23 is selected in such a manner so that the warp threads 11-13 do not extend in the same horizontal plane (and thereby being in the way of each other), but rather so that—with an equally large deflection of the heddles 1-3—a small vertical spacing distance is present between them.

The three heddles arranged one after another in warp direction are once again shown in FIG. 2, but in this illustration respectively rotated by 90° and shown with a spacing distance relative to one another (in reality only the narrow sides of the heddles 1-3 would be visible in this view). From this it can be seen that the three heddle eyes 21-23 are offset in height, so that the three warp threads 11-13 maintain the mentioned vertical spacing from one another, so that it does not give rise to mechanical tensions or too great friction between them. Moreover, in FIG. 2, the warp direction K and the weft direction S are drawn-in, which together define the weft insertion plane SE. The weft direction S extends perpendicularly to the warp direction K, whereby the three heddles 1-3 are arranged behind or after one another in the warp direction K, and usually several rows of heddles arranged behind one another in the weft direction S (that is to say perpendicularly to the drawing plane) are present.

As can be seen in FIG. 1, the warp threads 12, 13 are threaded through the upper elongated hole 31a of the front or forwardmost heddle 1, while the lower elongated hole 31b is empty. The second warp thread 13 runs through the upper elongated hole 32a of the middle heddle 2, while the first warp thread 11 is guided through the lower elongated hole 32b thereof. The two first and second warp threads 11, 12 are guided through the lower elongated hole 33b of the rear heddle 3, while the upper elongated hole 33a is empty.

In FIG. 1 it is illustrated that the two front heddles 1, 2 are moved into a lower position, while the rear heddle 3 are located in an upper position. Upon moving one of the heddles—in FIG. 1 for example the heddle 2 can be moved upwardly or the heddle 3 can be moved downwardly—the warp thread 12 (or 13) moved in the heddle eye 22 (or 23) of this heddle 2 (or 3) is also correspondingly deflected, while the other two warp threads 11, 13 (or 11, 12) are guided through the elongated holes 32a, 32b (or 33a, 33b) of the corresponding heddle 2 (or 3) without being deflected. These warp threads 11, 13 (or 11, 12) not guided through the heddle eye 22 (or 23) of the upwardly or downwardly moved heddle 2 (or 3) thus remain stationary or position-fixed due to the configuration or embodiment of the elongated holes 32a, 32b (or 33a, 33b) of this heddle 2 (or 3), that is to say these warp threads are not deflected. When, for example, the heddle 2 of FIG. 1 is moved upwardly, then only the warp thread 12 is also correspondingly moved upwardly.

In FIGS. 3a-3d (once again—as in FIG. 2—illustrated with heddles rotated by 90°) in accordance with the above disclosure, it is made further clear how, through alternating upwards and downwards motions of the heddles 1-3, openings or loom sheds 35, 36, 37, 38 arise in a warp thread stack, through which then weft threads S can be inserted (perpendicular to the drawing sheet plane). In FIG. 3a, all three heddles 1-3 are shown in a bottom position, so that all three warp threads 11-13, due to the threading into the individual heddle eyes 21-23, run through their respective lowest vertex point. In FIG. 3b, the rear heddle 3 is deflected upwardly, whereby a loom shed 36 opens between the uppermost warp thread 13 threaded through the heddle eye 23 of the heddle 3 and the other warp threads 11, 12, through which a weft thread 16 (not shown) can be inserted. With several warp thread stacks arranged next to one another in the weft direction (encompassing for example respectively three warp threads 11-13, that are respectively guided by three heddles 1-3 arranged behind one another in the warp direction K), and through corresponding actuation of the upwards and downwards movement of all heddles 1-3 arranged in warp and weft direction, the shed formation in the weft thread plane and the loom shed formation according to the invention can be adapted or tuned to one another, in order to obtain a complex woven fabric. The loom shed 35 that is upwardly open in FIG. 3a is also to be understood in this context, because the weft threads, through warp thread stacks (not shown) present therebehind (that is to say perpendicularly to the drawing sheet plane) are similarly guided through loom sheds, in order to obtain the woven fabric binding or interlacing.

In FIG. 3c, additionally also the heddle 2 is lifted upwardly, whereby the warp thread 12 threaded through its heddle eye 22 is correspondingly carried upwardly with it, so that a different loom shed 37 opens between the warp threads 11 and the warp threads 12, 13 for a weft insertion. According to FIG. 3d, all so three heddles 1-3 and therewith all warp threads 11-13 are illustrated in the upper position, whereby—for the illustrated warp thread stack—a downwardly open loom shed 38 results. Thus, in total four different positions are possible by means of the three heddles 1-3. Generally, n+1 positions can be realized when n is the number of the heddles arranged behind one another.

In the next cycle the warp threads 11-13 are moved downwards preferably in the reversed sequence—first lowering the heddle 1, then the heddle 2, then the heddle 3. Therefore a reciprocal “overtaking” of the warp threads 11-13 relative to one another is not possible; their sequence from the top to the bottom always remains the same.

It is of course also possible to simultaneously lift or lower more than one individual one of the heddles 1-3. For example, in the situation illustrated in FIG. 3a, both rear heddles 2, 3 can be lifted simultaneously. Through such a group-wise lifting and lowering of several heddles, the variability of achievable weave patterns can be further increased.

In FIG. 4a, the schematic weave binding or interlacing principle of a woven fabric with six exemplary weft threads S1-S6 is illustrated, while adjacently running warp thread rows are referenced by the letters A-F. This illustration gives—as seen from the top to the bottom—the weft threads S1-S6 lying behind one another in the warp direction (into the illustration plane). Thus, the weft thread S1 is guided through the shed first, thereafter the weft thread S2, etc. Additionally in FIG. 4a, two different warp thread stacks as an example are referenced with the reference number 15. FIG. 4a shows respectively the orientation and position of the individual warp threads 11, 12, 13, which are all embodied as tapes here, with reference to the respective weft thread 16, which is similarly embodied generally as a tape.

FIGS. 4b-d show the weave pattern of the woven fabric 18 corresponding to FIG. 4a, and particularly FIG. 4b shows, a top plan view, FIG. 4c shows a view from the backside, and FIG. 4d shows the binding-in of the third warp threads 12 into the woven fabric 18. In the illustrations of FIGS. 4b-d, all warp threads 11-13 and the weft threads 16 extend in the drawing plane.

In the top plan view of FIG. 4b, always only the lower first warp threads 11 as well as the weft threads 16 are visible. This is in accordance with the above statement that the sequence of the warp threads 11, 12, 13 from the top to the bottom is always the same. Corresponding to that, in the rear view of FIG. 4c, only the upper second warp threads 13 and the weft threads 16 can be recognized. The third warp threads 12 that are not visible in FIGS. 4b and 4c lie either directly below or above the weft threads 16 or between the first and second warp threads 11, 13 (see FIG. 4a). This is once again illustrated in FIG. 4e, whereby in this illustration the warp threads 11, 12, 13 and the weft thread 16 (here S1 of FIG. 4a) are not illustrated tightly woven together, but rather are illustrated in a stylized manner for better clarity of illustration.

In FIG. 4d, the binding-in or interlacing of the third warp threads 12 into the woven fabric 18 with reference to the weft threads 16 is illustrated in a top plan view (the first and second warp threads 11, 13 are not represented).

It is also mentioned that, with the three or also more warp threads 11, 12, 13 guided above one another, the upward and downward motion of the heddles 1, 2, 3 can be controlled in such a manner so that the weft thread 16 is not visible in the finished woven fabric 18, neither from the front side nor from the back side, in at least one weft thread row. In this regard, several of such weft thread rows that do not fix the woven fabric can be present, which are separated from one another by conventional weft thread rows that bind the woven fabric. In this regard, in the cross-sectional illustration of FIG. 4f, it is schematically shown (for only one weave pattern repetition in the weft direction), how, for example with three warp threads 11, 12, 13 running above one another, the weft thread 16 runs between the warp threads 11 and 12 in one warp thread stack and between the warp threads 12 and 13 in the adjacent warp thread stack.

A second possible weave binding or interlacing principle for a woven fabric 18 according to the invention is illustrated in FIGS. 5a-d, wherein the same reference numbers as in the remaining figures have been used. Through a different pattern for the formation of the openings or the loom sheds (see the loom sheds 35-38 in FIG. 3), a different binding or interlacing is obtained, whereby also in the woven fabric 18 of FIG. 5, the third warp threads 12 always extend between the first and second warp threads 11, 13 (see FIGS. 5b, 5c). Once again in a top plan view, FIG. 5d shows the binding-in or interlacing of the third warp threads 12 into the woven fabric 18 in relation to the weft threads 16, whereby the first and second warp threads 11, 13 are not illustrated again here.

The first, second and third warp threads 11, 13, 12 as well as the weft threads in the embodiments illustrated in the figures are especially preferably embodied as tapes or rovings. In this regard, the third warp threads 12 especially contain a high performance material, for example carbon or glass.

The first and the second warp threads 11, 13 as well as advantageously also the weft threads 16 in the embodiments illustrated in the figures especially preferably contain at least one thermoplastic material. Preferably they consist completely of at least one thermoplastic material, for example of an olefin homo- or copolymer, for example polyethylene (PE) or polypropylene (PP), of polyamide (PA), polyurethane (PU), acrylonitrile butadiene styrene (ABS), polylactate (PLA), polymethylmethacrylate (PMMA), polycarbonates (PC), polyethylene terephthalate (PET), polystyrene (PS), polyetheretherketone (PEEK) and/or polyvinyl chloride (PVC).

As can be seen in the figures, presently the first, second and third warp threads 11, 13, 12 as well as the weft threads 16 comprise such a tape width so that the third warp threads 12 are completely covered by the first and second warp threads 11, 13 as well as the weft threads 16. In this regard, the first and second warp threads 11, 13 as well as the weft threads 16 are at least exactly as wide as the third warp threads 12 and completely cover these in the top plan view and in the bottom plan view.

Thus, according to the above disclosure, a woven fabric can be realized, in which thermoplastic tapes in the form of first and second warp threads (or also further warp threads, then further warp threads running in the interior of the woven fabric) cover, from above and below, at least third warp threads in the form of tapes or rovings with a high performance material (preferably a composite material with carbon or glass in a synthetic plastic matrix, e.g. a carbon tape). Preferably by means of the above described method, the individual layers of the tapes forming the first, second and third warp threads are actuated via the heddles and form the respective loom shed (also generally named opening above), into which the weft thread that similarly preferably consists of thermoplastic material is inserted. By the selected binding or interlacing, the composite tape consisting of the third warp threads or the roving (namely the carbon or carbon fibers) can be bound into the thermoplastic woven fabric with more or less flotation. Through the selection of the thickness of the thermoplastic tape (first and second warp threads, weft threads), an exact fiber-matrix ratio can be selected. The resulting non-consolidated textile construction or textile fabric is flexible, whereby the composite components are fixed in their position or orientation by the binding or interlacing of the woven fabric. The woven fabric is drapable as far as the binding or interlacing allows. Through application of pressure with simultaneous heating above the melting point of the selected thermoplastic matrix system, the woven fabric is fixed in the desired form or shape. In this regard, the thermoplastic components melt and the molten material permeates, saturates or impregnates the composite fibers, that is to say for example carbon or glass fibers. Thereby there arises a homogeneous composite structural component, which, after drying and cooling, can be used for construction.

The invention was explained in detail in connection with example embodiments. Combinations, as far as they are technically possible, are similarly encompassed by the invention, just like derivations or modifications within the claims. Also, generally, no limitations are made with respect to the number of the heddles arranged behind one another in the warp direction and the arrangement of the rows arranged in the weft direction, whereby the rows consist of heddles arranged at least partially behind one another. In this regard, also warp threads that do not form the uppermost and lowermost warp threads (the first and second warp threads) of a warp thread stack may contain a thermoplastic material or also a different material as a high performance material.

REFERENCE NUMBER LIST

1 front heddle

2 middle heddle

3 rear heddle

11 first warp thread

12 third warp thread

13 second warp thread

15 warp thread stack

16 weft thread

18 woven fabric

21 heddle eye

22 heddle eye

23 heddle eye

31a elongated hole

31b elongated hole

32a elongated hole

32b elongated hole

33a elongated hole

33b elongated hole

35 loom shed

36 loom shed

37 loom shed

38 loom shed

40 creel

41 bobbins

44 weaving reed

45 take-up roll

K warp direction

S weft direction

SE weft insertion plane

Claims

1. Woven fabric of warp and weft threads with a construction in warp thread direction of at least first, second and third warp threads (11, 13, 12) running above one another, wherein:

the third warp threads (12) always extend between the first and second warp threads (11, 13),

the weft threads (16) are guided through alternating loom sheds (35, 36, 37, 38) between as well as below and above these at least three warp threads (11, 13, 12), and

the third warp threads (12) consist of a different material than the first and second warp threads (11, 13).

2. Woven fabric according to claim 1, characterized in that the third warp threads (12) contain a high performance material, for example carbon or glass, and preferably consist completely of such a high performance material.

3. Woven fabric according to claim 1, characterized in that the third warp threads (12) are embodied as tapes or rovings.

4. Woven fabric according to claim 1, characterized in that the first and/or the second warp threads (11, 13) contain at least one thermoplastic material and preferably consist completely of at least one thermoplastic material.

5. Woven fabric according to claim 1, characterized in that the first and second warp threads (11, 13) are embodied as tapes.

6. Woven fabric according to claim 1, characterized in that at least some, preferably all, weft threads (16) contain at least one thermoplastic material and preferably consist completely of at least one thermoplastic material.

7. Woven fabric according to claim 1, characterized in that at least one of the warp threads and/or at least some of the weft threads contain at least one thermoplastic material that is selected from one or more members of the following group: olefin homo- or copolymers, for example polyethylene (PE) or polypropylene (PP), polyamide (PA), polyurethane (PU), acrylonitrile butadiene styrene (ABS), polylactate (PLA), polymethylmethacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polystyrene (PS), polyetheretherketone (PEEK), polyvinyl chloride (PVC).

8. Woven fabric according to claim 1, characterized in that the first, second and third warp threads (11, 13, 12) as well as preferably also the weft threads (16) comprise such a width and are woven into the woven fabric in such a manner so that the third warp threads (12) are enclosed completely by the first and second warp threads (11, 13) as well as the weft threads (16).

9. Woven fabric according to claim 1, characterized in that the first and second warp threads (11, 13) are at least exactly as wide as the third warp threads (12) and in that the first and the second warp threads (11, 13) completely cover the third warp threads (12) in top plan view and in bottom plan view.

10. Woven fabric according to claim 1, characterized in that in addition to the first, second and third warp threads (11, 13, 12) at least fourth warp threads are present, which are arranged always between the first and second warp threads (11, 13) and always in the same constant position, that is to say either above or below, with respect to the third warp threads (12) in the woven fabric.

11. Method for producing a multilayered woven fabric of warp and weft threads by means of a weaving machine, wherein the method encompasses the following steps:

a plurality of warp thread bundles that run next to one another in the weft thread direction and that at least consist of first, second and third warp threads (11, 13, 12) respectively running above one another, are supplied to a shedding arrangement,

in its weaving cycles, the shedding arrangement opens alternating sheds between the respective at least three warp threads as well as below and above these, in order to guide weft threads (16) through these sheds,

wherein the third warp threads (12) consist of a different material than the first and the second warp threads (11, 13), and

wherein the first and second warp threads (11, 13) preferably contain a thermoplastic material, while the third warp threads (12) preferably contain a high performance material, for example carbon or glass.

12. Method according to claim 11, characterized in that as the material for the first and/or the second warp threads (11, 13) and/or the weft threads (16) at least one thermoplastic material is used, which is selected from one or more members of the following group: olefin homo- or copolymers, for example polyethylene (PE) or polypropylene (PP), polyamide (PA), polyurethane (PU), acrylonitrile butadiene styrene (ABS), polylactate (PLA), polymethylmethacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polystyrene (PS), polyetheretherketone (PEEK), polyvinyl chloride (PVC).

13. Method according to claim 11, characterized in that in addition to several heddles (1) of the weaving machine arranged next to one another in weft direction (S), behind at least some of the abovementioned heddles (1), heddles (2, 3) arranged in the warp direction (K) behind at least some of the abovementioned heddles (1) are provided, and in that respectively at least one warp thread (11, 12, 13) is guided through each one of the heddles (1, 2, 3) respectively arranged behind one another in such manner, whereby several warp threads (11, 12, 13) are guided above one another in the warp direction (K), whereby the heddles (1, 2, 3) arranged behind one another respectively in a row are alternately repeatedly moved upward and downward and are thereby individually positioned in Z-direction, whereby one after another different loom sheds (35, 36, 37, 38) are realized between warp threads (11, 12, 13) running above one another, through which weft threads (16) are inserted.

14. Method according to claim 13, characterized in that it encompasses the following steps:

at least one front heddle (1) arranged closer to the machine outlet in the running direction of the warp threads (11, 12, 13) with at least one, preferably exactly one, heddle eye (21) with smaller height for threading through a first warp thread (11) and deflecting this first warp thread (11) through a repeated upward and downward movement in Z-direction, and with at least one elongated hole (31a) with larger height that extends in Z-direction and that is arranged above or below the said at least one heddle eye (21) for the position-fixed or deflection-free through-guiding of at least one second warp thread (13), is provided,

at least one rear heddle (3) arranged behind the front heddle (1) and closer to the machine inlet in the running direction of the warp threads (11, 12, 13) with at least one, preferably exactly one, heddle eye (23) with smaller height for threading through the said second warp thread (13) and deflecting this second warp thread (13) in Z-direction, and with at least one elongated hole (33b) with larger height that extends in Z-direction and that is arranged above or below the said at least one heddle eye (23) for the position-fixed or deflection-free through-guiding of at least the said first warp thread (11), is provided,

at least one middle heddle (2) is provided in said rows of heddles (1, 2, 3) between the said front and rear heddle (1, 3) for the guiding in Z-direction of then in total at least three warp threads (11, 12, 13) running above one another, whereby this at least one middle heddle (2) comprises at least one, preferably exactly one, heddle eye (22) for the guiding and deflecting of an associated third warp thread (12) and an elongated hole (32a) above and an elongated hole (32b) below its respective said at least one heddle eye (22) for the deflection-free through-guiding of at least the first and second warp threads (11, 13), whereby the first and the second warp thread (11, 13) in running direction of the warp threads are threaded through the respective at least one heddle eye (21, 23) of the front or respectively rear heddle (1, 3) or of the rear or respectively front heddle (3, 1), and the remaining warp threads (12) lying between the first and second warp thread (11, 13), thus the third warp thread (12) in the case of only one middle heddle (2), are guided in increasing or decreasing sequence through the respective at least one heddle eye (22) of the middle heddle (2),

loom sheds (35, 36, 37 38), alternately defined by repeated reciprocal relative movements of the front, the at least one middle and the rear heddle (1, 2, 3) in Z-direction, are formed between the at least three first, second and third warp threads (11, 13, 12) running above one another, for the purpose of the weft insertion.

15. Method according to claim 11, characterized in that the third warp threads (12) are covered completely from above and from below by the first and second warp threads (11, 13) as well as the weft threads (16).

16. Method according to claim 11, characterized in that the mass or volume ratio of third (12) to first and second warp threads (11, 13) is set to be constant over the entire woven fabric surface, wherein this ratio is especially adjustable by the selection of the thickness of the first and second warp threads (11, 13).

17. Method for processing a woven fabric according to claim 1, wherein the woven fabric (18) is applied by draping onto a curved or otherwise configured three-dimensional structure.

18. Method for processing a woven fabric according to claim 1, wherein the first and second warp threads (11, 13) as well as preferably at least some of the weft threads (16) contain at least one thermoplastic material, wherein through heating above the melting point of the at least one thermoplastic material, the woven fabric is transformed into a three-dimensional shaped structural component.

19. Shaped structural component produced by the method according to claim 18.