WOVEN FABRIC COMPOSED OF TAPE-LIKE WARPS AND WEFTS

Abstract

A novel woven fabric is provided wherein preferably two unidirectional mutually offset and at least partly overlapping layers of tape-like warps interlace with tape-like wefts, at least some being fibrous tapes, that are incorporated individually in either non-overlapping manner or in a mutually offset and overlapping manner relative to other weft tapes. Such a woven fabric is without see-through gaps at the areas/sites encircled by intersecting tape-like warps and wefts, and also delamination resistant. It is particularly suitable for composite material, ballistic mitigation, and similar applications.

Claims

1. A woven fabric comprising tape-like warps and wefts, at least some of which are fibrous tapes, wherein the warps and wefts interlace, and wherein the warps and/or the wefts are arranged in at least two unidirectional and at least partly overlapping layers, wherein at least one warp/weft of one layer is offset in relation to warps/wefts in the other layer so that the offset warp/weft overlies and covers at least one longitudinal gap between adjacent warps or wefts in the other layer.

2. The woven fabric of claim 1, wherein all warps or wefts of the two respective layers are offset in relation to each other.

3. The woven fabric of claim 1, wherein each of the warps and the wefts are provided in such at least two layers.

4. The woven fabric of claim 1, wherein the warps are provided in said at least two layers, and wherein at least some warps in these layers are grouped in units of grouped warps whereby each weft interlaces with the units of grouped warps.

5. The woven fabric of claim 4, wherein units of grouped warps are interlacing with individual tape-like wefts wherein the individual tape-like wefts are incorporated in a mutually offset and overlapping arrangement relative to each other.

6. The woven fabric of claim 1, wherein the fabric is free from see-through gaps or openings at areas encircled by intersecting warp tapes and weft tapes.

7. The woven fabric of claim 1, wherein the fibrous tapes are tapes in which the fibers are substantially unidirectional in orientation.

8. The woven fabric of claim 1, wherein all the tape-like warps and wefts are fibrous tapes.

9. The woven fabric of claim 1, wherein said interlacing warp and weft tapes occurs mutually above, below and in between said overlapping layers.

10. The woven fabric of claim 1, wherein the warps are provided in said at least two layers, and wherein the interlacing of the weft occurs in such a way that at least some weft(s) runs in a path above, below and in between said overlapping warp layers.

11. The woven fabric of claim 1, wherein it has an areal weight in the range 40-4000 grams/sq. m.

12. The woven fabric of claim 1, wherein it has a fabric thickness in the range 0.02-5 mm.

13. The woven fabric of claim 1, wherein the width of the warp and weft tapes are in the range of 5-100 mm.

14. The woven fabric of claim 1, wherein the fibrous tapes have a count in the range of 1 k to 60 k.

15. The woven material of claim 1, wherein the fibrous tapes have a count in the range of 50-5000 Tex.

16. The woven fabric of claim 1, wherein it has a crimp frequency in the range of 10/m to 75/m.

17. The woven fabric of claim 1, wherein it has a crimp angle in the range of 0 to 10.

18. The woven fabric of claim 1, wherein the woven fabric is a reinforcement for use in a composite material.

19. A method for producing a woven fabric comprising the steps: providing a set of fibrous tape-like warps; creating a shed in warps; inserting fibrous tape-like wefts in the created shed; wherein the steps are performed to interlace warp tapes and weft tapes, and wherein the step of forming a shed involves usage of at least some units of grouped warp tapes, each of such units of grouped warp tapes having at least two tapes that are mutually offset and overlapping, the tapes extending longitudinally and unidirectionally, whereby at least one of the warp tapes from one layer overlies and covers a gap existing between adjacent longitudinal edges of warp tapes of the other layer.

20. The method of claim 19, further comprising the step of advancing the produced fabric, wherein the fabric is advanced by a distance whereby the wefts are enabled to be incorporated in the fabric in either a non-overlapping manner or in a mutually offset and overlapping manner relative to other weft tapes.

21. The method of claim 19, wherein the step for creating a shed enables a shed to be created over a previously laid weft to incorporate the new weft in a mutually offset and overlapping manner relative to the previously laid weft.

22. The method of claim 19, wherein the step of inserting tape-like wefts in the created shed is further preceded or followed by at least one of the sub-steps: cutting tape-like wefts; positioning laid wefts at fabric-fell; and winding up the paid-out/advanced fabric into a roll.

23. An apparatus for producing a woven fabric comprising: a warp holding arrangement providing fibrous tape-like warps; a shed forming device for creating sheds in the warps; and a weft inserting device for insertion of fibrous tape-like wefts in the created shed; wherein the said shed forming device and weft inserting device perform interlacing of warp tapes and weft tapes, and wherein the shed forming device is arranged to create a shed involving usage of at least some units of grouped warp tapes, each of such units of grouped warp tapes having at least two tapes that are mutually offset and overlapping, the tapes extending longitudinally and unidirectionally, and at least one of the warp tapes from one layer overlies covering the gap existing between the adjacent longitudinal edges of the warp tapes of the other layer.

24. The apparatus according to claim 23, further comprising means for advancing the produced fabric whereby the shed forming device is arranged to enable a shed to be created over a previously laid weft to incorporate the new weft in a mutually offset and overlapping manner relative to the previously laid weft.

25. Use of a woven fabric in accordance with claim 1 as a reinforcement in a composite material.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0071] For exemplifying purposes, the invention will be described in closer detail in the following with reference to embodiments thereof illustrated in the attached drawings, wherein:

[0072] FIGS. 1a and 1b show the warp tapes arranged in a two unidirectional mutually offset and at least partly overlapping layers in accordance with an intermediate step of forming a woven fabric of an embodiment of the present invention.

[0073] FIGS. 2a-2b show displacement of select tape-like warps in the two layers of FIG. 1 to create a shed, as a further step in forming the woven fabric.

[0074] FIG. 3 shows the weft inserted in the created shed of FIG. 2a.

[0075] FIGS. 4a-4c show an exemplary embodiment of the production of a woven fabric by interlacing of the two-layered mutually offset and overlapping fibrous tape-like warps with individual non-overlapping fibrous tape-like wefts in accordance with an embodiment of the invention, and the produced fabric's cross-sectional structure.

[0076] FIG. 5 shows one example of the novel woven fabric wherein two-layered mutually offset and overlapping fibrous tape-like warps interlace with fibrous tape-like wefts that are incorporated individually in a mutually offset and overlapping manner relative to other weft tapes.

[0077] FIGS. 6a-6d show an example of a sequence of some steps of incorporating different wefts in the woven fabric of a weave pattern, in accordance with another embodiment of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0078] In the following detailed description, preferred embodiments of the present invention will be described. However, it is to be understood that features of the different embodiments are exchangeable between the embodiments and may be combined in different ways, unless anything else is specifically indicated. It may also be noted that, for the sake of clarity, the dimensions of certain components in the drawings may differ from the corresponding dimensions in real-life implementations of the invention. Even though in the following description, numerous illustrated specific details are set forth to provide a more thorough understanding of the present invention, it will be apparent to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well known constructions or functions are not described in detail, so as not to obscure the present invention.

[0079] The novel woven fabric, according to one embodiment, may be realized by supplying fibrous warp tapes preferably at least in two unidirectional mutually offset and at least partly overlapping layers arrangement as shown in FIGS. 1a and 1b. The two layers of tapes comprise the first set of tapes W11-W15 and the second set of tapes W21-W24. As shown in FIGS. 1a and 1b, the two sets of warps are supplied in a mutually offset manner such that the gap between the adjacent longitudinal edges of two tapes of the first set are covered by a longitudinal mid-part of a tape of the other set, and vice-versa. For example, the gap between the adjacent longitudinal edges of the tapes W11 and W12 is covered by a longitudinal mid-part of tape W21. FIG. 1b represents the end view of the mutually offset arrangement of the tapes indicated in FIG. 1a.

[0080] The mutually offset and overlapping layers of warp tapes extend in parallel longitudinal directions, with gaps formed there between also extending longitudinally. The warp tapes may be arranged very close to each other, thereby forming narrow longitudinal gaps, or be more displaced from each other, thereby forming more pronounced longitudinal gaps. The gaps formed between the different warp tapes may be of the same or varying width. However, preferably, the width of the gaps is less than the width of the warp tape. Preferably the gap is less than 50% the width of the warp tape/s, and most preferably less than 20% of the width of the warp tapes.

[0081] As can be observed now, by the mutually offset and overlapping arrangement of the warp tapes, and taking into consideration the width of the individual warp tapes used and the width of the longitudinal gaps between adjacent warp tapes, the warp tape/s of one layer can lie over at least one longitudinal gap between adjacent warps in the other layer. Preferably, all the warp tapes are arranged in this way to cover all the longitudinal gaps.

[0082] In the illustrative embodiment of FIG. 1, the mutual offset between overlapping warp tapes (all of which are indicated to be of the same width), for example W11 and W21, W12 and W22 etc., is less than 50% the width of the warp tapes. By such offset the longitudinal gaps between warp tapes, for example W21 and W22, W22 and W23 are covered centrally by the respective tapes W11 and W12. However, other offset distances are also feasible. For example, the offset may be as low as 5-20%, particularly when the gaps are required to be relatively narrow.

[0083] It may be noted that because the two layers of fibrous tape-like warps are supplied in a mutually offset arrangement, the number of tape-like warps in a first set could be greater by one than the number of tape-like warps in the other set. However, one may also use equal number of tapes in both layers in the mutually offset supply of the tape-like warps. In both these instances, if required, the non-doubled longitudinal part of one or both the outermost warp tapes can be made double-layered through use of relatively narrower tapes, for example to achieve over all greater uniformity in woven material's thickness.

[0084] The supplied mutually offset fibrous tape-like warps are subjected to shedding using a suitable method and means. Depending on the weave pattern to be created, tape-like warps, at least one each from both the layers, for example (W11, W21) and (W12, W13, W22) shown in FIG. 2a, are selected to function as a unit of grouped warp tapes for crossed-separation to create the shed. Each of such units of grouped warp tapes, as also an individual warp tape, involved in shedding are henceforth referred to here as unit warp. It may be noted that the tapes selected in one unit warp during a particular shed formation could be different from that in the subsequent shed formation. Thus, while (W11, W21), (W12, W13, W22), (W14, W23, W24), (W15) in FIG. 2a function as selected units of warps for being suitably displaced to create a shed, for the subsequent shed formation the warp tapes selected in units of warps would comprise different tapes, for example (W11, W12, W21), (W13, W22, W23), (W14, W15, W24), as shown in FIG. 2b. As can be noticed, the number of tapes in a given unit warp can be different from that of another unit warp. In the illustrative example of FIG. 2a, the shed is formed by units of warps in each of which are different numbers of tapesunit of grouped warp tapes W11 and W21 (two tapes); unit of grouped warp tapes W12, W22 and W13 (three tapes); unit of grouped warp tapes W23, W14 and W24 (three tapes); and unit of warp tape W15 (one or single tape). Differing numbers of warp tapes are selectable in this weaving method, as desired, from the two layers to form units of grouped warp tapes for shedding. The step for shedding thus involves usage of at least some units of grouped warp tapes each of which may be composed of either same or differing numbers of tapes in accordance with the weave pattern being created.

[0085] A fibrous tape-like weft T1, shown in FIG. 3, is subsequently suitably inserted into the created shed, preferably in a flat condition, using any of the known weft inserting methods and means. The tape-like wefts are laid individually but are incorporated in the fabric in either non-overlapping manner or in a mutually offset and overlapping manner relative to other weft tapes. Whereas the non-overlapping manner of weft incorporation is achieved by setting the fabric take-up to advance the fabric by a length that is at least the width of the weft tape inserted, the mutually offset and over-lapping manner of weft incorporation is achieved by setting the fabric take-up to advance the fabric by a length that is less than the width of the weft tape inserted. For example, the length of fabric advancement when incorporating wefts in a non-overlapping manner can be 50% more than the width of the inserted weft, and when wefts are to be incorporated in a mutually offset and overlapping manner it could be even less than 50% of the width of the inserted/laid weft. A less-than-the-width-of-weft distance of fabric advancement for incorporating wefts tapes in a mutually offset and overlapping manner is possible because the weaving method uniquely allows creation of a shed with units of grouped warp tapes whereby the subsequent weft tape can be incorporated over an already inserted weft tape as the previously inserted weft tape will exist in a plane under the newly created shed.

[0086] As can be inferred now, a woven fabric is producible wherein the two-layered mutually offset and overlapping fibrous tape-like warps (i.e. units of grouped warps) and the individual fibrous tape-like weft T1 interlace as shown in FIG. 4a and create the gap-free woven fabric according to the present invention. FIG. 4b shows a woven fabric wherein individual fibrous tape-like wefts T1-T3 are incorporated in the non-overlapping manner. Subsequent weft tapes are incorporated in a corresponding repeating manner to continuously produce a large fabric. Although these weft tapes occur successively (i.e. without being mutually offset and overlapping each other) in the usual way, there is still no see-through gap created in the fabric due to the presence of overlapping warp tapes.

[0087] In FIG. 4c is represented the path of a fibrous tape-like weft, for example that of T1 (shown in FIGS. 4a and b), when interlacing with different units of grouped warp tapes. The illustrative example in FIG. 4c shows a weft running first, when seen from left to right, above the warps, then between the warp layers, then below the warps, then again between the warp layers, then above the warps and finally between the warp layers. Preferably each subsequent weft also runs similarly in different paths and thereby forming a strong mechanical interconnection to resist delamination of warp-weft layers in the fabric.

[0088] After insertion of the fibrous tape-like weft through the shed is completed, subsequent operations relating to beating-up/positioning of the individual tape-like wefts towards the fabric-fell position, taking-up/advancing forward the produced fabric as discussed in the foregoing, and winding-up the paid-out fabric onto a roll, may be performed using known methods and means to complete a full weaving cycle. New cycles may then be performed to produce a larger fabric continuously.

[0089] Thus, subsequent to the optional weft beating-up, fabric taking-up, fabric winding-up etc., the next weaving cycle commences wherein the required select units of grouped warp tapes are displaced to create the following new shed into which the new tape-like weft is inserted. These various weaving operations are performed in required order cyclically to produce the novel gap-free and delamination resistant woven fabric in a continuous manner.

[0090] As can be inferred now, a woven fabric is produced wherein the gaps/openings at the areas/sites encircled by intersecting fibrous tape-like warps and wefts are, at least to some extent and preferably fully, get covered by the tapes of the two-layered mutually offset and overlapping tape-like warps. As a result, the gaps/openings in the fabric become invisible. Also, the warp-weft layers in the fabric are interconnected to resist delamination. Further, the relatively thin and wide fibrous tapes have extremely low crimp frequency and/or crimp angle.

[0091] Following the outlined weaving procedures, one example of a woven fabric composed of mutually offset and overlapping fibrous tape-like warps and tape-like wefts T1-T4 that are incorporated individually in a mutually offset and overlapping manner relative to other weft tapes is exemplified in FIG. 5. By incorporating both the tape-like warps and wefts in a mutually offset and overlapping manner, even if the spacing between the longitudinal edges of the adjacent tapes in the warp and weft directions is more than 50% of the width of the tapes used in a given direction, there will be no see-through gaps. FIGS. 6a-6d represent the stepwise different paths of mutually offset and overlapping wefts T1-T4 incorporated in the woven fabric corresponding to that shown in FIG. 5. FIG. 6a illustrates the path of a first weft T1. FIG. 6b illustrates the paths of wefts T1 and T2 in a cross-section where T1 and T2 are incorporated in mutually offset and overlapping configuration. FIG. 6c illustrates the paths of wefts T2 and T3 in a cross-section where T2 and T3 are incorporated in mutually offset and overlapping configuration. FIG. 6d illustrates the paths of wefts T3 and T4 in a cross-section where T3 and T4 are incorporated in mutually offset and overlapping configuration.

[0092] It may be pointed out here that the described supply arrangement of mutually offset and overlapping tape-like warps is not limited to only two tape layers as illustrated herein. Additional one or more layers of tapes can be also supplied suitably in the indicated offset arrangement, and the weaving operations similarly performed as described, to obtain a relatively thicker, gap-free and unified delamination resistant woven fabric. Here again, individual tape-like wefts, in either non-overlapping manner or in a mutually offset and overlapping manner relative to other weft tapes, can be used.

[0093] It may be noted that by weaving of units of grouped warp tapes with tape-like wefts in a mutually offset and overlapping manner relative to other weft tapes either balanced or unbalanced woven fabrics can be obtained according to the performance requirements by varying desired parameters such as tape widths, tape thickness, spacing between warp tapes, spacing between weft tapes, weave patterns, take-up rates etc. Needless to state, a person skilled in the art will also understand now that a woven fabric comprising single-layered, or non-overlapping, tape-like warps can be used and interlaced with tape-like wefts which are incorporated in a mutually offset and overlapping manner relative to other weft tapes to produce a fabric that is also free of see-through gaps and delamination resistant. It will be also apparent now that through use of relatively thinner but doubled warp and/or weft tapes, fabrics which are either thicker or heavier in areal weight are directly producible. Likewise, it is also possible to obtain a woven fabric comprising non-fibrous and fibrous tapes.

[0094] Further, the described novel tape-woven fabric could be used, depending on application and/or product requirements, in any required orientation. For example, a cut-sheet oriented 45 relative to the warp (or weft) direction could be used as a bias material. Or, a cut-sheet could be draped in a way to occur in either two mutually perpendicular planes or three mutually perpendicular planes. Still further, it could be used to drape in double curvature. Such cut-sheets could be also stacked in relatively different orientations to create a multidirectional material. Still further, such cut-sheets could be combined with other existing types of fabrics to benefit from the advantageous features of the tape-woven fabric according to the described invention.

[0095] Further, as already mentioned above, the longitudinal gaps between edges of adjacent tapes may have either the same or different widths, and may be relatively large or relatively small. Further, the tapes used in the fabric may have either a relatively large or a relatively small width. A fabric may also be produced using tapes of different widths. For example, it is possible to use one width for the tapes forming the warps, and a different width for the tapes forming the wefts. It is also possible to use warps and/or wefts having different widths. Still further, the tapes may be of the same or different materials. It is also possible, as will be appreciated by the skilled addressee, to provide many different weave patterns.

[0096] Such and other obvious modifications must be considered to be within the scope of the present invention, as defined by the appended claims. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the spirit and scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting to the claim. The word comprising does not exclude the presence of other elements or steps than those listed in the claim. The word a or an preceding an element does not exclude the presence of a plurality of such elements. Further, a single unit may perform the functions of several means recited in the claims.