Woven tape for woven zip-fasteners

Abstract

 A woven tape for woven zip-fasteners which carries a preformed spiral of a synthetic single thread which is connected by interweaving to the tubular edge of the tape.
The tape is composed of the interlacing of the warp threads (0) with two double weft threads (S, T). These wefts (S,T) diverge in the edge area of the tape (B, C) to form upper (B) and lower (C) flaps (B, C) for the spiral (D) and are united together again by being interlaced with the warp threads (0₁₁₁) which are common to both wefts (S, T) to close the open side of the flaps (B, C) and to provide a tubular edge (B, C).

Description

[0001] This invention relates to woven zip-fasteners and more particularly relates to a woven tape carrying a spiral which forms connection members and intended to be used in combination with a second identical tape and with an appropriate slider to provide a zip-fastener of the kind referred to above.

[0002] Woven tapes which are equipped in correspondence with either longitudinal edge with a continuous spiral of a plastics material or of any other material adapted to be properly deformed so as to provide an array of connection members are known in a number of embodiments.

[0003] The tape according to the present invention belongs to that class which provides for securing the spiral, or helix, already previously formed, by interweaving during the formation of the tape itself.

[0004] Such tapes usually present two zones which are sharply distinguished from one another, viz.; a zone of tape proper with a single fabric layer, and a second edge zone, usually narrower than the former, which has two fabric edges or flaps, the preformed spiral being inserted therebetween, and secured in position.

[0005] If both these zones of the tape are pade with a single weft, it is apparent that in the edge area there are a number of bindings with the relevant warp threads which is one half of the number of bindings in the area of the tape proper.

[0006] Stated another way, in the edge area the weft alternately contributes towards the formation of the upper and the lower layer or edge of the fabric so that these two layers or edges are weakened and thus are less resistant than the area of the tape proper.

[0007] In order that these shortcomings might be offset, it had already been suggested to form the tape with two wefts, so as to have, for each insertion of the weft threads the binding of all of the warp threads in the two fabric layers in the edge area of the tape. The preformed spiral inserted between the two flags of the tape, in this case, is secured by means of the warp threads, the so-called binders, which encompass the individual spirals of the coiling and cross each other in correspondence of the gaps which separate consecutive preformed hooking projections on each spiral of the coiling. In the edge area of the tape there are consequently warp threads which, with their respective wefts, make up the two fabric layers which are the covering flaps for the spiral, while other warp threads are bound with both wefts and connect together the two fabric layers so as to clamp the spiral therebetween.

[0008] Now, for dimensional reasons, the number of warp threads in the edge area of the tape is limited of necessity and thus only a small number of warp threads can be exploited to the end of binding and securing the coiling. This fact is a drawback and may entail an unsafe connection of the spiral to the supporting tape. It should be borne in mind that the edge area is subjected to a considerable wear by the slider which glides on the connection members so that one or more warp threads may become unravelled and prejudice the firmness of the connection between the spiral and the tape.

[0009] An object of the present invention is to provide a tape for woven zip-fasteners which guarantees a firmer and more reliable connection between the zip spiral and the tape while retaining all the advantages inherent in the known tapes of the kind referred to.

[0010] This object is achieved according to the invention by a woven fabric tape formed by two weft threads and a plurality of warp threads and comprising a longitudinal area with a single woven layer and a tubular longitudinal edge area with two superposed woven layers connected to one another for closing the tubular edge, said longitudinal edge tubular area carrying a preformed spiral composed of a comparatively stiff thread having flattened deformed spirals each having a hooking tooth, in the single woven layer area both the weft threads being bound with at least a part of a common group of warp threads and in the tubular edge area the two weft threads being set apart from one another and being bound with respective discrete warp threads to form two superposed woven layers, the tape being characterized in that in the tubular edge area at least one of the weft threads bound with the group of warp threads of one of the two superposed woven layers is passed, according to a preselected sequential order, to become bound with at least one warp thread belonging to the group of warp threads of the other layer thus forming the closure of the tubular edge.

[0011] By so doing, the preformed spiral becomes retained and bound to the longitudinal tubular edge area of the tape by virtue of the cooperation of the two weft threads instead of by the agency of warp threads. On bearing in mind the circumstance that the number of insertions (picks) of weft threads per linear centimetre of tape is rather high, and also on taking into account the fact that the tape is formed by two weft threads, the binding of the spiral is extremely firm and is much more reliable than the one which would have been obtained by utilizing to that purpose the few warp threads which can be employed in the tape edge area. As a matter of fact, even if one or more weft picks might become broken due to wear, the binding of the zip spiral would be fully warranted by the other weft picks.

[0012] According to an embodiment of the tape according to the invention, either of the two woven layers of the tubular edge is entirely formed with either of the two weft threads and with a group of weft thread, while the other layer of fabric is entirely formed by the other weft thread and with a second group of warp threads and the weft thread which forms either of the two layer is bound also with at least one warp thread belonging to the group of the other of the two layers. In this case, said at least one warp thread belonging to the group of the other of the two layers may be composed of the last warp thread of such group away of the common warp thread group which forms the single woven layer zone, or it can be formed by a warp thread of said group more or less closely adjacent to the common warp thread group forming the single woven layer area.

[0013] It is possible, if so desired, to have the rear surface of the spirals of the zip coil, where the slider runs, either covered by a coating fabric, or uncovered.

[0014] In both cases, it is also possible to provide at least one connection warp thread which passes to be bound alternately to the two woven layers of the tubular edge so as to keep them tucked against the spirals of the zip coil.

[0015] According to another embodiment it is also possible to form the two superposed woven layers of the tubular edge, according to a preselected sequential order, both with either, or the other, of the two weft threads in cooperation with two discrete groups of warp threads in such a way that the portions of the weft threads in the transition area from the binding which a warp thread of a group to the binding with a warp thread of the other group form the closure of the tubular edge.

[0016] Obviously, in the interior of the zip spiral a filler or cushioning thread may be conventionally provided and the position of the zip spiral relative to the plane of the single woven layer area of the tape may be either symmetrical or asymmetrical.

[0017] Another possibility, which is conventional as itself, is to provide a cushioning externally of the zip coil spirals on the side away of the hooking members, for example by thickened warp threads.

[0018] At any rate, the weft and warp threads used for the formation of the tape can have the same count of yarn or not.

[0019] A few exemplary embodiments of the tape according to the invention will now be described in more detail hereinafter with reference to the accompanying drawings, wherein :

FIGURE 1 diagrammatically shows in cross-sectional view a woven tape according to a first embodiment.

FIGURE 2 is a plan bottom view of the tape shown in FIGURE 1.

FIGURE 3 shows a woven tape akin to that of FIGURE 1, but having a symmetrical configuration.

FIGURES 4 and 5 show two alternative embodiments of the tape shown in FIGURE 1, and

FIGURES 6 and 7 show, in cross-sectional and in plan view, respectively, another embodiment of the tape.

[0020] It should be borne in mind that, in the FIGURES of the drawings which show the tape in cross-sectional view, the weft threads are shown with reference to two consecutive picks, as can be seen in the attendant plane views, in order to facilitate the understanding. Such an illustration is conventionally used.

[0021] In addition, inasmuch as the woven tape is appropriately produced on a needle loom, the weft threads, although they have been shown in cross-section with single lines, must be intended to be in double line.

[0022] The woven tape shown in FIGURES 1 and 2 is of the asymmetrical type, that is with the zip spiral providing the hooking members arranged entirely along either side of the tape. As can clearly be seen, the tape comprises a longitudinal area with a single woven layer, A , and a longitudinal tubular edge area with two superposed woven layers, B and C. The longitudinal edge area carries a preformed zip coil D which is composed of a comparatively stiff thread, preferably a synthetic single thread, with deformed spirals, E, which are flattened and each fitted with a hooking tooth F.

[0023] The tape is formed with two weft threads, S and T: there have been indicated by S₁ and T₁ the portions of the weft threads S and T which are picked together during a picking step, and by S₂ and T₂ there have been indicated the relative thread portions inserted during a subsequent picking step.

[0024] In the longitudinal single woven layer area of the tape A, both the weft threads S and T are bound to a group 0_I of warp threads 0₁, 0₂......0₈, whereas in the tubular edge area of the tape the weft threads are ; split apart: the weft thread S is bound to a group 0_II of warp threads 0₉, 0₁₀...0₁₅, and the weft thread T is bound to a group 0_III of warp threads ⁰₁₆, 0₁₇ ...0₂₅. The number of warp threads which compose each group such as 0_I, 0_II and 0_III is merely indicative and can be selected at leisure.

[0025] It is apparent that the group 0_II of the warp threads which are bound to the weft thread S provides either of the two woven layers of the edge area, and exactly the bottom layer of cover B, whereas the group 0₁₁₁ of warp threads which is bound to the weft thread T provides the other layer, that is, the upper layer or cover C.

[0026] Characteristically, according to the invention, for closing the tubular edge, that is to connect together the two superposed layers B and C in the edge area, at least either of the two weft threads, in the case shown in FIGURES 1 and 2 the weft thread T bound to the group 0_III of warp threads of the upper woven layer C, is bound at each picking step with at least one, in the example shown with two warp threads, 0 ₉ and 0₁₀ belonging to the group 0_II of the warp threads of the bottom woven layer B.

[0027] In the-embodiment according to FIGURES 1 and 2, the two warp threads 0₉ and 0₁₀ of the group 0_II to which also the weft thread T is bound, are the last threads of said group 0_II away of the group 0_I of warp threads forming the single layer area A.

[0028] In the interior of the zip coil D there is inserted a cushioning stuffing cord G running in the direction of the warp threads.

[0029] The preformed zip coil D is retained and bound to the tubular edge area of the tape by the coaction of the two weft threads S and T and, more detailedly in the case shown in FIGURES 1 and 2, by the portions of the weft thread T which, from the group 0_III of the warp threads become bound to the warp threads 0₉ and 0₁₀ of the group 0₁₁. Thus a safe and reliable bond is obtained since even the possible rupture of one or more port- tions of the weft thread T by wear leaves the spiral D firmly bonded to the other picks of the same weft thread.

[0030] The embodiment of the tape shown in FIGURE 3 fully corresponds to that described hereinabove, with the exception that as a result of the selection of an equal number of warp threads forming the two groups 0₁₁ and 0₁₁₁ and of a resultant particular geometrical weaving arrangement which is conventionally known, the middle plane of the zip coil D coincides with the plane of the single layer area A of the tape, that is to say that the zip coil is in a symmetrical position relative to the supporting tape. In FIGURE 3 there have been used the same reference numerals as in the previous FIGURES for indicating portions of the tape which are the same as those described previously.

[0031] FIGURE 4 shows an embodiment which is akin to that shown in FIGURES 1 and 2. A difference, however, consists in that a warp thread H is provided, which alternately belongs to the group 0₁₁ and to the group 0₁₁₁ of the warp threads. By so doing, the warp thread H provides to keep that two woven layers B and C of the tubular edge closely adherent to the spirals E of the zip coil D. Obviously, the warp thread H must be fed in a length which is longer than those adopted for the other warp threads. Another difference is the absence of a cushioning cord. In this case, the preformed zip coil D is secured to the tubular edge of the carrier tape by virtue of the interlocking of the portions of the weft thread T, which are bound to the warp threads of the woven layer formed with the other weft thread S, with the spirals E of the zip coil D.

[0032] In the embodiments described hereinabove, the rear portion of the spiral D away of the hooking teeth F and where the slider glides was covered by a covering fabric.

[0033] FIGURE 5 shows an embodiment in which said rear portion of the zip coil is uncovered.

[0034] In this case, the group 0₁₁₁ of the warp threads which being bound to the weft thread T form the upper woven layer C of the edge area is composed of a small number of warp threads, for example only three, as shown. The weft thread T, after having contributed towards forming the single woven layer area A by becoming bound to the warp threads of the group 0₁, is interlaced with the portion of zip coil thread between the consecutive spirals E of the zip coil D and become bound also to warp threads belonging to the group 0₁₁ which pertain to the lower layer B of the edge and is then bound to the warp threads of the group 0_III which belong to the upper layer C. The last warp thread H of this group 0_III is a binding thread since it alternately passes to belong to the group 0_II.

[0035] Another embodiment of the tape according to the invention is shown in FIGURES 6 and 7. Also in this embodiment, which is of the symmetrical class, the tape comprises a single woven layer area A, and a tubular area having two superposed layers of fabric B and C. The tape also comprises two weft threads S and T which are bound to a group 0₁ of warp threads 0₁, 0₂.....0₇ form together the single woven layer A.

[0036] Differently from the embodiments described hereinabove, in this case the two superposed woven layers B and C of the tubular edge are not formed, each, only with one of the two weft threads, but the formation of these two layers B and C is brought about, according to a preselected sequential order, for example by alternate picks, by both the weft threads S and T in cooperation with two discrete groups 0_II and 0₁₁₁ of warp threads 0₉, 0₁₀.....0₁₅, and 0₁₆, 0₁₇.....0₂₂, respectively. Stated alternatively, as can otherwise be seen in FIGURES 6 and 7, during a picking step the weft thread S₁ is bound to the group 0_II of warp threads and the weft thread ^T_l is bound to the group 0_III of warp threads, whereas, during the subsequent picking step, the weft thread S₂ is bound with the group 0₁₁₁ of warp threads and the weft thread T₂ is bound to the group 0₁₁ of warp threads, and so forth.

[0037] By so doing, after each picking step, the portions of the two weft threads S and T which pass from the binding with a warp thread 0₉ of a group 0₁₁ (or, respectively, with the warp thread 0₁₆ of the group 0_III) to the binding with a warp thread 0₁₆ of the other group 0₁₁₁ ( or, respectively, with the warp thread C₉ of the group 0_II) form the closure of the tubular edge of the tape while concurrently securing the zip coil D to said edge.

[0038] In the example shown, a stuffing cord G has been provided, but it could also be dispensed with.

[0039] The invention has been shown and described with reference to a few nonlimiting examples which may undergo a number of changes and which can also variously be combined with each other.

[0040] As a matter of fact, one of the principal advantages afforded by the present invention is just the fact that a great versatility is permitted.

[0041] Thus, the diameters of the warp threads forming the tape, and their number can be varied and the same is true of the diameter of the two weft threads and their kind which can be different from one another, it being likewise possible to vary with facility the external configuration of the carrier tape, especially when, by making the zip fastener asymmetrical, it is possible completely to conceal on one side the row of the hooking members by properly extending the covering side on the edge area of the tape.

[0042] Consistently with the individual requirements, it is possible to mask the rear portion of the zip coil or to unmask it to guide the slider properly. In the case of covering the rear portion of the zip coil, it might be appropriate in certain cases to resort to an external cushioning.

[0043] The reliability of the union of the zip coil to the tape edge is fully satisfactory even if the zip fastener is subjected to an intensive wear.

[0044] The textile pattern of the tape, obviously, can be selected at leisure.

Claims

1. A woven fabric tape formed by two weft threads and a plurality of warp threads and comprising a longitudinal area with a single woven layer and a tubular longitudinal edge area with two superposed woven layers connected to one another for closing the tubular edge, said longitudinal edge tubular area carrying a preformed spiral composed of a comparatively stiff thread having flattened deformed spirals each having a hooking tooth, in the single woven layer are both the weft threads being bound with at least a part of a common group of warp threads and in the tubular edge area the two weft threads being set apart from one another and being bound with respective discrete warp threads to form the two superposed woven layers, the tape being characterized in that in the tubular edge area at least one of the weft threads bound with the group of warp threads of one of the two superposed woven layers is passed, according to a preselected sequential order, to become bound with at least one warp thread belonging to the group of warp threads of the other layer thus forming the closure of the tubular edge.

2. A tape according to Claim 1, characterized in that either of the two woven layers of the tubular edge is entirely formed with either of the two weft threads and with a group of warp threads and the other layer is formed entirely with the other weft thread and with a second group of warp threads, the weft thread forming either layer being bound to every pick also with at least one warp thread belonging to the group of the other of the two layers.

3. A tape according to Claim 2, characterized in that said at least one warp thread, belonging to the group of the other of the two layers, with which said weft thread is bound, is composed of the last warp thread of said group, away of the common warp thread group forming the single woven fabric area.

4. A tape according to Claim 2, characterized in that said at least one warp thread, belonging to the group of the other of the two layers, with which said weft thread is bound, is composed of a warp thread adjacent to the group of warp threads in common which forms the single woven layer area.

5. A tape according to Claim 1, characterized in that the two superposed woven layers of the tubular edge are formed, according to a preselected sequential order, both by the one and the other of the two weft threads in coaction with two discrete groups of warp threads and in that the portions of the weft threads in the transition from the binding with a warp thread of one group to the binding with a warp thread of the other group form the closure of the tubular edge.

Drawing