Knitted fabric with edge reinforcement and device and method for producing such a knitted fabric

Description

[0001] The invention relates to a knitted fabric with edge reinforcement, a device, and a method for its production. Knitted fabrics with a weft thread system are known. In a knitted fabric, a knit, also referred to as a warp-knitted fabric, is produced using a loop-forming warp thread system. In principle, a knit fabric is stable enough even without a weft thread and has a corresponding cohesion because the loops are connected to one another not only in the longitudinal but also in the transverse direction of a web. For aesthetic and strength reasons, however, weft threads can also be inserted into knitted fabrics that have an even distribution of loops across the entire width. These weft threads are tied off in the loops by loop-forming elements. Knitted fabrics are also frequently used as a lattice structure.In such a lattice structure, the warp threads forming the loops are used in the direction of fabric production to create strips consisting of multiple, widthwise and interwoven loops. These strips are interconnected in the widthwise direction by weft threads integrated into the loops. Weft threads are essential for this lattice fabric. In particular, the lattice structure underlying the invention requires three types of thread: loop-forming warp threads, stay threads, and weft threads. In contrast to a knitted fabric, weft threads that undulate with the warp threads are always required for woven fabrics.

[0002] To impart appropriate edge stability to the knitted fabric, various measures have become known in the prior art. DE 10 163 730 C1 describes a method and a warp knitting machine for producing a warp-knitted fabric with inserted reinforcing elements. The described reinforcing elements serve to increase the strength of the knitted fabric and consist of thread, fiber, fleece, or other elements oriented in the warp direction. These reinforcing elements are introduced in such a way that they reinforce the stitch structure, which requires a more complex needle structure and thus a more complex knitting element arrangement. The reinforcing elements are inserted within the fabric web, but not at the edge areas to reinforce the knitted fabric.

[0003] DE 10 021 341 A1 describes a method and a device for forming, primarily, multi-layered weft thread layings with multiaxially oriented thread scrims, as well as a thread layer for this purpose. Continuous weft threads are laid in the forward direction and then back in the return direction, with all weft threads being the same distance apart, regardless of the laying direction. Particular attention was paid to thread-protecting thread reversal. The knitted fabric is reinforced overall by the continuous weft threads; a requirement for a soft and flowing knitted fabric with simultaneous edge reinforcement is not addressed in this document.

[0004] Although CN 111 479 964 A describes a lattice structure of a knitted fabric in which longitudinal and transverse threads are tied at their respective intersection points, this prior art does not contain any information on reinforcing the edge areas of the knitted fabric or the warp-knitted fabric, apart from a multi-layered covering layer with reinforcements.

[0005] US Pat. No. 5,246,306 B describes reinforcements for asphalt layers, methods for producing such reinforcements, and reinforced layers. A grid structure is placed on such an asphalt layer, and intersecting fibers are fixed at their intersection points. Edge reinforcements are not described.

[0006] DE 10 2006 003 413 B3 describes a fabric with a tucked-in edge formed by inserted weft thread end sections and a use for the same. In the fabric described, monofilament weft threads of finite length, which is wider than the actual fabric width, are tied off in a crisscrossing manner in the direction of fabric production, and their protruding ends are folded over by 180° and woven into the side areas. This creates tucked-in edges which, however, have nothing to do with stabilizing the edge areas of the fabric, but rather serve to create a field with alphanumeric characters, logos or at least a color, which is intended as an advertising medium in the edge area of ​​the fabric. The tucked-in edge therefore has a purely optical or aesthetic purpose and is used primarily for the presentation of labels for particularly high-priced ready-made clothing.

[0007] Furthermore, CH 688 382 A5 describes a process for sharply defined inset selvedges, particularly for Arab headscarves. The fabric edge is also used as an aesthetic feature; the weft threads are undulated in the usual way in a crisscrossing manner, depending on the weave with the warp threads. This involves tying them off, whereby an end of the respective weft thread that extends beyond the fabric width is folded over 180° and woven into the edges. This, too, is not edge reinforcement, but a purely aesthetic feature.

[0008] DE 4 222 076 A1 also describes a fabric in which, by means of an inlay technique, a protruding end of a weft thread is inserted into the edge area of ​​the fabric by means of a 180° fold, the aim being to bind the weft thread ends in the fabric in such a way that they are ultimately essentially invisible.

[0009] Known knitted fabrics stabilized with reinforcements are limited to the use of reinforcements for the knitted fabric, either across the surface or in the interior; reinforcements in the edge area, however, are not described. The tucked-in edges described for woven fabrics have nothing to do with knitted fabrics and can only be achieved by folding over protruding weft threads by 180°, since the weaving process, due to the beating of the weft threads at the binding point, leaves no other options. Thus, with tucked-in edges of woven fabrics, there is only one defined orientation of the tucked-in weft thread end, regardless of whether the weft threads are multifilament or monofilament.The familiar fabrics with tucked-in edges are based on the idea of ​​making a virtue out of necessity by not cutting off the weft thread ends, which would result in unsightly fraying, but rather weaving and concealing the weft thread ends to increase overall visual appeal. With knitted fabrics, particularly grid-like geotextiles, the situation is completely different—and not comparable to woven fabrics. Examples of knitted fabrics with weft threads can also be found in documents DE 91 08 299 U1, DE 15 85 404 B1, DE 196 07 182 A1, and US 3 874 201 A.

[0010] Compared to known textiles, the object of the invention is therefore to create a textile grid consisting of weft threads, standing threads and loop-forming warp threads, wherein the weft threads are finite weft threads and their ends projecting beyond the width of the knitted fabric are preferably woven back in an uncontrolled manner, i.e. in any angular arrangement, diagonally opposite to the direction of web production. This object includes the use of not only monofilament but also multifilament yarns as weft threads, in which a fanning out of the individual filaments results in the weft thread ends being laid back into the knitted fabric as tucked-in edges not at one angle but at a multitude of different angles for individual filaments of the multifilament yarn of the weft thread, where they are incorporated into the loops and fixed.

[0011] This object is achieved by a knitted fabric having the features according to claim 1, a device having the features according to claim 7, and a method having the features according to claim 9. Appropriate further developments are defined in the respective dependent claims.

[0012] The knitted fabric according to the invention has a loop-forming warp thread system into which finite weft threads are incorporated, i.e. knitted in. The knitted fabric is designed as a web of material with a defined width, with a standing thread arranged at its edges, which delimits the web of material at the edges. The knitted-in finite weft threads have a length which is greater than the width of the web of material, so that they have an overhang with respect to the respective standing thread. In order to achieve edge reinforcement, a tucked-in edge of the knitted fabric is formed by deflecting the overhang of the weft thread relative to the web width at a defined angle opposite to the web production direction. The overhang is deflected at least far enough that it is tied off as a tucked-in edge in the loop-forming warp thread system in at least one stitch of the stitches following in the direction of fabric production.Weft threads are used in knitted fabrics as monofilament or multifilament threads. The advantage over all the known tucked-in edges for woven fabrics is that the excess length does not have to be folded over at a defined angle against the direction of fabric production. Rather, it is sufficient if the excess length of the weft thread is folded over in any direction, preferably between 90° and 180°. Edge strengthening already occurs when the excess length has been woven in again by folding it over against the direction of fabric production, i.e. in the direction of the standing threads. Compared to monofilament weft yarns, multifilament weft yarns have the problem that the folding can cause the individual filaments of the thread to fan out to a certain extent. If such excess lengths are folded over from multifilament yarns in a fanned out manner, the individual filaments orGroups of filaments are knitted into different stitches and thus bound together. This binding of individual filaments or individual groups of filaments has the advantage that individual filaments do not protrude from the knitted fabric and, on the other hand, allows for a fairly good edge reinforcement of the knitted fabric.

[0013] In principle, it is sufficient for the excess material folded back against the direction of fabric production in the stitches following the actual weft thread to be tied off in at least one of these stitches. However, it is preferable for the excess material to be tied off multiple times, i.e., in several stitches. If multiple binding is used, better edge reinforcement of the knitted fabric can generally be achieved than if the excess material is tied off in only a single stitch.

[0014] According to the invention, the knitted fabric is preferably a textile grid. Such a textile grid consists of three thread systems: the standing threads, which run continuously in the production direction without any change in direction, i.e. in a so-called 0° direction; the weft threads, which run transversely to the production direction of the fabric web, i.e. in a 90° direction, whereby the weft threads and the standing threads taken alone do cross but do not yet form a fabric web in which the two threads are connected; and warp threads, by means of which the stitches are formed. These stitches are shaped and arranged in such a way that they fix the standing threads and the weft threads relative to one another, in particular at their crossing points. If necessary, the standing threads are also fixed; the standing threads and the weft threads can preferably be fixed relative to one another in groups.If one of these thread systems were missing, the fabric webs would disintegrate into individual pieces, which would then no longer constitute a functioning textile mesh. The system known as the loop-forming warp thread system comprises the warp threads, which are simultaneously drawn off a respective warp beam and, with loop-forming needle systems, create the interconnected loops and thus the knitted fabric.

[0015] A significant advantage of the present invention is that when integrating the excess weft threads into the knitted fabric edge, i.e., the stitches present there, the excess can be incorporated without particular consideration of the exact position of the excess with respect to the fabric production direction or the stitch formation direction. The relatively high filament counts of weft threads typically used in textile mesh structures, especially geotextile meshes, contribute to a significant edge reinforcement of the knitted fabric, even if the excess is folded over and thus incorporated into a multitude of stitches.

[0016] Preferably, the overhang of the weft threads is folded in such a way that at the edge of the fabric, an alignment of approximately 0°, i.e. in the direction of the respective lateral standing thread, takes place, at least over the length of a stitch, so that for weaving or binding this one stitch remains virtually free and only then is the overhang swung back into the subsequent stitch, so that only then is the overhang aligned against the direction of fabric production at any desired, uncontrolled angle and thus woven.

[0017] This uncontrolled insertion means that the angular alignment of the excess length in the tucked-in edge is not controlled, so that all excess lengths, for example, would have the same angle to the fabric web production direction. Instead, a simple fold-over is implemented. The only important thing is that the folded portion, i.e., the excess length of the weft thread, is appropriately incorporated and thus fixed in at least one stitch, preferably in several stitches. This creates edge reinforcement of the knitted fabric.

[0018] Preferably, the knitted fabric has a grid structure in which the rows of stitches running in the direction of fabric production across the fabric width have regions between such rows of stitches in which only weft threads are present, connecting the individual rows of stitches to one another, thus creating an overall grid structure. The excess weft threads are then expediently knitted into at least one stitch in each of the rows of stitches present at the edges of the knitted fabric.

[0019] According to a further aspect of the invention, the device for producing knitted fabric according to the above-mentioned features of the knitted fabric according to the invention is constructed such that corresponding knitting tools are provided for a loop-forming warp thread system and a weft thread insertion system for inserting weft threads into the loop-forming warp thread system, so that the weft threads in the loop-forming warp thread system are correspondingly tied off in respective loops thereof. The weft threads, which have a length which extends beyond the width of the knitted fabric web, form an overhang compared to the width of the knitted fabric. According to the device according to the invention, this overhang is reinserted from the outside, i.e. viewed from the outer standing thread, back into the outer warp thread rows, which consist of loops, by means of a deflection element.The edge-strengthening tucked-in edge is formed by reinserting the excess material into the corresponding stitch rows formed by the warp thread system. The orientation of the excess material in the tucked-in edge is arbitrary, uncontrolled, or uncontrolled.

[0020] The deflection element is preferably designed as an air jet arrangement, i.e., a pneumatic arrangement. However, it is also possible to use mechanical deflection elements, such as mechanical guides, a sliding shoe or strip arrangement, or a brush, comb, or rake arrangement. The use of a particular deflection element also depends on the type of material of the weft threads used. An air jet arrangement as a pneumatic arrangement is preferred.

[0021] According to a further aspect of the invention, a previously described edge-bonded knitted fabric is produced using a previously described device. In the method according to the invention, finite weft threads are inserted into a loop-forming warp thread system forming a fabric web. The fabric web is delimited at its fabric edges by stay threads. The ends of the weft threads, which extend beyond the width of the fabric web, serve to strengthen the edge of the knitted fabric, so that the weft threads are longer than the width of the fabric web. These excess lengths relative to the fabric edges are inserted against the fabric web production direction, first along the edge stay threads and then back into at least the outer rows of the stitches formed by the loop-forming warp thread system.According to the invention, the excess length is inserted into at least one stitch of the rows of stitches located at the fabric edges at an angle to the weft thread direction to form an edge-strengthening tucked-in edge. The method is principally directed at monofilament weft threads as well as multifilament weft threads. Preferably, the excess length of the weft threads is inserted into the stitch-forming warp thread system in an uncontrolled manner with regard to their insertion direction. This means that when using monofilament weft threads, the direction of the ends of the weft threads, i.e. their excess length, can be incorporated into the knitted fabric in any direction within an angular range of 90° to 180°.

[0022] With multifilament yarns, it is often unavoidable that cut ends, in this case the excess weft threads, spread out fan-like as a result of the folding process. As a result, the inserted ends are not inserted into the tucked-in edge at a specific angle, but rather over an angular range of individual filaments or individual groups of filaments from the multifilament yarn of the weft threads. The more the fiber ends of the multifilament yarns fan out, the more stitches contribute to binding off the excess weft threads. This creates a tucked-in edge of the knitted fabric that is irregular with respect to the excess weft threads, but which, particularly due to the fanning out, contributes to a significant edge reinforcement of the knitted fabric.

[0023] Preferably, the excess is tied off several times from the outset into the stitches of the stitch-forming warp thread systems in the stitch rows following the weft thread in the direction of fabric production.

[0024] Further advantages and details of the present invention will now be explained in detail with reference to the following drawings for two exemplary embodiments. The drawings show: Figure 1 shows a first embodiment of a knitted fabric in the form of a grid structure according to the invention; and Figure 2 shows a further embodiment of a stitch-forming warp thread system according to the invention in the form of a counter-trimmed tricot lay.

[0025] The Figure 1 The knitted fabric 1 shown represents a grid structure 11. This grid structure is formed by a loop-forming warp thread system 2, standing threads 6 running in the direction of the loop-forming warp thread system and transverse to the loop-forming warp thread rows, which form the Figure 1 vertical structures shown, and weft threads 3 connecting the stitch-forming warp thread rows. The weft threads 3 and the Figure 1The standing threads 6 anchored vertically within the stitch-forming warp thread rows 2 are not connected to one another, i.e., they are not fixed in position. By means of the warp thread system 2 forming the warp thread rows with the stitches 9, the weft threads 3 and the standing threads 6 are fixed in the stitches 9. Only in this way is a position-fixed and durable lattice structure 11 created.

[0026] In the Figure 1The weft threads 3 drawn horizontally are weft threads 3 which are longer than the width of the knitted fabric 1 or the material web 4. This creates an overhang 7 compared to the standing threads 6 located directly at the edge on each side of the material web 4. This overhang 7 is formed by the weft threads 3 being fixed after they have been laid and incorporated into the stitches 9 of the stitch rows 12, so that the grid structure 11 can be used, for example, as a geotextile. However, it is possible that the weft threads 3 can be pulled out of the grid structure 11 again if appropriate tension is applied. This can cause the grid structure 11 to distort in its basic shape of forming rectangular fields and sections.When the textile grid structure 11 is used, for example, as a geotextile in sloping terrain sections, which is the actual function of such geotextiles, namely to prevent the geological layers from slipping or to reduce the tendency for this to happen, this function cannot be fully guaranteed. According to the invention, the overhangs 7 of the respective weft threads 3 are therefore guided back in an uncontrolled manner with respect to the angle against the direction of product production 8 at an angle between 90° and 180° and are also tied off by subsequent stitches which have incorporated the weft threads. This creates a consolidated edge which fixes the weft threads 3, standing threads 6 and stitch rows 12 to one another in such a way that the aligned grid structure 11 remains fixed in its shape even when tensile force is applied to the edges, which can occur, for example, when laying the geotextiles.By reinserting the excess lengths 7 and tying them off in the stitches 9 following the stitches tying off the weft threads 3, a reinforced tucked-in edge 10 is created in the knitted fabric 1 according to the invention. It is relatively unimportant at what angle the excess lengths 7 are tied off in the following stitches 9. To return the respective excess length 7 of the respective weft threads to the outermost stitch row or rows, the excess lengths 7 are tied off in at least one stitch 9 of such a stitch row 12.

[0027] In the Figure 1In the embodiment shown, the overhangs 7 are tied off by two adjacent rows of stitches 12 with the respective stay threads 6, which offers even better hold, even better fixation and even better edge reinforcement. Before reinserting and binding the overhang 7 with the stitches 9, the overhang 7 is tied off at least over the length of a stitch 9 tying off the outer edge stay thread 6 with a 90° deflection with respect to the weft thread direction, ie alignment in the direction of the stay thread 6, and then inserted into the row of stitches 12 or into the rows of stitches with its immediate end in the inserted edge 10. The deflection of the overhang 7 from the in Figure 1shown horizontal direction, which means an alignment to the web production direction 8, i.e. at 90°, by a further 90°, means that the excess lengths 7 initially run along the standing thread 6 arranged at the outermost edge 5, in order to then also counter to the web production direction 8 the remaining excess length 7 of the weft thread 3 is returned in an angled manner into the stitch rows 12. There they are again captured and integrated by the stitch formation. As a result, the respective outer standing threads 6 can no longer be pulled out of the web 4 or displaced within the web 4 by certain process forces transverse to the web 4, for example during further processing or when laying the web 4.

[0028] Thus, an edge-fixed knitted fabric 1 is produced by simple means, which maintains the position of the individual thread structures relative to one another even under difficult geological conditions of use.

[0029] In the embodiment according to Figure 1 Three weft threads 3 are laid in groups, each running at a 90° angle to the fabric web production direction 8. The loop-forming warp threads, which are shown in the loop-forming warp thread rows or in the loop-forming warp thread system 2, bind the weft threads 3 and the standing threads 6 running at a 0° angle to the fabric production direction 8. In Figure 1 This is shown in the form of a fringe arrangement. The warp thread rows or stitch rows 12 are connected to each other via a weft thread system running diagonally in the plane of the fabric web. The overhang 7 of the weft threads 3 is in the example according to Figure 1After being laid back and inserted into the stitch rows 12, the third stitch row following the weft fixation is tied off several times, in the example shown here three times in the corresponding stitches. It is understood that the edge reinforcement takes place on both edges 5 of the fabric web.

[0030] The Figure 2 The illustrated embodiment corresponds to the basic structure of the Figure 1 , so only a specific detail is shown here. In Figure 2 only one standing thread 6 is shown, located at the outermost edge of the web 5, along which its projection 7 is aligned in the 0° direction to the web production direction 8, ie parallel to the outermost standing thread 6, and is captured and bound by the stitches 9 formed there in the stitch-forming warp thread system 2. In the example described according to Figure 2This is a counter-layered tricot lay. Simply tying the excess 7 of the respective weft threads 3 in the direction of the standing threads 6 through the stitches 9 of the stitch-forming warp thread system 2 in the respective outer warp thread rows already achieves a satisfactory binding and thus edge reinforcement and thus positional fixation of the weft threads 3 within the knitted fabric 1.

[0031] The folding of the overhangs 7 of the weft threads for an arrangement according to Figure 1 as well as for an order pursuant to Figure 2is carried out by means of deflection elements (not shown), which are preferably an air nozzle arrangement, i.e. the overhangs 7 are blown into the respective type to be bound in the inserted edge 10. Mechanical deflection elements such as corresponding mechanical guides for the overhangs 7, sliding shoe or sliding strip arrangements or brush, comb or rake arrangements are known to the average person skilled in the art in terms of their basic structure and are therefore not explained further here. It is understood that, depending on the application, the appropriate selection of an application and a corresponding deflection device are required. List of reference symbols

[0032] 1Knitted fabric 2Loop-forming warp thread system 3Weft thread 4Fabric web 5Edge of fabric web 6Staying thread 7Weft thread overhang 8Fabric web production direction 9Stitch 10Inset edge 11Grid structure 12Stitch row

Claims

1. Knitted fabric (1) having a stitch-forming warp-thread system (2) into which weft threads (3) of limited length are incorporated, which knitted fabric (1) is formed as a material web (4) of a defined width at whose edges (5) a filler thread (6) delimiting the material web (4) is arranged in each case, wherein the weft threads (3) have a length which is greater than the width of the material web (4) and have a projection (7) in relation to the respective filler thread (6), characterized in that the projection (7) is deflected by an angle counter to the material-web-production direction (8) at least to the extent as to be tied down as a tucked selvedge (10) in the stitch-forming warp-thread system (2) in at least one stitch (9) of the stitches (9) that follow with regard to the material-web-production direction (8).

2. Knitted fabric (1) according to Claim 1, characterized in that the projection (7) is tied down multiple times as a tucked selvedge (10) in the stitch-forming warp-thread system (2) in the stitches (9) that follow with regard to the material-web-production direction (8).

3. Knitted fabric (1) according to Claim 1 or 2, characterized in that the projection (7) is folded at an angle of 90° to 180°.

4. Knitted fabric (1) according to one of Claims 1 to 3, characterized in that the projection (7) is folded at an angle such that at least one stitch (9) is free between the weft thread (3) and its inlaid projection (7) in the material-production direction (8).

5. Knitted fabric (1) according to one of Claims 1 to 4, characterized in that the folded projections (7) of the respective weft threads (3) are laid in a non-controlled manner into the stitch-forming warp-thread system (2) with regard to their inlay direction.

6. Knitted fabric (1) according to one of Claims 1 to 5, characterized in that the knitted fabric (1) is a mesh structure (11).

7. Device for producing knitted fabric according to Claims 1 to 6, having knitting tools for a stitch-forming warp-thread system (2) and having a weft-thread-inserting system for inserting weft threads (3) into the stitch-forming warp-thread system (2), characterized in that provision is made of a deflecting element for reinserting a weft thread (3) which has a projection (7) beyond a filler thread (6) and which, after being inserted, forms an edge-reinforcing tucked selvedge (10).

8. Device according to Claim 7, characterized in that the deflecting element is in the form of an air-nozzle arrangement, a guide, a sliding-block or strip arrangement, or a brush, comb or rake arrangement.

9. Method for producing an edge-reinforced knitted fabric (1) according to Claims 1 to 6 by means of a device according to Claim 7 or 8, in which weft threads (3) of limited length are inserted into a stitch-forming warp-thread system (2) that forms a material web (4), said material web (4) being delimited by filler threads (6) at the material edges (5), wherein the weft threads (3) are longer than the width of the material web (4) and, by way of their projection (7) in relation to the material edges (5), as a tucked selvedge (10), are laid at an angle to the weft-thread direction into at least one stitch (9), following in the material-production direction, of those rows of stitches (12) of the stitch-forming warp-thread system (2) which are situated at the material edges (5) for the purpose of forming an edge-reinforcing tucked selvedge (10) and are tied down there.

10. Method according to Claim 9, characterized in that the projection (7) of the weft threads (3) projecting beyond the width of the material web (4) is laid in a non-controlled manner into the stitch-forming warp-thread system (2) with regard to its inlay direction.

11. Method according to Claim 9 or 10, characterized in that the projection (7) of the respective weft thread (3) is tied down, in particular multiple times, in rows of stitches (12) which follow the weft thread (3) in relation to the material-production direction (8).