METHOD AND DEVICE FOR PRODUCEING A TUBING KNITTED TEXTILE STRUCTURE

Description

FIELD OF THE INVENTION

[0001] The present invention falls within the field of the production of tubular textile structures, made by knitting, using the so-called "warp knit" technology. It also relates to a device implementing this method. PRIOR STATE OF THE ART

[0002] The need for tubular textile structures has existed for a long time and is constantly increasing, particularly in the areas of circulation of all fluids.

[0003] Traditionally, most tubular textile structures that exist today are made on braiding machines or braiders. Such braids have the advantage of having a certain cohesion and significant mechanical resistance.

[0004] The textiles obtained, due to the diagonal arrangement of the threads, have a certain extensibility and a diameter that is not perfectly defined.

[0005] This diameter is, in addition, determined by that of the trade. Changing the diameter requires choosing another machine, without allowing for intermediate adjustments.

[0006] Furthermore, it is practically not possible to combine different materials for the construction of the tubular textiles in question.

[0007] We also know how to make tubular textile structures on cellular gathered mesh looms or on crochet looms.

[0008] Regardless of the techniques used, the diameter of the resulting tubular structure is only approximately controlled, and moreover, there is always a greater or lesser possibility of radial extension of the said structure. In addition, the mechanical properties always remain limited along this radial direction.

[0009] In addition, the braiding technique requires a choice of constituent materials of the same nature, thereby limiting the possible combinations and, consequently, the applications likely to result from such tubular structures.

[0010] US 3606770 describes prior art tubular knitted textile structures and methods of manufacturing them, and EP 0450068 describes a device for inserting prior art wefts.

[0011] The objective sought by the present invention is to enable the production of such a tubular textile structure developing a controlled extensibility of its diameter, therefore in the radial direction, and capable furthermore of developing mechanical properties impossible to achieve with the techniques of the prior art. STATEMENT OF THE INVENTION

[0012] To this end, the invention proposes a method for producing a tubular knitted textile structure according to claim 1 which consists of: first of all to produce by warp knitting on a double-bed loom two layers joined together to ultimately define a tubular or multi-tubular structure; and to insert a continuous weft at the double bed, which is inserted into the stitches on said two layers with offset in the production direction, the weft being conveyed to the beds by rotation around the latter.

[0013] In other words, the method of the invention consists of producing a 3D structure using a double-bed knitting machine, typically a Rachel machine, implementing in a known manner the so-called warp stitch technology, then weaving the resulting 3D structure using a continuous weft, the continuity of the weft yarn making it possible in particular to effectively control the strength and elongation properties of the tubular structure. The properties are thus directly identical or in any case very close to the characteristics of the weft yarn, with the weft being almost zero.

[0014] In fact, due to the insertion of a continuous weft, concomitantly with knitting on the double-bed loom, a continuous helical weft is actually generated at the level of the tubular or multi-tubular structure, the pitch of which, of course, can be variable and adjusted to the desired performance, and which makes it possible to block and limit the circumference of the textile structure in the transverse direction compared to the production direction.

[0015] In addition, this process makes it possible to vary the choice of materials used and in particular to differentiate the threads constituting the structure obtained on the double-bed Rachel loom and the weft thread, thus making it possible to multiply the possible applications of the tubular structure and, consequently, its properties, particularly physical or mechanical.

[0016] Finally, the method of the invention makes it possible to obtain a tubular structure whose mechanical properties are controlled in two directions.

[0017] By multi-tubular structure is meant the production of structures having not one but several tubes extending substantially parallel to each other, said tubes being capable of being separated from each other after their production.

[0018] According to the invention, the joining of the two plies can take place at their lateral edges, with a view to eventually forming a tubular structure. But this joining can also take place in the intermediate zone, so as to create a multi-tubular structure. This joining is carried out using threads called in the field considered by "pile threads". These are the usual connecting threads distributed on a single or on several bars of a double-bed loom. These threads pass alternately through the movement of the loom from one bed to the other to create a textile having a thickness. The person skilled in the art will know without difficulty how to apply the different possible connections to stiffen this connection as required and possibly keep it completely homogeneous with the weave of each of the two faces. It is also possible to choose a thread of different count or even of different nature in order to obtain the appropriate resistance.

[0019] By eliminating most of the threads holding the two layers together, that is to say by only keeping them threaded on certain portions of the loom, we are likely to obtain different configurations: a regular tube if the connecting threads are only held according to the weave on 1 to 3 threads at both ends; a tube fitted with a side tab, or two side tabs when the threads securing the plies are held on larger lateral areas; a multi-tube, if the threads securing the plies are held in several places along the needle bed.

[0020] The invention also relates to devices allowing the production of such a knitted tubular structure in accordance with the aforementioned method, according to claims 8 and 9.

[0021] These devices include: a double-bed Rachel loom supplied with threads, so as to generate a 3D textile structure, a reel for supplying the 3D structure with weft thread produced on the double-bed Rachel loom, said reel being subjected to a rotary movement around the double bed, concomitantly with the production of the 3D textile structure, so as to cooperate with the knitting members of the two beds.

[0022] In other words, the device according to the invention uses a rotary wefter describing rotations around the double needle bed, in order to insert a weft thread in a helix onto the 3D structure, continuously.

[0023] The nature of the threads constituting the 3D structure is identical or different from that of the weft thread.

[0024] According to a first embodiment of the device of the invention, the weft yarn supply reel is mounted on a circular crown in the center of which the double needle bed is mounted, the circular crown being rotated by any means, such as in particular by gearing with toothed pinions on a toothing arranged on the external periphery of the crown.

[0025] According to another embodiment of the invention, the weft yarn supply reel is mounted on a carriage guided on guide means surrounding the double needle bed, said carriage being moved on said guide means by any means such as a toothed belt or rack and pinions.

[0026] The invention also relates to any tubular knitted textile structure obtained by means of the process in accordance with the invention. BRIEF DESCRIPTION OF THE FIGURES

[0027] The manner in which the invention can be implemented and the advantages which result therefrom will become more apparent from the following examples of implementation, given for informational and non-limiting purposes in support of the appended figures. There figure 1 is a schematic perspective representation illustrating a knitted tubular structure obtained by the method and device of the invention. The figure 2 is a view analogous to the figure 1 , in which a variation in the diameter of the tubular structure can be observed. The Figure 3a is a schematic representation in section of a tubular structure according to the invention, in this case provided with two lateral tabs. The Figure 3b is a schematic sectional representation of a multi-tubular structure according to another embodiment of the invention. The figure 4 is a schematic representation seen from above of the principle of the method and device of the invention. The Figure 5is a schematic representation seen from above of a double needle bed with representation of the circular and continuous weft thread in accordance with the method and device of the invention. The figure 6 is a schematic perspective representation of a first embodiment of the device of the invention. The figure 7 is a schematic perspective representation of a second embodiment of the device of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] We have therefore represented within the figure 1 a knitted textile tubular structure 1 obtained by implementing the method and device of the invention. As indicated, this tubular structure results from a 3D structure 2obtained by warp stitch technology on a double-bed Rachel loom, made from a binding based on chains combined with sectional wefts or simple knitting, double knitting or other type binding, depending on the texture and mechanical performance (resistance, elongation) desired, and this, in a known manner.

[0029] According to the invention, the tubular structure also comprises a continuous helical frame 3, here represented according to a step 4 constant. Both the pitch and the inclination or obliquity of the weft helix can be programmed to vary along the textile structure depending on the intended applications.

[0030] This plot continues 3 allows to limit, or even prohibit, depending on the nature of the wire which constitutes it, any extensibility of the structure in the radial direction, that is to say any expansion of the diameter of the tube.

[0031] Moreover, and due to the technology implemented, namely the double-bed warp stitch technology, it is also possible to vary the diameter of said structure along its length (i.e. in the production direction), typically from a few tenths of a millimeter to a few millimeters.

[0032] Furthermore, Rachel looms can be equipped with different gauges, that is to say, with a greater or lesser number of needles and knitting elements, allowing a great variability in performance adjustment, but also permeabilities through the rate of opening of the stitches.

[0033] One of the essential elements of the invention lies in the continuous nature of the weft thread, which is therefore inserted over the entire circumference of the 3D textile structure manufactured on the double-bed type Rachel loom and thus making it possible to reinforce its mechanical resistance because it is free from any interruption resulting from the cutting of the weft threads observed in the technologies of the prior art.

[0034] The variability of diameter has been illustrated within the figure 2 , in which three distinct zones A, B and C, of ​​respective programmable length, have been represented.

[0035] Thus, the two zones A and C each have a constant, but different diameter, by playing on the binding and the control of the flow rates of the 3D structure threads or the weft thread and their tension. These two zones are continuously linked together by zone B. Within the latter, the weft thread is also present but can be programmed with a different "pitch" if necessary.

[0036] Furthermore, the pitch of the helix formed by the weft thread 3 can vary from zone A to zone C, so as to give these two zones different properties, mechanical for example.

[0037] THE Figures 3a and 3b illustrate different variants of the tubular structure of the invention. Thus, the Figure 3a illustrates a tubular structure, equipped with two side tabs 25, 26,resulting from the joining of the two textile faces obtained by the double-bed Rachel loom. These tabs are likely to constitute reinforced zones suitable for allowing the tubular structure to be fixed depending on the intended applications.

[0038] The continuous weft again runs around the entire circumference of the textile structure, including at the level of these tabs.

[0039] We have represented within the Figure 3b another variant, comprising in this case three tubular structures, separated from each other two by two by a junction zone 27. The construction of such a structure is based on the same principle. Here again, the continuous weft thread runs around the entire circumference of the structure, both in the tubular areas themselves and in the junction and tongue areas.

[0040] It has been represented in relation to the figure 4the principle of the method of the invention. Basically and as already indicated, a 3D structure is generated using a double-bed Rachel loom 5 (for which, for the sake of simplification of understanding, the wire feed modules have not been shown).

[0041] Around this double-bed loom, a supply reel 7 of weft thread rotates (arrow G) 3, mounted on a support 6, 6'. In fact, the weft thread is therefore wefted at the level of the needles and guides mounted on the needle beds of the RACHEL loom as the 3D structure is created at this level.

[0042] For this purpose, the supply coil 7 in weft thread 3 is arranged in a plane perpendicular to that receiving the double needle beds and passing at the level of the cooperation zone of the needles and the guides of said needle beds.

[0043] The rotary motion of the coil 7 around the two needle beds is obtained by any means, and in any case, by a mechanism synchronized with the cycle of formation of the stitches on the double needle bed loom. This bobbin 7 delivers the weft thread 3 after passing through a braking device 8, to ensure correct tension of the weft thread. This braking is carried out either directly on the weft thread or on the bobbin itself. Such braking systems are known in themselves. They can be mechanical, electrical or even electromagnetic in nature.

[0044] The programming of the helix pitch resulting from the insertion of this weft thread can in particular be a direct consequence of the sequences for introducing the weft in question into the knitting program of the 3D background structure.

[0045] In fact, it is possible to program to stop the unfolding of the frame and leave it waiting on one side, then control it again when desired.

[0046] This double needle bed has also been shown schematically in top view on the Figure 5 . We thus materialized the front beds 10 and back 11, at which the knitting threads appear 9 of the 3D support structure, as well as the schematic arrangement of the weft thread 3 inserted by means of the device which is the subject of the present invention.

[0047] According to a first embodiment of the invention shown in relation to the figure 6 , the power supply coil 7 in weft thread 3 is mounted on a circular crown 15. This circular crown is therefore mounted around the double-bed loom 5. It is rotated by means of toothed pinions16 whose axis of rotation 17 powered by electric motors (not shown). These toothed pinions 16 mesh with the toothed peripheral edge 18 of the said crown 15. Management of the electric motor(s) operating the toothed pinions 16 is synchronized with the operating cycle of the double-bed loom, so as to introduce the weft thread 3 at the appropriate time at each of the needle beds.

[0048] So, the weft thread 3 performs a revolution, and in the example described a rotation, around the needle beds in the area where the 3D textile structure obtained by the play of knitting members mounted on needle beds, respectively needles, is produced 20 and passers 21. The guides themselves are moved on support bars 22, according to the selected thread binding program.

[0049] The braking device is also shown in this figure. 8 positioned at the exit of the bobbin, for the purpose of regulating the tension of the weft thread.

[0050] According to another embodiment of the device of the invention shown in the figure 7 , the power supply coil 7 in weft thread 3 is mounted on a cart 25 guided by a guidance system, in this case, in the form of a racetrack, and typically made up of rectilinear portions 26 and curvilinear portions 27, suitable for constituting a continuous path for the said cart 25, and corollarily for coil 7. In doing so, the carriage 25 also ensures revolutions around the double-bed loom, like the previously described method. For this purpose, the carriage 25is secured to a toothed belt or any other equivalent device, cooperating with a suitable roller (not shown), or any other means capable of ensuring its progression on the guide path 26, 27.

[0051] The weft reel support carriage is then released at the end of its rectilinear travel. 26 to be picked up by another means of transport on the crown 27.

[0052] This embodiment is particularly advantageous for the production of tubular textile structures of great width or large diameter, allowing in particular the use of linear motors or high-speed control by appropriate electronics.

[0053] The invention also relates to the tubular textile structures obtained by the process described above.

Claims

1. Method for producing a tubular knitted textile structure (1), consisting in: - firstly producing, by warp knitting with a stitch on a double needle bed Rachel loom (5), two plies joined together by connecting threads which pass alternately through the movement of the loom from one needle bed to the other in order to create a textile having a thickness, constituting a 3D structure (2) in order ultimately to define a tubular or multi-tubular structure, namely a structure having several tubes substantially parallel to one another, said tubes being capable of being separated from one another after they have been produced; - and inserting a continuous weft (3) at the double needle bed, which is inserted into the stitches on said two plies with an offset in the direction of production, the continuous weft being conveyed at the needle beds by revolution around the needle beds.

2. Method for producing a tubular knitted textile structure (1) according to claim 1, characterised in that the two plies are joined together, in order to forming over time a tubular or multi-tubular structure, by means of connecting threads intervening at intermediate points.

3. Method for producing a tubular knitted textile structure (1) according to any one of claims 1 and 2, characterised in that the weft (3) is inserted within the 3D structure in a helical manner with respect to the production direction of said structure.

4. Method for producing a tubular knitted textile structure (1) according to claim 3, characterised in that the pitch (4) of the helix is constant.

5. Method for producing a tubular knitted textile structure (1) according to claim 3, characterised in that the pitch (4) of the helix is configurable, and is liable to vary during the production of the textile structure.

6. Method for producing a tubular knitted textile structure (1) according to any one of claims 1 to 5, characterised in that the nature of the constituent yarns of the 3D structure (2) is identical to or different from that of the weft yarn (3).

7. Knitted tubular textile structure (1) obtained according to the method of any one of claims 1 to 6.

8. Device for producing a tubular knitted textile structure (1) according to claim 7, comprising: - a double needle bed Rachel loom (5) fed with yarns (9), so as to generate a 3D textile structure (2), - a supply reel (7) of weft yarn (3) of the 3D structure produced on the double needle bed Rachel loom, said reel being subjected to a revolution-type movement around the double needle bed loom (5), concomitantly with the production of the 3D textile structure, so as to cooperate with the knitting members (20, 21) of the two needle beds, said reel (7) being mounted on a circular crown (15) at the centre of which the double needle bed loom (5) is mounted, the circular crown (15) being rotated by any means, such as in particular by gearing with toothed pinions (16) meshing on a toothing (18) arranged at the external periphery of the crown.

9. Device for producing a tubular knitted textile structure (1) according to claim 7, comprising: - a double needle bed Rachel loom (5) fed with yarns (9), so as to generate a 3D textile structure (2), - a supply reel (7) of weft yarn (3) of the 3D structure produced on the double needle bed Rachel loom, said reel being subjected to a revolution-type movement around the double needle bed loom (5), concomitantly with the production of the 3D textile structure, so as to cooperate with the knitting members (20, 21) of the two needle beds, said reel (7) being mounted on a carriage (25) guided on a guide path (26, 27) surrounding the double needle bed loom (5), said carriage being moved on said guide path by any means such as a toothed belt or rack and pinions.