Method and device for producing a tubular knitted textile structure

7y Holder (s): MDB TEXINOV Simplified joint stock company, DELTAVAL Limited liability company.

© Agent (s): CABINET LAURENT ET CHARRAS.

-1PROCEDE AND DEVICE FOR THE REALIZATION OF A TEXTILE STRUCTURE

TUBULAR KNITTED

Field of the invention

The present invention falls within the field of the production of tubular textile structures, produced by knitting, using the so-called “jetted stitch” technology. It also relates to a device implementing this method.

Prior state of the art

The need for tubular textile structures has existed for a long time already, and moreover, is proving to be constantly increasing, in particular in the fields of circulation of fluids whatever they may be.

Traditionally, most of the tubular textile structures that exist today are produced on braiding or braiding looms. Such braids have the advantage of having a certain cohesion and high mechanical strength.

The textiles obtained, by the diagonal arrangement of the threads, have a certain extensibility and a diameter which is not perfectly defined.

This diameter is, in addition, determined by that of the trade. The change in diameter makes it necessary to choose another machine, without allowing intermediate adjustments to be made.

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

It is also known to produce tubular textile structures on cell-picked mesh looms or on hook looms.

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

-2 In addition, the braiding technique imposes a choice of constituents of materials of the same nature, thereby limiting the possible combinations, and consequently, the applications likely to result from such tubular structures.

The objective sought by the present invention is to allow the production of such a tubular textile structure developing a controlled extensibility of its diameter, therefore in the radial direction, and moreover capable of developing mechanical properties impossible to achieve with the techniques of prior art.

DISCLOSURE OF THE INVENTION

To this end, the invention provides a method for producing a tubular knitted textile structure which consists of:

first of all to be produced by throw-stitch knitting on a double needle bed loom, two webs joined together to ultimately define a tubular or multi-tubular structure;

and in inserting a continuous weft at the level of the double needle bed, coming to be inserted in the stitches on said two sheets with offset in the production direction, the weft being conveyed at the level of the needle beds by rotation around the latter.

In other words, the method of the invention consists in producing a 3D structure by means of the implementation of a double needle bed knitting machine, typically a Rachel loom, implementing in a known manner the so-called warp knit technology. , then coming to weave by means of a continuous weft the resulting 3D structure, the continuity of the weft thread making it possible in particular to effectively control in particular the resistance 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, the steaming being almost zero.

In fact, due to the insertion of a continuous weft, concomitantly with the knitting on the double needle bed loom, in fact, a continuous helical weft is 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 with respect to the production direction.

-3In addition, this process makes it possible to vary the choice of materials used and in particular to differentiate the constituent threads of the structure obtained on the Rachel double needle bed loom and the weft thread, thus making it possible to multiply the possible applications of the tubular structure and as a corollary its properties, in particular physical or mechanical.

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

According to the invention, the joining of the two layers can take place at their lateral edges, with a view to ultimately forming a tubular structure. But this joining can also take place in an intermediate zone, so as to produce a multi-tubular structure. This joining is carried out using so-called “pile” threads. These are the usual binding threads distributed over one or more bars of a double needle bed loom. These threads pass alternately through the movement of the loom from one needle bed to another to create a textile having a thickness. Those skilled in the art will know how to apply without difficulty the various possible connections in order 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 wire of different count or even of a different nature in order to obtain the appropriate resistance.

By eliminating most of the securing threads of the two layers, that is to say by keeping them threaded only on certain portions of the loom, different configurations are likely to be obtained:

• a regular tube if the connecting threads are only maintained according to the weave on 1 to 3 threads at both ends. ;

• a tube provided with a side tab, or two side tabs when the securing son of the plies are maintained on the lateral areas, which are larger;

• a multitube, if the wires for securing the layers are held in several places along the needle bed.

The invention also relates to the device allowing the production of such a knitted tubular structure in accordance with the aforementioned method.

-4This device includes:

a Rachel double needle bed loom supplied with threads, so as to generate a 3D textile structure, a weft thread supply spool of the 3D structure produced on the Rachel double needle bed machine, said spool being subjected to a rotary movement around the double needle bed, concomitantly with the production of the 3D textile structure, so as to cooperate with the knitting members of the two needle beds.

In other words, the device according to the invention uses a rotary weft machine describing rotations around the double needle bed, in order to insert a weft thread in a helical manner on the 3D structure, continuously.

The nature of the constituent threads of the 3D structure is identical or different from that of the weft thread.

According to a first embodiment of the device of the invention, the weft thread supply spool 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 that in particular by toothed pinion gear on a set of teeth at the outer periphery of the crown.

According to another embodiment of the invention, the weft thread supply spool 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 toothed or rack and pinion belt.

The invention also relates to any tubular knitted textile structure obtained by means of the method and the device in accordance with the invention.

BRIEF DESCRIPTION OF THE FIGURES

The manner in which the invention can be implemented and the advantages which result therefrom will emerge more clearly from the exemplary embodiments which follow, given by way of indication and without limitation in support of the appended figures.

FIG. 1 is a schematic perspective representation illustrating a knitted tubular structure obtained by the method and the device of the invention.

FIG. 2 is a view similar to FIG. 1, in which a variation in the diameter of the tubular structure can be observed.

FIG. 3a is a schematic sectional representation of a tubular structure according to the invention, in this case provided with two lateral tabs.

Figure 3b is a schematic sectional representation of a multitubular structure according to another embodiment of the invention.

FIG. 4 is a top view schematic representation of the principle of the method and of the device of the invention.

FIG. 5 is 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 the device of the invention.

FIG. 6 is a schematic perspective representation of a first embodiment of the device of the invention.

FIG. 7 is a schematic perspective representation of a second embodiment of the device of the invention.

DETAILED DESCRIPTION OF THE INVENTION

There is therefore shown in Figure 1 a tubular knitted textile structure 1 obtained by implementing the method and device of the invention. As indicated, this tubular structure is the result of a 3D 2 structure obtained by the weft stitch technology on a Rachel double needle bed loom, made from binding based on chains combined with sectional wefts or single knit, double knit or other type binding. , depending on the texture and the mechanical performance (strength, elongation) desired, in a known manner.

According to the invention, the tubular structure also comprises a continuous helical frame 3, here shown at a constant pitch 4. Both the pitch and the inclination or obliquity of the weft helix can be programmed to vary along the textile structure as a function of the applications envisaged.

This continuous weft 3 makes it possible 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 an expansion of the diameter of the tube.

-6In addition, and due to the technology used, namely the double needle-bed thrown mesh technology, it is also possible to vary the diameter of said structure along its length (i.e. in production direction). ), typically from a few tenths of a millimeter to a few millimeters,

In addition, Rachel looms can be equipped with different gauges, that is to say, with a greater or lesser number of needles and knitting elements, allowing great variability in the adjustment of performance, but also of permeabilities by the rate of mesh openings.

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 Rachel double needle bed loom and thus making it possible to strengthen its mechanical strength because free from any interruption resulting from the cutting of the weft threads observed in the technologies of the prior art.

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

Thus, the two zones A and C each have a constant diameter, but different, by playing on the binding and the control of the flows of yarns of the 3D structure or of the weft yarn and of their tension. These two zones are connected to each other continuously by zone B. Within the latter, the weft thread is also present but can be programmed with a different "pitch" if necessary.

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.

Figures 3a and 3b illustrate different variants of the tubular structure of the invention. Thus, FIG. 3a illustrates a tubular structure, provided with two lateral tabs 25, 26, resulting from the joining of the two textile faces obtained by the Rachel double needle bed loom. These tongues are capable of constituting reinforced zones suitable for allowing the fixing of the tubular structure according to the applications envisaged.

The continuous weft again traverses the entire circumference of the textile structure, including at these tabs.

FIG. 3b shows another variant, comprising in this case three tubular structures, separated from each other in pairs by a junction zone 27. The production of such a structure is based on the same principle. Here again, the continuous weft yarn traverses the entire circumference of the structure, both at the level of the tubular zones proper and at the junction zones and tongues.

The principle of the process of the invention has been shown in relation to FIG. 4. Basically and as already indicated, a 3D structure is generated using a Rachel double needle bed 5 loom (for which, for the sake of understanding, the wire feed modules have not been shown).

Around this double needle bed loom, turns (arrow G) a supply reel 7 of weft thread 3, mounted on a support 6, 6 '. In fact, the weft thread therefore weaves around the needles and guides mounted on the needle beds of the RACHEL loom as the 3D structure is produced at this level.

For this purpose, the supply spool 7 of weft yarn 3 is arranged in a plane inscribed perpendicularly to that receiving the double needle beds and passing at the level of the area of ​​cooperation of the needles and the guides of said needle beds.

The rotary movement of the coil 7 around the two needle beds is obtained by any means, and in any event, by a mechanism synchronized with the cycle of formation of the stitches on the double needle bed loom. This spool 7 delivers the weft thread 3 after passing through a braking device 8, in order to ensure correct tension of the weft thread. This braking takes place either directly on the weft thread or on the spool itself. Such braking systems are known per se. They may in particular be of a mechanical, electrical or even electromagnetic nature.

The programming of the pitch of the helix resulting from the insertion of this weft yarn 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.

It is in fact possible to program to stop the unwinding of the weft and to leave the latter on hold on one side, then to control it again when desired.

-8This double needle bed has also been shown schematically in top view in FIG. 5. The front 10 and rear 11 needle beds have thus been materialized, at the level of which the knitting threads 9 of the 3D support structure appear, as well as the arrangement diagram of the weft thread 3 inserted by means of the device which is the subject of the present invention.

According to a first embodiment of the invention shown in relation to FIG. 6, the supply spool 7 of weft thread 3 is mounted on a circular ring 15. This circular ring is therefore mounted around the double needle bed 5. It is rotated by means of toothed pinions 16, the axis of rotation 17 of which is actuated by electric motors (not shown). These toothed pinions 16 mesh with the toothed peripheral edge 18 of said crown 15. The management of the electric motor (s) actuating the toothed pinions 16 is synchronized with the operating cycle of the double needle bed loom, so as to introduce the weft thread 3 at the appropriate time at each of the needle beds.

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

This figure also shows the braking device 8 positioned at the outlet of the spool, for the purpose of regulating the tension of the weft thread.

According to another embodiment of the device of the invention shown in FIG. 7, the supply spool 7 of weft yarn 3 is mounted on a carriage 25 guided according to a guide system, in this case, in the form of a racetrack, and typically consisting of rectilinear portions 26 and curvilinear portions 27, suitable for constituting a continuous path for said cart 25, and corollary for the reel 7. In doing so, the carriage 25 also ensures revolutions around the double needle bed loom, like the embodiment described above. To this end, the carriage 25 is integral with 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.

The weft reel support carriage is then released at the rectilinear end of travel 26 to be supported by another means of transport on the crown 27.

-9This embodiment is particularly advantageous for the production of tubular textile structures of large width or large diameter, allowing in particular the use of linear motors or high speed control by appropriate electronics.

The invention also relates to the tubular textile structures obtained by the method and the device described above.