EP0078753B1 - Method of manufacturing elasthane core yarn - Google Patents

Description

The invention relates to a method for manufacturing elastic wrapped yarn with a spandex and more particularly a method for manufacturing simple wrapped elasthane yarn.

It has been well known for a very long time to produce such threads by the technique known as "wrapping", in particular by the technique known as "simple wrapping". To do this, firstly stretching the elastane wire three to five times, then wrapping around it in turns, preferably contiguous, a so-called coating wire, in particular a textured wire. In practice, the number of wrapping turns which varies inversely with the title of the coating wire is of the order of 1000 to 3000 rpm, since it is desired to obtain substantially contiguous turns. Also, when it is desired to make single yarns wrapped as much as possible and with the minimum amount of bulking, such as the yarns that are sought for the manufacture of the bottom legs, fairly thin elasthane yarns are commonly used, this that is to say of the order of 20 to 40 denier, which is covered with a synthetic thread, textured or not of 15 to 30 denier, wrapped at twists of the order of 1500 turns per meter (t / m). In the yarn application for stockings or pantyhose, it is essential that the stretched core elasthane yarn be completely covered by the wrapping yarn, in order to be protected in particular against scuffing.

• - l'impossibilité pratique d'obtenir des enroulements sans noeud dont le poids excède un kilo et ce, d'une part, du fait même du maté- rial de guipage et d'autre part, car au-delà de ce poids, on obtiendrait alors des tensions trop élevées sur le fil enrobant, qui provoqueraient sur le fil guipé fini le défaut dénommé »flash«, en vertu duquel par endroit le fil d'âme n'est pas parfaitement recouvert, ce qui sur les étoffes, provoque des défauts d'aspect et même des faiblesses;
• - un prix de revient élevé, du fait de la consommation électrique appréciable nécessitée par l'entraînement en rotation de la bobine de fil enrobant.

Although this technique is very widely used, it nevertheless has certain drawbacks. We can cite:

• - the practical impossibility of obtaining knotless windings whose weight exceeds one kilo, on the one hand, due to the very fact of the covering material and on the other hand, because beyond this weight, we would then obtain too high tensions on the wrapping thread, which would cause on the finished wrapped thread the defect called "flash", by virtue of which in places the core thread is not perfectly covered, which on the fabrics, causes appearance defects and even weaknesses;
• - a high cost price, due to the appreciable electrical consumption required by the rotary drive of the spool of coating wire.

In the British patent GB-A-443 188, a method has already been proposed in which, firstly, an elastic rubber thread is assembled in parallel with two previously twisted threads, then in a second step, two of these threads thus assembled are twisted. In this way an elastic organ thread is obtained. This thread is unfortunately not suitable for the manufacture of ba or tights, because on the one hand, economically, it is impossible to make fine threads and on the other hand and above all, the elastic core thread, because of the assembly technique, is poorly covered, therefore is poorly protected against shelling, which is unacceptable.

The invention overcomes these drawbacks. It relates to a process which is both economical and allows for larger windings.

• - dans une première phase, à guiper le fil élasthane tendu avec le fil enrobant à une nombre de spires de l'ordre du tiers de la torsion usuelle de simple guipage et à réceptionner ce fil assemblé sur une bobine,
• - puis, dans une deuxième phase, à reprendre cette bobine de fil sur un organe donneur de torision pour lui communiquer une torsion complémentaire jusqu'à ce que l'on obtienne sur le fil un nombre de spires total égal à la torsion usuelle de simple guipage

This process of wrapping an elastane thread stretched three to five times by a so-called coating thread is characterized in that it consists:

• - in a first phase, guiding the stretched elastane thread with the wrapping thread with a number of turns of the order of one third of the usual twist of simple wrapping and receiving this assembled thread on a spool,
• - then, in a second phase, to take up this spool of wire on a torion-donating member to impart to it a complementary twist until a total number of turns equal to the usual twist is obtained on the wire covering

• - lors de la première phase:
  • - le fil enrobant est un fil synthétique, texturé ou non par fausse torsion,
  • - le nombre de spires d'assemblage est de l'ordre de 600 t/m,
  • - l'assemblage s'effectue à la simple guipeuse;
• - lors de la deuxième phase, a torsion complémentaire est donnée par une broche double torsion et la réception s'effectue sur une bobine biconique, afin de facilier le défilage du fil lors du tricotage.

In practice, advantageously:

• - during the first phase:
  • - the coating wire is a synthetic wire, textured or not by false twist,
  • - the number of assembly turns is around 600 t / m,
  • - assembly is carried out using a simple covering machine;
• - during the second phase, a complementary twist is given by a double twist spindle and the reception is carried out on a biconical coil, in order to facilitate the unwinding of the thread during knitting.

The "usual twist of simple wrapping" of a stretched elastane thread is perfectly known to technicians. This is the usual number of turns given to the wrapping wire by the covering machine to completely cover the stretched elasthane core thread, that is to say to cover this stretched core thread with contiguous but not superimposed turns of the thread. coating. As already said, this number of turns varies in the opposite direction to the title of the coating wire. The finer the coating wire, the higher this "twist". In practice, it is between 1000 and 3000 rpm.

In French patent application No. 7,218,229 of the Applicant, published under the number FR-A-2 185 207, it had already been suggested to assemble a spandex yarn and another yarn with the double twist spindle. Unfortunately, in the assembly thus produced, the stretched elastane thread was often poorly protected, which made its use prohibitive for multiple applications, so this technique had to be abandoned.

As already said, during the first phase, the number of wrapping turns must be of the order of one third of the usual twist of simple wrapping. If this number were lower, we would then no longer have a covering, but then an assembly in which the elastane thread would not be positioned in the middle, that is to say in the core, but would come to the periodically contrary on the surface, so that during the complementary torsion, this presence on the surface would be accentuated. The yarn thus obtained would be fragile, since the elasthane yarn would be poorly protected, therefore subject to scuffing. On the other hand, if the number of turns wound during the first phase is too high, for example greater than half the usual twist of simple wrapping, in addition to the unnecessarily high cost of such an operation, the defect of "flash" reappears - would appear and would even be accentuated after the second phase.

The manner in which the invention can be implemented and the advantages which ensue therefrom will emerge more clearly from the description which follows in support of the appended figures and from the examples of embodiment given by way of indication and not limitation.

FIG. 1 shows in section a rough assembly for the implementation of phase 1, while FIG. 2 is a rough assembly, seen in section, for the implementation of phase 2.

• Phase 1 (fig. 1)

• (1) le cylindre délivreur,
• (2) la bobine d'élasthane,
• (3) le fil d'élasthane tendu,
• (4) la broche creuse entraînée en rotation par la courroie,
• (6) la bobine de fil enrobant (7),
• (8) l'oeillet de guipage,
• (9) le cylindre d'entraînement derrière lequel est placé le guide-fil classique, non représenté, animé d'un mouvement transversal de va et vient,
• (10) l'enroulement sur bobine à joues (11) à partir du fil assemblé obtenu (12).

With reference to these figures, the following references designate:

• Phase 1 (fig. 1)

• (1) the delivery cylinder,
• (2) the spandex coil,
• (3) the stretched elasthane thread,
• (4) the hollow spindle driven in rotation by the belt,
• (6) the coil of wrapping wire (7),
• (8) the covering eyelet,
• (9) the drive cylinder behind which is placed the conventional thread guide, not shown, animated with a transverse movement back and forth,
• (10) winding on a spool (11) from the assembled yarn obtained (12).

Phase 2 (fig. 2)

• (12) the wrapped yarn in phase 1,
• (21) the pulley of the double twist spindle (for example of the DT 2055 type from ACBF),
• (22) a coronelle,
• (23) the torsion blocker of the double twist spindle proper, rotated by (21) on which the coil is placed
• (10) of wire (12),
• (24) the store,
• (25) the tray,
• (26) a balloon eyelet,
• (27) the over speed deliverer,
• (28) a reference,
• (29) the winding guide,
• (30) the call and winding cylinder,
• (31) the finished coated wire,
• (32) the reel-holder stirrup (33), for example of the biconical type on which the finished wire (31) is received.

Example 1

• - en âme (3): un fil élasthane de 40 deniers étiré d'environ quatre fois (bobine 2 de 500 g);
• - en enrobant (7): un fil texturé fausse torsion de polyamide 6,6 de 20 deniers/7 brins, tiré d'une bobine (6) de un kilo;
• - la broche (4) tourne à environ 11 000 t/m en S, ce qui donne un fil guipé (12) à nombre de spires de guipages d'enrivon 700 t/m en S.

On a simple covering machine (fig. 1), we assemble:

• - core (3): a 40-denier elastane thread stretched approximately four times (coil 2 of 500 g);
• - by coating (7): a textured false twist polyamide 6.6 thread of 20 denier / 7 strands, drawn from a reel (6) of one kilo;
• - the spindle (4) rotates at around 11,000 rpm in S, which gives a wrapped wire (12) with a number of wrapping turns of enivon 700 rpm.

Reception (10) takes place on a spool (11) with a diameter of 120 mm and a stroke of 200 mm.

This coil (10) is then placed (see FIG. 2) on a double twist spindle type 2055 of ACBF with a pot diameter of 140 mm. During this treatment, this coil (10) is therefore fixed.

The speed of rotation of the spindle (22-24) is about 15,000 rpm in S, which gives the wire (31) a complementary twist of 1200 rpm in S. The wire (31) therefore has a final number of turns of 1200 plus 600, or 1800 rpm in S. The coil (30) obtained weighs approximately 1.5 kg compared to 1 kg in the most favorable cases currently starting from a single covering machine.

The wire (31) obtained has excellent elasticity and very good coverage, so that for most common applications, it is advantageous to eliminate conventional heat treatments for fixing. This thread is perfectly suitable for the manufacture of woven or knitted fabrics, especially for the bottom legs.

This wire (31) can easily be identified in relation to a conventional wrapped single wire. In fact, in a conventional guided single wire, if the wire is disassembled, the core wire then commutes a twist equal to the number of wrapping turns. Thus, for a wire wrapped at 1800 turns in Sg during disassembly, the core wire receives a twist of 1800 turns in Z.

On the other hand, with a wire prepared in accordance with the invention, if this wire is disassembled, the core is then twisted by a value equal to the number of turns received during the wrapping of the first phase. So in this wire which has been twisted at 1800 rpm in S, if we communicate a reverse twist of 1800 rpm in Z to be able to separate the core from the coating, we will then find on the core wire not 1800 turns as with a single wrapped wire, but only a number of turns of 600 turns in Z.

Example 2

• - comme âme (3): un fil élasthane de 70 deniers étiré d'environ de trois fois et demi;
• - en robant (7): un fil grège en polyamide 6.6 de 30 deniers/10 brins.

Example 1 is repeated, but using:

• - as core (3): a 70 denier elastane thread stretched approximately three and a half times;
• - by taping (7): a raw polyamide 6.6 thread of 30 denier / 10 strands.

In addition, the number of turns in phase 1 is 700 rpm in S whereas in phase 2, it is 1400 rpm in S, which gives a final number of turns of 2100 rpm.

The wire obtained has the same properties as that obtained in Example 1.

Example 3

Example 1 is repeated, replacing the coating textured thread (7) with a raw thread of the same nature and the same title. The number of turns in the first wrapping phase is increased to 700 rpm. The rotation of the double twist spindle (22-24) is fixed at 13,000 rpm, which gives an additional twist of 1400 rpm. The wire (31) therefore has a final number of turns of 2100 rpm in S.

Example 4

Example 1 is repeated, replacing the core thread (3) with a 20-denier elasthane thread stretched four times and the coating thread (7) with a greige polyamide 6.6 thread of 17 dtex / 5 strands.

The number of wrapping turns in the first phase is 850 rpm in S. The additional twist given by the double twist spindle (22-24) is 1650 rpm in S. The finished yarn (31) has a final twist of 2500 rpm in S. This thread is perfectly suitable for the manufacture of tights or stockings.

In order to avoid twisting the leg of these stockings and to obtain perfectly balanced products, it is recommended to knit one fall with such a yarn in twist S and the next fall with the same yarn but with twist Z.

• - la possibilité d'obtenir industriellement des bobines de poids beaucoup plus élevé (1,5 kg contre 1 kg actuellement, soit une augmentation de l'ordre de 50%);
• - une consommation d'énergie réduite d'environ 30%;
• - donc une diminution substantielle du prix de revient.

The method according to the invention has many advantages over the methods currently used. We can cite:

• - the possibility of obtaining coils of much higher weight industrially (1.5 kg compared to 1 kg currently, an increase of around 50%);
• - reduced energy consumption of around 30%;
• - therefore a substantial reduction in the cost price.

In this way, these threads can be used successfully for all the known applications of gimped spandex threads.

Claims (6)

1. A process for covering an elasthane yarn (3) stretched from three to five times with a cover yarn (7), characterized by the fact that it consists:

- in a first step, in covering the elasthane stretched yarn (3) with the cover yarn (7) with a number of turns in the range of the third of the usual twist of a single covering and of winding this single covered yarn (12) on a bobbin (10);

- then, in a second step, in taking up this bobbin (10) of covered yarn (12) onto a twisting member (20, 24) to twist it in the same direction as the covering direction until to obtain on this yarn (12,31) a number of turns equal to the usual twist of a single covering.

2. Process according to claim 1, wherein during the first step, the number of turns of the assembly is about 600 t/m.

3. Process according to claims 1 and 2, wherein, during the first step, the low-twist covered yarn (12) is received on a flanged bobbin (11).

4. Process according to claims 1 to 3, wherein, during the second step, the additional twist is given by a two for one twist spindle (21, 23).

5. Process according to claim 4, wherein the finished yarn (31) is received on a biconical bobbin (30).

6. Process according to any previous claim, wherein during the first step, the cover yarn (7) is covered with a hollow covering spindle (6,4).

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