EP0217345A2 - Method and apparatus for spinning staple fibre yarns - Google Patents

Abstract

1. Process for spinning fibre yarn in which at least two rovings of fibres are stretched between the roving feed points and pairs of stretching rollers ; the strands formed by each roving of fibres are twisted using a twisting device notably friction (7) ; they are brought together to the same point of convergence (12) ; the strands (11) are wound onto a reel ; the yarn formed by the assembly of strands is retwisted on twisting machine, the strands are wound on a reel, characterised by the fact that during twisting the strands are subjected to retwisting which sets up in them a false twist between the reel yarn feed point and the twist application point.

Description

The present invention relates to a method and a device for spinning fiber yarns.

Yarn production can be performed on many spinning systems. We know, in particular, ring-cursor systems, self-twisting systems, those with free ends, wrapping etc ...

A special case of thread is found in core threads, in which a core thread is wrapped in a sheath of staple fibers. Processes for obtaining core yarns are described in particular in the patents of the United States of America No. 1373880, 2024156, 2210884, 2313058, 2504523, 2526523, 3017740 and 3038295.

The production of core yarns can be carried out on numerous spinning systems commonly used for the manufacture of yarns from staple fibers. However, and in particular with the ring-cursor system, threads with spun cores generally have the disadvantage of being limited in the speed of production to that of the machines used and therefore to the twisting system used.

Self-twisted core yarns are known from United States patent No. 4033102. An original embodiment of self-twisted core yarns is described in French patents No. 7918173 and 7913995. The advantage of this process is to require only unidirectional movements at constant speed. On the other hand, its great drawback is that it imposes sudden and significant variations in torsion and therefore in tension which limit their efficiency at the level of production speed, and increase the risks of slipping of the covering fibers with respect to blade.

French patent N ° 8111642 avoids these drawbacks and allows a high production speed without slipping of the fibers. cover relative to the core and performs after twisting a unidirectional twist of the ply. Its great drawback is that it requires the use of one or more continuous filaments serving as a vector for the covering fibers, which can be a drawback in the final product.

The present invention aims to allow the production of fiber yarns with or without a core with an extremely high production speed, obtained by consolidating the resistance of the fiber yarn, preferably when it has to withstand forces .

This object is achieved by a process of spinning a yarn of fibers according to which one stretches at least two wicks of fibers between points of supply of this wick and pairs of stretching cylinders; the strands formed by each wick of fibers are twisted by a torsion member, in particular a friction member; they are brought together at the same point of convergence; the twisted yarn formed from the assembled strands is twisted on a twisting loom, the strands are spooled, characterized in that the strands are given false twist between the point of unwinding the yarn on the spool and the point of taking the twist .

This process is such that the thread is given at a precise determined point, sufficient cohesion to allow twisting. Thus, there is no break in the fiber yarn.

The yarn is twisted on a conventional twisting loom, for example with a slider or double twist or double step loom to give the final twist.

According to a particular embodiment of the invention, at least two wicks of fibers are stretched separately between supply points and pairs of stretching cylinders; the strands formed at the same point of a torsion member are made to converge; the strands formed are passed through a pair of delivery cylinders; we reel. Then, we put the thread on a twisting loom and we assure a resistance of the thread between the point of unwinding of the thread on the spool and the point of torsion, thanks to a false twist.

A device for implementing the method comprising:
. means for producing at least two strands, each consisting of at least one wick of fibers;
. means for false twisting of the strands;
. winding means;
. means for twisting the wire formed by the strands;
is characterized by the fact that it comprises means of false twist between the unwinding from the reel and the twisting.

The wound wire is formed of at least two strands placed side by side having a low residual twist, possibly alternating, very low, sufficient to ensure cohesion of the covering fibers on the filament and insufficient to cause the assembly of the two strands by self-twisting regularly and constantly.

The yarn after twisting is such that the fibers are all substantially parallel to each other in the axis of each strand with a variation equal to the very small residual twist existing in the yarn before twisting, but such that we know how to dissociate the two strands per twist.

• . la figure 1 est une vue schématique, en perspective d'un dispositif de filage avant l'arrêt du filament continu dans le cas où le point de convergence est en amont du tordeur.
• . la figure 2 est une vue schématique en perspective d'un dispositif permettant d'obtenir un fil double avant la montée en torsion et après la coupe du filament, dans le cas où le point de convergence est en aval du tordeur.
• . la figure 3 est une vue en perspective d'un dispositif, permettant d'obtenir une résistance du filé entre le point de dévidage du fil sur la bobine et le point de prise de torsion d'un métier à retordre.
• . la figure 4 est une vue en coupe dudit dispositif de la figure 3, monté sur la coronelle de dévidage d'une retordeuse double torsion.
• . la figure 5 est une vue en perspective d'une variante du dispositif de la figure 3.
• . la figure 6 est une vue en perspective d'une autre variante du dispositif de la figure 3.
• . la figure 7 est une vue schématique du dispositif de la figure 5, monté sur un métier à retordre à anneau-curseur.

The invention and the advantages which it brings will however be better understood thanks to the examples of implementation, given below by way of illustration, but not limitation and which are illustrated by the appended figures in which:

• . Figure 1 is a schematic perspective view of a spinning device before stopping the continuous filament in the case where the point of convergence is upstream of the twister.
• . Figure 2 is a schematic perspective view of a device for obtaining a double wire before the rise in torsion and after cutting the filament, in the case where the point of convergence is downstream of the twister.
• . Figure 3 is a perspective view of a device, for obtaining a resistance of the yarn between the wire unwinding point on the spool and the point of torsion taking of a twisting loom.
• . Figure 4 is a sectional view of said device of Figure 3, mounted on the coronelle of unwinding of a double twist twister.
• . FIG. 5 is a perspective view of a variant of the device of FIG. 3.
• . FIG. 6 is a perspective view of another variant of the device of FIG. 3.
• . Figure 7 is a schematic view of the device of Figure 5, mounted on a twisting loom ring-cursor.

According to the invention, a spinning process is carried out by stretching a wick of fibers 5a between a supply point 2a and a pair of stretching cylinders 4a. The drawing system further comprises a pair of drawing sleeves 3a. In parallel, a strand of fibers 5b is stretched separately by a drawing system comprising a supply point, namely a pair of food cylinders 2b, a pair of drawing sleeves 3b and a pair of drawing cylinders 4b.

Upstream of the stretching cylinders 4a, 4b, a continuous filament 6a, 6b is introduced. Two strands are therefore formed, each consisting of a wick of fibers and a filament. The strands thus formed are twisted together by a wringer 7 and are guided by two guides 8 and 9. The two strands then pass through a pair of cylinders 10 before being aspirated by a vacuum cleaner 13 before removing the continuous filaments, for example by cutting, by means a pair of manual scissors, upstream of the stretching cylinders.

The continuous filaments thus cut are therefore brought by the vacuum cleaner 13 to the waste.

FIG. 2 shows the spinning device after cutting the filaments, when the fiber yarn is wound on a cylinder 11.

It is important to have a sufficient number of fibers in section, in relation to the cohesion of the fibers, the cleanliness of the wick and the tension between the stretchers 4 and the delivery cylinders 10. About the cohesion between the fibers, it it may be advantageous to add to the fibers, when preparing the wicks, a size increasing this cohesion between the fibers. For example, a paraffinic sizing agent or a sizing agent containing colloidal silica. This also has the effect of facilitating twisting.

In the case where the point of convergence is upstream of the torsion member, it is also important to adjust the tension between the stretchers 4 and the delivery cylinders 10, so as to have a suitable distance h between the stretchers 4 and the point of convergence 12 of the wires, in relation to the given torsion and the running speed. Indeed, a twist exists in each of the single strands, between the point of convergence 12 of the strands and the point where the strand is lastly gripped by the stretchers 4, but this twist is not incorporated in the resulting wire. This twist exists in the strands prior to convergence in an amount of equilibrium which depends on the geometry of the system and the spinning parameters. This state of affairs described above can in practice be modified. Indeed, irregularities occurring randomly in the strands, part of the twist is incorporated into strands in a randomly varying manner. Such a twist is however of low intensity.

If the tension is too low, too little torsion is found in the strand between the stretching cylinders 4 and the point of convergence 12, which results in fiber losses at the outlet of the stretching cylinders 4, following poor attachment. fibers. For example, excellent results have been obtained at a speed of 215 meters per minute with a stretch, between the stretchers 4 and the deliverers 10, equal to 1.53% and a 2 × 25 tex yarn composed of 45% wool 27 microns and 55% 3 denier polyester. Thus, the difference in speed between the stretching cylinders 4 and the delivery cylinders 10 is adjusted as a function of the spinning parameters and the speed of movement. If the tension is too high, the thread is too tight, which leads to a risk of breakage.

In the case where friction torsion members are used, ensuring both a torsion component and a thread advancement component, it may be advantageous to adjust the tension of the thread by varying this advancement component, independently. the tension adjustment between the delivery and stretching cylinders. For example, when using two endless crossed belts, this adjustment is made by varying the angle of the two belts.

When the fiber spun yarn is in the twisting stage, its resistance is generally too low to allow smooth running and the yarn often breaks between the point of unwinding the yarn on the spool and the point of twisting.

However, it has been found that a very slight additional cohesion is sufficient to ensure the unwinding of the wire. Depending on the initial cohesion of the fibers, a simple cohesive sizing may be sufficient. This cohesive product can be added to the fibers, either at the level of the preparation of the wicks or at the level of the spinning machine, between the twist member of the strands and the winding member.

In cases where this is not sufficient or when the use of sizing is prohibited, it has been found that the addition of a few turns of twist, using a false device twisting was enough to ensure proper reeling.

False twist devices are known. They can be rotary or operate by friction. They can be static and a simple winding on a rod can ensure a torsion by rolling upstream of the rod when one pulls on the wire, provided that the angle of the wire relative to the rod, the diameter of the rod according to that of the wire as well as the pitch of the wire on the rod and the coefficient of friction of the material of the rod, are judiciously chosen.

The example in Figure 3 is a device that achieves these requirements. It consists of a body 14 of light material which supports a rod 15 in the form of a semicircle on the upper part of the body 14.

The use of the device of FIG. 3 will however be better understood thanks to FIG. 4 which represents a section of a double twist twisting spindle in which the coil of wire 16 is placed on the pot 17 where it is centered thanks to the centering device 18. The wire 19 is unwound in the process, leaving the reel passes through the eyelet 20 of the wire feeder 21. the wire is then wound on the rod 15 which is supported by the body 14, itself fixed by any means not shown, on the coronelle 21. After having made a certain number of turns the wire enters the body of the extension 22 where it will receive the first twist turn given by the torsion disc (not shown) for then pass between the pot 17 and the anti-balloon 23 where it receives the second twist before being wound on a reel not shown.

In general, in a double twist twisting machine, the thread tension and therefore the number of turns of winding on the torsion disc is adjusted by a spring piston, torsion blocker, not shown, which is in the extender 22.

In the case of the use of the device, according to the invention, it is necessary either to remove this piston and thus the torsion goes up to the rod 15, or to have a distance between this piston and the rod 15, less than the length of the fibers.

Using the device, the thread tension is adjusted, by adjusting the following parameters:
. number of turns of winding of the wire 19 on the rod 15,
. diameter of the rod 15,
. coefficient of friction of the material of the rod 15,
. angle α formed by the wire 19 and the rod 15 when the wire arrives on the rod.

We can vary the rotation of the wire feeder 21 by conventional means, for example, its weight, its coefficient of friction, etc. We can, as with a conventional double twist twisting machine play on the force of the spring of the torsion blocker, if it is used.

For example, good results have been obtained with the 2 x 25 tex yarn, described previously on a double twist twist loom with a spindle speed of 11,000 rpm and a twist of 371 rpm, a development of 59 , 2 meters per minute, using the device described in Figure 4 where the wire made a turn on a spring steel rod of 0.5 millimeter in diameter, without using a torsion blocker.

Good results have been obtained with a 2 x 33 tex yarn, one strand of which consists of a 300-denier filament made of shiny triacetate, without fiber covering and the other strand, consisting of fibers of 100% matt acrylic 3 deniers, without filament. The whole being twisted to 260 spindle turns at a double twist spindle speed of 10,000 revolutions per minute using the device described in Figure 4 where the wire 19 made 2 turns of winding on the rod 15 which had a diameter 0.25 millimeter, and without using a torsion blocker.

A variant of the device is shown in Figure 5 where the wire is wound on a straight rod.

Depending on the yarns to be twisted, it will be possible to have different angles of the rod relative to the vertical, so as to change the angle of the yarn relative to the rod in order to vary the intensity of false twist.

The examples of form of device described are given without limitation. The only imperative is to have a winding of the wire on the rod with an appropriate angle of the wire with respect to the rod. More generally, any device is used which allows a false twist between the unwinding and the taking of torsion, which allows the unwinding of the wire during twisting without it breaking due to its low resistance.

Another variant of the device is shown in Figure 6 where the rod is spiraled into a cone.

In the case where one twists by another twisting technique, for example with a continuous twisting ring, as shown in Figure 7, it will suffice to place a rod 24 between the coil 25 and the deliverers 26 to have a certain angle of the wire relative to the rod so as to give a false twist sufficient for the unwinding, in order to obtain a distance between the rod and the deliverers less than the length of the fibers. the tension in this case is given by the cursor weight 27.

In the case where one twists by the two-step twisting technique, it will suffice to adapt the device of FIG. 7 to the first twisting assembly step.

Claims (4)

1) A method of spinning a yarn of fibers according to which at least two wicks of fibers are stretched between points of supply of this wick and pairs of stretching cylinders; the strands formed by each wick of fibers are twisted by a torsion member, in particular a friction member (7); they are brought together at the same point of convergence (12); the twisted yarn formed from the assembled strands is twisted on a twisting loom, the strands are spooled, characterized in that the strands are given false twist between the point of unwinding the yarn on the spool and the point of taking up torsion. 2) Method according to claim 1, characterized in that one twists the wire after winding on a twisting loom by giving false twist to the strands between the point of unwinding of the wire on the spool and the point of taking torsion by winding the wire on a rod making an angle with the wire, at a location located at a distance from the point of twisting, less than the length of the fibers. 3) Device for implementing the method according to any one of claims 1 and 2, comprising:
. means for producing at least two strands, each consisting of at least one wick of fibers (5a)
. false twist means (7) of the strands;
. winding means (11);
. means for twisting the wire formed by the strands;
characterized by the fact that it comprises means of false twist between the unwinding from the reel and the twisting. 4) Device according to claim 3, characterized in that that the means of false twist are by winding the wire around a rod making an angle with the wire and placed between the point of wire unwinding on the spool and the point of twisting at a distance from the point of taking twist less than the length of the fibers.

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