EP0070210A1 - Method and apparatus of manufacturing a doubled yarn - Google Patents

Abstract

1. A method of manufacturing a core yarn in which two rovings of fibres are separately drawn between a supply place and a pair of drawin rollers upstream of which a continuous filament is inserted into each roving, the two strands each formed by the roving of fibres and the continuous filament are twisted together by a false twisting means (7) by inserting them at the same convergence point (12) upstream of the false twisting means, the tension of the strands is adjusted, the strands are wound, and the resulting yarn is twisted on a twisting loom.

Description

The present invention relates to a method and a device for spinning core wires.

Core threads in which a core thread is wrapped in a sheath of staple fibers are known. Processes for obtaining core threads are described in particular in the patents of the United States of America No. 1,373,880, 2,024,156, 2,210,884, 2,313,058, 2,504,523, 2,526,523, 3,017 740 and 3,038,295.

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, yarns with spun cores generally have the disadvantage of being limited in the production speed to that of the empbyés machines and therefore to the twisting system used.

Self-twisted yarns obtained by natural twisting in one direction and in the other of two strands having previously received an alternating right and left twist are also known. A process for the manufacture of self-twisted yarns on a self-twisting loom and various applications are for example described in British patents Nos. 1,015,291, 1,121,942 and 1,084,371.

Self-twisted webs are known from the patent American 4,033,102.

An original embodiment of threads with self-twisted cores is described in French patents No. 79 18173 and 79 13995.

The advantage of this process is that it only requires unidirectional movements at constant speed. On the other hand, its great drawback is that it imposes abrupt 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 wires with respect to the 'soul.

This phenomenon is well known in continuous filament texturing, where if an air nozzle is used as a twister, the torsional efficiency varies enormously depending on the regularity of tension, which can result in the adoption of a tension regulator. at the spindle outlet.

The object of the present invention is to enable the production of core yarns with an extremely high production speed, obtained by suppressing the variations in tension inherent in self-twisted core yarn systems.

This object is achieved by a process for spinning core yarns, a process in which at least one strand of fibers is stretched between a point of supply of this strand and a pair of stretching cylinders, upstream of which a filament is optionally introduced. continuous and in accordance with the invention the strand formed by the wick of fibers and optionally the continuous filament is twisted with at least one strand formed by a continuous filament and possibly a wick of fibers, by a friction torsion member by introducing them in the same point of convergence upstream of the torsion member, the tension of the strands is adjusted before the winding by passing them, after the twisting member, through a pair of delivery cylinders and twisting after bobi swims the wire thus formed by the strands on a twisting loom. The continuous core wires are optionally supplied with constant voltage. The wire formed by the strands is twisted on a conventional twisting loom, for example with a slider ring or a double twist to give the final twist.

Thus, according to the invention, one or more strands of fibers are stretched separately between supply points and pairs of stretching cylinders, the continuous core wires are optionally supplied with constant tension, they are introduced into said strands upstream different stretching cylinders, and the strands formed at one point of a torsion member are made to converge before the assembly is wound. The assembly formed by the strands is then put on a twisting loom to give the final twist.

• - des moyens de réalisation d'au moins deux brins dont l'un est constitué d'au moins une mèche de fibres et éventuellement d'au moins un filament continu et le second est constitué d'au moins un filament continu, et éventuellement au moins une mèche de fibres.
• - des moyens de fausse torsion par friction des brins,
• - des moyens de réglage de la tension des brins situés en aval des moyens de torsion,
• - des moyens de bobinage, et
• - des moyens de retordage du fil formé par les brins.

This object is also achieved by a device for spinning core threads comprising at least one core thread, in particular a continuous filament, and at least one sheath of fibers surrounding the core thread, said device comprising:

• means for producing at least two strands, one of which consists of at least one wick of fibers and possibly of at least one continuous filament and the second of which consists of at least one continuous filament, and optionally at minus a wick of fibers.
• - means of false twisting by friction of the strands,
• means for adjusting the tension of the strands located downstream of the torsion means,
• - winding means, and
• - means for twisting the wire formed by the strands.

• La figure 1 est une vue schématique, en perspective d'un dispositif permettant d'obtenir un fil à âme double avant la montée en torsion ; la figure 2 est une vue de face d'un type de tordeur utilisé pour conférer la fausse-torsion ; la figure 3 est une vue schématique de la position du point de convergence ; la figure 4 est une vue à plus grande échelle d'un condenseur permettant de condenser les fibres sur le filament continu.

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 device for obtaining a double core wire before the torsional rise; Figure 2 is a front view of a type of twister used to impart false twist; Figure 3 is a schematic view of the position of the point of convergence; Figure 4 is an enlarged view of a condenser for condensing the fibers on the continuous filament.

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. At the same time, a wick of fiber 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) at least one continuous filament (6a, 6b) is introduced. The tension of these filaments is adjusted by tension adjustment means 19a, 19b, for example the cylinder and strap devices 19a, 19b. 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 wound on a cylinder 11.

It is 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 twist and the running speed. Indeed, a twist exists in each single strands formed by a wick of fibers and a continuous filament, 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, a twist part is incorporated in the strands in a randomly varying manner. However, such a twist is of low intensity.

As can be seen, the strands are wound on the cylinder 11. Then, in a subsequent step, the strands are twisted on a twisting loom for example.

If the tension communicated by the wringer 7 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, continued poor attachment of the fibers to the continuous filament. For example, excellent results have been obtained at the speed of 300 meters per minute with a stretch, between the stretchers 4 and the deliverers 10, equal to 1.53% and a 2x25 Tex thread composed of a continuous filament core 50 decitex and a wool fiber blanket of 22.5 microns. Thus, the difference in speed between the stretching cylinders 4 and the delivery cylinders 10 is adjusted as a function of the spinning parameter and of the displacement speed. If, on the other hand, the tension is too high, the core thread is too tight, which causes a risk of the cover fibers slipping at the slightest friction.

After the wringer 7, there is no assembly twist, that is to say that there is no self-twist. But there remains a small residual twist in each of the two strands. This very small residual twist is actually random slightly to the right and slightly to the left and due to the irregularities mentioned above which means that the torsion existing between the stretching cylinders 4 and the point of convergence 12 is unidirectional but with a variable intensity of torsion. ¹

However, it has been found that this residual alternating twist is sufficient to ensure cohesion without having the sliding of the covering fibers relative to the core which makes it possible to twist this thread on a conventional twisting loom. For example, good results have been obtained with the 2x25 Tex wire described above on a double twist loom with a spindle speed of 11,000 rpm and a twist of 350 rpm, a development of 62.8 m per minute.

The assembly of the two strands before the twister 7 is important in the sense that it serves as a voltage regulator. Indeed, as shown in Figure 3 where the position 13 of the point of convergence represents the average position, position 14 corresponds to the point of convergence when there is a size in one of the two strands where less torsion is communicated. by the twisting organ. Position 15 corresponds to the point of convergence when there is fineness in the strand. The assembly of the two strands is also necessary according to the invention, since the cohesion between the strands makes it possible to keep the alternating twist on each of the strands, which has the effect of preventing the fibers from sliding on the filament.

This phenomenon can also be used, advantageously, in order to detect the presence or absence of cover wires on the core by the variation of the point of convergence. Indeed, if for some reason the coverage of the fiber sheath runs out, for example during a breakage of the wick of fibers, the point of convergence 15 will go up very high, for example, it will go up to the point 15a, the position of which of course varies according to the tension settings.

If a contactor 26 is placed between point 15 and point 15a, on the axis joining the points of convergence 13, 14, 15, 15a, when the fiber in the wick of fiber runs out, the ascent of the point of convergence 15 towards point 15a causes the switch 26 to toggle. This contactor can then actuate various commands, for example commands for supplying fiber filament, or commands for raising the yarn take-up reel 11, or even l stop of the twisting member 7, etc.

Furthermore, the presence or absence of a strand formed either of a single strand of fiber or of a strand of fiber and of a continuous filament is detected by varying the position of the wire 18 formed in upstream of the twisting member 7 (see FIG. 3).

Indeed, two contactors 27, 28 are placed located on either side of the wire 18, upstream of the twisting member 7. When a strand, for example the strand 5a, 6a comes to be absent, the strand 5b , 6b takes a position 5'b, 6'b between the stretching cylinder 4b and the twisting member 7. This position which is displaced outwards relative to the line formed by the points 13, 14, 15, 15a a then tend to move the contactor 28, which acts as the contactor 15a. Symmetrically, when the strand 5b 6b runs out, the strand 5a 6a moves outward relative to the line of the points of convergence 13, 14, 15, 15a and then acts on the contactor 27 which itself acts on the control means making it possible to stop the supply of filaments, fibers, etc.

Thus, according to the invention, a core wire is obtained which does not have any discontinuity, such as knots, splices or stops and which allows the production of coils of wire of significant weight, for example having a weight of at least 1 kg for fine threads, for example around 10 tex and spools of thread of at least 10 kg for coarse threads, for example for threads around 1000 tex.

Furthermore, FIG. 2 represents an example of a wringer 7 which can be used without limitation, or as indicated in French patent No. 1,147,515 (American patent No. 2,943,433), plans to pass the twisting yarn between two endless, movable belts (16, 17), these belts being arranged obliquely to each other so that the yarn 18 is given an impulse in the direction of its movement during its passage between the belts.

Between the drawing sleeves (3a, 3b) and the drawing cylinders (4a, 4b) there is a condenser 20 known per se which is used to condense the fibers on the continuous filament. Usually, the filament is introduced into the center of the wick of fibers and then downstream of the drawing line 22, the strand receives the twist which ensures the attachment of the fibers to the filament. In the case of very high speed, it may happen that the twist is not sufficient to ensure the attachment of the outside fibers of the web. This results in a significant loss of fiber.

To overcome this drawback, it has been found that by introducing the filament 6 on the outside of the condenser 20, therefore parallel to the generator 25 of the cylinder of revolution formed by the wick 5 and along this generator, the fibers of hang perfectly (see figure 4). The generator 25 is located on the side opposite the point of convergence 12 with respect to the wick (s) (5a, 5b).

A variant of the invention is such that one can work on a larger number of stretching systems than that described in FIG. 1.

Another important variant is that one can work on one of the strands, with an assembly composed of a continuous filament and a sheath of fibers while another strand is composed only of a continuous filament. . We sup therefore premium a fiber sheath 5b. For example, good results have been obtained, at the speed of 200 meters per minute, with a resultant 71.5 tex thread, composed of a 72 decitex core and a fiber sheath on one of the strands. and a continuous filament of 72 decitex on the other strand.

A third variant is that one can work on one of the strands, with an assembly composed of a continuous filament and a sheath of fibers while another strand is composed only of a sheath of fibers, provided that there are enough fibers in section. We therefore delete a continuous filament, for example filament 6b.

A fourth variant is that one can work on one of the strands composed of a continuous filament, while the other strand is composed only of a sheath of fibers, provided that there is sufficient fibers in section. There is then a single continuous filament, for example the filament 6a and a single sheath of fibers, for example the sheath of fibers 5a.

Claims (18)

1. A method of spinning a core thread of the type comprising at least one sheath of fibers surrounding at least one continuous filament, according to which at least one wick of fibers is stretched between a point of supply of this wick and a pair of stretching cylinders, upstream of which a continuous filament is optionally introduced, characterized in that: - the strand formed by the wick of fibers and possibly the continuous filament is twisted with at least one strand formed by a continuous filament and possibly a wick of fibers, by a friction torsion member (7) by introducing them at the same point convergence (12) upstream of the torsion member; - we adjust the tension of the strands - then the strands are wound and - Twist the wire thus formed on a twisting loom, after winding. 2. Method according to claim 1, characterized in that the tension of the strands is adjusted before the winding by passing them, after the twisting member (7), through a pair of delivery cylinders (10). 3. Method according to any one of claims 1 and 2, characterized in that the core filament (s) (6a, 6b) are introduced into the rovings (5a, 5b) of fibers before imparting the twist. 4. Method according to any one of claims 1 to 3, characterized in that each core filament (6a, 6b) is introduced along the generator (25) situated on the side opposite to the point of convergence (12 ) relative to the wick into which the filament is introduced. 5. Method according to any one of claims 1 to 4, characterized in that each filament is introduced continuous upstream of the stretching cylinders under constant tension. 6. Method according to any one of claims 1 to 5, characterized in that one adjusts the tension of the strands before winding by adjusting the speed difference between the delivery cylinders (10) and the stretching cylinders (4) 7. Method according to any one of claims 1 to 6, characterized in that the presence or absence of covering wires on the core is detected by the variation of the position of the point of convergence. 8. Method according to any one of claims 1 to 7 characterized in that the presence or absence of a strand is detected for the variation of the position of the wire formed upstream of the twisting member (7) . 9. Device for implementing the method according to any one of claims 1 to 8 for the spinning of core threads comprising at least one core thread, in particular a continuous filament and at least one sheath of fibers surrounding the thread of soul, said device comprising: - Means for producing at least two strands-one of which consists of at least one wick of fibers (5a) and possibly of at least one continuous filament (6a) and the second consists of at least a continuous filament (6b) and optionally at least one wick of fibers (5b), - means of false twist (7) by friction of the strands, means for adjusting (10) the tension of the strands located downstream of the torsion means (7), - winding means (11) and - means for twisting the wire formed by the strands. 10. Device according to claim 9, characterized in that the means for producing a strand comprise a pair of feed rollers (2) of a wick of fibers, a pair of drawing sleeves (3) of the wick, a pair of stretching cylinders (4) of the wick, a device with rolls and strips (19) regulating the tension of the continuous filament, a condenser (20) located between the drawing sleeve (3) and the drawing cylinders (4); the means for frictionally twisting the strands comprise endless movable belts (16, 17); the means for adjusting the tension of the strands comprise delivery cylinders (10) whose speed is adjusted relative to the speed of the stretching cylinders (4); the twisting means consist of a twisting loom. ₁ 1. Device according to any one of claims 9 and 10, characterized in that it comprises at least two means for making strands. 12. Device according to any one of claims 9 to 11, characterized in that it comprises a contactor (26) placed between the highest point of convergence (15) in the presence of fibers and the point of convergence ( 15a) in the absence of fibers. 13. Device according to any one of claims 9 to 12, characterized in that it comprises two contactors (27, 28) located on either side of the wire (18), upstream of the twisting organ (7 ). 14. Core wire manufactured by the method according to any one of the reve ndicat ions 1 to 8, characterized in that it does not present any discontinuities such as knots, splices or stops and allowing the production of coils of son of a large weight, for example at least 1 kg for fine yarns, for example around 10 tex and at least 10 kg for coarse yarns, for example around 1000 tex. 15. Core wire according to claim 14, characterized in that it consists of a first strand formed of a continuous filament and a sheath of fibers and of a second strand formed continuous filament and fiber sheath. 16. A core wire according to claim 14 characterized in that it consists of a first strand formed of a continuous filament and a sheath of fibers and of a second strand formed of a filament. 17. A core wire according to claim 14, characterized in that it consists of: a first strand formed of a fiber sheath and a second strand formed of a continuous filament and a fiber sheath . ₁ 8. core wire according to claim 14, characterized in that it consists of a first strand formed of a fiber sheath and a second strand formed of a continuous filament.

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