EP0053093B1 - Method of untwisting a length of a textile yarn, and device for applying this method - Google Patents

Abstract

To unravel a terminal portion of a textile yarn, in particular in preparation for joining that yarn to another one by twisting their ends together, an extremity of the yarn is vibrated to loosen the fibers while a part of the yarn spaced from its end is held fast and the yarn extremity is combed or subjected to an aspirated air stream to remove loose fibers. In a preferred arrangement the air stream also causes vibration of a flexible tongue mounted in an air duct alongside the yarn extremity to oscillate its fibers.

Description

The subject of the present invention is a method for undoing a portion of a textile thread, held by at least one of its ends, and a device for implementing this method.

To tie two textile threads, you can make a knot that gives a solid but visible connection. You can also make a knotless knot by different methods. This tie is less visible than the knot, but it generally weakens the thread. The ideal consists in recreating the initial conditions of twisting of the wire, as proposed, for example, in the specification of US Pat. No. 2,362,801 or in that of US Patent 3,903,680. It appears from the latter that to obtain good resistance of the reattachment, the fibers of the two ends to be reattached must be separated beforehand so that they can then interpenetrate before subjecting them to a twist. If one is content to twist the two ends together without there being interpenetration of the fibers beforehand, the resistance of the piecing is extremely low because the two bundles of fibers are wound in a helix one around the other, most of the fibers then not participating in the strength of the piecing.

To obtain a bundle of separate fibers in order to allow their interpenetration with another bundle of fibers, formed in the same way at the other end of the wire to be attached, it suffices to untwist each of these ends and to arrange the fibers in parallel to each other and separate from each other. However, the separation of the fibers by twisting is only possible when it is a yarn obtained by spinning on a ring-cursor loom. On the other hand, it is not possible to do so in particular with yarns obtained by the so-called “open-end” spinning process or with plied yarns. In the first case, the fibers do not form more or less parallel and regular helices, but are much less well ordered, some extend longitudinally and others are wound around. Consequently, a simple twist is not enough to undo a portion of such a thread since all the fibers are not twisted together. In a plied yarn, you must first undo the plied yarn and then undo each yarn, the twisting of plied and that of the yarns being in the opposite direction.

A mode of wire joining described in US-A-4 263 775 shows that one can prepare the ends of wires to be tied up by holding them at one end and by introducing their cut ends into two suction nozzles. According to this document, it is planned to communicate to the air flows of these nozzles vortex movements intended to untwist the ends of the wires and to facilitate the separation of the non-held fibers in order to prepare them for the connection. Experience has shown that this mode of separation of the yarns is only effective for yarns spun according to the ring-cursor method, but not in the case of other types of yarns such as those mentioned above.

It therefore appears that the methods according to documents US-A-4,263,775 and US-A-3,903,680 are not suitable for all types of wire and that they can only be implemented if it is possible to undo the fibers by a means other than untwisting.

This is precisely the aim that the present invention proposes to achieve, in order to allow the connection in particular by twisting of interpenetrating fibers, whatever the type of yarn.

To this end, the invention relates to a method according to claim 1.

It also relates to a device for implementing this method according to claim 5.

The characteristics and advantages of the method and of the device for its implementation will emerge more clearly from the detailed description which follows and in which the principle used in the method and some embodiments of the device for the implementation of the method are described.

• La fig. 1 illustre schématiquement le principe utilisé dans le procédé.
• La fig. 2 représente schématiquement une première forme d'exécution du dispositif.
• La fig 3 est une coupe, à plus grand échelle, selon la ligne III-III de la fig. 2.
• La fig. 4 est une vue en élévation d'un appareil de rattache, partiellement coupé, muni de deux dispositifs selon une deuxième forme d'exécution.
• La fig. 5 est une coupe, à plus grande échelle, selon la ligne V-V de la fig. 4.
• La fig. 6 est une vue en élévation d'une variante de l'appareil de la fig. 4, muni d'un dispositif selon une troisième forme d'exécution.
• La fig. 7 est une vue selon la ligne VII-VII de la fig. 6.

process with reference to the accompanying drawings, given by way of example, in which:

• Fig. 1 schematically illustrates the principle used in the method.
• Fig. 2 schematically represents a first embodiment of the device.
• Fig 3 is a section, on a larger scale, along line III-III of fig. 2.
• Fig. 4 is an elevational view of a connecting device, partially cut, provided with two devices according to a second embodiment.
• Fig. 5 is a section, on a larger scale, along the line VV of FIG. 4.
• Fig. 6 is an elevational view of a variant of the apparatus of FIG. 4, provided with a device according to a third embodiment.
• Fig. 7 is a view along the line VII-VII of FIG. 6.

Fig. 1 shows a portion of wire F, one end of which is fixed at P and the other end of which carries a weight M of approximately 5 to 10 g. Under the action of the latter the thread will become untwisted. If it is a thread obtained on a slider ring loom, the weight M will fall after a certain number of turns carrying with it the untwisted fibers which are not retained in P. On the other hand, if it s 'is a yarn obtained by the open-end spinning process, all the fibers will not participate in the untwisting since some of them did not participate directly in the average twist of the yarn, so that the weight M will be obtained by these fibers and will not fall.

Fig. 1 shows, in addition, a vibrating blade L fixed on a support so that it is close to the wire and parallel to it. An electromagnet E, supplied with current pulses by a generator G, is arranged so as to make the blade L vibrate. By making the blade L vibrate, vibrations are communicated to the fibers of the wire F, which will have the consequence the reduction of their coefficient of friction and their dislocation, so that all the fibers not retained in P will separate under the action of the weight M and this one will fall after a certain time so far that the frequencies of the blade L and of the pendulum system formed by the wire F and the weight M are different and not harmonic. In this case, the frequency of the blade L is 100 Hz and the separation of the fibers, under the action of the weight M, occurs in a few seconds. There is therefore obtained at the free end of the wire F a bundle consisting of all the fibers retained at P, the length of which corresponds substantially to the average length of the fibers. This is an important factor in obtaining good bonding of the wire.

The experience described above demonstrates the effectiveness of the principle used in the method according to the present invention, principle according to which the vibrations imparted to the fibers of a wire cause the reduction of their coefficient of friction and the dislocation of all the fibers, thus also of those which did not take part in the average twist of the wire, which the untwisting alone does not make it possible to obtain.

The device shown in fig. 2 comprises a comb C connected to a transducer T, associated with a pulse generator G via an amplifier S. The transducer T is associated with a worm screw V driven by a motor D.

To undo the portion of wire F, one end of which is held in P, insert the teeth of the comb C into the wire F (fig. 3) and put them in vibration by means of the amplifier S. As can be seen in fig. 3, the teeth of the comb C are arranged to open the wire F and cause the fibers caught between two teeth to retain a certain freedom so that, when the comb C vibrates, its teeth strike the fibers and thus communicate vibrations to them . Simultaneously, the assembly formed by the comb C, the amplifier S and the transducer T is driven by the worm screw V in the direction opposite to the pinch point P. The displacement of the comb C causes the fibers to be untwisted and separated ( fibers) not retained at the pinch point P. In addition, the vibrations reducing the coefficient of friction of the fibers cause the dislocation of these fibers and facilitate the progression of the teeth of the comb C. As soon as the latter arrives at a distance from the pinch point P corresponding to the length of the fibers, the yarn is undone and the fibers not retained in P are separated and eliminated.

The device described above makes it possible to obtain a fairly satisfactory result, but on condition that the displacement of the comb C is relatively slow. However, despite this precaution, it often happens that a blockage of the comb occurs. In addition, the means for vibrating the vibrating member are quite complex and expensive, which is obviously a drawback which causes significant harm to the use of this device in a connecting device.

This is the reason why a solution has been sought in which the vibrating member is driven pneumatically, the pressurized air being widely available in the textile industry and the range of frequencies then depending only on the natural frequency of the vibrating member which can be sized accordingly. In addition, the energy transmitted to the wire can be greater than the energy developed in the device described above.

Two embodiments of such a device will now be described, each in the context of a connecting device with which the device is associated.

The apparatus illustrated in fig. 4 is, for the most part, that shown and described in the specification of Swiss Patent No 623 290 to which reference may be made for more details, since the present description will be limited to the elements necessary for understanding the invention.

This device essentially comprises two pins 1 and 2 mounted rotatably each in a support 3 and 4 respectively, mounted oscillating in a frame 5 along an axis orthogonal to that of the spindle. Each of these pins 1 and 2 ends at one of its ends with a circular head 6, respectively 7, split radially 6a, respectively 7a, to allow the wire F to engage in this circular head 6, respectively 7 and s 'wrap around pin 1, respectively 2. The supports 3 and 4 are likely to occupy two positions each, one in which pins 1 and 2 are coaxial and the other in which they are parallel one to the other. In the latter position, shown in FIG. 4, each of the pins 1 and 2 is located opposite the end of a duct 8, respectively 9, connected to an air suction source 10. The suction end of each of the ducts is formed of two parts 11a and 11b, respectively 12a and 12b, which extend substantially longitudinally in the duct. These two parts are fixed to each other, for example by means of screws 13 (fig. 5). Along these end parts of each of the two conduits 8 and 9 extends a flexible beat element constituted by a tongue 14, respectively 15, secured to a fixing lug 16, respectively 17 clamped between said parts d 'end 11a and 11b, respectively 12a and 12b and forming with the respective tongue a T. These beat elements are preferably cut from a rubber membrane about 0.25 mm thick. Each of the tongues 14 and 15 is preferably located near the longitudinal axis of the respective conduit in order to be able to float freely therein. The section of these conduits 8 and 9, at least in their part in which the tongue 14, respectively 15, extends, is preferably square or rectangular so that the free end of the tongue can beat against two opposite walls of the drove. Near the intake opening of the wire from each of the conduits 8 and 9, a comb 18 and 19 is fixed respectively. In each of the conduits 8 and 9 opens a channel 20 and 21 respectively, intended for the admission of secondary air. A pair of scissors formed by two steel blades 22 and 23, one of which 22 is slidably mounted relative to the "other" 23 and each of which is pierced with an opening 24 and 25 respectively, is arranged transversely to each of the suction conduits 8 and 9.

To prepare the two ends of the wire to be attached, each of them is introduced into one of the conduits 8 and 9 in which there is a slight depression created by the suction source 10. When a certain length of wire is introduced into each conduit, the pins 1 and 2 are rotated in opposite directions, so that on each of them a portion of respective wire is wound by virtue of its taking in the slot 6a, respectively 7a, formed in the head 6 , respectively 7, of the spindle 1, respectively 2. The blades 22 are then made to slide relative to the blades 23 of the two pairs of scissors, in order to cut the wires in the conduits at the level of the openings 24 and 25, so as to obtain in the upper part of each of the conduits 8 and 9 a portion of wire, one end of which is held by the respective pin.

After this preliminary operation, identical to that described in Swiss patent 623,290, the flow of air sucked through the conduits 8 and 9 is increased, in order to vibrate (flap) the tongues 14 and 15 and to exert a force of traction on the portion of wire in the conduit. The flaps of these tabs against the wires cause the fibers to dislocate in the area subjected to these flaps. As the threads are simultaneously sucked in, the dislocated fibers which no longer hold on to the strands of wire wound on pins 1 and 2 respectively, separate so that a bundle of separate fibers appears at the end of each portion of defeated yarn and can be eliminated. The rest of the connecting operations are carried out as described in the aforementioned Swiss patent. Since the actual fastener is not the subject of the present invention, these operations will not be described here and reference will be made to this patent for further details on this subject.

It should be noted that the elbow formed in each conduit 8 and 9 below the scissors 22, 23, allows, during the winding of the wire on each of the pins 1 and 2, to induce a certain distortion of the wire in the portion between the spit and the elbow. The direction of twist of the fibers in this portion must be opposite to the direction of rotation of the spindle. If, in an “open-end” yarn, an appreciable part of the fibers are not twisted, the vibrations communicated to these fibers by tabs 14 and 15, reduce their coefficient of friction, so that all the fibers which are not retained by pins 1 and 2 are eliminated by the air flow circulating in the conduits, only the dislocated fibers, retained by the pins, remaining in the conduits and forming the two ends of the wire to be twisted.

It is easy to see from the description of FIGS. 4 and 5 that each of the two assemblies, associated with the connecting device and formed by a conduit 8, respectively 9, open at both ends, of a flexible beat element 14 , respectively 15, and a source of air intake, constitutes a device implementing the method according to the present invention.

The simplicity of this device is immediately noted, insofar as only the addition of the vibrating tongues 14 and 15 is necessary, the means (1, 2; 6, 7; 6a, 7a) for holding one end of the portion of wire to be undone, the suction ducts 8, 9 and the air suction source 10 which constitutes both the means for vibrating the tongues and the means for producing the force necessary to separate and eliminate the fibers not retained, already existing in the connecting device.

It has been found that this device makes it possible to undo the wires which hitherto could not have been under the sole effect of the means normally included in such a connecting device, that is to say by means of the combs 18 and 19 and of the air flow in the conduits 8 and 9. The wire is defeated in a time not exceeding one second. It is obvious that this device is far more efficient than the two devices shown in Figs 1 and 2 respectively. It is much more reliable, much simpler to carry out and makes it possible to reduce the duration of the operation.

Figs 6 and 7 illustrate another embodiment of the pneumatic device associated with a connecting device which is the subject of EP-A1-0 029 808 to which we can refer for more details on the actual connection.

Figs 6 and 7 illustrate only one of the two oscillating supports 28, carrying a pin 29 rotatably mounted about an axis orthogonal to that of oscillation of the support 28 and provided with a head 19a split radially. The other support, not shown, is perfectly similar to support 28 and is not necessary for understanding the invention since the operation of undoing the ends of the wire to be attached is carried out symmetrically on the two supports.

The support 28 is integral with a tubular shaft 30 to which is fixed a radial arm 31 connected to the rod of a drive piston 32. An arm 33, one end of which carries a bevel gear 34, passes through the tubular shaft 30 This pinion 34 is engaged with a second bevel gear 35 wedged on the shaft of the spindle 29. A plate 36 having essentially a channel 37 and a distribution chamber 40 into which opens an intake duct 38 connected to a pressurized air source 39 is fixed on the support 28. The distribution chamber 40 has a nozzle 41 at the level of the channel 37, formed by a lip 42 forming a flow along the surface of this channel. A bypass conduit 43 connects the chamber 40 to a bore 44 in which is fixed a cone 45 whose apex is adjacent to the bottom of the channel 37 and whose axis of revolution is perpendicular to the bypass conduit 43. The air from this bypass duct, directed towards the cone 45, meets the main air flow leaving the nozzle 41 and has the role of locally expanding this current. This particular However, it is independent of the present invention.

A second tubular shaft 46, connected to the rod of a jack 47 by a radial arm 48, is pivotally mounted around the tubular shaft 30, as well as through a frame 49. This tubular shaft 46 is integral with a second radial arm 50 at the end of which is pivoted a fixing rod 51 connected to a frame 52. A second fixing rod 53, fixed to the same frame 52 is pivoted through an arm 54 parallel to the radial arm 50 and articulated to the end of another radial arm 55 secured to the tubular shaft 30, so as to form a deformable parallelogram, carrying the frame 52.

The frame 52 carries a natural rubber membrane 56 of about 0.25 mm thick, which has a longitudinal slot 56a and two transverse slots 56b delimiting two tabs 56c whose longitudinal ends are adjacent. This frame 52 is capable of occupying two positions relative to the support 28, controlled by the jack 47. In one of these positions, the frame 52 is adjacent to the plate 36 and its channel 37, in the other, shown in lines mixed in fig. 6, it is excluded.

Two suction tubes 57 and 58, connected to a suction source 59 are arranged on either side of the oscillating support 28 and its plate 36, when the support is in the position shown in FIG. 6. These tubes serve to tension the wire F through the plate 36 while the frame 52 is spaced from this plate and to pass it against the edge of the slotted head 29a of the spindle 29. The spindle 29 is rotated using the shaft 33 and the gears 34 and 35. The wire F enters the slot in the head 29a and is wound around the spindle 29. The direction of rotation of the spindle is chosen so as to untwist the portion of wire between the head 29a and the suction tube 58, as explained in detail in the aforementioned Swiss patent.

Once the wire is wound around the pin 29, the frame 52 carrying the membrane 56 is brought, by virtue of its carrying system with deformable parallelogram 50, 54 and 55, against the plate 36, so that the membrane 56 covers the wire located in channel 37. Pressurized air is then sent to the distribution chamber 40 and from this into the channel 37. The air flow passing through the channel vibrates the tabs 56c which beat the wire which is at the same time subjected to a tensile force due to the friction of the air current. The yarn breaks completely and the fibers not retained by the spindle 29 are separated and eliminated by the air stream.

It therefore appears from the description of FIGS. 6 and 7 that the device according to the invention, incorporated in the connecting device, is formed from the channel 37, the membrane 56 with its tongues 56c, and the air source under pressure (with the conduits connecting it to channel 37).

Tests have shown that this device allows you to quickly undo a wire with complete success, whatever the kind of wire. It should be noted that with certain yarns, in particular with plied yarns, it is necessary to cut the yarn before undoing it according to the process according to the present invention. This is the reason why a movable knife 60 is fixed to the plate 36 and a fixed knife 61 is fixed to the frame 49. A slight tilting of the plate 36, by the jack 32, makes it possible to carry out this operation after which the wire can be subjected to the same operation as that described above.

Generally, the vibrating elements 56c, driven in vibration by the air current, have been dimensioned to vibrate at frequencies of the order of 500 to 2000 Hz. It has been observed that it is in this frequency range with elements made of a material as flexible as rubber of the order of 0.2 to 0.3 mm thick capable of vibrating, at these frequencies, at amplitudes of the order of a millimeter, as the results are best.

Among the interesting applications of the method and of the device according to the present invention, there may be mentioned, without restriction, all the cases of reattaching the wires and in particular the preparation of the wires for this reattachment, in particular the preparation of the wires which are difficult to undo, such as "open _- end" yarns and plied yarns. This is how we can apply this process to the preparation of "open-end" wires to be attached outside or in the spinning turbine during this spinning.

Claims (7)

1. Method for preparing the end of a textile thread made of fibers intended to be retied to the end of another thread or to be introduced into a spinning device according to which one loosens a portion of this textile thread by holding it from one end and subjecting the other end to an aerodynamic action from a gaseous flow flowing in a direction away from the end held, characterized in putting into vibration a vibrating element (14, 15, 56c), transmitting these vibrations of this element to the fibers of said portion to reduce the friction coefficient between the fibers and thus undo the thread, and entraining the fibers thus separated, not retained at said end, in said gaseous flow.

2. Method according to claim 1, characterized in placing in said gaseous flow at least one flexible element with a free end (14, 15, 56c) which is held at a distance from this free end to set up into vibration by reason of the aerodynamic action exerted by the gaseous flow upon this element and in placing said portion of thread at close proximity to said free end of the flexible element for it to be subjected to the action of the vibrations of said flexible element.

3. Method according to claim 1, characterized in that one transmits to the fibers vibrations whose frequency is comprised between 500 and 1000 Hz.

4. Method according to claim 1, characterized in that one transmits to the fibers vibrations of ultrasonic frequency.

5. Device for bringing about the method according to claim 1, characterized in comprising a duct (8; 9; 58) for receiving at least one end of said portion of thread to be unthreaded, means (10) to form an air flow through this duct, means for retaining the portion of thread to be undone by one end located upstream from the portion of thread subjected to said air flow, at least one vibrating organ (14, 15, 56) located close to said thread portion, and entraining means for this vibrating organ (10, 39).

6. Device according to claim 5, characterized in that said vibrating organ is constituted by a flexible element (14, 15) fastened by one end in that part of said duct intended to accept said portion of thread to be unthreaded.

7. Device according to claim 5, characterized in that said vibrating organ is constituted by a pair of tongues (56c) obtained by providing slits in a membrane (56) ao that the free ends of these tongues are adjacent one another, and in that the membrane (56) forms at least one part of a wall of a duct (37) connected to a pressurized air source (39), this membrane being arranged so that the line of junction of the tongue ends (56c) stretches along the path of the thread in said duct (37).

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