GB2051898A - A method and apparatus for producing an air-textured looped composite yarn - Google Patents

Abstract

Two fibre bundles 1 and 8 are supplied in excess, preferably at different supply rates, and are passed from above vertically downwards through an air jet (7) in which they are mixed together with the simultaneous formation of individual capillary loops. The fibre bundles are tension-free as they pass through the air jet due to the air-textured looped yarn (12) which emerges vertically from the air-jet being carried from below vertically upwards in a freely oscillating thread loop S via a tension building device 13 to a reel device 5, 15 which is laterally offset relative to the air jet. <IMAGE>

Description

SPECIFICATION A method and apparatus for producing an airtextured looped yarn The present invention relates to a method for producing an air-textured looped yarn from at least two continuous fibre bundles which with excess supply are passed downwards from above in a substantially vertical direction through an air jet operated by compressed air, optionally at different excess supply rates, in which air-jet they are mixed together with the simuitaneous formation of individual capillary loops, whereupon the air-textured looped yarn is conveyed to a reeling device which is in a laterally removed position with respect to the air jet. The invention also relates to an apparatus for implementing this method.

A typical method is known for example from Japanese laid open specification No. 77,049,367 (application date: 1 5.10.75; date laid open to public inspection: 20.4.77). In this case, a falsetwist-textured continuous fibre bundle and another multifilament yarn are mixed together in an air jet operated by compressed air, whereby the capillaries of the false-twist-textured continuous fibre bundle are incolporated at least partially in the form of small kinks or loops. These small loops which project out of the surface of the air textured looped yarn generally lead to an improvement in the appearance of the cloth and feel of the sheet structures, produced from these yarns.

In recent years the technology for the production of air textured looped yarns which is also termed air-texturing, jet-texturing or air-blast texturing, has been continuously developed further, that is both for texturing individual continuous fibre bundles as well as for mixing and texturing two or more continuous fibre bundles, whereby interesting fancy yarns may also be produced by varying the rate of feed of the individual components into the air jet. The following papers provide a good survey on the prior art of this technology: "Entwicklung einer Duse fur das Lufttexturieren" by U. LIEBSCHER/K.

STEGERER/G. HEBENSTREIT in Wiss. Z.d. Techn.

Hochsch. Karl-Marx-Stadt 11(1969), H.1., pages 79-93, "Die Texturierung von Chemie-fäden im Luftstrom" by J. W. LÜNENSGHLOSS/J. G. HELLIS in TEXTIL-PRAXIS 1969, August, Pages 51 5- 520 and Luftblastexturieren von Polyester- and anderen Filarnentgarnen" byG. BREHM in chemiefaser/textile-industrie, June 1 978, pages 552-558 and August 1978, pages 706-708.

The fact emerges from these papers that the air-jet texturing of several components having a varying shrinking or dyeing behaviour depends particularly on the regularity of the loop formation (i.e. regular size and thickness of the loop) and on a good mixing of the loops. Essential parameters for these characteristics are firstly the pressure of the blast which, at approximately from 8 to 10 bars, must be comparatively high, and secondly, the thread velocity which must not be too high, generally with a maximum limit of from 300 to 400 m/min. Atmospheric pressure and thread velocity must not be too high because there is a danger of mechanical damage being caused, particularly where fine-capillary yarns and yarns which have a low tensile strength are concerned.

The consequence of this is fibre fly or the formation of slubs.

The invention is based on the object of providing a method of producing an air-textured looped yarn from at least two continuous fibre bundles, which allows an intense and regular loop formation and intermixing of the loops, while carefully treating the thread material, without being directed to use the familiar high atmospheric pressures or being restricted to the familiar low thread velocities.

According to the present invention there is provided a method for producing an air-textured looped yarn from at least two continuous fibre bundles which with excess supply are passed from above through an air-jet operated by compressed air in a substantially vertically downward direction, in which air jet they are mixed together with the simultaneous formation of individual capillary loops, whereupon the air-textured looped yarn is conveyed to a reeling device which is in a laterally removed position with respect to the air jet, wherein the continuous fibre bundles are free from tension while passing through the air jet and the air-textured looped yarn blown out in a vertical direction from the air jet proceeds upwardly from below in a freely oscillating thread loop to be reeled.

It has been found that individual capillaries are only regularly and intensively blown when they are completely free of tensile stress during their passage through the jet and are carried out of the jet by a blast of gas e.g air. Only when a freely oscillating thread loop is formed can a regular and reliably reproducible effect be obtained. The freely oscillating thread loop may only be produced when the yarn components to be blown pass downwards through the air jet from above and proceed upwards to be reeled from below.The transportation of the fibre bundles out of the air jet by means of the blowing medium in a vertical upward direction from below or in a horizontal direction, as known for example from German Offenlegungsschrift No. 1,410,415 or British Patent No. 828,641, does not lead to the formation of a freely oscillating thread loop, on account of the absence of control opportunities in respect of a free loop formation and also due to the formation of kinks arising thereby, nor does the removal of an air-textured looped yarn which is blown downwards out of the air jet towards the reeling device in a horizontal direction or in a vertical downward direction from above as known from Japanese Patent No. 7,215,547 (date of application: 1.7.67; date laid open to public inspection: 9.5.72) or Japanese laid open application No. 77,049,367.Finally, the airtextured looped yarn must not say to such an extent between the air jet and the winding system as known from Japanese laid open Application No.

77,042,955, that the thread run has a more or less stamped out kink.

As it is insignificant which constructional measures (geometry of the air-jet, arrangement of the jet in relation to the reeling device) are used to produce the freely oscillating thread loop, these factors which do not influence the continuous operational costs may be coordinated so exactly with a specific yarn that where there are high working velocities, a minimum of air consumption may be set. Therefore, conventional textile yarns may be blown intensively and regularly at pressures of 3 bars or less at drawing-off rates of 800 m/min or more. In this careful treatment, the yarn is not damaged mechanically and the textile date is not impaired.

A further levelling in the texturing effect may be produced when the continuous fibre bundles which are fed into the air jet are conveyed separately until they enter into the air jet.

In order to effect the build-up of the yarn tension which is required for reeling, conventional thread brakes may be provided below the reeling device. In this case, it is preferably to convey the air-textured looped yarn to the reeling device via a device through which it passes upwards from below in order to build up the thread tension.

The method according to the invention is suitable for the treatment of ali currently produced yarns in the fine, medium and coarse titre range (up to for example 3000 dtex for the furnishing fabric range), whereby yarns of a different material e.g. made of polyesters, polyarnides, polyurethanes, polyolefins, rayon, cellulose acetate etc. may be blended together.

If more than two components are blown together, then it is advisable to feed the second, third etc. components at respectively the same excess delivery. Thereby, it is essential to separate all the component threads up to the blowing point.

Another object of the invention is to provide an apparatus for implementing in a preferred manner the method of the invention.

Thus, according to a further aspect of the present invention there is provided a methodfor producing an air-textured looped yarn substantially as herein described with reference to and as illustrated in the accompanying drawing.

The specific air jet provides a transport effect, i.e. it blows the forming air-textured looped yarn out of the thread guide groove vertically downwards. The deflection member below the reeling device also promotes the formation of the freely oscillating thread loop.

In a preferred embodiment of the apparatus, a thread dividing pin is positioned upstream of the air jet at a spacing of approximately from 5 to 20 mm. The effect of this dividing pin is that the threads 'are blown by the air in the jet only in the thread run direction and consequently, particularly regular loops are produced. In the absence of a dividing pin, preliminary blastings occur, as a result of which loops of irregular size are produced. The spacing of the dividing pin from the air-jet is substantially dependent on its diameter.

Another preferred embodiment provides that the delivery devices for the different continuous fibre bundles are designed as conically step-wise offset appendage of the friction roller of a reeling device.

A preferred embodiment of the present invention will be described by way of example with reference to the accompanying drawing in which the embodiment is shown schematically.

From a bobbin 1, a continuous fibre bundle 2 is conveyed to a conical shoulder 4' of an appendage 4 of a friction roller 5 via a thread guide 3. The continuous fibre bundle passes over the shoulder 4r twice via a runover roller 6 and then proceeds to an air jet 7. From a second bobbin 8, a second continuous fibre bundle 9 runs via a thread guide 10 to another conical shoulder 4" of the appendage 4 and proceeds to the air jet 7 at a slower rate than the first continuous fibre bundle 2 due to the smaller diameter of this other shoulder 4" with respect to the shoulder 4'. Both continuous fibre bundles are separated by a thread dividing pin 1-1 just until they enter into the thread guide groove 7' of the air jet 7 which is supplied with compressed air "A" via a pipe.

An air-textured looped yarn 12 indicated by chain dotted line proceeds to the bobbin 1 5 in a freely oscillating thread loop S via a friction body 13, which acts as a deflection member and as a tension building device, vertically upwards by means of a thread guide 14 which controls the wind.on tension and thus also the size of the thread loop.

The position and shape of the freely oscillating thread loop is unimportant The loop may also change during operation, compare S' vindicated by dashed line).

Claims (9)

1. A method for producing an air-textured looped yarn from at least two continuous fibre bundles which with excess supply are passed from aboverthrough an air-jet operated by compressed air in a substantially vertically downwardxdirection, in which air jet they are mixed together with the simu!taneous formation of individual capillary loops, whereupon the air-textured looped yarn is conveyed to a reeling device which is in a laterally removed position with respect to the air jet, wherein the continuous fibre bundles are free from tension while passing through the air jet and the air-textured looped yarn blown out in a vertical direction from the air jet proceeds upwardly from below in a freely oscillating thread loop to be reeled.

2. A method according to claim 1, wherein the fibre bundles have different excess supply rates.

3. A method according to claim 1 or 2, wherein the continuous fibre bundles are conveyed separately until they enter the air jet.

4. A method according to claim 1,2 or 3, wherein the air-textured looped yarn is convened to a reeling device via a tension building device,

5. A method for producing an air-textured looped yarn substantially as herein described with reference to and as iUustrated in the accompanying drawing.

6. An apparatus for producing an air-textured iooped;yarn from at least two continuous fibre bundles, comprising delivery devices for the different continuous fibre bundles, an air jet having a thread guide groove which extends in a substantiaily vertical direction and has a larger flow cross section on, the thread outlet side than an the thread inlet side, a reeling device which is in å iateraiiy removed position with respect to the air jet, and a thread deflection member the thread ,guida.surface of which is positioned vertically below the reeling device on the thread delivery side.

7. An apparatus according to claim 6, further comprising a thread dividing pin located upstream of the air jet at a spacing of approximately from 5 to 20 mm.

8. An apparatus according to claim 6 or 7, wherein the respective delivery devices for the continuous fibre bundles are appendages of a friction roller of the reeling device which are offset in conically stepwise fashion.

9. An apparatus for producing an air-textured looped yarn, substantially as herein described with reference to and as illustrated in the accompanying drawing.