Yarn texturing method and apparatus

Abstract

 A method of texturing a textile yarn, and apparatus for performing the method, are disclosed in which the yarn (13) is passes successively through a heating zone (15), an elongate cooling zone (16) and a false twist device (17), and is further cooled before entering the elongate cooling zone (16) by means (25) providing a flow of cooling fluid. The flow may be regulated so as to be intermittent, or in response to a yarn temperature measuring device (39) located just before the false twist device (17) and/or such that the cooling fluid, if a liquid with a boiling temperature less than that of the heated yarn (13), has evaporated before the yarn (13) enters the false twist device (17). The invention provides a shorter cooling zone (16), which with the elongate heating zone (15) preferably provide a straight yarn path, than was the case beforehand, and also provides a method of controlling the properties of the textured yarn (13) by regulation of the quantity of cooling fluid applied to the yarn (13).

Description

[0001] This invention relates to the texturing of continuous filament yarns by the false-twist method, and in particular to the cooling of such yarns in the texturing zone between the heater and the false-twist device. Sufficient cooling of the yarn is required at this stage in order that the twist memory is not removed at the de­twisting stage in the false twist device.

[0002] Conventionally in false twist texturing machines the yarn travels through a cooling zone disposed between the outlet end of the heater and the entry to the false twist device. In such cooling zone the yarn may be unsupported and cooled solely by the air through which it passes. However, since unsupported lengths of yarn are undesirable, it is conventional to pass the yarn in contact with a grooved cooling plate. Such plate may be cooled solely by the ambient air, or it may have a cooling fluid circulated through it to enhance the cooling effect and thereby reduce the length of plate required to produce sufficient yarn cooling.

[0003] As machine, and hence yarn throughput, speeds have increased the yarn path length through the heating and cooling zones has increased to allow for sufficient heating and cooling of the yarn. In consequence machine dimensions have increased undesirably, and various machine configurations have been devised in an attempt to reduce the ergonomic disadvantages of large machines. From the twist insertion point of view it is preferable that the yarn travels in a substantially straight line throughout the texturing, i.e. heating and cooling, zone. It is therefore essential to minimise either or both of the heating zone length and the cooling zone length in order to maintain the machine size within acceptable limits.

[0004] In the case of the false twisting by means of intercrossing endless belts, between which the yarn is passed in the crossing region, it is known to apply a liquid to the yarn immediately prior to its passage between the belts. This liquid application, whilst providing a cooling effect on the yarn, is primarily for lubrication and cooling of the belts so that undue heat generation by, and excessive wear of, the belts is avoided. Such a process is described in British Patent No 2032971 and US Patent No 4362011. In the apparatus described in latter patent, the water application device is disposed after an elongate cooling plate, close to the endless belts false twisting device. Thus no significant reduction in cooling zone length is achieved by such means.

[0005] It is an object of the present invention to provide a method of, and apparatus for, the texturing of textile yarn by false twisting, wherein the length of the cooling zone required to produce sufficient cooling of the yarn is less than that required heretofore. It is also an object of the present invention to provide a method whereby the cooling of the yarn may be accurately controlled in order to produce a yarn of desired bulk characteristics suitable for the production of fabrics having desired shrinkage characteristics.

[0006] The invention provides a method of texturing a textile yarn comprising passing the yarn successively through a heating zone, an elongate cooling zone and a false-twist device, and, at the upstream end of the cooling zone, subjecting the heated yarn to a flow of a cooling fluid to assist in cooling the yarn as it passes through the cooling zone. The yarn may be subjected to a plurality of such flows as it passes from the heating zone to the cooling zone. The method may also comprise measuring a yarn parameter at a location downstream of the cooling zone and regulating the flow of the cooling fluid in response to the yarn parameter measurement, which may be yarn temperature. The yarn may be subjected to a flow of a cooling liquid having a boiling temperature which is less than that to which the yarn is heated in the heating zone, in which case the flow of the cooling liquid may be regulated whereby substantially all of the cooling liquid carried by the yarn into the cooling zone has evaporated prior to entry of the yarn into the false twist device. The method may comprise intermittently varying the subjection of the heated yarn to the flow of cooling fluid.

[0007] The invention also provides apparatus for texturing a textile yarn comprising, an elongate heating means, an elongate cooling means and a false-twist device disposed successively along a yarn path defined thereby, and, disposed at the upstream end of the elongate cooling means, further cooling means operable to subject the heated yarn to a flow of a cooling fluid. A plurality of such further cooling means may be provided along the yarn path between the heating means and the elongate cooling means.

[0008] The further cooling means may comprise regulating means operable to control the rate of flow of cooling fluid to the heated yarn, and the regulating means may be responsive to the yarn parameter measuring means disposed downstream of the cooling zone. The yarn parameter measuring means may be operable to provide a signal proportional to a measured parameter of the yarn at the location of the sensing means. The parameter may be temperature.

[0009] The further cooling means may comprise a guide defining a guide path contacted by the yarn as it passes from the heating means to the elongate cooling means, the guide having an aperture therein communicating with the guide path and through which the cooling fluid passes onto the yarn.

[0010] Preferably the cooling fluid is a liquid having a boiling temperature of less than that to which the yarn is heated by the heating means. The liquid may be water. The regulator may be operable to regulate the flow of the cooling liquid to the yarn whereby substantially all of the cooling liquid carried by the yarn into the cooling zone has evaporated prior to the entry of the yarn into the false-twist device.

[0011] The false-twist device may comprise three sets of overlapping discs rotating in the same direction about parallel axes located at the corners of an equilateral triangle, in frictional contact with the peripheries of which discs the yarn is passed. The elongate heating means and/or the elongate cooling means may comprise a plate having a groove extending therealong, and the elongate heating means and the elongate cooling means may define a substantially straight yarn path.

[0012] The invention will now be further described with reference to the accompanying drawings in which

Fig 1 is a yarn path diagram of a texturing machine incorporating the present invention

Fig 2 is a diagrammatic cross-sectional view of one embodiment of further cooling means of the machine of Fig 1 and

Fig 3 illustrates the use of several of the further cooling means of Fig 2.

[0013] Referring now to Fig 1 there is shown a texturing machine 10 comprising a creel 11 containing supply packages 12 of yarn 13, and for each yarn 13 a first feed means 14, an elongate heating means 15, an elongate cooling means 16, a false-twist device 17, a second feed means 18 and a wind-­up means 19 producing a package 20 of textured yarn. With the high yarn throughput speeds currently attainable it is necessary to have relatively long heaters 15 and cooling means 16 in order that the required heating and subsequent cooling of the yarn 13 is achieved. In the embodiment shown, the elongate heating means 15 and the elongate cooling means 16 are substantially in alignment so as to provide a substantially straight yarn path to the false-twist device 17 from a yarn guide 21, adjacent the entry to the heating means 15. Such an arrangement has the advantage that good twist propogation, from the false-­twist device 17 through the heating zone 15 to the twist-­stopping yarn guide 21, is achieved. However the arrangement has the disadvantages that the overall machine height is excessive and the entry point to the heater 15 is not within the reach of an operator for threading purposes. This latter problem necessitates the mounting of the yarn guide 21 on a sledge 23 which is movable along a sledge track 22 between a lower threading position and an upper operating position by means of an elongate handle or wand 24. Overcoming these disadvantages by "bending" the yarn path between the heater 15 and the cooling means 16 introduces the disadvantage that twist propogation from the twist device 17 back to the heater 15 is prejudiced, leading to reduced crimp quality and regularity in comparison with those attainable with the straight yarn path arrangement.

[0014] To reduce the dimensional effects of the long heating and cooling zones 15, 16, particularly with the straight yarn path arrangement as shown in Fig 1, the apparatus of the present invention provides a further cooling means 25 disposed between the heating means 15 and the cooling means 16. The heating means 15 may be any conventional means such as an elongate plate having a yarn path groove extending therealong and heated either electrically or by a vapour-phase heating fluid. The cooling means 16 may also be an elongate plate having a yarn path groove extending therealong. The further cooling means 25 comprises a manifold 26 extending lengthwise of the machine 10 and fed with water from a supply device 27 as shown in Fig 2. The water supply device 27 comprises a header tank 28 from which the water passes along supply pipe 29 to the manifold 26. The head of water in the header tank 28 can be adjusted as desired by rotation of a weir tube 29, using adjusting wheel 37, to align one of a plurality of holes 30, arranged spirally around the tube 29, with an elongate slot extending along a co-axial tube which communicates through an overflow pipe 31 with a reservoir 32. The water supply in the header tank 28 is maintained by pumping water from the reservoir 32 back into the header tank 28 using pump 33. The water in the manifold 26 travels the length of the machine 10. A each yarn processing station a capilliary tube 34 extends across the manifold 26 and communicates with a groove 36 in a yarn guide 35. The manifold 26 is of such a large diameter having regard to the rate of water flow therealong that pressure losses along the length of the machine are negligible. In consequence the pressure creating flow along each capilliary tube 34 is substantially equal to the head set at the header tank 28. The water flow onto the yarn 13 in the guide 35 is therefore accurately controlled. Excess water, and water flowing when no yarn 13 is present at a particular yarn processing station, is collected in tray 38 and returned to the reservoir 32 or to waste.

[0015] The initial uptake of cold water by the heated yarn 13 as it exits the heater 15 in its hottest state and passes in connect with the yarn guide groove 36, has a maximum cooling effect on the yarn 13. In consequence the length of the cooling plate 16 may be less than would be required if no cooling fluid is used. In addition, since the yarn 13 as it exits from the heater 15 is in a plastic state at a considerably higher temperature than the boiling temperature of water, rapid evaporation of the water will occur by extracting the latent heat of evaporation from the yarn 13. This further cooling of the yarn 13 enables a further reduction in the length of the cooling plate 16 required to produce the necessary overall amount of cooling of the yarn 13 before it enters the false-twist device 17.

[0016] If, as shown in Fig 1, the false-twist device 17 comprises three sets of overlapping discs rotating in the same direction about parallel axes located at the corners of an equilateral triangle, the amount of water applied to the yarn 13 may be regulated so that substantially no water remains on the yarn 13 as it enters the false-twist device 17, thereby ensuring good twist inducing frictional contact between the yarn 13 and the discs of device 17. However, if a crossed endless belts type of false-twist device 17 is used the amount of water applied to the yarn 13 may be regulated so that the yarn 13 is still wet as it enters the false-twist device 17, and inter-belt friction, heat generation and wear are minimised.

[0017] In addition to the advantages associated with a reduction in the length of the cooling zone 16, the present invention provides a further advantage over previously known arrangements. As described above the apparatus shown in Fig 1 is capable of producing high bulk stretch yarns, and with the addition of a second heater between the second feed means 18 and the take-up means 19, high bulk set yarn, to produce fabrics having appropriate characteristics. However for certain textile applications it is desirable to produce fabrics having differing characteristics, for example a high residual shrinkage, from those produced from conventionally textured yarns. The yarns for such alternative fabrics can be produced by de-twisting the yarn at a higher temperature than is conventional when producing normal high bulk textured yarn, but cannot readily be produced on the conventional texturing apparatus. In the case of the present invention however such alternative fabric producing yarn can be readily produced, by reducing the amount of cooling fluid applied to the yarn 13, thereby providing that the yarn 13 enters the false-twist device 17 at a higher temperature than is required when producing conventional high bulk textured yarn. The desired fabric characteristics can be readily obtained by appropriate regulation of the amount of water applied to the yarn 13 to vary the temperature of the yarn 13 as it is de-twisted in the false-twist device 17. For this purpose a temperature sensor 39 may be provided between the cooling plate 16 and the false-twist device 17, as shown in Fig 1, and this sensor 39 may be coupled with means 40 (see Fig 2) for altering the head in the header tank 28 and hence the rate of application of cooling fluid to the yarn 13. The invention therefore provides controlled cooling of the yarn 13, leading to the production from the resulting textured yarn of textile fabrics of desired characteristics.

[0018] Although water is the preferred cooling fluid for reasons of cost and evaporation heat loss, other fluids, eg high pressure air, may be used if desired.

[0019] In the event that an appreciable quantity of water or other cooling fluid is required, thereby minimising the length of the cooling means 16, more than one further cooling means 25 may be provided as shown in Fig 3. Such an arrangement provides for more effective and efficient fluid uptake by the yarn 13 than would be the case if an attempt is made to apply all of the required cooling fluid to the yarn 13 at a single location.

[0020] If desired the cooling fluid may be applied to the yarn in a pulsating manner, thereby to create varying texture/dye uptake effects along the length of the yarn. This may be achieved by controlling the rate of flow of cooling fluid in a pulsating or intermittent manner using head regulating means 40, or by intermittently moving the yarn in and out of the path of the flow of cooling fluid, eg by rotating an eccentric guide 41 (fig 2).

[0021] A further advantage of the present invention arises from the cleansing effect on the yarn by water application so as to eliminate or at least substantially reduce the amount of spin-finish oil on the yarn as it enters the false twist device. This avoids or minimises the possible chemical attack by the spin finish oil on the surfaces of the friction discs, particularly if the latter are polyurethane. Also, as a consequence of the cleansing of the yarn,polymer which is ground thereoff by the hard twisting discs cannot combine with the spin finish to create a sticky deposit on the discs and thereby reduce the performance of the twist unit.

Claims

1. A method of texturing a textile yarn comprising passing the yarn successively through a heating zone, an elongate cooling zone and a false twist device, characterised by subjecting the heated yarn (13) at the upstream end of the cooling zone (16) to a flow of cooling fluid to assist in cooling the yarn (13) as it passes through the cooling zone (16).

2. A method according to claim 1, characterised by measuring a yarn parameter at a location (39) downstream of the cooling zone (16) and regulating the flow of the cooling fluid in response to the yarn parameter measurement.

3. A method according to claim 1 or claim 2, characterised by subjecting the yarn (13) to a flow of cooling liquid having a boiling temperature which is less than that to which the yarn (13) is heated in the heating zone (15), and regulating the flow of the cooling liquid whereby substantially all of the cooling liquid carried by the yarn (13) into the cooling zone (16) has evaporated prior to the entry of the yarn (13) into the false twist device (17).

4. Apparatus for texturing a textile yarn comprising a heating means, an elongate cooling means and a false twist device disposed successively along a yarn path defined thereby, characterised in that there is disposed at the upstream end and of the elongate cooling means (16), further cooling means (25) operable to subject the heated yarn (13) to a flow of cooling liquid.

5. Apparatus according to claim 4, characterised in that a plurality of such further cooling means (25) are disposed along the yarn path between the heating means (15) and the elongate cooling means (16).

6. Apparatus according to claim 4 or claim 5, characterised in that a regulating means (28, 29, 37, 40) is provided to regulate the flow of the cooling fluid.

7. Apparatus according to claim 6, characterised in that a yarn parameter measuring means (39) is disposed at a location downstream of the elongate cooling means (16), and the regulating means(28, 29, 37) is operable to regulate the flow of the cooling fluid in response to the yarn parameter measuring means (39).

8. Apparatus according to any one of claims 4 to 7, characterised in that the further cooling means (25) is operable to subject the heated yarn (13) to a flow of a cooling liquid having a boiling temperature which is less than that to which the yarn (13) is heated by the heating means (15).

9. Apparatus according to any one of claims 4 to 8 characterised in that the or each further cooling means (25) comprises a guide (35) defining a guide path contacted by the yarn (13) as it passes from the heating means (15) to the elongate cooling means (16), and in that the or each guide (35) has an aperture (34) therein communicating with the guide path and through which the cooling fluid passes onto the yarn (13).

10. Apparatus according to any one of claims 4 to 9 characterised in that the heating means (15) is elongate and together with the elongate cooling means (16) defines a substantially straight yarn path.

Drawing