GB2136462A - Yarn handling process and apparatus - Google Patents

Abstract

A yarn store, for example for use with splicing of yarn delivered from a friction spinner, comprises a plurality of passages (2a, 2b, 2c, etc.) into which a length of yarn may be biased by the effect of suction in a plenum chamber (4). The application of suction is sequenced by a slide valve (6) which progressively opens the array of suction passages to the plenum chamber (4) whereby a first level of suction is applied to suck in the yarn and a weaker level of suction is then applied to back-tension the yarn. <IMAGE>

Description

SPECIFICATION Yarn handling process and apparatus The present invention relates to yarn handling and in particular to a process and apparatus for facilitating joining of two lengths of yarn "on-the-ily".

There are various known methods of joining two lengths of yarn, such as splicing, knotting and glueing, and many other techniques of less widespread application. The task of joining two lengths of yarn is made more complicated when this is to be carried out "on-thefly" because there is usually one of the lengths which is stationary and attached to a winder, and another length which is being delivered continuously and is therefore moving. The longer the time taken by the joining technique, the greater the amount of the second length which has been delivered during the joining operation, and consequently the more likelihood there is of snarling when the yarn winder takes up.

One method, used hitherto in continuous filament yarn handling, employs a suction gun or aspirator which can be used to entrain a loose end, thereby facilitating piecing up.

However, where yarn is to be joined, the scope for yarn storage using such an aspirator is very limited because the free end of the yarn length must be used for the joining operation and if the "second length" is still being drawn into the aspirator during its continued delivery then there is a considerable risk of tangling and snarling of the yarn when eventually the join has been made and the stored yarn is wound up.

It is an object of the present invention to provide for the handling of yarn by storing a length of yarn "on-the-fly" with improved storage capacity. Such improved capacity is, for example, necessary when the delivered yarn is being produced by high speed spinning of staple yarn.

Accordingly a first aspect of the present invention provides a process of handling a yarn end "on-the-fly" comprising introducing the yarn into a plurality of yarn store locations subject to means entraining the yarn to enter the store locations, and subsequently progressively extracting the yarn from the various store locations and feeding it onward.

A second aspect of the invention provides a process of handling a yarn end "on-the-fly" comprising introducing the yarn into a plurality of yarn store passages subject to suction applied at first ends of the passsages to entrain the yarn into the second ends of the passages, and subsequently progressively extracting the yarn from the various yarn store passages and feeding it onward, wherein a first yarn-attracting level of suction is applied sequentially to various of the yarn store passages and a weaker yarn retaining level of suction is applied to each of said passages as the yarn attracting suction level in that passage ceases, whereby once charged with yarn each passage holds its stored yarn to exert a back tension during yarn extraction.

A third aspect of the present invention provides apparatus for handling yarn, comprising a yarn store having a plurality of yarn store locations, and means for biasing a continuous length of yarn into said yarn store locations to build up a respective serially interconnected reservoir length in each of said yarn store locations.

A fourth aspect of the invention provides apparatus for handling yarn, comprising a plurality of yarn store passages each open at one end to a source of suction and at the other end for yarn introduction and means to apply a first level of suction to the yarn store passages in sequence and to apply a weaker suction level to each such passage as the first suction level ceases.

In order that the present invention may more readily be understood the following description is given, merely by way of example, with reference to one embodiment of yarn handling apparatus in accordance with the present invention, illustrated in the accompanying drawings in which: Figure 1 is an enlarged very schematic cross-section of a yarn store in accordance with the present invention during build-up of a first yarn reservoir length to form part of a yarn reservoir therein; and Figure 2 is a view, similar to Fig. 1, but showing a further stage during the build-up of a yarn reservoir in the apparatus.

Fig. 1 shows a yarn store body 1 as comprising a plurality of yarn store passages 2a, 2b, 2c, 2d, 2e, 2fand 2g, each having an outer end open to a yarn path to be followed by a yarn 3 and having an inner end which opens into a suction plenum chamber 4 communicated by way of a suction passage 5 to a suitable source of suction, not shown. A slide valve 6 has a main aperture 6a, able to open the bottom of each of the yarn store passages 2a, 2b etc., in turn, to the suction plenum chamber.

Initially, when yarn is to be joined, the free end 3' of the yarn 3 shown in Fig. 1 is introduced to a yarn joining device (for example a yarn splicer), the yarn is held by a clamp 7, and a part of the yarn is allowed to be positioned over the first yarn store passage 2a as the yarn 3 is still being delivered, for example from a friction spinner. With the slide valve 6 in its Fig. 1 position the first yarn store passage 2a is subject to suction and a loop 3a of yarn builds up in the passage 2a.

At a suitable subsequent instant, when the yarn reservoir length 3a has built up so that it occupies substantially the entire length of the first yarn store passage 2a, the slide valve 6 will have moved across far enough for the main aperture 6a to clear the bottom of the passage 2a and to open the next yarn store passage 2b to cause a similar build-up of a yarn reservoir length therein.

As shown in the drawings, the slide valve 6 has a foraminous area, penetrated by subsidiary apertures 6b, immediately behind the main aperture 6a. Thus as the main aperture moves on to open a subsequent yarn store passage 2b, 2c etc. to the full "yarn attracting" suction of plenum chamber 4, the previously charged yarn store passage(s) 2a, 2b etc. are subjected to attenuated "yarn retaining" suction by way of the flow throttling subsidiary apertures 6b of the foraminous region of the slide valve.

This procedure is carried out successively for the individual yarn store passages 2a, 2b, 2c, etc., until the Fig. 2 position is reached where the yarn length 3d in the yarn store passage 2d is in the process of building-up in the yarn store passage 2d and the previous passages 2a, 2b and 2 c have each been closed off by the slide valve 6.

In order to generate a desired degree of yarn retaining" influence in the charged yarn store locations (e.g. 2a, 2b, 2c when the slide valve main aperture 6a is in the Fig. 2 position) the distribution and/or cross-section of the subsidiary apertures 6b will be carefully related to the cross-section of the main aperture 6a and/or to the suction available in the plenum chamber 4.

In the drawings each of the yarn reservoir lengths 3a, 3b, 3c, etc. is shown schematically as one of several serially interconnected simple U-shaped loops. However, in practice the twist in spun yarn will cause the loops 3a, 3b, 3c, etc., to twist; this is acceptable provided the length of yarn forming any one yarn reservoir loop is limited so that smooth takeup of the yarn later from that yarn store passage 2a, 2b, 2c, etc, is possible without yarn snarling.

Ideally the free end 3' of the yarn will have been spliced to the stationary length of yarn before the final yarn store passage (in this case 29) has been filled and closed off, and consequently there will be ample capacity for a yarn splicing operation. Of course, the number of yarn loops built up will be a function of (a) the depth of each of the yarn store passages 2a, 2b, 2e etc., (b) the running speed of the yarn length 3, and (c) the time taken to complete the splicing operation.

As mentioned above, the apparatus illustrated in Figs. 1 and 2 is purely schematically shown and does not illustrate such features as rounded corners to avoid snagging of the yarns, and is also not to scale in that there may in practice be many more than the seven yarn store passages 2a-2g shown, and the ratio of the length: width of each of these passages may be much greater than illustrated. However, these and other such refinements can be incorporated in the apparatus without departing from the scope of the inven

Claims (14)

tion as claimed. If desired, other forms of sequencing means may be employed, such as arranging the array of yarn store locations 2a, 2b, 2c. . . 2g transversely (preferably obliquely) of the yarn path and shifting the yarn length 3 into register with another of the locations when a first location has been charged with yarn. It is considered advantageous for there to be some "yarn retaining" influence at a charged yarn store location, for example due to the preferred "yarn retaining" suction through subsidiary apertures 6b, or due to friction of the yarn over the run of each yarn store passage 2a, 2b, 2c, etc. or possibly due to leakage suction effects, as this "yarn retaining" influence gives rise to more satisfactory yarn take-up on resumption of winding. This enables smooth take-up of stored yarn, for example at the yarn speeds encountered during high speed spinning process such as rotor spinning, friction spinning, and jet spinning. As an alternative to the suction-induced loading of the yarn store locations in the apparatus illustrated in Figs. 1 and 2, it is alternatively possible for the yarn to be biased into each store location by a mechanical device. For example the yarn store locations may be defined as separate planes in space but generally coincident with a path of travel of a respective one of a set of guide wires. There may, for example, be two sets of guide wires each disposed along a respective side of the yarn path, and the yarn store may be loaded simply by causing the various yarn guide wires to cross the yarn path and to entrain a corresponding loop of yarn thereon. Preferably the crossing of the yarn path is carried out by sequential movement of the individual wires starting from a first end of the two sets, and subsequent release of the yarn may be by return of the individual yarn guide wires to their starting positions in the same sequence, again crossing back over the yarn path. As in the embodiment of Figs. 1 and 2, a yarn clamp may be provided. Any other means of loading separate yarn store locations, preferably sequentially, may be used within the scope of the present invention. CLAIMS

1. A process of handling a yarn end "onthe-fly" comprising introducing the yarn into a plurality of yarn store locations subject to means entraining the yarn to enter the store locations, and subsequently progressively extracting the yarn from the various store locations and feeding it onward.

2. A process according to claim 1, wherein each of the store locations is a pas sage open at one end to a source of vacuum and at the other end to a yarn path from which the yarn is introduced into that passage.

3. A process according to any one of the preceding claims, wherein the yarn store locations are changed sequentially with the yarn, and are discharged of yarn sequentially.

4. A process of handling a yarn end "onthe-fly" comprising introducing the yarn into a plurality of yarn store passages subject to suction applied at first ends of the passages to entrain the yarn into the second ends of the passages, and subsequently progressively extracting the yarn from the various yarn store passages and feeding it onward, wherein a first yarn-attracting level of suction is applied sequentially to various of the yarn store passages and a weaker yarn retaining level of suction is applied to each of said passages as the yarn attracting suction level in that passage ceases, whereby once charged with yarn each passage holds its stored yarn to exert a back tension during yarn extraction.

5. A process according to claim 3 or 4, wherein the sequence of discharging is the same as the sequence in which the yarn store locations were charged.

6. A process according to any one of the preceding claims, comprising the further step of joining the yarn to a second length of yarn during a storing operation, and subsequently extracting the yarn by winding-up the second length of yarn and thereby entraining the first length of yarn with it.

7. A process of yarn handling, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

8. Apparatus for handling yarn, comprising a yarn store having a plurality of yarn store locations, and means for biasing a continuous length of yarn into said yarn store locations to build up a respective serially interconnected reservior length in each of said yarn store locations.

9. Apparatus according to claim 8, wherein said biasing means operates sequentially in co-operation with the yarn store locations to urge the formation of yarn reservoir lengths in the yarn store locations in sequence.

10. Apparatus according to claim 8 or 9, wherein each of the yarn store locations comprises a passage having a first end adapted to be connected to a source of suction and a second end open to a yarn path from which said yarn resevoir length is built up, the suction serving as the biasing means.

11. Apparatus according to claim 1 0, when appendant to claim 9, and further including means controlling sequencing of the application of suction to the various yarn store locations.

12. Apparatus for handling yarn, comprising a plurality of yarn store passages each open at one end to a source of suction and at the other end for yarn introduction, and means to apply a first level of suction to the yarn store passages in sequence and to apply a weaker suction level to each such passage as the first suction level ceases.

1 3. Apparatus according to claim 11 or 12, wherein the suction sequencing means comprise a slide valve having an opening adapted to open sequentially the first ends of the yarn store passages to a suction plenum chamber and having a suction attenuating region which communicates each yarn store passage to the plenum chamber after said opening has passed over the end of that yarn store passage.

14. Apparatus according to claim 8 or 9, wherein each yarn store location comprises the space bordering the path of movement of a respective yarn guide wire across the yarn path, there being two sets of said yarn guide wires with each set disposed along a respective side of the yarn path.

1 5. Yarn handling apparatus according to claim 8 and substantially as hereinbefore de scribe.

1 6. Yarn handling apparatus substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.

1 7. Yarn which has been subjected to the process of any one of claims 1 to 7.