GB2324540A

GB2324540A - Pneumatic yarn spinning

Info

Publication number: GB2324540A
Application number: GB9708273A
Authority: GB
Inventors: Ryszard Jozwicki; Czeslaw Radom; Wieslaw Stasiak
Original assignee: Instytut Wlokiennictwa; Inst Wlokiennictwa
Current assignee: Instytut Wlokiennictwa; Inst Wlokiennictwa
Priority date: 1997-04-24
Filing date: 1997-04-24
Publication date: 1998-10-28
Anticipated expiration: 2017-04-24
Also published as: GB9708273D0; GB2324540B

Abstract

A pneumatic spinning method for the production of yarn comprises providing a continuous stream of a plurality of bundles of fibres (1a,1b); applying an initial twist to at least one of said bundles in a first direction; thereafter causing said plurality of bundles to converge whereby they are mutually juxtaposed; and applying a fluid vortex induced torsional moment to the juxtaposed fibres to induce a final twist in said bundles in a second twist direction which is the reverse of the first direction.

Description

Method and device for yarn production This invention relates to the field of spinning yarn and in particular devices for, and methods of, spinning.

EP-B-0,094,011 discloses a method and a device for producing yarn by the use of a pneumatic technique based on winding side fibres, which lie on the surface of the yarn, around the core of the yarn, which core consists of substantially parallely arranged fibres. The winding of the side fibres can be achieved with the use of a set of two transit air chambers that are furnished with contiguous sets of nozzles of opposite air inlet direction. The yarn thereby produced typically has low strength and high rigidity, and this limits the range of its uses. Moreover, only fine yarn up to 25 tex can be produced from combed long-fibre cotton by the use of this method.

Japanese patent publication No. 03193923A discloses a method and a device for producing yarn by a pneumatic technique which is based on winding a small amount of fibres, separated from the main sliver and delivered through a side auxiliary feeding pipe, around the main sliver. Inside the spinning chamber the yarn is formed by the use of a side-pipe twirl around the main bundle, which provides the required strength. Some disadvantages of this method are non-uniformity of fibre mass distribution and inhomogeneous structure of the yarn.

An object of the present invention is to provide an improved method and apparatus for producing yarn.

The present invention uses a pneumatic technique in such a manner that a continuous stream of fibres is provided with a structure which is intact from the point where the fibres have left a drawing apparatus to the place where the yarn has been produced with a real twist, which real twist has been imparted by the use of a non-rotary false twist device.

Imparting a real twist to the yarn increases its strength and creates an opportunity to broaden the linear mass range of produced yarn, permitting the processing of shorter fibres, especially carded medium and short-fibre cotton.

According to one aspect of the invention there is provided a method for the production of yarn comprising:providing a continuous feed of a first bundle of fibres and a continuous feed of a second bundle of fibres from corresponding drafting apparatus, applying an initial twist to one of said bundles in a first twist direction, causing said first and second bundles to converge and applying a fluid vortex induced torsional moment to the joined fibres to induce a final twist in both bundles in a second twist direction which is the reverse of the first twist direction, thereby to produce a yarn.

It has been discovered that introducing two separate bundles of fibres in the manner described above makes it possible to produce yarn, the structure of which is similar to the structure of classic yarn (ring spun).

The twist level of the final twist is preferably equal in magnitude to that of the initial twist.

The initial twist may be imparted alternately to only one at a time of the continuous feeding bundles of fibres, while the other one stays untwisted before the joining of the bundles.

The fluid vortex applied preferably comprises a vortex of air or another gas/gas mixture. The vortex may be formed by introducing compressed air via on or more nozzles into a twisting chamber configured to produced the required vortex.

The first and second bundles of fibres are preferably caused to converge by feeding along respective symmetrical inclines towards an axis of the final twist where said bundles converge.

The bundles are preferably guided to converge by guide means comprising a guide passage for each bundle. The passages are preferably symmetrically arranged on either side of the axis of the final twist.

According to another aspect of the invention the point at which the bundles are converged may be spaced apart form the point at which a torsional moment is applied by the vortex. In this way the reaction to the vortex induced twist may be allowed to induce a back-twist upstream of the vortex induced twisting, which back twist is in the first twisting direction. This back twist alters the structure and properties of the final yarn.

The structure and properties of the yarn may therefore be varied by altering the length of the spacing defined above, and/or the constraint applied to the joined bundles in the spaced region.

The bundles preferably converge and enter into a joining duct downstream of guide passage outlets. The joining duct may space apart the point of convergence and the point of application of torsional moment, thereby permitting a back twist. The joining duct may be sized to have a cross-section of the order of the joined fibre bundles, thereby to constrain said bundles against lateral expansion during back twisting.

The joining duct communicates with a twisting chamber, a longitudinal axis of which may define the axis of the final twist. The twisting chamber is configured to be of suitable shape and dimensions for the generation of the fluid vortex.

The real twist level and the structure of the formed yarn may be altered by (i) varying the relative positions of each guide passage outlet and the configuration of the passages relative to the axis of final twist and (ii) by changing the position and effect of the compressed air nozzles which induce the final twist.

According to the method of the present invention, the portion of the twists which are imparted past the point of applying torsional momentum are reduced by an amount corresponding to the reverse twists imparted to the merged bundles in the common duct before the torsional moment has been applied. The remaining portion of twists, which corresponds to the twist in one of the feeding bundles, is used to create the yarn. Hence the real twist of the yarn is equal to the twist imparted to one of the feeding fibre bundles but with a reverse direction.

The number of real twists in the formed yarn and the structure of the formed yarn can be altered by choosing the ratio of the length of the back twisted stream to the vortex twisted stream. With decreasing length of the back twisted bundles in the joining duct the yarn get increasingly similar to classic ring spun single yarn.

According to yet another aspect of the invention the method can be adapted especially for processing mediumand short-fibre cotton as well as their blends with synthetic fibres. The method of the present invention enables yarn with a differentiated structure to be obtained by altering the length of distance that the joined bundles travel in the joining duct.

According another aspect of the invention there is provided apparatus for the spinning of yarn comprising: a non-rotary spinning chamber provided with first and second guide passages for respective fibre bundles, and means for inducing a twist in one of the bundles, wherein the guide passages converge downstream at a joining duct coaxial with the spinning chamber, which joining duct communicates with a coaxial and downstream twisting chamber adapted to produce a fluid vortex therein.

The guide passages may be symmetrically inclined from a longitudinal axis of the spinning chamber whereby respective outlets of said guide passages converge at the joining duct.

The twisting chamber is preferably provided with one or more compressed air nozzles oriented to produce a vortex of air in the chamber.

The nozzle(s) are preferably positioned at an upstream end of the twisting chamber. The joining duct preferably includes an extension which enters into the twisting chamber thereby forming a baffle around the joined bundles as they enter the twisting chamber. The baffle preferably shields the bundles from the nozzle(s).

The joining passage is preferably cylindrical and the baffle preferably forms an annular lip at a downstream end of the joining passage. An annular recess may be thereby formed between the baffle outer surface and an interior surface of the twisting chamber which carries the nozzle(s).

According to a further aspect of the invention the apparatus for the device consists of a non-rotary spinning chamber provided with a twisting chamber furnished with nozzles which are tangent to its internal wall, a cover with stub pipes supplying compressed air and a hollow container securing air balance.

According to the present invention appropriately situated guide passages and a joining duct enable the production of real twist yarn by the use of a non-rotary false twist apparatus. Moreover, changing an inclination angle of the inlet passages, which allows for a change in the point of joining of the two feeding streams along the axis of the spinning chamber as well as the length of the joining duct, allows the production of yarn in respect of which the structure may be highly differentiated.

Following is a description by way of example only and with reference to the figures of the drawings of methods of putting the present invention into effect.

In the drawings: Figure 1 shows a schematic representation of a first method of producing yarn according to the present invention.

Figure 2 shows a longitudinal section through one embodiment of apparatus according to the present invention.

Figure 3 is a schematic representation of a second method of producing yarn according to the present invention.

Figure 4 is a longitudinal cross section through a second embodiment of apparatus according to the present invention.

Embodiment 1 Figure 1 shows two continuously fed bundles of fibres la and 1b which have been delivered from a drafting apparatus 5. The fibre bundles are each separately introduced into respective inlet pipes of a non-rotary spinning chamber (not shown). An initial twist in a first twist direction is imparted alternately to only one continuous bundle of fed fibres la while the other bundle stays untwisted before the joining of the bundles in the twisting chamber.

The bundles are situated on both sides of the longitudinal axis of the spinning chamber. The bundles are fed symmetrically and inclined from the longitudinal axis as shown in figure 1. Both bundles converge at point A in figure 1 which represents the point of entry into a twisting chamber. An air vortex is thereafter applied to the joined bundles which are thereby subjected to a torsional moment indicated at M. The moment induces a unidirectional final twist in the bundles from the point of applying the torsional moment as far as a line at which seizing of the yarn by delivery rollers (not shown) occurs, indicated generally at 2. The direction of the final twist is opposite in direction to the initial twist of the fed fibre bundle la. The number of real twists applied to the final yarn is equal to that originally applied to one of the feeding bundles. The yarn which is produced has a structure similar to that of classic yarn. It is then led outside the spinning chamber.

Embodiment 2 A second embodiment of the method of the present invention is show schematically in figure 2. The method is as described above in respect of figure 1, with the difference that the torsional moment M is applied downstream of the point of joining A of the fibre bundles 21a and 21b. The reaction to the torsional moment causes an upstream back twist to develop in the region between the point of joining of the fibre bundles A and the point of application of the torsional moment M (indicated at 22). After the air vortex is applied to the fibres the direction of twist reverses, along the length indicated generally at 23.

A device for producing spun yarn according to the present invention is shown in Figure 3. The device comprises a non-rotary spinning chamber 34 with a downstream co-axial twisting chamber 39. The twisting chamber is provided with nozzles 30 that are tangential to an internal cylindrical wall 40 of said twisting chamber. The twisting chamber is further provided with a casing 31 with stub pipes 33 for supplying compressed air to the nozzles 10. The casing 31 is provided with a hollow container 32 for maintaining constant air pressure.

An upstream portion of the non-rotary spinning chamber 34 has two inlet passages 35a and 35b, respective inlets 36a & 36b of which are placed symmetrically of the longitudinal axis L of the spinning chamber 34 and on each side thereof. The passages themselves are symmetrical and inclined from the longitudinal axis L.

The inlet ducts 35 converge into a common joining duct 37 which is situated coaxially with the axis of the spinning chamber 34; a cross-section of the common duct is not smaller than the total summed up cross-section of the inlet passages 35a & 35b.

The outlet of the common duct 37 is inserted into the twisting chamber 39 of the spinning chamber 34 and its edge 42 is placed below the upper edge of the nozzles 30 that inject compressed air. An external diameter of the outlet of the common duct 37 dipped in the twisting chamber 39 is smaller than the internal diameter of this chamber. The twisting chamber 39 is closed at a top end thereof by the wall in the vicinity of which the nozzles 10 have been situated.

A method for the production of yarn, schematically presented in Figure 2 and using the apparatus shown in figure 3 comprises providing two continuously fed bundles of fibres 21a & 21b from a drafting apparatus 25. These bundles are introduced separately into the inlet pipes 35a & 35b of the non-rotary spinning chamber 34. The bundles are each guided along a symmetrical incline from a longitudinal axis L of the spinning chamber. The bundles are then delivered into a common duct 37 disposed along the longitudinal axis the spinning chamber. The fibre bundles converge at this duct.

The converged bundles pass through the common duct and are introduced inside the twisting chamber where they are subjected to a torsional moment M by a vortex air flux.

This causes a right-directional Z-twist to be created from the point of applying the torsional moment M as far as a line of seizing by delivery rollers.

An initial proportion of twists, numbering Z1, is imparted alternately to only one bundle of the fibres 21a before the bundles converge, while the other bundle 21b stays untwisted. Thereafter remaining number Z2 of Z-twists are imparted to the converged bundles in the common duct 37. This section (shown at 2 in figure 2) extends from the point of convergence of the feeding streams A to the point at which a torsional moment M is applied.

On entry into the twisting chamber, and beyond the point of applying a torsional moment M, an S-twist is imparted to the section of merged filaments 3 in the twisting chamber 39. The direction of the twist is opposite to the Z-twist but numbers the same. Because the Z2-twists were made in an opposite direction to the S-twists, the Z2 twists get reduced by the number of S-twists imparted downstream by the air flux.

Hence, the real twist, with a twist level equivalent to the initial Z1-twist level, created in one of the feeding streams before convergence, is imparted to the formed yarn but with having the opposite twist direction. The yarn which is produced is then led outside the spinning chamber. The yarn has a structure similar to that of twisted yarn.

The structure of the yarn and the real twist level imparted to the yarn in the twisting chamber during the constant number of Z-twist created in the section 22 before applying a torsional moment M can be changed by choosing varying the length AM of the merged feeding stream in the common duct. Decreasing the length makes the structure of yarn produced more similar to single classic ring yarn and increases its twist.

Embodiment 3 The device shown in Figure 4 for producing spun yarn is as described above for figure 3, except that each of the inlet passages 35a and 35b is separately joined to the common duct 37 rather than merging to form the duct as in figure 3.

Claims

1. A pneumatic spinning method for the production of yarn comprising: providing a continuous stream of a plurality of bundles of fibres; applying an initial twist to at least one of said bundles in a first in a first direction; thereafter causing said plurality of bundles to converge whereby they are mutually juxtaposed; and applying a fluid vortex induced torsional moment to the juxtaposed fibres to induce a final twist in said bundles in a second twist direction which is the reverse of the first direction.

2. A method as claimed in claim 1 wherein said plurality of bundles consists of a first bundle and a second bundle, and said initial twist is applied to said first bundle.

3. A method as claimed in claim 2 wherein said second bundle is substantially twist free before said bundles are converged.

4. A method as claimed in claim 2 or claim 3 wherein the twist level of the final reverse twist is equal in magnitude to that of the initial twist level applied to the said first bundle.

5. A method as claimed in any preceding claim wherein said bundles are separately introduced into respective inlet passages of a spinning apparatus, which passages converge to cause said bundles to converge.

6. A method as claimed in any preceding claim wherein said bundles are converged symmetrically about a longitudinal axis of drawing of the spun yarn.

7. A method as claimed in any one of the preceding claims wherein the vortex fluid comprises air or another gas or gas mixture.

8. A method as claimed in any preceding claim wherein a point at which the bundles are converged is spaced apart form the point at which a torsional moment is applied by the fluid vortex.

9. A method as claimed in claim 8 wherein the bundles converge at an upstream end of a joining duct and travel downstream in the duct before being emerging in the vortex.

10. A method as claimed in any preceding claim wherein the vortex is applied in a twisting chamber.

11. Apparatus for the spinning of yarn comprising: a non-rotary spinning chamber provided a plurality of guide passages for respective fibre bundles, which guide passages converge downstream and lead to a twisting chamber adapted for the production of a fluid vortex therein and means for inducing a twist in at least one of the bundles upstream of the convergence of guide passages.

12. Apparatus as claimed in claim 11 wherein the guide passages converge into a joining duct which communicates with the twisting chamber.

13. Apparatus as claimed in claim 12 wherein the joining duct is an elongate passage which defines a region wherein a back twist may develop upstream of the twisting chamber.

14. Apparatus as claimed in any of claims 11 to 13 wherein the guide passages are symmetrically inclined from a longitudinal axis of spinning.

15. Apparatus as claimed in any of claims 11 to 14 wherein the twisting chamber is provided with one or more compressed air nozzles oriented to produce a vortex of air in the chamber.

16. Apparatus as claimed in claim 15 wherein the nozzle(s) are positioned at an upstream end of the twisting chamber.

17. Apparatus as claimed in any one of claims 14 to 16 when dependent upon claim 13 wherein the joining duct includes an extension which enters into the twisting chamber thereby forming a baffle around the joined bundles as they enter the twisting chamber.

18. A method or apparatus as claimed in any preceding claim wherein the fibres comprise natural fibres such as cotton.

19. A method or apparatus as claimed in any preceding claim wherein fibres comprise synthetic fibres such as polyester.

20. Apparatus as hereinbefore described and with reference to claim 3 or claim 4 of the drawings.