GB1588964A

GB1588964A - Textile process and device

Info

Publication number: GB1588964A
Application number: GB3365376A
Authority: GB
Original assignee: IWS Nominee Co Ltd
Current assignee: IWS Nominee Co Ltd
Priority date: 1977-08-04
Filing date: 1977-08-04
Publication date: 1981-05-07

Description

(54) TEXTILE PROCESS AND DEVICE (71) We, I.W.S. NOMINEE COMPANY LIMITED, a British Company of Wool House, Carlton Gardens, London, S.W. 1., do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a textile process and device and more particularly relates to a process for feeding slubbings, slivers or rovings to knitting or other textile machines handling fibrous strands and to devices for feeding such strands.

Machine knitting with staple fibres is generally carried out with yarns which have been spun. Attempts to use unspun slivers or slubbings directly in knitting machines have generally not been successful because the forces involved can easily break a sliver or slubbing and result in an unacceptably high breakage rate in the feed. It would nevertheless be an advantage to be able to use slubbings or slivers directly in knitting machines, since one process step, namely spinning, may be omitted with attendant economic advantages.

In our co-pending British Application No.

58551/73 (Serial No. 1 496 654) we describe a process which comprises passing a slubbing, sliver or roving from a restraint through a device for imparting false twist, for example a helical member with an internal diameter such as to impart frictional resistance to the slubbing, sliver or roving, and immediately thereafter passing the slubbing, sliver or roving into a knitting machine.

We have now found that improved and more consistent results can be obtained by using fluid vortex for imparting the false twist to a fibrous strand fed to a textile machine.

According to one aspect of the present invention there is provided a vortex false twist device comprising a first chamber having an inlet for a fibrous strand, a fluid inlet and an exit for the strand, the area for the exit being less than that of the strand inlet, and a second chamber to which the first chamber exit forms an inlet for the strand, the second chamber having a tangentially disposed second fluid inlet and a second exit for the strand, the area of the second exit being greater than that of the first chamber exit.

The preferred form of vortex device comprises two cylindrical chambers joined end to end by an orifice of restricted diameter, one chamber having a radially directed gas inlet passage and the other chamber having a tagentially directed gas inlet passage.

In accordance with a second aspect of the invention there is provided a method of feeding a slubbing, sliver, roving or other relatively untwisted strand of textile fibres to a textile machine in which false twist is imparted to the strand by means of a fluid vortex as it is fed to the machine.

The invention also provides a method of supplying an untwisted strand of staple fibres into a flat bed knitting machine which comprises applying false twist to the strand by means of a tangential fluid vortex while feeding the strand behind the needle bed and, at the end of each feeding movement, stopping the false twist vortex and applying a small tension to the strand to control the selvedge loop formation.

The invention further provides a flat bed knitting machine having as a yarn feeder the false twist device defined above, a source of compressed air or other gas, and cam means for switching the compressed air or gas from the tangential inlet to the other inlet at the end of each feeding movement and back again to the tangential inlet for the start of the next succeeding feeding movement.

The use of such a device not only gives improved false twist but at the same time may control the tension in the strand. The helical device used previously, being in frictional engagement with the strand, often caused the strand to have a tension approaching the strength of the strand which, owing to the multiplying effect of frictional contacts in the further processing of the strand, could cause it to break.

In applying the invention to a knitting machine, the spacing between the false twist device and the needles of the knitting machine should be as small as possible and preferably less than the average length of the fibres in the strand. Conveniently, the device can replace the conventional yarn feed eyelets on the machine.

The vortex system is so designed that mechanical contact is kept to a minimum, so that yarn tension is also minimised. In order to assist further transportation of the strand, the action of the vortex is unidirectional so that the tension in the strand can be reduced by its passage through the vortex unit. This is an advantage in that the strand on the output side is untwisted and is therefore of lower strength than the false-twisted input side.

In the feed to a knitting machine from feed rollers or other tensioning device, the interposition of a false twist device will cause the portion of the feed between the device and the feed rollers to acquire false twist. If the device is positioned as near as possible to the needles, the greatest possible length of the feed will have false twist. If the feed is slubbing, sliver or roving, this false twist will give it increased strength to withstand the tensions involved in knitting.

Fabrics knitted in accordance with the invention are found to be similar in appearance to fabrics knitted from yarn and have adequate strength for normal use. However, as the slubbing in the fabric has no twist, some of the properties of the fabric are different from conventional equivalents.

For example, there is less tendency for the fabric to spiral or cockle, which is advantageous in knitwear.

The process of the invention is not limited to any specific class of staple fibre, but it is particularly advantageous with natural fibres such as mohair, vicuna, alpaca, hair and especially sheep's wool.

When a woollen fabric is knitted by the process of the invention it is desirable to give the fabric a resin treatment to reduce felting shrinkage and this may also increase the pilling resistance.

The device of the invention is applicable to all types of knitting machine, e.g. circular, flat bed or fully-fashioned, and to many other kinds of textile handling machinery, but is particularly advantageous on flat-bed knitting machine.

With flat-bed knitting machines the device carrying the slubbing is reciprocated in supplying the needles. In such cases the gas supply line to the device should be flcxible.

Although the invention has been pri manly described with reference to knitting, it is envisaged that it may also be applied, for example, in supplying weft threads to a weaving loom. Furthermore, it has in the past been difficult to wind tight cones or spools of slubbing or sliver as the strand tends to part under the necessary winding tension. This invention may now be used for winding tighter creels, spools or cones or slubbing or sliver.

The latter aspect of the invention is useful for the production of, for example, filters, which if conventionally wound from slubbing are too loose, and if wound from yarn are not fully efficient, as the medium to be filtered does not pass through the twisted yarn itself but only passes between adjacent yarns.

The invention will be described further, by way of example, with reference to the drawings accompanying the Provisional Specification, in which: Figure 1 is a side elevation, partly in section, of one form of device embodying the invention fitted to a flat-bed knitting machine Figure 2 is a section on the line A-A in Figure 1; Figure 3 is a section on the line B-B in Figure 1; and Figure 4 is a partial plan view of the machine of Figure 1.

As shown in the drawings, the false twist device 10 comprises two cylindrical charnbers 12 and 14 joined by an orifice 16 of diameter less than that of the chambers but greater than that of a wool slubbing 18 passing therethrough. The chamber 12 has a radial air inlet 20 (see Figure 2) connected by a tube 22 and an air switch or valve 24 to a compressed air supply (not shown). The chamber 14 has a tangential air inlet 26 connected by a tube 28 to the same switch 24 and air supply. The slubbing 18 passes through the device 10 and a yarn guide 30 to be fed to the needles 32 of the flat-bed knitting machine.

The air tubes 22 and 28 are flexible and the whole assembly of the false twist device 10 and the yarn guide 30 can be moved along the needle-bed 40 (see Figure 4) to lay-in the slubbing 18 behind the needles in the normal manner for a flat-bed machine.

The air switch 24 is operated by a pair of cams 34, 36 each of which is adjustably fixed to the machine frame 38. The cams are mounted in positions which correspond to the selvedges of the fabric being knitted.

During the movement of the device/yarn guide assembly along the needle bed 40 the air switch 24 feeds compressed air along tube 28 to the chamber 14 thus producing an air vortex in the chamber, thereby causing false twist to be inserted in the slubbing 18 to give it strength. Owing to the restricted orifice 16, the bulk of the air from the inlet 26 escapes from the bottom of the chamber 14 thus urging the slubbing 18 towards the needle bed 40, where it is caught by the needles 32 and knitted into fabric.

At either end of the knitting movement the switch 24 engages one of the cams 34 or 36 and switches the air supply along the tube 22 into the chamber 12. As the inlet 20 is radial no twist is inserted by this air flow and, owing to the restricted orifice 16, most of the air escapes at the top of the chamber 12 thus urging the slubbing 18 backwards and applying tension to that portion of the slubbing between the needles 32 and the device 10. This small tension is necesary at the end of each knitting movement so that the selvedge of the fabric is properly formed and does not have loose or uneven loops. On recommencement of knitting (now in the opposite direction) the cam disengages, air returns to the tube 28 and the inlet 26, and false twist is applied as before.

In this manner an entirely satisfactory fabric can be knitted from untwisted strands thus cutting out the spinning operation and reducing the cost of the end product.

WHAT WE CLAIM IS: 1. A method of feeding a slubbing, sliver, roving or other relatively untwisted strand of textile fibres to a textile machine in which false twist is imparted to the strand by means of a fluid vortex as it is fed to the machine.

2. A method of supplying an untwisted strand of staple fibres to a flat bed knitting machine which comprises applying false twist to the strand by means of a tangential fluid vortex while feeding the strand behind the needle bed and, at the end of each feeding movement, stopping the false twist vortex and applying a small tension to the strand to control the selvedge loop formation.

3. A method according to claim 2 wherein the distance between the false twist device and the needles of the machine is less than the average length of the fibres in the strand.

4. A method according to claim 1, 2 or 3 wherein the fibres of the strand are wool.

5. A method of feeding an untwisted strand of staple fibres to a knitting machine substantially as described with reference to the drawings accompanying the Provisional Specification.

6. A false twist device adapted to impart false twist to a fibrous strand in the method of any claims 1 to 4 comprising a first chamber having an inlet for a fibrous strand, a fluid inlet and an exit for the strand, the area for the exit being less than that of the strand inlet, and a second chamber to which the first chamber exit forms an inlet for the strand, the second chamber having a tangentially disposed second fluid inlet and a second exit for the strand, the area of the second exit being greater than that of the first chamber exit.

7. A device according to claim 6, wherein the two chambers are cylindrical and coaxial and communicate through an orifice of restricted diameter, the first chamber having a radially directed gas inlet and the second chamber a tangentially directed gas inlet.

8. A false twist device substantially as described with reference to Figs. 1 to 3 of the drawings accompanying the Provisional Specification.

9. A flat bed knitting machine including a yarn feeder comprising a false twist device according to any of claims 6 to 8, a source of compressed air or other gas, and cam means for switching the compressed air or gas from the tangential inlet to the other inlet at the end of each feeding movement and back again to the tangential inlet for the start of the next succeeding feeding movement.

10. A knitting machine including a fluid vortex false twist device substantially as described with reference to the drawings accompanying the Provisional Specification.

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Claims

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18 towards the needle bed 40, where it is caught by the needles 32 and knitted into fabric.

At either end of the knitting movement the switch 24 engages one of the cams 34 or 36 and switches the air supply along the tube 22 into the chamber 12. As the inlet 20 is radial no twist is inserted by this air flow and, owing to the restricted orifice 16, most of the air escapes at the top of the chamber 12 thus urging the slubbing 18 backwards and applying tension to that portion of the slubbing between the needles 32 and the device 10. This small tension is necesary at the end of each knitting movement so that the selvedge of the fabric is properly formed and does not have loose or uneven loops. On recommencement of knitting (now in the opposite direction) the cam disengages, air returns to the tube 28 and the inlet 26, and false twist is applied as before.

In this manner an entirely satisfactory fabric can be knitted from untwisted strands thus cutting out the spinning operation and reducing the cost of the end product.

WHAT WE CLAIM IS: 1. A method of feeding a slubbing, sliver, roving or other relatively untwisted strand of textile fibres to a textile machine in which false twist is imparted to the strand by means of a fluid vortex as it is fed to the machine.
2. A method of supplying an untwisted strand of staple fibres to a flat bed knitting machine which comprises applying false twist to the strand by means of a tangential fluid vortex while feeding the strand behind the needle bed and, at the end of each feeding movement, stopping the false twist vortex and applying a small tension to the strand to control the selvedge loop formation.
3. A method according to claim 2 wherein the distance between the false twist device and the needles of the machine is less than the average length of the fibres in the strand.
4. A method according to claim 1, 2 or 3 wherein the fibres of the strand are wool.
5. A method of feeding an untwisted strand of staple fibres to a knitting machine substantially as described with reference to the drawings accompanying the Provisional Specification.
6. A false twist device adapted to impart false twist to a fibrous strand in the method of any claims 1 to 4 comprising a first chamber having an inlet for a fibrous strand, a fluid inlet and an exit for the strand, the area for the exit being less than that of the strand inlet, and a second chamber to which the first chamber exit forms an inlet for the strand, the second chamber having a tangentially disposed second fluid inlet and a second exit for the strand, the area of the second exit being greater than that of the first chamber exit.
7. A device according to claim 6, wherein the two chambers are cylindrical and coaxial and communicate through an orifice of restricted diameter, the first chamber having a radially directed gas inlet and the second chamber a tangentially directed gas inlet.
8. A false twist device substantially as described with reference to Figs. 1 to 3 of the drawings accompanying the Provisional Specification.
9. A flat bed knitting machine including a yarn feeder comprising a false twist device according to any of claims 6 to 8, a source of compressed air or other gas, and cam means for switching the compressed air or gas from the tangential inlet to the other inlet at the end of each feeding movement and back again to the tangential inlet for the start of the next succeeding feeding movement.
10. A knitting machine including a fluid vortex false twist device substantially as described with reference to the drawings accompanying the Provisional Specification.