US2905976A

US2905976A - Drafting of textile fibres

Info

Publication number: US2905976A
Application number: US584823A
Authority: US
Inventors: John A Matthew; John L Spencer-Smith
Original assignee: LINEN INDUSTRY RES ASS OF
Current assignee: LINEN INDUSTRY RES ASS OF; LINEN INDUSTRY RESEARCH ASSOCIATION OF RESEARCH INSTITUTE
Priority date: 1955-04-01
Filing date: 1956-05-14
Publication date: 1959-09-29
Anticipated expiration: 1976-09-29

Description

a Sept. 29, 1959 Filed May 14, 1956 J. A. MATTHEW ETAL DRAFTING OF TEXTILE FIBRES FIG. 1

7 Sheets-Sheet 1= Inventor:

Attorneys Sept. 29, 1959 J. A. MATTHEW ET AL 2,905,976

- DRAFTING OF TEXTILE FIBRES Filed May 14. 1956 '7 Sheets-Sheet 2 Inventor: m L'MIEIZ...

Attorneys Sept. 29, 1959 J. A. MATTHEW ETAL 2,905,976

DRAFTING OF TEXTILE FIBRES Tsheets-sheet 3 Filed May 14, 1956 p 1959 J. A. MATTHEW ETAL 2,905,976

DRAFTING OF TEXTILE FIBRES 7 Sheets-Sheet 4 Sept. 29, 1959 J. A. MATTHEW ETAL DRAFTING OF TEXTILE FIBRES Filed May 14, 1956 7 Sheets-Sheet 5 Sept. 29, 1959 Filed May 14, 1956 J. A. MATTHEW ET AL DRAFTING OF TEXTILE FIBRES '7 Sheets-Sheet 6 CQD rwentors Attorney Sept. 29, 1959 J. A. MATTHEW ET AL ,9

DRAFTI-NG 0F TEXTILE FIBRES Filed May 14, 1956 7 Sheets-Sheet 7 120 F/G. I2 117 Attorney;

United States a Patent DRAFTING OF TEXTILE FIBRES John A. Matthew and John L. Spencer-Smith, Lambeg, Northern Ireland, assignors to Linen Industry Research Association of The Research Institute, Lamheg, Northern Ireland, a body corporate of Great Britain Application May 14, 1956, Serial No. 584,823

'6 Claims. (Cl. 19-70) The invention relates to the process of drafting or attenuating between pairs of rollers, on spinning, roving or drawing frames, twisted or untwisted slivers composed of natural staple fibres such as flax, cotton, wool, or jute, or of man-made staple fibres such as rayon, nylon, Terylene or the like, and to apparatus to control the irregularity in the drafted sliver, characterised by the production of automatic changes in the drafting conditions that vary according to measurements of the variations, at any instant, in the number of fibres which are gripped by the drafting rollers, or are present at a suitable point either in the drafted or undrafted sliver or at a suitable point in the reach between the feed and drafting rollers or to measurements of the variations in regularity required in the drafted sliver. The drafting conditions may be varied by automatic changes in the action of so called fibre control devices in the reach, in the efiective length of the reach by movement of the position of one of the pairs of rollers or in the length of sliver in a fixed reach, or by changes of the mechanical draft.

In known fibre control devices between the pairs of rollers consisting of guide plates, bars or the like, or of single pairs of rollers which are rotated, or of endless belts or aprons which are positively driven, or a combination of some or all of these, the said apparatus remains unchanged during drafting.

It is well known that these devices have optimum positions or adjustments and effect an improvement in the regularity of the drafted sliver by reducing the uncontrolled movement of fibres that are not gripped by the drafting rollers, but they have little effect in reducing irregularities that are present in the undrafted sliver, with the result that the presence of a thick place or an excessive number of fibre ends per unit length in the undrafted sliver necessarily produces a thick place in the drafted sliver, and similarly thin places in the undrafted sliver cause thin places in the drafted sliver.

The object of the present invention is to provide apparatus to be used either alone or in conjunction with any of the known fibre control devices, for controlling the drafting conditions automatically either immediately or after a suitable time delay and according to the signals of one or more detector heads which measure the numbers of fibres which are gripped or are delivered by the drafting rollers, or which are present in the sliver at a suitable point either in the reach between the feed and drafting rollers or behind the drafting rollers, or which measure the tension of the sliver in the reach between the said rollers, or some suitable combinations of some of these measurements, whereby the number of fibres which are about to be gripped by the drafting rollers is reduced or increased respectively either immediately or at a suitable interval of time after an increase or decrease in the number of fibres or in the sliver tension, or in both, has been detected by the said detector head or heads.

The principle of the invention may be applied in several different ways as follows:

(1) To control or reduce the short period irregularly of the drafted sliver by varying automatically the position of either the control devices introduced between the feed and drafting rollers of the frame, and/or the position or instantaneous speed of the feed rollers or both, according to either the variations in the thickness, weight per unit length or the number of fibres in a cross section of the sliver at a suitable point either in the reach between the said rollers, or in the drafted sliver leaving the drafting rollers, or the variations in the tension of the sliver at a suitable point in the reach between the said rollers, or according to some combination of both, so that the number of fibres which are presented to the drafting rollers is reduced or increased, respectively, either at a suitable interval of time after an increase of decreasein the number of fibres in the sliver, either at a suitable point in the reach or at a suitable point behind the feed rollers, or immediately there is an increase or decrease in the tension of the sliver in the reach between the drafting and feed rollers, or immediately there is an increase in the value of a suitable index which combines the effect of the tension of the sliver in the reach and the number of fibres at a suitable point in the reach, so that the drafted sliver is made more uniform than would otherwise be the case. The magnitude of the irregularity in the drafted sliver may be controlled by varying the amount or direction of the movement of the control device or of the feed rollers or of both produced by a given change in the thickness or tension of the sliver between the feed and drafting rollers, so that yarn of practically any degree of levelness may be produced.

(2) To control or reduce the short period irregularity of the drafted sliver by varying automatically either immediately or after a suitable delay, the action of control devices, such as positively driven pairs of rollers, endless belts or aprons, introduced between the feed and drafting rollers of the frame according to either the measured variations in the thickness, weight per unit length of number of fibres in a cross section of the sliver at a suitable point in the reach between the said rollers, or to the measured variations in the tension of the sliver at a suitable point in the reach between the said rollers, or to some combination of the said measurements, whereby when the said measurement indicates that fewer fibres are about to be gripped by the drafting rollers, the action of the said control device or devices is altered to increase thenumber of fibres to be drawn out with those fibres already gripped by the drafting rollers. Similarly when the said measurement indicates that more fibres are being or about to be gripped by the drafting rollers the action of the said control device is altered to increase the control of those fibres which are not gripped by either the drafting or the feed rollers and thereby to allow fewer floating fibres to be drawn out with those already gripped by the drafting rollers. In this Way the magnitudes of potential thin places in the drafted sliver are increased and the magnitudes of potential thick places in the drafted sliver are proportionately reduced and the drafted sliver is thereby made more level than it would otherwise be. The magnitude of the irregularity in the drafted sliver can be controlled by varying the amount or direction of the change of action of the said control device for a given change in the thickness or tension of the sliver, so that yarn of practically any degree of levelness can be produced.

(3) To introduce prescribed variations into the thickness such as slubs or thick places at predetermined places along a yarn, whereby the fibre control devices introduced between the feed and drafting rollers are controlled by the thickness or tension of the sliver being drafted as in the first application for most of the time but whose action or position is suddenly varied by impulses at predetermined times to introduce thicks into the drafted sliver or yarn. The impulses may be derived from measurements made by a suitable gauging head of the variations in thickness along the length of a standard yarn which it is desired to match or by any other suitable means. In the former case the operation of the control devices may be controlled partly by the variations in thickness or tension of the sliver as in the first application and partly by the variations in thickness along a suitable standard yarn whereby the irregularities in the drafted sliver or yarn may be made substantially the same as those in the standard yarn.

(4) To control or reduce the long period irregularity of the drafted sliver by providing new and improved methods for reducing the long period variations in the drafted sliver by varying the draft between the drafting and feed rollers, by varying either the speed of the feed roller, or the speed of delivery of the sliver by the feed rollers, after a suitable time delay, according either to the thickness, or weight per unit length or number of fibres in a cross section or to the difference thereof from a running average during a predetermined previous interval of time, of the sliver at a suitable point either between the feed rollers and the drafting rollers or behind the feed rollers, so that when the sliver being fed into the feed rollers becomes heavy or light respectively, the draft is automatically increased or decreased in order to maintain the drafted sliver at a substantially constant weight per unit length.

(5) To stop delivery of the sliver by the feed rollers when the said sliver contains a gross irregularity or fault such as a length which is excessively thick or thin respectively and the variation in thickness is too great to be eliminated by the automatic variation of the drafting control device, as described under the first, second and fourth applications of the invention, or by the automatic variation of the draft whereby the presence of too many or too few fibres at a suitable point either in the reach between the drafting and feed rollers, or too great or too small a tension on the sliver in the said reach is made to operate a stop motion to prevent delivery of the faulty length of sliver by the feed rollers.

According to the invention the apparatus for the first, second and third applications of the invention, namely for reducing the short period irregularties in the drafted sliver, and for introducing prescribed variations in the thickness of the drafted sliver or yarn, comprises a detector device, a transducer or servo mechanism for producing a movement, pressure or rate of movement, which is substantially proportional to the change of thickness or of tension of the sliver or to the change in some combination thereof, as detected by the feeler device with or without a time delay mechanism which delays the response of the transducer for a suitable predetermined in terval of time, and a control device, actuated by the said transducer, whereby the supply of fibres to the drafting rollers, as determined by the mechanical draft between the rollers and the drafting conditions, is varied either wholly in proportion to signals from the detector device to compensate for the irregularties in the undrafted sliver, or partly in proportion to signals from the detector head and partly by an independent motion to introduce a predetermined system of irregularities of known magnitude and sequence.

According to the invention the apparatus for the fourth application for reducing the long period variations in the yarn by automatic variation of the draft according to the thickness of the sliver being fed into feed rollers, comprises a detector unit for measuring the thickness of the undrafted sliver, a transducer device for producing a movement which is substantially proportional to the thickness of the sliver which has occurred during a predetermined interval or to the difference between the thickness of the sliver at the point at which it is gauged and a running average thereof, a time delay device for delaying the eifect of a change in sliver thickness for a suitable predetermined interval of time, and apparatus '4 for varying the speed or rate of delivery of the sliver from the back rollers.

The apparatus according to the invention is more particularly described with reference to the following figures:

Fig. 1 shows the general layout of the apparatus according to the first application of the invention, in which the position of a guide member is varied in accordance with the measurements of the tension of the sliver or rove during drafting or the weight per unit length of the sliver or rove during or after drafting.

Fig. 2 shows a preferred form of the apparatus shown diagrammatically in Fig. 1.

Figs. 3(a) and (b) show pneumatic gauging units for producing a back pressure which varies substantially with the tension of the rove or sliver being drafted or with the weight per unit length of the yarn after drafting.

Fig. 3(c) shows a pneumatic gauging unit for providing a pneumatic pressure which varies substantially as the weight of the sliver or rove being drafted.

Fig. 3(d) shows a pneumatic gauging unit for producing a pneumatic pressure which is proportional to the tension of the rove or sliver.

Fig. 4 shows a mechanical apparatus for varying the position of a guide member in accordance with the tension of the rove or sliver being drafted.

Fig. 5 shows a pneumatic transducer for varying the position and the instantaneous velocity of the feed rollers in accordance with a pneumatic pressure.

Fig. 6 shows a pneumatic system for damping and delaying the response of the pneumatic transducer unit to a change in pressure.

Fig. 7 shows a pneumatic transducer for varying the instantaneous velocity of the feed rollers.

Fig. 8 shows the general arrangement of the apparatus according to the first application of the invention for varying the position and/or the instantaneous velocity of the feed rollers in accordance with variations in the tension of the sliver or rove during drafting or the weight per unit length of the sliver or rove during drafting.

Fig. 9 shows the general arrangement of the pneumatic apparatus for varying the pressure between a pair of carrier rollers according to the tension of the sliver or rove being drafted or to the weight per unit length of the sliver or rove during drafting.

Fig. 10 shows a mechanical arrangement for varying the pressure between a pair of carrier rollers in accordance with the tension of the rove or sliver being drafted.

Fig. 11 shows apparatus according to the third application of the invention to introduce slubs or thick places simultaneously into a plurality of yarns.

Fig. 12 shows apparatus according to the fourth application of the invention to reduce the long period varia tions in the drafted sliver or yarn.

Fig. 13 shows a self threading device for gauging the weight per unit length of the sliver pneumatically.

Fig. 14 showsapparatus according to the fifth application of the invention to stop delively of the sliver or rove to or by the feed rollers when the signal from the gauging unit indicates an excessive variation in the thickness of the sliver or rove being drafted.

In'Fig. l, the sliver or rove 1 to be drafted passes through the pair of positively driven

feed rollers

2, 2, over or through the various control and gauging members, 4, 5, 7 and 8 to the pair of positively driven

drafting rollers

3, 3, from which it emerges as drafted sliver of yarn 9.

The sliver 1 emerging from the

feed rollers

2, 2, passes over or through a guide or control member 4-, over the guide member 5, which is attached to and moved by the transducer 6 in a direction which is substantially perpendicular to the direction of travel of the yarn and in accordance with the signal from the gauging unit'7 either immediately or after a suitabledelay, and thence to a second guide-or control member 8, over or through the gauging ,unit 7, to the

drafting rollers

3,3. The

gauging unit 7 may be alternatively positioned between the

feed rollers

2, 2, and the guide or control member 4 or on the drafted sliver or yam 9, after it emerges from the

drafting rollers

3, 3. Alternatively, .the gauging unit 7 may be incorporated in any of the guide or

control members

4, 5 and 8. The guide or control members 4 and 8 may be single or a plurality of stationary rods or guides or they may consist of a single or a plurality of positively driven rollers or of pairs of plain or flanged rollers of which one is positively driven whilst the other rests on it or they may consist of single or pairs of positively driven belts or aprons. In the case of drafting slivers of fibers such as flax or uncrimped rayon staple, stationary rods or guides may be used but in the case of drafting crimped fibers such as wool, cotton or crimped staple man-made fibers, positively driven rollers or pairs of belts are preferred. Alternatively, either or both of the guide and control members 4 and 8 may be dispensed with or the gauging unit 7 may be incorporated in the movable guide 5. When the gauging unit 7 measures the tension of the sliver or rove it may be placed at any point on the line of the sliver between the feed and the drafting rollers.

In Fig. 2 the rove 1 from the

feed rollers

2, 2, passes over the grooved guide 10 which is attached to an arm 11, Which is freely pivoted at 12 and is attached to the end of a pneumatic bellows 13 which is normally partly compressed by the spring 14. The rove 1 then passes over the gauging unit 15 which consists of a tube having a V groove containing a small orifice 16 on which the rove bears, and thence to the drafting

rollers

3, 3. The gauging unit 15 is mounted on a tube- 17 which is connected through a restrictor 18 to the pneumatic bellows 13 and also through a second restrictor 19 in a tube 20 to a. source of compressed air at constant pressure.

The gauging unit 15 which is shown in greater detail in Fig. 3(a) when arranged in conjunction with the restrictor v19 and the source of compressed air 20 develops a back pressure which varies substantially in proportion to the tension of the rove 1 and which is communicated through the restrictor 18 to the bellows 13 which thereby expands and contracts in accordance with the fluctuations in tension of the rove. When roves of a staple fibre in which the lengths of the fibres do not vary excessively, are drafted on this arrangement the rove tension and the back pressure developed by the gauging unit 15 varies substantially in proportion to the number of fibres which are gripped and being drafted by the drafting

rollers

3, 3.

The operation of the apparatus illustrated in Fig. 2 is as follows:

When the number of fibres being drafted by the

rollers

3, 3, increases, the tension of the rove is increased and causes the pneumatic pressure behind the gauging unit 15 to increase and in consequence the pressure in the bellows 13 begins to increase and the said bellows expands and moves the guide 10 perpendicularly to the line of the rove and increases the effective length of the path of the rove between the

feed rollers

2, 2, and the drafting

rollers

3, 3, thereby momentarily reducing the supply of fibres to the drafting rollers and consequently reducing the magnitude of the thick place which would have ap peared in the yarn. When the number of fibres being drafted decreases, the rove tension and therefore the back pressure developed by the gauging unit 15, decreases and the bellows 13 begins to contract, thereb} momentarily increasing the supply of fibres to the draft ing rollers to compensate for the thin place which would otherwise have occurred in the yarn.

The gauging unit 15 may be placed in other positions or used in conjunction with other guide and control members as described with respect to Fig. 1. When the gauging unit, consisting of a small orifice 16 in a V groove as shown in Fig. 3(a), is placed below the drafting rollers on a spinning frame, the back pressure developed varies 6 substantially in proportion to the thickness of the twisted yarn over the gauging jet.

Fig. 3(b) shows an alternative form of shape for the groove, in the pneumatic gauging unit for gauging the tension ofthe rove.

The pneumatic gauging unit shown in Fig. 3(a) contains an orifice 16 in the form of a narrow slot cut perpendicularly to the path of the rove and produces a pneumatic back pressure which varies substantially as the thickness of rove lying over the slot and this form of igauging unit is preferred for drafting roves of flax fibre and other materials in which lengths of the fibres vary greatly.

The amount of compensation and the irregularity of the spun yarn can be controlled by varying the pneumatic pressure supplied to the apparatus, by altering the size of the

restrictors

18 and 19, or by altering the angle of bearing of the rove over the guide 10. The restrictor -18 must be sufficiently small to prevent the bellows 13 from contracting so fast that the rove 1 goes slack in the reach.

The rove 1 as shown in Fig. 3d passes behind fixed

rods

21 and 22, and in front of a bar 23, which is attached to a hinged arm 24 freely pivoted at 25 and connected through a light compression spring 26 to a pneumatic bellows .27 which may operate against a spring. The hinged arm 24 carries a light vane 28 which moves between two

opposed orifices

29 and 30, the orifice 29 being connected to a supply of compressed air whilst the orifice 30 is connected through a restrictor 31 to the bellows 27 and through a tube 32 which leads to a pneumatic transducer such as 6 in Fig. l or to the restrictor 18 and bellows 13 in Fig. 2. The operation of this pneumatic gauging unit is as follows: When a tension is applied to the rove 1, the rod 23 and the hinged arm 24 and vane 28 are displaced backwards thereby allowing compressedair to flow from the orifice 29 to the orifice 3t}, and thence through the restrictor '31 to the pneumatic bellows 27 which expands and compresses the spring 26 until it forces the arm 24 outwards and the vane 28 partially cuts off the flow of air from the orifice 29 to the orifice 30. The pressure of the air in the pneumatic bellows 27 and the tube 32 is maintained at a value which maintains the vane 28 in this position, consequently the rod 23 is maintained in a fixed position and the pneumatic pressure varies in proportion to the rove tension. The sensitivity of the tension gauging unit i.e. the increase in pressure for a given increase in tension can be altered either by altering the strength of the springs 26 or the spring against which the bellows operate, or changing the position of the

orifices

29 and 30.

In the mechanical tension gauging unit and transducer shown diagrammatically in Fig. 4 a rod 33 sliding between free bearings or guides 34 and 35 carries at one end a freely sliding tube 36 which is connected to the rod 33 by a light compression spring 37 and carries a guide member 38 on which the rove :1 bears and which is fitted with two

lugs

39, 40. A cord 41 attached to the lug 39 passes over a known type of torque amplifier such as a drum 42 which is rotated positively in the direction indicated, and thence to a lug 43 attached to the rod 33. A similar cord 44 attached to the lug 40 passes over a second known type of torque amplifier such as a drum 45 which is rotated positively in the direction indicated, and thence to the lug 46 attached to the rod 33.

The operation of the apparatus is as follows: The lengths of the

cords

41 and 44 are adjusted initially so that when the rove 1 is under the average drafting tension, the rod 33 is approximately at the mid point of its possible travel. When the tension of the rove 1, bearing on the guide member 38 increases the spring 37 is compressed slightly and the tube 36, slides a small distance along the rod 33, thereby producing in the cord 41 tension which is amplified by the rotating drum 42 to provide a sufiicient force to move the rod 33, and

the guide member 38 outwards. When the tension on the rove decreases the spring 37 expands slightly thereby releasing the tension from the cord 41 and producing in the cord 44, a tension which is amplified by the drum 4 5 to move the rod 33 and the guide member 38 inwards.

In the pneumatic transducer shown in Fig. 5 the position and velocity of the feed rollers is varied according to the pneumatic pressure developed by a pneumatic gauging unit for the tension or weight per unit length of the rove as described with reference to Fig. 3(a) and The rove 1 being drafted is fed through the

feed rollers

47, 48 which are mounted on an arm 49 which is carried on a free bearing 50 on a positively driven shaft 51, carrying a gear wheel 52, which drives a similar gear wheel 53, attached to the feed roller 48. The end of the arm 49 is supported by a plunger 54, attached to a pneumatic bellows S5, enclosed by a casing 56 and operating against a compression spring 57. The arm 49 also carries a pair of

opposed orifices

58 and 59 the orifice 58 being connected to a supply of compressed through the valve 101 and the orifice 59 being connected to the casing 56 of the bellows 55. The supply of air from the orifice 58 to the orifice 59 is interrupted by a vane 60 which is attached to a hinged arm 61 pivoted at 62 and attached to a bellows 63 and a light compression spring 64. The bellows 63 is connected through the valve 100 to a pneumatic gauging unit which may be as indicated in any of Figs. 3(a), (b), (c) or (d), and situated as described with reference to Fig. l for providing a pneumatic pressure of air which is substantially proportional either to the weight per unit length or to the tension of the rove, so that the lever arm 61 and the vane 60 move up and down according to the pressure developed by the said gauging unit. The pressure of the air between the bellows 55 and the easing 56 increases to the value which maintains the arm 49 in a position in which the flow of air between the

orifices

58 and 59 is partially obstructed by the vane 60 so that the arm 49 moves the

feed rollers

47, 48 up and down according to the extension of the bellows 63, i.e. to the tension or weight per unit length of the rove as measured by the gauging unit. As the arm 49 moves upwards as a result of an increase in either the weight per unit length or the tension of the rove as detected by the gauging unit, the

feed rollers

47, 48 during the movement rotate more slowly, whereas when the arm 49 moves downwards the

feed rollers

47, 48 rotate more quickly, so that the variation in the rate at which fibres are fed to the drafting rollers is increased or decreased partly by the movement of the arm 49 carrying the

feed rollers

47, 48 varying the distance of these rollers from the drafting rollers and partly by the change in speed of the said

feed rollers

47 and 48 produced during this movement.

The rove 1, leaving the

feed rollers

47 and 48 may pass through or over any known arrangement for controlling the fibres during drafting, such as any arrangement of fixed guides or rods, single or pairs of positively driven rollers, belts or aprons or the like before passing through the drafting rollers, and the pneumatic gauging unit may be placed in any of the positions described with reference to Fig. l.

The operation of the apparatus described with reference to Fig. 5 is as follows: When the tension of the rove or its weight per unit length increases, i.e. there is an increase in the number of fibres gripped or about to be gripped by the drafting rollers the pneumatic gauging unit provides an increased pneumatic pressure which is fed either directly or through a series of capillary tubes to the bellows 63 which commences to expand raising the vane 60 above the line of the

opposed orifices

58 and 59. This allows air to pass from the orifice 58 to the orifice 59 and thence to the bellows 57 which is compressed to raise the lever arm 49 to follow the movement of the bellows 63. The upwards movement of the arm 49, increases the leng h of the reach, i.e. the distance between the feed rollers and the drafting rollers and decreases the speed of the

feed rollers

47, 48 momen tarily thereby reducing the supply of fibres to the nip of the drafting rollers thus compensating for the increased number of fibres detected by the gauging jet. Similarly when the gauging unit indicates a reduction in the Iove tension or weight per unit length of the rove, i.e.' a reduction in the number of fibres which are or are about to be gripped by the drafting rollers, the lever arm 49 moves downwards to follow the movement of the bellows 63 and the consequent reduction in the reach and the simultaneously momentary acceleration of the feed rollers increases the supply of fibres to the drafting rollers thereby compensating for the reduction which was detected by the gauging unit.

The amount of compensation and therefore the improvement in the regularity of the drafted slivers or yarn can be adjusted by varying the distances of the

opposed orifices

58 and 59 together with the distance of the bellows unit 6%, 61, 62, 63 and 64, from the bearing 50 on the positively driven shaft or by varying the sensitivity of the gauging unit.

Yarns which are more irregular than normal can be spun by reversing the direction of movement of the

bellows unit

60, 61, 62, 63 and 64, so that the supply of fibres to the drafting rollers is increased when the gauging unit detects an increase in the number of fibres being or about to be drafted and the supply of fibres to the drafting rollers is reduced when the gauging unit detects a decrease in the number of fibres being or about to be drafted. The character of the irregularity and more especially the average distance between successive thick or thin places in the yarn can be varied by introducing suitable damping and delays to the increase of pres sure in the bellows 63 as shown by the arrangement in Fig. 6 in which the pneumatic pressure developed by a suitable pneumatic gauging unit 65 which may be of the types described with reference to Figs. 3(a) (b) (c) ((1), passes through a restrictor 66 to a closed vessel 67 and thence through a second restrictor 68 to a second closed vessel 69 and finally through a third restrictor 70 to the bellows 63. The number of closed vessels and restrictors in the pressure line may be varied to produce different amounts of damping and different time delays.

In the arrangement shown in Fig. 7 the signal from the gauging unit is made to produce momentary fluctuations in the speed of the

rollers

71, 72, of which 72 is driven from a positively driven shaft 73 through a differential gear consisting of

bevel wheels

74, 75, 76, mounted in a frame 77 which is capable of being rotated about the axis of the shaft 73 by a pneumatic transducer unit 78 acting on a stud 79 in a slot 80 attached to the frame 77 and operated by a pneumatic signal from a pneumatic gauging unit which may be of any of the types described in Figs. 3(a), 3(b), 3(0) or 3(d).

The operation of the apparatus is as follows: When an increased pneumatic pressure is transmitted to the transducer 78 from the gauging unit indicating an increase in the number of fibres which are about to be, or are being drafted by the drafting rollers, the transducer 78 moves the stud 79 to rotate the frame 77 in a direction which momentarily reduces the speed of the

bevel gear wheels

75 and 76 which thereby momentarily reduces the speed of the

feed rollers

71, 72 and so reduces the supply of fibres to the nip of the drafting rollers thereby compensating for the increase in the number of fibres detected by the gauging unit. Similarly when the gauging unit detects a decrease in the number of fibres which are about to be, being or which have just been drafted, the transducer 78 moves the stud 79 to rotate the frame 77 in a direction which momentarily increases the speed of the

gears

75 and 76 thereby momentarily increasing the speed of the

feed rollers

71 and 72, so increasing the supply of fibresrto the drafting rollers to compensate for 9 the decrease in the number of fibres detected by the gauging unit.

In the general arrangement shown in Fig. 8 of the apparatus using the transducers described with respect to Figs. or 7 the rove 1 is fed through the

feed rollers

81, 82, whose position and/or speed is varied by the said transducer 83. The rove then passes through one or more fibre control units 84 which may consist of known types of guide bars, single or pairs of rollers, belts, aprons or the like, through a gauging unit 85 of any of the types described with reference to Figs. 3(a), (b), (c) or (d) or 13 for gauging either the thickness of the rove or the tension or a combined index thereof, and thence to the drafting rollers 86. Alternatively the tension gauging unit may be positioned adjacent the fibers extending between

feed rollers

81 and 82 and the fiber control units 84 for measuring the thickness or weight per unit length. The gauging also may be positioned adjacent the fibers after they are passed through the drafting rollers 86. The fibre control units 84, may be dispensed with or the gauging unit may be incorporated into a fixed guide of the fibre control unit without departing from the scope of the invention.

In the apparatus for performing the second application of the invention shown diagrammatically in Fig. 9, the rove 1 passes through the

feed rollers

89, 90 through one or more pairs of rollers 91 which are lightly pressed together and driven at a somewhat higher surface speed than the feed rollers to a roller 92 driven at a somewhat higher surface speed than the feed rollers and against which a second roller 93 bears. The roller 93 is mounted on an arm 94 which is pivoted at 95 and against which a pneumatic transducer 96 bears. The arm 94 will thus move in accordance with the signal from the pneumatic gauging unit 97 through which the rove passes before passing through the drafting rollers 3.3, and the pressure of the roller 93 against the roller 92 will be varied correspondingly. The pneumatic gauging unit 97 may measure either the tension or the weight per unit length of the rove or some combination thereof.

When a pneumatic gauging unit for measuring the weight per unit length of the rove is used it may be placed in a position which is adjacent the fibers below the drafting rollers 33. The arm 94 may be fitted with a spring or a light counter poise weight which is adjusted to give a light pressure on the rollers under normal drafting conditions.

The

rollers

92 and 93 may be plain or one may consist of a narrow roller fitting into a groove in the other rollers with a suitable conductor to lead the sliver or rove into the groove either or both rollers may be replaced by a positively driven belt or apron, without departing from the scope of the invention. Similarly the pairs of rollers 91 may be dispensed with or replaced by any known fibre control device or devices without departing from the scope of the invention.

The operation of the apparatus is as follows: When the number of fibres which are being or are about to be gripped by the drafting rollers increases, the pneumatic gauging unit 97 produces an increased pressure which is transmitted through the transducer 96 to increase the pressure between the

rollers

92 and 93, thereby improving the fibre control to reduce the number of floating fibres drawn out by the fibres being drafted. Similarly when the number of fibres being or about to be drafted is reduced the gauging unit 97 operates through the transducer unit 96 to reduce the pressure between the

rollers

92 and 93 thereby reducing the fibre control to increase the number of floating fibres drawn out by the fibres being drafted. In this way the numbers of floating fibres are varied to compensate for variations in the number of fibres being drafted.

In an alternative arrangement shown in Fig. 10, the pneumatic gauging unit and transducer are replaced by a feeler arm or rod 99 attached to the arm 94, and on 10 which the rove bears thereby increasing the pressure between the

rollers

92 and 93, in proportion to the tension of the rove being drafted.

The operation of this unit is substantially the same as that described with reference to Fig. 9. 1

The apparatus for introducing prescribed slubs on thick places into the yarn according to the third application of the invention consists essentially of the apparatus described in relation to Figs. 1, 2, 5, 7, and 8 and 9 for the first application of the invention, but in which means is introduced for suddenly reducing the actual or effective length of the reach and/or the speed of the delivery rollers. In the application of the invention described with reference to Figs. 2, 5, 7, a valve is introduced into the supply of compressed air either to the gauging unit or to the transducer or both, whereby the supply of air is suddenly cut ofi and the air in the system is allowed to escape to the atmosphere. In the application of the invention described with reference to Fig. 2, the valve 100 is introduced in the tube carrying the supply of compressed air from the source of supply 20 to the restrictor 19. Normally the valve 100 allows the compressed air to flow from the supply 20 to the restrictor 19 and thence to the gauging unit 15 and the bellows 13 which is partially extended according to the pressure supplied by the gauging unit 15. When the valve 100 is suddenly operated the supply of compressed air from 20 is cut off and the air in the bellows 13 is released to atmosphere. The said bellows 13 contracts, and reduces the length of the path of the rove 1, from the

feed rollers

2, 2, to the drafting rollers 3, 3-, thereby increasing the supply of fibres to the nip of the drafting

rollers

3, 3, so forming a slub or thick place in the yarn. The valve 100 is then gradually restored to its normal, position and the pressure of air developed by the gauging unit and supplied to the bellows 13 increases to its normal value and the apparatus continues to spin level yarn as described with reference to Fig. 2. In the application of the invention as described with reference to Fig. 5 the valve 100 may be placed in the supply of compressed air to the gauging unit and the bellows 63 as described previously or a valve 101 may be introduced into the supply of compressed air to the orifice 58 as shown in Fig. 5. When the valve 101 is in its normal position compressed air is supplied to the orifice 58 from which it passes to the orifice 59 and the container 56 so that the said bellows is compressed by an amount corresponding to the extension of the bellows 63'. When the valve 101 is operated the air in the chamber 56 is allowed to escape through the orifice 59 and the bellows 55 is allowed to expand suddenly thereby lowering the plunger 54 and the arm 49 which simultaneously reduces the length of the reach and accelerates the

feed rollers

47, 48, thereby suddenly increasing the supply of fibres to the drafting rollers and producing a slub in the yarn. When the valve 101 is opened again compressed air passes through the

orifices

58 and 59 to the chamber 56 and the aparatus continues to work as described with reference to The third application of the invention is to introduce simultaneously on every end spinning on a frame, slubs in the yarn according to a prearranged pattern as shown in Fig. 11. A positively driven endless belt 102 having perforations 103 according to a prearranged pattern is passed between two

opposed orifices

104 and 105, the orifice 104 being connected to a supply of compressed air and the orifice 105 to a pneumatic bellows 106 which is normally contracted but which expands when a perfora tion is opposite the

orifices

104, 105. The bellows is connected to a plunger 107 which can be depressed against a spring 108 and which contains a hole 109 positioned so as to allow compressed air from a suitable source to pass from the tube 110 into the tube 111 when the bellows 106 are compressed, and to cut off the supply of air through 110 and allow air to flow from the tube- 111 through the tube 112, and escape into the atmos-v phere when the bellows expand. The tube 111 is connected to a plurality of drafting units 113, which may be of any of the forms described with reference to Figs. 1, 2, or 7 according to the first application of the invention. The operation of the apparatus is the same as that described above, namely when the endless belt 102 prevents air from flowing from the orifice 104 into the orifice 105, the bellows 106 is contracted and allows the supply of compressed air to flow from the supply through the tube 110 into the tube 111 and thence to each of the drafting units 113, which control the regularity of the yarn being spun according to the first application of the invention. When a perforation 103 passes between the

orifices

104 and 105 compressed air flows into the bellows 106 which expands and depresses the plunger 107 and allows the compressed air in the units 113 to escape through the

tubes

111 and 112 into the atmosphere, thereby suddenly and simultaneously increasing the supply of fibres to the drafting rollers of each of the said drafting units 113, and producing a slub in each of the yarns being spun. When the perforation 103 has passed the

orifice

104, 105, the bellows 106 contracts again and allows the supply of compressed air to flow to each of the drafting units 113, which resume their control of the short period irregularity of the yarns.

Alternately the bellows 106 may be connected to a pneumatic gauging unit of the type described with reference to Fig. 3(a) over which passes a slub yarn which it is desired to match. The said slub yarn is passed over the pneumatic gauging unit at the same speed as that of the delivery rollers of the spinning frame. As each slub passes the said gauging unit the bellows 106 is actuated to produce similar slubs in the plurality of yarns being spun.

The apparatus according to the fourth application of the invention reduces the long period variations in the drafted sliver or yarn by varying the speed of delivery of the

feed rollers

114, 115 which are positively driven at a constant speed (as shown in Fig. 12). The rove or twisted sliver 1 passes through a guide 116 placed behind the

tapered feed rollers

114, 115, and mounted on an arm 117 freely pivoted at 118 and acted on in opposite directions by the pneumatic bellows 119, 120 so that when the bellows 119 expands and the bellows 120 contracts the guide 116 moves the rove 1 laterally towards the larger diameter end of the tapered

rollers

114, 115 thereby increasing the rate of feed of the rove, similarly when the bellows 120 expands and the bellows 119 contracts the guide 116 moves the rove laterally towards the smaller diameter end of the tapered

rollers

114, 115 thereby decreasing the rate of feed of the rove.

The guide 116 is preferably positioned so that when the

bellows

119 and 120 contain air at the same pressure the rove is fed into a position half-way along the face of the tapered

rollers

114, 115. The rove leaving the tapered feed rollers passes through a pneumatic gauging unit 121 which provides a back pressure substantially proportional to the weight per unit length of the rove at this point and which may be of the type described with reference to Fig. 3(c) or of the type described hereinafter with reference to Fig. 13.

.The rove 1 also passes through a fibre control unit 122 which may be of the type described with reference to Fig. 2 or it may consist of any of the types described with reference to Figs. 1, 2, 4, 5, 9, or 11 according to the first, second and third applications of the invention; the rove is then fed to the drafting rollers 3.3.

Compressed air from a suitable source 123 is fed through a restrictor 124 to the gauging unit 121 and through a restrictor 125 to the bellows 120, and also through a very small restrictor 126 to the bellows 119. The said restrictor 126 should be sufiiciently small to give the bellows 119 a time constant of not less than 30 seconds.

The operation of the apparatus is as follows: When the rove 1 passing over or through the gauging unit 121 becomes heavier the gauging unit develops an increased back pressure which increases the pressure of the air in the bellows 120 which thereby starts to expand and move the guide 116 towards the small diameter end of the tapered feed rollers. After a certain delay period the rove 1 begins to follow the guide 116 and traverses towards the small diameter end of the feed rollers 114, thereby reducing the speed at which the rove is delivered by the feed rollers and increasing the draft so that the yarn emerging from the drafting rollers 3.3, remains at substantially the same weight per unit length as before. The bellows 119 only responds very slowly to the changes in air pressure owing to the small size of the restrictor 126 and the pressure of the air inside the said bellows varies as a running average of the rove which has passed the gauging unit 121 during a previous interval of time which should not be less than 30 seconds. In this way the long period variations of lengths up to about 50 yards are reduced or eliminated in the yarn but the overall average weight per unit length of a very long length of yarn is not affected and is determined by the average weight of the rove and the draft applied to the frame.

In an alternative form of the apparatus according to the fourth application of the invention and substantially as described with reference to Fig. 12 instead of being connected to the bellows through a restrictor 126 the bellows 119 may be connected to a supply of compressed air maintained at a constant pressure at a value which is substantially equal to the pressure which the air in the bellows 120 would have when the gauging unit 121 gauges the normal weight of the rove or the bellows 119 may be replaced by a compression spring of suitable strength. In these alternative forms the position of the rove 1 in the nip of the tapered

rollers

114, 115, is determined by the actual weight of the rove being gauged by the gauging unit 121 and not by the difference between this value and an average of the Weight per unit length of the rove which has passed over or through the gauging unit during the previous interval of time.

The position of the gauging unit 121 may be adjusted so that the time taken for a point on the rove 1 to pass from the said gauging unit to the drafting rollers is substantially the same as the average delay which occurs between an increase in the weight of the rove 1 traversing to its appropriate position on the tapered feed rollers. Alternatively, the said gauging unit may be incorporated in the guide 116 placed behind the feed rollers or it may be placed in any of the positions indicated for the gauging unit according to the first application of the invention as shown in Fig. 1.

When the apparatus as described with reference to Fig. 12 according to the fourth application of the invention is combined with apparatus substantially as described with reference to Figs. 1, 2, 4, 9, or 11, according to the first, second and third applications of the invention, the same gauging unit may be used for both the apparatus for controlling and reducing the long term variations and the apparatus for controlling or reducing the short term variations, or separate gauging units may be used for each apparatus.

An alternative form of gauging unit for providing a pneumatic pressure which varies substantially as the weight per unit length of the rove is shown diagrammatically in section in Fig. 13 consists of a member having a cylindrical hole 127 slightly flared at one end 128 through which the rove passes. In the wall of the hole is an annular space 129 the sides of which are set at an angle of about 45 to the axis of the cylindrical hole connecting to an annular chamber 130 to which compressed air is supplied through the tube 131. The gauging unit is self-threading since when the hole 127 is empty the air flows out of the orifice 132 and is drawn in through the.

orifice 128 consequently a free end of rove or sliver is sucked into the orifice 128 and emerges at the orifice 132.

The gauging unit shown in Fig. 13 when connected to a supply of compressed air through a suitable restrictor, develops a back pressure which increases substantially as the increase in weight per unit length of the rove over a limited range of rove weights, and a separate gauging unit must be used for different sizes of rove.

The apparatus shown diagrammatically in Fig. 14 for the fifth application of the invention to be used in conjunction with the first, second and fourth applications of the invention substantially as described with reference to Figs. 1, 2, 5, 7, 8, 9 and 12 to stop the delivery of the sliver or rove to the feed rollers when the said sliver or rove contains an excessive irregularity. It consists of a pneumatic capsule 133 connected by a tube 134 to t-e pneumatic gauging unit in any of the said applications, and operating to close a pair of electrical contacts 135 and 136 when the air pressure inside the said capsule exceeds a prescribed value. The electrical contacts are connected in series with a suitable low voltage electrical supply to a cutting unit substantially as described in the specification of our British Patent No. 716,370 and consisting of a solenoid 137 which acts on a soft iron slug 138 on an arm 139, pivoted at 140 and carrying a blade 141 which closes against an anvil 142 when the solenoid is energised.

The rove 1 passes between the blade 141 which is normally open and the anvil 142 before reaching the feed rollers. When the pneumatic gauging unit develops a pneumatic pressure which exceeds a prescribed value corresponding to the maximum weight per unit length of rove which could be compensated for by any of the aforesaid applications of the invention, the pneumatic capsule 133 expands sufliciently to close the contacts 135, 136 thereby energising the solenoid 137 which closes the blade 141 against the anvil 142 to cut or stop the rove from being fed into the feed rollers.

In an alternative arrangement one of the said contacts 135, 136 may be mounted on the transducers described with reference to Figs. 1, 2, 4, 5, 7, 8, 9 or on the arm 117 in Fig. 12 to cut or stop the rove when the movement of any of the said transducers exceeds prescribed limits.

It is understood that mechanical or wholly pneumatic stop motions may be used in conjunction with the said transducers, without departing from the scope of the invention.

In the following claims it is to be understood that the term sliver includes roves and yarns; that the term thickness includes weight per unit length or the tension and also a combination of two or more of the thickness, the weight per unit length, or the tension.

We claim:

1. In apparatus for drafting slivers composed of staple fibers, the combination with drafting rollers and feed rollers of a pneumatic gauging unit to measure the tension of the sliver positioned between the drafting rollers and the feed rollers to transmit continuously and automatically a signal whose magnitude is a function of the tension of the sliver, a guide member positioned between the feed rollers and the drafting rollers to vary the length of the path of the sliver, and a pneumatic transducer responsive to said signal and operative to alter the position of the guide member and vary the length of the path of the sliver between the feed rollers and the drafting rollers to control the degree of draft of the said point of the sliver.

2. In apparatus for drafting slivers composed of staple fibers, the combination with drafting rollers and feed rollers of a pneumatic gauging unit to measure the tension of the sliver positioned adjacent a point of the sliver between the drafting rollers and the feed rollers to transmit continuously and automatically a signal whose magnitude is a function of the tension of the sliver, a first driven roller positioned between the feed rollers and the drafting rollers, an arm, a second roller mounted on said arm to press the sliver against said first roller, and a pneumatic transducer responsive to said signal and operative to alter the position of said arm and vary the pressure between said first and second rollers to control the degree of draft of the said point of the sliver.

3. In apparatus for drafting slivers composed of staple fibers, the combination with a pair of drafting rollers and a pair of feed rollers, one of said pairs comprising a driven tapered roller, of a pneumatic gauging unit to measure the tension of the sliver positioned adjacent a point of the sliver between the feed rollers and the drafting rollers to transmit continuously and automatically a signal whose magnitude is a function of the tension of the sliver, a guide member to position the sliver along the nip of the tapered roller, and a pneumatic transducer responsive to said signal and operative to alter the position of the guide member and position the sliver along the nip of the tapered roller to control the degree of draft of the said point of the sliver.

4. In apparatus for drafting slivers composed of staple fibers, the combination with a pair of drafting rollers, a pair of feed rollers, a driven shaft and a gear wheel mounted on the shaft to drive one of said pairs of rollers, of an arm carried pivotally on said shaft, the pair of rollers driven by said gear wheel being mounted on said arm, a pneumatic gauging unit to measure the tension of the sliver positioned adjacent a point of the sliver between the feed rollers and the drafting rollers to transmit continuously and automatically a signal whose magnitude is a function of the tension of the sliver, and a pneumatic transducer responsive to said signal and operative to alter the position of said arm to control the degree of draft of the said point of the sliver.

5. In apparatus for drafting slivers composed of staple fibers, the combination with a pair of drafting rollers, a pair of feed rollers, a first gear wheel carried by one of the rollers of one of said pairs of rollers and a second gear wheel mounted on a shaft to drive said first gear wheel, of a frame mounted pivotally on said shaft, a differential gear carried by said frame, said first gear wheel engaging the differential gear and the differential gear engaging said second gear wheel, a pneumatic gauging unit to measure the tension of the sliver positioned adjacent a point of the sliver between the feed rollers and the drafting rollers to transmit continuously and automatically a signal whose magnitude is a function of the tension of the sliver, and a pneumatic transducer responsive to said signal and operative to alter the position of said frame to control the degree of draft of the said point of the sliver.

6. In apparatus for drafting slivers composed of staple fibers as defined in claim 3, a pneumatic delay member connected to said pneumatic gauging unit to transmit said signal after a delay in time, and a second pneumatic transducer connected to the delay member, the second pneumatic transducer being operative to alter the position of said guide member in response to said delayed signal to reduce long period variations in thickness of the sliver.

References Cited in the file of this patent UNITED STATES PATENTS 2,266,900 Owens et a1 Dec. 23, 1941 2,361,217 Lewis Oct. 24, 1944 2,378,595 Tasso June 19, 1945 2,407,100 Richardson Sept. 3, 1946 2,542,331 I-Iiensch Feb. 20, 1951 2,729,857 Cushing et a1. Jan. 10, 1956 2,746,093 Raper May 22, 1956 FOREIGN PATENTS 882,819 Germany July 13, 1953