US2737687A - Production of textile materials - Google Patents

Description

March 13, 1956 w. POOL ET AL PRODUCTION OF TEXTILE MATERIALS 2 Sheets-Sheet 1 Filed April 25, 1948 NOE 1' H I all.

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I. II: I I' I 'III lllll March 13, 1956 w. POOL ETAL PRODUCTION OF TEXTILE MATERIALS 2 Sheets-Sheet 2 Filed April 23. 1948 A -McGILL 5L w m ymw orneys United States Patent 2,737,687 PRODUCTION OF TEXTILE MATERIALS William Pool and Alexander McGill, Spondon, near Derby, England, assignors to Celanese Corporation of America, a corporation of Delaware Application April 23, 1948, Serial No. 22,806 Claims priority, application Great Britain April 30, 1947 14 Claims. (Cl. 19-.41)

This invention relates to the production of textile materials and particularly to the manufacture of staple fibre products, and is especially concerned with the conversion of a bundle or sliver of continuous filaments into a continuous product made of or containing staple fibre, without destroying the continuity of the bundle as a whole.

One method of converting a bundle of continuous artificial filaments into a continuous staple fibre product consists of passing the continuous filament bundle successively through two set of gripping rollers, the rollers of the second set being rotated at a higher peripheral speed than those of the first set so as to stretch the continuous filaments beyond their breaking point, the material emerging from the second set of gripping rollers in the form of a continuous product consisting of staple fibres of a maximum length not greatly exceeding the distance between the sets of gripping rollers. One disadvantage of this method of conversion is that the length of the staple fibres varies from the maximum downwards to a very short length, and the product appears to contain a greater proportion of short fibres than would be expected on the assumption that the breakage of the filaments occurs at points distributed at random over the distance between the sets of rollers. This, it now seems probable, is due to compacting of, and interference between the filaments of the bundle whereby the rear end of a freshly broken fibre does not proceed freely and independently forward to the second set of rollers, but is apt to be influenced by the surrounding filaments. Another disadvantage is that the fibres, having been formed by stretching continuous filaments beyond their breaking point, and deficient in extensibility in comparison with the filaments from which they were formed.

It has now been found that, if the filaments of a bundle of filaments are stretched almost up to their yield point and are then sharply and locally impacted, some of the filaments are apt to break at the point of impact. The yield point is defined as the point at which the ratio of an increment of strain to the increment of stress which produces it is equal to the ratio of breaking strain to breaking stress and, in textile materials generally, is far. short of the breaking point thereof. Nevertheless, although the filaments are not stretched nearly to the point of breaking under tensile stress, the sudden shock of impact produces a severance thereof at the point of impact, apparently under a local shear stress due to the inertia of the filaments and to their rigidity under the tension applied. It is an object of the present invention to make use of this property in an improved method of converting a bundle or sliver of continuous filaments into a continuous staple fibre product.

According to the present invention a process for the conversion of a bundle or sliver of continuous filaments into a continuous product made of staple fibres comprises gripping the filaments of the bundle at two spaced points, forwarding the gripped filaments from the first of said points towards the second at one linear speed, and from the second point onwards at a greater linear speed so as 2,737,687 Patented Mar. 13, 1956 to stretch said filaments between said points and, at a third point between said two points, subjecting the filaments to sharp and rapidly repeated impact so as to break, at said third point, some of the filaments that have been stretched to a degree substantially short of that at which they would break under tension. In order to produce the desired eifect it is necessary that the impact should be effected by an unyielding member moving with a sub stantial velocity, e. g. exceeding 10 ft. per second, and preferably exceeding 15 or 20 ft. per second. As, in processes of this kind, the feed rate of the filaments, i. e. their linear speed at the first of the two points is of the order of 20 to 200 inches per minute, it will be seen that the velocity of impact is of a higher order, being at least thirty times and preferably -200 or more times the rate of feed of the filaments. The frequency of impact should be such, in relation to the feed and delivery rates, that each filament receives several impacts while it is under tension, i. e. in the interval between the gripping of the leading end of a filament at the second point and the breaking of the same filament at the third point when it has been stretched almost to its yield point, and the frequency in time of the impacts to produce this result may, for example, range from 500 impacts per minute upwards.

By the means described above not only is the breaking of the filaments at the point of impact rather than at any other point encouraged, giving a much narrower distribution of staple lengths than breakage at random between the gripping devices, but also the bundle is kept in a state of continual agitation which prevents or reduces interference between the filaments of the bundle. Further, the resulting fibres have a higher extensibility, more nearly comparable with that of the original filaments. This characteristic, and the fact that the broken ends of the filaments have not the reduction in area typical of a tensile fracture, support the suggestion that the filaments are broken under shear stress. The broken ends have, moreover, a tendency to bend or curl slightly, which improves the mutual cohesion and other spinning properties of the resulting fibres.

An apparatus in accordance with the invention, suitable for carrying out the process described above, comprises two gripping and forwarding devices, means for driving both said devices so that the second device forwards a filament bundle gripped thereby at a speed substantially greater than the first, an impacting member presenting a narrow edge transverse to a bundle of filaments proceeding from one device to the other, and means for rapidly vibrating said member so that said edge moves laterally to cross the direct line of travel of said bundle from one device to the other.

As the gripping and forwarding devices, a set of nip rollers can be used, through the nip of which the filament bundle is guided, and between which it is gripped by pressure between the rollers. Alternatively, a pair of roller-supported aprons may be used as a device to grip and forward the filament bundle, or one such apron in combination with a plain roller. It is generally desirable that at least one of the surfaces between which the filament bundle is gripped in the gripping and forwarding device should be a surface of slightly resilient character, as is provided by an apron, or by a leather-covered or rubber-covered roller.

One convenient form of vibrating means suitable for the purposes of the present invention is a molding box vibrator as commonly used on moulding boxes in foundries, e. g. a No. 5 mould-box vibrator as marketed by The Consolidated Pneumatic Tool Company Limited of London, England; another form is a vibrator such as is used for vibrating the doffer knife of a carding engine, e. g. as described on page 213 of the publication Wool Carding" by James Bradley, published by Emmott & Company of Manchester, England, 1921. Vibrators of this kind can be adapted to actuate suitable impacting members, e. g. sheet metal T members or stirrup-shaped members, mounted so as to present a narrow edge to the filaments.

On leaving the second gripping and forwarding device the staple fibre product may be subjected on its way to collection, to any desired treatment suitable to the condition of the material. For example, the product may be passed over or through a moistening device for the application of an anti-static lubricant or other finish. If an anti-static lubricant or finish is required, it is often better, especially where a very heavy bundle or tow of continuous filaments of a total denier of the order of 100,000 or more is to be converted into a heavy staple fibre product or top, to apply the finish to the fibres at this stage than to apply it to the continuous filaments before conversion. since apparently the tendency of the filaments to become electrified assists in preventing undue compacting thereof in the gripping and forwarding devices. Where a lighter bundle is to be converted into a short-staple roving, or directly into a coarse yarn, however, it is preferable to use a filament bundle that is already treated with finish, since in this case difficulties due to compacting are less likely to arise.

The staple fibre product delivered by the second gripping and forwarding device can be collected in any con venient way. Thus a heavy product or top can be collected in a rotating coiler can or sliver can, in which case the product can be passed to the can through a crimping device of the stufiing-box type to impart a crimp or curl to the fibres thereof which facilitates the subsequent processing of the material and improves the properties of the yarn into which the product is finally made. A lighter product of the type of a roving can be collected on a bobbin by means of a fiyer-twister which imparts a slight twist to the product. If the process is used, however, for the direct production of a material of the nature of a coarse yarn. the staple fibre product can be collected on a bobbin by means of a ring-spinning device, whereby a greater degree of twist is imparted to it in the course of its collection. In any of the above cases the staple fibre product may be passeed through a false twisting device at one or more stages in its progress, to assist in maintaining its cohesion as a continuous product.

By way of example some forms of apparatus in accordance with the present invention will not be described in greater detail with reference to the accompanying drawings in which,

Fig. 1 is a sectional side evelation and Fig. 2 is a plan view of one form of apparatus, adapted for the production of a staple fibre top,

Fig. 3 is an enlarged view of part of Fig. 1,

Fig. 4 shows the vibrator member shown in Figs. 1 to 3,

Fig. 5 is a diagrammatic side elevation of another form of apparatus, adapted for the production of a roving, and

Fig. 6 is a similar diagrammatic side elevation of a third form of apparatus, adapted for the direct production of a heavy yarn.

The apparatus shown in Figs. l-4 comprises a source of supply of bundles of continuous filaments in the form of a stand 2 for a number of coiler cans 3, e. g. 10, each holding a thick bundle or sliver 1 of continuous filaments. After each bundle 1 has passed round a guide 4 disposed above its coiler can, the bundles are gathered together and passed between a pair of pins 5 by which the several bundles 1 are assembled in the form of a thick, fiat ribbon 6. The ribbon 6 then passes over and under a set of three flattening bars 7, and then through two sets of three evening and tensioning rollers 8, 9, 10, each set comprising two spaced rollers 8, 10 carried in bearings 11 and a third and larger roller 9 riding on and between the rollers 8, 10. The ribbon 6 of continuous filaments passes under the first roller 8, over the riding roller 9 and under the second roller 10.

The ribbon or sheet then passes horizontally to a set of gripping rollers 12, 13 which consists essentially of a pair of rollers mounted one vertically above the other, the upper roller 12 being heavily pressed down on the lower roller 13 by means of strong springs 14 acting on vertically sliding bearing blocks 15 by which the roller 12 is carried. Round the lower roller 13 is an apron 16 which is held under tension by a third or jockey roller 17 lying below and behind the lower roller 13. The path of the filaments 6 from the first set of breaking rollers 12, 13 to the second set 19, 20 is inclined downwards at about 30 to the horizontal, so that the filaments 6 remain in contact with the lower roller 13 for a short distance after passing through the nip between the rollers 12, 13.

The second set of gripping rollers 19, 20 is similar to the first except that the top roller 19 is not directly above, but somewhat forward of the lower roller 20, so that the filaments 6 coming from the first set of rollers 12, 13 enter directly into the nip of the second pair 19, 20. Further, the apron 21 of this set passes round the top roller 19 instead of the bottom roller and is held under tension by a jockey roller 22 lying above and in front of the top roller 19. The evening or tensioning rollers 8, 9, 10 are driven at a speed about 2% slower than the first set of gripping rollers 12, 13, and the second set of gripping rollers 19, 20 are driven three to ten times as fast as the first set 12, 13, so as to extend the filaments between the first and second sets of gripping rollers.

Between the two sets of rollers 12, 13 and 19, 20 the thick ribbon or sheet 6 of filaments passes through the aperture 25 (Fig. 4) of a stirrup-shaped sheet metal vibrator member 26, the said aperture having one straight edge 27 adapted, in the motion of the vibrator, to engage with the filaments. The vibrator member is arranged to vibrate at a speed of from 1,0005,000 oscillations per minute by means of a No. 5 mould-box vibrator as produced by The Consolidated Pneumatic Tool Company Limited.

Each filament that is gripped by both sets of rollers, 12, 13 and 19, 20 is stretched between the two sets by the excess of the speed of the second set over that of the first. Long before the filament would break under tension, however, by reason of being stretched in this way, it is broken under shear stress by one of the blows being delivered at frequent and regular intervals by the edge 27. The newly formed end of the continuous filament, which filament is now gripped only by the rollers 12, 13, is fed forward till it is again gripped by the rollers 19, 20, and the cycle is repeated, the other continuous filaments in the band 6 having meanwhile gone through a similar cycle. The product 29 delivered by the rollers 19, 20 is a staple fibre product, consisting of the portions successively broken under shear stress from the ends of the continuous filaments 6.

Beyond the second pair of gripping rollers 19, 20, the staple fibre product 29 passes immediately through a false-twist tube 30, and then over a lubricating roller 31. The roller 31 has an etched surface, and rests on a smaller roller 32 running in a trough 33 in which a constant level of a lubricating finish is maintained, the staple fibre product 29 being guided by a third roller 36 in contact with the roller 31. The roller 36 is adapted to be automatically lifted when the machine stops so that the slight tension in the product 29 lifts it clear of the roller 31 and prevents excessive local lubrication. The staple fibre product then proceeds to the rotating funnel 37 of a further false twist device 38 leading it to nip rollers 39 disposed over the top of a rotating coiler can 44, in which the continuous product 45 is collected as a staple fibre top.

The following is given as an example of the way in which the apparatus described above can be used.

Example Ten slivers 1, each of 34,000 denier and consisting of 7550 cellulose acetate filaments of 4.5 filament denier are drawn from the sliver cans 3 and assembled to form the ribbon 6, which is 5" in width and has a total denier of 340,000. The first pair of gripping rollers 12, 13 are driven at a speed of 28.5" per minute and the second pair at 142.5" per minute, giving a draft of 5. The vibrator member 26 is vibrated at the rate of 2,000 oscillations per minute and is disposed 2 /2" from the nip of the rollers 12, 13 and 5" from the nip of the rollers 19, 20. so as to produce a staple length of just over 5 in the resulting product. The product 29 delivered to the can 44 is a staple fibre top of 68,000 denier.

The form of apparatus diagrammatically shown in Fig. 5 is a converted roving frame in which the starting material 50 is a heavy sliver that has already been treated with an antistatic finish and is drawn from a sliver can 51 by the rear rollers 52 of the machine. From the rear rollers 52 the material passes to the front rollers 53, the intermediate rollers being omitted for the purpose of the present invention, and replaced by vibrator member 26 of the kind described with reference to Figs. 1 to 4, driven by a pneumatic vibrator 28 disposed above the rollers 52, 53. From the front rollers 53 the staple fibre product or roving 54 is drawn through a false twisting funnel 55 by means of a pair of light Bakelite rollers 56, and delivered to a flier-spinning device 57 of the kind commonly employed in roving frames, by means of which the roving is wound on the bobbin 58. Since the twist inserted by the flier-spinning device 57 is low, the false twisting funnel 55 and rollers 56 are desirable for the purpose of condensing the roving 54 and preventing it from licking round the front rollers 53.

As an example of the Way in which the apparatus shown in Fig. 5 may be employed, the sliver 50 may be of 4,000 denier, consisting of 850 cellulose acetate filaments of a filament denier of 4.7. The pairs of rollers 52, 53 are set 3.5" apart and the vibrator member 26 is disposed 1.4" from the rear rollers 52. The rear rollers 52 are rotated at 12" per minute and the front rollers 53 at 78.5" per minute, giving a draft of 6.6. The vibrator member 26 is driven at 2,000 oscillations per minute. The resulting product is a lightly twisted roving of about 600 denier (8.8s cotton count) and of an average staple length of 2.1".

The apparatus diagrammatically shown in Fig. 6 is designed for the direct production from continuous filaments of a heavy staple fibre yarn. A continuous filament bundle 60 previously treated with an anti-static finish is drawn from a sliver can 61 and passes through a guide 62 to the rear rollers 63 of a ring frame. From the rear rollers 63 the material passes directly to the front rollers 64 of the ring frame, the intermediate rollers being replaced, as in Fig. 5, by a vibrator blade 26 operated by a pneumatic vibrator 28. From the front rollers 64 the staple fibre product 65 proceeds to the lappet guide 66 of a ring-spinning device 67 by means of which the product is twisted into a coarse yarn and wound on the bobbin 68. The twist imparted by the rotation of the bobbin 68 runs up to the front rollers 64 and effectively prevents licking of the product 65 on the rollers 64, so that the false twisting tube 55 and auxiliary rollers 56 described with reference to Fig. 5 are not called for.

As an example of the way in which the apparatus shown in Fig. 6 may be used, the continuous filament bundle 60 may have a denier of 1764, consisting of 392 filaments of 4.5 denier each. The rear rollers 63 are driven at a speed of 16.7" per minute and the front rollers 64 at a speed of 250" per minute, giving a draft of 15. The vibrator member 26 is disposed 2%" behind the front rollers 64 and is operated at 3,000 vibrations per minute. The bobbin 68 is driven at 2,040 revolutions per minute. The resulting product is a coarse yarn of about denier (45s cotton count) having about 8 turns per inch twist.

Having described our invention, what we desire to secure by Letters Patent is:

l. Process for the conversion of a bundle of continuous filaments into a continuous product made of staple fibres, said process comprising gripping the filaments of the bundle at two spaced points, forwarding the gripped filaments from the first of said points towards the second at one linear speed, and from the second point onwards at a greater linear speed so as to stretch said filaments between said points, and at a third point between said two points, subjecting the bundle of filaments to sharp and momentary impacts repeated at least 500 times per minute, each impact being distributed over the whole width of said bundle so as to break, at said third point, some of the filaments that had been stretched to a degree substantially short of that at which they would break under tension.

2. Process according to claim 1 comprising forming the bundle into a flat ribbon before subjecting it to conversion.

3. Process according to claim 2 comprising assembling a number of slivers of continuous filaments in the form of a fiat ribbon constituting a heavy bundle.

4. Process according to claim 1 comprising applying a finish to the staple fibre product as it is forwarded from the second point.

5. Apparatus for the conversion of a bundle of continuous filaments into a continuous product made of staple fibres, said apparatus comprising two gripping and forwarding devices, means for driving both said devices so that the second device forwards a filament bundle gripped thereby at a speed substantially greater than the first, an impacting member presenting a thin but blunt edge ex tending transverse to and across the whole width of a bundle of filaments proceeding from one device to the other, and means for rapidly vibrating said member so that said edge moves laterally to cross the direct line of travel of said bundle from one device to the other with an average velocity at least 30 times the forwarding speed of the first device and with a vibration-frequency of at least 500 per minute.

6. Apparatus according to claim 5 wherein each gripping and forwarding device comprises a par of nip rollers, adapted to be pressed together upon a bundle of filaments passing between said rollers.

7. Apparatus according to claim 5 wherein each gripping and forwarding device comprises a member having a surface of resilient character, against which surface the bundle of filaments is pressed to grip the bundle.

8. Apparatus according to claim 5 comprising means for applying a finish to the staple fibre product as it is delivered from the second gripping and forwarding device.

9. Apparatus according to claim 5 comprising, as each of the gripping and forwarding devices, a pair of nip rollers adapted to be pressed together upon a bundle of filaments passing between said rollers, and a resilient apron passing round one of said rollers and through the nip between said rollers.

10. Process for the conversion of a bundle of continuous filaments into a continuous product made of staple fibres, said process comprising gripping the filaments of the bundle at two spaced points, forwarding the gripped filaments from the first of said points towards the second at one linear speed, and from the second point onwards at a greater linear speed so as to stretch said filaments between said points, and at a third point between said two points. subjecting the bundle of filaments to sharp and momentary impacts repeated at least 600 times per minute, each impact being distributed over the whole width of said bundle so as to break, at said third point, some of the filaments that had been stretched to a degree substantially short of that at which they would break under tension.

11. A process of converting continuous filaments moving in a substantially straight line path into filaments of staple length, which comprises subjecting the filaments to transverse oscillations repeated at least 500 times per minute which simultaneously subjecting them to a stretch in excess of their extensibility.

12. A process of converting continuous filaments into filaments of staple length which comprises subjecting the filaments to transverse oscillations repeated at least 500 times per minute without substantial bending thereof while simultaneously breaking and drafting the filaments.

13. Process for the conversion of a bundle of continuous filaments into a continuous product made of staple fibers, said process comprising gripping the filaments of the bundle at two spaced points, forwarding the gripped filaments from the first of said points towards the second at one linear speed, and from the second point onwards at a greater linear speed so as to stretch said filaments between said points, and at a third point between said two points, subjecting the bundle of filaments to transverse oscillations repeated at least 500 times per minute, each oscillation being distributed over the whole width of said bundle so as to break, at said third point, some of the filaments that had been stretched to a degree substantially short of that at which they would break under tension.

14. Apparatus for the conversion of continuous filaments into a continuous product made of staple fibers, said apparatus comprising two gripping and forwarding devices, means for driving both said devices so that the second device forwards a filament bundle gripped thereby at a speed substantially greater than the first, a member extending across the whole width of the bundle of filaments proceeding from one device to the other, and means for moving said member with an average velocity at least times the forwarding speed of the first device and with a vibration frequency of at least 500 per minute to impart transverse oscillations to the bundle of filaments.

References Cited in the file of this patent UNITED STATES PATENTS 1,914,491 Dreyfus et a1 June 20, 1933 2,064,279 Taylor et al Dec. 15, 1936 2,177,929 Lambert Oct. 31, 1939 2,180,172 Schmitt Nov. 14. 1939 2,213,793 Gibson Sept. 3, 1940 2,278,032 Youngman Mar. 31, 1942 2,419,320 Lohrke Apr. 22, 1947 2,438,469 Wilkie Mar. 23, 1948 FOREIGN PATENTS 876,936 France Aug. 24, 1942

Claims (1)

1. PROCESS FOR THE CONVERSION OF A BUNDLE OF CONTINUOUS FILAMENTS INTO A CONTINUOUS PRODUCT MADE OF STAPLE FIBRES, SAID PROCESS COMPRISING GRIPPING THE FILAMENTS OF THE BUNDLE AT TWO SPACED POINTS, FORWARDING THE GRIPPED FILAMENTS FROM THE FIRST OF SAID POINTS TOWARDS THE SECOND AT ONE LINEAR SPEED, AND FROM THE SECOND POINT ONWARDS AT A GREATER LINEAR SPEED SO AS TO STRETCH SAID FILAMENTS BETWEEN SAID POINTS, AND AT A THIRD POINT BETWEEN SAID TWO POINTS, SUBJECTING THE BUNDLE OF FILAMENTS TO SHARP AND MOMENTARY IMPACTS REPEATED AT LEAST 500 TIMES PER MINUTE, EACH IMPACT BEING DISTRIBUTED OVER THE WHOLE WIDTH OF SAID BUNDLE SO AS TO BREAK, AT SAID THIRD POINT, SOME OF THE FILAMENTS THAT HAD BEEN STRETCHED TO A DEGREE SUBSTANTIALLY SHORT OF THAT AT WHICH THEY WOULD BREAK UNDER TENSION.

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