Title of Invention

AN ARRANGEMENT FOR MECHANICAL CONDENSING OF A FIBRE STRAND

Abstract

The invention relates to an arrangement (1) for mechanical condensing of a fibre strand (3) comprising a condensing zone (2) which is arranged downstream of a drafting unit (4) being bordered by a nipping line (13); and a condensing element (15) disposed upstream of the nipping line (13) formed of a delivery roller pair (11, 12), the condensing element (15) having a groove-like condensing slit (16) which tapers laterally in transport direction A, on the base (17) of said condensing slit (16) the fibre strand (3) is guided in a sliding manner, characterized in that the condensing slit (16; 516; 716; 1016) has a base (17; 517; 717; 1017) which is convexly shaped in transport direction (A) and in that the base (17; 517; 717; 1017) is continued at the end of the condensing slit (16; 516; 716; 1016) by a similarly convexly shaped fibre guiding surface (18; 518; 718; 1018) of the condensing element (15; 515; 715; 1015).

Full Text

FIELD OF THE INVENTION The present invention relates to an arrangement for mechanical condensing of a fibre strand, comprising a condensing element arranged upstream of a nipping line of a delivery roller pair, which condensing element comprises a groove-like condensing slit which tapers laterally in transport direction, on the base of said condensing slit the fibre strand is guided in a sliding manner. BACKGROUND OF THE INVENTION An arrangement of this type is prior art in the Swiss published Patent 277 003. The known condensing element has a plane base and is arranged between two roller pairs without touching either of them. This arrangement is designed to improve the two-ply or spinning process. The improvement lies apparently in the fact that the fibre strand is laterally bundled when travelling through the condensing slit, so that at the nipping line of the delivery roller pair, a relatively narrow fibre strand having a reduced spinning triangle exits, thus resulting in a better quality thread. The disadvantage of the known arrangement is that the bundled fibre strand can spread out again somewhat before it reaches the nipping line of the delivery roller pair, so that the desired result is only partly achieved. GB 577094 discloses a fibre controlling means for textile drafting apparatus which comprises a guide 16 of substantially U- section having its flanking sides progressively spaced closer to- gether from the point of entry of the fibres, the internal walls 19 and base surface 20 being convex so to guide the leading tips of the selvedge fibres positively into the main body of the sliver, the guide being chamfered at 21* 22 so that it may be positioned as near as possible to the drafting rollers 6, 12. The guides 16, which may be of porcelain, glass, synthetic resin or a metal pressing, may be mounted in pairs on a traverse bar 15 being carried by relatively adjustable members 17, 18. US 2,203,423 discloses a device for treating textile slivers or ravings comprising a body member having a narrow floor portion with upwardly extending side walls, the ends of said body being open, said floor portion being upwardly arched so as to extend bridging the space between one set of draft rolls and another set of draft rolls in the normal operating position of the device in a drawing mechanism, said side walls converging from the rear toward the front ends of the device for condensing the sliver in passing therebetween, the opposed inner side faces of said side walls being of convexedly curved form in cross section for lifting up and forcing over the body portion of the sliver the fibers lying close to and at the marginal portions of the sliver as the latter advances through the device* the curvature of said inner faces of the side walls extending in a continuous curve upwardly from their meeting line with the floor portion of distance of a at least the average thickness of a sliver when the same is acted upon by said walls in passing through the device. OBJECT OF THE INVENTION I is an object of the present invention to guide the fibre strand, bundled in the condensing slit, to the nipping line in its condensed form without the fibre spreading out again. SUMMARY OF THE INVENTION According to this invention there is provided an arrangement for mechanical condensing of a fibre strand comprising a condensing zone which is arranged downstream of a drafting unit being bordered by a nipping line and a condensing element disposed upstream of the nipping line formed of a delivery roller pair, the condensing element having a groove-like condensing slit which tapers laterally in transport direction A, on the base of said condensing slit the fibre strand is guided in a sliding manner. The condensing slit has base which is convexly shaped in transport direction (A) and in that the base is continued at the end of the condensing slit by a similarly convexly shaped fibre guiding surface of the condensing element. In the case of purely mechanical fibre condensing, the fibre strand to be condensed is drawn through a tapering and continuously curved condensing slit, whereby the fibre strand is increasingly condensed. As the fibre strand glides over a surface which is convex in design and which forms the base of the condensing slit, a certain drafting force acts on the fibres due to the curve of the base, which drafting force leads to a normal force which presses the fibres to the base of the slit. This normal force has, as a consequence, a fractional force, which prevents the condensed fibre strand from spreading out again during transport. The base of the slit is preferably V-shaped in cross section. This results in a particularly intensive condensing. In an embodiment of the present invention, the base of the slit is continued at the end of the condensing slit by a fibre guiding surface, also convex in shape, of the condensing element. As a result, when the fibres of the fibre strand exit out of the condensing slit, they continue to be on a curved surface. Due to the occuring drafting forces, the fibres are pressed onto this curved surface, whereby in connection with the hereby occuring friction, a spreading out of the fibre strand in transverse direction is avoided, even when it leaves the condensing slit. It is hereby advantageous when, before it reaches the nipping line, the fibre strand is guided longitudinally along a part of the periphery of a delivery roller of the delivery roller pair. In the case of this delivery roller, an upper roller or a base roller can be involved here. Thus the fibres remain under a certain tension downstream of the fibre guiding surface, in that they continue to lie on a curved surface, which prevents the loss of the condensing effect. It is advantageous when the curved condensing element is hereby pressed against one of the delivery rollers. In a further embodiment of the present invention, a similarly convex-shaped intake guiding surface of the condensing element can precede the base of the slit at the start of the condensing slit, which intake guiding surface is pressed against a nipping roller of a nipping roller pair arranged upstream of the condensing element. This is not absolutely necessary for condensing, but results in the advantage that the condensing element can be better aligned along this nipping roller. The pressure of the fibre guiding surface and/or the intake guiding surface can occur by means of a preferably adjustable loading spring at the relevant delivery roller or nipping roller. The condensing element can be so designed that the condensing slit can be formed by lateral ribs or the like. The condensing slit can, however, also be molded into a condensing element made preferably of ceramic. It is advantageously provided that the length of the slit base, including a possibly present fibre guiding surface and an intake guiding surface, corresponds to the average fibre lengths of the fibre strand. The condensing element can be arranged at different places relative to a drafting unit. In one embodiment it is provided that the condensing element is arranged downstream of the drafting zone of a drafting unit. Alternatively it can be provided that the condensing element is arranged in the last drafting zone of a drafting unit. An advantageously designed embodiment is then possible when the condensing element, together with further condensing elements, is arranged on a guide rail which extends along a number of spinning positions. It can also be provided that the condensing element is mounted on a top weighting arm of a drafting unit. BRIEF DESCRIPTION OF THE DRAWINGS These and further objects, features and advantages of the present invention will become more readily apparent from the following detailed description thereof when taken in conjunction with the accompanying drawings wherein: Figure 1 is a partly sectional side view of a first embodiment according to the present invention, whereby the condensing element is arranged downstream of a drafting unit, Figure 2 is a view in the directionof arrow II of Figur 1, whereby several components have been omitted for reasons of clarity, Figure 3 is a cross section along the intersectional surface Ill-Ill of Figure 2, Figure 4 is a cross section along the intersectional surface IV-IV of Figure 2, Figure 5 is a depiction similar to Figure 1, in a second embodiment according to the present invention, Figure 6 is a schematic depiction to illustrate the present invention, Figure 7 is a depiction similar to Figure 1 showing a third embodiment according to the present invention, whereby the condensing element is arranged in the last drafting zone of a drafting unit, Figure 8 is a view in the direction of the arrow VIM of Figure 7, Figure 9 is a view similar to Figure 7 of a further embodiment of the present invention. Figure 10 is a view similar to Figure 7 in connection with a drafting unit embodiment having only one guiding apron. DETAIL DESCRIPTION OF THE INVENTION An arrangement 1 according to Figures 1 to 4 for mechanically condensing a fibre strand 3 comprises a condensing zone 2, which is arranged downstream of a drafting unit 4. In a known drafting unit 4 of this kind, the sliver or roving 5 is drafted to the desired degree in transport direction A. Of the drafting unit 4 only the front roller pair 6, 7 as well as an apron pair 8, 9 arranged upstream thereof 5 are shown. The front roller pair 6, 7 comprises a driven base roller 6 and a top roller 7. The drafting zone of the drafting unit 4 ends at the front nipping line 10 of the front pair 6, 7. If a drafted fibre strand 3 is imparted a spinning twist directly downstream of the front nipping line 10» a relatively wide spinning triangle would occur at the front nipping line 10, which would come about because the drafted fibre strand 3 leaves the front nipping line 10 having a relatively large width and is twisted to a thread having a relatively small diameter. The spinning triangle then comprises lateral fibres, which contribute little or nothing to the tensile strength of the spun thread so that they are not properly bound into the twisted thread. For this reason the so-called condensing zone 2 is arranged downstream of the drafting unit 4, which condensing zone 2 is in turn bordered by a nipping line 13. This nipping line 13 is formed by a delivery roller pair 11, 12, which comprises a driven delivery roller 11 and a top roller 12. Downstream of the nipping line 13 the twisted thread 14 is formed, in that it is fed in delivery direction B to a twist device (not shown), for example a ring spindle. With regard to the spinning twist, the nipping line 13 acts as a twist block, so that the condensing zone 2 remains twist-free. The thread 14 spun in this way is then more even, tear-resistant and less hairy due to the reduced spinning triangle at the nipping line 13. The arrangement 1 functions in a purely mechanical way comprises a condensing element 15 made preferably of ceramic, and which is arranged between the front nipping line 10 and the nipping line 13, said condensing element 15 having a groove-like condensing slit 16 laterally tapering in transport direction A. The condensing zone 2 is thus located downstream of the drafting zone of the drafting unit 4. According to the present invention the condensing slit 16 has in transport direction A a convexly designed slit base 17, over which the fibre strand 3 to be condensed is guided in a sliding manner. The slit base 17 has a preferably V-shaped design in cross section. The fibre strand 3 is drawn in transport direction A through the tapering, continuously curved condensing slit 16, whereby said fibre strand 3 is subject to a certain tension, which pushes the fibre strand 3 into the slit base 17. Due to these forces, the fibres of the fibre strand 3 always move in the slit base 17 of the V-shaped condensing slit 16 and are continuously condensed along the tapering condensing slit 16. It lies in the nature of the condensing slit 16 that it cannot approximate the nipping line 13. In order, however, that the fibre strand 3 does not laterally spread out again upstream of the nipping point 13 after it has left the condensing slit 16, it is provided that the slit base 17 is continued at the end of the condensing slit 16 by an similarly convex-shaped fibre guiding surface 18 of the condensing element 15. When the fibre strand 3 exits the condensing slit 16, the fibres continue to be subject to a tension on a curved surface. Due to the occuring drafting forces, they are pressed onto this surface, whereby, together with the friction occuring in transverse direction, the fibres of the already condensed fibre strand 3 are prevented from moving apart again. Directly downstream of the fibre guiding surface 18, the fibre strand 3 is guided along a part of the periphery 19 of the top roller 12 of the delivery roller pair 11, 12 before it reaches the nipping line 13. As the periphery 19 is also a curved surface, the condensed fibre strand remains in its condensed state until it reaches the nipping point 13, whereafter it is then twisted to a thread 14. It is hereby advantageous when the fibre guiding surface 18 of the condensing element 15 is pressed in a springy way to the top roller 12 of the delivery roller pair 11, 12. A nipping line 20 thus arises between the fibre guiding surface 18 and the periphery 19 of the top roller 12. Accordingly, an intake guiding surface 21 of the condensing element 15, also convexly shaped, can precede the slit base 17 at the start of the condensing slit 16, which intake guiding surface 21 is in turn pressed in a springy way to the top roller 7 of the front roller pair 6, 7 of the drafting unit 4. A further nipping line 22 is formed between the intake guiding surface 21 and the top roller 7. The loading spring 23 schematically shown in Figure 1 is preferably adjustable. It is so designed that the condensing element 15 aligns itself in relation to the two top rollers 7 and 12. The condensing slit 16 of the condensing element 15 is formed in the present case by lateral ribs 24 and 25. The length of the slit base 17 including the fibre guiding surface 18 and the intake guiding surface 21 is measured in such a way that it corresponds to the average fibre length of the fibre strand 3. The condensing element 15 can be arranged, together with further condensing elements (not shown), on a guide rail 26, which extends along a number of spinning positions. The embodiment of the present invention according to Figure 5 corresponds to a great extent to that in the Figures 1 to 4, the one difference being that in Figure 5 a condensing element 515 is provided, which is pressed not to the top rollers 7 and 12, but rather to the respectively driven base rollers 6 and 11. Thus nipping lines 520 and 522 are formed, whereby the fibre guiding surface 518 is pressed to the base roller 11 and the intake guiding surface 521 is pressed to the base roller 6. The fibre strand 3 is here also drawn over the convexly shaped slit base 517 of the condensing slit 516 while subject to tension. The distribution of forces are demonstrated with the aid of Figure 6, which forces prevent the condensing process of the already condensed fibre strand 3 being reversed. The delivery roller pair 11, 12 can be seen together with the final nipping line 13, as well as a preceding fibre guiding surface 518, which is pressed to the base roller 11 of the delivery roller pair 11, 12 at the nipping line 520. As a result of the curve of the delivery roller 11, drafting forces Z1 and Z2 act on the fibre strand 3, from which normal forces N result, which press the fibre strand 3 to the periphery 519 of the driven base roller 11. A friction arises therefrom in transverse direction, which prevents the already condensed fibre strand 3 from moving laterally apart, that is transversely to the transport direction A. Thus the condensing effect remains present when the fibre strand 3 leaves the condensing slit 516 and has not yet reached the nipping line 13. According to the variation in Figures 7 and 8, a condensing element 715 is provided which is located in the last drafting zone 727 of a drafting unit 704. It is hereby preferably arranged on a top weighting arm 728 of the drafting unit 704. A base apron table 729, arranged upstream, can be seen, which guides the base apron 8 and on which the condensing element 715 is indirectly supported by a supporting device 730. The condensing element 715 is supported on a nipping line 720 on the periphery 719 of the driven base roller 6 of the front roller pair 6, 7 of the drafting unit 704. The condensing slit 716 of the condensing element 715 is again convexly shaped and graduates into a fibre guiding surface 718, which is disposed at the nipping line 720 on the base roller 6. The embodiment of the present invention shown in Figure 9 corresponds to a great extent to the embodiment shown in Figure 7, the one difference being that there is a small gap between the fibre guiding surface 718 and the periphery 719 of the driven base roller 6. As long as this gap is very narrow, the condensed fibre strand 3 cannot expand again before it reaches the periphery 719. According to a further embodiment shown in Figure 10, a special drafting unit 1004 is provided in whose last drafting zone 1027 the condensing element 1015 is arranged. It is again supported on the driven base roller 6 of the front roller pair 6, 7 of the drafting unit 1004. Otherwise there is no significant difference to the embodiment as shown in Figure 7. According to Figure 10, a drafting unit 1004 is provided which does not comprise a base apron, but rather only an upper apron 1009 arranged upstream of the front roller pair 6, 7. This upper apron 1009 loops an apron pressure roller 1032, to which the sliver or roving 5 is fed in transport direction A. The upper apron 1009 acts together with a base roller 1031 having a relatively large diameter, on the periphery of said base roller 1031 the upper apron 1009 is guided until shortly before reaching the condensing element 1015. As soon as the fibre strand 3 to be condensed, still inside the drafting zone 1027, reaches the slit base 1017 of the condensing element 1015, said fibre strand 3 is drafted over a curved surface, which is formed downstream of the slit base 1017 by a fibre guiding surface 1018 of the condensing element 1015 and thereafter by the periphery 719 of the base roller 6. It is should be noted that the condensing element 1015 is pressed to the base roller 6 via a holding device 1034. ME CLAIM : 1. An arrangement (1) for mechanical condensing of a fibre strand (3) comprising a condensing zone (2) which is arranged downstream of a drafting unit (4) being bordered by a nipping line (13); and a condensing element (15) disposed upstream of the nipping line (13) formed of a delivery roller pair (11, 12), the condensing element (15) having a groove-like condensing slit (16) which tapers laterally in transport direction A, on the base (17) of said condensing slit (16) the fibre strand (3) is guided in a sliding manner, characterized in that the condensing slit (16; 516; 716; 1016) has a base (17; 517) which is convexly shaped in transport direction (A) and in that the base (17, 517) is continued at the end of the condensing slit (16; 516) by a similarly convexly shaped fibre guiding surface (181; 518; 718; 1018) of the condensing element (15;515). 2. An arrangement as claimed in claim 1, wherein the base (17) is V-shaped in cross section. 3. An arrangement as claimed in claim 1, wsherein the fibre strand (3) is guided along a part of the periphery (19; 519) of a delivery roller (6; 11; 12) of the delivery roller pair (6; 7; 11, 12), before it reaches the nipping line (13; 10). 4. An arrangement as claimed in claim 3, wherein the fibre guiding surface (18; 518) is pressed against the delivery roller (6; 11; 12). 5. An arrangement as claimed in claim 4, wherein a convexly shaped intake guiding surface (21; 521) of the condensing element (15; 515) preceeds the slit base (17; 517) at the start of the condensing slit (16;516), which in take guiding surface (21; 521) is pressed against a nipping roller (6; 7) of a nipping roller pair (6, 7) arranged upstream of the condensing element (15;515). 6. An arrangement as claimed in claim 4 or 5, wherein the fibre guiding surface (18) and/or the intake guiding surface (21) can be pressed onto the relevant delivery roller (12) or nipping roller (7) by means of a preferably adjustable loading spring (23). 7. An arrangement as claimed in claims 1 to 6, wherein the condensing slit (16) is formed by lateral nibs (24, 25). 8. An arrangement as claimed in claims 1 to 7, wherein the length of the slit base (17; 915) comprising that of a fibre guiding surface (18; 518) and an intake guiding surface (21; 521), corresponds to the average fibre length of the fibre strand (3). 9. An arrangement as claimed in claims 1 to 8. wherein the condensing element (15; 515) is arranged downstream of the drafting area of a drafting unit (4). 10. An arrangement as claimed in claims 1 to 8, wherein the condensing element is arranged in the last drafting zone (727) of a drafting unit. 11. An arrangement as claimed in claims 1 to 10, wherein the condensing element (15), together with further condensing elements, are arranged on a guide rail (26) which extends along a number of spinning positions. 12. An arrangement as claimed in claims 1 to 11, wherein the condensing element is mounted on a top weighting arm of a drafting unit. The invention relates to an arrangement (1) for mechanical condensing of a fibre strand (3) comprising a condensing zone (2) which is arranged downstream of a drafting unit (4) being bordered by a nipping line (13); and a condensing element (15) disposed upstream of the nipping line (13) formed of a delivery roller pair (11, 12), the condensing element (15) having a groove-like condensing slit (16) which tapers laterally in transport direction A, on the base (17) of said condensing slit (16) the fibre strand (3) is guided in a sliding manner, characterized in that the condensing slit (16; 516; 716; 1016) has a base (17; 517; 717; 1017) which is convexly shaped in transport direction (A) and in that the base (17; 517; 717; 1017) is continued at the end of the condensing slit (16; 516; 716; 1016) by a similarly convexly shaped fibre guiding surface (18; 518; 718; 1018) of the condensing element (15; 515; 715; 1015).

Documents:

407-kolnp-2006-granted-abstract.pdf

407-kolnp-2006-granted-claims.pdf

407-kolnp-2006-granted-correspondence.pdf

407-kolnp-2006-granted-description (complete).pdf

407-kolnp-2006-granted-drawings.pdf

407-kolnp-2006-granted-examination report.pdf

407-kolnp-2006-granted-form 1.pdf

407-kolnp-2006-granted-form 18.pdf

407-kolnp-2006-granted-form 2.pdf

407-kolnp-2006-granted-form 26.pdf

407-kolnp-2006-granted-form 3.pdf

407-kolnp-2006-granted-form 5.pdf

407-kolnp-2006-granted-letter patent.pdf

407-kolnp-2006-granted-reply to examination report.pdf

407-kolnp-2006-granted-specification.pdf