Title of Invention

AN ARRANGEMENT FOR CONDENSING A DRAFTED FIBRE STAND

Abstract

A condensing zone (15) is arranged downstream of the front roller pair (8) of a drafting arrangement (1) of a spinning machine, in which condensing zone a drafted roving or a silver is condensed. The condensing zone comprises af suction device (16), which has a closed hollow profile (17), which serves as a sliding surface for a circulating sieve belt (20, 29). The sieve belt transports the drafted fibre strand (10) to a nipping roller (25), which presses the fibre strand and the sieve belt against the sliding surface at a nipping point (26, 27). The fibre strand travels over an essentially in transport direction extending suction slit (21, 22; 39, 40; 41, 42) located in the condensing zone, which suction slit extends to the nipping point.

Full Text

BACKGROUND AND SUMMARY OF THE INVENTION An arrangement for condensing a fibre strand drafted in a drafting apparatus of a ring- spinning machine. The present invention relates to an arrangement for condensing a drafted fibre strand in a condensing zone arranged downstream of a front roller pair of a drafting arrangement, which condensing zone comprises a stationary sliding surface having at least one essentially in transport direction extending suction slit and a perforated transport belt which transports the fibre strand over the sliding surface, to which transport belt a nipping roller, defining the delivery side of the condensing zone, is arranged. An arrangement of this type is prior art in Indian patent 185 284. The drafting of the sliver or the roving ends at the front roller pair. A condensing zone is located between the front roller pair and a delivery roller pair arranged downstream thereof, in which condensing zone the drafted fibre strand is condensed transversely to the transport direction, so that when exiting the delivery roller pair, a spinning triangle does not arise when the fibre strand is subsequently twisted to a yarn. The perforation corresponds to the width to which the fibre strand is to be condensed. A belt cradle effects the guidance of the belt, which cradle takes the form of a suction device and comprises a sliding surface. As a result of a delivery roller pair being arranged downstream of the suction device, the suction of the fibre strand ends at a clear distance from the nipping point of the delivery roller pair. The condensed fibre strand can, disadvantageously, spread out again before it reaches the nipping point. Thus the actual aim of the condensing zone is only partly achieved. It is an object of the present invention to arrange the condensing zone downstream of the front roller pair of the drafting arrangement in such a way that the condensed fibre strand retains its condensed state until it reaches the nipping point. This object has been achieved in accordance with the present invention in that the nipping roller presses the transport belt to a nipping point on the sliding surface and that the suction slit extends to the nipping point. As the nipping roller does not operate in conjunction with another delivery roller, but rather with a stationary sliding surface, the suction can be applied up to the nipping point. The width of the condensing effect is not determined by the perforation of the transport belt, but rather by the width of the suction slit applied in the sliding surface, which suction slit extends up to the nipping point defined by the nipping roller. An advantage is attained in that the pneumatically generated condensing of the fibre strand is maintained also at the nipping point, so that subsequently a fibre strand, still in a condensed state, can be twisted into a yarn. The result is a yarn with a good material utilization and high tensile strength which is less hairy. The condensing effect can be increased when the suction slit is designed tapering in transport direction of the fibre strand and/or when the suction slit extends diagonally to the direction of motion of the transport belt. In the latter case, the fibre strand obtains a slight false twist, by means of which, together with the friction effect of the transport belt, the outer fibres can be better wrapped around the fibre strand. A similar effect can be achieved when the transport belt tra- verses transversely to its direction of motion. The transport belt can have various designs. Advantageous is, however, a narrow-mesh woven band, which surrounds a sliding surface in the form of a hollow profile. It is hereby favourable when the hollow profile, serving as a sliding surface for the transport belt, is curved in transport direction. In addtion to the suction by the suction slit, this results in the fibre strand finding good support on the sliding surface. The hollow profile, in the form of a suction device, extends over a plurality of adjacent spinning stations, whereby as a result one suction device comprises a plurality of suction slits. The speeds of the nipping roller and the transport belt should be only slightly higher than the speed of the front roller pair, namely by such an amount that a certain necessary tension is effected on the fibre strand. Further drafting is not necessary. In order to achieve this, the nipping roller is driven by a roller of the front roller pair of the drafting arrangement and drives for its part the transport belt. The nipping roller can be arranged together with the top roller of the front roller pair to a joint rocker, which is in turn arranged to the top weighting arm of the drafting arrangement. The suction slit should be wider than the completed condensed fibre strand, for example 1.5 mm. The perforated area of the transport belt, in contrast, is significantly wider than the suction slit. BRIEF DESCRIPTION OF THE DRAWINGS These and further obects, 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 cut side view of a drafting arrangement comprising a condensing zone according to the present invention; Figure 2 is a view in the direction of the arrow II of Figure 1 of the sliding surface and two transport belts; Figure 3 is a view similar to Figure 1 with a belt drive for the nipping roller; Figure 4 is a view from above in the direction of the arrow IV of Figure 3 onto the condensing zone; Figure 5 is a part view similar to Figure 1, whereby the top roller of the front roller pair and the nipping roller are arranged to a rocker; Figure 6 is a view similar to Figure 2, whereby the suction slits extend diagonally to the direction of motion of the transport belts, Figure 7 is a view similar to Figure 2, whereby the transport belts traverse transversely to their direction of motion. DETAILED DESCRIPTION OF THE DRAWINGS The arrangement according to Figures 1 and 2 shows a drafting arrangement 1, which comprises three driven bottom rollers 2,3 and 4, which are arranged in a known way on continuous drive shafts arranged in machine longitudinal direction. Upper rollers 5,6 and 7, in the form of pressure rollers, are arranged to the bottom rollers 2,3 and 4. The bottom roller 4 and the top roller 7 form together the front roller pair 8 of the drafting arrangement 1, on which the roving or sliver 9 delivered in direction A undergoes a complete drafting process. Downstream of the front roller pair 8 therefore, a drafted fibre strand 10 is present, which undergoes a subsequent treatment downstream of the drafting arrangement 1, before it is delivered in delivery direction B to a twisting device, for example a ring spindle, and twisted to a yarn 11. The middle bottom roller 3, as well as the middle top roller 6 are provided with a lower belt 12 or an upper belt 13. In addition reference is made to a guiding table 14 for the lower belt 12. A condensing zone 15 is arranged downstream of the drafting arrangement 1, which serves the purpose of condensing the drafted fibre strand 10 in such a way that remaining outer fibres still extending out from the fibre strand 10 are disposed on the core of the fibre strand 10. This increases the material utilization and the tensile strength of the yarn 11 to be spun, while reducing hairiness. A suction device 16 is arranged to the condensing zone 15, which suction device 16 comprises a closed hollow profile 17. The hollow profile 17 extends, as can be seen in particular in Figure 2, advantageously over two adjacent spinning stations 18 and 19, whose gauge distance to one another is denoted by c. The hollow profile 17 consists of plastic or stainless steel or of any other low-friction coated material. It serves as a sliding surface for two transport belts 20 and 29, which slide thereon, of which each is respectively arranged to a spinning station 18,19. The transport belts 20, 29 are endless and perforated and can take the form of a latticed belt or sieve foil or advantageously as a narrow-meshed woven band. They surround the hollow profile 17 and cover the suction slits 21,22, which are arranged at a gauge distance c from one another. The transport belts 20 and 29 transport the drafted fibre strand 10 to a nipping point 26 or 27, which is formed in that a nipping roller 25 presses the respective transport belt 20 or 29 against the hollow profile 17. The suction slits 21 and 22 extend in transport direction A and are arranged on the side of the relevant transport belt 20,29 which faces away from the fibre strand 10. The suction slits 21 and 22 are sufficiently long to reach the nipping point 26 or 27. The suction device 16 is provided with a suction air connection 23, which is located approximately in the centre between the two spinning stations 18 and 19. The hollow profile 17 can, as shown in Figure 1, be additionally provided with a tension element 24 made of plastic, the purpose of which is the tension and guiding of the transport belt 20,29. The nipping roller 25 drives the respective transport belt 20 or 29 and presses it against the hollow profile 17 of the suction device 16. The nipping roller 25 is driven by the top roller 7 of the front roller pair 8 by means of a transfer roller 28, namely at a circumferential speed which only slightly exceeds the circumferential speed of the front roller pair 8. The embodiment according to Figures 3 and 4 differs essentially from the embodiment described above only in that the nipping roller 25 is now driven by means of a transfer belt 30 by the top roller 7 of the front roller pair 8. It is superfluous to describe the above mentioned components again. As can be seen from Figure 4, the top roller 7, as well as the other top rollers 5 and 6, and the nipping roller 25 are each provided with a flexible covering 31 or 32, so that the respective drives can be transferred by means of friction and thus that a flexible pressing is achieved. The axles 33 and 34 of the top roller 7 and the nipping roller 25 can be seen in Figure 4, which axles are both joined together with the top roller and the nipping roller of the adjacent spinning station to form a twin top roller. During transport of the drafted fibre strand 10 by means of the very thin woven-like transport belt 20 or 29, the suction slits 21 and 22 suck the fibre strand 10 and guide the outer fibres together, whereby the fibre strand 10 is condensed. As the suction slits 21 and 22 reach to the nipping point 26 or 27, the condensed state of the fibre strand 10, in contrast to the prior art described above, remains constant up until the twist is applied. In the following described embodiments, components which are described above are not repeated here. According to Figure 5, the top roller 7 of the front roller pair 8 and the nipping roller 25 of all embodiments can be arranged to a joint rocker 35. This can be swivelled around a swivel axle 36, by means of whose position the pressure load of the top roller 7 and the nipping roller 25 can be determined. The rocker 35 is supported by means of a load spring 37, which is in turn arranged to the top weighting arm 38 of the drafting arrangement 1. According to Figure 6, the suction slits 21 and 22 can be replaced by suction slits 39 and 40 in all embodiments, which suctions slits 39 and 40 extend inclined to the direction of motion of the transport belts 20 and 29. The respective fibre strand 10 thus receives a slight false twist in addition to its transport direction, as the fibre strand 10 follows the change in direction of the suction slits 39,40 and thereby rolls on the surface of the respective transport belt 20,29. This supports the winding of the outer fibres around the core of the fibre strand 10. Differing from Figure 6, the diagonal of the suction slits can also be identically aligned, or replaced by a lateral staggering of a plurality of suction slits extending in transport direction. The suction slits 41 and 42 shown in Figure 7 taper in transport direction of the fibre strand 10, a measure which can also be provided in the case of the suction slits 21, 22, 39 and 40 described above. Furthermore, the hollow profile 17 can be designed traversing according to the traverse directions C and D (in a way not shown here). Corresponding lateral guides 43 ensure that the transport belts 20 and 29 also make this lateral traversing motion. This measure, which can be applied to the embodiments described above, as a single measure or an additional one, ensures an additional rolling of the fibre strand 10, which thus results in an increased condensing. WE CLAIM; 1. An arrangement for condensing a fibre strand (10) drafted in a drafting apparatus of a ring-spinning machine , comprising: - a drafting arrangement (1) comprising a front roller pair (8), - a condensing zone (15) arranged downstream of said front roller pair (8), - a stationary sliding surface in the condensing zone (15), said sliding surface comprising at least one suction slit (21) extending essentially in transport direction of the fibre strand (10), - a perforated transport belt (20) which transports the fibre strand (10) over the sliding surface, - and a nipping roller (25) defining a nipping point (26) at a delivery side of the condensing zone (15), wherein the nipping roller (25) presses the transport belt (20, 29) to said nipping point (26, 27) on said sliding surface, and wherein the suction slit (21, 22; 39, 40; 41, 42) extends towards said nipping point (26, 27). 2. An arrangement as claimed in claim 1, wherein the said transport belt (20, 29) takes the form of a woven band. 3. An arrangement as claimed in claim 1 or 2, wherein the said sliding surface in the condensing zone (15) takes the form of a curved slideway. 4. An arrangement as claimed in any one of the claims 1 to 3, wherein the said condensing zone (15) comprises a suction device (16) containing a closed hollow profile (17), the outer contour of the hollow profile (17) taking the form of a sliding surface and being surrounded by the transport belt (20, 29). 5. An arrangement as claimed in claim 4, wherein the said hollow profile (17) is arranged jointly to a plurality of adjacent spinning stations (18, 19) and is therefore provided with a plurality of suction slits (21, 22; 39, 40; 41, 42). 6. An arrangement as claimed in any one of the claims 1 to 5, wherein the said transport belt (20, 29) is driven by the nipping roller (25). 7. An arrangement as claimed in any one of the claims 1 to 6, wherein the said nipping roller (25) is driven by a roller (7) of the front roller pair (8) of the drafting arrangement (1). 8. An arrangement as claimed in any one of the claims 1 to 7, wherein the said suction slit (41, 42) tapers in transport direction (B) of the fibre strand (10). 9. An arrangement as claimed in any one of the claims 1 to 8, wherein the said suction slit (39, 40) extends inclined to the direction of motion of the transport belt (20, 29). 10. An arrangement as claimed in any one of the claims 1 to 9, wherein the said transport belt (20, 29) traverses transversely to its direction of motion (traverse direction C-D). 11. An arrangement as claimed in any one of the claims 1 to 10, wherein the said top roller (7) of the front roller pair (8) and the nipping roller (25) are arranged to a joint spring-loaded rocker (35), which is arranged to a top weighting arm (38) of the drafting arrangement (1). 12. An arrangement as claimed in any one of the claims 1 to 11, wherein the said suction slit (21, 22; 39, 40; 41, 42) is wider than the condensed fibre strand (10). A condensing zone (15) is arranged downstream of the front roller pair (8) of a drafting arrangement (1) of a spinning machine, in which condensing zone a drafted roving or a silver is condensed. The condensing zone comprises af suction device (16), which has a closed hollow profile (17), which serves as a sliding surface for a circulating sieve belt (20, 29). The sieve belt transports the drafted fibre strand (10) to a nipping roller (25), which presses the fibre strand and the sieve belt against the sliding surface at a nipping point (26, 27). The fibre strand travels over an essentially in transport direction extending suction slit (21, 22; 39, 40; 41, 42) located in the condensing zone, which suction slit extends to the nipping point.

Documents:

17-CAL-1999-(27-12-2011)-CORRESPONDENCE.pdf

17-CAL-1999-FORM-27.pdf

17-cal-1999-granted-abstract.pdf

17-cal-1999-granted-claims.pdf

17-cal-1999-granted-correspondence.pdf

17-cal-1999-granted-description (complete).pdf

17-cal-1999-granted-drawings.pdf

17-cal-1999-granted-examination report.pdf

17-cal-1999-granted-form 1.pdf

17-cal-1999-granted-form 13.pdf

17-cal-1999-granted-form 2.pdf

17-cal-1999-granted-form 26.pdf

17-cal-1999-granted-form 3.pdf

17-cal-1999-granted-pa.pdf

17-cal-1999-granted-priority document.pdf

17-cal-1999-granted-reply to examination report.pdf

17-cal-1999-granted-specification.pdf

17-cal-1999-granted-translated copy of priority document.pdf