Title of Invention

A RING SPINNING MACHINE

Abstract

A ring spinning machine comprising atleast one multi-stage drafting system (13) fed from a roving bobbin (12); a connecting draft-free condensing stage (25,26,27) for condensing the already finally drafted but not yet twisted fibre band; a compact fibre strand (22) of not more than 1.5mm wide, preferably less than 1 mm wide; a twist inhibiting nip (16), terminating the condensing stage (25,26,27), between two rollers (25,27) and a connected ring spinning device (17) for twisting and winding the compact fibre strand (22) emerging from the twist inhibiting nip (16), wherein the drafting system (13) has a total draft of 60 to 150-fold, in particular 60 to 120-fold.

Full Text

Ring spinning method and ring spinning macliine Description The invention concerns a ring spinning method according to the pre-characterizing clause of Ciaim 1 and a ring spinning machine according to the pre-characterizing clause of Claim 10. In a known ring spinning method and a known ring spinning machine of this type (DE 39 27 936 A1; textile praxis international 1993, September, Pages 684-686), one or two parallel rovings are each guided to one half of a ring spinning drafting system where they are drawn, with standard draft values, and then delivered without further drafting to the aerodynamic fibre compression system on a perforated suction roller. In the known method, therefore, there is an aerodynamically compact compression of the sliver on the surface of the perforated suction roller or drum, with a positive effect being achieved by separation of the processes of drafting and condensing the fibres. For the purpose of compression, the already drawn sliver, which is held on the surface of the suction drum by a current of suction air, is deflected in the direction of its axis so that, within the sliver, the fibres are drawn in a parallel alignment and bunched together as a result of juxtaposing the individual fibres by means of a transverse movement. In general, the process initiated by the suction action is promoted by the action of a blown air current impinging on the surface so that, during transfer to the nip line for the turning process, the separate fibres are held in a stable equilibrium between the applied air currents. The aerodynamic compression of the fibres, which follows the high-draft, produces a compact fibre strand of about 1 mm in width or less which also forms the base of the spinning triangle following the twist inhibiting nip. The height of the spinning triangle is thus reduced accordingly. The aerodynamic bunching of the fibres can thus affect the twisting of the sliver. The invention, however, also concerns a mechanical condensing process which occurs not at the end of the high-draft zone of the drafting system - as is frequently the case - but only on the draft-free guide piece to the twist inhibiting nip, following the high-draft zone. Ring spinning machines normally use three-cylinder drafting systems, the middle pair of cylinders located at the start of the high-draft zone being generally equipped with double aprons which extend to a point close to the intake nip of the pair of delivery rollers. Depending on the fineness of the yarn, three-cylinder drafting systems fed with a roving have drafts of 25 to 50-fold, the higher drafts corresponding to finer yarn counts. Mechanical condensers have also previously been used between the ends of the aprons in the main draft zone and the nip between the output cylinders of the drafting system for the purpose of bunching the sliver (DE 41 32 919A1; DE 41 41 237 A1). The improvement in yarn quality attainable by this means is limited, however, since the friction of the individual fibres on the condenser guide elements results in irregularities in the yam. For this reason condensers located at the end of the main draft zone do no yet constitute an optimum means for significantly improving yarn quality. However, by bunching the sliver in the high-draft zone before its entry into the delivery nip of the drafting system, it is possible to increase the total draft of the drafting system to values approaching 60-fold, without the base of the spinning triangle assuming unacceptably high values. Even in such a high-efficiency drafting system higher drafts would impair the yam quality. The invention is therefore based on the known compact spinning process but also comprises other types of sliver condensing or compacting systems after the main draft zone in the draft-free area to the twist inhibiting nip. The object of the invention is to create a ring spinning method and a ring spinning machine of the type mentioned at the start of the document by means of which both the efficiency and yarn quality can be substantially increased. To achieve this object, the features contained in the characterizing part of Claims 1 and 10 are proposed. Advantageous further developments are given by Claims 2 to 6 and 11 to 13. While the total drafts of conventional ring spinning drafting systems were limited to a maximum value of 60-fold due to the fact that sensitive quality losses are to be anticipated at higher drafts, the draft range according to the invention commences above the value of 60 hitherto considered as the outer limit and ranges to a value of 120-fold, the draft range of 80 to 100-fold representing an optimum in respect of the yam quality achieved. The invention is based on the knowledge that the otherwise negative effect of higher drafts is eliminated by the known exceptional condensing of the fibre between the outlet from the main draft zone and the twist inhibiting nip, while the effect of the improvement in intemai sliver guidance at higher drafts is maintained, so that the higher draft values according to the invention not only improve the efficiency but also, surprisingly, substantially improve the quality of the yarn produced. An unexpected and disproportionate improvement is thus achieved by the measure according to the invention. The method according to the invention and the ring spinning machine according to the invention can be applied in the processing of rovings of combed cotton, man-made fibres and fibre mixtures. Claims 7 to 9 specify preferred areas of application of the method according to the invention, while Claims 16 and 17 define preferred embodiments of the ring spinning machine according to the invention. Accordingly the present invention provides a ring spinning machine comprising atleast one multi-stage drafting system fed from a roving bobbin a connecting draft-free condensing stage for condensing the already finally drafted but not yet twisted fibre band; a compact fibre strand of not more than 1 5 mm wide, preferably less than 1 mm wide; a twist inhibiting nip terminating the condensing stage between two rollers and a connected nng spinning device for twisting and winding the compact fibre strand emerging from the twist inhibiting nip wherein the drafting system has a total draft of 60 to 1.50-fold, in particular 60 to 120-fold. The invention is described below using examples and with reference to the accompanying drawing. Fig. 1 shows a schematic side view of a single spinning unit of a ring spinning machine according to the invention. Fig. 2 shows a front view of the same spinning unit. The drawing shows a roving 11 being fed from an upper roving frame bobbin 12 via a deflection element 28 into a three-cylinder drafting system 13 with a pre-draft zone 23, possessing a pair of feed rollers 37, 37', and a main draft zone 24. The pair of rollers 29, 29' at the end of the pre-draft zone 23 and at the beginning of the main draft zone 24 are equipped, in the known manner, with aprons 30, 30', indicated in schematic form only, which extend into the draw-in nip of a pair of delivery rollers 25, 26. The lower roller of the pair of delivery rollers is constructed as a perforated suction roller 25, having a substantially larger diameter than the other rollers and a rotational axis 36, which together with a counter drafting system delivery roller 26 forms the last nip clearance 14 of the drafting system 13. Following the delivery nip 14, the sliver passing through the drafting system 13 is guided along a curved guide piece 15 over a part of the circumference of the suction roller 25 to a twist inhibiting counter roller 27 which, together with the suction roller 25, forms a twist inhibiting nip 16 for the sliver. Air can also be blown, through a blowing pipe 31 above the guide piece 15, on to or near the sliver passing over the guide piece 15. As shown by Fig. 2, the perforation 35 of the suction roller 25 extends over its entire circumference, but only over a small width of the circumferential wall of the suction roller 25, this being nevertheless of such a width, even allowing for any traversing motion of the fibre strand 22, that the strand 22 is constantly in contact with the perforation 35. Within the suction roller 25 there is a fibre concentric screen 32, open in the area of the guide piece 15, which Is disposed so that an air current, flowing radially from the outside inwards, is produced as a result of a negative pressure maintained within the screen 32, passing through the perforation 35 of the suction roller 25 in the direction of the arrows 34. After the twist inhibiting nip 16, the sliver is passed by twist distribution into a conventional ring spinning device 17 which is equipped with a ring rail 18, ring 19, traveller 20, spindle rail 38 and spindle 21 and produces the ring spun yarn 39 from the compact fibre strand 22 emerging from the twist inhibiting nip 16. According to the invention, the drafting system 13 effects a total draft of 80 to 100-fold, the draft within the pre-draft zone 23 being only within the normal limits of 1.1 to 1.3-fold. Following the high-drafts, effected essentially within the main draft zone 24, there is thus achieved without drafting in the condensing area (guide piece 15), between the nips 14,16 of the rollers 26, 27, such bunching of the fibre strand 22 that an exceptionally high yarn quality is obtained after the discharge nip 16; the condensing according to the invention not only eliminates the effect of the main draft zone widening the sliver but also over-compensates this by a significant improvement in the yarn quality. Normally, a ring spinning machine has 100 to 200 adjacent spinning units, as described above. Generally, one loading arm is assigned to four adjacent draft zones. Furthermore, a suction roller 25 can be assigned to one loading arm so that, in practice, the suction roller 25 has four adjacently spaced perforation zones 35. We Claim 1.A ring spinning machine comprising atleast one multi-stago drafting system (13) fed from a roving bobbin (12); a connecting draft-free eondensing stage (25, 26, 27) for condensing the already fmally drafted but not yet twisted fibre band; a compact fibre strand (22) of not more than 1.5 mm wide, preferably less than 1 mm wide; a twist inhibiting nip (16), terminating the condensing stage (25. 26, 27), between two rollers (25, 27) and a connected rmg spinning device (17) for twisting and winding die compact fibre strand (22) emergmg from the twist inhibiting nip (16) wherein the drafting system (13) has a total draft of 60 to 150-fold, in particular 60 to 120-fold. 2. The ring spinning machine according to Claim 1 wherein the drafting system (13) has a total draft greater than 65-fold and less than 150 fold. 3. The ring spinning machine according to Claim 2, wherein the drafting system (13) has a total draft of 70 to llO-foM. 4. Ring spmning machine accordmg to Calfan 3, wherein die drafting system (13) has a total draft of 80 to 100-fold. 5. Ring spinning machine according to any one of Claims 1 to 4, wherein the said multi-stage draftimg system (13) has a pre-draft zone (23) and amain draft zone (24). 6. The ring spinning machine according to Claim 5, wherein aprons (30) are disposed on the rollers (29, 29) at the entrance (30) of the main draft zone (24). 7. The ring spinning machine according to any one of the Claims 2 to 6 wherein the pre-draft zone (23) of the drafting system (13) has a draft withm the conventional range of, in particular, 1.1 to 1.3-fold. 8. The ring spinning machine according to any one of Claimsl to 7 wherein one delivery roller of the drafting system (13) is a suction roller (25) and a twist inhibitmg counter roller (27) with a twist inhibitmg nip (16) is disposed, offset from the counter draftmg system delivery roller (26) at an angle, relative to the suction roller, around the guide piece (15) in the sliver feed direction. 9. Ring spinning machine substantially as herein described with reference to the accompanying drawings.

Documents:

479-mas-95 abstract.jpg

479-mas-95 abstract.pdf

479-mas-95 claims.pdf

479-mas-95 correspondence-others.pdf

479-mas-95 correspondence-po.pdf

479-mas-95 description (complete).pdf

479-mas-95 drawings.pdf

479-mas-95 form-1.pdf

479-mas-95 form-26.pdf

479-mas-95 form-4.pdf

479-mas-95 others document.pdf