Title of Invention

SPINNING MACHINE

Abstract

57) Abstract:- This invention relates to a spinning machine comprising at least one multistage drafting system, fed from a roving frame bobbin or a sliver can, whereby a suction roller is connected to the system which forms a guide for the sliver on its circumference for the purpose of forming a condensing stage in which the already finally drafted but not yet twisted sliver is condensed or bunched to form a compact fibre strand in particular, of not more than 1.5mm wide and preferably less than 1mm wide, and a connecting spinning device which gives the spinning twist to the compact fibre strand emerging from the twist inhibiting nip, there being formed radially immediately inside the inner surface of the suction roller a suction zone, defined by an opening in a screen which has at least one boundary aligned obliquely relative to the circumferential direction of the suction roller. PRICE: THIRTY RUPEES

Full Text

stion roller on the drafting system Description The invention concerns a spinning machine, particularly a ring spinning machine according to the pre-characterizing clause of Claim 1. 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. This invention can also be used particularly advantageously in the ring spinning method and ring spinning machine according to the currently filed patent application titled "Ring spinning method and ring spinning machine" (Patent Application reference R 3297), where the blown air current is replaced by appropriate air ducting means. In respect of the content of this parallel application, therefore, reference is also made to that of the present application. The aerodynamic compression of the fibres, which follows the high-draft, produces a compact fibre strand oif about 1 mm in width which also forms the basis 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 turning of the sliver. 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 output 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 numbers. IVlechanical 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 32 919 A1; 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 yarn. 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. In order to reduce the wear within the multiple drafting system, the latter generally possesses a traversing device which causes the sliver entering the multiple drafting system over a width of about 6 to 10 mm to be traversed at intervals of time, in the order of magnitude of 1 min. In such cases, however, problems are encountered in the use of a suction zone formed as an oblique slit, the latter having the fundamental advantage that the sliver is bunched both aerodynamically and mechanically on the front edge of the oblique slit, as viewed in the direction of delivery. The traversing process changes the timing of the action of the oblique slit due to the fact that the sliver moves for a relatively long time along the front edge. The object of the present invention is to create a ring spinning machine of the type stated at the start of the document which allows perfect combined aerodynamic and mechanical bunching of the sliver within the draft-free condensing zone both with the use of a traversing device and without such a traversing device preceding the multiple drafting system. To achieve this object, there is proposed a spinning machine having the characteristics of Claim 1. Advantageous further developments of the invention are identified by the Sub-Claims. The concept of the invention, therefore, is that the suction zone, which is delimited axially and preferably also rectilinearly against the direction of rotation of the suction roller, extends in the area of this delimitation over a length which is somewhat greater than the length of the traversing movement and tapers, essentially symmetrically, in the direction of feed of the sliver. In this way, during the traversing movement the sliver comes into contact alternately with the left or right opposing oblique boundary of the suction zone so that, in spite of the traversing movement, there is achieved a perfect, combined aerodynamic and mechanical bunching of the sliver to form a compact fibre strand. By contrast with an oblique slit with edges disposed parallel to each other in which a superimposed traversing movement substantially changes the path ratios of the sliver, this is reduced by the design of the suction zone according to the invention, particularly its triangular and symmetrical design. The narrow discharging point at the end of the suction zone in the direction of feed is particularly important for the attainment of particularly good bunching of the sliver. The design of the suction zone according to the invention, which is at least essentially triangular, can be combined with a substantial reduction of the total surface area of the suction zone, in that the triangle is substantially shortened in the direction of feed and the second half of the suction zone, viewed in the circumferential direction, is formed as only a narrow slit extending circumferentially. Accordingly the present invention provides a spinning machine comprising at least one multi-stage drafting system, fed from a roving frame bobbin or a sliver can, whereby a suction roller is connected to the system which forms a guide for the sliver on its circumference for the purpose of forming a condensing stage in which the already finally drafted but not yet twisted sliver is condensed or bunched to form a compact fibre strand in particular, of not more than 1.5 mm wide and preferably less than 1 mm wide, and a connecting spinning device which gives the spinning twist to the compact fibre strand emerging from the twist inhibiting nip, there being formed radially immediately inside the inner surface of the suction roller a suction zone, defined by an opening in a screen which has at least one boundary aligned obliquely relative to the circumferential direction of the suction roller. With reference to the accompanying drawings, in which; invention is described using examples with reference the 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. Fig. 3 shows a greatly enlarged schematic sectional view along line Ill-Ill of Fig. 1 with a first embodiment of the suction air ducting means. Fig. 4 shows a greatly enlarged section along line Ill-Ill of Fig. 1 with a further embodiment of the air ducting means according to the invention. Fig. 5 shows, in schematic form, a radial top view of a first advantageous embodiment of a suction zone according to the invention. Fig. 6 shows a further advantageous embodiment of the suction zone according to the invention. Fig. 7 shows a particularly advantageous form of the suction zone according to the invention for reduction of the volume of suction air required. Fig. 8 shows a sectional view, analogous to Fig. 3, but in the area of the rectilinear slit piece according to Fig. 6 or 7. Figs. 1 and 2 show 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 intake 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 output 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 output 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. 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 fibre strand 22 is constantly in contact with the perforation 35. Within the suction roller 25 there is a concentric screen 32, interrupted 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. The drafting system 13 preferably 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. Figs. 1, 2 and 3 show that the suction zone 33 in the form of an opening within the screen 32 is delimited not only circumferentially to the length of the guide piece 15 but also widthwise to a width d which lies within the same order of magnitude as the width of the perforation area 35. According to the invention and as shown by Figs. 1 to 3, there is a deflection screen 40, disposed radially outside the suction roller 25 above the suction zone 33, which extends in the circumferential direction essentially over the guide piece 15 between the rollers 26, 27 and, in the axial direction, extends on both sides beyond the width d of the suction zone 33. The distance A of the deflection screen 40 from the outside surface of the suction roller 25 is approximately equal to the width d of the suction zone 33. Due to the fact that the deflection screen 40 extends laterally beyond the suction zone 33 by a significant amount the air current 34 sucked in from the outside is forced to flow from both sides in an essentially axial direction to the fibre strand 22, located approximately in the centre of the suction zone 33, where it impinges on the fibre strand 22 on all sides and essentially from both axial sides. This results in a great axial compression of the fibre strand, producing an extremely good bunching of the fibres to form a compact fibre strand 22 of substantially less than 1 mm wide. Following the high-drafts, effected essentially within the main draft zone 24, there is thus achieved without drafting and without a blown air current in the condensing area (guide piece 15), between the nips 14, 16 formed between the rollers 26, 27 and the suction roller 25, 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. In the embodiment example shown in Fig. 4 the deflection screen 40', likewise disposed concentrically relative to the suction roller 25, has an opening 42 on one side only through which the air 34 can flow in an essentially axial direction to the suction zone 33. On its other side, the deflection screen 40' has a wall 31, projecting radially inwards, which is essentially flush with the lateral boundary of the suction zone 33 located on this side of the deflection screen 40'. This design causes the air current 34, which acts in an essentially axial and partially radial direction on the sliver 22, to press the sliver simultaneously against the wall 31 and the perforation 35 so that it is compressed between the air current 34 and the wall 31, being thereby bunched to form a very narrow compact fibre strand of less than 1 mm wide. Since a ring spinning machine normally has numerous spinning units, as shown in Figs. 1 to 4, arranged adjacently, the deflection screen 40' can also extend from the opening 42 to an adjacent suction zone where there is a wall, laterally reversed relative to the wall 31, in alignment with one opposing edge of the suction zone. Sufficiently large circumferential openings must then be provided on the ends of the deflection screen 40' or in the deflection screen 40' itself to allow the inlet of air from the outside. The essential invention concept of the embodiments according to Figs. 3 and 4, therefore, is that there is formed around the suction roller 25, in the area of the suction zone 33 or the guide piece 15 between the deflection screen 40, 40' and the outside surface of the suction roller 25, a partial annular gap 41 into which air can flow, essentially in the axial direction and essentially from only one or both sides. Normally, a ring spinning machine has 400 to 500 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 areas 35 each of which is equipped with a deflection screen 40, 40' as shown by Figs. 3 and 4. Figs. 5 to 7 show radial views of different embodiments of the suction zone 33 according to the invention, essentially in the direction of the arrows 34 of Fig. 1. The reference F denotes the direction of feed of the sliver. As shown by Fig. 5, the suction zone 33 has the form of an acute isosceles triangle with a symmetry axis 43 running in the circumferential direction of the suction roller 25 and dividing the suction zone 33 into two equal, laterally reversed halves. The leading boundary of the suction zone 33 is constituted by a rectilinear base 33' running perpendicularly to the symmetry axis 43, or parallel to the indicated rotational axis 36 of the suction roller 25. The sliver entering the suction zone 33 from the top of Fig. 5 across the base 33' is traversed, for example, within the area B which is somewhat shorter overall than the base 33' but lies entirely within the latter. By this means, during transfer over the suction zone 33 on the suction roller 25 the sliver alternately reaches both the right-hand boundary 33" and the left-hand boundary 33"' of the suction zone 33 (as viewed in the direction of feed), so that there is a combined aerodynamic and mechanical bunching of the sliver with the sliver path ratios remaining largely unchanged. The boundaries 33" and 33'" of the suction zone 33 run obliquely in opposite directions towards the tip 33"" of the triangular suction zone 33. The length of the suction zone 33 in the circumferential direction is between 25 and 40 mm from the axial base 33' to the tip 33"". Likewise, in the embodiment example shown in Fig. 6, in which the same reference numbers are used to denote the corresponding elements in the preceding figures, the suction zone 33 is initially triangular. In this case, however, the lateral boundaries 33" and 33'" form a wider angle with the symmetry axis 43 so that the height of the triangle is significantly shorter than that of the triangle in Fig. 5. Adjoining the tip 33"" of the triangle in Fig. 5 in the circumferential direction is a rectilinear slit piece 45, having a width of 1 to 2 mm, extending in the direcfion of feed F. . In this way, likewise, a traversing excursion B of the sliver is achieved within the condensing zone with combined aerodynamic and mechanical bunching at the lateral boundaries 33" and 33'". This bunching during transfer within the rectilinear slit piece 45 maintains and further promotes the previous bunching of the compact fibre strand 22. In the embodiment example of the suction zone 33 according to Fig. 7, the rectilinear and axial base 33' of the suction zone 33 is adjoined by concave lateral boundaries 44, laterally reversed relative to the symmetry axis 45, which transform in the direction of feed into a rectilinear slit piece 45 having a width of 1 to 2 mm. As shown by Fig. 8, located symmetrically over the approximately 1 to 2 mm wide rectilinear slit piece 45 there is a row of holes 35 of the suction roller 25 having a hole diameter of, preferably, 0.8 mm. Lilkewise, on the concave, tapering lateral boundaries 44 there is an optimum combined aerodynamic and mechanical bunching of a sliver moved forwards and backwards within the traversing excursion B. Following compacting the sliver then runs, under the action of the suction air flow, into the narrow rectilinear slit piece 45, which points in the circumferential direction, where the bunching is maintained and further promoted. The advantage of the form with the concave lateral boundaries 44 as shown in Fig. 7 is that the total surface area of the suction zone 33 responsible for the total volume of suction air is further reduced by comparison with the two other forms without impairment of the bunching effect while perfect sliver path ratios are maintained. WE CLAIM : 1. A spinning machine comprising at least one multi-stage drafting system (13), fed from a roving frame bobbin (12) or a sliver can, whereby a suction roller (25) is connected to the system which fonns a guide for the sliver (22) on its circumference for the purpose of forming a condensing stage (25, 26, 27) in which the already finally drafted but not yet twisted sliver is condensed or bunched to form a compact fibre strand (22) in particular of not more than 1.5mm wide and preferably less than 1mm wide, and a connecting spinning device (17) which gives the spinning twist to the compact fibre strand (22) emerging from the twist inhibiting nip (16), there being formed radially immediately inside the inner surface of the suction roller (25) a suction zone (33), defined by an opening in a screen (32) which has at least one boundary aligned obliquely relative to the circumferential direction of the suction roller (25). 2. The spinning machine as claimed in claim 1 wherein the end of the suction zone (33) opposing the direction of rotation of the suction roller (25) has a width of 8 to 12 mm and tapers in the direction of feed of the sliver. 3. The spinning machine as claimed in claim 1 wherein, preceding the multiple drafting system (13), a traversing device (42) is provided, and the end of the suction zone (33) opposing the direction of rotation of the suction roller (25) has a width greater than that of the traversing excursion (B) and tapers in the direction of feed of the sliver. 4. the spinning machine according to claim 1, wherein the said zone (33) has a symmetry axis (43) running in the circumferential direction of the suction roller (25). 5. The spinning machine according to any one of the claims 1 to 4, wherein the said suction zone (33) has the form of a funnel with walls (44) which run towards each other being disposed, in particular, symmetrically relative to each other and possesses a narrow slit piece (45), adjoining in the direction of feed of the sliver, which is preferably rectilinear and extends in the circumferential direction of the suction roller (25). 6. The spinning machine according to any one of the preceding claims, wherein the total length of the said suction zone (33) in the circumferential direction is 25 to 40 mm. 7- The spinning machine according to any one of the claims 5 or 6, wherein the said rectilinear slit piece (45) in the circumferential direction Is approximately half that of the total suction zone. 8. The spinning machine according to any one of claims 5 to 7, wherein the width of the said rectilinear slit piece is 1 to 2 mm. 9. The spinning machine according to claim 8, wherein above the said rectilinear slit piece (45) a row of holes (35) preferably of 0.8 mm diameter. 10. The spinning machine according to any one of the preceding claims, wherein the said suction roller (25) forms the delivery roller of the drafting system (13). 11. The spinning machine according to any one of the preceding claims, wherein the said suction roller (25) bears on both the counter drafting system delivery roller (26) and a twist inhibiting counter roller (27) which is offset at an angle around the guide piece (15). 12. The spinning machine according to any one of the preceding claims, wherein the said suction roller (25) and the twist inhibiting counter roller (27) are positioned to form a twist inhibiting nip (16) in between them. 13. A spinning machine, substantially as herein described with reference to the accompanying drawings.

Documents:

478-mas-95 abstract.pdf

478-mas-95 claims.pdf

478-mas-95 correspondence-others.pdf

478-mas-95 correspondence-po.pdf

478-mas-95 description (complete).pdf

478-mas-95 drawings.pdf

478-mas-95 form-1.pdf

478-mas-95 form-26.pdf

478-mas-95 form-4.pdf

478-mas-95 others document.pdf