GB2158108A

GB2158108A - Pneumatically manufacturing fiber bundle yarn

Info

Publication number: GB2158108A
Application number: GB08506567A
Authority: GB
Inventors: Alois Stejskal; Miroslav Stepanek; Zdenek Havranek; Ladoslav Novak; Frantisek Ferkl; Eduard Barta; Frantisek Cada; Jaroslav Slinar; Zelmira Borovcova; Jirina Maresova; Jan Hrdina
Original assignee: Vyzkumny Ustav Bavlnarsky AS
Current assignee: Vyzkumny Ustav Bavlnarsky AS
Priority date: 1984-04-26
Filing date: 1985-03-13
Publication date: 1985-11-06
Also published as: CS242953B1; GB2158108B; CS308984A1; GB8506567D0; DE3509946C2; JPS60259637A; DE3509946A1

Abstract

An object of the invention is to eliminate the noxious effect of ultrasonic waves produced by pressure air ejected from a spinning tube (9) for manufacturing fiber bundle yarn. The tube (9) is followed by at least one expansion-and-absorption chamber (14) which is provided with air discharging means (18) arranged in the chamber jacket outside the range of direct air outlet as well as with a yarn outlet aperture (15) provided in the chamber front cover (16). In accordance with the invention, the ejected air flow is exposed to multiple, damping, rebounds against inner walls of said expansion-and-absorption chamber (14) and against said front cover (16) thereof. The chamber may be divided with the sub-chambers connected by an external duct. Air may be excluded from the chambers. <IMAGE>

Description

SPECIFICATION Pneumatically manufacturing fiber bundle yarn The invention relates to pneumatically manufacturing fiber bundle yarn.

The process of pneumatically manufacturing fiber bundle yarn consists in that a sliver of staple fibers is attenuated by a passage through a drawing frame into a ribbon-like formation having a fineness of yarn to be spun. Immediately downstream of the drawing frame, the ribbon is led into the axial bore of a spinning nozzle housing. A pressure air flow tangentially entering the axial nozzle bore produces therein an advancing whirl flow by which the ribbon is given a torsional moment whereby it is twisted to the form of yarn which is withdrawn by take-off rollers and finally cross-wound on a bobbin by winding means.Since a substantial portion of fibers in the ribbon is delivered from the drawing frame as a coherent formation, the ribbon, on its way between the nozzle and the take-off rollers, is untwisted again so that the coherent portion of fibers forming the core of future yarn remains twistless. Since, however, some fibers in the ribbon delivered from the drawing frame are not, at least by a part of their lengths, coherent with the other fibers, they are not given the same false twist as the fibers in the core but, on the contrary, they wrap around said core in the false twist untwisting zone. In this way there is produced a fibre bundle yarn structure wherein the strength of the fibrous core is not given by twist but by firmly wrapping the core by surface fibers.

With known pneumatic processes of manufacturing fibre bundle yarn the fibrous ribbon is effectively twisted in the spinning nozzle in that the air whirl flow the fibrous formation is exposed to, is ejected at a high speed out of the nozzle either through the axial bore, or through radial exhaust holes immediately into the ambient atmosphere.

A disadvantage of these processes is in that the ejected air flow carries high-frequency non-audible waves which are produced in the axial bore of spinning nozzle. Such ultrasonic waves having a high level of acoustic pressure freely propagate into the space of spinning mill and harm the health of attending personnel without being perceived by their organs of hearing.

It is known to provide the spinning nozzle with a hood, and the hooded space communicates with air withdrawing piping. In this way it is not possible to reduce, or even eliminate high-frequency wave effect because the hood is neither homogenous nor leakless; the outlet aperture for yarn is too large and, apart from this, the metal sheet hood is prone to oscillate.

It is an object of the present invention to obviate or mitigate the disadvantage of the above.

In accordance with one aspect of the invention there is provided a method of damping ultrasonic waves produced by a superatmospheric pressure air flow ejected from a spinning nozzle for manufacturing fiber bundle yarn, and withdrawn therefrom by air withdrawing means, wherein the ejected air flow, on its way from the nozzle outlet to the air withdrawing means, is exposed to multiple rebounds against inner walls of an expansionand-absorption chamber.

In accordance with another aspect of the invention there is provided apparatus for pneumatically manufacturing fiber bundle yarn, comprising a housing having an inlet opening and a following coaxial cylindrical duct leading into a spinning tube, at least one pressure air feeding pipe for supplying said tube with pressure air, and at least one outlet opening for discharging air from said tube, wherein the spinning tube is followed by an expansion-and-absorption chamber having an inner wall disposed opposite the or each of said air outlet openings said chamber being provided with air discharge means arranged beyond the reach of direct air discharge from the spinning tube and connected with air withdrawing means and with a yarn outlet aperture provided in a front cover masking the outlet side of the expansion-and-absorption chamber.

The invention is advantageous in that the harmful ultrasonic waves are substantially suppressed and dust, impurities and fiber fractions are prevented from reaching the surroundings of the apparatus, with no adverse effect on the spinning process.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying schematic drawings, in which: Figure 1 is an axial sectional view of a spinning nozzle having a single expansion-and-absorption chamber; Figure 2 is an axial sectional view of a spinning nozzle having two expansion-and-absorption chambers separated from each other by a separating wall; Figure 3 is an axial sectional view of a spinning nozzle with an alternative embodiment of the expansion-and-absorption chamber; and Figure 4 is an axial sectional view of a spinning nozzle having a fundamental and an additional expansion-and-absorption chamber which are separated from each other by a partition wall provided with an axial passage way.

A pneumatic spinning unit for manufacturing bundle yarn comprises a drafting mechanism such as of roller type, from which a sliver 8 of fibrous material is supplied by a pair of delivery rollers 1 to an associated spinning nozzle unit 2. Downstream of the latter there is provided a pair of takeoff rollers 3 for withdrawing a bundle yarn 4 which is then wound on a bobbin by conventional winding means (not shown).

The spinning nozzle unit 2 itself consists of a housing 5 in which a conically narrowing inlet opening 6 and further on a coaxial cylindrical duct 7 are provided. The duct 7 the diameter of which is as small as possible with respect to that of the processed fiber bundle 8, opens into a spinning tube 9 of a cylindrical, or conical configuration, having a slightly larger diameter than the cylindrical duct 7. The spinning tube 9 is ended by an out let opening 10. At the opposite end portion, adjacent the cylindrical duct 7, one or more pressure air feeding channels 11 tangentially open into the spinning tube 9. The channels 11 communicate with an annular air distrubuting chamber 12 arranged in the housing 5 coaxially with the spinning tube 9, and communicating via a socket 13 with an air piping, or immediately with a superatmospheric pressure source (not shown).

The spinning tube 9 merges into an expansionand-absorption chamber 14 the inner capacity of which is a multiple of that of said tube 9. The chamber 14 is completely confined by a jacket 17 and a front cover 16, and communicates with the ambient atmosphere only by an outlet aperture 15 provided in said cover 16 for the yarn withdrawal as well as by an air discharge socket 18 provided in said jacket 17.

The outlet opening 10 of the spinning tube 9 can open into the expansion-and-absorption chamber 14 either axially, as shown in Figure 1, or off-center. The chamber 14 can have a cylindrical, or another configuration such as of a polyhedron. The jacket 17 of the expansion-and-absorption chamber 14 can be manufactured separately and mounted onto the housing 5 of the spinning nozzle unit 2, as for example, by pressing on, or in another known manner. Alternatively, the jacket 17 can be made integrally with the housing 5, provided the latter is manufactured e.g. by machining, or from a cast piece.The embodiment of the expansion-and-absorption chamber 14 and the connection thereof to the spinning tube 9 can be made in different ways; thus, for instance, the chamber 14 can begin till from the outlet opening 10 of the spinning tube 9, or, more preferably as shown in Figure 1, it extends already from the housing 5 to the take-off rollers 3 and completely surrounds the spinning tube 9 also extending from said housing 5. Adjacent the pressure air feeding channels 11, the jacket 19 of the spinning tube 9 is provided with radial openings 20 through which the interior of said tube 9 communicates with the chamber 14.

The expansion-and-absorption chamber 14 as shown in Figure 1 is constituted by a single continuous confined space which communicates with the ambient atmosphere only by said aperture 15 in the cover 16 as well as by the air discharge socket 18 provided in the jacket 17 not opposite the radial openings 20. It, namely, is an object of the invention to cause the air flow discharged from the spinning tube 9 into the chamber 14, to rebound several times against inner walls 21 of the jacket 17 andlor against the front cover 16 of the chamber 14, before it has been ejected through the discharge socket 18.It is why the latter must not be provided in the front cover 16 opposite the outlet opening 10 of the spinning tube; otherwise, namely, the air would be allowed to flow directly into the ambient atmosphere so that the effect of damping harmful waves in the ultrasonic frequency range would get lost. The air discharge socket 18 should not be either provided in the jacket 17 within the reach of the air flow cone discharged from the outlet opening 10 so as to cause the air to rebound several times against the inner walls of the chamber 14 forming an obstacle thereto.

Figure 2 shows a more advantageous embodiment of the spinning nozzle 2, wherein two expansion-and-absorption chambers 14.1 and 14.2 are provided. These chambers are separated from each other by a separating wall 22. The chamber 14.1 begins at the outlet opening 10 of the spinning tube 9 wherein the separating wall 22 is provided, and extends up to the front cover 16 and the takeoff rollers 3, which embodiment corresponds to that shown in Figure 1. The second expansion-andabsorption chamber 14.2 is arranged upstream of the separating wall 22 so that its jacket 17 surrounds the jacket 19 of the spinning tube 9. While the outlet opening 10 of the spinning tube opens into the first chamber 14.1, the radial openings 20 provided in the spinning tube 9 open into the second chamber 14.2.In this embodiment, each of the chambers 14.1 and 14.2 is provided with its own air discharge socket 18.1 and 18.2, respectively. Although in the shown embodiment, the diameters of inner walls 21 of the two chambers 14.1 and 14.2 are alike, they can be stepped in various dimensions.

A still more preferred embodiment is shown in Figure 3. The spinning nozzle unit 2 is provided with the expansion-and-absorption chamber 14 corresponding to that shown in Figure 1, said chamber 14 being followed by an additional expansion-and-absorption chamber 23 which is separated from the chamber 14 being followed by an additional expansion-and-absorption chamber 23 which is separated from the chamber 14 by a partition wall 24 spaced apart from the outlet opening 10. The partition wall 24 is provided with a passage way 25 which is coaxial to and has a larger diameter than the outlet opening 10. The diameter of a conical air flow ejected out of the outlet opening 10, and by the distance between the partition wall 24 and the outlet opening 10 can be either constant, or adjustable.In this case the partition wall 24 is usually made arrestable in the adjusted position by any one of conventional means.

The afore-described embodiment is advantageous in case that it is necessary to obtain different pressure values in the spinning tube 9 and in the expansion-and-absorption chambers 12 and 23, respectively. The additional chamber 23 is provided with its own air discharge socket 19.3 which is connected to an air withdrawing piping 26 while the air discharge socket 18 in the chamber 14 is connected to an air withdrawing piping 27. The two pipings 26 and 27 serve for connecting the respective chamber interiors with a collecting receptacle 29 in which an atmospheric air pressure, or a vacuum is produced by a source 33. Alternatively, the connections of the two pipings 26, 27 can be combined in that, for example, the piping 27 communicates via socket 18 with the receptacle 29 with the atmospheric air pressure while the piping 26 leading from the additional expansion-and-absorption chamber 23 communicates via socket 18.3 with the vacuum source 33 whereby a quicker withdrawal of spent air is achieved. Also other combinations of this kind are possible.

To raise the ultrasonic wave damping effect of the expansion-and-absorption chambers 14 and 23, respectively, it is advisable to provide the inner walls 21 thereof with a lining 28 of a suitable absorbing porous material such as polyurethane.

Similarly, the chambers 14 and 23, respectively, or at least the jacket 17, should be made of an ultrasonics damping and absorbing material such as polyamide.

The distance between the radial openings 20 and the inner walls 21 of the expansion-and-absorption chamber, and the distance between the outlet opening 10 of the spinning tube 9 and the front cover 16 are to be chosen so as to provide an effective damping of ultrasonic waves by rebounding and absorption, and particularly as close as possible to the wave origin, and thus to prevent the waves from propogating into the ambient atmosphere. In the drawings, some preferred embodiments of expansion-and-absorption chambers forming parts of the spinning nozzle units are shown.

The expansion-and-absorption chambers 14 and 23 of all of the afore-described embodiments can be provided with a cleaning opening 34 which is periodically supplied with a pressure air flow for stripping dust and impurities sedimenting on the jacket 19 of the spinning tube 9 and on the inner walls 21 of the expansion-and-absorption chamber 14 and 23, and for withdrawing them via sockets 18, 18.3 into the collecting receptacle 29. It is also advantageous to provide the air withdrawing pipings 26, 27 with control means 30 for adjusting the amount and pressure of air to be withdrawn relative to the pressure of air supplied to the spinning tube 9. To allow the access to the interior of the expansion-and-absorption chamber 14 and 23, respectively, the front cover 16 is made removable such as by means of screw joint.

The embodiment shown in Figure 4 corresponds to that in Figure 3, except that the two chambers 14 and 23 are interconnected by a bypass duct 31 while only the additional expansion-and-absorption chamber 23 is provided with the air discharge socket 18.3 connected to the air withdrawing piping 26.

The spinning nozzle unit operates as follows: The process of manufacturing a fiber bundle yarn consists in that a ribbon-like fibrous formation of a yarn fineness attenuated in a drawing frame from the fibrous sliver 8, is advanced by the delivery roller pair 1 to the sucking inlet opening 6 and further on through the cylindrical duct 7 into the spinning tube 9 of the spinning nozzle unit 2. After passing said duct 7, the fibrous ribbon is exposed in the spinning tube 9 to an air whirl flow produced by the superatmospheric pressure air tangentially supplied into the spinning tube 9 through channels 11. The speed of said air whirl flow reaches supersonic values whereby ultrasonic waves propagate in the air.A portion of air flow is ejected from the outlet opening 10 of the spinning tube 9 into the expansion-and-absorption chamber 14 in which the ultrasonic waves are damped and from which air together with impurities and fiber fragments is withdrawn through the discharge socket 18 and the piping 27 into the collecting receptacle 29. Thus only a small portion of ultrasonic waves escapes into the ambient atmosphere through the axial outlet aperture 15 for the yarn 4.

A second air flow portion is withdrawn from the spinning tube 9 through radial openings 20 into the interior of the expansion-and-absorption cham ber 14 wherein the ultrasonic waves are also damped. The air flow ejected from said openings 20 accelerates and raises the twisting effect of the revolving air on the yarn 4. Due to the coherence of the fiber formation, the twisting effect of the air whirl flow creates a false twist between the nip of the delivery rollers 1 and the nip of the take-off rollers 3 so that the delivered yarn is theoretically twistless.In fact, however, a portion of fibers on the surface of the formation (i.e. the so-called fibers with free ends) loses in the region of the nip of rollers 1 the cohesion with the other fibers so that this portion is not given any false twist in the so-called twist triangle but, on the contrary, it is given a true twist, downstream of the spinning tube 9, during the untwisting of the fibrous formation, and wraps around the untwisted core. Thus the structure of fiber bundle yarn is formed already in the nip of take-off rollers 3. Yarn 4 is crosswound on a bobbin (not shown). The ultrasonic wave damping is achieved in that the ejected air, before entering the discharge socket or sockets 18, is caused to rebound against at least one inner wall 21 of the expansion-and-absorption chamber disposed opposite the air flow.In an alternative process, the air flow entering the expansion-andabsorption chamber 14 is led out of it thorugh the axial passage way 25 into the additional chamber 23, owing to an ejection effect of a direct sectional air flow led from the spinning tube 9 immediately into said additional expansion-and-absorption chamber 23 through said passage way 25 which interconnects the two chambers 14 and 23.

The advantageous effect of the invention was proved by a practical experiment wherein 13 tex fiber bundle yarn was made of 3.5 ktex sliver containing 65% of PES fibers and 35% of cotton fibers.

The spinning nozzle unit 2 according to Figure 3 with two expansion-and-absorption chambers 14 and 23 was tested at the yarn take-off speed of 150 meters per minute. When applying an air pressure of 0.3 MPa in the spinning tube 9, a high-grade yarn was obtained while the dust content in the ambient atmosphere was substantially reduced, and, what is mostly important, the original maximum sound pressure level of 102 dB within the band of from 20 to 40 kHz dropped to 77 dB.

The superatmospheric air whirl flow produced in the spinning tube 9 is ejected into the expansionand-absorption chamber 14, 14.1, 14.2 or 23, respectively, which communicates with an atmospheric air pressure or a vacuum source. Moreover, the vacuum substantially supports the twisting effect of the whirl on yarn. In the chambers 14, 14.1, 14.2 or 23, respectively, an expansion and turbu lence of whirl flow take place so that the initial or first portion of ultrasonic waves is absorbed by multiple rebounds against the inner walls 21 of said chambers. Another portion thereof is then damped on walls of air withdrawing pipings 26, 27 during the withdrawal of spent air flow outside the attendance space of the spinning nozzle unit.

As hereinabove set forth, the spinning tube 9 is provided, apart from the outlet opening 10, with one or more radial openings 20. As can be seen in Figure 2, an air flow portion is ejected from the spinning tube 9 through said openings 20 into the expansion-and-absorption chamber 14.2. This ejection promotes further the yarn twisting effect of the whirl. In case the chambers 14.1 and 14.2 are hermetically separated from each other, their functions are practically the same, except that in the chamber 14.2, moreover the ultrasonic waves produced by air flow or flows ejected from the radial openings 20, are damped. Also in this case the spinning process is effectively supported when the expansion-and-absorption chamber 14.2 communicates via piping 27 with a vacuum source.

In another preferred embodiment of the spinning nozzle unit 2 comprising the chamber 14 and the additional chamber 23 as shown in Figures 3 and 4, the function of the passage way consists in that the air flow discharged from the spinning tube 9 through radial openings 20 into the expansion-andabsorption chamber 14 is partially sucked, due to an ejection effect in the interspace 32, into the interior of the additional chamber 23. In this way the efficiency of damping ultrasonic waves further increases.

The purpose of interconnection of the two expansion-and-absorption chambers 14, 23 by the bypass duct 31 (Figure 4) consists in that the air pressure in the chamber 14 is, due to the aforementioned ejection effect in the interspace 32, lower than that in the chamber 23 so that a cyclic air streaming via bypass duct 31 is produced between the two chambers 14 and 23. Owing to this streaming, a multiple ultrasonic wave damping effect arises.

Claims

1. A method of damping ultrasonic waves produced by a superatmospheric pressure air flow ejected from a spinning nozzle for manufacturing fiber bundle yarn, and withdrawn therefrom by air withdrawing means wherein the ejected air flow, on its way from the nozzle outlet to the air withdrawing means, is exposed to multiple rebounds against inner walls of an expansion-and-absorption chamber.

2. A method as claimed in claim 1, wherein the air flow ejected into the expansion-and-absorption chamber is withdrawn therefrom through an axial opening into a following additional expansion-andabsorption chamber, due to an ejection effect of a direct sectional air flow led from the spinning tube immediately into said additional chamber through an axial passageway interconnecting the two expansion-and-absorption chambers.

3. A method as claimed in claim 2, wherein the sectional air flow recirculates from said additional into the primary expansion-and-absorption chamber.

4. Apparatus for pneumatically manufacturing fiber bundle yarn, comprising a housing having an inlet opening and a following coaxial cylindrical duct leading into a spinning tube, at least one pressure air feeding pipe for supplying said tube with pressure air, and at least one outlet opening for discharging air from said tube, wherein the spinning tube is followed by an expansion-and-absorption chamber having an inner wall disposed opposite the or each of said air outlet openings, said chamber being provided with air discharge means arranged beyond the reach of direct air discharge from the spinning tube and connected with air withdrawing means, and with a yarn outlet aperture provided in a front cover masking the outlet side of the expansion-and-absorption chamber.

5. Apparatus as claimed in claim 4, wherein the expansion-and-absorption chamber is subdivided by a separating wall aligned with the central air outlet opening of the spinning tube, into a first chamber remote from the housing, and a second chamber adjacent said housing, said second chamber being supplied with air discharged from radial openings provided in the spinning tube.

6. Apparatus as claimed in claim 4, wherein the expansion-and-absorption chamber is subdivided into a main chamber and an additional chamber by a partition wall which is spaced apart from the air outlet opening of the spinning tube by an interspace and is provided with a passage way oriented opposite said outlet opening, said additional expansion-and-absorption chamber being disposed downstream of said partition wall.

7. Apparatus as claimed in claim 6, wherein the position of the partition wall relative to the outlet opening of the spinning tube is adjustable.

8. Apparatus as claimed in claim 6 or 7, wherein the additional expansion-and-absorption chamber communicates via a bypass duct with the main expansion-and-absorption chamber.

9. Apparatus as claimed in any one of claims 4 to 8, wherein the inner walls of the expansion-andabsorption chamber are provided with a lining of a sound absorbing material.

10. Apparatus as claimed in any one of claims 4 to 8, wherein at least the jacket of the expansionand-absorption chamber is made of a second absorbing material.

11. Apparatus as claimed in any one of claims 4 to 10, wherein the expansion-and-absorption chamber is provided with a cleaning opening for releasing sedimented dust by pressure air.

12. Apparatus as claimed in any one of claims 4 to 11, wherein piping for withdrawing air from the expansion-and-absorption chamber is provided with control means.

13. A method of damping ultrasonic waves produced by a superatmospheric air flow ejected from a spinning nozzle for manufacturing fibre bundle yarn, substantially as hereinbefore described with reference to Figure 1 of the accompanying draw ings.

14. A method of damping ultrasonic waves produced by a superatmospheric air flow ejected from a spinning nozzle for manufacturing fibre bundle yarn, substantially as herein before described with reference to Figure 2 of the accompanying drawings.

15. A method of damping ultrasonic waves produced by a superatmospheric air flow ejected from a spinning nozzle for manufacturing fibre bundle yarn, substantially as herein before described with reference to Figure 3 of the accompanying drawings.

16. A method of damping ultrasonic waves produced by a superatmospheric air flow ejected from a spinning nozzle for manufacturing fibre bundle yarn, substantially as herein before described with reference to Figure 4 of the accompanying drawings.

17. Apparatus for pneumatically manufacturing fiber bundle yarn, substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

18. Apparatus for pneumatically manufacturing fiber bundle yarn, substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.

19. Apparatus for pneumatically manufacturing fiber bundle yarn, substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.

20. Apparatus for pneumatically manufacturing fiber bundle yarn, substantially as hereinbefore described with reference to Figure 4 of the accompanying drawings.