Spinning unit of an air jet spinning machine and the operation of such a machine

Abstract

A method and system for operating an air jet spinning machine, that features at least one spinning unit with one spinning nozzle for producing a yarn. During normal operation of the spinning unit, a fiber composite is fed to the spinning nozzle through an inlet and in a predefined transport direction. The fiber composite within a vortex chamber of the spinning nozzle receives a twist with the assistance of a vortex air flow, such that a yarn is formed from the fiber composite, which leaves the spinning nozzle through an outlet. After an interruption in yarn production, a piecing process is carried out, with which one yarn end on the spool side moves counter to the transport direction through the spinning nozzle, is overlaid with one end of the fiber composite after passing through the spinning nozzle and, together with this, is brought through the inlet into the spinning nozzle. After conclusion of the piecing process, the production of yarn is continued through the resumption of normal operation. During the piecing process, at least temporarily, additive is applied at the end of the fiber composite.

Claims

1. A method for operating an air jet spinning machine, wherein the air jet spinning machine features at least one spinning unit with a spinning nozzle for producing a yarn, the method comprising: during normal operation of the spinning unit, feeding a fiber composite to the spinning nozzle through an inlet and in a predefined transport direction, wherein the fiber composite within a vortex chamber of the spinning nozzle receives a twist with the assistance of a vortex air flow, such that a yarn is formed from the fiber composite, the yarn leaving the spinning nozzle through an outlet; spooling the yarn on a sleeve with assistance of a spooling device; carrying out a piecing process after an interruption in the yarn production wherein a yarn end from a spool side of the spinning nozzle is moved counter to the transport direction through the spinning nozzle, is overlaid with an end of the fiber composite after passing through the spinning nozzle, the overlaid yarn end and fiber composite end brought through the inlet into the spinning nozzle; during the piecing process, applying an additive to the end of the fiber composite; and after conclusion of the piecing process, resuming production of the yarn in the normal operation.

2. The method according to claim 1, wherein the additive is applied at the end of the fiber composite after it has been overlaid with the yarn end.

3. The method according to claim 2, wherein the additive is applied in front of the inlet of the spinning nozzle viewed in the transport direction.

4. The method according to claim 1, wherein a volume flow of the fed additive during the piecing process is between 0.001 ml/min and 2.0 ml/min, or a mass flow of the fed additive during the piecing process is between 0.001 g/min and 2.0 g/min.

5. The method according to claim 4, wherein during the addition of additive, the volume flow or mass flow of the additive is regulated with assistance of a valve that is opened and closed at least once per second such that the additive fed to the valve passes through the valve in a pulse-like manner.

6. The method according to claim 4, wherein during the piecing process, the volume flow or mass flow of the additive is higher than that during the normal operation of the spinning unit following the piecing process.

7. The method according to claim 4, wherein during the piecing process, the volume flow or mass flow of the additive is reduced compared to an initial amount at start of the piecing operation.

8. The method according to claim 7, wherein the reduction of the volume flow or mass flow of the additive is continuous through the piecing operation.

9. An air jet spinning machine, comprising: a spinning unit with a spinning nozzle for producing a yarn from a fiber composite fed to the spinning nozzle, the spinning nozzle comprising an inlet for the fiber composite; an internal vortex chamber defined in the spinning nozzle; a yarn formation element protruding into the vortex chamber; an outlet for the yarn produced in the vortex chamber with assistance of a vortex air flow generated in the vortex chamber; an additive supply allocated to the spinning unit and configured to apply an additive at an end of the fiber composite present after an interruption in the yarn production; a control unit in operative connection with the additive supply and configured to, after an interruption in yarn production, initiate a piecing process wherein additive is applied at the end of the fiber composite.

10. The air jet spinning machine according to claim 9, wherein the additive supply further comprises a feed valve, the control unit in operative connection with the feed valve to regulate a volume flow of the additive during the piecing process is between 0.001 ml/min and 2.0 ml/min, or a mass flow of the additive during the piecing process is between 0.001 g/min and 2.0 g/min, wherein the valve is further opened and closed at least once per second such that the additive fed to the valve passes through the valve in a pulse-like manner.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Additional advantages of the invention are described in the following embodiments. This following is shown, in each case schematically:

(2) FIG. 1 a schematic view of a spinning unit of an air jet spinning machine in accordance with the invention during the normal operation of the same,

(3) FIG. 2 a sectional view of a spinning nozzle of a spinning unit of an air jet spinning machine in accordance with the invention,

(4) FIG. 3 the spinning unit in accordance with FIG. 1 after an interruption of yarn production,

(5) FIG. 4 the spinning unit in accordance with FIG. 1 after the return of the yarn end counter to the transport direction, and

(6) FIG. 5 the spinning unit in accordance with FIG. 1 during a piecing process with the application of additive at the end of the fiber composite.

DETAILED DESCRIPTION

(7) Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.

(8) FIG. 1 shows a cut-out of a spinning unit of an air jet spinning machine in accordance with the invention (whereas the air jet spinning machine may, of course, feature a multitude of spinning units, preferably arranged in a manner adjacent to each other). When required, the air jet spinning machine may include a drafting system 13 with several drafting system rollers 12, which is supplied with a fiber composite 3 in the form of, for example, a doubled sliver. Furthermore, the spinning unit that is shown includes a spinning nozzle 1 with an internal vortex chamber 5, which is shown in more detail in FIG. 2, in which the fiber composite 3 or at least a part of the fibers of the fiber composite 3 is, after passing through an inlet 4 of the spinning nozzle 1, provided with a twist (the exact mode of action of the spinning unit is described in more detail below).

(9) Moreover, the air jet spinning machine may include a pair of draw-off rollers 14 downstream of the spinning nozzle 1 that features two draw-off rollers 14 along with a spooling device 7 downstream of the pair of draw-off rollers for the spooling of the yarn 2 leaving the spinning unit onto a sleeve. The spinning unit in accordance with the invention need not necessarily feature a drafting system 13. The pair of draw-off rollers is also not absolutely necessary, or may be replaced with an alternative draw-off unit.

(10) Generally, the spinning unit that is shown works according to an air spinning process. For the formation of the yarn 2, the fiber composite 3 is led in a transport direction T through a fiber guide element 15, which is provided with an inlet opening forming the specified inlet 4, into the vortex chamber 5 of the spinning nozzle 1. At that point, it receives a twist; that is, at least one part of the free fiber ends of the fiber composite 3 are captured by a vortex air flow that is generated by air nozzles 18 correspondingly arranged in a vortex chamber wall 5 surrounding the vortex chamber 5, whereas the air nozzles 18 are fed with compressed air through an air distributor 17 (which, for example, is ring-shaped and is connected to an air supply line 16). Thereby, a part of the fibers is pulled out of the fiber composite 3 at least to some extent, and wound around the top of the yarn formation element 10 protruding into the vortex chamber 5. Given that the fiber composite 3 is extracted through an inlet mouth 29 of the yarn formation element 10 through a draw-off channel 22 arranged within the yarn formation element 10, out of the vortex chamber 5, and finally through an outlet 6 out of the spinning nozzle 1, the free fiber ends are also ultimately drawn in the direction of the inlet mouth 29 and thereby, as so-called winding fibers, loop around the core fiber running in the centerresulting in a yarn 2 featuring the desired twist. The compressed air introduced through the air nozzles 18 leaves the spinning nozzle 1 ultimately through the draw-off channel 22 along with an air outlet 19 that might be present, which, when required, may be connected to a vacuum power source.

(11) With regard to the air nozzles 18, it must also be mentioned at this point, purely as a matter of precaution, that they typically should be generally aligned in such a manner that the escaping air streams are unidirectional, in order to generate a unidirectional air flow with a rotational direction. Preferably, the individual air nozzles 18 are in this case arranged in a manner that is rotationally symmetric to each other, and tangentially flow into the vortex chamber 5.

(12) During yarn production, it cannot be ruled out that, for various reasons, thick or thin parts in the yarn 2 arise. In this case, yarn production is interrupted by the control unit 25, such that a yarn end 23 on the spool side arises. After the interruption of yarn production, the yarn end 23 may be located on the surface of the spool found on the spooling device 7 or in the area between the spooling device 7 and the spinning nozzle 1, preferably between the outlet 6 of the same and the draw-off rollers 14 (see FIG. 3). During yarn production, unwanted yarn breakages may also arise, which likewise have the consequence of a corresponding yarn end 23 along with an end 24 of the fiber composite 3 coming to a stop in the area of the correspondingly stopped drafting system 13.

(13) In order to resume yarn production (that is, the normal operation of the respective spinning unit), the specified yarn end 23 must be connected to the end 24 of the fiber composite 3. For this purpose, it is provided that the yarn end 23 is fed counter to the transport direction T through the spinning nozzle 1, whereas, for this purpose, the spool found in the spooling device 7 is driven backwards in order to release a corresponding quantity of yarn. The yarn end 23 or a yarn end 23 newly arising through the removal of the yarn section featuring the yarn flaw is, at this stage, conveyed with the assistance of mechanical or pneumatic means in the area of the outlet 6 of the spinning nozzle 1, and is sucked into this with the assistance of a negative pressure prevailing in the draw-off channel 22. With the assistance of a corresponding air flow, the further conveying of the yarn end 23 ultimately takes place through the inlet 4 of the spinning nozzle 1, until it is located in the area in front of the spinning nozzle 1 (viewed in the transport direction T). In particular, it is advantageous here if the yarn end 23 is moved until it is located between the two drafting system rollers 12 of the drafting system 13 on the outlet side (for this purpose, the specified stretching unit rollers 12 are moved away from each other prior to the passing of the yarn end 23, in order to enable the specified passing; after passing the yarn end 23, they are finally brought back into the position shown in FIG. 4, in which the yarn end 23 is fixed in a clamping manner).

(14) In the next step, the drafting system rollers 12, the draw-off rollers 14 and the spooling device 7 on the outlet side and fixing the yarn end 23 are put back into operation, such that the yarn end 23 moves in the transport direction T. At the same time or temporarily postponed, the remaining drafting system rollers 12 are also put back into motion, whereas the beginning of their rotation along with the corresponding rotational speed are adjusted in such a manner that the end 24 of the fiber composite 3 arrives in overlapping contact with the yarn end 23 and, together with it, can be drawn into the spinning nozzle 1.

(15) In order to strengthen the connection area 27 (that is, the overlap area between the yarn end 23 and the end 24 of the fiber composite 3) or to improve the fiber orientation in this area compared to the state of the art, in accordance with the invention, it is proposed that an additive 8 is delivered at the end 24 of the fiber composite 3.

(16) For this purpose, the spinning unit features an additive supply 11, which preferably includes one or more additive reservoirs 21 that supply an additive 8 (for example, in the form of pressure tanks) along with one or more additive supply lines 20 (which are preferably at least partially flexible), through which the respective additive reservoir 21 is in fluid connection with an additive outlet opening 26 arranged in the area of the spinning nozzle 1 (with regard to a possible additive 8, reference is made to the previous description). Preferably, the additive outlet opening 26 is arranged in the area of the inlet 4 of the spinning nozzle 1 or the specified fiber guide element 15. In particular, the delivery should take place at a location that is passed by the connection area 27 (yarn end 23-end 24 of the fiber composite 3), in order to strengthen or stabilize this area through the additive 8. The quantity of the delivered additive 8 may take place with the assistance, for example, of a valve 9 integrated, for example, into the additive supply line 20 (with regard to possible details of valve 9, reference is made to the above description).

(17) The invention is not limited to the illustrated and described embodiments. Variations within the framework of the patent claims, such as any combination of the described characteristics, even if they are illustrated and described in different parts of the description or the claims or in different embodiments.

LIST OF REFERENCE SIGNS

(18) 1 Spinning nozzle 2 Yarn 3 Fiber composite 4 Inlet of the spinning nozzle 5 Vortex chamber 6 Outlet of the spinning nozzle 7 Spooling device 8 Additive 9 Valve 10 Yarn formation element 11 Additive supply 12 Drafting system roller 13 Drafting system 14 Draw-off roller 15 Fiber guide element 16 Air supply line 17 Air distributor 18 Air nozzle 19 Air outlet 20 Additive supply line 21 Additive reservoir 22 Draw-off channel 23 Yarn end 24 End of the fiber composite 25 Control unit 26 Additive outlet opening 27 Connection area between the yarn end and the end of the fiber composite 28 Inlet mouth of the yarn formation element T Transport direction