Air jet spinning machine and method for operating the same

Abstract

A method for operating an air jet spinning machine having at least one spinning unit with one spinning nozzle for producing a yarn is provided. During the operation of the spinning unit, the spinning nozzle feeds a fiber composite through an inlet 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. With the assistance of at least one sensor system, the yarn leaving the outlet is monitored with regard to defined yarn flaws. The production of yarn is interrupted upon the detection of a corresponding yarn flaw. Between the detection of the specified yarn flaw and the interruption of the yarn production, a cleaning process is carried out during which an additive is fed to the spinning unit and is applied to the fiber composite and/or the yarn produced from the fiber composite and/or on parts of the spinning nozzle.

Claims

1. A method for operating an air jet spinning machine having a spinning unit with a spinning nozzle for producing a yarn, the method comprising: during 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 and leaves the spinning nozzle through an outlet; monitoring the yarn leaving the outlet with at least one sensor system with regard to defined yarn flaws; interrupting production of the yarn upon the detection of a corresponding yarn flaw; between detection of the specified yarn flaw and interruption of the yarn production, performing a cleaning process for a specified period of time during which an additive is fed to a location either within the spinning nozzle or upstream of the spinning nozzle and is applied to one or more of: (1) the fiber composite; (2) the yarn produced from the fiber composite; or (3) parts of the spinning nozzle.

2. The method according to claim 1, wherein the sensor system is deactivated during the cleaning process and evaluation of measured values delivered by the sensor system is interrupted during the specified period of time.

3. The method according to claim 1, wherein on the basis of measured values delivered by the sensor system during the cleaning process, one or both of a qualitative or quantitative monitoring of the additive feed takes place.

4. The method according to claim 1, wherein after the interruption of yarn production, with the assistance of a yarn removal unit, a yarn section containing the yarn flaw and a yarn section produced during the cleaning operation are removed from the yarn, and further comprising performing a subsequent piecing process wherein an end section of the remaining yarn is guided through the spinning nozzle against the transport direction, is brought into contact with the fiber composite and is subsequently introduced into the spinning nozzle in the transport direction together with the fiber composite.

5. The method according to claim 1, wherein a yarn delivery speed of the spinning nozzle during the cleaning process is less than the yarn delivery speed that prevails during a normal operation of the spinning nozzle preceding detection of the yarn flaw.

6. The method according to claim 1, wherein, during the cleaning process, a yarn is produced having a length-related mass that is greater than the length-related mass of the yarn produced during a normal operation of the spinning nozzle preceding detection of the yarn flaw.

7. The method according to claim 6, wherein the length-related mass of the yarn produced during the cleaning process is less than 30 Nm.

8. The method according to claim 1, further comprising performing the cleaning process at defined points in time regardless of detection of a yarn flaw that leads to interruption of yarn production.

9. The method according to claim 1, further comprising performing the cleaning process at one or all of: (1) a defined period of time has elapsed since the last cleaning process; (2) a predefined minimum length of yarn has been produced; or (3) a predefined minimum quantity of yarn has been produced.

10. The method according to claim 1, wherein a volume fed flow of the additive is between 0.001 ml/min and 7.0 ml/min.

11. 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 further comprising; an inlet for the fiber composite; an internal vortex chamber; a yarn formation element protruding into the vortex chamber; an outlet for the yarn produced inside the vortex chamber with assistance of a vortex air flow; the spinning unit further comprising: a sensor system configured to monitor the yarn leaving the outlet during the operation of the spinning unit with regard to defined yarn flaws; a control unit that interrupts production of the yarn upon detection of a corresponding yarn flaw; an additive supply allocated to the spinning unit and located such that an additive is supplied to a location either within the spinning nozzle or upstream of the spinning nozzle during operation of the spinning unit; the control unit further configured to initiate a cleaning process between detection of the specified yarn flaw and interruption of yarn production, during which the additive is fed to the spinning unit by the additive supply; and wherein the additive is applied to one or all of (1) the fiber composite; (2) the yarn produced from the fiber composite; or (3) parts of the spinning nozzle.

12. The air jet spinning machine according to claim 11, wherein the control unit is connected to the sensor system and is configured to operate the air jet spinning machine under consideration of measured values transmitted by the sensor system.

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 is a side view of a spinning unit of an air jet spinning machine in accordance with the invention during normal operation;

(3) FIG. 2 is a partially cut cut-out of a spinning unit of an air jet spinning machine in accordance with the invention;

(4) FIG. 3 is the view of FIG. 1 after the conclusion of a cleaning process; and

(5) FIG. 4 is various cut-outs of a yarn.

DETAILED DESCRIPTION

(6) 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.

(7) 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 with several drafting system rollers 13, which is supplied with a fiber composite 3 in the form of, for example, a doubled sliver (for reasons of transparency, only one of the drafting system rollers 13 that is shown is provided with a reference sign). Furthermore, the spinning unit shown includes a spinning nozzle 2 with an internal vortex chamber 5 (see FIG. 2), in which the fiber composite 3 or at least a part of the fibers of the fiber composite 3 is, after passing an inlet 4 of the spinning nozzle 2, provided with a twist (the exact mode of action of the spinning unit is described in more detail below).

(8) Moreover, the air jet spinning machine may include a pair of draw-off rollers 24 downstream of the spinning nozzle 2, along with a spooling device 1 downstream of the pair of draw-off rollers 24 for the winding of the yarn 6 leaving the spinning nozzle 2 on a sleeve. The spinning unit needs not necessarily feature a drafting system. The pair of draw-off rollers 24 is also not absolutely necessary.

(9) Generally, the spinning unit shown works according to an air jet spinning process. For the formation of the yarn 6, the fiber composite 3 is led into the vortex chamber 5 of the spinning nozzle 2, in a predetermined transport direction T, through a fiber guide element 23, which is provided with an inlet opening forming the specified inlet 4 and shown in FIG. 2. At that point, it receives a twist; that is, at least a part of the free fiber ends 10 of the fiber composite 3 (see FIG. 4) is captured by a vortex air flow that is generated by air nozzles 19 correspondingly arranged in a vortex chamber wall surrounding the vortex chamber 5 (the air nozzles 19 are preferably provided with compressed air through an air supply line 18, which leads into an air supply chamber 17 connected to the air nozzles 19). 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 21 protruding into the vortex chamber 5. Given that the fiber composite 3 is drawn off through an inlet mouth of the yarn formation element 21 via a draw-off channel 20 arranged within the yarn formation element 21, out of the vortex chamber 5, and finally through an outlet 7 out of the spinning nozzle 2, the free fiber ends 10 are also ultimately drawn in the direction of the inlet mouth and thereby, as so-called winding fibers, loop around the core fibers running in the centerresulting in a yarn 6 featuring the desired twist. The compressed air introduced through the air nozzles 19 leaves the spinning nozzle 2 ultimately through the draw-off channel 20 along with an air outlet 25 that might be present, which, when required, may be connected to a vacuum power source.

(10) In general, it must be clarified at this point that the produced yarn 6 generally comprises any fiber composite 3, which is characterized by the fact that an external part of the fibers (so-called winding fibers) is looped around an internal part of the fibers that is preferably untwisted or, where required, twisted, in order to impart the desired strength to the yarn 6.

(11) Furthermore, the spinning unit is allocated with an additive supply 8, which includes one or more additive reservoirs 15 along with one or more additive supply lines 14, which are preferably at least partially flexible, through which the respective additive reservoir 15 is in fluid connection with an additive delivery 22 arranged in the area of the fiber guide element 23 or within the spinning nozzle 2 (with regard to possible additives 9, reference is made to the prior description).

(12) In principle, the additive 9 can be delivered to a different place. While FIG. 2 shows an embodiment with which the additive delivery 22 is located in the area of the inlet 4 of the spinning nozzle 2 (such that the additive 9 can be applied to the fiber composite 3), the additive 9 can also be added to the compressed air introduced through the air nozzles 19. Thereby, the entry of the additive 9 takes place, for example, through the air supply line 18 or the specified air supply chamber 17, which runs, for example, in a ring form around the wall bounding the vortex chamber 5 and through which the air nozzles 19 are supplied with compressed air. Finally, it is also possible to introduce the additive 9 through the draw-off channel 20.

(13) In order to deliver the additive 9 through the additive delivery 22 in a manner that is precise and highly reproducible, and also to adjust the delivered volume flow or mass flow of the additive 9 to the respective circumstances, the additive supply 8 also includes at least one dispensing unit 16, which is preferably integrated into the corresponding additive supply line 14, and additive 9 thus flows through it.

(14) In principle, it would be possible to apply the additive 9 in predefined time intervals to the yarn 6 and/or the fiber composite 3, in order to clean the spinning unit on the inside through the contact between the fiber composite 3 or the yarn 6 and the surface sections of individual areas of the spinning nozzle 2 coming into contact with it.

(15) However, within the framework of the present invention, it is proposed that additive 9, or additive 9 in an increased quantity compared to normal operation, is then applied to the fiber composite 3 and/or the yarn 6 for the purpose of the specified cleaning, if the sensor system shown in FIGS. 1 and 3 (which may include one or more optical and/or capacitive sensors) detects a yarn flaw 26 in the yarn 6, which is formed in such a manner that it cannot be tolerated in the finished yarn coil.

(16) After such a yarn flaw 26 has been detected, it is provided that the production of the yarn 6 is not to be immediately interrupted to carry out a clearer cut. Rather, yarn production is continued, whereas, in order to clean the spinning nozzle 2 at this stage, the quantity of additive compared to normal operation increases. After a certain period of time or after a certain yarn length, the production of yarn is finally interrupted, which results in a yarn end that is located between the outlet 7 of the spinning nozzle 2 and the pair of output rollers 24 or within the spinning nozzle 2.

(17) This yarn end ultimately may be captured by the yarn removal unit 12 (which may include, for example, a suction spout). If the coil of the spooling device 1 rotates in reverse until the yarn section featuring the yarn end is located in the yarn removal unit 12, it is ensured that the yarn flaw 26, and the yarn section produced after the detection of the yarn flaw 26 and thus during the cleaning process, are no longer located on the yarn coil of the spooling device 1. With the assistance of a separation unit, the yarn section located in the yarn removal unit 12 (see FIG. 3) can finally be separated from the remaining yarn 6 and disposed of.

(18) Finally, the new yarn end, created in this manner, of the qualitatively error-free yarn 6 found on the yarn coil is guided through the spinning nozzle 2 against the transport direction T, is brought into contact with the fiber composite 3 and is introduced, together with this, into the vortex chamber 5 in the transport direction T (=piecing process), in order to resume the normal operation of the spinning unit.

(19) Finally, FIG. 4 shows three yarn sections in a purely schematic manner. As FIG. 4a) shows, the yarn produced during normal operation without the addition of additive has a certain degree of hairiness; that is, a part of the free fiber ends 10 is set outwards. However, if the fiber composite 3 or the yarn 6 is wetted with additive 9, at least one part of such fiber ends 10 is laid out on the remaining yarn body (see FIG. 4b)), such that the addition of additive can be detected with the assistance of an optical sensor. The mass of the yarn 6 can likewise increase through the addition of additive, such that this can be detected and monitored for quantity with the assistance of a capacitive sensor. FIG. 4 c) schematically shows that the additive 9 may also be present in bead form, if the additive 9 is added in a pulse-like manner. In any case, optical and/or capacitive sensors would be suitable for monitoring the addition of additive in terms of quality and/or quantity during normal operation, and in particular during the cleaning process.

(20) The invention is not limited to the illustrated and described embodiments. Variations in the patent claims are possible, 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

(21) 1 Spooling device 2 Spinning nozzle 3 Fiber composite 4 Inlet 5 Vortex chamber 6 Yarn 7 Outlet 8 Additive supply 9 Additive 10 Free fiber end 11 Sensor system 12 Yarn removal unit 13 Drafting system roller 14 Additive supply line 15 Additive reservoir 16 Dispensing unit 17 Air supply chamber 18 Air supply line 19 Air nozzle 20 Draw-off channel 21 Yarn formation element 22 Additive delivery 23 Fiber guide element 24 Pair of output rollers 25 Air outlet 26 Yarn flaw T Transport direction