Air jet spinning machine and method for operating it

Abstract

A method is provided to operate an air jet spinning machine, having at least one spinning unit with a spinning nozzle for manufacturing yarn, in which a fiber strand is fed to the spinning nozzle through an inlet and is imparted a twist inside a vortex chamber of the spinning nozzle by means of a swirled air current so that a yarn is formed from the fiber strand. An additive is added with an additive dispenser to the spinning unit while the air jet spinning machine is operating and applied on the fiber strand or on sections of the spinning nozzle and/or the yarn. At least one physical parameter of the yarn is monitored by a sensor system wherein, based on a measured value supplied by the sensor system correlated with the parameter, it is determined whether and/or how much additive was applied.

Claims

1. A method to operate an air jet spinning machine having a spinning unit with a spinning nozzle for manufacturing a yarn, comprising: feeding a fiber strand to the spinning nozzle through an inlet during operation of the spinning unit; imparting a twist to the fiber strand inside a vortex chamber of the spinning nozzle by means of a swirled air current so that a yarn is formed from the fiber strand that leaves the spinning nozzle through an outlet; with an additive dispenser, feeding an additive to a location either within the spinning nozzle or upstream of the spinning nozzle while the air jet spinning machine is operating, the additive applied to any combination of the fiber strand, the yarn, or on sections of the spinning nozzle; monitoring a physical parameter of the yarn leaving the outlet with a sensor system; and based on a measured value of the sensor system correlated to the physical parameter, determining if or how much of the additive was applied to the fiber strand or the yarn.

2. The method according to claim 1, wherein manufacturing of the yarn is interrupted by means of a control unit when the sensor system detects that the supplied additive deviates qualitatively or quantitatively from a target value.

3. The method according to claim 1, wherein the sensor system comprises an optical sensor used to monitor a qualitative aspect of the yarn resulting from the additive supply based on the values measured by the optical sensor.

4. The method according to claim 1, wherein the sensor system comprises a capacitive sensor used to monitor a quantitative aspect of the yarn resulting from the additive supply based on the values measured by the capacitive sensor.

5. The method according to claim 4, wherein the additive dispenser supplies the additive in a pulse-like fashion, the quantitative monitoring of the additive supply taking place by evaluating brief mass fluctuations of the yarn detected by the capacitive sensor.

6. The method according to claim 1, wherein the additive dispenser is configured to supply a volumetric flow of the supplied additive is between 0.001 mL/min and 7.0 mL/min, or a mass flow of the supplied additive is between 0.001 g/min and 7.0 g/min.

7. The method according to claim 1, wherein the additive dispenser is configured to supply a volumetric flow of the supplied additive between 0.001 mL/min and 1.5 mL/min during normal operation of the spinning unit, and the volumetric flow of the supplied additive is increased to between 2.0 mL/min and 7.0 mL/min during a cleaning operation of the spinning unit.

8. The method according to claim 1, wherein the additive dispenser is configured to supply a mass flow of the supplied additive between 0.001 g/min and 1.5 g/min during normal operation of the spinning unit, and the mass flow of the supplied additive is increased to between 2.0 g/min and 7.0 g/min during a cleaning operation of the spinning unit.

9. The method according to claim 1, wherein the sensor system is connected to a control unit of the air jet spinning machine and is additionally configured to monitor whether thickness or mass of the yarn lies within predefined limits, the control unit configured to interrupt manufacturing of the yarn upon the predefined limits being not reached or exceeded.

10. The method according to claim 9, wherein a mass flow or volumetric flow of the additive supplied by the additive dispenser during a cleaning operation of the spinning unit is higher than during normal operation, wherein the predefined limits of yarn thickness or mass have different values during the cleaning operation than during normal operation.

11. An air jet spinning machine, comprising: a spinning unit equipped with a spinning nozzle to manufacture yarn from a fiber strand supplied to the spinning nozzle, wherein the spinning nozzle further comprises: an inlet for the fiber strand; a vortex chamber; a yarn forming element protruding into the vortex chamber; an outlet for the yarn generated inside the vortex chamber; 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 and applied on any combination of the fiber strand, sections of the spinning nozzle, or the yarn; a sensor system disposed so as to monitor at least one physical parameter of the yarn leaving the outlet; a control unit allocated to the spinning unit and in communication with the sensor system, the control configured to determine whether or how much additive was applied on the fiber strand or the yarn based on at least one measured value supplied by the sensor system that correlates with the physical parameter.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The following embodiments describe further advantages of the invention, which show in each case schematically:

(2) FIG. 1 A side view of a spinning unit of an air jet spinning machine according to the invention;

(3) FIG. 2 a partially cut section of a spinning unit of an air jet spinning machine according to the invention; and

(4) FIG. 3 various yarn sections.

DETAILED DESCRIPTION

(5) 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.

(6) FIG. 1 shows a section of a spinning unit of an air jet spinning machine according to the invention (although, needless to say, the air jet spinning machine can consist of multiple spinning units arranged preferably next to one another). If necessary, the air jet spinning machine can comprise a drafting system with several drafting system rollers 13, supplied with a fiber strand 3 in form of a doubled drawing frame sliver, for example (for better clarity. only one of the drafting system rollers 13 is given a reference sign). Furthermore, the spinning unit comprises a spinning nozzle 2 with a vortex chamber 5 lying inside (see FIG. 2), in which the fiber strand 3 or at least a portion of the fibers of the fiber strand 3 is imparted a twist after passing an inlet 4 of the spinning nozzle 2 (the precise function of the spinning unit is described in more detail below).

(7) In addition, the air jet spinning machine can encompass a draw-off roller pair 24 arranged downstream from the spinning nozzle 2 and a winding device 1 downstream from the draw off roller pair 24 for spooling the yarn 6 that leaves the spinning nozzle 2 on a tube. Likewise, a yarn carry-off unit 12 (driven pneumatically, for example) can also be provided so yarn sections can be carried off during a cleaning cut in which a yarn error is cut out from the yarn 6. The spinning unit must not necessarily have a drafting system. The draw off roller pair 24 or the yarn carry-off unit 12 are not absolutely necessary either.

(8) The spinning unit shown works generally according to an air jet spinning method: To form the yarn 6, the fiber strand 3 is guided in a stipulated transportation direction T to a fiber guiding element 23 shown in FIG. 2, which guides it to the vortex chamber 5 of the spinning nozzle 2 through the opening formed by the above-mentioned inlet 4. There, a twist is imparted to it, i.e. at least one portion of the free fiber ends 10 of the fiber strand 3 (cf. FIG. 4) is snatched by a swirled air current generated accordingly by air nozzles 19 arranged in a vortex chamber wall arranged around the vortex chamber 5 (the air nozzles 19 are supplied with compressed air, preferably via an air supply pipe 18, that ends in an air supply chamber 17 connected to the air nozzles 19). Here, at least some of the fibers are pulled out of the fiber strand 3 and wound around the tip of a yarn forming element 21 protruding into the vortex chamber 5. Owing to the fact that the fiber strand 3 is drawn out of the vortex chamber 5 through an inlet opening of the yarn forming element 21 via a draw-off channel 20 arranged within the yarn forming element 21 and finally out of the spinning nozzle 2 through an outlet 7, the free fiber ends 10 are also finally pulled towards the inlet opening and in the process twist around as so-called wrap fibers around the centrally running core fibersresulting in a yarn 6 having the desired twist. The compressed air introduced through the air nozzles 19 finally comes out of the spinning nozzle 2 through the draw-off channel 20 and a possibly present air outlet 25, which can be connected to a negative pressure source if necessary.

(9) Generally speaking, it should be clarified here that the manufactured yarn 6 can be basically any fiber strand 3 characterized by the fact that an outer portion of the fibers (the so-called wrap fibers) twists around an inner, preferably untwisted or if necessary twisted portion of the fibers in order to impart the yarn 6 with the desired strength.

(10) Furthermore, an additive supply 8 is allocated to the spinning unit that encompasses one or several additive deposits 15 and one or several, preferably at least partially flexible, additive supply lines 14 through which the corresponding additive deposit 15 is fluidically connected to an additive dispenser 22 arranged in the area of the yarn guiding element 23 or inside the spinning nozzle 2 (with regard to possible additives 9, please consult the description given so far).

(11) Basically, the additive 9 can be dispensed in another spot. While FIG. 2 shows an embodiment, in which the additive dispenser 22 is located in the area of the inlet 4 of the spinning nozzle 2 (so that the additive 9 can be applied on the fiber strand 3), the additive 9 can be likewise added through the compressed air introduced by the air nozzles 19. In this case, the dispensing of the additive 9 is done, for example, through the air supply pipe 18 or the above-mentioned air supply chamber 17, which extends, for example, annularly around the wall delimiting the vortex chamber 5 and through which the air nozzles 19 are supplied with compressed air. Finally, it is just as conceivable to introduce the additive 9 through the draw-off channel 20.

(12) So the additive 9 can be delivered precisely and also in a very reproducible way through the additive dispenser 22 and, in addition, so the dispensed volumetric or mass flow of the additive 9 can be adapted to the respective conditions, the additive supply 8 also comprises at least one dosing unit 16, preferably integrated into the corresponding additive supply line 14, so it can be perfused by the additive 1.

(13) Finally, FIG. 3 shows three yarn sections purely schematically. As shown in FIG. 3a), the yarn 6 manufactured during normal operation without the addition of additive is generally characterized by a certain hairiness, i.e. a part of the free fiber ends 10 and loops stick out. On the other hand, if the fiber strand 3 or yarn 6 is moistened with additive 9, then at least some of these fiber ends 10 attach to the remaining yarn body (see FIG. 3b)), so that the addition of the additive can be detected with the help of an optical sensor (shown in FIG. 1), since there is less hairiness when additive is added than when it is not added. Therefore, by means of the optical sensor, the quantitative monitoring of the addition of additive is possible during normal and/or cleaning operation (i.e. to check whether an additive 9 was added or not). In this case, the measured variable could be the absorption or reflection of the light emitted by the sensor to the yarn 6. Likewise, the shadow of the yarn 6, caused by the corresponding incident light through the yarn 6, can also be monitored.

(14) Similarly, the mass of the yarns 6 can increase by adding additive, so it could also be detected and also quantitatively monitored by a capacitive sensor of the sensor system 11. Here, the capacitive sensor detects either the intrinsic change in the yarn mass (i.e. the change in the overall mass consisting of the mass of the fiber material of the yarn 6 and the mass of the applied additive 9). Likewise, the capacitive sensor could be designed to detect only the mass of the additive 9 (which can be water, for example). Finally, it is naturally also possible to detect just changes in the monitored parameter(s) instead of absolute values.

(15) To conclude, FIG. 3c) shows schematically that the additive 9 can also be provided in form of beads in case the additive 9 is added in pulses. In this case, too, a qualitative and/or quantitative monitoring of the addition of additive (as described so far) would be possible, in which case the monitoring could conceivably take place during normal operation and especially also during the cleaning operation.

(16) The present invention is not restricted to the embodiments shown and described. Modifications within the framework of the invention are just as possible as any combination of the characteristics described, even if they are shown and described in different parts of the description or claims or in different embodiments.