CN113755976B - Yarn splicing method for open-end rotor spinning machine and open-end rotor spinning machine - Google Patents

Abstract

The invention relates to a method for splicing yarns for an open-end rotor spinning machine and an open-end rotor spinning machine, wherein the open-end rotor spinning machine (1) is operated according to a so-called 'joint spinning' method, and stations (2) of the open-end rotor spinning machine (1) are respectively provided with a spinning rotor (8) which can be driven to rotate at a high speed in a rotor shell (18) capable of bearing negative pressure, a fiber sliver opening roller (28) which can be driven and a fiber sliver feeding roller (11) which can be driven by a single motor. In order to ensure that all connections of the open-end rotor spinning machine have a defined structure even after a power failure in the subsequent 'common spinning-in', the feeding speed (45) of the sliver feeding drum is first continuously reduced and then temporarily increased again to produce a supplementary fiber feed into the spinning rotor when a power failure occurs, and the sliver feeding drum is then abruptly stopped, so that a purposeful fiber breakage occurs after the point of supplementary fiber feed, and the broken fibers are removed by the air flow.

Description

Method for splicing yarns in an open-end rotor spinning machine and open-end rotor spinning machine

Technical Field

The invention relates to a method for splicing yarns in an open-end rotor spinning device for stations of an open-end rotor spinning machine according to the so-called "joint spinning-in" method, and to an open-end rotor spinning device.

Background

Various embodiments of open-end rotor spinning machines are known and are described explicitly in the patent literature in many applications. In this case, the various open-end rotor spinning machines usually differ not only in their station design but also in the manner of operation or the operation of their open-end rotor spinning devices. In particular, various methods which differ in part significantly are known in connection with the re-joining of a large number of stations after a power failure.

For example, DE19917968a1 discloses an open-end rotor spinning machine, the large number of work stations of which are supplied by one or more operating assemblies, so-called piecing carriages. Such a collecting trolley is moved as required, for example after a spinning interruption caused by a yarn break, to the relevant station, is brought into position there and the free-end rotor spinning device of the station is again collected. However, in such open-end rotor spinning machines, if a spinning interruption occurs simultaneously at all the stations of the open-end rotor spinning machine, for example because of a power outage, a considerable time is required before the yarn is again spliced at all the stations of the open-end rotor spinning machine. That is to say, even when a plurality of such piecing carriages are operated simultaneously, a considerable time always remains before all the workstations of the open-end rotor spinning machine are again ready for operation. Furthermore, an open-end rotor spinning machine is known, for example, from DE10139075a1, which has the described self-sufficient stations. Such autarkic stations are designed such that they automatically re-join the yarn after the spinning interruption without external assistance. However, a disadvantage of such a self-sufficient station is that its energy requirement during the piecing process is relatively high. That is to say that each of the autarkic stations has a relatively high suction air requirement during the piecing process, with the result that, after a power failure, it is always possible to simultaneously re-piece only a limited number of stations, for example ten of them. Even in the open-end rotor spinning machine according to DE10139075a1, therefore, a relatively long time always remains before a large number of workstations of the spinning machine which produces the cross-wound bobbins are ready for operation again.

In particular in countries with frequent blackouts, open-end rotor spinning machines with workstations operating as described in DE19917968a1 and open-end rotor spinning machines with self-sufficient workstations as described in DE10139075a1 therefore generally have relatively long downtimes and therefore relatively moderate efficiencies.

In areas where frequent consideration is given to power failure, therefore, open-end rotor spinning machines are usually used which operate in the so-called "spinning-in-place" method. In the "common piecing" method, also called batch piecing, the rotor spinning devices of all the stations of the piecing open-end rotor spinning machine are simultaneously renewed after a power failure.

Open-end rotor spinning machines which operate according to the "joint-spinning" method known for a long time are described relatively clearly, for example, in DE3635510a 1.

In these known open-end rotor spinning machines, the workstations, as is also conventional, in particular each have an open-end rotor spinning device for processing the yarn, a yarn take-off mechanism arranged downstream and a winding device for producing a cross-wound bobbin. The open-end rotor spinning device comprises a spinning rotor rotating at high speed in a rotor housing capable of bearing negative pressure, a fiber sliver opening roller rotatably mounted and a fiber sliver feeding roller. The spinning rotor and the sliver opening roller are driven by a tangential belt running around the machine length, and the sliver feeding roller is driven by a drive shaft running along the machine length, which is acted upon by a drive device arranged on the machine end side.

In these known open-end rotor spinning machines, the yarn production of the workstations is always terminated even in the event of a power failure, namely, on the one hand, the supply of the fibre sliver to the drum is stopped and thus interrupted, and on the other hand, the twisted yarn ends remaining in the respective draw-off tube regions of the open-end rotor spinning devices of the workstations are taken care of by controlled braking of the winding bobbins.

In this way, it is ensured that, when the open-end rotor spinning machine is subsequently restarted, i.e. when power is again available, all the workstations of the open-end rotor spinning machine can be put into operation again at the same time. During such a restart, the draw-off mechanisms of the stations serve, on the one hand, to simultaneously withdraw all the thread ends that are in place in the draw-off tube and, on the other hand, to start the fibre supply at all the stations at the same time. The yarn that has reapplied at this time is then drawn off by the drawing mechanism that has just run in the drawing direction and wound onto a cross-wound bobbin in the winding device.

This means in practice that open-end rotor spinning machines which operate according to the "common-spinning" method are usually much quicker to prepare for operation after a power failure than open-end rotor spinning machines whose workstations have to be pieced again only one by one after a power failure, but these known open-end rotor spinning machines which operate according to the "common-spinning" method have the disadvantage that the piecing which occurs does not always meet the high-quality standards. That is, the thread end which remains in the draw tube after a stoppage is usually very different not only in terms of length, but also in terms of thickness, with the result that it is not uncommon for the joint which is reproduced after, for example, a power failure to also be very different or to break again immediately.

Disclosure of Invention

The invention relates to a method for piecing together a spinning device of a workstation of an open-end rotor spinning machine according to the so-called "joint spinning-in" method, wherein the workstations of the open-end rotor spinning machine each have a drivable spinning rotor rotating at high speed in a rotor housing which can be subjected to a negative pressure, a drivable sliver opening roller and a sliver feed roller drivable by a separate motor. The open-end rotor spinning machine is stopped when a power failure occurs, so that the thread end required for the renewed joining remains in the drawtube area of the open-end rotor spinning device of the workstation. After the power is cut off, the open-end rotor spinning devices of all the stations of the open-end rotor spinning machine are simultaneously connected again. The invention also relates to an open-end rotor spinning device.

In view of the above-described type of open-end rotor spinning machine, the invention is based on the object of developing a method in connection with open-end rotor spinning machines which operate according to the "joint-spinning" method, which ensures that all connections of a large number of stations of the open-end rotor spinning machine always have a defined structure even when all stations of the open-end rotor spinning machine are restarted, for example, after a power failure.

According to the invention, the object is achieved in that, in the event of a power failure, the feed speed of the sliver feed drum is first continuously reduced, the feed speed of the sliver feed drum is then temporarily increased again to produce a supplementary fiber feed into the spinning rotor, and the sliver feed drum is then abruptly stopped, so that a targeted fiber breakage occurs after the supplementary fiber feed point, wherein the broken fibers are removed by the air flow.

The method according to the invention has the advantage, in particular, that a defined breaking point is produced by temporarily increasing the amount of fiber to be fed into the spinning rotor and then abruptly stopping the fiber supply, thereby ensuring that the broken thread ends at all stations of the open-end rotor spinning machine have an approximately identical appearance. This means that the thread ends which occur during the splicing at the subsequent stations are used, which are all very similar not only with respect to their thickness, but also with respect to their length. The joint formed with such an optimized thread end is correspondingly likewise almost identical and has good quality standards.

In an advantageous embodiment, the kinetic energy of the spinning rotor drive, which is moved by inertia (spinning), is used to support the supply of the sliver feed drum drive when the power supply is switched off. This means that, although the normal power supply to the open-end rotor spinning machine is interrupted, the inertial rotor drive supplies so much electrical energy that the drive for the sliver feeding drum can be temporarily accelerated, with the result that a temporary increase in the amount of fiber fed into the inertial spinning rotor occurs. The excess fibre that is present at this time is removed by the dirt extraction device of the textile machine.

In a further advantageous embodiment, provision is made for the sliver-feeding rollers to be each stopped when the feeding speed of the sliver-feeding rollers has reached a predetermined target value. Preferably, the sliver feed drum is rotated in the opposite direction after a sudden stop. Thereby, re-falling of some fibers can be prevented. The method steps described above ensure that all joints formed simultaneously always have the specified standard.

In an advantageous embodiment, provision is also made for excess loose fibres, which occur in particular after the fibre breakage, to be sucked away by the dirt suction device at the latest when the open-end rotor spinning machine is restarted. That is to say, when the thread end held in the draw tube is reconnected, it is ensured that in the region of the spinning rotor there is no longer a fibre residue which could adversely affect the appearance or stability of the new splice.

The object is also achieved by an open-end rotor spinning machine having a control device and an open-end rotor spinning device at a working position. The stations of the open-end rotor spinning machine are respectively provided with a spinning rotor which can be driven to rotate at a high speed in a rotor shell capable of bearing negative pressure, a fiber sliver opening roller which can be driven, and a fiber sliver feeding roller which can be driven by a single motor. The control device stops the open-end rotor spinning machine when power failure occurs, so that the yarn end required for yarn splicing again is left in the yarn drawing pipe area of the open-end rotor spinning machine of the station. The control device controls the open-end rotor spinning machine after power failure in such a way that the open-end rotor spinning devices of all stations of the open-end rotor spinning machine are simultaneously re-connected.

According to the invention, the control device controls the sliver feeding roller in the event of a power failure in such a way that the feeding speed of the sliver feeding roller is first continuously reduced, the feeding speed of the sliver feeding roller is then temporarily increased again to produce a supplementary fiber feed into the spinning rotor, and the sliver feeding roller is then abruptly stopped, so that a targeted fiber breakage occurs after the supplementary fiber feeding point, wherein the broken fibers are removed pneumatically.

The starting moment of the supplementary fiber feed can be adjusted by means of the control device. The amount of supplementary fibre feed can also be adjusted by means of the control device. For this purpose, the control device can preferably set a target value for the feed speed of the sliver feed drum after the speed increase thereof.

Drawings

Further details of the invention can be taken from the following examples, which are illustrated in connection with the accompanying drawings, in which:

FIG. 1A shows in a front view a first embodiment of an open-end rotor spinning machine with a plurality of working stations which are located between machine-end frames and whose open-end rotor spinning devices operate according to the "joint spinning" method,

FIG. 1B shows a comparable embodiment of an open-end rotor spinning machine in a front view, with a central frame arranged in the center of the spinning machine and stations arranged on the left and right sides of the central frame, which stations also operate according to the "common-spinning" method,

FIGS. 2A and 2B show in perspective views, respectively, an open-end rotor spinning device which is used in a workstation of an open-end rotor spinning machine and which operates in the "common-spinning-in" method, and

fig. 3 shows a graph showing the course of the feeding speed of the sliver feeding drum after power failure.

List of reference numerals

1 open-end rotor spinning machine

2 station

3 Central frame

4 section(s)

5 free end rotor spinning device

6 winding device

7 spinning can

8 spinning rotor

9 Cross-wound bobbin

10 air pressure device

11 fiber sliver feeding roller

12 yarn guide rod

13 thread guide transmission mechanism

14 yarn guide driving mechanism

15 winding shaft driving mechanism

16 winding shaft

17 winding shaft transmission mechanism

18 revolving cup shell

19 negative pressure device

20 tangential belt transmission mechanism

21 tangential belt transmission mechanism

22 opening roller shell

23 tangential belt

25 connecting pipe

26 tangential belt

27 Filter device

28 opening roller

29 control device

30 machine frame

31 revolving cup shaft

32 direct support mechanism

33 fiber sliver opening device

34 pivot axis

35 brake element

36 air inlet

37 air outlet

38 dirt pumping and discharging pipe

39 support shaft

40 machine frame

41 cover member

42 revolving cup shaft

43 target value for feed with supplemental fiber

44 start of supplemental feed

45 feed rate

46 moment of power failure

47 target value for fiber feed without make-up

Detailed Description

Fig. 1A schematically shows a first exemplary embodiment of an open-end rotor spinning machine 1, which has a plurality of stations 2, in which, for example, a "common spinning-in" method is used in the event of a power failure. As shown, the open-end rotor spinning machine 1 has two machine-side frames 30 and 40, in which at least some of the drives for the working parts of the stations 2 are arranged in each case, similarly to fig. 1B. The workstations 2 arranged between the racks 30 and 40 are combined here to form so-called segments 4, which are generally installation units, wherein the individual segments 4 each have a plurality of workstations 2 on both sides. Typically, twelve stations 2 are arranged side by side on each side of the section 4 (e.g. interconnected by connectors or joined to the racks 30, 40). The frame 40 is also provided with a control device 29, which controls the production process of the open-end rotor spinning machine 1 and by means of which an operator can set parameters.

Fig. 1B shows an alternative embodiment of the open-end rotor spinning machine 1. The working position 2 of the comparable open-end rotor spinning machine 1 is operated in the "common-spinning" method after a power failure. As shown, the open-end rotor spinning machine 1 also has a plurality of sections 4, each equipped with 24 workstations 2. However, the open-end rotor spinning machine 1 has a central frame 3 arranged substantially centrally between a large number of segments 4.

The workstations 2 of the open-end rotor spinning machine 1 are each, as is usual, equipped with an open-end rotor spinning device 5 equipped with a spinning rotor 8, an opening roller 10 and a fiber sliver feed drum 11, and with a winding device 6 equipped with a creel, a thread traversing device and a bobbin drive roller, which are not shown in detail in fig. 1A and 1B for the sake of a better overview. In the case of the open-end rotor spinning device 5, a fiber sliver stored in a spinning can 7 is spun as usual into a yarn, which is then wound on a winding device 6 into a cross-wound bobbin 9.

The various working components of the open-end rotor spinning device 5 and of the winding device 6 are now acted upon either by means of so-called group drives and/or by separate drives.

By means of such a group drive, for example a yarn traversing of the winding device 6 is operated, where the machine-side (not shown) yarn guides are engaged to a yarn guide gear 13 and to a yarn guide drive 14, respectively, by means of a yarn guide rod 12 along the machine length. The thread guide drive 13 and the associated thread guide drive 14 are arranged here as shown in fig. 1B on the central frame 3, which is arranged approximately centrally between the work stations 2. A winding shaft drive 15 and a winding shaft gear 17 are also provided in the central frame 3 for a rotatably mounted winding shaft 16, which frictionally drives the cross-wound bobbin 9 via the associated winding roller.

The central frame 3 also has at least one device 19 for generating the negative pressure required during the spinning process and a filter device 27 for cleaning the air contaminants present during the spinning process. In the central housing 3, there are also arranged drive means 20 and 21 for a tangential belt 23 or 26 acting on the spinning rotor 8 or the opening roller 28 of the open-end rotor spinning device 5 and a control device 29 positioned. The central frame 3 may also have a connection pipe 25 by means of which the open-end rotor spinning machine 1 may be connected, for example, to an external air pressure source or to the air conditioning of the spinning mill itself.

The large number of segments 4 arranged on both sides of the central frame 3 of the open-end rotor spinning machine 1 are equipped here, as is known and therefore not shown in the interest of a better overview, with various continuous supply and discharge channels, for example air channels for spinning air suction, electronics channels for bus connection of the control device 29 and/or cable channels for yarn monitoring devices. In addition, various drives are installed in the section 4, by means of which the working parts of the station 2 can be acted upon. Such drive units are, as already mentioned, for example, the thread guide bar 12, the winding shaft 16 and the thread unwinding shaft. Tangential belts 23, 26 for driving the spinning rotor 8 or the opening roller 28 also pass through the section 4. Furthermore, a continuous drive shaft for the sliver-feeding drum 11 or a separate drive which can be controlled as required is provided in the section 4.

Fig. 2A and 2B each show, in a perspective view, an open-end rotor spinning device 5 of a semiautomatic open-end rotor spinning machine 1, for example. As described above, the open-end rotor spinning machine 1 has a plurality of work stations 2, each of which is equipped with an open-end rotor spinning device 5 and a winding device 6, not shown in fig. 2A and 2B.

The open-end rotor spinning devices 5 are in this case, as is known, each equipped with a rotor housing 18 which can be subjected to an underpressure, in which the spinning rotor 8 rotates at high speed during the spinning process. Furthermore, the open-end rotor spinning device 5 has an associated opening roller housing 22, in which an opening roller 28 is rotatably mounted. The opening roller 28 combs out the sliver of fiber stored in the spinning sliver can 7 and fed through the sliver feed drum during the spinning operation, wherein the single fibers combed out by the opening roller 28 are conveyed by an air flow through a so-called fiber guide channel to the rotor housing 18 subjected to negative pressure and are spun there into yarn by the rotating spinning rotor 8.

The free-end rotor spinning devices 5 shown in the embodiments of fig. 2A and 2B are also each mounted in a manner pivotable to a limited extent by means of a bearing mechanism, for example a bearing shaft 39 along the machine length.

The spinning rotor 8 is mounted rotatably with its rotor shaft 31, for example, in a direct bearing 32 and is driven by a revolving tangential belt 23 running along the machine length and abutting the rotor shaft 31.

The rotor housing 18, which is subjected to the spinning underpressure, is connected, as described above, via a fibre guide channel to a fibre sliver opening device, generally designated 33, in which the cup body of the spinning rotor 8 rotates at high speed during the spinning process and which can be closed by a cover 41. The direct support 32 and the rotor housing 18 form a rotor shaft support 42, which is connected to the opening roller housing 22 of the fiber sliver opening device 33 via a pivot axis 34. In the operating position (in which the axis of rotation of the opening roller 28 and the axis of rotation of the sliver feed drum 11 are arranged orthogonally to the axis of rotation of the spinning rotor 8), the roller bearing 42 is positioned in such a way that the rotor shaft 31 bears against the revolving tangential belt 23 along the length of the machine from below. When the free-end rotor spinning device 5 is open, the rotor shaft support 42 is in the rest position, in which the stop member 35 abuts the rotor shaft 31, which is now in a position spaced from the tangential belt 23 along the length of the machine.

The opening roller 28 and the fiber sliver feeding drum 11 are rotatably mounted in an opening roller housing 22, preferably made of aluminum alloy, wherein the opening roller 28 is drivable by means of a tangential belt 26 along the length of the machine, while the fiber sliver feeding drum 11 is connected to a long drive shaft or is acted upon by a separate drive means, preferably a stepping motor.

The opening roller housing 22, which is in pneumatic communication with the rotor housing 18, which can be subjected to underpressure, via a fiber guide channel, also has a pneumatic device 10, which serves in particular for the defined removal of dirt particles and fiber residues during the spinning process. The pneumatic device 10 has an air inlet 36, through which ambient air flows into the opening roller housing 22 during the spinning process, said ambient air forming an air flow guide for the carded, well-defined filaments in the region of the opening roller housing 22. On the side of the air press 10 opposite the air inlet 36, there is an air suction opening 37 which is part of a dirt extraction duct 38 connected in a pressure-tight manner to the trapway along the length of the machine. The trapway can be subjected to airflow, for example, by a negative pressure device 19 located within the central housing 3.

The method has the following functions:

if a power outage occurs in the spinning mill, which results in the working members of all stations 2 of the free-end rotor spinning machine 1 being unpowered, the working members start to jog to a stop. Up to now, this also concerns an open-end rotor spinning machine 1 which operates according to the so-called "common-spinning" method during the re-piecing of its various stations 2.

However, according to the invention, the kinetic energy of the central drive, preferably the inertial spinning rotor drive 20, is preferably used to ensure a temporary energy supply for controlling all the associated drives, in particular the sliver feed drum 11, until the machine is stopped. In principle, it is also possible for the energy required after a power failure to be provided by a battery or an additional generator. According to the invention, the sliver feed rollers 11 are driven temporarily, so that the value of the amount of fiber to be fed into the opening roller housing 22 and thus into the spinning rotor 8, respectively, by means of the sliver feed rollers 11, is increased and thus a supplementary fiber feed is produced, as required, which results in a theoretical breaking point. That is, the breaking of the fibers at the theoretical breaking point ensures that the thread end to be held in the draw tube after the power failure is optimized. That is, the thread ends required for the re-joining in accordance with the "common-end" method at the working position 2 of the open-end rotor spinning machine 1 are almost the same in terms of length and thickness.

As shown in the diagram of fig. 3, the kinetic energy of the spinning rotor drive 20, which is moved by inertia, is used to influence the feeding speed of the sliver feeding roller 11, which is indicated in the diagram by the reference numeral 45, as required. That is, the feeding speed 45 of the sliver feeding roller 11 is first continuously decreased as shown from a point 46 indicating the moment of power-off. During the continuous reduction of the feed rate 45, the target value 47 of the feed rate 45 is reached at a certain point in time, at which time the operation can no longer be maintained. When the target value 47 is reached, the kinetic energy of the spinning rotor drive is then used to increase the feed speed 45 of the sliver feed drum 11 and thus the fiber feed to the spinning rotor 8, also briefly in one step. The starting point of the predeterminable temporary increase in the fiber feed, which is designated by reference numeral 44, can be set in the control device 29 according to the software, as is the desired fiber feed. The start time 44 is, for example, 150 ms before the target value 43, at which the fiber web feed drum 11 is suddenly stopped and the fiber feed is adjusted accordingly.

The temporary increase in the fibre feed combined with the fact that the spinning rotor becomes slower while reducing the effective centrifugal force results in a defined breaking of the fibres.

Since the "theoretical breaking point" occurs simultaneously at all the stations 2, the effect is also almost identical. That is, the thread ends to be held in the draw-off tube are very similar not only in their length but also in their thickness, with the result that all the joints produced are perfect when the electricity is cut off and subsequently the yarn is reconnected according to station 2 of the "co-threading" method.

Claims (8)

1. Method for piecing together free-end rotor spinning devices (5) of a plurality of workstations (2) of a free-end rotor spinning machine (1), wherein the workstations (2) of the free-end rotor spinning machine (1) each have a spinning rotor (8) which can be driven, a sliver opening roller (28) which can be driven and a sliver feed roller (11) which can be driven by a separate motor, the spinning rotors (8) rotating at high speed in a rotor housing (18) which can be subjected to a negative pressure, wherein the free-end rotor spinning machine (1) is shut down when a power failure occurs, so that the thread ends required for the rethreading remain in the take-up tube region of the free-end rotor spinning devices (5) of all workstations (2) of the free-end rotor spinning machine (1) after the power failure and the free-end rotor spinning devices (5) of all workstations (2) of the free-end rotor spinning machine (1) are rethreaded together, characterized in that, in the event of a power failure, the feed speed (45) of the sliver feed drum (11) is first continuously reduced, then the feed speed (45) of the sliver feed drum (11) is temporarily increased again to produce a supplementary fiber feed into the spinning rotor (8), and then the sliver feed drum (11) is abruptly stopped, so that a targeted fiber breakage occurs after the point of supplementary fiber feed, wherein the broken fibers are pneumatically excluded.

2. Method according to claim 1, characterized in that the kinetic energy of the inertial spinning rotor drive is used to support the supply of the drive of the sliver feeding roller (11) when de-energized.

3. Method according to any of the preceding claims, characterized in that the sliver feeding drum (11) is abruptly stopped when the feeding speed (45) of the sliver feeding drum (11) reaches a target value (43).

4. Method according to any of the preceding claims, characterized in that the sliver feeding drum (11) is turned back after a sudden stop.

5. Method according to any of the preceding claims, characterized in that excess loose fibre is sucked away at the latest when the open-end rotor spinning machine (1) is restarted.

6. An open-end rotor spinning machine (1), which open-end rotor spinning machine (1) has a control device (29) and an open-end rotor spinning device (5) at stations (2), wherein the stations (2) of the open-end rotor spinning machine (1) each have a spinning rotor (8) which can be driven, a fiber sliver opening roller (28) which can be driven and a fiber sliver feed roller (11) which can be driven by a separate motor, the spinning rotors (8) rotating at high speed in a rotor housing (18) which can be subjected to a negative pressure, wherein the control device (29) stops the open-end rotor spinning machine (1) when a power failure occurs, so that the thread ends required for renewed spinning remain in the spinning tube region of the open-end rotor spinning device (5) of the station (2), wherein the control device (29) controls the open-end rotor spinning machine (1) after the power failure, -that the open-end rotor spinning devices (5) of all stations (2) of the open-end rotor spinning machine (1) are simultaneously re-pieced in turn, characterized in that the control device (29) controls the sliver feeding drum (11) in the event of a power failure such that the feeding speed (45) of the sliver feeding drum (11) is first continuously reduced and then the feeding speed (45) of the sliver feeding drum (11) is temporarily increased again to produce a supplementary fiber feed into the spinning rotor (8), and the sliver feeding drum (11) is then abruptly stopped such that a targeted fiber breakage occurs after the point of supplementary fiber feed, wherein broken fibers are pneumatically excluded.

7. Open-end rotor spinning machine (1) according to claim 6, characterized in that the starting moment (44) of the supplementary fiber feed can be adjusted by means of the control device (29).

8. Open-end rotor spinning machine (1) according to claim 6 or 7, characterized in that the amount of supplementary fiber feed can be adjusted by means of the control device (29).

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