CN109384097B

CN109384097B - Device for removing yarn defects from yarns

Info

Publication number: CN109384097B
Application number: CN201810876498.6A
Authority: CN
Inventors: U·霍尔特; M·伊丁; M·尼科利奇; W-M·鲁
Original assignee: Saurer Germany GmbH and Co KG
Current assignee: Saurer Spinning Solutions GmbH and Co KG
Priority date: 2017-08-04
Filing date: 2018-08-03
Publication date: 2020-06-19
Anticipated expiration: 2038-08-03
Also published as: CH714064A2; DE102017117743A1; JP7085937B2; CH714064B1; JP2019031399A; CN109384097A

Abstract

The invention relates to a device for removing yarn defects from a yarn. The device is used for clearing yarn faults classified according to different yarn fault types, comprises a measuring head for measuring at least one predeterminable yarn parameter, and is suitable for signaling the existence of the yarn faults and the yarn fault types under the condition of different value ranges related to the yarn parameters, and triggers a yarn clearing cutting based on the yarn fault signals, and the yarn faults run to a winding bobbin (3) of a textile machine for manufacturing the winding bobbin by means of the yarn clearing cutting. A memory unit (8) is associated with the device (18), a yarn searching program of a suction nozzle (14) designed for searching yarn heads of the upper yarn is respectively stored in a callable mode for different yarn defect types in the memory unit, and the device (18) is suitable for starting the corresponding yarn searching program according to the yarn defect type indicated by the signaling so as to capture the yarn heads of the upper yarn, which run onto the winding bobbin (3), by means of the suction nozzle (14).

Description

Device for removing yarn defects from yarns

Technical Field

The invention relates to a device for removing yarn defects from a yarn, which are classified according to different types of yarn defects, a textile machine for producing a winding bobbin having such a device, a memory unit for storing at least one yarn seeking program corresponding to the type of yarn defect, and a method for obtaining a yarn end falling on the winding bobbin.

Background

In the textile industry, various types of textile machines for producing wound bobbins have long been popular. Besides the open-end spinning machines, for example, winding machines are used in large numbers.

At the winding station, the spinning bobbin produced on the ring spinning machine and containing only relatively little yarn material is rewound into a large package wound bobbin. The yarn is monitored during rewinding for yarn faults which are cut and replaced by a spliced yarn which is almost the same as the yarn.

For this reason, not only the upper thread withdrawn from the winding bobbin but also the lower thread from the unwinding bobbin are always required on the winding unit of the winding machine.

Usually, the yarn joining robot of the workstation itself is activated by the winding unit computer of the relevant winding unit in the case of a controlled clearing cut.

That is to say, firstly, the suction nozzle receives suction air on the surface of the winding bobbin which rotates slowly counter to the winding direction. After catching the upper thread end, the suction nozzle is pivoted to a thread insertion position in which the suction nozzle mouth is in place below the thread splicing device. Subsequently, the nipper bobbin in the lower initial position is pivoted into the upper working position and simultaneously carries off the lower yarn drawn off from the unwinding bobbin.

A large number of workstations are each provided with a workstation computer which is itself connected to a central control unit of the textile machine.

In general, the response sensitivity of the clearer can be set at a central control unit of the textile machine, i.e. whether the inhomogeneities are classified as yarn defects or not can be set centrally. Yarn faults refer to common and rare yarn faults, which are also referred to herein as yarn faults and include neps in addition to slubs and details. If a non-uniformity is found and classified as a yarn defect, because a predetermined tolerance limit is exceeded, the clearer triggers a clearer cut.

DE19640184a1 discloses, for example, that the yarn is drawn off from an unwinding bobbin, such as a textile bobbin, and wound into a winding bobbin, such as a cross-wound bobbin, by means of a winding device. The running thread is guided through the measuring head and the cutting-off mechanism of the clearer. The clearer measures a measurement representative of the yarn quality. When the clearer finds an intolerable defect, i.e. when the measured variable differs from a predetermined value, a so-called clearer cut is triggered by the clearer, i.e. a cutting mechanism is activated to remove the defective portion of the yarn. After the yarn is cut, the yarn end with the defective portion falls onto the winding bobbin. The yarn ends are caught by a pivotable suction nozzle and the defective yarn sections are sucked away. The upper thread from the winding bobbin is inserted into the splicing device and the defective thread section is cut off. Accordingly, the discharge yarn from the unwinding bobbin is inserted into the yarn splicing device by means of a pivotable yarn clamping tube and forms a yarn joint.

EP0531894a1 discloses a method and a device for sorting and clearing yarns, whereby yarn defects are imaged two-dimensionally in a defined yarn length on the basis of deviations from the theoretical value of the yarn thickness. The yarn defects are detected by means of a measuring device in relation to the diameter and the length thereof, are subsequently evaluated and classified according to the classification region of the defect matrix. For this purpose, the frequency of occurrence of yarn defects meeting the respective classification criterion is known quantitatively in the classification region and is displayed in two dimensions. By means of the display on the screen, the occurrence of the defect frequency can be perceived in dependence on the number displayed in each classification area.

However, the known methods and devices have in common that, although different types of thread defects are identified and ascertained, and a thread-seeking program for the suction nozzle for catching the upper thread is present and operated, it is also known in connection with the upper thread catching that the distance from the suction nozzle to the winding bobbin is optimized when the upper thread catching is unsuccessful and the underpressure prevailing for catching the upper thread is adapted continuously over the entire winding path, but the thread-seeking program is carried out uniformly for all the found thread defects.

Disclosure of Invention

A first aspect of the invention therefore relates to a device for clearing yarn defects from a yarn, which are classified according to different types of yarn defects, having a measuring head for measuring at least one predeterminable yarn parameter and being adapted to signal the presence of a yarn defect and a type of yarn defect in the event of a difference from a value range associated with the yarn parameter and to trigger a clearing cut based on a yarn defect signal, by means of which the yarn defect falls onto a winding bobbin of a textile machine which produces the winding bobbin.

The proposed device is characterized in that a memory unit is associated with the device, in which a yarn search program for a textile machine suction nozzle designed for searching for a yarn end of a yarn on a winding bobbin is stored in a retrievable manner for different types of yarn faults, and the device is suitable for starting the corresponding yarn search program according to the type of yarn fault signaled so as to capture the yarn end of the yarn on the winding bobbin by the suction nozzle.

In this way, an individually adapted yarn search procedure can be performed for one yarn defect type. In an attempt, different yarn seeking parameters for different yarn defect types were determined to improve yarn pick-up. Basically, yarn defect types are divided into slubs, details and neps, where it is also possible within the scope of the invention to subdivide some yarn defect types into further sub-categories.

The yarn-seeking parameters include, for example, the level of the underpressure, the distance of the suction nozzle from the periphery of the winding bobbin for capturing the yarn-feeding head from the winding bobbin and whether and at what time interval the suction nozzle performs a nodding movement when capturing the yarn-feeding. The suction nozzle can also be subjected to a negative pressure continuously or in pulses. In principle, the yarn seeking parameters comprise all parameters relating to the yarn catching on the upper yarn.

For example, it has become clear that in the case of details it is advantageous if the suction nozzle is positioned closer to the circumference of the bobbin at a higher underpressure. Conversely, the nubs can be reliably captured at lower negative pressures even when the suction nozzle is further away, the neps being captured at a further reduced negative pressure, which is perhaps supported by the nodding movement of the suction nozzle.

The yarn search program is stored in the memory unit and is available, so that the yarn search program corresponding to the current yarn defect type can be executed according to the found yarn defect type. That is, if the device for example finds a slub, a so-called clearing cut is triggered in order to clear the yarn defect from the yarn and signals the type of yarn defect. Since a separate thread-seeking program is also stored in the memory unit associated with the device for the type of slub thread defect, this thread-seeking program is selected and executed in order to catch the thread-feeding end falling onto the winding bobbin with the suction nozzle. The yarn search program optimized for slubby differs in at least one parameter from the remaining stored yarn search programs for other yarn defect types.

Due to the yarn seeking procedure, which is individually adjusted for different yarn defect types, the yarn seeking capture rate (rate) is improved, whereby the upper yarn can be captured more quickly overall. The winding process after the clearing cut can thereby be continued more quickly and the efficiency of the textile machine is increased. The optimally set vacuum (in which case the suction nozzle is only supplied with the vacuum required for the acquisition of the current thread end) then also ultimately contributes to the energy consumption of the textile machine.

In a preferred embodiment of the invention, the catch rate for the yarn search for each yarn defect type can be determined and stored, and the yarn search program can be automatically adjusted if the catch rate differs from a limit value.

If for each yarn defect type it is identified and stored how frequently the upper yarn end cannot be caught by the suction nozzle and if a limit value is specified in the storage unit which defines the allowed number of unsuccessful yarn take-up attempts, at least one yarn seeking parameter is changed when the limit value is exceeded. For example, the suction nozzle can be positioned closer to or further away from the bobbin, or the underpressure prevailing in the suction nozzle can be reduced or increased. Instead of a permanently existing underpressure, the suction nozzle can also be subjected to an underpressure in pulses, or the suction nozzle can perform a nodding movement. Depending on the scope of the invention, individual yarn-seeking parameters can be changed or a plurality of yarn-seeking parameters can be changed in combination with one another.

The automatic adjustment of the yarn-seeking program is advantageously carried out individually for the respective work station, for the product group or for the entire textile machine.

The automatic adjustment of the yarn-seeking program (in which at least one yarn-seeking parameter is changed by a difference from the limit value for the yarn-feeding capturing rate) can be selected in such a way that it is carried out, for example, for a certain station. This may be advantageous, for example, when winding a sample bobbin on one of the stations of its spinning machine. However, it may also be advantageous to limit the automatic adjustment to a group of products or a batch if several batches are produced simultaneously on the textile machine or if not all stations are occupied. It is also conceivable that the automatic adjustment of the yarn-seeking program is carried out for the entire textile machine.

The storage unit is preferably formed by a station control device, a central control unit or an external storage unit.

It is possible according to the scope of the invention for the memory unit, in which various yarn-seeking programs are stored and retrievable, to be a component of the position control device or of the central control unit itself. This is advantageous because the devices and structures that are inherently available can be used without the need to add complex new components. But the storage unit may also be an external medium, such as a USB disk or an electronic device, such as a computer, tablet, smart phone, etc., which can be connected to the textile machine or device. This may be, for example, a medium which can be interfaced to the device or textile machine via a suitable interface or can be connected thereto wirelessly.

A second aspect of the invention relates to a textile machine for producing bobbins, comprising a device for removing yarn defects from a yarn, which are classified according to different yarn defect types.

The textile machine for producing wound bobbins is characterized in that at least one device is designed according to one of the embodiments described above.

With such a textile machine, it is possible to continue the winding process interrupted by the found yarn defect and the subsequent clearing cut again more quickly and thus efficiently. The yarn pick-up is improved due to the yarn searching procedure which is individually adjusted for each yarn defect type. The efficiency of the textile machine is generally increased since only a few times are required to successfully catch the thread ends from the winding bobbins. In addition, since in general only a few attempts are made to capture the upper yarn and the level of underpressure is adapted to the current yarn defect type as required, the underpressure consumption is reduced and the overall energy requirement of the textile machine is finally optimized.

A third aspect of the invention relates to a method for capturing a yarn end on a winding bobbin, which falls onto a workstation of a textile machine that produces winding bobbins, by means of a textile machine suction nozzle associated with the winding bobbin, wherein the method has a first step of controlled clearing and cutting after signaling a yarn defect and a corresponding yarn defect type.

The method is characterized in that in a second step a yarn search routine corresponding to the type of yarn defect indicated by the signal is called from the memory unit, and in a third step the dropped yarn end of the upper yarn is captured by means of the suction nozzle according to the called yarn end search routine.

If a separate thread-seeking program is present in the memory unit for different types of thread faults, such as slubs, details or neps, and if a thread fault is detected, a thread-seeking program is signaled, which includes corresponding thread-seeking parameters, for the type of thread fault, and the subsequent capturing of the wound bobbin is carried out according to the thread-seeking program specific to the type of thread fault. Such yarn-seeking parameters include, for example, the distance of the suction nozzle from the winding bobbin or whether the suction nozzle is located in front of the winding bobbin, as in the case of a tap movement, for example, statically or dynamically. The negative pressure applied to the suction nozzle in order to catch the yarn head is reduced, or a permanent or pulsating negative pressure application reduction is carried out under the yarn searching parameters of the yarn searching program.

The practice according to the invention ensures that the upper thread can always be reliably and quickly caught by the suction nozzle after the clearing cut, so that the interrupted winding process can be continued as quickly as possible.

In an advantageous embodiment, the capture rate of the thread end of the upper thread is determined and stored for each type of thread defect, and the thread-seeking program is automatically adjusted if the capture rate differs from a limit value.

The development of the invention allows further optimization of the yarn feed search, since for each yarn defect type it is recorded and stored individually how often the yarn feed cannot be successfully received by the suction nozzle and a limit value is defined in advance, so that if said limit value is exceeded, the corresponding yarn feed program can be automatically adjusted. I.e. for example slubby is found and the suction nozzle is controlled according to the corresponding yarn finding program and the upper yarn is not caught by the suction nozzle, which is found and stored. If, for example, the 10 th recording indicates that a coarse yarn search is not successful and the limit value 10 was previously defined, the coarse yarn search routine is adjusted after the 10 th yarn attempt is successful by changing at least one yarn search parameter. This can relate, for example, to the magnitude of the underpressure present or the distance of the suction nozzle from the winding bobbin. In connection with the invention, such a capture rate is defined, for example, for each clearing cut, each yarn defect type or in connection with a batch.

In particular, the automatic adjustment of the yarn-seeking program is carried out individually for the respective work station, for the product group or for the entire textile machine.

The aforementioned automatic adjustment of the yarn-seeking program can be selected and carried out as desired, i.e. the adjustment is carried out either for each station for one production group, for example a batch, or for the entire textile machine.

Preferably, the storage is performed in the workstation control device, the central control unit or an external storage unit.

Depending on the product construction, the yarn search program can be stored at different locations. This can be, for example, a station control (which is present at each individual station) or a central control unit, which is connected to the individual stations. But an external storage unit is also conceivable, which can be brought into physical or wireless contact with the device itself or with the textile machine.

A fourth aspect of the invention relates to a memory unit for the retrievable storage of at least one yarn seeking program associated with a type of yarn defect for capturing a yarn end of a yarn supply running on a winding bobbin of a textile machine producing the winding bobbin by means of a textile machine nozzle.

The storage unit is characterized in that a yarn search program is provided for carrying out the method according to one of the preceding embodiments.

The storage unit can be designed as part of a cost-effective component, such as a station control or a central control unit. However, the memory unit can also be designed as an external memory unit, for example a usb-disk, a computer or the like, which can be connected to the device or textile machine via an interface or wirelessly. It is essential to the invention that the memory unit is designed such that at least one yarn finding program for a certain yarn defect type is stored in said memory unit and can be called up.

Drawings

Other features and advantages of the invention will be apparent from the following description of the preferred embodiments of the invention, taken in conjunction with the accompanying drawings which set forth the important details of the invention, and from the claims. These features may be implemented in the preferred embodiments of the present invention individually or in any combination of a plurality thereof.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a side view of a winding unit of a winder, and

fig. 2 is a flow chart of a method.

List of reference numerals

1 station

2 spinning bobbin

3 winding bobbin

4 yarn

5 Cross winding bobbin conveying device

6 bobbin and bobbin conveying system

7 conveying disc

8 memory cell

9 cop supply section

10 savings zone

11 transverse conveying section

12 bobbin feedback section

13 unwinding position

14 suction nozzle

15 pincers bobbin

16 yarn splicing device

17 yarn tensioner

18 device

19 winding device

20 bobbin creel

21 pivot axis

22 grooved roller

23 suction channel

24 axes of rotation

25 pivoting drive mechanism

26 winding unit casing

27 suction slot

28 axis of rotation

29 clamp bobbin cover

30 run of yarn

31 line

32 line

33 final position

34 final position

100 method

110 first step

120 second step

130 third step

Detailed Description

Fig. 1 schematically shows a station 1 of an automatic winder in a side view. Such winders usually have a number of identical stations 1, also called winding units, between the end stands of the winder (not shown).

At this winding unit, as is known and therefore not described in detail, the spinning bobbin 2 produced on the ring spinning machine is rewound into a large-package cross-wound bobbin. The spinning bobbin 2 is now an unwinding bobbin from which the yarn 4 is unwound. The cross-wound bobbin forms a winding bobbin 3 on which the yarn 4 is wound.

After the cross-wound bobbins have been produced, they are transported by means of an automatically operating service unit, preferably (not shown), a cross-wound bobbin exchange device to a cross-wound bobbin transport device 5 along the machine length and to a bobbin loading station or the like provided at the machine end.

Such a winding machine additionally has a logistics device in the form of a bobbin and bobbin transport system 6. In the bobbin and bobbin transfer system 6, the spinning bobbins 2 and the empty bobbins circulate on a transfer tray 7.

Furthermore, such automatic winding machines are usually provided (not shown) with a central control unit which is connected via a machine bus to the individual winding unit computers of the individual winding units and to the control of the service unit. The storage unit 8 is constituted by a winding unit computer in this embodiment.

Fig. 1 shows only the cop supply section 9, the positively and negatively drivable accumulator section 10, the transverse transport section 11 to the winding unit and the bobbin return section 12 of the bobbin transport system 6 described above.

The spinning bobbin 2 provided is rewound in the unwinding position 13 (on the winding unit in the region of the transverse transport section 11) to form a large cross-wound package. The individual winding units are then provided, as is known and therefore indicated only, with various devices which ensure that the stations operate as intended. Such as a suction nozzle 14, a nipper bobbin 15 and a yarn splicing device 16.

The yarn splicing device 16 is preferably designed as an air splicer. The air splicer is slightly retracted with respect to the normal yarn direction and is provided with an upper clamp shut-off mechanism and a lower clamp shut-off mechanism.

Such a winding unit is also provided with a thread tensioner 17, the inventive device 18 designed in this example as a clearer, and other devices not shown in detail, such as a waxing device, a thread cutting mechanism, a thread tension sensor, and a thread take-off sensor.

The winding device, generally designated by reference numeral 19, is formed by a creel 20, which is movably mounted about a pivot axis 21 and has a mechanism for rotatably holding a cross-wound bobbin tube.

During the winding process, the cross-wound bobbin rests with its surface against the grooved roller 22 and is driven by the grooved roller 22 by frictional engagement.

As previously mentioned, each winding unit is provided with a suction nozzle 14 and a nipper bobbin 15, which are connected to a suction channel 23 along the length of the machine, respectively, by means of suction air nipples.

The suction nozzle 14 is pivotally mounted about an axis 24. The pivotal movement of the suction nozzle 14 is performed by a pivotal drive mechanism 25 disposed within a winder unit housing 26. The pivot drive mechanism 25 is computer controlled by the winding unit. The suction nozzle 14 has a not shown controllable communication with the suction channel 23 in the region of the axis 24. The suction nozzle 14 has a suction slot 27 for catching or catching a yarn end falling or having fallen onto a cross-wound bobbin. The suction nozzle 14 can be positioned with its suction slit 27 in the cross-wound bobbin sub-area by means of the pivoting drive mechanism 25. The suction slot 27 extends here approximately parallel to the circumference of the cross-wound bobbin. Deviations from parallelism occur, for example, in the case of conical bobbins, as a function of the bobbin shape.

The nipper tube 15 is mounted pivotably about an axis of rotation 28 and additionally has a nipper tube cover 29 at its free end, which allows closing of the nipper tube mouth.

Fig. 1 shows a state of a winding unit in a normal winding process. The suction nozzle 14 is positioned with its suction slot 27 in the cross-wound bobbin region and the suction slot 27 is directed toward the cross-wound bobbin. During the winding process, the diameter of the cross-wound bobbin increases. This changes the distance from the suction slot 27 to the peripheral surface of the crosswound bobbin. To compensate for this change, the suction nozzle 14 is moved about the axis 24 in accordance with the diameter of the cross-wound bobbin. In this way, the distance from the suction slot 27 to the peripheral surface of the crosswound bobbin can be kept within a prescribed range.

The nipper tube 15 is positioned in the lower position during normal winding, i.e. the nipper tube mouth is located below the yarn splicing device 16 and before the run of the yarn 4 as seen from the operator's line of sight.

The process in the clearing cut is in this embodiment computer controlled by the winding unit. However, it is also possible for the control to be effected by other control devices of the textile machine, for example a central control unit or to be initiated by an externally connected control unit.

And starting the clearing and cutting after the yarn defect is found. The lower yarn 30 is generally held in the yarn tensioner 17 while the upper yarn runs onto the surface of the cross-wound bobbin. The type of yarn defect, in this example the details, is also signaled.

As soon as a yarn break is detected by the winding unit, suction air is applied to the suction nozzle 14, at which time the negative pressure level is specified by the selected yarn search program. At the same time, the braking process of the cross-wound bobbin is started, and the braked cross-wound bobbin slowly rotates opposite to the winding direction. Depending on the yarn-seeking procedure, the suction slots 27 of the suction nozzles 14 are located differently far and near on the circumference of the cross-wound bobbin. The thread-seeking program also specifies whether the suction nozzle 14 is continuously held in this position during the catching of the thread or whether the suction nozzle 14 performs a nodding movement (nodding movement) during this time, for example.

If the upper yarn cannot be caught by the suction nozzle 14 or cannot be correctly caught by the suction nozzle 14, the upper yarn is individually measured and stored for the current yarn defect type. A limit value is defined in the winding unit computer, which in this example defines 10 attempts to catch the fault for the details. Once 11 attempts to capture the upper yarn are found to be ineffective, the yarn finding program stored in the winding unit computer is automatically adjusted. That is, the distance from the suction nozzle 14 to the cross-wound bobbin is reduced. The next time the thread is picked up after finding the detail, the suction nozzle 14 is moved to this correct distance from the cross-wound bobbin.

After the suction nozzle 14 has received the upper thread, the suction nozzle 14 is pivoted from its initial position shown in fig. 1 along the broken line 31 to a final position.

When the upper yarn is caught and sent towards the yarn joining device, the lower yarn 30 has been picked up by means of the nipper tube 15. For this purpose, the gripper tube 15 pivots with its gripper tube mouth into the region immediately below the thread tensioner 17 and the gripper tube 15 captures the lower thread 30 there with an air flow. At the same time, a control cam provided on the nipper bobbin cover 29 slides past a lower control guide (not shown), so that the nipper bobbin cover 29 is opened. Once the nipper tube 15 has captured the lower yarn 30, the nipper tube 15 may be pivoted slightly upwards so that the nipper tube cover 29 is closed and the lower yarn 30 is mechanically fixed. The nipper tube 15 is pivoted upwards along the dotted line 32 until in front of the yarn joining device.

Once the nipper tube 15 together with the received lower yarn 30 is in place in front of the yarn splicing device, the suction nozzle 14 together with the received upper yarn can be pivoted to a position in the area of the yarn splicing device in front of the nipper tube 15.

Subsequently, the suction nozzle 14 and the nipper tube 15 continue to pivot to their respective

final positions

33, 34 and the upper and lower yarns are inserted into the yarn splicing device. At this time, the upper yarn is also inserted into the clearer, the cutting mechanism, and the opened clamping and cutting device provided below the yarn joining device. The lower thread 30 is also inserted into the piecing device, an open clamping and cutting device arranged above the piecing device.

The upper and lower yarns are now inserted into the splicing device and a true yarn splicing can be performed. Once the yarn engagement is made, the nipper tube 15 is pivoted back again to the lower position, in which the nipper tube mouth is located before the yarn run.

The suction nozzle 14 is pivoted back into its initial position and at the same time releases the loop of yarn step by step with the activation of the bobbin drive mechanism, so that the loop of yarn is still wound at a relatively low speed. The suction slots 27 are then again positioned in the cross-wound bobbin sub-regions. Similarly, the nipper tubes 15 are controlled to pivot back again.

The method 100 shown by means of the flow chart in fig. 2 involves capturing the end of the yarn that has already been wound onto the winding bobbin 3 with the suction nozzle 14. In a first step 110 a yarn defect is detected, followed by the start of a so-called controlled clearing cut. The yarn defect type is also detected and signaled.

Subsequently, in a second step 120, a yarn search program associated with the signaled yarn defect type is called from the memory unit 8. Finally in a third step 130, the yarn-seeking parameter stored in the called yarn-end seeking program is used for the catching of the falling yarn end by means of the suction nozzle 14.

Claims

1. A device (18) for clearing yarn defects from a yarn (4) classified according to different yarn defect types, the device (18) having a measuring head for measuring at least one predeterminable yarn parameter and being adapted to signal the presence of a yarn defect and a yarn defect type in the event of a difference from a value range associated with the yarn parameter and to trigger a clearing cut based on the yarn defect signal, by means of which the yarn defect runs onto a winding bobbin (3) of a textile machine which produces winding bobbins, characterized in that the device (18) is assigned a memory unit (8) in which a yarn search program for a suction nozzle (14) of the textile machine which is designed for yarn head search for winding is stored in an invokable manner for the different yarn defect types, and in that the device (18) is adapted to initiate a corresponding yarn search program depending on the signaled yarn defect type in order to use the yarn search program by means of the device The suction nozzle (14) captures the end of the upper thread which has already run onto the winding bobbin (3).

2. Device (18) according to claim 1, characterised in that for each yarn defect type a yarn search capture rate can be determined and stored, and that the yarn search program can be automatically adjusted if the capture rate differs from a limit value.

3. Device (18) according to claim 2, characterized in that the automatic adjustment of the yarn-seeking program is carried out individually for the respective station (1), for a group of products or for the entire textile machine.

4. Device (18) according to claim 1, characterized in that the storage unit (8) is constituted by a station control device, a central control unit or an external storage unit.

5. Textile machine for producing wound bobbins, comprising a device (18) according to one of claims 1 to 4 for clearing yarn defects from a yarn (4) classified according to different yarn defect types.

6. Method (100) for capturing the end of a thread on a workstation (1) of a textile machine, which produces winding bobbins, by means of a suction nozzle (14) of the textile machine, which is assigned to the winding bobbin (3), the end of the thread having already been moved onto the winding bobbin (3), comprising a first step (110) of controlled clearing cut after signaling a thread defect and a corresponding thread defect type, characterized in that in a second step (120) a thread search program associated with the signaled thread defect type is called from a memory unit (8), and in a third step (130) the end of the thread on a doff is captured by means of the suction nozzle (14) according to the called search program.

7. Method (100) according to claim 6, characterised in that the capturing rate of the yarn end of the upper yarn is determined and stored for each yarn defect type and the yarn seeking procedure is automatically adjusted if the capturing rate differs from a limit value.

8. Method (100) according to claim 7, characterized in that the automatic adjustment of the yarn-seeking program is carried out individually for the respective work station (1), for a group of products or for the entire textile machine.

9. The method (100) according to claim 7, wherein said storing is performed in a workstation control device, a central control unit or an external storage unit.

10. A storage unit (8) for retrievable storage of at least one seeking program associated with a type of yarn defect for catching a thread end of a thread that has already been run onto a winding bobbin (3) of a textile machine that produces said winding bobbin by means of a suction nozzle (14) of said textile machine, characterized in that the storage unit (8) has a seeking program for carrying out a method (100) according to any one of claims 6 to 9.