WO2016091286A1

WO2016091286A1 - Method and device for monitoring a knitting machine

Info

Publication number: WO2016091286A1
Application number: PCT/EP2014/077014
Authority: WO
Inventors: Filippo Oneda
Original assignee: Memminger-Iro Gmbh
Priority date: 2014-12-09
Filing date: 2014-12-09
Publication date: 2016-06-16
Also published as: TWI599694B; EP3230510A1; TW201625830A; CN107002326A; CN107002326B; EP3230510B1

Abstract

A method for monitoring a knitting machine comprises: delivering a yarn (6) to the knitting machine (5) by a yarn delivering device (1,21 ); measuring the yarn tension of the delivered yarn (6) by a yarn tension sensor (4,23); monitoring a yarn parameter by a monitoring means (10), wherein the monitored yarn parameter is the measured yarn tension or is derived from the measured yarn tension; and determining a stop signal for the knitting machine (5) by the monitoring means (10) when a stop condition is notified. The method especially comprises: regulating the yarn tension of the delivered yarn (6) by a tension controlling unit (9); wherein the yarn tension is adjusted by an actuator means (2) which comprises a yarn contact means (3,22); wherein the yarn tension is regulated to a reference value (Tref) of the yarn tension by adjusting the actuator means (2) depending on the measured yarn tension; and wherein the monitoring means (10) is associated to the controlling unit (9).

Description

Method and device for monitoring a knitting machine

The invention concerns a method and a device for monitoring a knitting machine according to the preamble of the independent claims.

The DE 42 13 842 describes a method and a device of a textile machine to monitor the function of the needles where the textile machine treats yarn by needles. The textile machine is e.g. a knitting machine.

In operation, the function of the needles is surveyed by measuring a condition on a yarn parameter and by evaluating the measurements to determine non-working needles. The evaluation is effected in correlation to the needle position. The measurement and the evaluation are continued until each needle is passed several times. The evaluation comprises adding together each of the measuring values corresponding to the needles.

The measurement is a measurement of the yarn tension by a yarn tension sensor. The yarn tension sensor is located between the needles and a yarn feeder which comprises a driven yarn delivering drum and which delivers the yarn with in general uniform yarn tension.

A yarn feeder disclosed in the WO 2008/043371 A1 delivers the yarn with a predetermined yarn velocity. Further known yarn feeders are e.g. storage yarn feeders, described in the WO 2007/048528A1 or yarn feeder which are mentioned as tension-controlled yarn feeder which are described e.g. in the DE 1981 1240A and DE 1981 1241 A.

A purpose of the invention is to improve a method and a device for monitoring a knitting machine e.g. in order to recognize broken needles, where little additional effort is necessary.

The problem is solved according to the independent claims.

According to a method for monitoring a knitting machine of the invention, the yarn is delivered to the knitting machine by a yarn feeding device. The yarn tension of the delivered yarn is measured by a yarn tension sensor. A yarn parameter which is the measured yarn tension or is derived from the measured yarn tension is monitored by a monitoring means. The monitoring means determine a stop signal for the knitting machine when a stop condition is notified. The stop condition is notified on the monitored yarn parameters, of course.

In particular, the yarn tension of the delivered yarn is regulated by a tension controlling unit. For this purpose, the yarn tension is adjusted by an actuator means which comprises a yarn contact means. The yarn tension is regulated to a reference value of the yarn tension by adjusting the actuator means depending on the measured yarn tension.

The monitoring means is associated to a controlling unit.

In one alternative, the monitoring means is integrated into the controlling unit. The yarn parameter is monitored by the controlling unit which comprises the monitoring means. In another alternative, the monitoring means is connected to the controlling unit or to the connection between the yarn tension sensor and the controlling unit

As the monitoring of the yarn parameter is integrated into the regulating of the yarn tension, only less additional effort is necessary. The measuring of the yarn tension of the regulatory process is advantageously used for monitoring the yarn parameter. A further yarn tension sensor between the needles and the yarn feeder is not needed.

The yarn parameter is the yarn tension or a parameter which is derived from on it, e.g. a changing of the yarn tension per time or an adjusting variable adjusting the actuator means.

In one embodiment of the invention, the method is used for monitoring a failure event. A failure event is e.g. a non-working or not sufficient working needle of the knitting machine, mentioned as broken needle event.

The monitored yarn parameter is measured by the yarn tension sensor with a measuring resolution which resolves the failure event as a pulse of the measuring values of the monitored parameter. The monitoring means notify a stop condition when at least one failure event is notified. In one embodiment for monitoring a broken needle event, the measuring resolution of the yarn tension sensor enables to distinguish one pulse for each needle.

The advantage of the method is that already a first failure event is visible and recordable. A quick notifying of a stop condition, namely when at least one failure event is identified, is possible.

A time consuming evaluation of measuring values which are added together from several passages of the needles is not necessary.

In one embodiment, the yarn parameter is monitored with a monitor clock time which is less than a period of a failure event. For this purpose, the monitoring means provide a monitor clock signal. At each impulse of the clock signal a value of yarn parameter is monitored. In case of a broken needle event as a failure event, the yarn tension changes, e.g. decreases, due to a missing stitch. The effect on the yarn tension due to the broken needle has a certain time length. The time length is about or at least the knitting time of one needle, which is the portion of one needle with reference to all needles of the revolution time of the knitting cylinder. This knitting time of one needle is mentioned as the period of the broken needle event.

To monitor the yarn parameter with a monitor clock time less than a period of the failure event, enables to recognize a separated failure event. In case of a broken needle event wherein the monitor clock time is less then the period of the broken needle event, the monitor clock time is chosen e.g. between one fifth and a half of the period. In one embodiment, a failure event is identified when the monitored yarn parameter crosses at least one parameter threshold. A parameter threshold is e.g. calculated from the measured values of the yarn parameter.

In one embodiment, the parameter threshold is determined as a certain deviation from an average value of the yarn parameter or, as an alternative, from a reference value of the yarn parameter.

In one embodiment, a stop condition is notified when the failure event recurs at least two times.

In one embodiment, a stop condition is notified when additionally the time between the failure events corresponds to the revolution time of the knitting cylinder. The revolution time depends on the velocity of the knitting machine.

In another embodiment, a stop condition is notified when additionally, at least, the time between second and a third failure events corresponds to that between a first and a second failure event.

In one embodiment, the method according to the invention comprises activating the monitoring of a yarn parameter by the monitoring means when a start event is notified and/or deactivating the monitoring when a termination event is notified.

In one embodiment, the start event and the termination event are a manual demands, e.g. inserted by to an input button of the controlling unit.

This method enables to choose an operation mode of the knitting machine which is suitable for monitoring the yarn parameter. Such an operation modus is, e.g. when all needles knit.

In one embodiment, the monitoring of the yarn parameter is automatically activated or deactivated by the monitoring means when a certain value of a predefined knitting parameter or of a predefined yarn parameter is realised.

This method enables to choose a suitable area of the knitting fabric for monitoring the knitting machine e.g. to detect non-working needles. Thus, the method is also applicable for a knitting machine with a irregular needle selection, e.g. for a socks machine.

A predefined knitting parameter is e.g. the number of the knitting needles. Other predefined knitting parameter are e.g. the number of the revolutions of the knitting cylinder or the velocity of the knitting cylinder.

In one embodiment, the predefined knitting parameter is sent from an additional or existing sensor, such as a revolution sensor, for this knitting parameter.

A predefined yarn parameter is e.g. the yarn tension. In one alternative, the monitoring means automatically activates or deactivates the monitoring of the yarn parameter when a certain value of a predefined knitting parameter is sent from a machine control unit of the knitting machine to the controlling unit.

In another alternative, the monitoring means automatically activates or deactivates the monitoring of the yarn parameter when a certain value of a predefined yarn parameter is recognised by the monitoring means.

In one embodiment, the method comprises delivering the yarn to the knitting machine by a tension-controlled yarn feeder. The actuator means of the tension-controlled yarn feeder comprises a yarn delivering wheel as contact means and a motor for driving the yarn delivering wheel. The method further comprises measuring the yarn tension of the delivered yarn by a yarn tension sensor of the yarn feeder and regulating the yarn tension by a tension controlling unit of the yarn feeder wherein the yarn tension is regulated by adjusting the motor depending on the measured yarn tension. In particular, the yarn tension is regulated by adjusting, e.g. motor revolutions of the motor and with that the revolutions of the yarn delivering wheel.

In one embodiment, the monitored yarn parameter is the measured yarn tension itself.

A device for monitoring a knitting machine according to the invention is suitable to operate the method with the feature and advantages described above. The device comprises a yarn feeding device for delivering a yarn to the knitting machine, a yarn tension sensor for measuring the yarn tension of the delivered yarn, and monitoring means for monitoring a yarn parameter. The monitored yarn parameter is the measured yarn tension or is derived from the measured yarn tension. The monitoring means is configured to determine a stop signal for the knitting machine when a stop condition is notified.

The device comprises a tension controlling unit which is configured to regulate the yarn tension of the delivered yarn, and an actuator means which comprises a yarn contact means for adjusting the yarn tension. The tension controlling unit is configured to regulate the yarn tension to a reference value of the yarn tension by the actuator means depending on the measured yarn tension. The monitoring means is associated to the controlling unit.

In one embodiment the yarn tension sensor is configured to measure the yarn tension with a measuring resolution which resolves a failure event as a pulse of the measuring values of the monitored parameter. The monitoring means are configured to notify a stop condition when at least one failure event is identified.

In one embodiment, the monitoring means is configured to identify a failure event, at least, when the monitored yarn parameter crosses one parameter threshold.

In one embodiment, the monitoring means is configured to notify a stop condition when the failure event is identified at least two times. In one embodiment, the monitoring means is configured to activate the monitoring of the yarn parameter when a start event is notified and to deactivate it when a termination event is notified.

In one embodiment, the yarn feeding device is configured as a tension-controlled yarn feeder. The actuator means comprises a yarn delivering wheel as contact means and a motor for driving the yarn delivering wheel. The tension-controlled yarn feeder comprises a tension controlling unit, which is configured to regulate the yarn tension by adjusting the motor depending on the measured yarn tension.

For monitoring the yarn parameter the tension-controlled yarn feeder is used by providing it with the monitoring means. No further apparatus is necessary. The function of monitoring the yarn parameter is integrated in to the yarn feeder and with that independent from the textile machine.

The invention is further explained using embodiments which are schematically shown in the figures. It shows:

Figure 1 a block diagram of a yarn feeding device of a first embodiment;

Figure 2 a view of tension-controlled yarn feeder delivering a yarn to needles of a knitting machine of a second embodiment;

Figure 3 a diagram showing a measured yarn tension of the second embodiment

indicating broken needles; and

Figure 4 a flow diagram of the second embodiment. First embodiment:

Figure 1 shows in a block diagram a device of the first embodiment in particular its yarn feeding device 1 . The yarn feeding device 1 comprises an actuator means 2 which comprises a contact means 3 for adjusting the yarn tension and with a yarn tension sensor 4 for measuring the yarn tension. The device is configured for monitoring a knitting machine 5 while the yarn feeding device 1 delivers a yarn 6 to it.

In particular, the device is designed for monitoring a knitting quality in operation of the knitting machine 5, while monitoring the yarn 6 which is delivered to a knitting cylinder 7 with needles 8, 8b of the knitting machine 5.

The yarn feeding device 1 comprises, e.g. a yarn storage unit, such as a drum, and a yarn brake with the contact means 3.

The contact means 3 is e.g. a brake conus or comprises one or more other brake elements.

The actuator means 2 is a mechanic, electric, electronic and/or magnetic actuator means, e.g. an adjustable spring, a motor or a magnetic actuator Not shown in figure 1 , the knitting machine 5, comprises several or a plurality of yarn feeding devices 1 which are arranged at a machine circle on the top of the knitting cylinder 7.

Shown in figure 1 , the yarn feeding device 1 further comprises a tension controlling unit 9. The tension controlling unit 9 is configured to regulate the yarn tension of the delivered yarn. In particular, the tension controlling unit 9 is configured to regulate the yarn tension to a reference value T_ref of the yarn tension by adjusting the actuator means 2 depending on the yarn tension measured by the yarn tension sensor 4.

The controlling unit 9 of the yarn feeding device 1 also comprises a monitoring means 10 for monitoring the measured yarn tension in order to monitor the knitting quality, especially for detecting a broken needle 8b. I.e. the monitored yarn parameter is the measured yarn tension itself.

In this embodiment, the monitored failure event is a broken needle event.

The monitoring means 10 is configured to determine a stop signal for the knitting machine 5 when during monitoring the measured yarn tension a stop condition is notified.

The yarn sensor 4 is provided with a measuring resolution which resolves a broken needle event as a pulse of the measuring values of the yarn tension. Especially, the measuring resolution of the yarn sensor 4 enables to distinguish one pulse for each needle 8, possibly besides in the region of a broken needle 8b.

The monitoring means 10 is configured to identify such a pulse as a broken needle event and to notify a stop condition.

In particular, the monitoring means 10 is configured to identify a broken needle event when the monitored yarn tension crosses at least one parameter threshold, e.g. a minimum tension, and to notify a stop condition when the broken needle event is identified at least two times.

The monitoring means 10 is also configured to activate the monitoring of the yarn tension when a start event is notified.

The yarn feeder 1 is connected to a machine control unit 1 1 of the knitting machine 5, by a communication connection 12, e.g. by a CAN Bus. The communications connection 12 is used e.g. to send the stop signal from the monitoring means 10 to the machine control unit 1 1 .

In operation, the yarn 6 is delivered to the knitting machine 5 by the yarn feeding device 1 . The yarn tension of the delivered yarn 6 is measured by the yarn tension sensor 4 and regulated by the tension controlling unit 9 wherein the yarn tension is adjusted by the actuator means 2.

In particular, the yarn tension is regulated to a reference value T_ref of the yarn tension by adjusting the actuator means 2, depending on the yarn tension measured by the yarn tension sensor 4. The actuator means 2 are adjusted e.g. by actuating a brake element of a yarn brake

The yarn tension is measured with a measuring resolution which resolves a broken needle event as a pulse of the measuring values of the yarn tension. The yarn tension is monitored with a monitor clock which is less than a period of a broken needle event.

The monitoring means 10 identifies the pulse as broken needle event when the yarn tension crosses at least one tension threshold, e.g. a minimum threshold. The monitoring means 10 notify a stop condition when it identifies the broken needle event at least two times and determines a stop signal for the knitting machine 5. The stop signal is sent to the knitting machine by the communication connection 12.

The monitoring of the knitting machine 5 for surveying the needles 8 of the knitting cylinder 5 is activated when the monitoring means 10 notify a start event. It is deactivated when the monitoring means 10 notify a termination event.

A monitoring condition is e.g. when all needles 8 knit.

A corresponding start event is, e.g. when a certain value of a predefined knitting parameter is notified and a corresponding termination event when another certain value of this knitting parameter is notified.

A predefined knitting parameter is e.g. the number of needles which knit. When a certain value of this number, namely the number of all needles, is sent from the knitting machine 5 to the controlling unit 9 and with that to the monitoring means 10, the monitoring means 10 automatically activates the monitoring of the yarn tension. When a different value of the number of needles is sent from the knitting machine 5, the monitoring means automatically deactivates the monitoring of the yarn tension.

In an alternative, a corresponding start event is, when a certain of a predetermined yarn parameter, e.g. of the reference value T_ref of the yarn tension is recognised by the monitoring means 10. The reference value T_ref of the yarn tension has this certain value when all needles 8 knit. The monitoring means 10 automatically activates the monitoring of the yarn tension when it recognises this certain value of the reference value T_ref of the yarn tension and it automatically deactivates the monitoring when it recognises another certain value of the reference value T_ref of the yarn tension.

In an alternative the start event is a manual input, e.g. indicating that all needles knit.

In another alternative the start event the monitoring means are also configured to execute a pattern recognition and the determine a start event at equal applicable pattern positions.

As an alternative the communication connection 12 comprises parallel lines.

In one alternative the knitting machine is a seamless machine. Second embodiment:

A second embodiment of the invention, shown in figures 2 to 4, corresponds to the first embodiment besides the following features:

A device of the second embodiment has a yarn feeding device 1 which is configured as a tension-controlled yarn feeder 21 .

The tension-controlled yarn feeder 21 comprises a yarn delivering wheel 22 which is driven by a motor and a yarn tension sensor 23. In particular, the actuator means 2 of the yarn feeder 21 comprises the yarn delivering wheel 22, which is a contact means 3, and it's motor.

The tension-controlled yarn feeder 21 comprises a tension controlling unit 9 which is configured to regulate the yarn tension by adjusting the motor depending on the yarn tension measured by the yarn tension sensor 23.

The motor and the tension controlling unit 9 are not visible in figure 2. As in the first embodiment, the tension controlling unit 9 comprises monitoring means 10. The knitting machine 5 is e.g. a socks machine.

In operation, the yarn 6 is delivered to the knitting machine 5 by the yarn delivering wheel 22 of the tension-controlled yarn feeder 21 . The yarn delivering wheel 22 is driven by the motor. The yarn tension is regulated by the controlling unit 9 which adjusts the motor, e.g. its motor revolutions, depending on the yarn tension measured by the yarn sensor 23.

The knitting quality is monitored by monitoring the yarn tension of a yarn 6 by the monitoring means 10.

Figure 3 shows, as function of the time and beginning from above, a picture of the needles 8 passing one position to which the yarn feeder 21 delivers the yarn 6, where one broken needle 8b periodically is missing, the values T of the measured yarn tension and possible threshold values T_min and T_max, the number N_w of revolutions of the yarn delivering wheel 22 and the number N_c of revolutions of the knitting cylinder 7.

During the time shown on the horizontal axis in figure 3, the one broken needle 8b appears three times, i.e. at each revolution of the knitting cylinder 7.

The values T of the measured yarn tension resolves each needle 8 of the knitting cylinder 7 as a pulse.

The effect of the broken needle is visible as higher pulses of the values T of the measured yarn tension at times ti , t₂ and t₃ , which are mentioned as broken needle pulses. The broken needle pulses extend beyond the others and cross the thresholds T_min and T_max. The time tv between two broken needle events, i.e. between broken needle pulses, is nearly the same during a constant knitting velocity. The time t_v corresponds to the time necessary for one revolution of the knitting cylinder 7. The monitoring means 10 determines a stop signal for the knitting machine 5 when a stop condition e.g. due to a broken needle is notified during monitoring the yarn tension.

The method to monitor the knitting quality is further explained my means of the flow diagram shown in figure 4.

After starting the procedure it is proved if a start event is existent. If NOT, the number of measured broken needles Nb, the clock number Kt and the time t is set to zero.

If YES, the value T of the yarn tension is measured.

The value T is proved if it is below a threshold value T_min. If NOT, the clock number Kt is set to zero. The procedure repeats with the measurement of the value T.

If YES, the clock number Kt is set to Kt + 1 .

The clock number Kt is proved if it is grater than a minimum value DIM, i.e. a minimum width of the pulse due to the broken needle 8b. If NOT, the procedure repeats with the measurement of the value T.

If YES, it is proved if the Number Nb is zero. If YES, a timer starts a measurement of time t. The procedure repeats with the measurement of the value T.

If NOT, the number Nb is set to Nb + 1 and the timer stops the time measurement, where the time tv between two broken needles events is gained.

The number Nb is proved if it is greater than 2. If NOT, a brake period Pb is set to the time tv. The procedure repeats with the measurement of the value T.

If YES, it is proved if the time tv corresponds to the period Pb, i.e. to the former time tv. If NOT, a new start event is awaited.

If YES, a stop signal is generated.

In this example of a socks machine as knitting machine 5, the knitting cylinder 7 comprises e.g. 400 needles. When knitting with a knitting velocity of e.g. 300 rpm (revolutions of knitting cylinder 7 per minute), the knitting time of one needle, i.e. the period of a pulse for one needle and, by definition, the period of a broken needle event, amounts 0,5 ms (milliseconds). A decreasing knitting velocity causes a longer knitting time per needle. The monitor clock time, i.e. the time between two impulses Kt, is chosen between on fifth and a half of the a.m. period of a broken needle event.

In case of a period of 0,5 ms, a monitor clock time of e.g. 200 ms is chosen. In order to identify broken needle events, the minimum value DIM of the number Kt of clock impulses is chosen to 2; i.e. the minimum time amounts 0,4 ms to identify a broken needle event of about 0,5 ms.

In an alternative, the value T is proved, if it is out of the region between threshold value Tmin and Tmax. List of reference signs

1 yarn feeding device

2 actuator means

3 contact means

4 yarn tension sensor

5 knitting machine

6 yarn

7 needle cylinder

8 needle

8b broken needle

9 controlling unit

10 monitoring means

1 1 machine control unit

12 communication connection

21 tension-controlled yarn feeder

22 yarn delivering wheel

23 yarn tension sensor

Claims

Method for monitoring a knitting machine (5), wherein the method comprises:

delivering a yarn (6) to the knitting machine (5) by a yarn feeding device (1 , 21 ); measuring the yarn tension of the delivered yarn (6) by a yarn tension sensor (4, 23); monitoring a yarn parameter by a monitoring means (10), wherein the monitored yarn parameter is the measured yarn tension or is derived from the measured yarn tension; and determining a stop signal for the knitting machine (5) by the monitoring means (10) when a stop condition is notified;

characterized in

regulating the yarn tension of the delivered yarn (6) by a tension controlling unit (9); wherein the yarn tension is adjusted by an actuator means (2) which comprises a yarn contact means (3, 22);

wherein the yarn tension is regulated to a reference value (Tref) of the yarn tension by adjusting the actuator means (2) depending on the measured yarn tension; and wherein the monitoring means (10) is associated to the controlling unit (9).

Method for monitoring a knitting machine (5) according to claim 1 , characterized in, for monitoring a failure event, measuring the yarn parameter by the yarn tension sensor (4, 23) with a measuring resolution which resolves the failure event as a pulse of the measuring values of the monitored yarn parameter; and notifying a stop condition when at least one failure event is identified by the monitoring means (10).

Method for monitoring a knitting machine (5) according to claim 2 characterized in identifying a failure event when the monitored yarn parameter crosses at least one parameter threshold.

Method for monitoring a knitting machine (5) according to claim 2 or 3 characterized in notifying a stop condition when the failure event is identified at least two times.

Method for monitoring a knitting machine (5) according to one of the claims 1 to 4, characterized in activating or deactivating the monitoring of a yarn parameter by the monitoring means (10) when a start event or a termination event is notified.

Method for monitoring a knitting machine (5) according to claim 5, characterized in automatically activating or deactivating the monitoring of the yarn parameter by the monitoring means (10) when a certain value of a predefined knitting parameter or of a predefined yarn parameter is realised.

Method for monitoring a knitting machine (5) according to claim 6, characterized in automatically activating or deactivating the monitoring of the yarn parameter by the monitoring means (10) when a certain value of a predefined knitting parameter is sent from a machine control unit (1 1 ) of the knitting machine (5) to the controlling unit (9). Method for monitoring a knitting machine (5) according to claim 6, characterized in automatically activating or deactivating the monitoring of a yarn parameter by the monitoring means (10) when a certain value of a predefined yarn parameter is recognised by the monitoring means (10).

Method for monitoring a knitting machine (5) according to one of the claims 1 to 8, characterized in delivering the yarn (6) to the knitting machine (5) by a tension- controlled yarn feeder (21 ); wherein the actuator means (2) comprises a yarn delivering wheel (22) as contact means (3) and a motor for driving the yarn delivering wheel (22), measuring the yarn tension of the delivered yarn (6) by a yarn tension sensor (23) of the yarn feeder (21 ) and regulating the yarn tension by a tension controlling unit (9) of the yarn feeder (21 ) wherein the yarn tension is regulated by adjusting the motor depending on the measured yarn tension.

Device for monitoring a knitting machine (5), with

a yarn feeding device (1 , 21 ) for delivering a yarn (6) to the knitting machine (5), a yarn tension sensor (4, 23) for measuring the yarn tension of the delivered yarn (6); a monitoring means (10) for monitoring a yarn parameter; wherein the monitored yarn parameter is the measured yarn tension or is derived from the measured yarn tension; and wherein the monitoring means (10) is configured to determine a stop signal for the knitting machine (5) when a stop condition is notified;

characterized in that it further comprises

a tension controlling unit (9) which is configured to regulate the yarn tension of the delivered yarn (6);

an actuator means (2) which comprises with a yarn contact means (3, 22) for adjusting the yarn tension; wherein the tension controlling unit (9) is configured to regulate the yarn tension to a reference value (Tref) of the yarn tension by adjusting the actuator means (2) depending on the measured yarn tension; and

wherein the monitoring means (10) is associated to the controlling unit (9).

Device according to claim 10 characterized in that, for monitoring a failure event, the provided yarn sensor (4, 23) is provided with a measuring resolution which resolves the failure event as a pulse of the measured values of the monitored yarn parameters and the monitoring means is configured to notify a stop condition when at least one failure event is identified.

Device according to claim 1 1 characterized in that the monitoring means (10) is configured to identify a failure event when the monitored yarn parameter crosses at least one parameter threshold.

Device according to claim 1 1 or 12 characterized in that the monitoring means (10) is configured to notify a stop condition when the failure event is identified at least two times. Device according to one of the claims 10 to 13 characterized in that the monitoring means (10) is configured to activate or to deactivate the monitoring of the yarn parameter when a start event or a termination event is notified.

Device according to one of the claims 10 to 14 characterized in that

the yarn feeding device (1 ) is configured as a tension-controlled yarn feeder (21 ); wherein the actuator means (2) comprises a yarn delivering wheel (22) as contact means (3) and a motor for driving the yarn delivering wheel (22); and

wherein the yarn feeder (21 ) comprises a tension controlling unit (9), which is configured to regulate the yarn tension by adjusting the motor depending on the measured yarn tension.