EP1819857B1 - Thread feeding device with return operation - Google Patents

Description

The invention relates to a yarn feeding device, which is particularly adapted for use on knitting machines or other thread-consuming machines that sometimes return thread. Such machines are, for example, flat knitting machines with a reciprocating carriage, wherein at least at one of the carriage reversal points a short yarn return can occur. Thread return can also occur in flat knitting machines, if they have multiple knitting locks and threads, of which individual can be switched inactive for one or more strokes.

Excessive yarn returns can also occur on circular knitting machines, especially in the so-called fully-fashioned technique. In this technique, not only threads are designed and laid, but it may be necessary in certain knitting sections to rotate the knitting cylinder more or less one or more times backwards. This process, in which the knitting cylinder is repeatedly rotated forwards and backwards, is called "swinging". It can come to the yarn return of half a meter thread and more. The yarn feeding devices must take into account such yarn return delivery.

From the DE 40 32 402 C2 For example, a storage specialist is known for use on flat knitting machines combined with a separate dynamic thread store. The yarn coming from the storage feeder is fed to the flat knitting machine via a yarn store. The yarn store is formed by a long torque acted upon lever, at its free end a thread eyelet is formed. The lever is pivotally mounted. In addition, a yarn brake and a yarn tension sensor are arranged in the yarn path. The amount of thread returned during the carriage reversal is absorbed by first closing the controlled thread brake, so that no further thread can be withdrawn by the storage specialist. Then, the pivot lever is subjected to torque, so that this receives the returned by the yarn guide of the flat knitting machine thread by pulling an acute-angled thread loop in the length.

In the new carriage reversal of this thread supply is first used up and then the thread brake released again to deduct the thread of the Speicherfournisseur.

This type of thread storage is particularly suitable for Speicherfournisseure, in their application, the knitting machine picks up the thread from the Speicherfournisseur. However, this contradicts the positive feeders principle of the knitting machine to allocate a predetermined amount of thread.

An intermediate storage of thread is also according to the yarn delivery device DE 37 32 102 C1 possible. This document discloses an electronically controlled positive feeder with a looped by the thread Fadenlieferrad. The thread running to the knitting machine is passed through a thread store. To this belongs an almost 360 ° swivel mounted lever, through whose end the thread runs. Within the circle described by the thread loop several thread support elements are arranged, which define a polygonal thread store. If thread is left between the thread delivery wheel and the connected machine and is not picked up by the machine, this amount of thread is deposited by the lever on the thread support elements.

This type of yarn delivery is particularly suitable for yarn delivery with a constant yarn tension.

From the WO 2003/093550 A1 For example, an apparatus for controlling the supply of yarn to a textile machine is known. It has means for measuring and changing the speed of the yarn with a rotating component. The device is provided with receiving means for the yarn, which are arranged in front of the means for measuring and changing the speed.

A thread store for recording all thread lengths is from the DE 36 29 699 A1 known, which relates to a method for digital thread length control on textile machines. The thread store is arranged after a feeder motor and in front of a control motor.

The DE 34 29 207 C2 describes a yarn feeding device with a rotatable delivery element which is driven by a controllable drive motor. The speed of the drive motor is synchronized with the withdrawn amount of thread.

Furthermore, from the DE 34 29 193 C1 a device for winding or winding threads from or on a yarn package known, in which the thread is guided by means of a winding finger on the yarn package. The winding finger sits on a shaft arranged concentrically to the yarn package, which is driven by an electric motor. The winding finger runs around the outer circumference of the yarn package. If necessary, the electric motor can be controlled in such a way that the yarn is unwound from the yarn package or even onto it is rewound. To control a thread tensioner is provided, with which the thread tension is checked. If there is a need for a return delivery, the winding finger rewinds the thread until the thread tensioning roller is returned to its normal position by the tensioning thread.

Bobbins are generally grouped together on so-called bobbin creels, of which the threads are only passively removed, if required, even over longer distances. Inclusion of the yarn packages in the active winding and unwinding is hardly desired in many cases and with larger distances between the yarn package and the knitting machine also not possible.

On this basis, it is an object of the invention to provide a yarn feeding device that can handle occasionally occurring yarn returns in modern knitting machines or other textile machines.

• Das Fadenliefergerät nach Anspruch 1 weist ein Fadenlieferrad auf, das mittels einer Antriebseinrichtung in zwei entgegengesetzten Drehrichtungen antreibbar ist, um den Faden zu fördern. Der Fadenablauf erfolgt im Wesentlichen tangential. Eine erste Drehrichtung dient als Vorwärtsdrehung in Normalbetrieb der Lieferung von Faden in Fadenlieferrichtung zu einer Fadenverbrauchsstelle. Die Rückwärtsdrehung dient in Rückholbetrieb zur Rücknahme des Fadens, der in Rückgaberichtung von der Fadenverbrauchsstelle zurückkommt. Dieser wird dann auf das Fadenlieferrad rückgewickelt. An der Einlaufseite des Fadenlieferrads frei werdender Faden wird in einem Fadenspeicher zwischengepuffert. Dieser ist bezüglich der normalen Fadenlieferrichtung vor dem Fadenlieferrad und zwischen einer Fadenbremse und dem Fadenlieferrad vorhanden. Die Anordnung des Fadenspeichers vor dem Fadenlieferrad und dabei in unmittelbarer Nachbarschaft desselben lässt einerseits die direkte Lieferbeziehung zwischen dem Fadenlieferrad und der Strickmaschine bestehen, so dass das Fadenlieferrad der Strickmaschine die gewünschte Fadenmenge zuteilen oder abnehmen kann, und andererseits wird der Faden ohne nennenswerten Einfluss auf die Spannung in dem Fadenwickel und in dem Abschnitt zwischen Fadenlieferrad und Fadenverbrauchsstelle abgespeichert.

This object is achieved with the yarn feeding apparatus according to claim 1 or a method according to claim 28:

• The yarn feeding device according to claim 1 has a yarn feed wheel which can be driven by means of a drive device in two opposite directions of rotation in order to convey the yarn. The thread run is essentially tangential. A first direction of rotation serves as forward rotation in normal operation of the delivery of thread in the yarn feeding direction to a yarn consumption point. The reverse rotation is used in return operation to return the thread, which comes back in the return direction of the thread consumption point. This is then rewound onto the yarn feed wheel. At the inlet side of the yarn feed wheel freed thread is buffered in a thread store. This is available with respect to the normal yarn feeding direction before the yarn feed wheel and between a yarn brake and the yarn feed wheel. The arrangement of the yarn store before the yarn feed wheel and thereby in the immediate vicinity of the same can on the one hand the direct supply relationship between the yarn feed and the knitting machine exist, so that the yarn delivery of the knitting machine can allocate or decrease the desired amount of thread, and on the other hand, the thread without appreciable influence on the Tension stored in the thread winding and in the section between Fadenlieferrad and thread consumption point.

The yarn storage preferably has a concentric to the yarn feed wheel arranged yarn storage surface, either as a contiguous, uninterrupted surface or as a discontinuous surface, for. B. in the form of several individual surfaces may be formed. The individual surfaces can be, for example, support areas of pens or the like. The arrangement concentric with the yarn feeding wheel allows the uniform winding and unwinding of the yarn fed back from the yarn feeding wheel on its inlet side with a uniform tension. Preferably, the thread store is associated with a thread layer, which hangs up the yarn coming from the yarn feed on the storage surface and decreases from this again. The suture layer may be formed by a thread guide eye which, for example, is guided by a suitable lever on a circular path concentric with the yarn feed wheel. This arrangement allows a uniform winding and unwinding of the thread without significant voltage fluctuations. Especially with elastic threads is thus avoided that the thread is cached with different strains. It also prevents the thread from coming out of the thread store is again performed on the yarn feed wheel, there with different, ie fluctuating voltages, running in the winding on the yarn feed wheel. Overall, the concentric arrangement, as described above, thus benefits the knit quality.

The thread-laying device is preferably assigned a thread-laying drive device, which is independent of the drive device of the yarn feed wheel. For example, both drive devices are formed by electric motors. Both electric motors can be controlled by a control device which moves the thread leveler and the yarn feed wheel coordinated with each other. In this case, the control device preferably differentiates between several operating states, e.g. according to claim 9. Thereafter, the controller allows the thread-laying and the yarn feeding device in return operation with matched speeds rotate backwards, so that the retrieved thread is deposited on the thread store, without new thread is tightened in the thread store. When returning to normal operation, the yarn reserve thus formed is first used up, with the yarn feed wheel and the yarn feeder rotating with matched rotational speed forward. If the thread reserve is used up, the thread feeder remains z. B. are in a fixed position, wherein the yarn feed wheel continues to rotate unabated forward. From the time the yarn laying is stopped, the yarn feeding wheel then picks up the yarn from the yarn package.

The advantage of this device is that a connected knitting machine can commute as often as desired without consuming thread. The thread is unwound at each shuttle on the thread storage on and from this again. The speed of the thread leveler and the Fadenlieferrads are coordinated so that no thread is made up by the yarn package, so that the total amount of yarn present in the yarn feeding device does not increase. With the oscillation of the knitting machine, the amount of yarn of the yarn feeding device oscillates between a maximum value and a minimum value, whereby these can differ by more than one meter.

The drive device of the yarn delivery wheel and the thread-laying drive device are each formed by an electric motor, preferably a position-controlled electric motor. As an alternative, however, it is also possible to provide a gear and a coupling device between the yarn feed wheel and the yarn feeder in order to connect the yarn feeder to the yarn feed wheel during the filling and emptying of the yarn store, respectively. The thread-laying drive device is formed in this case by a transmission clutch brake combination. However, it is preferred because of the better controllability of the own electromotive drive of the thread leveler.

Preferably, the yarn feed wheel is driven in normal operation at a predetermined speed. The predetermined speed can be derived from the operating speed or speed of the knitting machine. It is desirable to synchronously operate the yarn feed wheel and the knitting machine in a predetermined speed ratio. This operation is called positive operation. The yarn delivery wheel divides the knitting machine to the desired amount of thread and thus determines the mesh size of the knitted fabric. To compensate for dynamic processes when starting and stopping the Fadenlieferrads a yarn store with low storage capacity between the yarn feed wheel and the knitting machine can be provided. This thread store However, it does not serve the caching of retrieved thread. In any case, its capacity is insufficient. It is only intended for buffering voltage spikes, which otherwise might occur during switch-on processes (starting and stopping of the yarn feed wheel). In the simplest case, this yarn storage is formed by a thin, light and resilient lever that holds a thread loop.

When retrieving thread can also be worked with a given Fadenlieferraddrehzahl. However, it is preferred to effect the yarn retrieval by voltage control, i. under control of the thread tension. Thus, the yarn feeder is constantly switched between positive operation and voltage-controlled operation when commuting the knitting machine (positive delivery for normal operation and voltage control for return operation).

Both the thread layer and the yarn feed wheel are preferably connected to angle encoders. The control device is preferably provided with a counter or other monitoring device, which counts the angle steps passed through by the thread layer and preferably also the angular steps passing through the thread delivery wheel, in particular during return operation. Alternatively, the angle traveled by the thread layer as well as the thread delivery wheel can also be registered in another way. The controller monitors in this way the amount of buffered in the thread storage thread. You can switch in normal operation with quiescent thread layer, if the entire forward registered path is traversed backwards or alternatively if the thread layer has reached a predetermined fixed position. Approaching this fixed position, the suture layer can move from its normal speed are braked gradually to its zero speed to avoid jerky thread tension changes on the inlet side of the yarn feed wheel. The thread running on the thread delivery wheel is relieved in this way. In cooperation with the pattern memory of the knitting machine, it can be ensured that this gradual deceleration only takes place when the pendulum operation is terminated in order to avoid an otherwise occurring gradual filling of the thread store.

The control of the yarn feeding device is preferably carried out by the machine control, in particular their pattern memory. This provides the data on the quantities of yarn to be delivered, which correspond to yarn feed wheel speeds, as well as the times for delivery start and end of delivery. The yarn feeder converts these values as error-free as possible. It is also possible to operate the yarn feeding device self-learning. For this purpose, e.g. the thread tension during trial operation voltage controlled to a setpoint. In this case, the yarn feed wheel speeds of all yarn feed wheels of all active yarn feed devices are monitored and a suitable mean value is determined as the desired value for the later positive operation.

In addition, it is possible to monitor the self-adjusting thread tensions by means of a yarn tension sensor during positive operation and, if this deviates from a desired value, to readjust elements of the knitting machine. The adjustment can also be limited to cases where the deviation exceeds a threshold. Nachzustellende elements of the knitting machine can be knitting locks or the goods deduction. It is also possible to refrain from an adjustment of the knitting machine or its elements and in exceeding or falling below given thread tension limits only to generate an alarm signal or a shutdown signal.

The suture layer can further be used to substantially improve the dynamics of the suture delivery wheel. It turns out, namely, that with a sudden yarn requirement from zero to high delivery speed not only the drive device and the yarn delivery wheel itself must be accelerated, but also the entire yarn from the yarn package to the yarn consumption point. Here, the thread is to accelerate and also stiction is overcome. The thread running on the input side of the yarn feed wheel brakes the yarn feed wheel. The acceleration of the same can be significantly improved if the suture just before such an acceleration phase produces a smaller reserve of thread on the thread store and if the suture with the start of Fadenlieferrads is also accelerated to the Fadenlieferrad first with thread from the thread store and only when approaching to supply its fixed position with thread from the yarn package. The thread store serves to decouple the yarn feed wheel during its acceleration phase in terms of power from the yarn package.

It is also possible to prematurely start or stop the yarn feed wheel in anticipation of a sudden increase in yarn requirement or drop in yarn requirement (pattern in advance). This can be up to a certain degree to compensate for the inertia of the yarn feed wheel and connected components and reduce thread tension peaks or yarn tension drops at the beginning and end of delivery.

Fig. 1

ein erfindungsgemäßes Fadenliefergerät in einer Vorderansicht,

Fig. 2

das Fadenliefergerät nach Figur 1 in einer längs geschnittenen und teilweise schematisierten Darstellung;

Fig. 3

das Fadenliefergerät nach Fig. 1 und 2 in einer schematisierten perspektivischen Darstellung,

Fig. 4

das Fadenliefergerät nach Fig. 1 bis 3 in schematisierter Darstellung in Normalbetrieb,

Fig. 5 bis 9

das Fadenliefergerät nach Fig. 4 in Rückholbetrieb in verschiedenen Positionen und

Fig. 10

das Fadenliefergerät nach Fig. 4 in einer Startvorbereitungsphase vor Normalbetrieb.

Further details of advantageous embodiments or developments are the subject of the drawing, the Description or claims. In the drawing, an embodiment of the invention is illustrated. Show it:

Fig. 1

an inventive yarn feeding device in a front view,

Fig. 2

the yarn feeding device after FIG. 1 in a longitudinal and partially schematic representation;

Fig. 3

the yarn feeding device after Fig. 1 and 2 in a schematic perspective view,

Fig. 4

the yarn feeding device after Fig. 1 to 3 in a schematic representation in normal operation,

Fig. 5 to 9

the yarn feeding device after Fig. 4 in return mode in different positions and

Fig. 10

the yarn feeding device after Fig. 4 in a start-up phase before normal operation.

In FIG. 1 is a yarn feeding device illustrated, for example, for the delivery of hard (less elastic) or elastic threads used on flat knitting machines or circular knitting machines. In particular, the yarn feeding device 1 is suitable for yarn delivery on knitting machines, which have time-varying yarn requirements and / or temporarily return yarn. The yarn feeding device 1 has an example also from FIG. 2 apparent carrier 2, on which a drive device 3 is held for a yarn feed wheel 4. It is represented as a hexagon. In practice, it can also be mehrflüglig and form, for example, a hexagon. The drive device 3 is formed, for example, by an electric motor 5, the armature 6 is connected to an output shaft 7, which carries the yarn feed wheel 4. In addition, it may, for example, be connected at its other end with an angle encoder 8, which serves to detect the current rotational position of the armature 6. The angle transmitter 8 or an associated electronic circuit 9 is connected to a control device 11 which serves to drive stator windings 12 of the electric motor 5.

The yarn feed wheel 4 is preferably designed to allow particularly large spins, particularly low in inertia. For this purpose, it has a number of mutually identical in different radial directions oriented wire brackets 13, 14, 15 (and others without separate reference numeral). The wire hanger 13, 14, 15 are taken on a hub 16 which sits on the output shaft 7. They are each approximately U-shaped, wherein they have a central, straight portion 17 for the filament winding and in particular on the drive device 3 side facing a radially outwardly directed projection 18. This marked an inlet side 19 of the yarn feed wheel 4th

On the inlet side 19 of the yarn feed wheel 4, a yarn feeder 21 is provided which belongs to a yarn store 22. To the yarn store 22 also includes a here preferably frusto-conical from the yarn feed 4 away tapered yarn storage surface 23 which is arranged concentrically to the drive shaft 7. It is preferably substantially shorter in the axial direction of the drive shaft 7 than the sections 17 of the wire bracket 13, 14, 15th

The yarn feeder 21 bridges the axial distance between the yarn storage surface 23 and the inlet side 19 of the yarn feed wheel 4. ceramic tube 24, which forms a thread eyelet. It is supported by a circulation lever 25, which is rotatably supported by means of at least one corresponding bearing 26 on the carrier 2 about an axis of rotation oriented concentrically to the drive shaft 7.

The circulation lever 25 is associated with a thread-laying drive device 27, to which a preferably position-controlled electric motor 28 belongs. Its output shaft 29 is connected via a gear connection in the form of two gears 31, 32 with the circulation lever 25. The electric motor 28 is controlled by the control device 11. It is connected thereto with signal lines 33 and with control lines 34 for driving its windings with the electric motor 28. Corresponding signal lines 35 and drive lines 36 are also present for the electric motor 5.

The thread-laying drive device can be assigned a locking device 37 for locking the circulation lever 25 in a fixed position. The locking device 37 may be actuated by an electromagnet 38, which may be actuated by the control device 11 can. If the thread layer 21 is to perform more than one revolution, the locking device 37 is transferred into the release position, ie unlocked. For this purpose, for example, a stop pin 38a is provided, which is movable by the electromagnet 38 between a blocking position and a stop position.

On the carrier 2, a thread tension sensor 39 is also mounted, which serves to detect the tension of the running thread 41. It has a thread support pin 42 over which the thread 41 runs at an obtuse angle, it is connected to a corresponding force measuring device 43, which supplies a thread tension measured value to the control device 11 or any other suitable device. The thread tension sensor 39 may as shown FIG. 1 can be housed in a part housing 44, on the front side of a display 45 and a plurality of operating elements 46, 47 can be accommodated. The specified by the sub-housing 44 and the thread support pin 42 yarn path is, in particular FIG. 2 can recognize, oriented at an obtuse angle to the axis of rotation of the yarn feed wheel 4.

As FIG. 3 can be seen, the thread-laying 21 is used in particular to wind thread 41 on the thread storage surface 23 or unwind from this. The thread 41 is guided before it reaches the thread storage surface 23 through a thread inlet eye 48. According to the invention, he will previously run through a yarn brake 49, the only in FIG. 4 is illustrated schematically. The thread brake 49 is preferably a non-controlled thread brake that adjusts a constant thread tension. If necessary, however, their braking elements can also be acted upon by a controlled clamping force. For this purpose, the brake elements, for example, with an electrical adjusting device (eg an electric motor or an electromagnet, a piezo actuator or the like) controlled by the controller 11. Preferably, this controls the yarn brake 49 so that the braking force is increased when the yarn feeder 21 fills or empties the yarn store 22 while the braking force is reduced when the yarn store 22 is empty and the yarn feed wheel delivers yarn positively to the knitting machine from the yarn package follow suit.

Before the thread brake 49, a non-illustrated Einlaufabsteller is preferably provided. This works preferably optically. But it can also be provided a simple mechanical stop in the form of a mechanical feeler lever. The thread monitoring in front of the yarn feed wheel 4 is preferred to the yarn monitoring behind the yarn feed wheel 4. The thread tension sensor 39 is less suitable for thread monitoring, because thread tension values of zero can occasionally occur even with proper operation. In addition, it should be prevented in any case that the end of a broken thread runs into the machine.

It is also possible to use the thread layer 21 as a stand-off, ie to monitor the thread. For this purpose, the force exerted by the thread on the thread layer force is monitored. If this drops to too low a value or zero while the yarn feed wheel is running, this is considered a yarn breakage. In practice, this can be achieved, for example, by holding the thread-laying element 21 away from the thread a few mm away from the stop (pin 38a), but elastically holding it too taut. If the suture strikes the pin 38a, this is detected by a suitable sensor and evaluated as a thread breakage.

• Das Fadenliefergerät unterscheidet mehrere Betriebsarten. In Figur 4 ist Normalbetrieb dargestellt. Dabei wurde zur Verdeutlichung der Verhältnisse eine weitgehende abstrahierte Darstellung gewählt. Die Fadenspeicherfläche 23 ist zur Unterscheidung von Fläche mit Faden und Fläche ohne Faden zunächst nur gestrichelt dargestellt. Von dem Fadenlieferrad 4 ist in allen Figuren 4 bis 11 lediglich ein einziger Drahtbügel 14 zur besseren Verfolgbarkeit der Drehung des Fadenlieferrads 4 mit einem Bezugszeichen versehen. Außerdem ist er durch ein schwarzes Ende gekennzeichnet. Des Weiteren ist in den Figuren 4 bis 11 von dem Fadenleger 21 lediglich das Röhrchen 24 veranschaulicht.

The yarn feeding device after Figure 1 to 3 Works according to the following functional description:

• The yarn feeder distinguishes between several operating modes. In FIG. 4 is normal operation. In this case, a largely abstract representation was chosen to illustrate the circumstances. The yarn storage surface 23 is initially shown only by dashed lines to distinguish the surface with thread and surface without thread. Of the yarn feed 4 is in all FIGS. 4 to 11 merely a single wire bracket 14 for better traceability of the rotation of the yarn feed wheel 4 provided with a reference numeral. It is also marked by a black end. Furthermore, in the FIGS. 4 to 11 only the tube 24 is illustrated by the thread layer 21.

It stands in alignment with the thread inlet eye 48. The yarn feed wheel 4 rotates in the direction of the arrow 50, for example, counterclockwise. The thread 41 runs tangentially in a direction indicated by the arrow 52 yarn feeding direction of the yarn feed wheel 4 and via the yarn tension sensor 39 to a yarn consumption point. The thread wraps around, how special FIG. 3 can be seen, the yarn feed 4 several times and is thus promoted essentially without slippage. However, it may also slippage causing means, such as. Fadenabhebestifte or the like, may be provided. Slippage can also be made possible by a slip clutch between the drive shaft 7 and the yarn feed wheel or by a reduction of the looping of the yarn feed wheel 4 through the yarn 41. For example, slip can be generated by only very few turns of thread are placed around the yarn feed wheel 4. It is also possible to thread in less than a whole Wrap around with the yarn feed wheel 4 in contact (for example, a three-quarters wrap) to bring. The control device 11 determines the speed of the yarn feed wheel 4 and thus the yarn delivery speed and yarn delivery quantity. This operating mode is called positive mode (with tangential thread run).

If the yarn requirement of the connected knitting machine stops, the yarn feed wheel 4 stops. No more yarn is delivered. Out of a stop, normal operation can be resumed at any time FIG. 4 be recorded.

However, when the knitting machine or other machine starts to release thread 41, ie feed back, the yarn feeding device 1 assumes its return operation. The yarn feeding device immediately detects a reduction in the thread tension on the thread support pin 42 and now tries to restore the thread tension by reversing the drive device 3. It now performs a reverse rotation in the clockwise direction according to arrow 53 in FIG. 5 , It takes the thread 41 thus in the return direction according to arrow 54 with the yarn feed wheel 4 again. The thread 41 runs tangentially on the yarn feed wheel 4. In FIG. 5 the yarn feed wheel 4 has already turned backwards by about 30 °. This is by comparing the positions of the wire bracket 14 in the FIGS. 4 and 5 seen. In order to maintain the thread tension in front of the yarn feed wheel 4, the control device 11 has for this purpose the thread layer 21 driven, so that the tube 24, as FIG. 5 shows, has been adjusted by about 15 ° in the clockwise direction (arrow 51). This corresponds to the existing between the inlet eye 48 and the wire hanger 14 thread length in FIG. 5 now exactly the sum of the in FIG. 4 existing thread length between the inlet eye 48 and the wire bracket 14 plus the fed-back yarn length. The adjustment of the yarn layer 21 is preferably not voltage controlled but "positive", ie according to a calculated adjustment, which is determined from the detected reverse rotation of the yarn feed wheel. For detecting the yarn tension on the yarn layer 21 no means are provided. If necessary, however, a voltage-controlled actuation of the thread layer 21 is possible.

Upon further feeding back of the thread 41, the states follow FIGS. 6 to 9 on. As FIG. 6 illustrates the tube 24 of the thread layer 21 while the thread 41 while on the thread storage surface 23 from. When retrieving the yarn feeder 21 runs much slower than the yarn feed 4. In FIG. 6 the thread-laying device 21 has performed approximately a quarter turn, while the wire bow 14 and thus the yarn feed wheel 4 have performed more than half a turn.

• wobei α der von dem Fadenleger durchlaufene Winkel,
• β der von dem Fadenrad durchlaufene Winkel,
• r₁ der Durchmesser des Fadenspeichers und
• r₂ der Durchmesser des Fadenlieferrads ist.

Continued return delivery causes the thread layer 21, such FIG. 7 shows, with further rotation of the yarn feed wheel 4 gradually runs around the yarn storage surface 23 and this first with a turn ( FIG. 8 ) and, if necessary, with further turns ( FIG. 9 ). Due to the conicity of the yarn storage surface 23, the turns of the thread in the yarn store 22 lie next to one another and preferably not one above the other. The speed ratio between the suture layer 21 and the yarn feed wheel 4 and the respective angle passed through are calculated to be: $$\frac{\alpha }{\beta }=\frac{r_1}{{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0002.png"\; state="\{\{state\}\}">r</figure-callout>}}_2}$$

• where α is the angle traveled by the thread layer,
• β is the angle traveled by the thread wheel,
• r _{1 is} the diameter of the thread store and
• r _{2 is} the diameter of the yarn feed wheel.

Thus, no thread is pulled through the thread inlet eye 48. In addition, the thread brake 49 may be braked to prevent tightening of the thread.

If the knitting machine stops delivering thread, the return operation is terminated. This can, for example, in the in FIG. 9 illustrated position of the thread layer 21 and the yarn feed wheel 4 happen. If the knitting machine now starts to remove thread, the yarn feeding device changes to a modified normal mode, in which now no longer tension-controlled thread taken back, but quantity-controlled, ie 4 thread is supplied to the knitting machine under speed specification for the yarn feed wheel. The arrows turn in the FIGS. 9 to 5 around. Now run the thread layer 21 and the yarn feed 4 counterclockwise with the above angular or speed ratio, whereby the yarn layer 21 decreases the thread from the yarn storage surface 23 and the yarn feed 4 on its inlet side 19 zuleitet. Again, no thread is pulled through the thread inlet eye 48. This modified mode of operation continues until the yarn store 22 is empty, ie until the tube 24 reaches the position indicated in FIG FIG. 4 illustrated position adjacent to the thread entry eye 48 has taken.

When this point is reached, the thread-laying 21 stops, wherein the yarn feed wheel 4 continues to rotate unchanged. Only now is normal normal operation achieved. While only the yarn wound on the yarn storage surface 23 has been taken up again in modified normal operation and fed to the yarn delivery wheel and thus the knitting machine, yarn is now drawn against the action of the yarn brake 49. The return operation and the modified normal operation can alternate as often as desired. Neither the return operation nor the modified normal operation thread is drawn from the yarn package through the thread brake 49.

While it has been assumed in the foregoing description that the suture drive mechanism 27 is precisely positionally controlled, it should be understood that this need not necessarily be so. It is also possible to use a non-position-controlled electric motor 28 while only monitoring the position of one of the two gears 31, 32. In the simplest case, it may be sufficient to provide only one or more marks on the toothed wheel 32 or the toothed wheel 31, for example in the form of optical marks (holes) or magnets, which are then detected by optical sensors or magnetic sensors (Hall sensors) , When the yarn feed wheel 4 rotates backward, the Fadenlieferradposition or rotation is detected and the motor 28 for moving the yarn layer 21 is driven. The motor 28 can be supplied with a controlled current to produce a predetermined torque. This should be less than the torque required to tighten thread through the thread brake 49. In this way, the yarn store 22 only takes up the yarn delivered by the yarn feed wheel 4. Turns the yarn feed wheel 4 its direction of rotation to the thread store 22 again empty, it works against the low tension of the thread layer 21. This can also be reduced in this case by the current of the motor 28 is reduced. Reaches the suture 21 his example, by the Hall sensor and the magnet on the gear 31 (or 32) marked position (fixed position) the sizer 21 is braked, ie locked in fixed position and the yarn feed 4 fetches overcoming the yarn brake 49 fresh thread from the Garnspule after.

Notwithstanding the above description, it should be noted that the modified normal operation with Aufzehr the memory reserve as well as the normal operation with thread recovery from the upstream coil voltage controlled under control of the thread tension sensor 39 can run.

A modified embodiment of the yarn feeding device 1 illustrates schematically FIG. 10 , The modification consists in the formation of the yarn storage surface 23, which is divided here into individual surfaces 55, 56. These are formed by individual pins 57, 58, which are arranged as a wreath in the vicinity of the yarn feed wheel 4. Otherwise, the previous description applies.

The yarn feeding device 1 allows a particularly fast starting and stopping of thread deliveries. For this purpose, it can assume a dynamic mode, which is described below with reference to FIG FIG. 11 is illustrated. The dynamic mode of operation assumes that a smaller reserve of thread is built up in the yarn store 22 before the start of delivery, for example, as FIG. 11 illustrated. The thread reserve can also be lower. It may have been constructed by the yarn layer 21 in the standing delivery wheel 4 in the illustrated position, that is, for example, has been rotated by a few degrees in the clockwise direction. In this case, thread 41 is dragged through the thread inlet eye 48 and over the thread storage surface 23. This can be done preventively whenever the yarn feed wheel 4 stops out of normal operation. It can also happen controlled by the pattern memory of the knitting machine only when a highly dynamic start, ie a sudden increase in the thread requirement is expected.

In FIG. 11 the yarn feeder is illustrated in state prepared for the highly dynamic start. Now comes the start signal for the yarn feeding device 1 of the knitting machine, the yarn layer 21 and the yarn feed wheel 4 are accelerated simultaneously against the clockwise direction (arrows 50, 51a). As a result of the acceleration of the thread delivery arm, the yarn delivery wheel 4 is temporarily freed temporarily, ie for its run-up phase, from the load of the thread otherwise being towed by it to the yarn package. For the startup phase, the yarn feed wheel 4 has thus overcome only its own and the inertia of the yarn winding carried by him. If, for example, it reaches its setpoint speed after a half or three-quarter revolution, the string delivery arm 21 arrives at its fixed position below the thread entry eye 48 and stops there gradually, ie gently, until it stops. This mode avoids yarn tension peaks between the yarn feed wheel 4 and the knitting machine in case of sudden yarn requirement.

A yarn feeder 1 has a yarn feed wheel 4 with a drive device 3 and a yarn store 22 with a yarn feeder 21, which has its own yarn feeder drive 27. A control device 11 controls both drive means 3, 27 so that on the one hand refiner positive operation of the yarn feed wheel 4 and on the other hand, a thread withdrawal is made possible during oscillation of the knitting machine. In addition, the dynamics of a yarn feeding device 1 can be improved with this configuration.

LIST OF REFERENCE NUMBERS

1

Yarn feeder

2

carrier

3

driving means

4

yarn feed wheel

5

electric motor

6

anchor

7

output shaft

8th

angle encoder

9

circuit

11

control device

12

stator

13, 14, 15

wire hanger

16

hub

17

section

18

head Start

19

inlet side

21

thread layer

22

yarn storage

23

Yarn storage area

24

tube

25

recycle lever

26

camp

27

Thread guide driving device

28

electric motor

29

output shaft

31, 32

gears

33, 35

signal lines

34, 36

control lines

37

locking device

38

electromagnet

38a

stop pin

39

Yarn tension sensor

41

thread

42

Thread support pin

43

Force measuring device

44

Enclosures

45

display

46, 47

controls

48

Fadeneinlaufose

49

thread brake

55, 56

individual areas

57, 58

pencils

52

Thread delivery direction (arrow)

54

Return direction (arrow)

51a, 50

Forward rotation (arrow)

51, 53

Reverse rotation (arrow)

Claims (28)

1. Yarn delivering device (1), particularly for knitting machines having a yarn return operating mode, comprising a yarn delivery wheel (4) which has an intake side (19) and a storage section (17) for receiving a yarn winding,
   a drive device (3) which is connected to the yarn delivery wheel (4) and can be operated in two opposite directions of rotation for delivering yarn (41) in the yarn delivery direction (52) to a yarn using station during normal operation with forward rotation (50), and for rewinding the yarn (41), returned from the yarn using station in the yarn return direction (54) back onto the yarn delivery wheel (4) in a return delivery operation with reverse rotation (53),
   a yarn storage unit (22) which is arranged upstream of the yarn delivery wheel (4) as viewed in the yarn delivery direction (52) for the temporary storage of yarn (41) returned by the yarn delivery wheel (4) at its yarn intake side (19) during reverse rotation (53),
   characterised in that the yarn storage unit (22) is arranged between a yarn brake (49) and the yarn delivery wheel (4).
2. Yarn delivering device according to claim 1, characterised in that the yarn brake (49) is a controlled yarn brake, the braking force of which can be switched by an electric control signal between at least two values.
3. Yarn delivering device according to claim 1, characterised in that the yarn storage unit (22) has a yarn storage surface (23) concentric to the yarn delivery wheel (4).
4. Yarn delivering device according to claim 3, characterised in that the yarn storage surface (23) has a cohesive structure.
5. Yarn delivering device according to claim 3, characterised in that the yarn storage surface (23) is divided into individual surfaces (55, 56).
6. Yarn delivering device according to claim 1, characterised in that a yarn laying device (21) is associated with the yarn storage unit (22).
7. Yarn delivering device according to claim 6, characterised in that the yarn laying device (21) has a yarn guiding eyelet (24) which is guided on a circular path concentric to the yarn delivery wheel (4).
8. Yarn delivering device according to claim 6, characterised in that a yarn laying device drive (27) is associated with the yarn laying device (21).
9. Yarn delivering device according to claim 8, characterised in that the drive (3) and the yarn laying device drive (27) are controlled by a control device (11) which operates according the following control scheme:

   a) during normal operation without previous yarn return operation the control device causes the yarn laying device (21) to remain in a fixed position and causes the drive (3) to rotate with a forwards rotation (50),

   b) during the yarn return operation the control device causes the drive (3) to rotate in the reverse direction (53) and causes the yarn laying device (21) to rotate in the same reverse rotational direction at a reduced speed,

   c) during normal operation with previous yarn return operation, the control device causes the drive (3) to rotate in the forward direction (50) and causes the yarn laying drive (27) to also rotate in the forward direction, but at a reduced speed, until it travels the path covered under a) and/or until it reaches its fixed position.
10. Yarn delivering device according to claim 9, characterised in that the yarn laying device (21) and the yarn delivery wheel (4) run at speeds which are in a fixed ratio to one another during rotation both in the forward and in the reverse direction.
11. Yarn delivering device according to claim 10, characterised in that the speed ratio is set in such a manner that the yarn length delivered by the yarn delivery wheel at its yarn intake side (19) to the yarn storing device (22) during yarn return operation equals the yarn length deposited in the yarn storage unit (22).
12. Yarn delivering device according to claim 1, characterised in that the drive (3) is an electric motor (5).
13. Yarn delivering device according to claim 12, characterised in that the drive (3) is a position-regulated electric motor (5).
14. Yarn delivering device according to claim 8, characterised in that the yarn laying device drive (27) is an electric motor (28).
15. Yarn delivering device according to claim 14, characterised in that the electric motor (28) is a position-regulated electric motor.
16. Yarn delivering device according to claim 1, characterised in that a yarn tension sensor (39) is arranged between the yarn delivery wheel (4) and the yarn using station.
17. Yarn delivering device according to claim 1, characterised in that the drive (3) is driven at a predetermined speed in the positive delivering operational mode at least during normal operation.
18. Yarn delivering device according to claim 17, characterised in that the predetermined speed is set to be proportional to a speed of the knitting machine.
19. Yarn delivering device according to claim 1, characterised by
    a yarn tension sensor (39) which is arranged between the yarn delivery wheel (4) and the yarn using station, and
    a control device (11) which operates the drive during normal operation in positive mode and in return operation in yarn tension regulating mode
20. Yarn delivering device according to claim 19, characterised in that the speed of the drive (3) in positive mode coincides with a predefined speed at least within the predefined limits of yarn tension.
21. Yarn delivering device according to claim 19, characterised in that the speed of the drive (3) in return operation is determined by the control device (1) with reference to the yarn tension so that the yarn tension remains as constant as possible during the return operation.
22. Yarn delivering device according to claim 1 or 19, characterised in that a dynamic yarn storage unit is provided between the yarn delivery wheel (4) and the yarn using station.
23. Yarn delivering device according to claim 1 or 19, characterised in that the yarn storage unit (22), its drive (28), the yarn delivery wheel (4) and its drive (5) are supported by a common support.
24. Yarn delivering device according to claim 23, characterised in that the drive (28) of the yarn storage unit (22) and the drive (5) of the yarn delivery wheel (4) are accommodated in a common housing.
25. Yarn delivering device according to claim 24, characterised in that in the housing a control device (11) for the drives (5, 28) is accommodated.
26. Yarn delivering device according to claim 1 or 19, characterised in that the yarn storage unit (22) comprises a rotary lever (25) which at its free outer end supports a yarn guiding means (24) and its pivot or rotary axis is arranged to be coaxial to the axis of rotation of the yarn delivery wheel (4).
27. Yarn delivering device according to claim 1 or 19, characterised in that a slip facilitating device is provided between the drive (3) and the yarn (41).
28. Method for operating a yarn delivering device (1) comprising a yarn delivery wheel (4) which comprises a yarn inlet side (19) and a storage section (17) for receiving a yarn winding, a drive (3) which is connected to the yarn delivery wheel (4) and can be operated in two opposite directions of rotation in order to deliver yarn (41) during normal operation with forwards rotation (50) in yarn delivery direction (52) to a yarn using station and in order in return operation to wind yarn back onto the yarn delivery wheel (4) returned with backwards rotation (53) from the yarn using station in return direction (54),
    a yarn storage unit (22) which is arranged in front of the yarn delivery wheel (4) relative to the yarn delivering direction (52) in order during the backwards rotation (53) to temporarily storage yarn returned from the yarn delivery wheel (4) on its yarn inlet side (19),
    a yarn tension sensor (39) which is arranged between the yarn delivery wheel (4) and the yarn using station,
    characterised in that the yarn storage unit (22) is arranged between a yarn brake (49) and the yarn delivery wheel (4) and the drive (3) is operated during normal operation in positive mode and in return operation in yarn tension control mode.

Images