EP0401516B1 - Device and method for piecing yarn in an open-end spinning machine - Google Patents

Description

The present invention relates to a device for spinning a thread on an open-end spinning device, with an open-end spinning element, a thread draw-off tube, a winding device, a feeder for feeding a thread end to the thread draw-off tube, a cutting device for defined cutting to length of the thread and a drive device for the To move feeders from a starting position over a thread take-up position and a cutting position to a thread insertion position and beyond the thread take-off tube, as well as a method for piecing a thread with the aid of such a device.

Devices for piecing are generally known. In a non-generic device, feed rolls are provided for returning the thread to the fiber collecting surface, to which a thread length measuring device can be assigned (EP-A-0 274 016). The feed rolls must slip to avoid excessive tension in the thread between the bobbin returning the thread and the feed rolls. In the case of fine threads, this can cause them to slip out of the pair of feed rollers. There the thread end is first brought into a standby position within a thread take-off tube. The distance of the thread end to the ready position can be varied depending on the diameter of the rotor used.

Slipping out of the thread is avoided by a generic device. In a known generic device (DE 3.417.331 A1) for piecing a thread, it is provided that both the feeder and the cutting device can be moved out of a rest position in order to pick up the thread, cut it to length, present it to the thread take-off tube and finally release it. The feeder and the cutting device are arranged on a slide and are movably mounted on the slide, wherein they are driven with fixed transmission ratios by one and the same drive mounted on the slide.

In practice, when other materials are spun, the spinning rotor is often exchanged for one with a different diameter. If the yarn return length is not adapted to this changed diameter of the spinning rotor (or the size of another open-end spinning element), there is a risk that the attachment will fail or the piecing cannot be tolerated. However, it is not possible to set the thread return length in the known device, since otherwise the thread can not be cut to length or the cutting device could get into the area of the thread take-off tube.

The object of the present invention is therefore to design the known device in such a way that the returned thread length can be adapted to the open-end spinning element used in each case, and to create a method which can be carried out with the aid of this device.

This object is achieved in that a thread length adjusting device is provided for determining the thread length to be returned to the open-end spinning element, that the feeder has a first stop that can be deactivated. for determining the cutting position and a second stop for determining the thread insertion position are assigned, in which the thread end is essentially above the mouth of the thread take-off tube. The first of the two stops defines the length of the thread that protrudes from the feeder as the free end of the thread, while the second stop fixes the distance of the feeder from the mouth of the thread take-off tube in such a way that, depending on the length of the free end of the thread, it essentially extends over the mouth of the thread take-off tube. This fixation of the cutting position and the thread insertion position of the feeder allows exact thread lengths to be specified, so that the exact thread length required for piecing can be set with the aid of the thread length adjusting device.

In order to be able to precisely preset the thread length to be returned, the thread length adjusting device expediently has an adjustment scale. This preferably has markings for different sizes of the open-end spinning element. It has been shown that, depending on different types of fibers, the thread length to be returned has to be of different sizes, which is why it is also advantageous if the setting scale has markings for different types of fibers.

The thread setting device can be designed differently and consequently control the thread length to be returned in different ways. According to a preferred device, the first of the two stops is adjustable and part of the thread length adjusting device. This results in a length of the thread end that corresponds to the desired thread return. If the second stop is not adjustable, it can be ensured by appropriate design of the mouth of the thread take-off tube or a corresponding air duct that even with different yarn end lengths and the same way by which the feeder is moved over the mouth of the thread take-off tube, a safe suction of the Thread end is guaranteed.

The two stops are advantageously arranged on a common support, it being expedient not only to set one stop by relative adjustment with respect to the support, but also to set both stops together by adjusting the common support.

In order not to have to adapt the feed movement of the feeder to the respective position of the second stop, the feeder is advantageously connected to its drive device via an elastic coupling member. If the feeder is stopped by running onto the second stop, the additional movement of the drive is absorbed by this elastic coupling member.

It is not absolutely necessary that the stops are adjustable. Instead of or in addition to an adjustability of the stops, the thread length adjustment device can also be connected via a control device to a drive device of a thread return device, which can be formed by the winding device or an auxiliary bobbin and its drive or also by auxiliary rollers. This makes it possible to return thread lengths that are not provided by appropriate adjustment of the stops by an adapted return delivery from the winding device into the spinning element.

The feeder can in principle be stored and moved in any manner, but arranging the feeder on a pivot axis is particularly advantageous, the carrier also being expediently arranged on this pivot axis of the feeder. According to a preferred embodiment of the subject matter of the invention, the pivot axis is arranged essentially parallel to the thread path, so that the feeder can be moved accordingly in a substantially horizontal pivot plane.

So that the feeder can be moved into the position for transferring the thread to the thread take-off tube after being cut to length, the first stop must release the feeder. This can be done in various ways, for example by a retractable counter element on the feeder. However, the first stop is advantageously adjustable transversely to the direction of movement of the feeder. In order to relieve this stop, it can be provided that the feeder can be briefly moved away from this before the first stop is withdrawn.

Usually, the thread is not only brought to a certain length, but also in a special shape that is particularly suitable for piecing. In this case, it is preferably provided that a preparation device for the thread end is arranged in the movement path of the feeder between the cutting device and the cutting position of the feeder.

In order to have defined conditions when preparing the thread end, it has proven to be expedient that a support curve is connected to the first stop, on which the preparation device is supported elastically and through which it can be brought into the area of the thread that leads to the extends in the cutting position feeder. It is also advantageous if the preparation device is pivotally mounted about the cutting device.

In order not to have to provide an excessively long cover for the draw-off tube, if the feeder can be brought into different end positions when the thread end is transferred to the draw-off tube, it is advantageously provided that the feeder is assigned a draw-off tube cover which - with respect to the feed movement of the feeder - can be held by means of an elastic element in contact with the trailing side of the feeder and can be retained in this position in relation to the movable feeder by a stop in the area of the thread take-off tube. In this way, an embodiment is made possible in which a compact exhaust pipe cover can be provided, which always stops above the exhaust pipe regardless of the feed movement of the feeder and optimizes the air flow, so that a safe suction of the thread end is ensured regardless of the respective length of the thread end and the corresponding feed movement of the feeder.

According to an advantageous embodiment, it is provided that the draw-off tube cover has a cover plate, the leading edge of which, in relation to the feed movement of the feeder, is designed as a counter-stop for the stop in the area of the thread draw-off tube. With the help of the cover plate, the air flow in the area of the mouth of the thread draw-off tube can be strengthened, so that an improved introduction of the thread end into the draw-off tube is achieved. In order to optimize this effect, it is advantageously provided that the draw-off tube cover has a bearing piece and a cover plate which is pivotably mounted thereon and which can be brought into contact with the mouth of the thread draw-off tube. It has proven to be advantageous that the cover plate is assigned a controllable drive device, which preferably has an electromagnet.

In order to be able to compensate for dimensional tolerances and to achieve optimal coverage of the outlet area of the draw-off tube in a simple manner, it is advantageous if the cover plate has on its side facing the thread take-off tube an elastic or elastically mounted sealing plate, which according to a preferred embodiment is a rigid, from which Cover plate is elastically carried sealing plate. In order to ensure that the cover plate and not the sealing plate serves as a stop, it can be provided that the cover plate projects beyond the sealing plate in the direction of the feeder.

In particular in the case of a pivotable mounting of the feeder, it is advantageous if the exhaust pipe cover, possibly by means of its bearing piece, and the feeder are pivotably mounted on a common pivot axis.

Nowadays it is customary to carry out the piecing with the aid of a maintenance device which can be moved along a large number of open-end spinning devices arranged next to one another. In this case, the feeder, the two stops assigned to it and the thread length adjusting device are expediently arranged on the maintenance device.

According to an advantageous method, it can be provided that the cutting position and the thread insertion position of the feeder are fixed to a predetermined size of the fiber collecting surface of the open-end spinning element and that different thread lengths for piecing are produced by returning or pulling off the thread. The cutting position and the thread insertion position of the feeder are preferably the smallest size of the fiber collecting surface of the open-end spinning element that can be used and the additional thread length required for larger sizes of the fiber collecting surface is provided by return delivery. In this way, the thread return delivery length can be controlled in a simple manner, for example by changing an electronic control program.

The device according to the invention and also the method according to the present invention are simple and allow a very exact adjustment of the thread length to be returned, so that defined, inconspicuous piecing with high strength can be achieved. If spinning rotors on a machine are exchanged for such other diameters - or other spinning elements with a different size of the fiber collecting surface -, an adaptation to the new diameter or the new size of the fiber collecting surface can be achieved quickly and precisely, so that the same will still be the case Piecing security is guaranteed and the piecing is also inconspicuous.

Figur 1

in perspektivischer Ansicht eine Offenend-Spinnstelle mit der erfindungsgemäßen Anspinnvorrichtung;

Figur 2

in schematischer Draufsicht die erfindungsgemäße Vorrichtung in ihren verschiedenen Arbeitspositionen;

Figur 3

in schematischer Seitenansicht eine erfindungsgemäß aus bildete Offenend-Spinnvorrichtung und eine der Spulvorrichtung zugeordnete Fadenlängeneinstellvorrichtung;

Figur 4

in der Draufsicht eine Abwandlung der in Fig. 2 gezeigten Vorrichtung in Verbindung mit einer Fadenendenpräpariervorrichtung;

Figur 5

in perspektivischer Ansicht eine abgewandelte Ausführung der erfindungsgemäßen Vorrichtung;

Figur 6

in perspektivischer Ansicht einen erfindungsgemäßen Zubringer; und

Figur 7

eine Abwandlung eines Details des in Fig. 6 gezeigten Zubringers.

Further details of the invention are explained in more detail below on the basis of several exemplary embodiments with the aid of drawings. Show it:

Figure 1

a perspective view of an open-end spinning station with the piecing device according to the invention;

Figure 2

a schematic plan view of the device according to the invention in its various working positions;

Figure 3

a schematic side view of an open-end spinning device formed according to the invention and a thread length adjusting device assigned to the winding device;

Figure 4

in plan view a modification of the device shown in Figure 2 in connection with a thread end preparation device.

Figure 5

a perspective view of a modified embodiment of the device according to the invention;

Figure 6

a feeder according to the invention in perspective view; and

Figure 7

a modification of a detail of the feeder shown in FIG. 6.

The subject matter of the invention is first explained with the aid of FIG. 1, in which only the parts necessary for understanding the invention are shown.

In an open-end spinning machine, a large number of open-end spinning devices are arranged side by side, of which only the covers 10 and 11 of two adjacent spinning positions can be seen in FIG. 1. The covers 10, 11 each cover a spinning device which, in the usual and therefore not shown, has an open-end spinning element, for example a spinning rotor, with a fiber collecting surface. The open-end spinning element is preceded by an opening device, to which a sliver is fed with the aid of a feed device. The dissolving device dissolves the sliver into individual fibers, which are fed to the open-end spinning element and are deposited there on the fiber collecting surface under the action of a suction air stream (spinning negative pressure). The fibers are bound into the end of a thread end and drawn off through a thread draw-off tube 12 with the aid of a pair of draw-off rollers 2, which in the usual way consist of a driven draw-off roller 20 and a pressure roller which rests elastically thereon 21 is formed. The drawn thread 35 is fed to a winding device 3, which has a driven winding roller 30, on which a bobbin 31 rests during the spinning operation. The bobbin 31 is carried in a known manner between two bobbin arms 32 and 33, with the aid of which the bobbin 31 can be brought into contact with the bobbin roller 30 or can be lifted off the bobbin.

An auxiliary drive device 34, which has a drivable auxiliary drive roller 340, can be delivered to the coil 31. Since auxiliary drive devices of this type are known, for the sake of clarity, the illustration of the conventional swivel drive for this and the drive device for the auxiliary drive roller 340 have been omitted.

In order to be able to suck off the resulting thread end from the bobbin 31 in the event of a thread break, a suction tube 4 which can be fed to the bobbin 31 is provided. This suction tube 4 has a mouthpiece 40 in the usual way, which extends in the receiving position near the coil 31 parallel to its surface line over the entire length of the coil 31. The suction tube 4 has on its winding device 3 and the spinning device - of which only the cover 11 can be seen - a longitudinal slot through which the thread 35 can exit the suction tube 4 when it is pivoted back into the position shown in FIG. 1 .

A centering device 41 is located in the thread path of the thread 35 emerging from the suction tube 4. In the exemplary embodiment shown, this consists of a drivable spindle with two Length sections 410 and 411 of different diameters, between which there is a circumferential groove 412. The centering device 41 is mounted on a swivel arm 413, which can be brought into different swivel positions by a swivel drive 414 about a swivel axis 415.

The length section 410 facing the swivel arm 413 has a larger diameter than the length section 411 at the free end of the centering device 41. In addition, the two length sections 410 and 411 have opposite threads. The centering device 41 can be driven selectively in each of the two directions of rotation by means of a drive 416.

A feeder 5 can be fed to the thread 35 extending from the suction pipe 4 via the centering device 41 to the bobbin 31. The feeder 5 consists essentially of a swivel arm 50 which can be swiveled about its swivel axis 52 with the aid of a swivel drive 51. At its free end facing away from the pivot axis 52, the feeder 5 has a controllable thread clamp 53 which, according to FIG. 1, consists of a clamping jaw 530 rigidly connected to the pivot arm 50 and a clamping jaw 531 movable for this purpose. A drive 532 is assigned to this clamping jaw 531, for example in the form of an electromagnet.

A stop 7 can be delivered to the feeder 5. This stop 7 is arranged on a carrier 70 and is carried by the armature of an electromagnet 71. It can be brought into the pivoting range of the feeder 5 or moved out of it and thereby rendered ineffective (see arrow P₁₄). The Carrier 70 has an adjustment slot 700, by means of which the stop 7 can be adjusted essentially parallel to the pivoting path of the feeder (arrow P 1).

A further stop 77 is assigned to the feeder 5, which in the exemplary embodiment shown in FIG. 1 is attached to the cover 11 in an unadjustable manner. As will be explained in more detail later, this second stop 77 serves to determine the thread insertion position of the feeder 5. "Thread insertion position" is understood to mean the position of the feeder 5 in which the end of the thread 35 is located above the mouth of the thread take-off tube 12 and can be introduced into this.

In the thread path between the end of the longitudinal slot of the suction tube 4 facing away from the bobbin 31 and the centering device 41, a cutting device 8 is provided in such a way that a thread 35 can be cut off on the side of the thread clamp 53 facing away from the bobbin 31. According to the exemplary embodiment shown in FIG. 1, the cutting device 8 consists of a roller 80, which serves as an anvil and with which a cutting edge 81 cooperates, for which purpose a drive 82 is assigned. For illustrative reasons, the cutting device 8 in FIG. 1 has been shown somewhat rotated relative to the correct representation according to FIG. 2.

1, the cutting position of the feeder 5 is determined by the abovementioned stop 7. The cutting position should be understood to mean the position of the feeder 5 in which the thread end extending into the suction pipe 4 the thread 35 connected to the bobbin 31 is cut off. The adjustable in the direction of arrow P 1 or opposite stop 7 determines in this way the length of the thread end protruding from the thread clamp 53, which is produced by cutting by means of the cutting device 8. If the angular distance - based on the pivot axis 52 of the feeder 5 - between the stop 7 and the cutting device 8 is larger, the free thread end generated is correspondingly longer, while it becomes shorter with a smaller angular distance.

Corresponding drive and control elements are of course assigned to the individual elements described, which can be designed in a generally customary manner and are therefore not shown in the figures for the sake of clarity. The drive and control elements are controlled by a control device 96 (see FIG. 3) which also controls the entire piecing process.

After the construction of the device has been described, its function will now be explained in more detail:

During normal spinning operation, the thread 35 spun in the usual manner in the spinning device is fed with the aid of the draw-off roller pair 2 to the bobbin 31 driven by the winding roller 30 and wound onto it, the thread 35 in the usual way by thread tension compensation means (not shown) under constant tension is held and is oscillated by a traversing thread guide, not shown.

If a yarn breakage occurs, the open-end spinning device is shut down in a known manner, so that no more fibers get onto the fiber collecting surface of the open-end spinning element. In addition, the bobbin 31 is lifted from the winding roller 30 with the aid of known means and therefore not shown, so that the bobbin 31 is also stopped.

To re-spin the thread 35, the open-end spinning element is cleaned in a known manner, which is usually braked temporarily, possibly even to a standstill.

In order to be able to return the end of the torn thread 35 from the bobbin 31 of the winding device 3 to the fiber collecting surface of the open-end spinning element, this end must be pulled off the bobbin again. For this purpose, the auxiliary drive roller 340 of the auxiliary drive device 34 is then delivered to the bobbin 31 lifted off the winding roller 30. The auxiliary drive roller 340 is now driven with the aid of conventional means (for example drive motor 342 - see FIG. 3) opposite to the normal winding direction. In addition, the suction pipe 4 is pivoted against the coil 31 and a negative pressure is generated in it, in accordance with the feed movement of the auxiliary drive device 34. The thread end is thus sucked into the suction pipe 4. After a sufficient length of the thread 35 has entered the suction tube 4 so that it is held securely by the suction air flow prevailing here, the suction tube 4 is pivoted away from the spool 31, the thread 35 leaving the suction tube 4 through its longitudinal slot with its however, the free end is still held in the intake manifold 4. The thread 35 leaving the suction pipe 4 arrives on exiting from the suction pipe 4 to the centering device 41, which is then driven so that the thread 35 reaches its circumferential groove 412. The thread 35 thus assumes a defined thread path between the slot end facing away from the bobbin 31 and the centering device 41.

The feeder 5 is initially in an initial position 5a (FIG. 2), from which it is pivoted into the position shown in FIG. 2 by a solid line, its cutting position. The thread clamp 53 passes the thread path (see thread 35a), grips and clamps the thread 35 between its clamping jaws 530 and 531, which may possibly first be opened to grip the thread 35 and closed again after the thread 35 has been picked up. The feeder 5 is then pivoted further in the direction of arrow P₂ until it hits the stop 7 and thus reaches its cutting position. During this movement, the thread 35 extending from the slot end of the suction tube 4 to the thread clamp 53 passes the cutting device 8. If the feeder 5 is in position against the stop 7, i.e. reached its cutting position, the cutting device 8 is actuated and the thread 35 is cut, which thus has a defined thread length L between the thread clamp 53 and the cutting device 8.

After the thread 35 has been brought to its defined thread length L, the feeder 5 must be moved further to the open-end spinning device (see cover 11). For this purpose, the stop 7 is withdrawn from the swivel path of the feeder 5. In order not to have to use large driving forces for this purpose, the feeder 5 is first shown in FIG Direction of arrow P₃ slightly removed from the stop 7 before it is pulled away from the pivot path of the feeder 5. Then the feeder 5 is pivoted in the direction of the arrow P₄ to the stop 77 in its thread insertion position 5b, the thread clamp 53 being moved over the mouth of the thread take-off tube 12.

In relation to the arrow P₄ there are two guides 110 and 111 in front of the mouth of the thread take-off tube 12. When the feeder 5 moves into its end position 5b, the thread 35 is guided between the two guides 110 and 111, thereby ensuring that the thread 35 reaches the area of the suction air flow prevailing in the thread take-off tube 12 due to the spinning vacuum.

The position of the stop 77 is determined such that the end of the thread 35 in the thread insertion position 5b of the feeder 5 is substantially above the mouth of the thread take-off tube 12 and is sucked into it by the suction air flow effective there. The feeder 5 now returns in the direction of the arrow P₅ and remains in the transfer position 5c above the thread take-off tube 12. The thread clamp 53 (FIG. 1) is opened so that the thread 35 is released from the feeder 5. The thread 35 is now sucked onto the fiber collecting surface of the open-end spinning element, not shown, where it lies on the fibers that have been fed back in again. The thread take-off now starts again in a manner known per se and the thread 35 is wound onto the bobbin 31, which has meanwhile been lowered again onto the winding roller 30. By appropriate drive of the centering device 41 opposite to the previous direction of rotation, which was required for centering the thread 35, the thread 35 is now moved over the length section 411 to its free end and thrown off.

Since the thread 35 takes different lengths in relation to the centering device 41 when it moves from the take-over position (see thread 35a) to the thread insertion position 5b of the feeder 5, it is necessary to compensate for these path differences. This is done by correspondingly pivoting the centering device in the direction of the double arrow P₆, which is accomplished with the help of the swivel drive 414.

As shown in Fig. 1, the stop 7 is adjustable substantially parallel to the pivot path of the feeder 5 (see arrow P₁). This adjustability serves the purpose of being able to adapt the free thread end to different sizes of the fiber collecting surface. Furthermore, this adjustability of the stop 7 enables an adaptation to different fiber materials which differ with regard to the stack length of the fibers or also with regard to whether they are smooth or crimped. This will be explained in more detail later in connection with FIG. 4.

As FIG. 1 clearly shows, the stop 77 is not adjustable in this embodiment. In this case, the stop 77 is firmly adjusted to match the smallest possible size of the fiber collecting surface, for example the diameter of a spinning rotor. The fixedly adjusted stop 77 is thus used for fixing a basic length of the thread 35 to be returned to the open-end spinning element.

If longer thread lengths are required for the return delivery to the fiber collecting surface of the open-end spinning element, the additional thread length is determined with the aid of a thread length adjusting device 9. According to the exemplary embodiment shown in FIG. 3, this additionally required thread length is provided after the free end of the thread 35 has been introduced into the thread take-off tube 12 by returning the thread 35, which is brought about by turning the auxiliary drive roller 340 back by a defined distance (circumferential area). For this purpose, according to FIG. 3, a drive motor 342 is provided for driving the auxiliary drive roller 340, which drive motor is driven in a suitable manner, e.g. a belt overdrive, not shown, connected to the auxiliary drive roller 340. The drive motor 342 is connected via a control line 343 and the already mentioned control device 96 to the thread length adjustment device 9, which has an adjustment button 90 and an adjustment scale 91. By turning the adjusting knob 90 in the direction of the arrow P₇ or P₈ the aforementioned additional required return quantity of the thread 35 can thus be determined. This setting ensures that the auxiliary drive roller 340 is rotated more or less in the unwinding direction of the bobbin 31 and accordingly provides a larger or smaller additional thread length.

In this exemplary embodiment, the thread length to be returned is shared by the stop 77 and the auxiliary drive roller 340 is determined, this length being determined by the adjusting knob 90 of the thread length adjusting device.

Instead of the thread 35 being returned by the bobbin 31 of the winding device 3, a special piecing spool (not shown) can also be provided, from which the thread 35 to be spun is unwound. In this case, the thread length adjustment device 9 can be assigned to this piecing bobbin. However, it can also be provided that the return of the thread takes place with the aid of auxiliary rollers (not shown), to which the thread length adjusting device 9 can then optionally be assigned.

In the above-mentioned embodiment, the first stop, i.e. the stop 7, adjustable and thus determines the basic length of the thread length to be returned for spinning onto the fiber collecting surface of the open-end spinning element. In addition, the adjusting knob 90 of the thread length adjusting device 9 also serves to adjust the thread length to be returned to the fiber collecting surface during the piecing process, so that the adjustable stop 7 is also part of the thread length adjusting device.

FIG. 4 shows a modification of the device shown in FIG. 1, in which the two stops 7 and 72 for the feeder 5 are carried by a common carrier 73. This carrier 73 has the shape of a plate.

With the help of the carrier 73, an exact relative arrangement of the two stops 7 and 72 to each other is possible. This is special Significance if the elements that are only required for piecing are not arranged separately at each spinning station for each open-end spinning device, but together for a large number of spinning stations of an open-end spinning machine that are arranged next to one another on a maintenance device 15, which runs along the spinning machine 1 - Of which only the covers 10, 11 and 16 of three open-end spinning devices can be seen in FIG. 2 - can be moved. Thus, the two stops 7 and 72 shown in FIG. 4 with their carrier 73, but also the feeder 5 in its entirety and the thread length adjusting device - regardless of their special design - are arranged on this maintenance device 15.

According to the embodiment shown in Fig. 4, the carrier 73 is part of this thread length adjusting device and for this reason rotatably mounted on the pivot axis 52 of the feeder 5, so that both stops 7 and 72 are adjusted together by adjusting the plate-shaped carrier 73 without this however, the angular distance between the stops 7 and 72 changes. By adjusting the position of the stop 7 (see position 7a) for the cutting position of the feeder 5, the position of the stop 72 for the thread insertion position of the feeder 5 is also automatically changed (see position 72a). In this way it is achieved that in any case the distance between the thread clamp 53 and the cutting device 8 on the one hand, which determines the length of the free thread end, and the thread clamp 53 and the thread take-off tube 12 (see FIGS. 1 and 2) with certainty always the same is great.

Since the carrier 73 is not adjusted linearly but by rotation, the adjustment slot 730 is also bent accordingly. A bolt 731 extends through the adjustment slot 730 and is suitably held stationary. The bolt 731 has a thread at its free end, onto which a wing nut 732 is screwed. After loosening the wing nut 732, the carrier 73 can thus be adjusted with the stops 7 and 72 and then secured again in the set position by tightening the wing nut 732 again.

1 and 2 show, it is not absolutely necessary that the second stop 77 is adjustable, since differences between the distance between the thread clamp 53 of the feeder 5 in the cutting position and the cutting device 8 on the one hand and the distance between the Thread clamp 53 of the feeder 5 in the thread insertion position 5b and the mouth of the thread take-off tube 12, on the other hand, can be compensated for by appropriate control of the bobbin 31 in the unwinding or also in the winding direction. This is all the more true if the first stop 7 is connected to the control device 96 (FIG. 3) in such a way that the current position of the stop 7 is sensed and the control device 96 is reported, which position of the stop 7 is in control of the Auxiliary drive roller 340 - taking into account the setting of the adjusting knob 90 - considered.

If the stop 77 is not adjustable, it is in the preferred embodiment of the device described in the position which corresponds to the smallest size of the fiber collecting surface, otherwise, for example by a compressed air nozzle (not shown) attached to the feeder 5 and oriented in the direction of the arrow P₅ (not shown) would have to be ensured by its design and / or orientation that the free end of the thread 35 during the return movement of the feeder 5 from the thread insertion position 5b in its transfer position 5c it really comes into the sphere of influence of the air flow effective in the thread take-off tube 12.

However, it is also not an unconditional requirement that the first stop 7 can be adjusted, since the thread length required for piecing is then changed solely by adjusting the adjusting knob 90.

If none of the stops 7 and 77 is adjustable, they are in a position that corresponds to the smallest size of the fiber collecting surfaces of the open-end spinning element that are used. As already discussed above, any additional thread length required is turned back by turning the winding device 3 or else by return delivery from a special piecing spool (not shown), e.g. with the aid of auxiliary conveyor rollers (also not shown).

If the stops 7 and 77 are not set to the smallest size of the possible fiber collecting surface sizes, but instead deviate therefrom, the resulting differences in the thread length required for piecing are made by correspondingly turning the bobbin 31, a special piecing bobbin and / or special auxiliary conveyor rollers in the unwinding or in the winding direction.

As open-end spinning elements, spinning rotors, electrostatically operating elements, friction spinning elements of various shapes and purely pneumatically operating elements come into question. In the latter case, the binding area in the air flow is to be understood as equivalent to the fiber collecting surface.

In order to precisely adjust the adjustment to a given size of the fiber collecting surface, e.g. to a given rotor diameter, the carrier 73 has an adjustment scale 92 with which a stationary pointer 93 cooperates. The adjustment scale 92 has markings in the form of graduations 920, which define certain sizes of the fiber collecting surface, e.g. Rotor diameter, mark. In addition, according to the exemplary embodiment shown in FIG. 4, the tick marks 920 are assigned even smaller markings in the form of tick marks 921 for setting different types of fibers, which allow a deviation from the basic setting defined by the tick marks 920 in adaptation to different types of fibers.

With normal fiber material, the carrier 73 is set so that the pointer 93 points to the graduation 920, which corresponds to the size of the fiber collecting surface, for example the diameter of the spinning rotor, which is currently used on the open-end spinning device in question. If the fiber material deviates from the normal values in terms of its fiber length or its tendency to curl upwards or downwards, the carrier 73 is adapted to the fiber material is adjusted from this position corresponding to the fiber collecting surface by one or more graduation marks 921 in one or the other direction.

As FIG. 5 shows, the setting scale does not necessarily have to have different graduations 920 and 921 for the size of the fiber collecting surface and for the fiber material. It may be enough also a scale without subdivision or only with references either to the size of the fiber collecting surface or to the fiber material.

It is often desirable that the thread 35 to be inserted into the thread take-off tube 12 is not only brought to a defined length, but also has a tapering shape. For this purpose, a preparation device 83 is provided for the thread end in the exemplary embodiment shown in FIG. 4. The arrangement must be such that the preparation device 83 is in the vicinity of the thread path when the feeder 5 is in contact with the stop 7. 4 is in the path of movement of the feeder 5 between the cutting device 8 and the thread clamp 53 which is in contact with the stop 7, i.e. in the cutting position, the feeder 5.

As shown in Fig. 4, the thread path changes when the stop assumes different positions. If the stop 7 is in its position 7a, for example, the thread 35 between the thread clamp 53 and the cutting device 8 assumes the position 35b. This position would change if unchanged Position of the preparation device 83, the thread 35 held stretched is no longer in the mouth region of the preparation device 83. In order to avoid this disadvantage, it is provided according to FIG. 4 that the preparation device 83 is mounted on a swivel arm 84, the swivel axis 85 of which is in the region of the cutting device 8. The swivel arm 84 with the preparation device 83 is held in elastic contact with a support curve 733, which is formed on the support 73 for the stop 7, with the aid of a tension spring 86, which is anchored on the one hand in the support 73 and on the other hand on the swivel arm 84. This support curve 733 has such a shape that when the carrier 73 is adjusted, the preparation device 83 is always brought into the thread path corresponding to the position of the stop 7 by the action of a tension spring 86. In this way it is ensured that the end of the thread 35, which is produced by cutting with the aid of the cutting device 8, is always located above the preparation device 83 and can therefore also be safely introduced into it and prepared there in the desired manner.

In principle, the preparation device 83 can be mounted as desired. For example, it is also possible to arrange them in a sliding manner in a link arranged radially to the pivot axis 52. Since the thread path of the thread 35 extending to the feeder 5, when the feeder 5 is in its cutting position in abutment with the stop 7, depends on the position of the stop 7, the support curve 733 with the stop 7 (in the exemplary embodiment shown above the Carrier 73) connected.

The thread 35 is also introduced into the preparation device 83 can, if desired, be carried out with the aid of a suction air flow effective in the preparation device 83 or also with the aid of a compressed air flow directed against the preparation device 83, a corresponding compressed air nozzle possibly also being provided on the feeder 5.

The subject matter of the invention can be modified in a variety of ways, e.g. by replacing individual features with equivalents and through other combinations thereof. For example, it is not necessary for the support 73 to be assigned an adjustment scale 92, but such an adjustment scale 92 enables particularly rapid adjustment. However, it is also conceivable that a digital thread length adjusting device is provided on the control device 96, which automatically adjusts the support 73 and thus the stops 7 and 72 after input or setting of corresponding numerical values.

1, an embodiment of the feeder 5 was explained, which is pivotally mounted about a pivot axis 52 which is oriented substantially parallel to the more or less vertical thread path, ie about a pivot axis 52 which is arranged essentially vertically. This enables a particularly simple design of the suction pipe 4 and thus also a particularly secure feeding of the thread 35 to the feeder 5. With a correspondingly modified design of the suction pipe 4, however, it is not absolutely necessary for the feeder 5 to be pivoted about a vertical pivot axis 52. Fig. 5 shows a modification of the device in which the pivot axis 54 of the feeder 5 is arranged horizontally. The feeder 5 has In this embodiment, a cranked swivel arm 55, at the free end of which there is a thread clamp 56, which has a first clamping jaw 560, which is an integral part of the swivel arm 55, and a second clamping jaw 561, which is movable for this purpose, and which is assigned a drive 562.

The feeder 5 can be moved in the direction of the arrow P₈ into its transfer position and into its end position (not shown), which is why the thread clamp 56 is funnel-shaped in relation to this direction of movement (arrow P₈) and can also be opened to the front.

At the free end, the swivel arm 55 has a stop 57 which is in contact with the stop 7 in the cutting position of the feeder 5, in which the thread 35 is separated by the cutting device 8.

The stop 7 and a stop 74 for determining the thread insertion position (compare thread insertion position 5b in FIG. 2) are mounted on a common carrier 75, which is an essential part of a thread length adjustment device. For this purpose, the carrier 75 is fastened to a stationary holder 76 in such a way that the carrier 75 can be adjusted in the direction of the double arrow P₉ in one direction or the other parallel to the direction of movement (see arrow P₈) of the feeder 5. For this purpose, the carrier 75 has an adjustment slot 750, through which a bolt 760 carried by the holder 76 extends, onto which a nut 761 can be screwed and thus secures the carrier 75 on the holder 76.

According to FIG. 5, the carrier 75 in turn has an adjustment scale 94 with which a pointer 95 carried in a stationary manner cooperates. It is thus in turn possible to set the position of the carrier 75 exactly in accordance with the respective requirements.

If a thread break occurs, the thread 35 unwound from the bobbin 31 or a piecing spool also passes into the suction tube 4, from which it emerges after the suction tube 4 has been pivoted back through a slot 42, the thread 35 reaching the centering device 41. The end of the slot 42 of the suction pipe 4 is shown in broken lines in FIG. 5. The thread 35 is now on a defined thread path between the end of the slot 42 and the circumferential groove 412 of the centering device 41.

The feeder 5 is initially in a starting position, not shown, which — in relation to the illustration in FIG. 5 — is to the right of the position shown. By moving the feeder 5 in the direction of the arrow P₈, the thread 35 passes between the two clamping jaws 560 and 561 of the thread clamp 56.

The clamping jaws 560 and 561 can be open during the take-up of the thread 35 and can be closed after the take-up of the thread 35. However, it is also possible to leave the clamping jaws 560 and 561 in mutual elastic contact even during the take-up of the thread 35 if the thread 35 is securely picked up by appropriate selection of the clamping pressure and by appropriate design of the clamping jaws 560 and 561. This also applies to the thread clamp 53 described above.

The feeder 5 continues its pivoting movement about the pivot axis 54 until its stop 57 comes to rest against the stop 7 preset with the aid of the carrier 75. Here, the thread 35 is brought between the roller 80 and the cutting edge 81 of the cutting device 8. When the feeder 5 is in this cutting position, the cutting device 8 is actuated so that the thread end protruding from the thread clamp 56 has a defined length 1 preset by setting the stop 7 with the aid of the carrier 75. After the thread 35 has been cut to length, the stop 7 is moved away from the path of movement of the feeder 5, in particular its stop 57, the feeder 5 possibly also being moved slightly opposite to the direction marked by the arrow P₈. Then the feeder 5 is pivoted further in the direction of the arrow P₈ until its stop 57 comes to rest against the stop 74. The position of the stop 74 is fixed on the carrier 75 so that when the feeder 5 is in contact with the stop 74, i.e. is in its thread insertion position, the thread end in this position of the feeder 5 ends above the mouth of the thread take-off tube 12. After the stops 7 and 74 have been adjusted jointly, this applies in every position of the carrier 75.

The thread end is now sucked into the thread take-off tube 12, wherein corresponding guide elements can be provided in the area of the mouth of the thread take-off tube 12 (see guides) 110 and 111 in Fig. 1). The feeder 5 is then moved back until the thread clamp 56 is above the mouth of the thread take-off tube 12. By actuating the drive 562, the thread clamp 56 is opened so that the thread 35 can be sucked into the thread take-off tube 12. The actual piecing back delivery down to the fiber collecting surface can take place in the usual way, for example by throwing off the thread 35 from a previously formed thread reserve (not shown). After the thread 35 has been released by the thread clamp 56, the feeder 5 returns to its starting position.

If after cutting and possibly preparing the thread 35 by continuing the pivotal movement of the feeder 5 with its end in the area of the mouth of the thread take-off tube 12, it is important that the thread 35 is exposed to such a strong suction air flow that it is safe is held. For this purpose, the thread take-off tube 12 has a specially designed mouthpiece 13 (see FIG. 6). The mouthpiece 13 has a slot 130 extending from the mouth of the thread take-off tube 12 in the direction of the arrow p 1, the side walls of which form a guide for the thread 35.

The mouthpiece 13 also has on its side facing away from the thread take-off tube 12 a sealing surface 131, on which a take-off tube cover designed as a cover plate 60 can be placed. The cover plate 60 is part of a swivel arm 6, which is mounted together with the feeder 5 on one and the same swivel axis 52. While the pivot arm 50 of the feeder 5 axially secured on the pivot axis 52 in a manner not shown is, the pivot arm 6 is axially movable on the pivot axis 52. For this purpose, a spring support disk 520 is provided according to FIG. 6 at the upper end of the pivot axis 52. Between this spring support disc 520 and the swivel arm 6, a compression spring 521 is arranged which acts on the swivel arm 6 in the direction of the swivel arm 50, ie in the direction of the arrow P 1. The mouthpiece carries - with respect to the direction given by the arrow P₁₀ - a ramp ramp 132, while the swivel arm 6 in the region of its cover plate 60 on its leading side - with respect to the arrow P₁₀ - on its bottom side facing the mouthpiece 13 a corresponding ramp (not shown).

The mouthpiece 13 carries at its outlet end - with respect to the arrow P₁₀ - a stop 14 against which the swivel arm 6 can be brought to rest.

The swivel arm 6 has on its - with respect to the feed movement of the feeder 5 marked by the arrow P₁₀ - leading side a stop 600 with which it can be held in contact with the trailing side of the swivel arm 50 of the feeder 5. For this purpose, according to the exemplary embodiment shown, an elastic element designed as a tension spring 61 is provided, one end of which is attached to the swivel arm 50 and the other end of which is attached to the swivel arm 6.

On the side of the swivel arm 50 facing away from the swivel arm 6, a drive lever 59 is mounted on the swivel axis 52, which carries a stop 590, on which the swivel arm 50 abuts is held with the aid of an elastic coupling member, for example a spring 591, one end of which is attached to the swivel arm 50 and the other end of which is attached to the drive lever 59. The drive lever 59 thus forms a drive device for the feeder 5, ie for its swivel arm 50.

A drive pinion 592, which is an integral part of the drive lever 59, is also mounted on the pivot axis 52. With the drive pinion 592, a rack 593 is engaged, which can be driven in the direction of the double arrow P 12 by drive means, not shown.

In the device shown in FIG. 6, the swivel arm 50 of the feeder 50 is not driven directly by the drive lever 59, but rather via the elastic coupling member (spring 591). First, the swivel arm 50 is in contact with the stop 590 of the drive lever 59, while the swivel arm 6 with its stop 600 is in contact with the swivel arm 50.

For the defined cutting of the thread 35, the swivel arm 50 is brought into contact with the stop 7 (see FIGS. 2 and 4). After the thread 35 has been cut to length and prepared, the drive lever 59 moves further in the direction of the arrow P₄ (see FIG. 2). When the swivel arm 60 reaches the ramp ramp 132 of the mouthpiece 13 and slides on the sealing surface 131, the swivel arm 60 is removed from the swivel arm 50 against the action of the compression spring 521 in the axial direction opposite to the arrow P₁₁. If the swivel arm 6 with its cover plate 60 is above the mouth of the thread take-off tube 12, it will be in this Position held back by running its leading edge on the stop 14 relative to the advancing feeder 5 (swivel arm 50), since this - in relation to the feed movement of the feeder 5 - leading edge is designed as a counter-stop for the stop 14.

The drive lever 59 continues its movement and now only takes the swivel arm 50 with it, since the swivel arm 6 is retained. Finally, the swivel arm 50 reaches the stop 77 and is in turn held back here, while the drive lever 59 continues its movement slightly. The additional movement which the drive lever 59 executes with respect to the swivel arm 50 is based on the fact that the movement generated by the movement of the rack 593 cannot be matched to the required swivel path as precisely as would be desirable for an optimal function. For this reason, the pivoting movement caused by the rack 593 is chosen to be greater than the maximum pivoting movement required for the pivoting arm 50; furthermore, for the reason mentioned, the swivel arm 50 of the feeder 5 is not rigid with the drive lever, but is only connected via an elastic coupling member.

Then when the rack 593 is reversed in its direction of movement, the drive lever 59 comes with its stop 590 back into contact with the swivel arm 50 and moves it in the opposite direction to the arrow P₁₀, the end of the thread 35 now being sucked into the thread take-off tube 12. When the swivel arm 50 runs onto the swivel arm 6, it moves it away from the stop 14, so that the thread clamp 53 lies exactly over the mouth of the thread take-off tube 12 can reach where the thread 35 is released for return delivery to the fiber collecting surface of the open-end spinning element.

The thread 35 is then drawn off in the usual way, and if it is a thread drawn off from a piecing bobbin, it is transferred to the winding device 3 in a manner known per se.

In Fig. 6, the drive for the movable jaw 531 has been omitted for the sake of clarity.

After the thread 35 has been released, the device shown in FIG. 6 returns to its starting position (compare starting position 5a in FIGS. 2 and 4).

FIG. 7 shows a modification of the swivel arm shown in FIG. 6. According to this exemplary embodiment, a bearing piece 62 designed as a pivot arm is fastened in an axially secured manner on the pivot axis 52 (see FIG. 6). On the bearing piece 62, a cover plate 64 is mounted via a joint 63, the leading edge (in relation to the feed movement of the feeder 5) is designed as a counter-stop to the stop 14. In order to pivot the cover plate 64 relative to the bearing piece 62 in order to bring the cover plate 64 into contact with the mouth piece 13 of the thread take-off tube 12, a controllable drive device - in the exemplary embodiment shown in the form of an electromagnet 65 - is provided which is removed from the bearing piece 62 by means of a bearing 620 is carried and its anchor 650 with one supported by the cover plate 64 Camp 640 is connected. The electromagnet 65 is connected via lines 651 to a control device, not shown.

It is not absolutely necessary to connect the electromagnet 65 at its two ends to the bearing piece 62 or the cover plate 64. It is sufficient to arrange the electromagnet 65 either on the bearing piece 62 or the cover plate 64 and the counter element, which is formed by the cover plate 64 or the bearing piece 62 depending on the arrangement of the electromagnet 65, by means of a spring or the like. to keep in constant contact at the free end of anchor 650.

As an alternative to the electromagnet 65, another drive device can of course also be provided, for example one which is controlled by the cover plate running onto the stop 14 via a linkage - as a result of the run-up movement.

The bearing piece 62, similar to the swivel arm 6 shown in FIG. 6, has a lateral stop 600, with which the bearing piece 62 can be held for contact with the swivel arm 50 of the feeder 5, not shown in FIG. 7. An elastic or elastically mounted sealing plate 641 is provided on the cover plate on its side facing the mouthpiece 13, not shown.

In the elastically mounted sealing plate 641 shown, four threaded bores are provided, into which screws 642 are screwed. The heads of the screws 642 serve as a stop and determine the maximum distance between sealing plate 641 and cover plate 64. A fifth screw 643 in the middle between the screws 642 serves as a guide for a compression spring 644, which is supported on the one hand on the cover plate 64 and on the other hand on the sealing plate 641 and always keeps this at a distance from the cover plate 64.

The rigid, carried by the cover plate 64 sealing plate 641 does not extend as far as the cover plate 64, which cooperates with the stop 14, in the exemplary embodiment shown, with respect to the direction of movement indicated by the arrow P 1. The cover plate thus projects beyond the sealing plate 641 in the direction of the leading feeder 5, so that the mobility of the sealing surface 641 is not impaired even after the cover plate 64 has hit the stop 14.

If the feeder in the direction of arrow P₄ (see Fig. 2) is brought into its end position (see 5b in Fig. 2), the cover plate 64 with the sealing plate 641 is attracted by the electromagnet 65, so that the sealing plate 641 at this Movement does not come into contact with the mouthpiece 13. Has the cover plate 64 reached the stop 14, the electromagnet 65 is actuated, whereby the cover plate 64 is pivoted in the direction of arrow P₁₃ and with its sealing plate 641 comes to rest on the sealing surface 131 of the mouthpiece 13. This therefore does not require a ramp ramp 132 like the mouthpiece 13 shown in FIG. 6.

Due to the elastic mounting of the sealing plate 641 can adjust them exactly to the sealing surface 131, the heads of the screws 642 emerging from the surface of the cover plate 64 visible in FIG. 7.

The end of the thread 35 is in this position of the cover plate 64 in the slot 130 of the mouthpiece 13, which is ensured due to the formation of this slot 130 and the sealing plate 641 that the air is only opposite to the direction of the arrow P₁₀ (see Fig. 6) can be sucked into the thread take-off tube 12. This suction air sucks the end of the thread 35 into the thread take-off tube 12. After the swivel arm 50 has come to rest against the stop 77 (FIGS. 1, 2 and 6), 72, (FIG. 4) or 74 (FIG. 5) had been moved further, finally, the suction air pulls thread, so that finally, after release of the mouthpiece 13 by the sealing plate 641, the train acting on the thread 35 is so great that the thread 35 even after being released by the thread clamp 53 is held securely in the thread take-off tube 12.

In the exemplary embodiments shown, the feeder 5 is always mounted on a pivot axis 52 (see FIGS. 1 to 4, 6 and 7) or 54 (see FIG. 5). However, it goes without saying that the feeder 5 can also be mounted on a carriage (not shown) which can be displaced along a straight or curved guideway.

In the exemplary embodiments described with reference to FIGS. 6 and 7, the feeder 5 (swivel arm 50) and the swivel arm 6 (FIG. 6) or the bearing piece 62 (FIG. 7) are always on a common one Pivot axis 52 mounted. It is understood that with a horizontal arrangement of the pivot axis 54 for the feeder 5, a corresponding arrangement of the pivot arm 6 or the bearing piece 62 - with corresponding design adaptation - on the same pivot axis 54 is also possible, as well as then a common support for the two stops 7 and 74 can be provided.

If the feeder 5 is displaceable in a backdrop, it is also possible to provide a correspondingly displaceable part with the cover plate 60 or 64 instead of the swivel arm 6, the movement of which is coupled to a stop corresponding to the stop 14 until it runs up.

If a common carrier 73 or 75 is provided for the two stops 7 and 72 (FIG. 4) or 7 and 74 (FIG. 5), this can be mounted independently of the feeder 5. As shown in FIG. 4, an arrangement of carrier 73 and feeder 5 on one and the same pivot axis 52 or 54 - regardless of whether it is arranged vertically according to FIG. 4 or horizontally according to FIG. 5 - is particularly advantageous since compact and simple design enables a particularly safe and precise setting of the two stops.

In the exemplary embodiments described, the first stop 7 is pulled vertically out of the essentially horizontal pivoting paths of the feeder 5 so that it can be pivoted into its thread insertion position 5b. Of course, other training courses are also possible. For example, the the first stop 7 remain unchanged in place and a counter stop provided on the feeder 5 (not shown) is actuated in order to pull it away from the area of the stop 7. It is also possible, for example, to provide a type of gear (not shown), the axis of which is arranged transversely to the path of movement of the feeder 5 and the teeth of which serve as stops for the feeder 5. The stop is activated by locking the gearwheel, while the feeder 5 is also released by releasing the gearwheel and can thus continue its pivoting movement.

The cutting device 8 operates according to the embodiment shown in the manner of a hatchet-anvil device, but other designs, e.g. like scissors, quite possible.

The thread length compensation when transferring the feeder 5 from the cutting position into the thread insertion position takes place in the described embodiment by pivoting the centering device 41, but it goes without saying that in addition or instead of the pivoting movement of the centering device 41, a correspondingly designed thread guide curve can also be provided.

Claims (29)

1. A device for piecing a yarn on an open end spinning device, with an open end spinning element, a yarn take-off tube (12), a winding device (3), a feeder (5) for supplying a yarn end to the yarn take-off tube, a cutting device (8) for cutting the yarn to a defined length and a driving device to move the feeder from a rest position (5a) via a yarn take-up position and a cutting position beyond the yarn take-off tube into a yarn introduction position (5b), characterised in that a yarn length adjusting device (9) is provided for determining the yarn length (1) to be returned into the open end spinning element, the feeder (5) being allocated a first stop (7) which can be brought out of action, for determining the cutting position, and a second stop (77, 72, 74) for determining the yarn introduction position (5b).
2. A device according to claim 1, characterised in that the yarn length adjusting device (9, 73, 75) has an adjustment scale (91, 92, 94).
3. A device according to claim 2, characterised in that the adjustment scale (91, 92, 94) has markings (920) for various sizes of the open end spinning element.
4. A device according to claim 2 or 3, characterised in that the adjustment scale (91, 92, 94) has markings (921) for various types of fibre.
5. A device according to one or more of claims 1 to 4, characterised in that the first (7) of the two stops is adjustable and is part of the yarn length adjusting device (73, 75).
6. A device according to one or more of claims 1 to 5, characterised in that the two stops (7, 72; 7, 74) are arranged on a common carrier (73, 75).
7. A device according to claim 6, characterised in that the stops (7, 72; 7, 74) can be adjusted by adjusting the common carrier (73, 75).
8. A device according to one or more of claims 1 to 7, characterised in that the feeder (5) is connected via a resilient coupling member (591) to its driving device (59).
9. A device according to one or more of claims 1 to 8, characterised in that the yarn length adjusting device (9) is connected via a control device (96) to a driving device (342) of a yarn returning device.
10. A device according to one or more of claims 1 to 9, characterised in that the feeder (5) is mounted on a pivot pin (52, 54).
11. A device according to claim 10, characterised in that the carrier (73, 75) is also arranged on the pivot pin (52, 54) at the same time.
12. A device according to claim 10 or 11, characterised in that the pivot pin (52) is arranged substantially parallel to the yarn travel.
13. A device according to one or more of claims 1 to 12, characterised in that the first stop (7) is movable transversely to the direction of movement of the feeder (5).
14. A device according to claim 13, characterised in that the feeder (5) can be moved away from the first stop (7) before the pull back of the first stop (7).
15. A device according to one or more of claims 1 to 14, characterised in that a preparing device (83) for the yarn end is arranged in the path of movement of the feeder (5) between the cutting device (8) and the cutting position of the feeder (5).
16. A device according to claims 5 and 15, characterised in that to the first stop (7) there is a connected a supporting cam (733) on which the preparing device (83) rests resiliently and through which it can be brought into the yarn region extending to the feeder (5) located in the cutting position.
17. A device according to claim 15 or 16, characterised in that the preparing device (83) is pivotally mounted round the cutting device (8).
18. A device according to one or more of claims 1 to 17, characterised in that the feeder (5) is allocated a take-off tube covering which - with respect to the supply movement of the feeder (5) - can be kept in contact on the trailing side of the feeder (5) by means of a resilient element (61) and can be retained in this position relative to the feeder (5), which is capable of moving on, by a stop (14) in the region of the yarn take-off tube (12).
19. A device according to claim 18, characterised in that the take-off tube covering has a covering plate (60, 64) of which the leading edge - with respect to the supply movement of the feeder (5) - is constructed as a counter stop for the stop (14) in the region of the yarn take-off tube (12).
20. A device according to claim 18 or 19, characterised in that the take-off tube covering has a mounting member (62) and a covering plate (64) which is pivotally mounted thereon and can be brought into contact with the orifice of the yarn take-off tube (12).
21. A device according to claim 20, characterised in that the covering plate (64) is allocated a controllable driving device (65).
22. A device according to claim 21, characterised in that the driving device has an electromagnet (65).
23. A device according to one or more of claims 20 to 22, characterised in that the covering plate (64) has a resilient or resiliently mounted sealing plate (641) on its side facing the yarn take-off tube (12).
24. A device according to claim 23, characterised in that the sealing plate (641) is constructed as a rigid sealing plate resiliently carried by the covering plate (64).
25. A device according to claims 19 and 23 or 24, characterised in that the covering plate (64) projects beyond the sealing plate (641) in the direction of feeder (5).
26. A device according to one or more of claims 18 to 25, characterised in that the take-off tube covering and the feeder (5) are pivotally mounted on a common pivot pin (52, 54).
27. A device according to one or more of claims 1 to 25, with a maintenance device capable of travelling along a plurality of adjacently arranged open end spinning devices, characterised in that the feeder (5), the two stops (7, 72; 7, 74) allocated to it as well as the yarn length adjusting device (9, 73, 75) are arranged on the maintenance device (15).
28. A method of piecing a yarn at an open-end spinning device, using a device according to one or more of claims 1 to 27, wherein the yarn is brought to a predetermined length by cutting and the yarn end by means of a feeder is moved beyond the take-off tube into a yarn introduction position out of which the yarn end is returned to the fibre collecting face of the open-end spinning device for piecing, characterised in that the cutting position and the yarn introduction position of the feeder are fixed at a predetermined value of the fibre collecting face of the open end spinning element and different yarn lengths for piecing are produced by return delivery or take-off of the yarn.
29. A method according to claim 28, characterised in that the cutting position and the yarn introduction position of the feeder are fixed at the smallest usable value of the fibre collection face of the open end spinning element and the additionally required yarn length is made available by a return delivery if larger sizes of fibre collecting face are used.

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