EP0258248B1 - Process and device for piecing threads on an open-end friction spinning device - Google Patents

Abstract

In order to join the threads on an open-end friction spinning device with two friction spinning elements (101) driven in the same direction and forming a suction-type tapered gap, the thread (30) is fed to the gap in such a way that the thread (30) first reaches the thread-forming region (104) with its free end. The feeding of the fibres into the tapered gap is controlled in such a way that the end of the thread (300) comes in contact with the fibres simultaneously with arrival in the thread-forming region (104). The friction spinning elements (101) are covered with a shroud (130) which forms a fibre-feeding duct (24). The shroud has, in addition to the fibre-feeding duct (24), a thread insertion slit (14) which extends essentially in the longitudinal direction of the friction spinning element (101). This extends from the outer side of the shroud (130) to its inner side and from the end of the withdrawal side up to a maximum distance of the end of the opening (240) which faces away from the withdrawal side. Outside the tapered gap a thread-holding device (7) is installed, which maintains the thread (3) essentially parallel to the thread input slit (14). This keeps the thread (30), at the withdrawal end of the friction element (101), away from the tapered opening until the end of the thread (30) has reached the tapered gap.

Description

The present invention relates to a method for piecing an open-end friction spinning device which has two friction spinning elements which are driven in the same direction and form a suction wedge gap, in which a thread end is delivered to a piecing position provided outside the wedge gap and is transferred out of this into a thread formation zone in the wedge gap where it is drawn off again as a continuous thread with the inclusion of the fibers fed to the wedge gap, and a device for carrying out this method.

In a known method of this type, the thread end is returned with the aid of a guide device with the cover open outside the wedge gap to a suction nozzle (DE-OS 3.318.266). By means of a suitable movement or a corresponding drive of the guide device, an intermediate section of the thread is transferred into the wedge gap of the friction spinning elements which have previously been shut down. The cover is then closed and the thread take-off is switched on. The friction spinning elements are then driven again and the fiber feed is switched on in such a way that the fibers reach the wedge gap at the same time as the thread end. Since the desired delivery quantity does not suddenly get into the wedge gap, but only gradually, a thin spot cannot be avoided after the thread end connected to the fibers. Such a thin spot leads to increased thread breakage numbers due to the lower strength. However, if the fiber feed starts before the thread end has been pulled out of the suction nozzle and into the wedge gap, a long, thick-pieced piecing is created which is not desired for optical reasons.

It is therefore an object of the invention to provide a method and a device for reliably spinning on an open-end friction spinning device and thereby keeping the defect in the spun thread that is created by the spinning small.

This object is achieved according to the invention in that the thread is fed to the wedge gap in such a way that the thread first reaches the thread formation zone with its free thread end, and the feed of the fibers into the wedge gap is controlled in such a way that the thread end simultaneously with reaching the thread formation zone comes into contact with the fibers. The area of the thread that comes into contact with the fibers is therefore quite short.

This thread area is now drawn off from the wedge gap and thereby binds in the fibers fed into the wedge gap. Since the thread end only comes into contact with the fibers when the thread formation zone is reached and is already in the wedge gap at the start of the spinning process and does not have to be inserted into this after another thread area has already started to bind fibers, the fault is in newly spun thread very short and usually even falls short of the length of the fiber feed zone, which is determined by the length of the mouth of the fiber feed channel. The thick point in the piecing is even shorter since not the entire length of the thread returned to the length of the friction spinning elements reaches the wedge gap, but only the end section of the thread facing away from the take-off side. A thin spot following the piecing can be avoided by timing the insertion of the fiber feed, which can be controlled independently of the thread feed into the wedge gap.

The method according to the invention, according to which the thread first reaches the thread formation zone with its free end, is also intended to include a method in the sense of the present invention in which only the end portion of the returned thread reaches the thread formation zone and the thread region between this end portion and the take-off side End of the wedge gap does not get into the thread formation zone at all. In this case, after the attachment has taken place, the previous thread end, which now forms this intermediate region of the thread, comes into this region of the wedge gap on the pull-off side during the pull-off movement of the thread. H. likewise only later, when the thread end has been fed to the thread formation zone for piecing.

In order to avoid thin spots in the piecing, it is advantageously provided according to the invention that the supply of fibers starts in the wedge gap before the thread end has reached the thread formation zone. The thread end is thus placed on the fiber mass collected in the wedge gap, which is now integrated into the thread end together with newly added fibers. In this way, the amount of fibers to be integrated in the piecer can be determined in a simple manner.

It has been shown that, after the fiber supply to the wedge gap has been interrupted, fibers which are still combed out from the fiber beard reaching into the combing area of the opening device or which are still in the clothing of the opening roller, enter the wedge gap. However, these fibers are no longer subject to any deduction and can thus damage the friction spinning elements. For this reason, the method according to the invention is such that when a thread break occurs, not only is the fiber supply to the friction spinning elements interrupted, but at the same time the friction spinning elements are stopped, and that during the return of the thread to the piecing position outside the wedge gap, the friction spinning elements are driven again, whereupon the supply of fibers in the wedge gap is released.

In order to have defined ratios during piecing, according to a preferred embodiment of the method according to the invention, when the friction spinning elements have stopped, fibers are briefly fed to the suctioned wedge gap, where then the wedge gap is removed and the fibers are sucked out of the wedge gap; the friction spinning elements are then driven again, and the supply of fibers into the wedge gap is released again in a manner coordinated with the previous interruption of the fiber supply.

In order that a longer period of time is available during piecing, it is expediently provided in a further embodiment of the method according to the invention that the friction spinning elements are driven at a reduced rotational speed during the feeding of the thread end into the thread formation zone until after the thread take-off has been inserted.

It is possible in various ways to feed the thread to the wedge gap in such a way that the thread reaches the thread formation zone first or even with its free end. This happens in a simple manner in that the thread is drawn off from the thread formation zone in such a way that it is deflected in the direction of the fiber feed side.

According to a further advantageous embodiment of the method according to the invention, the thread is fed radially to the wedge gap in such a way that the thread is placed outside the wedge gap on the friction spinning element which rotates into the wedge gap and is fed to the wedge gap by this friction spinning element. Such a process is air-saving. In this case, the procedure is preferably such that the thread end is placed obliquely on the friction element which rotates into the wedge gap in such a way that the free thread end is at a smaller distance from the wedge gap than the thread section located at the end of this friction spinning element on the take-off side.

According to a preferred method, the piecing position is selected such that the thread brought into the piecing position and transferred into the thread-forming zone, before being subjected to a draw-off, only extends into the area of the thread-forming zone to which the fibers are fed. Since the thread end does not extend beyond the area to which the fibers are fed at the moment it reaches the thread formation zone, the fiber feed can also start before the thread to be spun enters the thread formation zone. This possibility of starter has the advantage that a relatively long period of time is available for the insertion of the fiber feed.

Appropriately, the procedure is such that the thread is brought to a defined length, is returned a defined distance outside the wedge gap into the length range of the thread formation zone and the thread end is held in this position by clamping, so that fibers are then fed to the wedge gap and then the thread is placed on the fibers in the wedge gap. In this way, the piecing process can be precisely controlled in a simple manner.

Since, in the case of finer threads, fewer fibers are available for spinning due to the ratio between fiber delivery speed and thread take-off speed required for this, and there is therefore a risk of increased thread breakage during attachment, according to a further embodiment of the method according to the invention it is provided that the thread end is clamped in fine threads greater distance from the take-off end of the wedge gap than with coarse threads. This means that finer threads are in the wedge gap longer than coarse threads, which means that the differences in the speed relationships between fiber feed and thread take-off are somewhat compensated for during the preparation. The piecing security is increased.

The attachment can take place in such a way that the free thread end reaches the wedge gap while the thread is still held by the clamp. In this way it is ensured that the thread end always reaches the wedge gap earlier than the thread region facing the withdrawal end of the wedge gap. However, it has proven to be particularly advantageous if the thread is released from the fibers in the wedge gap when the thread end is placed on it. With the compact design of the friction spinning device, this enables precise control.

In an alternative embodiment of the method according to the invention, exact insertion of the thread take-off is achieved by first feeding the thread to the wedge gap by means of a clamping point movable in the thread take-off direction and then, without the thread being released by this clamping point, being pulled off the wedge gap by this movable clamping point becomes.

The thread drawn off from the wedge gap is expediently passed through the movable clamp to a storage location, which compensates for fluctuations in take-off when the take-off is taken over by the take-off device which carries out the normal spinning take-off. In the same way, such a storage location can also be used to temporarily store the excess thread lengths when the thread is transferred from the movable clamping point to the bobbin.

In connection with a bobbin change, according to the invention, the thread to be brought into the piecing position is first fed to the wedge gap and then to the storage location by the clamping point movable in the draw-off direction, from where the thread is transferred to a newly inserted empty tube.

The thread is fed from the nip into the wedge gap by the suction air acting on the friction spinning elements. According to the invention, this thread feed to the wedge gap can be supported by a compressed air flow directed into the wedge gap.

According to a further advantageous embodiment of the method according to the invention the threading is carried out by bringing the thread to a defined length, by a defined distance outside the wedge gap beyond the end of the thread formation zone facing away from the take-off side, back into the effective range of an elastic retention force, so that fibers are then fed to the wedge gap and the thread subtracted against the elastic retention force and after leaving the effective range of the elastic retention force is placed on the fibers located in the wedge gap.

To increase the piecing security when piecing fine threads, it is advantageously provided that the thread is placed later on the fibers located in the wedge gap with fine threads than with coarse threads. In this way, fibers can be pre-fed over a relatively long period of time, so that enough fibers are available for piecing in spite of the small fiber delivery quantity per unit of time. According to the invention, this can be further supported by the fact that the thread is subjected to a drawdown only after a delay after reaching the thread formation zone.

To carry out the method, the open-end friction spinning device has a cover for the friction spinning elements, which has a fiber feed channel and, in addition to the fiber feed channel, a thread insertion slot which extends essentially in the longitudinal direction of the friction spinning elements and which extends from the outside of the cover to its inside and from the end on the trigger side to a maximum extends to the mouth end of the fiber feed channel facing away from the take-off side, a thread holding device holding the thread essentially parallel to the thread insertion slot being arranged outside the wedge gap and a thread guide is also provided which keeps the thread at the take-off end of the friction spinning elements away from the wedge gap as long as the thread end keeps the wedge gap has not reached. The thread insertion slot enables the thread to remain outside the thread formation zone during its return to the piecing position and, when the cover is closed, can be fed out of this piecing position to the thread formation zone. For safe insertion of the thread into this thread insertion slot, the thread is held parallel to the thread insertion slot by the thread holding device. This thread holding device is arranged and controlled in such a way that, together with a thread guide, it releases the thread in such a way that it reaches the thread formation zone first or only with its free end, while the thread section between the thread end and the takeoff-side end of the wedge gap decelerates or does not get into the thread formation zone at all.

The thread guide can be designed differently and may also be formed by the thread holding device itself. According to a simple embodiment of the subject matter of the invention, the thread guide is designed as a deflection, which deflects the thread leaving the friction spinning elements in the direction of the cover.

The thread insertion slot can also be designed differently. Depending on the design of the thread holding device, it may be advantageous if the thread insertion slot, following its area that extends from the outside of the cover to the inside thereof, has an area adjoining it on the side facing away from the take-off side, which area has a slot bottom from the side The inside of the cover is separated, this slot bottom expediently forming an acute angle with the inner wall of the cover. This is particularly expedient if the thread holding device is designed as a suction air nozzle which opens into the end of the thread insertion slot facing away from the take-off side. This suction air nozzle initially picks up the returned thread and gradually releases it again after the thread draw has been inserted, the thread being prevented by a thread guide from entering the thread formation zone. This is only possible at the end of the thread after release by the suction air nozzle.

To achieve a space-saving design of the subject matter of the invention, it is advantageous if the suction air nozzle is arranged in the slot bottom. The suction air nozzle expediently opens into the slot bottom parallel to the thread formation zone.

However, the present invention is not tied to a specific design of the thread holding device. According to a preferred embodiment, this is designed as a thread clamp. This thread clamp is advantageously assigned a separating device which gives the thread a defined length and shape.

Such an embodiment of the subject matter of the invention is particularly advantageous in which the thread clamp can be moved from a thread take-up position for receiving a thread drawn off a bobbin into a thread transfer position for transferring the thread into the thread insertion slot. To control the piecing process, the movable thread clamp can carry a switch which is connected to a control device for controlling the piecing process and can be actuated from the cover when the thread transfer position is reached.

The thread clamp can preferably be moved along the thread insertion slot, the thread clamp for transferring the thread to the thread insertion slot in the direction of the thread take-off as far as the mouth of a pneumatic store arranged between the friction spinning elements and a winding device, and being controllable in such a way that the thread clamp only reaches the thread releases the pneumatic memory. In this way, defined piecing ratios are achieved in a simple manner, since both the thread feed into the thread bil tion zone as well as the withdrawal of the spun thread from this thread formation zone by one and the same element, namely the thread clamp.

When starting a new bobbin, it can be advantageous if an auxiliary thread is available for spinning. For this reason it can be provided according to the invention that an auxiliary spool is arranged on a maintenance carriage which can be moved along a plurality of open-end friction spinning devices, from which the thread can be fed to the thread clamp. For this purpose, the thread clamp itself can fetch the thread length required for piecing; however, a separate feed device can also be provided for this purpose, and depending on the design of the device, the thread extending to the auxiliary bobbin can also be severed between the auxiliary bobbin and the thread clamp during each piecing process.

To support the insertion of the thread into the thread insertion slot, a compressed air nozzle directed into the thread insertion slot, which blows the thread into the thread insertion slot, can be assigned to both a stationary and a movable thread clamp.

According to a preferred embodiment of the subject matter of the invention, the fiber feed channel opens into the wedge gap, while the thread insertion slot opens outside the wedge gap opposite the circumferential surface of the friction spinning element turning into the wedge gap. It is expediently provided that the end of the thread insertion slot on the take-off side is at a greater distance from the thread-forming zone than the end of the thread-forming zone facing away from the take-off side. This design of the subject matter of the invention ensures in a simple manner that when the thread is fed into the thread formation zone, the free thread end reaches the thread formation zone earlier than the intermediate thread section between the thread end and the take-off end of the wedge gap. It has proven to be advantageous if the angular distance between the end of the draw-off end of the mouth of the thread insertion slot opening on the inside of the cover and the thread formation zone is greater than 90 °.

In order to ensure that the thread is fed to the wedge gap as uniformly as possible, it is expediently provided that the thread insertion slot includes an angle of inclination of less than 90 ° with the direction of rotation of the friction spinning element screwing into the wedge gap.

A rapid insertion of the thread into the thread insertion slot is achieved according to the invention in that the thread insertion slot widens towards the outside of the cover. In this way, a reliable function is achieved even with larger movement tolerances.

In order to keep the air consumption during spinning low, it is advantageously provided that the thread insertion slot can be covered by a controllable closure member. The thread insertion slot is only released for piecing, while it is then covered again for normal spinning. It is expediently provided that this closure member can be controlled in connection with the other operations of the piecing process from a maintenance carriage which can be moved along a plurality of open-end friction spinning devices.

As mentioned above, it is advantageous if the thread take-off can be adapted to the respective spinning conditions by the thread take-off being decelerated and / or being driven at a reduced speed. In order to additionally prevent damage to the friction spinning elements, according to a further feature of the invention, the thread spinning elements are assigned a thread monitor controlling their drive and an auxiliary drive device which can be controlled by a maintenance carriage which can be moved along a plurality of open-end friction spinning devices.

Although the thread is fed to the wedge gap transversely to its longitudinal direction, the friction spinning elements according to the present invention remain covered during the entire piecing process. This enables a very individual and variable control of the piecing process, which can be optimally adapted to the respective spinning parameters (material, thread thickness, etc.). This enables safe and short piecing to be generated both in connection with thread breakage elimination and in connection with a bobbin change. Despite this optimized control, the device according to the invention is simple and space-saving in construction.

• Figur 1 in schematischer Seitenansicht eine erfindungsgemäss ausgebildete Spinnstelle mit einer Offenend-Friktionsspinnvorrichtung und einer bewegbaren Fadenklemme;
• Figur 2 in schematischer Seitenansicht eine erfindungsgemässe Friktionsspinnvorrichtung sowohl mit einer als Saugluftdüse als auch mit einer als Fadenklemme ausgebildeten Fadenhaltevorrichtung;
• Figur 3 in perspektivischer Ansicht die in Figur 2 gezeigte Friktionsspinnvorrichtung;
• Figur 4 eine Vorderansicht der in Figur 3 gezeigten Vorrichtung; und
• Figur 5 in der Seitenansicht eine Abwandlung der in Figur 2 gezeigten Vorrichtung mit lediglich einer als Fadenklemme ausgebildeten Fadenhaltevorrichtung.
• Fig. 1 zeigt eine Offenend-Friktionsspinnvorrichtung 10, der das Fasermaterial 3 mittels einer Zufuhr- und Auflöseeinrichtung 2 zugeführt wird. Zum Abziehen des gesponnenen Fadens 30 ist eine Abzugsvorrichtung 4 vorgesehen. Das abgezogene Garn wird mittels einer Spulvorrichtung 40 auf eine Spule 400 gewickelt, die durch eine Spulwalze antreibbar ist.

Several exemplary embodiments of the subject matter of the invention are explained in more detail below with reference to drawings. Show it:

• FIG. 1 shows a schematic side view of a spinning station designed according to the invention with an open-end friction spinning device and a movable thread clamp;
• FIG. 2 shows a schematic side view of a friction spinning device according to the invention with both a suction air nozzle and a thread holding device designed as a thread clamp;
• Figure 3 is a perspective view of the friction spinning device shown in Figure 2;
• Figure 4 is a front view of the device shown in Figure 3; and
• 5 shows a side view of a modification of the device shown in FIG. 2 with only one thread holding device designed as a thread clamp.
• 1 shows an open-end friction spinning device 10, to which the fiber material 3 is fed by means of a feed and dissolving device 2. A take-off device 4 is provided for pulling off the spun thread 30. The drawn-off yarn is wound by means of a winding device 40 onto a bobbin 400 which can be driven by a winding roller.

The open end friction spinning device 10 is together with the feed and dissolving device device 2 is provided stationary at the spinning station 1, of which a plurality are usually arranged side by side in a machine. A maintenance carriage 5 with a piecing device 50 can be moved along these spinning positions 1.

The open-end friction spinning device 10 has a housing 13 with two rotationally symmetrical friction spinning elements 100 and 101 (FIG. 3), which form a wedge gap 102. At least one of the friction spinning elements, e.g. B. the friction spinning element 101 is perforated and sucked during spinning in the area of the wedge gap 102. For this purpose, it is connected to a suction air line 11 via a valve 110 (FIG. 1).

The two friction spinning elements 100 and 101, which are formed in the exemplary embodiment of the rollers shown, are driven in the same direction (see arrows P7 in FIG. 3). For this purpose, each friction spinning element 100 and 101 has a whorl 103, against which a drive belt 120 rests. The drive belt 120 is wrapped around two rollers 121 - only one of which is visible in FIG. 1 - in such a way that it is always in a non-positive connection with the whorls 103 of the two friction spinning elements 100 and 101. On the outside of the drive belt 120 there is a drive roller 122 which receives its drive from a tangential belt 12 which extends over a large number of spinning stations 1 located next to one another. The drive roller 122 is carried by the armature 600 of a lifting magnet 60, which can be controlled from a control unit 6, and is thus adjustable in the directions of the arrow 8.

An auxiliary drive device 54, which is arranged on the maintenance carriage 5, can be delivered to the friction spinning elements 100 and 101. The auxiliary drive device 54 has a controllable drive roller 540 which is driven by a motor 542 via a (indicated) gear 541. The drive roller 540 is seated at the end of a rod 543 which can be displaced in the longitudinal direction (arrow P1).

So that the rod 543 can be freely moved during this longitudinal movement, the rod can also be pivoted in the vertical direction about a horizontal axis 544 (arrow P2). The axis 544 is mounted on a bearing block 55, which in turn can be rotated about a vertical axis 51 (arrow P3) in order to be able to bring the auxiliary drive device 54 back from the area of the spinning station 1 into the area of the maintenance carriage 5.

The feed and dissolving device 2 arranged upstream of the open-end friction spinning device 10 has a feed hopper 20, by means of which the band-shaped fiber material 3 is fed to a feed roller 21, with which a pressure roller or feed trough (not shown) cooperates in the usual way. The fiber material 3 is fed from the feed roller 21 to a dissolving roller 22 which dissolves the band-shaped fiber material into individual fibers. The opening roller 22 is driven in a known manner by a belt 23. A fiber feed channel 24 extends from the opening roller 22 into the wedge gap 102 of the friction spinning elements 100, 101.

The thread 30 drawn off by the open-end friction spinning device 10 by means of the draw-off device 4 is monitored on its way to the bobbin 400 driven by a winding roller 401 by a thread monitor 61, which is in control connection with the control unit 6.

The piecing device 50 arranged on the maintenance carriage 5 has a suction tube 500 (arrow P4) which can be pivoted against the bobbin 400 and by means of which a thread end can be sucked in from the bobbin 400. The bobbin 400 can be driven in a known manner from the maintenance carriage 5 in the unwinding direction, so that the thread end that is sucked in continues to get into the suction pipe 500. The suction tube 500 has a longitudinal slot (not shown) on its side facing the spinning station 1, so that the thread section sucked in between the slot end facing away from the spool 400 in the vicinity of the pivot axis 501 of the suction tube 500 and the spool 400 can take an elongated course. In this case, the thread 30 comes into the swivel range of a controllable thread clamp 70. The thread clamp 70 is part of a thread holding device 7 and is arranged on the free end of an arm 700 which is mounted on the maintenance carriage 5 in such a way that it makes a first pivoting movement about the pivot axis 51 in a horizontal plane (arrow P3) and about a pivot axis 701 can perform a second pivoting movement in a vertical plane (arrow P5). Arm 700 also carries a controllable compressed air nozzle 702.

The thread clamp 70 is assigned a pivotable suction tube 52 which is pivotably mounted on a horizontal axis 520, so that it can be pivoted from a receiving position in the vicinity of the thread clamp 70 into a transition position in the vicinity of the bobbin 400 in a vertical pivot plane (arrow P6). The suction pipe 52 is connected via a suction line 521 to a vacuum source (not shown).

FIG. 4 shows the housing 13 in a top view, while FIG. 5 shows the housing 13 in a side view. It can be seen from this that the housing 13 has a thread insertion slot 14 in its cover 130 facing the thread clamp 70. This thread insertion slot 14 extends from the outer side 131 of the cover 130 to the inner side 132 and runs next to the fiber feed channel 24 from the take-off end 133 of the housing 13 to the mouth end 240 of the fiber feed channel 24 facing away from the take-off side (FIG. 3). Since the thread insertion slot 14 is arranged next to the fiber feed channel 24, it opens next to the fiber feed channel 24 and thus outside of the wedge gap 1 02 opposite the friction spinning element 101 in the interior of the housing 13.

The device described above in construction works as follows:

The maintenance carriage 5 travels to the relevant spinning station 1 for piecing of a signal that the thread monitor 61 triggers when a thread break occurs, or when spinning after a machine standstill, in which the maintenance carriage 5 spins spinning station 1 onto spinning station 1. At the spinning station 1, the suction tube 500 is pivoted about its pivot axis 501 against the spool 400 that was already lifted off the winding roller 401 at an earlier point in time. While the bobbin 400 is driven from the maintenance carriage 5 by means of an auxiliary drive roller (not shown) in the unwinding direction, the suction pipe 500 takes up the unwound thread 30. If a sufficient length of thread has been sucked into the suction tube 500, the bobbin 400 is stopped and the suction tube 500 is pivoted away from the bobbin 400. The thread 30 emerges from the aforementioned longitudinal slot of the suction pipe 500. It assumes an extended position between the end of the longitudinal slot facing the pivot axis 501 and the coil 400. The thread 30 is thus in the pivoting range of the thread clamp 70. The horizontally and vertically pivotable thread clamp 70 is brought into the thread run into a thread take-up position, where it picks up the thread 30. It feeds the thread 30 to a separating device 53 (FIG. 1) provided in the maintenance carriage 5, which cuts the thread 30 on the side of the thread clamp 70 facing away from the bobbin 400. A certain thread length is created from the thread clamp 70 to the end of the thread 30, which is necessary for piecing. The thread clamp 70 is then pivoted in a combined horizontal and vertical movement to the open-end friction spinning device 10. The thread clamp 70 is in a thread transfer position in front of the thread insertion slot 14 (FIG. 5); the thread clamp 70 thus forms a thread holding device 7, which presents the thread end 300 to the thread insertion slot 14. The thread holding device 7 formed by the thread clamp 70 holds the thread 30 essentially parallel to the thread insertion slot 14.

During this return delivery of the thread 30 into its piecing position in front of the thread insertion slot 14, the friction spinning elements 100 and 101, which were previously stopped by lifting the drive roller 122 from the drive belt 120, are rotated again. For this purpose, the drive roller 540 is brought into contact with the drive belt 120 from the maintenance carriage 5. The friction spinning elements 100, 101 now receive their drive from the motor 542 via the drive roller 540 and the drive belt 120. This drive is completely independent of the machine's drive (tangential belt 12), so that the friction spinning elements 100, 101 are driven at a low speed which is particularly advantageous for piecing can be.

The previously switched off vacuum is now again applied to the friction spinning rollers 100, 101 with the help of the valve 110. Now the fiber feed is switched on again in a known manner. The sliver now arrives in the form of individual fibers in the wedge gap 102 and is twisted there into a fiber bundle 31 within a thread formation zone 104 (FIG. 5). However, this fiber bundle 31 does not get a real rotation since it can rotate freely in the wedge gap 102.

The compressed air in the compressed air nozzle 702 is released in time with the re-switching of the fiber feed into the wedge gap 102, so that the thread end 300 is blown into the thread insertion slot 14 (FIG. 5). This compressed air thus supports the suction air flow flowing through the suctioned friction spinning element 101. The thread end 300 thus reaches outside of the wedge gap 102 on the suctioned outer surface of the friction spinning element 101. Due to the negative pressure acting on the outer surface, the thread end 300 is carried along by the friction spinning element 101 rotating in the wedge gap 102 and placed on the rotating fiber bundle 31. The fiber bundle 31, which forms a still relatively loose fiber structure, is now screwed into the thread end 300.

It follows from the above that the thread end 300 does not come into contact with the fibers before the wedge gap 102 is reached, but that this contact is made simultaneously with the wedge gap 102 and thus the thread formation zone 104 being reached. In this way, a clean integration of the fibers into the thread end 300 is achieved. By controlling the speed of the friction spinning elements 100, 101 - d. H. Driving them at a reduced speed - during the piecing phase, a longer period of time can be provided until the thread take-off is inserted, which increases the piecing reliability.

As FIG. 5 clearly shows, only the end of the thread end 300 facing away from the take-off side reaches the wedge gap 102, while the take-off end of the thread end 300 is prevented by the thread clamp 70 from entering the wedge gap 102 through the thread insertion slot 14. Thus, the thread area coming into contact with the pre-fed fibers is only short and, as a rule, even shorter than the thread formation zone 104. This leads to short piecing and thus to short defects in the newly spun thread. The required strength of the piecer is achieved by relative control of fiber feed, thread feed, speed of the friction spinning elements 100, 101 and insertion of the thread take-off. In this way, a thin spot following the attachment point in the thread can also be avoided.

The thread 30 which is now forming again is pulled off from the thread formation zone 104 by continuing the movement of the arm 700 with the thread clamp 70, this depending on the piecing speed, fiber material etc. after interrupting the feed and feed movement of the thread holding device 7 or in a continuous manner this feed and feed movement can happen.

The thread holding device 7 forms at the same time a thread guide 75 for the thread 30 and, as mentioned, prevents the end of the thread end 300 on the take-off side from getting into the wedge gap 102. As the distance between this thread holding device 7, which forms a thread guide 75, increases, however, the newly forming thread 30 is given the opportunity to lie in the wedge gap 102 over the full length of the thread forming zone 104, although the thread 30 initially spins the thread forming zone only with its free end reached.

The spool 400 is also lowered back onto the spooling roller 401 in a time-coordinated manner with respect to the processes described. The bobbin 400 thus begins to rotate in the take-off direction and pull the thread 30 from the open-end friction spinning device 10. The thread clamp 70 is now opened. Voltage fluctuations that occur due to slipping of the coil 400 which is accelerating are absorbed by the suction air flow acting in the suction pipe 52. The suction pipe 52 stores the excess thread length until it is used up again by the tension delay when it winds up.

By inserting the thread take-off by means of the spool 400, the thread 30 gets into the clamping line of the take-off device 4 due to the increasing thread tension, possibly supported by suitable thread guide elements (not shown). Simultaneously with the lowering of the spool 400, this is also done via the lifting magnet 60 repositioning the drive roller 122 on the drive belt 120, while at the same time the drive roller 540 of the auxiliary drive device 54 releases the drive belt 120 again. The friction spinning elements 100 and 101 are thus driven again by the tangential belt 12 of the machine.

The device described with reference to FIG. 1 can also be used in connection with a coil change. The piecing can take place with the aid of auxiliary turns on the empty tube, so that the attachment takes place in the manner described. The piecing and the remaining rest of the auxiliary windings can also be temporarily sucked off with the help of the suction tube 52, whereupon the newly spun thread 30 is transferred with this suction tube 52 to the empty tube, which can be done in a manner known per se with the aid of a catch nose (not shown) etc the winding device 40 can be supported.

However, changing the bobbin is also possible without auxiliary turns on the empty tube. For this purpose, as shown in FIG. 1, an auxiliary spool 32 is seated on the maintenance carriage 5, from which the piecing thread 320 can be pulled off by the thread clamp 70. The piecing thread 320 is guided by the auxiliary bobbin 32 via a thread guide 321 and a thread clamp 322 to the area where the piecing thread 320 can be gripped by the thread clamp 70. The piecing thread 320 is guided by the thread clamp 70 through the separating device 53, where the piecing thread 320 receives the exact piecing length.

The piecing takes place as described. The thread clamp 70 is moved during the piecing draw-off in the direction of the winding device 40 up to the area of the mouth 522 of the suction tube 52. The thread clamp 70 is now controlled in such a way that it releases the thread 30, which is now sucked into the suction tube 52.

Now the suction tube 52 is pivoted to the winding device 40, where the thread 30 is transferred to the empty tube. When the thread 30 is picked up by the winding device 40, a certain length of thread is pulled out of the suction tube 52. In the vicinity of the mouth 522 of the suction tube 52 there is a cutting device 523 which, after the thread 30 has been transferred to the empty tube, cuts off the thread end extending into the suction tube 52. In this way, when changing the bobbin, the thread 30, which was previously fed to the suction tube 52 forming a storage location by the thread clamp movable in the draw-off direction, was transferred to a newly inserted empty tube in the winding device 40.

It was described above that the supply of fibers starts in the wedge gap before the thread end 300 has reached the thread formation zone 104, but it is also possible, depending on the piecing speed, fiber material etc., to control the fiber guidance in such a way that the fibers coincide with the thread end 300 reach the wedge gap 102. The thread end 300 is therefore always under the influence of fibers laying on the thread end 300 during the entire time it is in the wedge gap 102 and is thus prevented from jumping together by the increasing rotation in the thread 30.

In order to obtain secure piecing, an alternative embodiment of the piecing process described ensures that the outer surfaces of the friction spinning elements 100 and 101 are freed of residual fibers. For this purpose, fibers are briefly fed to the stopped but suctioned friction spinning elements 100 and 101, even before the thread end 300 reaches the thread insertion slot 14. The fiber feed and the suction of the friction spinning elements 100 and 101 are then set. The fibers are then sucked out of the wedge gap 102. This can be done, for example, by folding the cover 103 away from the rest of the housing 13 with the friction spinning elements 100 and 101 and instead bringing a controllable suction bell (not shown) in front of the friction spinning elements 100, 101 from the maintenance carriage 5. Alternatively, it can also be provided that the two friction spinning elements 100, 101 are spread in a manner known per se, so that the fibers can be sucked off by means of a suction device, not shown, which is arranged on the side of the friction spinning elements 100 and 101 facing away from the fiber feed channel 24. The temporary fiber feed results in an increase in the remaining fiber mass in the wedge gap 102, so that suctioning off the fibers is facilitated. This cleaning of the friction spin elements 100 and 101 has the effect that the same piecing conditions are always achieved in the wedge gap regardless of the thread breakage-related residual fibers. The piecing fiber is then fed in a manner that is timed to the previous interruption of the fiber feed, so that the fiber beard for piecing is always in the same state. The insertion of the thread end 300 into the thread insertion slot 14 should therefore be selected in accordance with the time for the piecing fiber feed.

If a thread break occurs, it is inevitable that a more or less large amount of remaining fiber remains in the wedge gap 102 of the friction spinning elements 100, 101. If the friction spinning elements 100, 101 rotate without this fiber mass being subjected to a deduction, it can happen that this fiber mass attaches to the friction spinning elements 100, 101 and runs through the clamping point of the friction spinning elements 100, 101 several times. Over time, this leads to damage to the friction spinning elements 100, 101. In order to prevent this danger, one can alternatively proceed in such a way that if a thread break occurs, not only is the fiber supply to the wedge gap 102 interrupted, but also the friction spinning elements 100, 101 be stopped immediately. On the basis of the thread break signal emitted by the thread monitor 61, the control unit 6, via the lifting magnet 60, causes the drive roller 122 driven by the tangential belt 12 to be separated from the drive belt 120, as a result of which the latter stops. The re-driving of the friction spinning elements 100 and 101 required during piecing then takes place from the maintenance carriage 5 via the auxiliary drive device 54. The fiber feeding is switched on and the thread end 300 is fed into the wedge gap in the manner described.

To make it easier to insert the thread end 300 into the thread insertion slot 14, the latter widens toward the outside 131 of the cover 130 in accordance with FIG. In order to be able to feed the thread end 300 to the thread formation zone in a calm state, the smallest angular distance β between the thread insertion slot 14 and the thread formation zone 104 is at least 90 °. According to FIG. 3, this angular distance β between the take-off end of the opening 143 of the thread insertion slot 14 opening on the inside 132 of the cover 130 from the thread formation zone 104 is even greater. Furthermore, the thread insertion slot 14 includes an angle of inclination y of less than 90 ° with the direction of rotation (arrow P10) of the friction spinning element 101 screwing into the wedge gap 102.

As mentioned, the end of the thread end 300 on the draw-off side is prevented by the thread clamp 70 from entering the thread-forming zone 104, at least not until the end of this thread section facing away from the draw-off side has reached the thread-forming zone 104. This effect can be supported or can be achieved solely by placing the thread end 300 obliquely on the friction spinning element 101 turning into the wedge gap 102 in such a way that the side facing away from the take-off side, i. H. free thread end has a smaller distance from the wedge gap 102 than the withdrawal-side end of this thread end 300 placed on the friction spinning element 101 at the same time. For this purpose, according to the embodiment shown in FIGS. 3 and 4, it is provided that the take-off end 140 of the thread insertion slot 14 is at a greater distance from the thread formation zone 104 than the end 141 of the thread insert slot 14 facing away from the take-off side.

The thread 30 can be presented in front of the thread insertion slot 14 by the thread clamp 70 in various ways. As shown in FIG. 1, the thread clamp 70 can be pivoted in both the horizontal and the vertical plane, so that the thread can also be fed to the thread insertion slot 14 from the side. In order to be able to use the thread clamp 70 as a take-off element for the duration of the piecing process, however, the thread clamp 70 in the area of the thread insertion slot 14 is usefully parallel-d. H. in the thread take-off direction - to this thread insertion slot 14, since the thread is fed in this way by one and the same pivoting movement, possibly with a short interruption in the area of the thread insertion slot 14, the thread insertion slot 14 and thus the wedge gap 102 and then removed again from the wedge gap 102 can.

In order to ensure that the thread end 300 reaches the thread formation zone 104 exactly in the desired length, the piecing position is selected in a very specific manner. First, the thread 30 is brought to a defined length by the separating device 53 and is brought outside the wedge gap 102 into the length region of the thread formation zone 104, where it is still held by the thread clamp 70. This piecing position is determined such that after switching on the fiber feed, the thread end 300 now sucked into the thread insertion slot 14 by applying the negative pressure to the suctioned friction spinning element 101 reaches the wedge gap 102 within the length range of the thread formation zone 104, but does not extend beyond it at any of its ends. As a result, the thread 30 is placed in a precisely defined length on the fibers located in the wedge gap 102 and forming a rotating fiber bundle 31.

It follows from the above that, in principle, the compressed air nozzle 702 can be dispensed with, since the thread 30 is sucked in solely by the action of the negative pressure applied to the friction spinning element 101. The compressed air nozzle 702 thus only acts as a support and enables the thread end 300 to be supplied to the wedge gap 102 more quickly and therefore more precisely in terms of time.

In the described embodiment, the thread clamp 70 is movable in the direction of the thread insertion slot 14. It has been shown that there are advantages for a safe piecing if the thread clamp 70 when the thread is inserted of the 300 in the thread insertion slot 14, ie when the thread end 300 is fed to the wedge gap 102, has different distances from the take-off end of the wedge gap 102 and thus the thread formation zone 104. For this reason, the thread clamp 70, ie its transfer position, is adjustable. The finer the thread, the greater the length of the thread end 300 located in the thread formation zone; conversely, the thread length located in the wedge gap 102 need not be so great for coarser yarns. This is due to the fact that the amount of fiber supplied per unit of time is smaller in the case of finer yarns than in the case of coarser yarns, so that the fiber mass required for sufficient strength of the piecer is only reached after a somewhat longer period of time.

As an alternative or in addition to the described measure, it can be provided to increase the piecing security that the thread end 300 is placed later on the fibers located in the wedge gap 102 with respect to the switching on of the fiber feed for fine threads than for coarse threads. In spite of the small fiber delivery quantity per unit of time in the case of fine threads, a sufficient fiber mass can accumulate in the wedge gap 102 in this way, so that reliable piecing is ensured. This timing is done by appropriately controlling the movement of the arm 700 and the air nozzle 702.

A further supporting measure is an adapted control of the withdrawal of the thread 30 from the thread formation zone 104. In order to give the thread end 300 sufficient time to connect to the fiber bundle 31 located in the wedge gap 102 by twisting, the thread 30, after it has passed the thread formation zone 104 has reached, only subject to a delay after a deduction. In the exemplary embodiment described, this is done by stopping the thread clamp 70 for inserting the thread end 300 into the thread insertion slot 14 and maintaining a certain downtime until the start of the pivoting movement of the thread clamp 70 causing the take-off. If the thread take-off is carried out after the thread 30 has been released by the bobbin 400, the time for lowering the bobbin 400 onto the winding roller 401 must be selected accordingly. In this case too, the delay until the thread pull-in is started is to be chosen larger for fine threads than for coarse threads.

Since the thread end 300 is held at least for a certain time by the thread clamp 70 even after it has been fed to the wedge gap 1 02, it is ensured that the thread 30 first enters the thread formation zone 104 only with its free end and only then with its region on the take-off side. However, the thread end 300 can also be fed into the wedge gap 1 02 by releasing the clamping action of the thread clamp 70, the piecing draw-off then taking place through the bobbin 400, which is again lowered onto the spinning roller 401. If, despite reinserting thread take-off (through the spool 400), this contacting of the thread-side thread area with the thread formation zone 104 is to be prevented even longer after the thread clamp 70 has released it, this can be done with the help of a thread guide 73 in front of the friction spinning elements 100, 101 Fig. 2 happen, which can be brought from the position shown to the dashed position 73 '. This thread guide can be formed, for example, by a bracket pivotable in the direction of arrow P9. As a result, the thread 30 drawn off from the thread formation zone 104 is moved in the direction of the fiber feed side, ie. H. to the side facing the fiber feed channel 24.

Another modification of the described device is described below with reference to FIGS. 2 to 4. As these figures clearly show, the thread insertion slot 14 is separated from the inside 132 of the cover 130 in its area facing away from the take-off side by a slot bottom 142. In the embodiment shown, this slotted base 142 forms an acute angle a with the inner wall of the cover 130.

In this embodiment, a suction air nozzle 71 serves as the thread holding device 7, which opens into the end 141 of the thread insertion slot 14 from the side facing away from the take-off side. For construction reasons (space saving), the suction air nozzle 71 opens into the slot bottom 142 parallel to the thread formation zone 104.

By a feed element, e.g. 1 in the manner of the thread clamp 70 shown in FIGS. 1 and 5, the thread 30 is brought from the bobbin 400 up to the thread insertion slot 14 and is exposed to the effect of the controllable suction air flow in the suction air nozzle 71. This suction air flow exerts an elastic restraining force on the thread 30 and, when released by the thread clamp 70, continues to pull it off until the thread 30 is stopped by stopping the bobbin 400 rotated back during the thread return. The movable thread clamp 70 now releases the thread 30 so that it is held solely by the suction air nozzle 71.

In order to prevent the thread, which extends from the spool 400 into the now ineffective suction air nozzle 71, from loops which can prevent proper functioning when spinning, with a longer machine standstill, according to FIG. 4, a fixed thread clamp 72 is additionally provided as per rigid clamping element provided. In the embodiment shown, this has a rigid clamping element 720, with which a movable clamping element 721 (arrow P11) cooperates. This movable clamping element 721 can be acted upon in one direction of movement by a lifting magnet 722 and acted upon in the opposite direction by a retaining spring 723.

To feed the thread end 300 to the wedge gap 102, the suction air in the suction air nozzle 71 is switched off and the thread 30 is released by the thread clamp 72, so that the thread end 300 due to the friction spinning element 101 acting vacuum is sucked into the thread insertion slot 14. The thread end 300 slides along the slot bottom 142. In order to prevent the thread end 300 from jumping from the slot bottom 142 and thus an uncontrolled movement of the thread end 300, this slot bottom 142 is inclined at an acute angle a to the wedge gap 102. In order to ensure in this embodiment that the free end of this thread end 300 comes into contact with the fibers in the wedge gap 102 in front of the region of the thread section facing the take-off side, the thread guide 73 shown in FIG. 2 is used for piecing from the position shown in FIG brought the position 73 '.

In this way, the thread 30 is deflected towards the fiber feed side during the piecing process.

In order to adapt to different thread sizes in the embodiment shown in FIG. 4, it can be provided that the thread clamp 72 can be adjusted in different positions parallel to the wedge gap 102 (arrows P12).

In order to obtain a defined thread length for piecing, there are various ways to proceed. It is thus possible to bring the thread 30 to a defined length with the aid of the separating device 53 mentioned. The thread 30 is then fed to the thread holding device 7 formed by the suction air nozzle 71 and is supplied outside the wedge gap 102 beyond the end of the thread formation zone 104 facing away from the take-off side and into the suction air nozzle 71 by a defined length. This can be done, for example, by releasing a previously formed thread reserve. Now fibers are fed to the wedge gap 102. The thread 30 is pulled in a timed manner against the elastic retention force exerted by the suction air nozzle 71 on the thread 30 until the thread 30 leaves the effective range of the elastic retention force of this suction air nozzle 71 and through the thread insertion slot 14 onto the wedge gap fibers located in the thread formation zone 104 is placed. By temporarily interrupting the thread take-off, the desired dwell time of the thread end 300 in the thread formation zone 104 can be determined.

In order to be able to keep the time tolerances for the return of the thread 30 into the suction air nozzle 71 relatively large, a separating device 710 is provided in the suction air nozzle 71 according to the embodiment shown, which gives the returned thread 30 a defined length. In addition, this separating device 710 causes the thread end, which has received an undefined length and shape as a result of the pneumatic return delivery and holding by unscrewing and sucking out individual fibers, again taking on a defined shape.

For exact control of the piecing process, according to FIG. 3, the cover 130 carries an initiator 80 for controlling a closure element 8, by means of which the thread insertion slot 14 is covered during the standstill of the spinning station 1 and during the normal spinning process. The closure member 8 extends parallel to the thread insertion slot 14 essentially over its entire length and is connected to the armature 810 of a lifting magnet 81, which in turn is in control connection with the initiator 80 via the control member 6.

The initiator 80 is arranged on the cover 130 in such a way that the closure member 8 immediately releases the thread insertion slot 14 when the arm 700 moved in the direction of the suction air nozzle 71 reaches the cover 130. Its arrangement at the trigger-side or opposite end of the cover 130 thus depends on the feed direction of the thread 30.

Furthermore, a switching flag 74 is provided on the cover, which triggers a pulse on the arm 700 in a switch (not shown) designed as an initiator when the thread clamp 700 has reached its transfer position. This second initiator causes the thread clamp 70 to open, so that the thread 30 can be sucked into the suction air nozzle 71. In addition, this second initiator can be connected to a control device for controlling the piecing process and can be used to trigger the piecing program.

In the embodiment described, in which each spinning station 1 is individually spun on, the closure member 8 can be controlled from the maintenance carriage 5 which can be moved along the machine. If, however, a device for mass piecing a plurality of open-end friction spinning devices 10 is provided, this closure member 8 can also be controlled centrally from a machine-side control device.

As can be seen from the above description, the subject matter of the invention can be modified in many ways and is therefore not limited to the exemplary embodiments shown. Further modifications are possible by exchanging features with one another or by replacing them with equivalents and combinations thereof and fall within the scope of the present invention. Thus, the invention is not restricted to the design of a thread return device designed as a thread clamp 70, since instead of this thread clamp 70 a pneumatic gripper can also be used.

In the described exemplary embodiments, the fiber feed channel 24 opens directly into the thread formation zone 104, while the thread insertion slot 14 opens towards the peripheral surface of the suctioned friction spinning element 101; with appropriate timing of fiber supply and thread return, it can also be provided that the fibers are fed onto the outer surface of the friction spinning element 101 and brought into the thread formation zone 104 by its rotation, while the thread insertion slot opens directly into the thread formation zone 104.

Claims (42)

1. A method for joining the thread in an open-end friction-spinning device comprising two friction-spinning elements driven in the same direction and forming a negative-pressure wedge- shaped nip, a thread portion being delivered to a thread-joining position dispoed outside the nip and transferred thence to a thread-forming zone in the nip, from which it is drawn off as a continuous thread, after splicing the fibres supplied to the nip, characterised in that the thread is supplied to the nip so that its free end first reaches the thread-forming zone and the supply of fibres to the nip is controlled sothatthethread portion comes in contact with the fibres at the same time as it reaches the thread-forming zone.

2. A method according to claim 1, characterised in that the supply of fibres into the nip starts before the thread portion has reached the thread-forming zone.

3. A method according to claim 1 or 2, characterised in that if the thread breaks the fibre supply to the friction-spinning elements is interrupted and the elements are stopped and restarted outside the nip while the thread is being returned to the joining position, after which the supply of fibres to the nip is allowed to continue.

4. A method according to claim 3, characterised in that when the friction-spinning elements are stopped, fibres are briefly supplied to the negative-pressure nip, after which the suction of the nip is stopped and the fibres are sucked from the nip, after which the friction-spinning elements are again driven and the supply of fibres to the nip is allowed to restart in time with the previous stoppage of the fibre supply.

5. A method according to one or more of claims 1 to 4, characterised in that the friction-spinning elements are driven at reduced speed during the supply of the thread portion to the thread-forming zone until drawing-off of the thread has started.

6. A method according to one or more of claims 1 to 5, characterised in that when the thread is drawn off from the thread-forming zone it is deflected in the direction towards the fibre supply end.

7. A method according to one or more of claims 1 to 6, characterised in that the thread is placed outside the nip on the friction-spinning element rotating into the nip and supplied thereby to the nip.

8. A method according to claim 7, characterised in that the thread portion is laid obliquely on the friction-spinning element rotating into the nip so that the free thread end is at a shorter distance from the nip than the thread portion at the drawing-off end of the friction-spinning element.

9. A method according to one or more of claims 1 to 8, characterised in that the thread-joining position is chosen so that the thread brought into the joining position and transferred to the thread-forming zone, extends, before being drawn off, only as far as the thread-forming zone to which the fibres are supplied.

10. A method according to one or more of claims 1 to 9, characterised in that the thread is brought to a specific length, delivered outside the nip to the length region of the thread-forming zone, the thread portion is held in this position by clamping, fibres are then supplied to the nip, and the thread is then laid on the fibres in the nip.

11. A method according to claim 10, characterised in that the clamping of the thread portion in the case of finer threads occurs at a greater distance from the drawing-off end of the nip than for coarse threads.

12. A method according to one or more of claims 9 to 11, characterised in that the thread clamping is release in order to lay the thread portion on the fibres in the nip.

13. A method according to one or more of claims 9 to 11, characterised in that a clamping station movable in the thread drawing-off direction supplies the thread to the nip and subsequently draws it away from the nip.

14. A method according to one or more of claims 10 to 13, characterised in that the supply of thread to the nip is assisted by a stream of compressed air.

15. A method according to claim 13 or 14, characterised in that the movable clamping station delivers the thread to a storage station.

16. A method according to claim 15, characterised in that the thread previously supplied to the storage station by the clamping station movable in the drawing-off direction is transferred to a newly- inserted empty former.

17. A method according to one or more of claims 1 to 8 or 10 to 16, characterised in that the thread is brought to a specific length, returned for a specific distance outside the nip and via the end of the thread-forming zone remote from the drawing-off end and into the range of operation of an elastic retaining force, fibres are then supplied to the nip and the thread is drawn off against the elastic retaining force and, after leaving the range of action of the retaining force, is laid on the fibres in the nip.

18. A method according to one or more of claims 1 to 17, characterised in that in the case of fine threads, the thread is laid on the fibres in the nip later than in the case of coarse threads.

19. A method according to one or more of claims 1 to 18, characterised in that the thread is delayed before being drawn off after reaching the thread-forming zone.

20. A device for working the method according to one or more of claims 1 to 19, comprising a cover covering the friction-spinning elements and holding a fibre supply duct, characterised in that the cover (130) in addition to the fibre supply duct (24) comprises a thread feeder slot (14) extending substantially in the longitudinal direction of the friction-spinning elements (100, 101 ) and reaching from the outside (131) of the cover (130) to the inside thereof (132) and from the drawing-off end up to, but not further than, the mouth end (240) of the fibre supply duct (24) remote from the drawing-off side, a thread-holding device (7) holds the thread (30) substantially parallel to the thread feeder slot (14) and a thread guide (70, 72, 73) is provided and holds the thread (30) away from the nip (102) at the drawing-off end of the friction-spinning elements (100, 101) until the thread portion has reached the nip (102).

21. A device according to claim 20, characterised in that the thread guide is constructed as a deflecting means (73) by means of which the thread (30) leaving the friction-spinning elements (100, 101) is deflected towards the cover (130).

22. A device according to claim 20 or 21, characterised in thatthe region of the thread feeder slot (14) remote from the drawing-off end is separated by a slotted plate (142) from the inside (132) of the cover (130).

23. A device according to claim 22, characterised in that the slotted plate (142) includes an acute angle (a) with the inner wall (132) of the cover (130).

24. A device according to one or more of claims 20 to 23, characterised in that the thread-holding device (7) is constructed as an suction-air nozzle (71 ) which opens into the end (141) of the thread feeder slot (14) remote from the drawing-off side.

25. A device according to claim 24, characterised in that the suction-air nozzle (71 ) is disposed in the slotted tray (142).

26. A device according to claim 25, characterised in that the suction-air nozzle (21 ) opens into the slotted tray (142) parallel to the thread-forming zone (104).

27. A device according to one or more of claims 20 to 26, characterised in that the thread-holding device (7) is constructed as a thread clamp (70, 72).

28. A device according to claim 27, characterised in that the thread clamp (70) is associated with a cutting device (53).

29. A device according to claim 27 or 28, characterised in that the clamp (70) is movable from a position for receiving a thread (30) drawn off a spool (400) into a position for transferring the thread (30) to the thread feeder slot (14).

30. A device according to claim 29, characterised in that the movable thread clamp (70) bears a switch connected to a control device for controlling the thread-joining process and adapted to be operated from the cover (130) when the thread transfer position is reached.

31. A device according to one or more of claims 27 to 30, characterised in that the thread clamp (70, 72) is adjustable along the thread feeder slot (14).

32. A device according to claim 31, characterised in that, in order to transfer the thread (30) at the slot (14) in the drawing-off direction to the mouth (522) of a pneumatic store (52) disposed between the friction-spinning elements (100, 101) and a spooling and winding device (40), the thread clamp (70) is movable and controllable so that it does not release the thread (30) until it is near the pneumatic store (52).

33. A device according to claim 32, characterised by an auxiliary spool (32) which is disposed on a maintenance truck (50) movable along a number of open-end friction-spinning devices (10), and from which the thread (30) is suppliable to the clamp (70).

34. A device according to one or more of claims 27 to 33, characterised in that the clamp (70, 72) is associated with a compressed-air nozzle (702) directed towards the thread feeder slot (14).

35. A device according to one or more of claims 20 to 34, characterised in that the fibre supply duct (24) opens into the nip (102) and the thread feeder slot (14) opens outside the nip (102) towards the peripheral surface of the friction spinning element (101) rotating into the nip (102).

36. A device according to claim 35, characterised in that the withdrawal end (141) of the thread feeder slot (14) is further from the thread-forming (104) than the end of the thread feeder slot (14) remote from the drawing-off side.

37. A device according to claim 35 or 36, characterised in that the angular distance ((3) between the thread-forming zone (104) and the drawing-off end of the mouth (143) of the slot (14) opening on to the inside (132) of the cover (130) is greater than 90°.

38. A device according to one or more of claims 35 to 37, characterised in that the thread feeder slot (14) includes an angle of inclination (y) of less than 90° with the direction of rotation (P10) of the friction-spinning element (101) rotating into the nip (102).

39. A device according to one or more of claims 20 to 38, characterised in that the thread feeder slot widens towards the outside (131) of the cover (130).

40. A device according to one or more of claims 20 to 39, characterised in that the thread feeder slot (14) is coverable by a controllable closure means (8).

41. A device according to claim 40, characterised in that the closure means (8) is controllable by a maintenance truck (5) movable along a number of open-end friction-spinning devices (10).

42. A device according to one or more of claims 22 to 41, characterised in that the friction-spinning elements (100, 101) are associated with a thread monitor (61 ) controlling their drive and an auxiliary drive means (54) controllable from a maintenance truck (5) movable along a number of open-end friction-spinning devices.

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