EP1375709B1 - Piecing method for, or piecing of, spinning stations in Air vortex spinning machines - Google Patents

Description

The invention is in the field of spinning technology and relates to a method according to the preamble of the first claim. The inventive method is used to prepare a yarn which is formed in a spinning machine or in a spinning unit of an air spinning machine from a staple fiber material, for example after a can change, after a bobbin change, after a yarn breakage or after another spinning failure. The method can also serve for piecing, that is, for the restart of a spinning process. The invention further relates to a spinning station equipped for carrying out the method according to the invention according to the preamble of the corresponding independent patent claim.

Air-jet spinning machines are in particular a device for producing a spun yarn from a fiber structure comprising a fiber guide channel with a fiber guide surface for guiding the fibers of the fiber assembly in an inlet mouth of Garnführungskanals, further comprising a fluid means for generating a vortex flow around the inlet mouth of Garnführungskanals and the inventive Measure for influencing the flow conditions in the spindle channel of a stationary spindle.

Air-jet spinning machines for spinning staple fiber materials usually have a large number of spinning stations, wherein a yarn is spun in each spinning station from a fed longitudinal fiber structure. The fiber longitudinal structure is first refined, that is, the amount of fiber per unit length is reduced by delay. Then the refined fiber strand is spun by twisting into a yarn, which yarn is then peeled off and wound up. For refinement, the fiber longitudinal structure is stretched, for example, by means of a drafting device or dissolved by means of an opening roller. For yarn formation by twisting an air-spinning method is used, that is, the yarn formation is done by air-twist distribution.

After an interruption of the air-spinning process, in which the connection between the spun yarn and the refined fiber structure (fiber longitudinal structure) to be spun is broken, this connection must be restored, not only so that the yarn produced is uninterrupted, but also so that the spinning process can be restarted. For such a reconnection of yarn and fiber longitudinal structures, the free yarn end resulting from the interruption, in particular in air-spinning processes, is pulled out and positioned upstream of the normal yarn conveying direction through the twist distribution point. Then, the yarn take-off and the air twist distribution are put back into operation and the free beginning of the refined fiber longitudinal formation is fed to the air twist distribution such that during a short transition time the end region of the yarn and the beginning region of the fiber structure move together through the twist distribution point. In this case, the fibers of the fiber structure are swirled by the twist distribution with the fibers of the yarn end region and the initial region of the fiber structure is bonded to the end region of the yarn in a kind of splice. The spinning process is thus put back into operation.

When piecing, that is to say at a restart of a spinning process, it is possible to proceed in the same way, whereby an auxiliary yarn is used instead of the end region of the yarn produced before the spinning interruption.

So that the Ansetzstelle allows a trouble-free continuation of the spinning process, this itself and its environment must have a sufficient tear strength for this purpose, that is usually that this tensile strength should be at least as large as the tensile strength of the yarn produced in the present spinning process.

There are various methods known to obtain a sufficient tensile strength of the Ansetzstelle. These methods will attack at the free end of the yarn, at the free beginning of the refined fiber strand and / or at the timing of the movement of the yarn end region and fiber strand starting region through the twist distribution.

It is for example from the publication DE-4240653-A1 It is known to roughen the end portion of the yarn, or to detach fiber ends from the dense fiber strand of the yarn and to spread them apart from the yarn, thereby improving the entanglement with the newly introduced fibers and increasing the tensile strength of the piecing point.

It is also known from the same publication to prepare the yarn end region for splicing in such a way that the fiber mass gradually decreases towards the yarn end, so that the yarn tapers towards its end. Such a tapering yarn end region is then passed through the twist distribution point for splicing with a correspondingly tapered beginning of a longitudinal fiber structure (gradually increasing fiber mass).

The use of a _" sharpened" initial region of a fiber dressing for setting is described, for example, in the publication US-5802831 (Murata ). According to this publication, a fiber longitudinal structure is warped before the twist distribution in a drafting system, wherein the drafting system has an inlet-side pre-draft zone and an outlet-side main draft zone. After an interruption of the spinning process, the inlet of the fiber longitudinal structure in the drafting system and the pre-delay is stopped. The fact that the main delay is not stopped, the fiber longitudinal structure between the pre-draft zone and the main draft zone is torn, where it forms a free beginning. After the interruption of the inlet and the pre-delay is synchronized with the twist distribution and the Garnabzug again coupled to the corresponding drive. The initial region of the longitudinal fiber structure, which is believed to have a tapered shape as a result of the tearing off, is first subjected to the main distortion, it being assumed that the said taper is stretched accordingly, thereby providing an improved attachment point.

The method according to US 5802831 will after the publications US 5809764 and US 5934058 (both Murata ), characterized in that the tapering initial region of the longitudinal fiber structure is shortened prior to stretching by tearing off a small piece, and in that in a draft that between drafting and Drallerteilungsstelle is used, the fiber mass of this initial area is additionally reduced specifically.

It turns out that it is difficult to create with the above methods Ansetzstellen that can meet the requirements. The used according to the methods mentioned yarns tend to have a weak point with a too small fiber mass immediately after a piecing. For this reason, usually the Ansetzstelle is given with a comparison with the rest of the yarn up to 200% increased fiber mass sure for piecing tensile strength.

This problem is also addressed by an earlier European application of the Applicant ( EP 01129189.5 ) at the number EP 1219 737 A1 which, however, is unpublished at the time of filing this application and the content of which is incorporated in this application as an integral part thereof. The subject matter of this earlier application is supplemented by the following invention.

In addition to the piecing quality (firmness of the piecing point), the piecing or piecing methods of the prior art still have a further disadvantage. In these methods, the piecing does not always succeed, so that the proportion of failed piecing on the total number of attempted piecing operations can be relatively high.

The object of the invention is now to provide a method for setting or piecing, which has a high probability of success of the piecing process and with the quality of Ansetzstellen, in particular the tensile strength is improved.

This object is achieved by the method according to the independent main claim.

The method according to the invention is based on the recognition that the chances of obtaining a successful piecing process are substantially higher if the overlapping ones are successful End portions of the yarn end and the torn fiber longitudinal structure are pressed together in the overlapping state. By compressing the fibers of the yarn end and longitudinal fiber structures (ie fiber strand), the intervening frictional forces (ie, static friction forces) are increased. This increased cohesion of the end regions has a positive effect on the subsequent course of the piecing process. In particular, the likelihood is reduced that the so-called _" soldered-together" end regions separate before the means for imparting twist or on average, for example during the impulse distribution by means of air, and the attaching process thereby fails. The process reliability of the piecing or piecing process and thus also the process reliability of the air spinning machine is thereby increased.

In addition, it has surprisingly been found that the piecing quality is increased with respect to tear strength. Thus, it is no longer necessary that the piecing or the Ansetzstelle for a sufficient tear strength has compared to the remaining yarn up to 200% increased fiber mass. The piecing thus has a much smaller thickness. Thanks to the tensile strength, the length of the placement can be chosen shorter. The fact that both the fiber mass and the length of the piecing is reduced, the disadvantages which are associated with a piecing, are reduced overall.

The compression of the overlapping end portions of the yarn end and the torn fiber longitudinal structure is preferably realized by the existing possibilities, i. without additional devices. Particularly suitable for this purpose is the clamping point of the downstream-driven part of the refinement unit (for example pair of outfeed rollers in the main drafting of the drafting system). In principle, according to the idea of the invention, it would also be possible for the piecing process to provide a special clamping-type pressing device which compresses the yarn end and the torn fiber longitudinal structure.

As favorable, but not absolutely necessary, the variant has been found to roughen or taper the yarn end or its end region to be overlapped, for example with a device according to DE4240653-A1 , Also, the use of a pointed end region of the longitudinal fiber structure, eg according to US 5802831 , is possible.

The inventive method and its device will now be explained with reference to an embodiment. The embodiment is based on the FIG. 1 explained. It should, however, be explicitly pointed out that the claimed invention is not limited to the exemplary embodiment shown.

FIG. 1 shows an exemplary embodiment of a spinning station of air-spinning machines for carrying out the inventive method. This spinning station is equipped for a so-called air spinning process with refinement by stretching. The spinning station has a means 3 for air twist distribution with a nozzle block 21 with nozzles 22 embedded therein, a spindle 23 with a yarn channel 24 and a feed block 25 with a fiber feed channel 26 and a needle 27 directed against the entrance of the yarn channel 24. For refinement, the spinning station as a refinement unit on a drafting system 28 with, for example, three pairs of cylinders (inlet cylinder 29, central cylinder 30 with straps 31 and outlet cylinder 32 with nip 11).

The inlet of the drafting device 28, so for example, the inlet cylinder 29 and the central cylinder 30 with straps 31 are driven by a motor 33. The motor 33 is controllable by a control unit 34. The control unit 34 uses for the control of the motor 33, a ready signal 35 and a yarn end signal 36 for determining the exact position of the end 2 of the yarn end 1 of a yarn end sensor 37, and spinning unit-own parameters.

During the known spinning process in the spinning station according to FIG. 1 the fiber longitudinal formation 10 'fed in the feed direction Z enters into the refinement between the inlet cylinders 29, and becomes entangled with a usually constant draw ratio between inlet cylinders 29 and center cylinders 30 and between a central cylinders 30 and outlet cylinders 32 subjected to an optionally variable draw ratio. The refined fiber elongate structure 10 is drawn from the discharge cylinders 32 through the fiber supply channel 26 against the entrance of the yarn channel 24. Compressed air supplied by the nozzles 22 generates, in addition to the aforementioned suction effect in the region of the yarn channel entrance, a swirling flow which serves for the swirl distribution. The yarn 11 produced by this twist distribution is drawn off through the yarn channel 24 in withdrawal direction Z (means for yarn withdrawal).

In an interruption of the spinning process, for example, yarn break or bobbin change, the motor 33 is first stopped, while the discharge cylinder 32 continue at least for a limited period. As a result, the supplied fiber longitudinal structure 10 'is torn between the straps 31 and the outlet cylinders 32 and the downstream piece is conveyed away from the drafting arrangement by the outlet cylinders 32. The downstream piece is possibly disposed of thereon, the means for twist distribution 3 is possibly cleaned.

For the positioning of the free yarn end after an interruption of the spinning process, for example, the upper or lower part of the feed block 25 and the upper or lower of the discharge cylinder 32 can be lifted from their working position, such that the fiber feed channel 26 and the passage between the discharge cylinders 32 for a return and positioning of the yarn end 1 becomes accessible. The yarn end 1, which is unwound from the yarn package or may be an auxiliary yarn (bobbin change) is retracted or returned in such a spinning station for the resumption of the spinning process into the main delay region between center cylinders 30 and 31 and run-out cylinders 32 and hangs freely around the lower of the discharge cylinders 32, where it is monitored by the yarn end sensor 37 (in particular its end 2). When returning through the nozzle block 21 or yarn channel aids, such as a suction device can be used. During the subsequent positioning of the yarn end 1 on the outlet cylinders 32, care must be taken that the yarn end 1 is aligned with the longitudinal fiber structure 10 ', in particular in the clamping point 11 (in the view of FIG FIG. 1 not visible).

The piecing process is carried out in a spinning station, as described in the FIG. 1 If the yarn end 1 is positioned and all the relevant parts of the spinning station are repositioned in their working position, the control unit 34, for example, by personnel or by a piecing robot, the ready signal 35 is transmitted. The control unit then starts the piecing process. That is, the twisting of the means for air twist distribution 3 and the yarn withdrawal (optionally with a predetermined staggering), so that the yarn end 1 begins to move against the twist distribution point. As soon as the yarn end sensor 37 detects the passage of the effective yarn end 2, the control unit receives the yarn end signal 36, by which the actual piecing routine is started. After a delay, firstly by the relative position of the end 2 (detected by the yarn end sensor 37), secondly by the position of the beginning of the end region of the fiber elongated structure 10 '(just before the nip line 11), and third by the desired length overlapping end portions depends on the engine 33 is started. The motor 33 brings the pairs of rollers 30 and 29 within a very short time (hundredths of seconds) to a synchronized with the discharge cylinders 32 speed, so that at the time of overlap of the first fibers of the end portions of yarn end 1 and fiber elongated 10 'the rollers already in the correct speed ratio to each other rotate. The rolls may already have the appropriate nominal or operating speed (ie, the speed of the normal, stationary spinning process) at the beginning of the piecing or piecing process just explained. But it is also conceivable that the piecing or piecing takes place at a lower speed level. Whereupon, after piecing, all the rotating rolls of the refinement unit rise synchronously to their respective nominal or operating speed (eg on a ramp with a gearbox).

For such a piecing routine, it is at most necessary for the control unit 34 to also provide data relating to the starting profile of the outlet cylinders 32, the central cylinders 30 and inlet cylinders 29, and the yarn take-off (not shown) and, if appropriate, measurement data from correspondingly arranged rotational speed sensors.

Optionally, the swirl pitch of the means 3, that is, in the present case, the speed of the air supplied from the nozzles 22 for the production of the Ansetzstelle compared to the normal spinning process changed, for example, be increased for a stronger Faserverwirbelung.

The upstream of an air twist distribution in a spinning unit drafting system 28 may also have only two or more than three pairs of cylinders, wherein at a spinning break an inlet-side part of the cylinder pairs is stopped in front of an outlet side part of the cylinder pairs. In this case, after the spinning interruption, at least the inlet-side part of the cylinder pairs is retarded after a predetermined or determined based on sensor signals ramp. In the FIG. 1 represent the center cylinder 30 and inlet cylinder 29 the inlet side (by motor 33) drivable part of the refinement unit (here drafting system 28), while the outlet cylinder 32 represent the outlet side drivable parts.

• Inbetriebnahme der Verfeinerungseinheit (z.B. Streckwerk) mit den einlaufseitig (z.B. Einlaufzylinder und Mittelzylinder mit Riemchen) und auslaufseitig antreibbaren Teilen (z.B. Auslaufzylinder),
• Zerreissen des Faserlängsgebilde durch Abstellen des Antriebes des einlaufseitig angetriebenen Teiles (Einlauf- und Mittelzylinder) und erst anschliessendem Abstellen des auslaufseitig angetriebenen Teiles (Auslaufzylinder), wobei das Faserlängsgebilde dadurch an einer ziemlich genau durch Versuche bestimmbaren Stelle zwischen beiden Teilen reisst.
• Rückführung eines Garnendes an welchem Angesponnen oder Angesetzt werden soll zuerst durch das Mittel zum Garnabzug, dann durch das Mittel zur Drallerteilung (z.B. Mittel 3) und schliesslich durch das auslaufseitig angetriebene Teil (Auslaufzylinder des Streckwerks)
• Feststellen der Position vom Ende des Garnendes oder Mittel um Festzustellen, wann das Ende des Garnendes eine vorbestimmte Position erreicht hat.
• Inbetriebnahme des Mittels zur Luft-Drallerteilung (z.B. Mittel 3), des Mittels zum Garnabzug und der ein- sowie auslaufseitig angetriebenen Teile der Verfeinerungseinheit

Wobei insbesondere:

• Die Rückführung des Garnendes durch das auslaufseitig angetriebenen Teil der Verfeinerungseinheit durch Öffnen des auslaufseitig angetriebenen Teiles der Verfeinerungseinheit geschieht mit anschliessender
• Positionierung des Garnendes im auslaufseitig angetriebenen Teil der Verfeinerungseinheit fluchtend mit dem Faserlängsgebilde im einlaufseitig angetriebenen Teil.
• Schliessen des auslaufseitig angetriebenen Teiles der Verfeinerungseinheit.
• Die Inbetriebnahme des auslaufseitig angetriebenen Teiles der Verfeinerungseinheit, verbunden mit einem Abzug des Garnendes durch den auslaufseitig angetriebenen Teil (Auslaufzylinder),
• gefolgt von einer zeitlich abgestimmten und verzögerten Inbetriebnahme des einlaufseitig angetriebenen Teiles ist, derart dass sich die Endbereiche des zerrissenen Faserlängsgebilde und des Garnendes überlappen und im überlappenden Zustand die Klemmstelle des auslaufseitig angetriebenen Teiles passieren.

For the piecing or piecing method according to the invention for spinning stations of air spinning machines which produce a yarn from a longitudinal fiber structure in a spinning process, a refinement unit (eg a drafting unit) with parts which can be driven on the inlet side (eg a pre-delay) and outlet side (eg a main delay), wherein at least the outlet side drivable part has a nip. A means for air twist distribution (Vortex) and a means for Garnabzug. After an interruption of the spinning process for the resumption of production of the yarn, the processes according to the invention have the following steps to be carried out in this order (assuming a standstill for all components):

• Commissioning of the refinement unit (eg drafting system) with the inlet side (eg inlet cylinder and center cylinder with straps) and parts which can be driven on the outlet side (eg outlet cylinder),
• Tearing of the fiber longitudinal structure by stopping the drive of the inlet side driven part (inlet and center cylinder) and only subsequent shutdown of the outlet side driven part (discharge cylinder), the fiber longitudinal structure thereby tears at a location determinable by experiments exactly between the two parts.
• Returning a yarn end to which it is intended to be wound or applied first by the means for yarn withdrawal, then by the means for swirl distribution (eg means 3) and finally by the outlet-side driven part (discharge cylinder of the drafting system)
• Detecting the position from the end of the yarn end or means to determine when the end of the yarn end has reached a predetermined position.
• Commissioning of the means for air-twist distribution (eg means 3), the means for Garnabzug and the inlet and outlet side driven parts of the refinement unit

In particular:

• The return of the yarn end by the outlet side driven part of the refinement unit by opening the outlet side driven part of the refinement unit is done with subsequent
• Positioning of the yarn end in the outlet side driven part of the refinement unit in alignment with the longitudinal fiber structure in the inlet side driven part.
• Closing the downstream driven part of the refinement unit.
• The commissioning of the downstream driven part of the refinement unit, connected to a deduction of the yarn end by the outlet side driven part (discharge cylinder),
• followed by a timed and delayed start-up of the intake-side driven part, such that the end regions of the torn fiber longitudinal formation and the yarn end overlap and in the overlapping state pass through the nip of the outlet-side driven part.

• Inbetriebnahme der Verfeinerungseinheit (z.B. Streckwerk) mit den einlaufseitig (z.B. Einlaufzylinder und Mittelzylinder mit Riemchen) und auslaufseitig antreibbaren Teilen (z.B. Auslaufzylinder),
• Zerreissen des Faserlängsgebilde durch Abstellen des Antriebes des einlaufseitig angetriebenen Teiles (Einlauf- und Mittelzylinder) und erst anschliessendem Abstellen des auslaufseitig angetriebenen Teiles (Auslaufzylinder), wobei das Faserlängsgebilde dadurch an einer ziemlich genau durch Versuche bestimmbaren Stelle zwischen beiden Teilen reisst,

sind für den eigentlichen Ansetzvorgang fakultativ, denn es ist anzunehmen, dass bei Produktionsstopp die Spinnstelle zuerst den Antrieb des einlaufseitig angetriebenen Teiles (Einlauf- und Mittelzylinder) und erst anschliessend den auslaufseitig angetriebenen Teil (Auslaufzylinder) abstellt (normaler Prozess).
Diese beiden Schritte müssen also dem Ansetzvorgang vorgegangen sein.It is clear that these steps are to be performed in the order given above. However, the invention is not limited to this order, for example, the step "detecting the position of the end of the yarn end" can be done at different times. Also, the first two steps are:

• Commissioning of the refinement unit (eg drafting system) with the inlet side (eg inlet cylinder and center cylinder with straps) and parts which can be driven on the outlet side (eg outlet cylinder),
• Tearing of the fiber longitudinal structure by stopping the drive of the inlet side driven part (inlet and center cylinder) and only subsequent shutdown of the outlet side driven part (outlet cylinder), the fiber longitudinal structure thereby tears at a determinable by experiments place between both parts,

are optional for the actual piecing, because it is to be assumed that at production stop the spinning station first the drive of the inlet side driven part (inlet and center cylinder) and only then the outlet side driven part (outlet cylinder) turns off (normal process).
These two steps must therefore have proceeded to the piecing process.

According to the invention, the position from the end of the yarn end is detected by means and transmitted to a control, which retards the startup of the inlet side driven part of the refinement unit in such a time when resuming the production of the yarn that the end portions of the torn fiber longitudinal structure and the yarn overlap over a predetermined length ,

According to the invention, the length of the overlapping end regions substantially corresponds to the spinning distance d of the spinning station (see FIG. 1 ). The spinning distance d is defined as the distance between the mouth of the spindle 23 and the nip or clamping point 11 of the outlet cylinder 32nd

It is also possible for this length of the overlapping end regions to be longer than the abovementioned spinning distance d of the spinning station.

In a further variant of the invention, the end region of the yarn end 1 to be overlapped is roughened or tapered.

The spinning station equipped for carrying out the method according to the invention has internal spinning stations its own controllable drive for the inlet-side parts of the refining agent or a correspondingly controllable transmission between these inlet-side parts of the refining means and a central drive.

The other parts of the spinning unit to be driven can be driven by simple coupling to central drives or also by internally spinning, optionally controllable drives.

The invention also includes a spinning station according to the invention of an air-spinning machine. This corresponds constructively to the embodiment according to FIG. 1 , why at this point to the description of FIG. 1 is referred back. The spinning unit according to the invention comprises a refinement unit (drafting unit) with parts which can be driven on the inlet side and outlet side, wherein at least the part which can be driven on the outlet side is equipped with at least one clamping point. Further, the apparatus comprises means for air twisting, a means for yarn withdrawal, with a means for detecting the position of the end of a yarn end. According to the invention, the part of the refinement unit driven downstream can be opened in such a way that its clamping point or clamping points are exposed for a return and positioning of the yarn end.
In a preferred embodiment of the invention, the outlet-side driven part consists of at least one outlet cylinder pair (32), wherein the upper or the lower cylinder of the outlet cylinder pair can be lifted (see arrow and dashed roller in FIG. 1 ).
In a further embodiment of the invention it can be provided that the means for air twist distribution (3) has an effective twist stop (27) for the yarn end. As an example, a mandrel 27 is shown here. The special feature is that the twist stop (27) is effective for the yarn end and not only for the fiber longitudinal structure. This results in very good piecing.
In the claims further embodiments of the invention are listed.

It would also be conceivable that instead of the nip 11 of the discharge cylinder 32, an additional device takes over the function of the nip, ie the compression of the overlapping end portions of yarn end (1) and longitudinal fiber structures (10 ') for the piecing process. Such a device would then swing away.

The invention is not limited to the explicitly stated possibilities and embodiments. These variants are intended rather as a suggestion for the expert to implement the idea of the invention as low as possible. Of the described embodiments, therefore, further advantageous applications and combinations are readily derivable, which also reflect the inventive concept and should be protected by this application.

Claims (4)

1. Method for starting the spinning process or piecing-method for spinning positions of air spinning frames, which, during a spinning process, produce a thread (11) from a longitudinal fibre structure (10') and which, therefor, comprise a drafting unit (28) with drivable parts at the inlet side (30, 29) and at the outlet side (32) with clamping points (11), a means for generating an air twist (3) and a means for the thread take-off, whereby, after an interruption of the spinning process, the resumption of the production of the thread comprises the following steps,

   - return of a thread end (1) at which the spinning has to be started or the piecing has to take place, first by the means for the thread taking-off, then by the means for generating a twist (3) and finally by the driven part at the outlet side (32) of the drafting unit (28)

   - determination of the position of the end (2) of the thread end (1)

   - -starting-up of the means for generating the air twist (3), the means for the thread take-off and the parts of the drafting unit (28)

   - the return of the thread end (1) takes place through the driven part (32) at the outlet side of the drafting unit, by opening the driven part (32) of the drafting unit at the outlet side, whereby, afterwards the thread end (1) is positioned In the driven part (32) at the outlet side of the drafting unit driven In alignment with the longitudinal fibre structure (10') in the driven part at the inlet side, and afterwards

   - the driven part (32) at the outlet side of the drafting unit (28) is being closed again, and

   - the starting-up of the driven part (32) at the outlet side of the drafting unit (28) takes place with a subsequent time co-ordinated and delayed start-up of the driven parts (30, 29) at the inlet side, in such a manner that the end portions of the torn longitudinal fibre structure (10') and of the thread end (1) overlap and pass, in overlapping condition, the clamping point (11) of the driven part (32) at the outlet side,

   whereby the position of the end (2) of the thread end (1), being registered by means (37), is transmitted to a control unit (34), which, with the resumption of the production of the thread, delays the starting-up of driven the part (30, 28) of the drafting unit (28), at the inlet side, timed in such a manner that the end portions of the torn longitudinal fibre structure (10') and of the thread end (1) overlap over a predetermined length, characterized in that,
   the length of the overlapping end portions essentially corresponds with the spinning distance (d) of the spinning position or the length of the overlapping end portions is longer than the spinning distance (d) of the spinning position, whereby, the spinning distance "d" is defined as the distance between the port of the spindle (23) and the clamping line or the clamping point (11) of the output cylinder (32).
2. Method according to claim 1, characterized in that the step, concerning the return of the thread end (1) at which the start of spinning or the piecing has to take place, is preceded by the following two steps

   - starting-up of the drafting unit (28) with the drivable parts (30, 29) at the inlet side and the drivable parts (32) at the outlet side,

   - tearing of the longitudinal fibre structure (10') by stopping the drive unit (33) of the driven part (30, 29) at the inlet side and only by subsequently stopping the driven part (32) at the outlet side.
3. Spinning position of an air spinning frame containing a drafting unit (28) with drivable parts (29, 30) at the inlet side and drivable parts (32) at the outlet side , whereby at least the drivable part (32) at the outlet side is furnished with at least one clamping point (11), with a means for generating an air twist (3), a means for the thread taking-off, with a means (37) for the determination of the position of the end (2) of the thread end (1), characterized in that

   - the driven part (32) at the outlet side of the drafting unit (28) can be opened in such a manner, that its clamping point (11) or clamping points lies free for a return and a positioning of the thread end (1) and that the spinning position comprises a control means (34) for carrying out the start of the spinning or the method of piecing according to claim 1.
4. Device according to claim 3, characterized in that the drafting unit (28) is a drafting unit and that the driven part (29, 30) at the inlet side realises a pre-draft and that the driven part (32) at the outlet side represents the outlet clamping line (11) of the drafting unit.

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