EP1219737B1 - Procedure for piecing up or joining a yarn created in a spinning station, said spinning station being equiped to carry out the procedure - 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 for preparing a yarn which is formed in a spinning machine or in a spinning unit of a 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 disturbance. 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.

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 various methods are known: e.g. Ring spinning, pot spinning, bell spinning, friction spinning, rotor spinning, air spinning etc.

After an interruption of the spinning process, in which the connection between the spun yarn and the to be spinned, refined fiber structure 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 can. For such a reconnection of yarn and fiber structure, in particular in air-spun processes, the free yarn end resulting from the interruption is moved upstream of the normal yarn conveying direction upstream of the yarn Drallerteilungsstelle pulled out and positioned. Then, the yarn take-off and twist pitch are put back into operation and the free beginning of the refined fiber strand is fed to the twist pitch such that during a short transition time, the end area of the yarn and the beginning area of the fiber strand move 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 connected to the end region of the yarn in a kind of splice, whereby the spinning process is again normally operable.

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.

• Damit die Ansetzstelle eine störungsfreie Fortsetzung des Spinnvorganges erlaubt, muss diese selbst und ihre Umgebung eine für diesen Zweck genügend grosse Reissfestigkeit aufweisen, das heisst üblicherweise, dass diese Reissfestigkeit mindestens so gross sein soll, wie die Reissfestigkeit des im vorliegenden Spinnvorgang hergestellten Garnes.
• Damit die Ansetzstellen die Garnqualität nicht mindern, darf die Fasermasse pro Längeneinheit in der Ansetzstelle und in deren Umgebung nur in vorgegebenen, meist engen Grenzen von der Fasermasse pro Längeneinheit des im vorliegenden Spinnvorgang hergestellten Garnes abweichen.

The following requirements are made of the placement point that results when setting or piecing according to the method briefly described above:

• 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.
• Thus, the Ansetzstellen do not reduce the yarn quality, the pulp per unit length in the Ansetzstelle and in their environment may differ only in predetermined, usually narrow limits of the fiber mass per unit length of the yarn produced in the present spinning process.

In other words, the piecing points to be made in the case of spinning breaks should differ as little as possible from the other areas of the yarn produced in terms of strength and fiber mass per unit length. They should be as little as possible visible or otherwise detectable and they should the further use of the yarn, starting with the continuation of the spinning process, as little as possible influence.

There are several methods known which try to get closer to the above mentioned goals. 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 known, for example, from the publication DE-4240653-A1 to roughen the yarn end region or to detach fiber ends from the dense fiber structure of the yarn and to spread them off from the yarn, thereby improving the turbulence with the newly added fibers and increasing the tensile strength of the application point becomes.

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 in an overlapping manner for splicing with a correspondingly tapered beginning of a longitudinal fiber structure (gradually increasing fiber mass).

The use of a "tapered" starting region of a fiber dressing for setting is described, for example, in 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 starting area of the Fiber elongate, which is believed to have a tapered shape as a result of the tearing, 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 is further refined according to the publications US-5809764 and US-5934058 (both Murata), in that the tapered initial region of the fiber longitudinal structure is shortened by stretching a small piece before stretching and in that in one Air draft, which is used between drafting and twist distribution point, 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 highest standards. The used according to the methods mentioned yarns tend to have a weak point with a too small fiber mass immediately after a piecing or the pulp is too large in the Ansetzstelle.

For this reason, usually the Ansetzstelle is given with a relation to the remaining yarn up to 200% increased fiber mass for piecing sure enough tear resistance and the Ansetzstellen, which can be up to 200 mm long, subsequently detected with a yarn cleaner and subsequently created splice replaced. This is obviously a very expensive process.

The object of the invention is now to show a method for setting or piecing, with which method Ansetzstellen can be produced, which are able to meet higher demands both in terms of strength and with respect to fiber mass, as is the case for Ansetzstellen prepared according to known methods. Furthermore, it is the object of the invention to provide a spinning station, which is equipped for carrying out the inventive method.

These objects are achieved by the method and the spinning station as defined in the claims.

The method according to the invention is based on the finding that usually an initial region produced by disruption of the spinning process by tearing of a longitudinal fiber structure has no substantial taper and / or that such an initial region is not sufficient to produce a satisfactory piecing point even after stretching. Thus, according to the method according to the invention, an initial region resulting from tearing and thereby, if necessary, tapering is not subjected to a normal distortion, but an initial region with an increasing fiber mass is formed in a targeted manner by appropriate control of the distortion in the refinement step. For this purpose, in the resumption of the spinning process during a piecing advantageously the collection of fiber longitudinal pattern in the refinement controlled so matched to the outlet of the refined fiber structure from the refinement that the delay gradually decreases and thereby the leaking fiber structure over its length gradually increasing fiber amount having. It is thus ensured essentially by an inlet control that the delay in the refinement step gradually decreases (increasing inlet velocity) until it assumes a suitable value for a normal spinning process. The rate of emergence of the refined fiber aggregate from refining (or delivery rate to yarn formation) may be constant during the time of decreasing warpage or may be gradually increased to accommodate a corresponding increase in yarn formation speed for easy piecing.

The time during which the warp of the fiber elongate drawn into the refinement is reduced to a normal value, and the velocity profile of this warp reduction is to be matched to the length and shape of the tapered yarn end portion. The movement of the yarn end region through the twist distribution point is timed to match the movement of the initial region of the fiber structure delivered from the refinement, that the two tapered areas are moved as completely as possible overlapping each other by the twist distribution and complement each other to a pulp that deviates as little as possible from the fiber mass of the created during the normal spinning yarn.

A spinning station equipped for carrying out the method according to the invention has, like known spinning stations, a refining agent, a twisting agent and a yarn draw-off agent. In this case, inlet parts of the refining agent are controllable independently of outgoing parts of the refining agent for a piecing routine, which piecing routine consists essentially of gradually reducing the delay which the fiber longitudinal formation undergoes in the refining medium from an increased value to a normal value. The outgoing side portions of the refining means and the means for yarn withdrawal may be operated at normal speeds during the piecing routine or may also undergo a piecing routine at gradually increasing rates.

The spinning station equipped for carrying out the method according to the invention therefore has its own internally controllable drive for the inlet-side parts of the refining means or a correspondingly controllable transmission between these inlet-side parts of the refinement 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 spinning station is further equipped in a conventional manner for that the free yarn end can be positioned upstream of the twist distribution point and timed with the re-commissioning of the refining agent, and for the fact that the supplied fiber longitudinal structure before the resumption of the spinning process in a well-defined as possible and advantageously of exactly reproducible kind is separated or torn.

Figur 1

eine nach dem erfindungsgemässen Verfahren hergestellte Ansetzstelle;

Figur 2

ein Schema einer Anspinnroutine zur Durchführung des erfindungsgemässen Verfahrens;

Figuren 3 und 4

im Schnitt schematisch dargestellte Beispiele von Spinnstellen, die für die Durchführung des erfindungsgemässen Verfahrens ausgerüstet sind.

The inventive method and the spinning station according to the invention will be described in detail with reference to the following figures. Showing:

FIG. 1

a Ansetzstelle prepared by the inventive method;

FIG. 2

a diagram of a piecing routine for carrying out the inventive method;

FIGS. 3 and 4

in section schematically illustrated examples of spinning stations, which are equipped for carrying out the inventive method.

FIG. 1 very schematically shows a tapered, free end region 1 of a yarn 11 to be drawn off in draw-off direction A and a free starting region 2 of a refined fiber structure 10 fed in the feed direction Z with a fiber mass adapted to the rejuvenation of the yarn, the end region 1 of the yarn 11 and the initial region 2 of the fiber structure 11 overlap for a piecing process. Furthermore, the figure shows a result of the connection of the two areas 1 and 2 Ansetzstelle 3 in the finished yarn.
The yarn end region 1 has a fiber mass which decreases towards the yarn end over a taper length L.1. The fiber composite starting region 2 is substantially adapted to the taper of the end region of the yarn 11, wherein the tapers may be continuous or more or less stepped, and has approximately the same length L.2. The lengths L.1 and L.2 are for example about 80 mm. The overlap of yarn end region 1 and fiber strand starting region 2 is advantageously such that the fiber mass in the application point 3 is slightly larger than in the normally spun yarn. With this increase in the fiber mass, the slightly reduced fiber adhesion can be made up in the piecing station 3. It can be seen that with the method according to the invention, piecing points can be produced which have sufficient tear resistance and which at no point have a fiber mass which is more than about 20% higher than the average fiber mass per unit length of the yarn. In particular, neither in the Ansetzstelle still be expected in the immediate vicinity with places a much reduced fiber mass and thus with reduced tensile strength.

Figure 2 shows very schematically the control of the piecing routine according to the inventive method. On the left, the spinning process is shown, in which a fiber longitudinal structure 10 'is fed, drawn into a refined fiber structure 10 and spun into a yarn 11. The fibers thereby pass through a refinement inlet 12 (optionally combined with a pre-refinement), a refinement outlet 13 and the yarn formation 14 (twist distribution and yarn withdrawal).

On the left, the speeds G.1 (run-in speed), G.2 (run-off or delivery speed) and G.3 (yarn take-off speed) of the three stages are shown on a respective time axis and in particular their change in the case of an interruption of the spinning process and a subsequent piecing routine according to FIG Invention. During a normal spinning process, these velocities, as shown in Figure 2 prior to time t.1, are constant or vary in a concerted manner. The ratio of G.1 and G.2 essentially determines the delay of the refinement step, the ratio of G.2 and G.3 the spin delay.

The time t.1 marks an interruption of the spinning process (can change, bobbin change, spinning disturbance) and the period between the times t.3 to t.5 or t.6 the piecing routine. Between interruption and Anspinnroutine is an interruption of the spinning process, in which the measures necessary for the restart of the spinning process are carried out, in particular the preparation of the free yarn end and its positioning upstream of the twist distribution point. This interruption may vary depending on the reason for the interruption and depending on the machine equipment.

t.1:

Anhand eines entsprechenden Unterbrechungssignals werden der Verfeinerungseinlauf 12 und die Garnbildung 14 (insbesondere der Garnabzug, gegebenenfalls auch die Drallerteilung) gestoppt.

t.1 bis t.2:

das zugeführte Faserlängsgebilde 10 wird an einer definierten Stelle zwischen Einlauf und Auslauf zerrissen und das abgerissene Stück aus der Verfeinerung läuft aus der Verfeinerung aus und kann entsorgt werden.

t.2:

Mit einer vorgegebenen Verzögerung gegenüber dem Verfeinerungseinlauf 12 wird auch der Verfeinerungsauslauf 13 gestoppt.

t.3:

Nach Durchführung der zur Wiederaufnahme des Spinnprozesses notwendigen Massnahmen, insbesondere nach der Positionierung des entsprechend vorbereiteten freien Garnendes mit Verjüngung werden der Verfeinerungsauslauf 13 und die Garnbildung 14 (insbesondere der Garnabzug) wieder in Betrieb genommen und zwar im wesentlichen sofort mit Geschwindigkeiten, wie sie für den normalen Spinnprozess eingestellt werden (durchgezogene Linien), oder nach einer Ansprinnroutine, die beispielsweise eine Geschwindigkeitssteigerung über eine vorgegebenen Zeit vorsieht (unterbrochene Linien). Vom Zeitpunkt t.3 an bewegt sich das Garnende gegen die Drallerteilung.

t.4:

Der Verfeinerungseinlauf 12 wird gestartet. Der Zeitpunkt t.4 wird für eine genaue zeitliche Übereinstimmung der Bewegungen von Garn-Endbereich und Faserverband-Anfangsbereich vorteilhafterweise durch sensorische Überwachung des Garnendes bestimmt. Dieses wird vom Zeitpunkt t.3 an gegen die Drallerteilung abgezogen und erzeugt ein Signal, wenn es eine vorgegebene Position erreicht. Der Zeitpunkt t.4 ist gegenüber dem Garnende-Signal verzögert, wobei die Verzögerung im wesentlichen durch die Position des Garnende-Sensors und des Anfangs des Faserlängsgebildes und durch die Länge (L.1, Figur 1) des sich verjüngenden Garnendes bestimmt ist.

t.4 bis t.5:

Während diesem Zeitraum wird die Geschwindigkeit des Verfeinerungseinlaufs 12 allmählich erhöht und erreicht zum Zeitpunkt t.5 einen Wert, der zusammen mit der momentanen Auslaufgeschwindigkeit den vorgegebenen (normalen) Verzug ergibt. Während dem Zeitraum t.4 bis t.5, dessen Länge auf die Länge (L.1, Figur 1) des vorbereiteten, sich verjüngenden Garnendbereichs abgestimmt ist, entsteht durch die relativ zur Auslaufgeschwindigkeit zunehmende Einlaufgeschwindigkeit eine Abnahme des Verzugs und damit die steigende Fasermasse des Faserverband-Anfangsbereichs (2, Figur 1).

t.5:

Zu diesem Zeitpunkt hat für die ausgezogen dargestellte Variante die Einlaufgeschwindigkeit den normalen Wert erreicht und die Anspinnroutine ist damit beendet.

t.5 bis t.6:

für die gestrichelt dargestellte Variante ist in diesem Zeitraum die Spleissung wie für die ausgezogen dargestellte Variante zwar beendet, wird aber noch die Spinngeschwindigkeit (G.1, G.2, G.3 und gegebenenfalls auch die Drallerteilungsgeschwindigkeit) auf ihren Normalwert hochgefahren, wobei die einzelnen Geschwindigkeiten sich zueinander verhalten wie während dem normalen Spinnprozess. Die Anspinnroutine gemäss der gestrichelt dargestellten Variante ist zum Zeitpunkt t.6 beendet.

Spin interruption and piecing routine take place according to the inventive method for the successive steps of the spinning process as follows:

t.1:

Based on a corresponding interrupt signal, the refinement inlet 12 and the yarn formation 14 (in particular the yarn take-off, possibly also the twist distribution) are stopped.

t.1 to t.2:

the supplied fiber longitudinal structure 10 is torn at a defined point between inlet and outlet and the torn piece of the refinement comes out of the refinement and can be disposed of.

t.2:

With a predetermined delay relative to the refinement inlet 12, the refinement outlet 13 is also stopped.

t.3:

After carrying out the necessary measures to resume the spinning process, in particular after the positioning of the corresponding prepared free yarn end with taper the refining spout 13 and the yarn formation 14 (in particular the yarn take-off) are put back into operation, namely substantially immediately at speeds as they are for the normal spinning process are set (solid lines), or after a Ansprimmerroutine, for example, provides an increase in speed over a given time (broken lines). From time t.3, the yarn end moves against the twist pitch.

t.4:

The refinement enema 12 is started. The point in time t.4 is advantageously determined by a sensory monitoring of the yarn end for an exact coincidence of the movements of the yarn end region and fiber strand starting region. This is deducted from the time t.3 against the twist distribution and generates a signal when it reaches a predetermined position. The time t.4 is delayed from the yarn end signal, the deceleration being essentially determined by the position of the yarn end sensor and the beginning of the fiber longitudinal structure and by the length (L.1, Figure 1) of the tapered yarn end.

t.4 to t.5:

During this period, the speed of the refinement inlet 12 is gradually increased and reaches a value at time t.5 which, together with the instantaneous exit speed, gives the predetermined (normal) delay. During the period t.4 to t.5, the length of which is tuned to the length (L.1, FIG. 1) of the prepared, tapering yarn end region, a decrease in the warping and thus the rising fiber mass is produced by the inlet speed increasing relative to the outlet speed of the fiber-band beginning region (2, FIG. 1).

t.5:

At this time, the run-in speed has reached the normal value for the variant shown in solid lines, and the piecing routine is thus ended.

t.5 to t.6:

for the variant shown in dashed lines, the splice is completed during this period as for the variant shown extended, but still the spinning speed (G.1, G.2, G.3 and possibly also the twisting speed) is raised to its normal value, the individual velocities to each other behave as during the normal spinning process. The piecing routine according to the variant shown in broken lines is completed at time t.6.

Possible variants of piecing routines, as illustrated in FIG. 2, consist, for example, in the fact that the attenuation outlet 13 is not stopped at all during the spinning interruption (t.1 or t.2 to t.3). Another variant is that the yarn formation 14 (in particular the yarn withdrawal) are stopped only with the outlet 13 at time t.2 or even later. Another variant is that the piecing routine relating to yarn formation is shorter than the time required for the preparation of the piecing location (t.6 before t.5).

To control the piecing routine, a control unit is provided. These are to provide data on the length and profile of the taper of the yarn end region or to transmit corresponding measurement data of a mass sensor on-line, which mass sensor detects the fiber mass of the yarn end region. The control unit controls at least the speed of the refinement entry to perform the piecing routine.

FIG. 3 shows an exemplary embodiment of a spinning station for carrying out the method according to the invention. This spinning station is equipped for a so-called air spinning process with refinement by stretching. The spinning station has for twisting a nozzle block 21 with therein admitted nozzles 22, a spindle 23 with a yarn channel 24 and a feed block 25 with a fiber feed channel 26 and a directed against the entrance of the yarn channel 24 needle 27. For refinement, the spinning station 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).

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 utilizes a ready signal 35 and a yarn end signal 36 of a yarn end sensor 37 for controlling the motor 33, as well as spinning unit-specific parameters and data relating to the tapering of the yarn end region.

During the spinning process known per se in the spinning station according to FIG. 3, the fiber longitudinal formation 10 'fed between the inlet cylinders 29 enters the refinement between the inlet cylinders 29, and is biased between inlet cylinders 29 and center cylinders 30 with a usually constant stretching ratio and between central cylinders 30 and Auslaufzylindern 32 subjected to a main delay with 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. That through this twist distribution resulting yarn 11 is withdrawn through the yarn channel 24 in the withdrawal direction Z (withdrawal means not shown).

When the spinning process is interrupted, the motor 33 is stopped while the outlet cylinders 32 continue to run for at least a limited period of time (t.1 to t.2, FIG. 2). 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 carried away from the drafting system by the outlet cylinders 32, so that it can be disposed of.

For the known per se positioning of the free yarn end after an interruption of the spinning process, for example, the upper part of the feed block 25 and the upper of the discharge cylinder 32 are lifted from its working position, such that the fiber feed channel 26 and the passage between the discharge cylinders 32 for positioning the Garn Endbereiches 1 is accessible. The yarn end portion 1 is retracted in such a equipped spinning station for the resumption of the spinning process into the main drafting area between center cylinders 30 and 31 and Auslaufzylindern 32 hanging freely around the lower of the discharge cylinder 32, where it is monitored by the yarn end sensor 37 ,

The yarn end portion 1 can be positioned for the resumption of the spinning process after an interruption also between the discharge cylinders 32 and the feed block 25 or between the feed block 25 and the nozzle block 21, wherein for the latter case between the two blocks 25 and 21, a corresponding gap must be provided, through which the yarn end portion 1 can be positioned and then easily removed. These two variants are indicated by dash-dotted lines in FIG. 3 and the correspondingly positioned yarn end regions are denoted by 1 'and 1 ". The yarn end sensor 37 is to be correspondingly positioned for the variants mentioned.

The piecing routine, as shown in solid line in FIG. 2, is controlled in a spinning station, as shown in FIG. 3, as follows: When the yarn end (1, 1 'or 1 ") is positioned and all relevant parts of the spinning station in FIG are repositioned to their working position, the control unit 34 is notified, for example by personnel or by a piecing robot, of the ready signal 35. The control unit thereupon starts the finishing run, the twist pitch and the yarn take-off (possibly with a predetermined stagger) so that the yarn end begins to bear against the As soon as the yarn end sensor 37 detects the passage of the effective yarn end, the control unit receives the yarn end signal 36, which starts the actual piecing routine, according to a signal determined by the relative position of the yarn end sensor 37 and the beginning of the fiber longitudinal structure (FIG. relevant spinning station-own parameters) and by the L At the predetermined deceleration of the prepared tapered yarn end region, the motor 33 is started and ramped up after a ramp adapted to the taper profile of the yarn end region.

In order for the said ramp to be predetermined, it is necessary for prepared yarn end regions to have a reproducible and precisely known taper. If this is not the case, it is also possible to use an appropriately positioned mass sensor to measure the yarn end area on-line and to control the increase in the inlet speed based on the generated measurement signal. For example, the yarn end sensor 37 can also take over the function of the mass sensor.

For a piecing routine, as shown in phantom in FIG. 2, the control unit 34 is also provided with data relating to the starting profile of discharge cylinders 32 and yarn take-off and optionally measurement data from correspondingly arranged rotational speed sensors.

Optionally, the twist distribution, that is, in the present case, the speed of the air supplied from the nozzles 22 for the production of the Ansetzstelle changed over the normal spinning process, for example, be increased for a stronger Faserverwirbelung.

The upstream of a 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 interruption an inlet side of the pair of cylinders is stopped before an outlet side of the pair of cylinders and wherein after the spinning interruption at least the inlet-side part of the cylinder pairs after a is ramped up or determined based on sensor signals ramp.

From the above description of the spinning station shown in Figure 3 shows that the piecing routine according to the inventive method in particular the refinement and that the effective yarn formation is not affected in many cases. For this reason, the method according to the invention for setting or piecing can also be used without problems for other spinning processes.

FIG. 4 shows a spinning station in which the twist distribution is again realized by a turbulent flow, as has already been described in connection with FIG. The supplied fiber longitudinal structure 10 'but is not refined by stretching in a drafting but by a fiber separation. The refining agent thus has a feed roll 40 and an opening roller 41 and may further comprise a suction roll 42 and a take-off roll 43. The spinning station shown in FIG. 4 and in particular the refinement agent and its function are described in Swiss Patent Application No. 0753/00 (Obj. 2828). The delay occurs between the feed roller 40 and the opening roller 41. The following on the opening roller 41, further rollers are used for the separation of dirt and the collection of isolated fibers to a fiber structure. In any case, the feed roller 40 constitutes the refinement inlet and the further rollers (41, 42, 43) following the feed roller 40 complete the refinement outlet.

In a spinning break, the feed roller 40 (motor 33) is stopped and the opening roller 41 and the optionally following rollers 42 and 43 as long continue to operate until they are substantially free of fibers. Then, the prepared yarn end 1 is positioned, for example, around the suction roll 42 (or between feed block 25 and suction roll 42, or between die block 21 and feed block 25) in which region the yarn end sensor 37 is located. After carrying out these measures enabling the resumption of the spinning process, all parts of the spinning station are taken up to the feed roller 40 and operated at speeds that are usual for a normal spinning process. Thus, the yarn end begins to move against the twist distribution point. The feed roller is started after the yarn end signal and a suitably long delay and its speed is increased via a suitable ramp, as described in connection with FIG. 3 for the intake and center cylinders of the drafting system.

For a piecing routine according to the variant shown by dashed lines in FIG. 2, the description of FIG. 3 is applicable accordingly.

Claims (18)

1. Method for piecing or for starting spinning after an interruption in a spinning process in a spinning station of a spinning machine, in which spinning process a longitudinal fibre structure (10') is refined by means of a draft having a predetermined value, from which refined fibre composite (10) a yarn (11) is produced by a twist being imparted and the yarn (11) is taken off from the imparting of the twist, for piecing or for starting spinning the longitudinal fibre structure (10') being torn apart between a refinement entry and a refinement exit, a tapering yarn end region (1) being produced at a free yarn end, the free yarn end being positioned upstream of the imparting of the twist, and a fibre-composite initial region (2) and the yarn end region (1) being supplied, coordinated with one another in time, to the imparting of the twist, in such a way that they are subjected, overlapping one another, to the imparting of the twist, characterized in that, to produce in the fibre-composite initial region (2) a fibre mass which increases in adaptation to the taper of the yarn end region (1), the draft of the longitudinal fibre structure (10) is reduced in an initial phase of the spinning process from an increased value to the predetermined value.
2. Method according to Claim 1, characterized in that data relating to the length and profile of the tapering yarn end region (1) or measurement data from a mass sensor recording the fibre mass of the yarn end region (1) on-line are used for controlling the reduction in the draft.
3. Method according to Claim 1 or 2, characterized in that, to reduce the draft, the speed (G.1) of the refinement entry is increased until the ratio of the speeds (G.1 and G.2) of the refinement entry and refinement exit results in a draft having the predetermined value.
4. Method according to one of Claims 1 to 3, characterized in that the speeds (G.2 and G.3) of the refinement exit and of the yarn take-off are kept constant during the increase in the speed (G.1) of the refinement entry.
5. Method according to one of Claims 1 to 3, characterized in that the speeds (G.2 and G.3) of the refinement exit and of the yarn take-off are also increased during the increase in the speed (G.1) of the refinement entry.
6. Method according to one of Claims 1 to 5, characterized in that the reduction in the draft is initiated by means of a sensor-determined yarn-end signal (36).
7. Method according to one of Claims 1 to 6, characterized in that an eddy flow is used for imparting the twist.
8. Method according to one of Claims 1 to 7, characterized in that the refinement is a drafting between successive pairs of cylinders (29, 30, 32).
9. Method according to Claim 7, characterized in that the drafting comprises a predraft and a main draft, the predraft remaining unchanged during the reduction in the draft.
10. Method according to one of Claims 1 to 7, characterized in that the refinement comprises fibre separation by means of an opening roller (41), and in that, to reduce the draft, the speed of a feed roller (40) feeding the longitudinal fibre structure (10') to the opening roller (41) is increased.
11. Spinning station of a spinning machine, with a refinement means which has entry-side and exit-side driveable parts, with a means for imparting a twist and with a means for yarn take-off from the imparting of the twist, characterized in that the entry-side parts (29 and 30, 40) of the refinement means can be driven in a controlled manner independently of other parts (32, 41 and 42) of the refinement means and of the spinning station and independently of other spinning stations, and in that the spinning station has a control means (34), by which the speeds of the entry-side parts (29 and 30, 40) of the refinement means can be increased according to a predetermined profile or on the basis of sensor-detected data.
12. Spinning station according to Claim 11, characterized in that exit-side parts (32, 41 and 42) of the refinement means and the means for yarn take-off can also be driven, independently of other parts, for carrying out a spinning start routine.
13. Spinning station according to Claim 11 or 12, characterized in that the spinning station has a yarn-end sensor (37) for initiating a spinning start routine.
14. Spinning station according to one of Claims 11 to 13, characterized in that the control means (34) is equipped for receiving a readiness signal (35) and/or further data and for the corresponding adaptation of the spinning start routine.
15. Spinning station according to one of Claims 11 to 14, characterized in that the means for imparting a twist has nozzles (22) which are arranged for generating an eddy flow.
16. Spinning station according to one of Claims 11 to 15, characterized in that the refinement means is a drafting arrangement (28) with at least two pairs of cylinders (29, 30, 32), and in that the speed of at least one pair of entry cylinders (29) can be increased in a controlled manner.
17. Spinning station according to Claim 16, characterized in that the drafting arrangement has a pair of entry cylinders (29), a pair of middle cylinders (30) with aprons (31) and a pair of exit cylinders (32), and in that the speed of the entry cylinders (29) and of the middle cylinders (30) with the aprons (31) can be increased in a controlled manner.
18. Spinning station according to one of Claims 11 to 15, characterized in that the refinement means has a feed roller (40) and an opening roller (41), and in that the speed of the feed roller (40) can be increased in a controlled manner.

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