EP4389948A1 - Fiber tape preparation - Google Patents

Abstract

The invention relates to a drafting system for conveying a fiber sliver in the direction of an inlet opening of a vortex chamber of an air spinning device and to a method for operating a drafting system having an output roller pair and at least one further drafting system roller pair and/or apron roller pair, by means of which a fiber sliver for producing a thread is fed to a vortex chamber of an air spinning device of the spinning station at a spinning station of an air spinning machine, wherein the output roller pair can be driven decoupled from the at least one further drafting system roller pair and/or apron roller pair. In order to provide a method for operating a drafting system having an output roller pair and at least one further drafting system roller pair and/or apron roller pair, as well as a drafting system which enables reliable preparation of the sliver end before the piecing process, it is provided that the output roller pair is driven at a predetermined combing speed for combing out the sliver end after a spinning interruption and that the at least one drafting system roller pair and/or apron roller pair arranged upstream of the output roller pair in the direction of fiber sliver travel is stopped or operated at a holding speed assigned to the combing speed, which is a maximum of 10% of the combing speed.

Description

The invention relates to a drafting system for conveying a fiber sliver in the direction of an inlet opening of a vortex chamber of an air spinning device and to a method for operating a drafting system having an output roller pair and at least one further drafting system roller pair and/or apron roller pair, by means of which a fiber sliver is fed to a vortex chamber of the air spinning device at a spinning station of an air spinning machine for producing a thread, wherein the output roller pair can be driven decoupled from the at least one further drafting system roller pair and/or apron roller pair.

Generic drafting systems and methods for operating them at a spinning station of an air-jet spinning machine are known in a variety of designs from the prior art. At the spinning stations of such air-jet spinning machines, the drafting systems serve to feed a fiber sliver to a vortex chamber of an air-jet spinning device of the spinning station, which is previously drawn.

During the spinning process, errors occur again and again, resulting in thread sections whose parameters, such as thread thickness, hairiness, thread strength, etc., deviate from a specified target value. Such thread errors are detected by a thread sensor and must be removed in a cleaning cut that interrupts the spinning process. Thread breaks also occur during the spinning process, where the thread tears, which also requires the thread end to be reattached to the fiber sliver fed to the air spinning machine in the vortex chamber by the drafting system.

In order to carry out the piecing process, it is necessary to pick up the respective thread end that has run onto a winding bobbin from the winding bobbin using a thread take-up device that is either provided on the spinning station or can be moved past the spinning station, in particular one that can be moved on the air spinning machine, in order to transfer it into the swirl chamber of the air spinning device against the actual direction of the thread during the spinning process, in order to be able to connect it there with the fed fiber band. In order to prepare the thread end for connection with the fed fiber band, it is necessary to prepare the thread end for connection with the fiber band before piecing. This is done using a thread preparation device that is located in the swirl chamber in It is located downstream of the thread path and is used to cut the thread end to a predefined length and to unravel the thread end, i.e. to free it from its existing twist so that it can be connected to the supplied fiber band. After the thread end has been unraveled, it is transported to the vortex chamber and held there by releasing a clamp that positions the thread end in the thread preparation device, for example by means of blowing air.

In the piecing process that then takes place, the sliver is fed to the vortex chamber via the drafting system over the output roller pair, which is connected to the free thread end placed there to form a thread in the vortex chamber and is then drawn off from the vortex chamber via the draw-off device.

At the start of the piecing process, the drafting system is first raised, which transports the sliver towards the swirl chamber. The take-off device is only started after the drafting system has started to raise itself, so that at the start of the piecing process the yarn end has a dwell time in the swirl chamber during which the sliver fed in via the drafting system is connected to the yarn end in the swirl chamber. After the dwell time has elapsed, both the take-off device and the pair of output rollers are accelerated to a predetermined take-off speed, at which the spinning process is then continued.

Careful preparation of the free fiber sliver end is particularly important for a faultless connection of the thread end to the fiber sliver during the piecing process. However, known drafting systems and methods for fiber sliver preparation using these drafting systems only allow the desired conditioning of the fiber sliver end before the piecing process to a limited extent.

Proceeding from this, the object of the invention is to provide a method for operating a drafting system having an output roller pair and at least one further drafting system roller pair and/or apron roller pair, as well as a drafting system which enables reliable preparation of the sliver end before the piecing process.

The invention solves the problem by a method having the features of claim 1 and by a drafting system having the features of claim 4. Advantageous developments of the Method are specified in the dependent claims 2 and 3. Further embodiments of the drafting system according to the invention can be found in the dependent claims 5 and 6.

A characteristic feature of the method according to the invention is that the output roller pair for combing out the fiber sliver is driven at a predetermined combing out speed after a spinning interruption and the at least one pair of drafting rollers and/or apron rollers arranged upstream of the output roller pair in the direction of fiber sliver travel is stopped or operated at a holding speed associated with the combing out speed, which is max. 10% of the combing out speed.

In regular spinning operation, the output roller pair of the drafting system and the take-off device have a matching production speed, referred to as the take-off speed, whereby the at least one pair of drafting system rollers and/or apron rollers upstream of the output roller pair in the direction of thread travel has a lower production speed due to the system in order to achieve the desired draft of the fiber sliver within the drafting system.

According to the method according to the invention, it is provided that the output roller pair, which can be driven decoupled from the at least one further pair of drafting system rollers and/or apron rollers, is driven at a predetermined combing speed, while the at least one further pair of drafting system rollers and/or apron rollers upstream is stationary or is operated at a low holding speed that is max. 10% of the combing speed. Such a combing operation of the drafting system results in no or only a very small feed of the fiber sliver in the direction of the vortex chamber of the air spinning device. Rather, especially when the pairs of drafting system rollers and/or apron rollers are stationary and the output roller pair is operating at the predetermined combing speed, the fiber sliver end is conditioned by this combing process so that it can be optimally prepared for the piecing process onto the free thread end arranged in the vortex chamber.

According to a further development of the invention, the output roller pair is positioned at the start-up of the drafting system during piecing before the at least one another pair of drafting rollers and/or apron rollers. This embodiment of the invention makes it possible to avoid fluctuations when the output roller pair is raised, as a result of which fibers are not conveyed at the speed specified by the rest of the drafting system and which can lead to additional distortion of the fiber sliver or a build-up of the fibers.

In principle, it is possible to start up and convey the prepared sliver into the vortex chamber of the air spinning device following the combing process, in which the output roller pair is decoupled from the at least one further pair of drafting rollers and/or apron rollers, which are stationary or only operated at an assigned holding speed. However, according to a further embodiment of the invention, the drafting system is stopped after combing and then started up for piecing. This embodiment of the invention ensures particularly reliably that the free sliver end is arranged in the vortex chamber in the desired manner at the start of the piecing process for connection to the free thread end.

Characteristic of the drafting system for conveying a fiber sliver in the direction of an inlet opening of a vortex chamber of an air spinning device, wherein the drafting system has a pair of output rollers that can be driven decoupled from the at least one further pair of drafting system rollers and/or apron rollers, is a control unit for carrying out the above-described method according to the invention or further developed for operating a drafting system after a spinning interruption. The control unit can be arranged directly at the spinning station or, according to an advantageous development of the invention, integrated into a central control unit for more than one spinning station or the air spinning machine. The central control unit can preferably be a mobile or stationary device outside the spinning station and/or air spinning machine. Particularly advantageously, the control unit or the monitoring unit is provided to variably adjust the combing speed and/or the holding speed so that optimal adaptation to the fibers is possible.

Fig. 1

in einer Vorderansicht eine Luftspinnmaschine mit Arbeitsstellen, die zur Versorgung ihrer Luftspinnvorrichtung jeweils eine arbeitsstelleneigene Fadenaufnahmeeinrichtung und eine Fadenvorbereitungseinrichtung aufweisen und

Fig. 2

in einer Schnittansicht in einer schematischen Darstellung eine Luftspinnvorrichtung während des Anspinnvorgangs.

An embodiment of the invention is explained below with reference to the drawings. In the drawings:

Fig.1

in a front view an air spinning machine with workstations, each of which has its own thread take-up device and a thread preparation device to supply its air spinning device and

Fig.2

in a sectional view in a schematic representation of an air spinning device during the piecing process.

The Fig.1 shows a schematic front view of a textile machine that produces winding packages, usually referred to as a cross-wound bobbin 9, in the present case an air-jet spinning machine 1. Such textile machines 1 have a plurality of spinning stations 2 between machine frames 13a, 13b arranged at the end of the machine. At each of the spinning stations 2, a spinning can 3 is positioned, which is equipped with a supply of feed material, for example with fiber sliver 25.

The spinning stations 2 also each have a drafting device 4, an air spinning device 5, a take-off device 6, a thread cleaner 7 and a thread traversing device 8, which ensures that the thread 36 spun or produced from the fiber band 25 in the air spinning device 5 is wound in crossing layers onto a winding bobbin 9. The so-called cross-wound bobbin 9 created during the spinning process is, as usual, held in a bobbin frame (not shown) and is rotated by a bobbin drive (also not shown).

Each of the spinning stations 2 is also equipped with a thread take-up device 39, which makes it possible to take up a thread end 37 of a finished thread 36 which has run onto the cross-wound bobbin 9 after an interruption in spinning and to transfer it to a so-called thread preparation device 40 arranged in the region of the take-off device 6.

The Fig.2 shows in side view and on a larger scale an air spinning device 5 suitable for carrying out the method according to a preferred embodiment during the piecing process.

As can be seen, the air spinning device 5 shown in section is preceded by the drafting device 4 for drawing the fiber sliver 25. In the fiber sliver running direction R behind the air spinning device 5 is a single-motor and reversibly driven take-off device 6 which ensures that the finished thread 36 can be transported in the direction of the take-up package 9 and in the opposite direction.

In the area of the thread take-off device 6, the thread preparation device 40 (not shown in detail here) is also arranged, which prepares the thread end 37 of the finished thread 36, retrieved by the thread take-up device 39, for the subsequent piecing process.

As in Fig.2 As shown, the air spinning device 5 essentially consists of a two-part outer housing 14, 15, an expansion housing 16, a nozzle block 17, a fiber band guide 18 and a hollow spinning cone 19.

The expansion housing 16, in conjunction with the front housing part 14 of the outer housing, forms a front annular space 20 which is connected to an overpressure source 22 via a pneumatic line 21 and is connected to the expansion space 28 arranged in the rear housing part 15 of the outer housing.

While the expansion space 28 is indirectly connected to the ambient atmosphere via an exhaust air duct 29, the annular space 20 is pneumatically continuously connected to at least one blown air nozzle 23, which are arranged in the nozzle block 17.

The blowing air nozzle 23 opens into a vortex chamber 33 in the area in front of the inlet opening 35 of the spinning cone 19 and is directed towards the head 24 of the spinning cone 19 in such a way that a rotating air flow is established thereon. The spinning cone 19 is preferably made of a highly wear-resistant material, for example a technical ceramic material.

To control the compressed air supply, the pneumatic line 21 is equipped with a valve 32, which is preferably actuated by a spinning station-specific control unit 38, which is connected to the valve via corresponding control lines.

During the normal, previously known spinning process (not shown here), the sliver 25 stored in a spinning can 3 first passes through the drafting system 4 on its way to the cross-wound bobbin 9, where it is strongly drawn. The drawn sliver 25 is then fed into the area of the inlet opening 27 via the output roller pair 26 of the drafting system 4. the air spinning device 5 and sucked into the vortex chamber 33 of the air spinning device 5 under the influence of a negative pressure flow there. Within the air spinning device 5, the stretched fiber band 25 passes via the fiber band guide 18 and the nozzle block 17 to the inlet opening 35 of the hollow spinning cone 19 and is drawn into the spinning cone 19 by the thread 36 forming within the spinning cone 19. The fiber band 25 is exposed in the area of the head 24 of the spinning cone 19 to the influence of a rotational flow which is generated by the air flow emerging from the nozzle block 17.

The valve 32 is opened for the defined supply of this air flow initiated by the overpressure source 22 to the nozzle block 17. In order to enable the air flow flowing in via the nozzle block 17 to flow out through the exhaust air duct 29 to the ambient atmosphere or to a machine-specific suction system during the spinning process, a valve 34 connected to the control unit 38 via a corresponding control line is opened.

During the spinning process, due to the continuous movement of the fiber sliver 25 in the fiber sliver running direction R, the fiber sliver 25 is continuously drawn into the hollow spinning cone 19, with the edge fibers being wound in a helical manner around the core fibers of the fiber sliver 25. The thread 36 produced in this way is drawn out of the air spinning device 5 by means of the thread take-off device 6 and then wound up into a cross-wound bobbin 9.

If spinning is interrupted during the spinning process, for example due to a break in the fiber sliver 25 or due to a controlled cut of the already spun thread 36 by the thread cleaner 7, a piecing process must first be carried out before the spinning process can be restarted.

As is known, in order to carry out a piecing process, on the one hand the stretched fiber band 25 and on the other hand the already finished thread 36 which has run onto the cross-wound bobbin 9 are required.

After a spinning interruption, the thread end 37 of the already finished thread 36 is first retrieved from the cross-wound bobbin 9 by the spinning station's own thread take-up device 39 of the affected spinning station 2 and fed into one of the air spinning devices 5 in The yarn is then transferred to the yarn preparation device 40 arranged downstream of the sliver running direction R. There, the yarn end 37 is largely freed of twist and loose fibers and then transferred to the vortex chamber 33 for piecing and positioned there.

To prepare the fiber sliver 25, the drafting system 4 is operated by the control unit in a combing mode during the return of the thread end 37 into the vortex chamber 33, in which the first drafting system roller pair 42, the second drafting system roller pair 43 and the apron roller pair 41 are stationary, whereas the output roller pair 26 is operated at a combing speed and thereby prepares the free end of the fiber sliver 25 in an optimal manner for the piecing process.

List of reference symbols

1 Air spinning machine 25 Sliver 2 Spinning station 26 Output roller pair 3 Spinning can 27 Entrance opening 4 Drafting system 28 Expansion space 5 Air spinning device 29 Exhaust duct 6 Extraction device 31 Holding/dissolving tube 7 Thread cleaner 32 Valve 8th Thread traversing device 33 Vortex chamber 9 Take-up spool 34 Valve 13a, 13b Machine frame 35 Entrance opening 14 Outer casing 36 thread 15 Outer casing 37 Thread end 16 Expansion housing 38 Control unit 17 Nozzle block 39 Thread take-up device 18 Sliver guide 40 Thread preparation device 19 Spinning cone 41 Pair of apron rollers 20 Annular space 42 first pair of drafting rollers 21 Pneumatic line 43 second pair of drafting rollers 22 Overpressure source 44 Thread guide channel 23 Blowing air nozzle R Sliver running direction 24 Head

Claims (6)

Method for operating a drafting system (4) having an output roller pair (26) and at least one further drafting system roller pair (42, 43) and/or apron roller pair (41), by means of which a fiber band (25) for producing a thread (36) is fed to a vortex chamber (33) of an air spinning device (5) of the spinning station (2) at a spinning station (2) of an air spinning machine (1), wherein the output roller pair (26) can be driven decoupled from the at least one further drafting system roller pair (42, 43) and/or apron roller pair (41),
characterized in that
the output roller pair (26) is driven at a predetermined combing speed for combing out the sliver end after a spinning interruption, and the at least one pair of drafting rollers (42, 43) and/or apron rollers (41) arranged upstream of the output roller pair (26) in the sliver running direction (R) is stopped or operated at a holding speed associated with the combing speed, which is a maximum of 10% of the combing speed. Method according to claim 1, characterized in that the output roller pair (26) is driven before the at least one further pair of drafting rollers (42, 43) and/or apron rollers (41) when the drafting system (4) is started up during piecing. Method according to claim 1 or 2, characterized in that the drafting system (4) is stopped after combing and is then started up for piecing. Drafting system for conveying a fiber sliver (25) in the direction of an inlet opening (35) of a vortex chamber (33) of an air spinning device (5), wherein the drafting system (4) has an output roller pair (26) which can be driven decoupled from at least one further drafting system roller pair (42, 43) and/or apron roller pair (41), characterized by
a control unit (38) for carrying out the method for operating a drafting system (4) after a spinning interruption according to one or more of claims 1 to 3. Drafting system according to claim 4, characterized in that the control unit (38) is integrated into a central control unit of the air spinning machine (1). Drafting system according to claim 4 or 5, characterized in that the control unit (38) is designed for variable adjustment of the combing speed and/or holding speed.

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