EP0303003B1 - Open-ended spinning apparatus and method for starting the same - Google Patents

Description

The present invention relates to an open-end spinning device with a spinning rotor and with a compressed air line for cleaning directed towards the inner surface of the spinning rotor, which is connected to a compressed air source via a shut-off valve, and a method for starting up such a device.

It is known to supply compressed air to the rotor of an open-end spinning device in order to clean it of deposits and fibers (DE-A 2,505,943). The contaminants and fibers released by the compressed air jet are removed by suction air. Before the actual re-piecing process, the sliver feed is switched on and off again in order to remove the unsuitable fibers for the piecing process. In this way, a fiber beard should always be of the same quality and quantity for spinning. To ensure that these fibers, which are temporarily fed into the rotor, are safely removed from the spinning rotor again, the excess pressure is maintained beyond this pre-feeding until the previously braked spinning rotor is released. This cleaning overpressure in the rotor impairs the flow conditions through the fiber feed channel to the fiber beard, so that there is a risk that the fibers are prevented from entering the spinning rotor during the pre-feeding. After the fiber feeding device has been stopped, the excess pressure continues to have an effect on the fiber beard and thereby causes undefined fiber beard ratios. This leads to malfunctions in the piecing process.

The object of the present invention is therefore to improve the known device and the known method in such a way that on the one hand thorough cleaning of the spinning rotor with a safe removal of the fibers and impurities in the spinning rotor is achieved and on the other hand a fiber beard can always be obtained of the same nature.

This object is achieved according to the invention by a pressure control device which can be preset to at least two overpressures, one or the other overpressure being able to be supplied to the shut-off valve depending on the execution of the piecing process. In this way it is possible, after a yarn break, to supply the spinning rotor with a compressed air stream which is at a high overpressure and which detaches the fibers which have meanwhile accumulated in the spinning rotor from the collecting groove, so that they are removed by the action of the suction air stream which produces the spinning vacuum. A fiber ring formed by the fibers must be broken open. Depending on where the thread break has occurred between the collecting groove and take-off rollers, a more or less long thread section enters the collecting groove when the thread breaks, which also has to be removed from it. During the supply of the compressed air flow under high pressure, the spinning rotor does not stand still, but runs down, so that the centrifugal force acting on the material to be removed decreases over time, but the compressed air can nevertheless be supplied to any point on the circumference of the collecting groove. Once the spinning rotor has been cleaned, a fiber beard of the same quality should always be produced for the piecing. This is done either by a temporary advance with a fixed time interval from the onset of the fiber feed required for the spinning process or by a pre-activation of the fiber feed, whereby the fibers are initially prevented from entering the spinning rotor until they are ready for piecing, ie for the start of the spinning process, are required in the spinning rotor. During the period up to the start of fiber feeding in the Spinning the rotor should not get fibers into the spinning rotor after the pre-feeding has been switched off or after the fiber feed has been switched on, on the other hand it should be prevented that the fibers in the opening roller housing can leave this housing at another location, e.g. in the area of the feeding device or at a dirt separating opening. For this reason, a stream of compressed air at low pressure is supplied to the spinning rotor during the time after the rotor cleaning has ended. The device according to the invention thus fulfills a double function. On the one hand, it is used for cleaning the spinning rotor. In addition, it also fulfills the task of improving piecing.

The pressure control device can be controlled in various ways in order to supply compressed air at the desired height to the individual spinning station at the desired time. According to an advantageous embodiment, a pressure sensor that scans the pressure between the pressure control device and the shut-off valve can be provided, which is connected to the pressure control device via a time delay device. Such a pressure sensor senses the pressure in the compressed air line and responds to a pressure drop that occurs automatically when a shut-off valve is opened, and controls the pressure control device via the time delay device.

The pressure control device can be designed differently and e.g. have a pressure reducing valve that can be switched in two stages. The amount of compressed air can be controlled particularly precisely with the aid of a pressure control device which has parallel lines, one line of which receives a pressure reducing device. With the help of this pressure reducing device, the low overpressure is determined.

In order to be able to control the pressure control device in a simple manner, regardless of its special design, a switching device is preferably assigned to the spinning device or a switching device can be assigned to it which is controlled by the control device Pressure control device communicates. Such a switching device can, for example, be provided separately for each spinning station or can be arranged on an operating device which can be moved to the individual spinning station and thereby assigns a switching device to the relevant spinning device.

As a rule, many similar open-end spinning devices are arranged next to one another in the machine nowadays. In this case, according to the invention, the shut-off valves of this plurality of similar open-end spinning devices are connected on the input side to the parallel lines of the pressure control device, the pressure reducing device of which can be connected upstream of the shut-off valve by means of a switching device. In this way, the overpressure required in each case can be controlled in a simple manner from each open-end spinning device.

According to a simple design of the device according to the invention, which is particularly suitable for manually operated open-end spinning devices, the switching devices are designed as changeover valves, by means of which the shut-off valves of the individual open-end spinning devices can optionally be connected to one or the other of the two parallel lines.

In order to achieve the simplest possible design of the device according to the invention in a large number of similar open-end spinning devices, it is preferably provided that the shut-off valves are connected to the pressure control device via a common main line. In order to select the desired overpressure in each case, a switchover device that can be controlled by the switching devices assigned or assignable to the individual open-end spinning devices can be provided between the parallel lines of the pressure control device and the main line.

Instead of a switching device or in addition to this, it can be provided in a further embodiment of the subject matter of the invention that the line arranged parallel to the line with the pressure reducing device has a shut-off valve for shutting off or releasing the high excess pressure.

A shut-off valve or a separate shut-off valve for shutting off or releasing the low overpressure is advantageously provided between the pressure reducing device and the main line. In this way it is possible to completely switch off the compressed air supply to the main line if this is desired for any reason. So that a valve of low power can then be used for the shutoff valve downstream of the pressure reducing device, a check valve protecting this shutoff valve is expediently provided between the main line and the shutoff valve for shutting off or releasing the low excess pressure.

According to a preferred embodiment of the subject matter of the invention, the pressure control device is in a control connection with a piecing device which can be moved along the open-end spinning devices and which has an actuating element which can be delivered to the shut-off valves and / or switching devices of the individual open-end spinning devices. As a result, the overpressure can be selected from the piecing device at the desired level, while on the other hand the compressed air supply to the spinning rotor is released or prevented at the individual open-end spinning device from the movable piecing device.

If a plurality of movable piecing devices are provided, the case may arise that a high overpressure is required for the piecing process which is controlled from one piecing device, while a low overpressure is required for another piecing process which is controlled by a further piecing device . Since different high pressures cannot be introduced into the common main line at the same time, it can be provided that the piecing devices are coupled via a common control device so that the actuating element of only one of the piecing devices is effective in each case. Alternatively, however, it can also be provided that a separate main line is assigned to each movable piecing device.

In order to be able to individually apply a high or a low overpressure to each main line if several separate main lines are provided, it is expediently provided in an advantageous embodiment of the subject matter of the invention that each main line has two parallel lines on the inlet side, one of which includes the line Pressure reducing device is assigned to all main lines together, while the other line has a separate shut-off valve for each main line.

With the aid of the device according to the invention, piecing can be carried out in various ways. A method is particularly advantageous in which the compressed air is fed into the spinning rotor at high pressure during the preparation of piecing to clean the spinning rotor and then, but before the fiber feed into the spinning rotor, is reduced to a lower value and finally before the return delivery the thread in the spinning rotor is switched off. In this way, on the one hand, intensive cleaning of the spinning rotor is achieved, while, on the other hand, it is ensured that the fibers can be easily removed again before the actual piecing process.

In practice, the aim is to keep the downtime of the spinning device as short as possible. For this reason, the time for switching from the high to the low overpressure value is not fixed, but is advantageously chosen as a function of the runout behavior of the spinning rotor to be stopped. While a long run-down time for the spinning rotor has to be taken into account in spinning rotors with a large mass and thus the switchover of the high overpressure to the low overpressure can only take place at a relatively late point in time, a spinning rotor with a low mass reaches its standstill significantly earlier, so that correspondingly earlier switching of the high to the low overpressure time is gained.

The amount of overpressure in the run-out phase of the spinning rotor and in the subsequent phase during which the fiber feed is released can easily be determined on the basis of experiments, but it has been shown that it is advantageous if the low value of the overpressure is between 10% and 40% of the high value of the overpressure.

The cleaning effect can be intensified by switching the spinning rotor one or more times from high to low overpressure and back during the runout.

According to a preferred method, the fibers fed to the open-end spinning device after the rotor has come to a standstill are fed into the spinning rotor, the fiber feeding into the spinning rotor being interrupted at a predetermined interval before piecing and the compressed air being supplied to the spinning rotor during the entire duration of the fiber feeding is held low. By temporarily switching on the fiber feed, the period between the renewed stopping of the fiber feed and the start of the piecing process can be precisely defined, so that the fiber beard also has a defined state at the piecing time. The overpressure of the compressed air introduced into the spinning rotor during the fiber feed has only a relatively low value and may even reach zero if the geometry of the spinning rotor and the suction acting in the spinning rotor ensure that the fibers are present during the temporary fiber feeding can also be safely removed from the spinning rotor.

The low value for the compressed air is expediently maintained even after the temporary fiber feed into the spinning rotor has ended until the start of the spinning rotor. In this way it is ensured that fibers which are still in the clothing of the opening roller after the fiber feed has been switched off and therefore also get into the spinning rotor after the temporary fiber supply has ended, are immediately safely removed therefrom.

So that the high overpressure is immediately available when a piecing process becomes necessary, for example due to a broken thread, and the spinning rotor can thus be stopped immediately, it is advantageous if, after interrupting the compressed air supply into the spinning rotor, the high overpressure is already provided again during the piecing process, without that he, however, in the spinning rotor reached. This eliminates the loss of time that would otherwise be required to rebuild the high overpressure. This is advantageous if the piecing process is monitored and, if the latter fails, the preparation of a new piecing process is initiated immediately.

The invention allows in a simple manner that on the one hand the spinning rotor is cleaned effectively and in this way guarantees good thread quality in the long run. On the other hand, the invention prevents fibers from being able to settle in the spinning rotor at an undesired point in time, so that the spinning rotor is certainly kept free of fibers before the piecing process. In this way, the amount of fibers deposited for spinning in the spinning rotor can be precisely determined, so that defined piecing results. The invention thus contributes in the same way to a quality improvement of the piecing as well as the thread subsequently spun. The device required for this is simple and also takes up little space. In addition, it is cost-saving due to lower air consumption. Since it must be installed at the beginning of a main line in an advantageous embodiment of the subject matter of the invention, this device can be easily and inexpensively retrofitted into any existing machine.

Fig. 1

in einer Zeittafel die für das Vorbereiten eines Anspinnvorganges und für das Anspinnen selber erforderlichen Schalt-und Arbeitsvorgänge;

Fig. 2

im Schema eine erste Ausbildung der erfindungsgemäßen Vorrichtung;

Fig. 3

im Querschnitt eine Spinnvorrichtung, die für die Durchführung des erfindungsgemäßen Verfahrens geeignet ist;

Fig. 4

im Schema eine Abwandlung der in Fig. 2 gezeigten Vorrichtung, bei welcher für eine Vielzahl von Spinnvorrichtungen nur eine einzige Hauptleitung vorgesehen ist;

Fig. 5

im Schema eine Abwandlung der in Fig. 4 gezeigten Vorrichtung, bei welcher die jeweilige Höhe des Überdruckes mit Hilfe von längs den Spinnvorrichtungen verfahrbaren Anspinnvorrichtungen ausgewählt wird;

Fig. 6

im Schema eine weitere Abwandlung des Erfindungsgegenstandes, bei welcher die Steuerung von einer verfahrbaren Anspinnvorrichtung aus erfolgt;

Fig. 7

im Schema noch eine andere Abwandlung der erfindungsgemäßen Vorrichtung, bei welcher die Steuerung der Drucksteuervorrichtung in Abhängigkeit von einem Druckabfall in der Druckluftleitung erfolgt; und

The invention is explained in more detail below on the basis of several exemplary embodiments. Show it:

Fig. 1

in a time table the switching and work processes required for the preparation of a piecing process and for the piecing itself;

Fig. 2

in the diagram a first embodiment of the device according to the invention;

Fig. 3

in cross section a spinning device which is suitable for performing the method according to the invention;

Fig. 4

in the diagram a modification of the device shown in Figure 2, in which only a single main line is provided for a plurality of spinning devices;

Fig. 5

in the diagram a modification of the device shown in FIG. 4, in which the respective height of the excess pressure is selected with the aid of piecing devices which can be moved along the spinning devices;

Fig. 6

in the diagram, a further modification of the subject matter of the invention, in which the control is carried out from a movable piecing device;

Fig. 7

in the scheme yet another modification of the device according to the invention, in which the control of the pressure control device takes place as a function of a pressure drop in the compressed air line; and

First, the most important parts of an open-end spinning device are explained with reference to FIG. 3, which shows the spinning position of a rotor spinning machine in section. Each such spinning station has a spinning rotor 1, to which a fiber sliver 9, which is broken down into fibers 90, is fed and from which the fiber material is drawn off again in the form of a spun thread 91.

The spinning rotor 1 is arranged in a known manner in a housing 10, which is only indicated in FIG. 3 and is connected via a suction line 100 to a vacuum source, not shown. The housing 10 is covered by a cover 101, which in turn is supported by a cover 102 which covers all elements of the spinning device of a spinning station. In the cover 101 there is a thread draw-off tube 103, through which the thread 91 is drawn off with the aid of draw-off rollers (FIG. 9: roller 193, roller 192), in order then to be fed to a winding device, also not shown, for winding up. The thread 91 passes through a thread monitor 11, the sensor 110 of which monitors the thread 91 for the presence or absence of the thread tension under the pretension of a compression spring 111.

In the cover 101 there is also a part 120 of a fiber feed channel 12, the other part 121 of which is arranged in a stationary manner and in the position of the cover 102 shown is in alignment with part 120 of the fiber feed channel 12. The fiber feed channel 12 is based on an opening roller housing 13, which is only indicated schematically, in which a rotating opening roller 130 is arranged in a known manner.

The opening roller 130 is preceded by a feed device 14 which, in the embodiment shown, consists of a feed roller 140 and a feed trough 141 which cooperates elastically with it. The feed trough 141 is pivotally mounted on an axis 143, which also pivotally carries a clamping lever 144 which cooperates with the feed trough 141. The clamping lever 144 can be brought into abutment against the feed trough 141 with an end designed as a clamping piece 145 and thereby swivel the feed trough 141 acted upon by a compression spring 142 away from the feed roller 140 and thereby clamp the sliver 9 between itself and the feed trough 141. The clamping lever 144 has a guide funnel 146 for the sliver 9 between its clamping piece 145 and the pivot axis 143.

At its end 147 facing away from the clamping piece 145, the clamping lever 144 is connected to the armature 150 of an electromagnet 15. The armature 150 has a driving ring 151 for driving the clamping lever 144 at its end facing away from the electromagnet 15. Between the electromagnet 15 and the clamping lever 144 there is a compression spring 152 which, when the electromagnet 15 drops, pivots the clamping lever 144 with its clamping piece 145 against the fiber sliver 9.

A switch button 148 is located on the cover 102, with the aid of which the thread monitor 11 is bridged and the electromagnet 15 can be addressed independently of the current position of the sensor 110 of the thread monitor 11.

In the cover 101 there is also a compressed air line 2, which is directed with one or more orifices 20 onto the inner surface of the spinning rotor 1. In the compressed air line 2 there is a shut-off valve 21 which is carried by the cover 102 and can be actuated by a control lever 3.

The control lever 3 sits together with the cover 102 on a common pivot axis 104 and is acted upon in a direction which will be described later in the direction out of the cover 102. In the longitudinal direction of the control lever 3, ie according to FIG. 3 in the vertical direction, a switch button 30 is slidably mounted on the cover 102, which is acted upon in the direction of the control lever 3 by a compression spring 31 supported on the cover 102. The control lever 3 has at its end facing the switch button 30 a recess 32, in which the switch button 30 can engage with a detent 300. The latching lug 300 has a run-up slope 301 on its side facing the operating side (in FIG. 3 on the right) so that the control lever 3 can be brought into the position shown in FIG. 3 even without the control button 30 being raised in a controlled manner.

In the vicinity of its pivot axis 104, the control lever 3 has a control cam 33 with which a roller 340 cooperates, which is arranged at the end of a two-armed intermediate lever 34. The free end 341 of the intermediate lever 34 is connected to a pull rod 35 which carries at its end remote from the intermediate lever 34 a brake 350 which, by the action of the control cam 33 against the action of a tension spring 351 at a distance from a shaft carrying the spinning rotor 1 16 is held.

Fig. 2 shows schematically a part of a double-sided open-end spinning device, from the machine side I a plurality of similar spinning positions A, B, C ... and from the machine side II a plurality of similar spinning positions A ', B', C '... are shown.

As shown in the example of the spinning station A, each compressed air line 2 is connected via the shut-off valve 21 (see FIG. 3) to a pressure control device 4, which in turn is connected to a compressed air source 40. In this way, the shut-off valves 21 of the various spinning positions A, B, C ... and A ', B', C '.... upstream pressure control device 4 contains A, B, C ... and A', B per spinning position ', C' ... a changeover valve 22, the output side of which is connected to the inlet side of an associated shut-off valve 21. Each changeover valve 22 is connected to a line 5 via a connecting line 50 and to a line 6 via a connecting line 60. The line 5 is used to supply compressed air at a relatively high pressure, while the line 6 is used to supply compressed air at a lower pressure. With the lines 5 and 6 are also the switching valves 22 of the other spinning positions B, C ... and A ', B', C '... in connection.

The pressure control device 4 also has, in a first line section 41 which is connected to the compressed air source 40, a pressure reducing valve 42 which acts on the high line 5 Overpressure. At the outlet of this pressure reducing valve 42, the line section 41 is divided into the two parallel lines 5 and 6 mentioned, the line 6 having a pressure reducing device 43 which, according to FIG. 2, is also designed as a pressure reducing valve. This pressure reducing device 43 determines the low pressure for the line 6.

In the open-end spinning machine shown in Fig. 2, the shut-off valves 21 of the various spinning positions A, B, C ... and A ', B', C '... each have a changeover valve 22 on the input side with the parallel lines 5 and 6 the pressure control device 4 in connection. The switching valves 22 form switching devices 7, with the help of which line 5 or line 6 of the pressure control device 4 of each spinning station A, B, C ... and A ', B', C '... can be connected upstream.

Now that the construction of the device has been described, the piecing process will be explained below with reference to FIG. 1. 1 shows the rotor speed n _R , the compressed air supply P _R in the spinning rotor 1, the compressed air supply P _L in the compressed air line 2 upstream of the shut-off valve 21, the fiber feed Q _F and the movement V _G in the return or take-off direction . The time t is plotted horizontally. F _B indicates the occurrence of a thread break. V _A denotes the preparation of the piecing S _A , V _F the preparation of a defined fiber beard, R _R the rotor cleaning and F _A the period during which it can be queried whether the piecing process has been successful or failed. Further details are explained below in connection with the functional description.

As shown in FIG. 3, the sensor 110 of the thread monitor 1 is held in its pivot position against the action of the compression spring 111 during the normal spinning process by the thread tension. If a thread break F _B now occurs, the thread 91 releases the sensor 110, which now is brought into its end position by the compression spring 111. The thread monitor 11 causes the fiber supply Q _{F to be} stopped immediately by actuating the electromagnet 15. In a known manner, the clamping lever 144 is brought with its clamping piece 145 into contact with the sliver 9 and the feed trough 141 is pivoted away from the feed roller 140.

When the thread break F _{B occurs} , the thread monitor 11 also brings the thread 91 to a standstill by stopping the winding device (not shown).

Through the thread break F _B , the thread monitor 11 also triggers a signal which indicates that a piecing process must have been carried out at this spinning position, for example the spinning position A. The display takes place, for example, with the aid of a signal lamp (not shown) provided per spinning station A, B, C ... or A ', B', C '... The operator now goes to this spinning station A and moves the switch button 30 against the action of the compression spring 31, so that the catch 300 releases the control lever 3, which now moves out of the cover 102 due to the action of the tension spring 351 (according to FIG. 3) right) is pivoted. The roller 340 runs along the control cam 33, so that the pull rod 35 can now follow the tension exerted by the tension spring 351 and brings the brake 350 into contact with the shaft 16. As a result, the spinning rotor 1 is braked to a standstill (see rotor speed n _R in FIG. 1).

As shown in FIG. 1, compressed air under high pressure had previously been provided by a corresponding switching position of the changeover valve 22 in the compressed air line 2 (before the shut-off valve 21). By releasing the control lever 3 and pivoting it out of the cover 102, the control lever 3 releases the switching bolt 210 of the shut-off valve 21, so that the compressed air under high pressure now reaches the spinning rotor 1 (see compressed air P _RH ). This compressed air P _RH blows up the spinning rotor 1, which is still rotating located fiber ring 92. When the spinning rotor 1 runs out, the centrifugal force is finally so low that the suction air effective in the suction line 100 is able to remove the fiber ring 92 which has been blown open and the fibers 90 which were still supplied by the opening roller 130 and which were still in the clothing, from the spinning rotor 1 and vacuum the housing 10. As the curve for the rotor speed n _R shows, the spinning rotor 1 takes a different amount of time to stop, which depends on the mass of the spinning rotor 1. Accordingly, the compressed air supply P _R must also be of different lengths under high pressure (see P _RH ), which is why the time for switching from high to low overpressure is selected as a function of the runout behavior of spinning rotor 1, as shown in FIG. 1, in order not to be useless Wasting time.

After the spinning rotor 1 is stopped, the compressed air supply P _{R is switched} to an overpressure (see compressed air P _RN ), which is done by actuating a drive element 220 of the changeover valve 22. Compressed air with a lower excess pressure now enters the spinning rotor 1 through the shut-off valve 21 which is still open. After this changeover of the changeover valve 22, the electromagnet 15 is now actuated via the switch button 148 in such a way that it engages the clamping lever 144 with its clamping piece 145 from the feed trough 141 swings away and thus releases the sliver 9 again. As a result of the feed trough 141 again approaching the feed roller 140, the fiber sliver 9 is in turn fed to the opening roller 130 and dissolved by the latter to fibers 90 which are fed into the interior of the spinning rotor 1. Due to the overpressure acting in the compressed air line 2, the fibers 90 are whirled up immediately and prevented from being deposited in the spinning rotor 1, which is still stationary. The fibers 90 are immediately sucked out of the spinning rotor 1 and removed by the negative pressure acting in the suction line 100. This feeding of fibers 90 into the spinning rotor 1 removes the part of the fiber sliver 9 which has become unusable after the thread break F _B has occurred.

After a time sufficient to remove the unusable part of the sliver 90, the fiber feed Q _{F is} switched off again by releasing the switch button 148 for the electromagnet 15, so that by clamping the sliver 9 and pivoting away the feed trough 141 from the feed roller 140 the fiber delivery to the opening roller 130 is interrupted again.

After the feeding device 14 has stopped, but before the start of piecing S _A , the compressed air supply P _R in the spinning rotor 1 is switched off again (see compressed air P _RO ). For this purpose, the control lever 3 is raised again in the device shown in FIG. 3 and pressed into the cover 102. Here, the control lever 3 actuates the switching pin 210 and thus interrupts the supply of compressed air to the spinning rotor 1. The control lever 3 runs with its upper end against the run-up slope 301 of the switching button 30 and lifts it briefly until the detent 300 in the recess 32 of the Control lever 3 engages and fixes it in the position shown.

When the control lever 3 swings back into the basic position shown, the brake 350 also releases the shaft 16 of the spinning rotor 1, which now runs up to its operating speed (see rotor speed n _R ).

The actual piecing is carried out in coordination with this rotor run-up. The piecing process is also coordinated in such a way to the point in time at which the temporary fiber feed Q _F in the spinning rotor 1 is interrupted that from the interruption of the temporary fiber feed Q _F in the spinning rotor 1 until the fiber feed Q _F in the spinning rotor is switched on again t _F passes. This ensures that the sliver is in a defined state at the moment of attachment.

Shortly after returning the control lever 3 to the basic position shown in FIG. 3, the changeover valve 22 is switched over according to FIG. 1, so that compressed air which is under high pressure is again provided in the part of the compressed air line 2 located in front of the shutoff valve 21.

The thread 91 is returned to the spinning rotor 1 in coordination with the re-release of the fiber feed Q _F and, after a short dwell time, is again drawn out of the spinning rotor 1 (see thread movement V _G ).

After the piecing process has ended, a check is carried out during the period F _A to determine whether piecing has been successful. If this is the case, spinning station A continues to run at production speed. Otherwise, piecing S _{A is} repeated, which is indicated by dashed lines in the individual curves. Since the compressed air with a high value (see compressed air P _LH ) is already provided by the previous switching of the changeover valve 22 (see compressed air supply P _L ), the preparation phase V _A for the next piecing process can be initiated immediately.

Since the transition from high to low overpressure in the spinning rotor 1 (see compressed air P _RH and P _RN ) depends solely on the overpressure provided (see P _LH and P _LN ), this transition falls in time with the compressed air supply P _R and the compressed air supply P _L together.

1 shows that compressed air is fed into the spinning rotor 1 during the entire preparation phase S _A for piecing, including the rotor cleaning phase R _R. During the rotor cleaning R _R until the rotor has come to a standstill, the compressed air is passed into the spinning rotor 1 at a high excess pressure, for example 6 bar. As a result, the fiber ring 92 is blown open and, together with individual fibers 90, sucked out of the spinning rotor 1. For the later one Temporary fiber feeding Q _F , the compressed air is then reduced to a low value, for example 1 to 2 bar. The overpressure is dimensioned such that on the one hand the fibers 90 reach the fiber feed channel 12 unhindered from the opening roller housing 13, but on the other hand are prevented from being deposited in the stationary spinning rotor 1. This ensures that no fibers 90 several times to run around the opening roller 130 and optionally in the region of the feed device 14 or elsewhere get stuck in the opening cylinder housing 13 and can thus prevent them in re-release of the fiber feeding Q _F during piecing S _A together with the opening roller 130 newly introduced fibers 90 get into the spinning rotor 1 and thus question the success of the piecing.

If a dirt separating opening 17 is provided in the opening roller housing 13 between the feed device 14 and the fiber feed channel 12, the overpressure is dimensioned in this way so that it has no adverse effects on the inside of the opening roller housing 13, so that no fibers 90 make up the opening roller housing 13 leave through the dirt separating opening 17.

It has been shown that the low value P _{RN of} the overpressure of the compressed air flow directed into the spinning rotor 1 need only be 10% to 40% compared to the overpressure (P _RH ) required for the rotor cleaning R _R. The level of the low overpressure (P _RN ) depends on various factors such as the speed of the opening roller 130, the level of the underpressure in the suction line 100, the geometry of the housing 10 and the spinning rotor 1, etc.

As the times t _F and t _{F '} in FIG. 1 show, the release of the fiber feed Q _F can take place at different times compared to the run-up of the rotor speed n _R , but then the time t _{F' is also} a fixed time. To prevent t _F or t _{F '} between switching off the interim during this specified time Fiber feed Q _F during the preparation V _{A of} the piecing process and the renewed switching on of the fiber feed Q _F during piecing S _A unwanted fibers 90 settle in the spinning rotor 1, the overpressure with low value (P _RN ) becomes at least during the period of the intermediate fiber feed Q _F maintain. It is advantageous if this compressed air supply with a slight excess pressure is maintained even after this temporary fiber feed Q _{F has ended} until the start of the spinning rotor 1 again. Under certain circumstances, however, the compressed air supply P _R can also be interrupted before the spinning rotor 1 restarts, if, depending on the respective conditions, it must not be expected that fibers 90 or an unacceptable number of fibers 90 will get into the spinning rotor 1. The thread return or the reinsertion of the thread take-off (see thread movement V _G ) and the dwell time of the thread 91 in the spinning rotor 1 can also vary depending on the material, rotor speed n _R etc.

The described method ensures a uniform fiber transport from the feed device 14 into the spinning rotor 1 and a controlled insertion of the fiber feed Q _F for the piecing S _A. Nevertheless, failure of the piecing process cannot always be ruled out, for example due to dirt components that get into the spinning rotor 1 during the piecing phase. The piecing S _A is therefore monitored. To this end, it may be sufficient to monitor the thread 91 for its absence or presence. However, it can also be provided that the piecing in thread 91 is checked for its quality and for deviations from predetermined target values. If the piecing is to be regarded as unsuccessful, the preparation V _{A of} a new piecing process is initiated immediately by controlling the thread monitor 11 or a further thread monitor, not shown, as shown in FIG. 1. In order not to waste any time, the overpressure is applied to the spinning rotor 1 immediately after the compressed air supply P _{R has} ended, ie already switched during the piecing S _A from its low value P _LN to its high value P _LH . Since the compressed air supply P _R in the spinning rotor 1 has already been interrupted at this point in time by actuating the shut-off valve 21, the high excess pressure is only provided in this way, but does not get into the spinning rotor 1.

The compressed air supply P _L can be controlled in different ways depending on the design of the changeover valve 22. If the drive element 220 is designed, for example, as an electromagnet, a switching element can be provided on the winding device, for example, with the aid of which this drive element 220 can be controlled. This is particularly advantageous since, in the case of manually operated spinning devices, the operator must first raise the bobbin and lower it again later.

FIG. 2 shows an element designed as a pressure reducing valve (see pressure reducing valve 42 or pressure reducing device 43) for determining the high and low overpressures (P _LH , P _LN ). It is of course also possible to determine the desired pressure in a different manner, for example with the aid of overflow valves, in which case the desired overpressure can then be taken from the pipeline or the line upstream of this overflow valve.

As a comparison of FIGS. 2 and 4 shows, the element for setting the low overpressure can be arranged in series with the element (FIG. 2) which sets the high overpressure (P _LH ), or the two elements for that Setting the high and low overpressure (42, 43) can also be arranged parallel to each other (Fig. 4).

Fig. 2 shows a device in which at each individual spinning station A, B, C ... or A ', B', C '... a separate switch valve 22 is provided. This is particularly advantageous for test devices with only a single or a few spinning stations. However, it is not necessary to provide such a changeover valve 22 separately at each spinning station. As shown in FIG. 4, it is sufficient if a changeover valve 23 is provided once for the entire machine. This changeover valve 23 has an electromagnetic drive 230, which can be controlled from each spinning station A, B, C, D ... or A ', B', C ', D' ...

With the output side of the switching valve 23 is a main line 24 in connection, from which the compressed air lines 2 with the shut-off valves 21 of the individual spinning positions A, B, C, D .. and A ', B', C ', D' ... branch off . The shut-off valves 21 are thus connected to the parallel lines 5 and 6 of the pressure control device 4 via a common main line 24, which begins at the outlet of the changeover valve 23.

The two lines 5 and 6 for the high and for the low overpressure are connected to the two input sides of the changeover valve 23, the line 6 containing a pressure reducing device 43 in the manner described above. 4, the pressure reducing valve 42 or another suitable device for determining the excess pressure in the line 5 and not in a line section 41 connected upstream of the two lines 5 and 6 is arranged according to FIG. 4.

For the control of the electromagnet 230 and thus the changeover valve 23, each spinning station A, B, C, D ... and A ', B', C ', D' ... is assigned a switching device 7 without it being necessary that such a switching device 7 is provided separately for each spinning station A, B, C, D ... and A ', B', C ', D' ... It is sufficient if such switching devices 7 are arranged so that for the the desired overpressure can be made available to corresponding spinning stations. Such a switching device 7 can either be assigned to each spinning station A, B, C, D ... or A ', B', C ', D' or two or more spinning stations together.

4 shows various options for controlling the changeover valve 23.

On the machine side I, two spinning positions A and B, C and D ... together are assigned a switching device 7 designed as a changeover switch 36, which in one end position acts on the electromagnet 230 so that the changeover valve 23 supplies the main line 24 with high pressure standing compressed air (P _LH ), and in the other end position acts on the changeover valve 230 in such a way that the changeover valve 23 supplies the main line 24 with less compressed air (P _LN ).

For the spinning positions A ', B', C ', D' ... the machine side II, a separate switch 360 or 361 is provided as the switching device 7 for the application of the main line 24 with high or low overpressure.

The above description shows that both the method and the device can be modified in various ways, which can be done in particular by replacing individual features with equivalents or through other combinations. If the device has also been described on the basis of a very specific exemplary embodiment (FIG. 3), other elements can also be used to control the compressed air flow and for the speed of the spinning rotor 1. In particular, this does not require a control lever 3 that can be moved relative to the cover 102. The shut-off valve 21 can, if desired, also be operated directly. Likewise, instead of a mechanical control of the brake 230 for the spinning rotor 1, an electrically controlled brake can also be used.

Another exemplary embodiment is described below with reference to FIG. 5. While the devices described with the aid of FIGS. 2 and 4 are specifically intended for manual control of the piecing process, FIG. 5 shows that this device is also suitable for automatic control. For each machine side I and II, a piecing device 37 which is movable along a machine side I or II is provided with a piecing control device 370 for controlling the piecing process. This piecing control device 370 is connected in a suitable manner via an actuating element, for example via a control pin or the like (see operative connection 371), to the switching pin 210 if the piecing device 37 is used to carry out a piecing process at a spinning station A, B, C, D, E, F ... or A ′, B ′, C ′, D ′, E ′, F ′ ... stopped. After the piecing process has ended, this operative connection 371 is released again.

This operative connection 371 can have, for example, a lever as the actuating element, which lifts the switch button 30 to release the control lever 3, as well as a bolt to later return the control lever 3 to its basic position. The shut-off valve 21 is then actuated in the manner already described. As an actuating element, however, a device can also be provided, which is mechanically, electrically or in another way, e.g. non-contact, the shut-off valve 21 controls, possibly also with the interposition of a computer provided at one end of the machine.

The pressure control device 4 shown in FIG. 4 can be used to provide compressed air P _L in the main line 24, the electromagnet 230 then being able to be controlled in front of the movable piecing device 37. In this case, the piecing device 37 thus replaces the changeover switch 36 or the switches 360 and 361 of FIG. 4 and itself forms the switching device 7, being one certain spinning station A, B, C, D, E, F ... or A ', B', C ', D', E ', F' ... is assigned by performing the maintenance of this spinning station and cooperates with this mechanically and / or electrically.

Fig. 5 shows a modified pressure control device 4, in which a shut-off valve 51 is provided in line 5 for shutting off or releasing the high excess pressure (P _LH ), while in turn a pressure-reducing device 43 is provided in parallel line 6. According to the exemplary embodiment shown in FIG. 5, this pressure reducing device 43 remains in constant connection with the main line 24, while the shut-off valve 51 in the line 5 controls the connection of the main line 24 with the line section 41. The shut-off valve 51 is controlled by means of an electromagnet 510, which in turn is connected to the piecing devices 37 on the two machine sides I and II. In order to prevent the piecing devices 37 from being able to send different control commands to the electromagnet 510, a control device 52 is interposed between the piecing devices 37 on the one hand and the electromagnet 510 on the other hand, which functionally couples the two piecing devices 37 to one another. This control device 52 synchronizes the two piecing devices 37 in such a way that in each case the actuating element only one of the two spinning devices 37 is effective and these piecing devices 37 carry out their piecing processes at different times from one another in such a way that the desired compressed air supply P _R to the spinning rotors I to be serviced is in agreement with the piecing process is delayed.

The shut-off valve 51 releases the high overpressure P _LH at the desired time, the always released lower overpressure P _LN from line 6 having no effect on the main line 24. If, on the other hand, the shut-off valve 51 is switched off, only the lower overpressure P _LN effective in the line 6 acts.

Fig. 6 shows a further modification for controlling the overpressure of the spinning rotor 1 during the preparation V _A for piecing S _A and during the piecing S _A itself. The pressure control device 4 in turn has two lines 5 and 6, with a pressure reducing valve 42 or another pressure reducing device and then a shut-off valve 51 being arranged in the line 5. The shut-off valve 51 is in turn under the control of the piecing device 37.

In line 6 there is a pressure reducing device 43, which is also designed, for example, as a pressure reducing valve, and a shut-off valve 61 and a check valve 62 are arranged thereon. The shut-off valve is under the control of an electromagnet 610, which is also connected to the piecing device 37. The electromagnets 510 and 610 are coupled via the piecing control device 370 of the piecing device 37 in such a way that the shut-off valve 51 for the high pressure or the shut-off valve 61 for the low pressure alternately enables the flow of the compressed air. The check valve 62 arranged between the main line 24 and the shut-off valve 61 protects the shut-off valve 61, but need not necessarily be provided. However, it has the advantage that a small dimensioning can be provided for the shut-off valve 61, since the high pressure P _LH applied to the main line 24 is decoupled from the shut-off valve 61 by the check valve 62.

If not only a single movable piecing device 37 is provided for the two machine sides, which serves both the machine side I and the machine side II, but instead a separate piecing device 37 is provided for each machine side I and II, a control device 52 according to FIG 5 are provided in order to achieve safe and trouble-free control of the overpressure P _L in the main line 24, which in this case is in turn assigned to both machine sides I and II.

FIG. 6 shows another possibility for controlling the overpressure if separate piecing devices 37 are provided for the two machine sides I and II. In order to be able to operate both sides completely independently of one another, a separate main line 24 or 24 'is provided for each piecing device 37 according to this exemplary embodiment. 6 branch from the line 5 between the pressure reducing valve 42 and the shutoff valve 51 a pressure line 5 'and from the line 6 between the pressure reducing device 43 and the shutoff valve 61 a line 6'. The lines 5 and 6 open together into the main line 24, which is only assigned to the machine side II alone, while the lines 5 'and 6' open into the main line 24 ', which is provided for the machine side I. The line 5 'contains a shut-off valve 51', which is controlled by an electromagnet 510 ', while the line 6' contains a shut-off valve 61 ', which is controlled by an electromagnet 610'. The electromagnets 510 'and 610' are connected to a piecing control device 370 of a piecing device 37, which is provided for the machine side I. By this design of the pressure control device 4, the main lines 24 and 24 'of the two machine sides I and II can be controlled completely independently of the piecing devices 37 assigned to one machine side I or II, so that synchronization of the work of these two piecing devices 37 is not necessary. Each main line 24 or 24 'has in this way two parallel lines 5 and 6 or 5' and 6 ', of which one line 5, 5' for each main line 24, 24 'has its own shut-off valve 51, 51'. The other line 6 up to and including the pressure reducing device 43 is assigned to all main lines 24, 24 'together. If desired, a separate shut-off valve 61, 61 'can also be provided for each line 6, 6', ie between pressure reducing device 43 and main line 24, 24 ', after their separation. This shut-off valve 61, 61 'has the task of shutting off or releasing the low excess pressure.

With the help of the shut-off valves 51 and 61 or 51 'and 61', it is also possible to switch off compressed air supply P _L completely for certain cases if this should be necessary for any reason.

In the same way as shown in FIG. 6 for the two machine sides I and II, groups of spinning positions which are divided differently can also be controlled by a piecing device 37, each piecing device 37 and the number of spinning positions A ', B assigned to this piecing device 37 ', C', D '... each have their own main line 24, 24' ... with corresponding shut-off valves 51, 51 '... and possibly 61, 61' ... with the associated electromagnets 510, 510 '. .. or 610, 610 '... is assigned.

A further possibility of controlling the negative pressure is shown in FIG. 7. For the shut-off valves of one or two rows of spinning positions A, B, ... or A ', B' ... (machine sides I and II) is according to FIG. 7 again a common main line 24 is provided. A pressure sensor 45 is connected to this main line 24 via a line 44 and is connected to a time delay device 46 in terms of tax. The time delay device 46 in turn is connected to the drive 420 of the pressure control device 4 in terms of control.

The pressure control device 4 can be designed in various ways, for example also in the manner shown in FIGS. 2 or 4 to 6. Alternatively, it can also be provided that the pressure control device can assume different switching positions and thereby provide the correspondingly desired pressure.

If the shut-off valve 21 is opened at a spinning station A, B ... or A ', B' ... so that compressed air P _{B is} fed to the spinning rotor 1, a pressure drop occurs in the main line 24. This pressure drop is sensed by the pressure sensor 45 connected to the main line 24, which in turn sends a switching pulse to the time delay device 46. The time delay device 46 now gives a switching pulse to the drive 420 of the pressure control device 4, so that this enables the supply of pressurized air P _LH under high pressure to the spinning rotor 1. After a preset time, the time delay device 46 causes the pressure control device 4 to reduce the overpressure to a low value P _LN . The shut-off valve 21 is then closed in connection with piecing, as described above. Thereafter, the pressure control device 4 - likewise under the control of the time control device 46 - releases the supply of compressed air P _LH which is at a high overpressure into the main line 24, so that a high overpressure can in turn build up in the main line 24 as a result of the closed shut-off valves 21 . If this has happened, the pressure control device 4 switches off the compressed air supply _PR in the main line 24. If the shut-off valve 21 is opened at a later point in time at any of the spinning positions A, B ... or A ', B' ..., a high spinning overpressure is immediately available.

As mentioned above, compressed air with high overpressure (P _RH ) is fed into the spinning rotor 1 while the spinning rotor 1 is running down. In the method described last, after opening a shut-off valve 21, the excess pressure initially drops before it rises again after being released by the pressure control device 4. This creates two pressure surges on the inner surface of the spinning rotor, which facilitate detachment of adhering fibers 90 and dirt components and also break open the fiber ring 92. If desired, this effect can be intensified by switching several times from high to low overpressure and back while the spinning rotor 1 is running down.

Also in the case of the device described last, the pressure control device 4 is designed such that at least two different overpressures P _LH , P _LN can be preset and, depending on the execution of the piecing process, one or the other overpressure can be called up for the supply to the shut-off valve 21.

Claims (23)

1. An open end spinning arrangement with a spinning rotor and with a compressed air conduit which is directed towards the internal surface of the spinning rotor, for cleaning purposes, and communicates via a check valve with compressed air, characterised by a switching arrangement (7; 22, 23; 51; 51, 61; 45, 46) which loads the compressed air conduit (2) alternately with a higher (P_LH) and with a lower super-pressure (P_LN).
2. An arrangement according to Claim 1, characterised by a pressure controlling arrangement (4) and a pressure sensor (45) which scans the pressure between the pressure controlling arrangement (4) and the check valve (21) and is connected via a time delay arrangement (46) to the pressure controlling arrangement (4).
3. An arrangement according to Claim 2, characterised in that the pressure controlling arrangement (4) comprises parallel conduits (5, 6), one conduit (6) of which contains a pressure lowering arrangement (43).
4. An arrangement according to Claim 2 or 3, characterised in that the switching arrangement (7) is or can be associated with the spinning arrangement (A, B, C, D, E, F, A', B', C', D', E', F') and is connected in terms of control to the pressure controlling arrangement (4).
5. An arrangement according to Claims 3 and 4, characterised in that the check valves (21) of a plurality of similar open end spinning arrangements (A, B, C, D, E, F, A', B', C', D', E', F') are connected on the inlet side with the parallel conduits (5, 6) of the pressure controlling arrangement (4), the pressure lowering arrangement (43) of which can be connected on the upstream side of the check valve (21) by means of a switching arrangement (7).
6. An arrangement according to Claim 5, characterised in that the switching arrangements (7) are designed as change-over valves (22, 23) by means of which the check valves (21) of the individual open end spinning arrangements (A, B, C, D, A', B', C', D') can be connected selectively to one or other of the two parallel conduits (5, 6).
7. An arrangement according to Claim 5, characterised in that the check valves (21) are connected via a common main conduit (24, 24') to the pressure controlling arrangement (4).
8. An arrangement according to Claims 5 and 7, characterised in that a change-over arrangement (23) which can be controlled by the switching arrangements (7) which are connected or can be connected to the individual open end spinning arrangements (A, B, C, D, A', B', C', D') is provided between the parallel conduits (5, 6) of the pressure controlling arrangement (4) and the main conduits (24).
9. An arrangement according to one or more of Claims 3 to 8, characterised in that the conduit (5) arranged in parallel with the conduit (6) with the pressure lowering arrangement (43) comprises a check valve (51) for blocking or releasing the high super-pressure.
10. An arrangement according to one or more of Claims 7 to 9, characterised in that a separate check valve (61, 61') is provided for blocking or releasing the low super-pressure between the pressure lowering arrangement (43) and the main conduit (24, 24').
11. An arrangement according to Claim 10, characterised in that, between the main conduit (24,24') and the check valve (61,61') for blocking or releasing the low super-pressure, there is provided a non-return valve (62) which protects this check valve (61,61').
12. An arrangement according to Claims 2 to 11, characterised in that the pressure controlling arrangement (4) is connected in terms of control to a piecing arrangement (37) capable of travelling along the open end spinning arrangements (A, B, C, D, E, F, A', B', C', D', E', F' ) and comprising an actuator which can be connected to the check valves (21) and/or switching arrangements (7) of the individual open end spinning arrangements (A, B, C, D, E, F, A', 3', C', D', E', F').
13. An arrangement according to claim 12, with several travelling piecing arrangements, characterised in that the piecing arrangements (37) are coupled by means of a common control arrangement (52) in such a way that the actuator of only one of the piecing arrangements (37) is active at any time.
14. An arrangement according to one or more of Claims 7 to 13, with several piecing arrangements, characterised in that each travelling piecing arrangement (37) is provided with a separate main conduit (24, 24').
15. An arrangement according to Claim 14, characterised in that each main conduit (24; 24') comprises, at its inlet end, two parallel conduits (5, 6; 5', 6') of which one conduit (6), including the pressure lowering arrangement (43) is allocated to all main conduits (24; 24') in common whereas the other conduit (5; 5') has a separate check valve (51, 51') for each main conduit (24; 24').
16. A method of starting up an open end spinning arrangement with a spinning rotor which is initially stopped for preparation of the piecing process and is cleaned by means of compressed air during deceleration until it comes to a standstill, wherein fibres are supplied to the open end spinning arrangement once the rotor is at a standstill and are then discharged again by an air stream, and the piecing process is then carried out using an arrangement according to one or more of Claims 1 to 15, characterised in that the compressed air is conveyed into the spinning rotor at high pressure during preparation for the piecing process in order to clean the spinning rotor and subsequently, but still before introduction of fibres into the spinning rotor has commenced, is reduced to a low value and is finally shut off before the yarn is returned into the spinning rotor.
17. An arrangement according to Claim 16, characterised in that the moment for changing over from high to low super-pressure is selected as a function of the slowing down behaviour of the spinning rotor which is to be stopped.
18. A method according to Claim 16 or 17, characterised in that the low value of the super-pressure is between 10% and 40% of the high value of the super-pressure.
19. A method according to one or more of Claims 16 to 18, characterised in that a-change-over from high to low superpressure and back is effected once or several times as the spinning rotor slows down.
20. A method according to one or more of Claims 16 to 19, characterised in that the fibres supplied to the open end spinning arrangement once the rotor has come to a standstill are introduced into the spinning rotor and the feeding of fibres into the spinning rotor is interrupted again at a predetermined time interval before the piecing process, the compressed air being kept reduced to a low value throughout the entire duration of the supply of fibres into the spinning rotor.
21. A method according to one or more of Claims 16 to 20, characterised in that the low value of the compressed air is maintained even after completion of the temporary supply of fibres into the spinning rotor until the beginning of the renewed run up of the spinning rotor.
22. A method according to one or more of Claims 16 to 21, characterised in that, after interruption of the supply of compressed air into the spinning rotor during the piecing operation, the high super-pressure is made available again without entering the spinning rotor.
23. A method according to one or more of Claims 16 to 22, characterised in that the piecing operation is monitored and, if it fails, preparation of a new piecing process is initiated.

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