EP0395880A1 - Method and device for joining of yarn in an open-ended rotor spinning machine - Google Patents

Abstract

At a piecing speed, a thread (30) is supplied to the fiber collecting surface of a spinning rotor (100), connected there with the fibers of a fiber ring (32) and then, with continuous integration, fibers newly fed into the spinning rotor (100) as a continuous thread from the spinning rotor ( 100) deducted again. The rotor speed is brought up from the piecing speed immediately after attachment to a speed that is lower than the piecing speed. The rotor speed is then increased again to the production speed. In this way, optimal conditions are achieved with respect to rotation propagation and withdrawal of the piecing. To carry out this method, means are provided for reducing the rotor speed from the starting speed to a lower value, means for re-accelerating the rotor speed after a desired minimum value or a period of time provided for this has been reached, and means for appending the ramping rotor speed to the desired production speed.

Description

The present invention relates to a method for spinning a thread on an open-end spinning device working with a spinning rotor, in which a thread end is delivered to the fiber collection surface at an attachment speed of the spinning rotor, connected there to the fibers of a fiber ring and then newly integrated into the spinning rotor with continuous integration fed fibers is withdrawn as a continuous thread from the spinning rotor, and a device for performing this method.

Rotor spinning devices operate at extremely high rotor speeds of 100,000 rpm and more. The thread is spun at the highest possible production speed, to which, depending on the fiber material, the spinning conditions are matched by appropriate selection of the spinning rotor, the thread take-off nozzle, etc.

For this reason, in practice, piecing is usually carried out at a lower rotor speed, which is kept constant for the duration of the piecing (DE-OS 2,058,604). The piecing can also be initiated at a lower rotor speed which the spinning rotor passes through when it starts up from standstill (DE-PS 2,321,775). In both cases, the piecing rotor speed deviates significantly from the production rotor speed, so that there are no optimal spinning conditions in this critical working phase. It is therefore often necessary to adapt to these low rotor speeds by appropriately selecting the spinning rotor and thread take-off nozzle, which, however, leads to the fact that the desired high rotor speeds can then no longer be maintained during production. In the second case, the piecing conditions become even more critical due to the increasing rotor speed.

The object of the invention is therefore to provide a method and a device which increase the piecing security.

This object is achieved in that the rotor speed is brought up from the preparation speed to a speed which is lower than the preparation speed, and only then is the rotor speed increased again to the production speed. The tightening speed at which the contact between the thread end and the fiber ring takes place is therefore relatively high, possibly even corresponds to the production rotor speed, so that the required propagation of rotation from the thread section located in the thread take-off tube to the overlap area of the thread end and fiber ring is ensured is and there is no danger that, as in the prior art, this will take place only incompletely, uncontrolled or, under certain circumstances, not at all. The relatively high rotor rotation during attachment, ie during the return of the thread end to the fiber collecting surface, has the effect that due to the good propagation of rotation in the piecing area, the latter has a high strength, which counteracts thread breaks. Even after the start of thread take-off, the fiber ring continues to grow beyond the normal dimension until the thread take-off point in the spinning rotor has rotated once. Since the rotor speed decreases after the attachment for pulling off the mass-increasing part of the fiber ring, the increase in mass of the fiber ring is completely or at least largely compensated for by the speed reduction, so that an essentially constant thread tension is achieved during the removal of the piecer from the spinning rotor. This counteracts the risk of thread breaks, since this ensures that the thread tension does not exceed the permissible values.

The reduction in the rotor speed can be ended depending on various criteria, e.g. B. depending on the thread tension, but it has proven to be useful to end this reduction depending on a predetermined time or depending on reaching a predetermined minimum rotor speed.

In order to be able to control the attachment particularly precisely, without the rotor speed in unbe due to different tolerances between the contact between the thread end and the fiber ring changes tunable, it can be provided that the setting speed before the return of the thread end to the fiber collecting surface is temporarily kept constant and is only reduced in the time between the return of the thread end and the start of the thread take-off.

It has been shown that the starting speed of the spinning rotor can be controlled in a particularly simple manner if it accelerates from standstill to a speed above the starting speed and is brought up to the starting speed from this speed. This speed, which is higher than the starting speed and on the basis of which the rotor speed is reduced, can be the production speed or a speed lying between the production speed and the setting speed.

In order to reduce the speed of the spinning rotor from the attachment speed in a rapid manner, it can be provided in an advantageous development of the method according to the invention that the lowering of the rotor speed begins at a speed above the attachment speed and is continued during the piecing process.

In principle, it is possible to reduce the rotor speed only until the massive piecer has left the inside of the rotor and has entered the thread take-off tube, where it is no longer exposed to centrifugal forces. However, it is often attempted that the thread section following the piecer not only meet the production conditions as soon as possible not only in terms of its mass, but also with regard to its rotation speaks. In order to achieve this, it is preferably provided according to the invention that the rotor speed after the removal of the mass-increasing part of the fiber ring is further reduced until the accelerating thread take-off speed and the decreasing rotor speed have reached a certain desired ratio to one another, whereupon the rotor speed and the Thread take-off speed can be accelerated to the production speed. With this desired ratio of rotor speed and thread take-off speed, these can have reached substantially the same percentage value compared to the respective production values, but this desired ratio can deviate from that which is given at production speed by one section of yarn while the rotor speed is still reduced generate at increased speed.

The end of the reduction in the rotor speed can be determined empirically, as a result of which a rough adaptation to the thread take-off speed is achieved. This is sufficient in most cases. In order to achieve an even more exact adjustment, it can be provided in a further embodiment of the method according to the invention that the thread take-off speed is monitored and, when the rotor speed reaches the same percentage value of the production value as the thread take-off speed, the reduction in the rotor speed is ended.

So that the correct twist in the yarn is not only achieved when the rotor speed has ended and then only after reaching the production values, but once the same percentage values have been reached - with respect to production ratios - of rotor speed and thread take-off speed, it is provided according to a preferred embodiment of the method according to the invention that the particular desired ratio is the same as at production speed and from the moment at which this ratio is reached, even during the subsequent acceleration of the rotor speed is maintained. This can also be determined empirically. However, it is particularly expedient if the thread take-off speed is monitored until it has reached its production value, and the rotor speed from the point in time when it reduces the same percentage value as the thread take-off speed reaches the full production value, synchronously with the increase in Thread take-off speed is accelerated.

In practice it is often provided that the spinning rotor is driven by drive means which can be brought into and out of the drive connection with the spinning rotor. In order to be able to change the rotor speed in a controlled manner in such a device, it can be provided according to a preferred development of the method according to the invention that the slip between the spinning rotor and drive means which continue to run at unchanged speed is changed.

The change in speed of the spinning rotor can in principle be controlled in any way. It has proven to be advantageous in the case of a device which has two drive means which run at different speeds when the spinning rotor uses the drive means of lower Ge to reduce its speed speed and for increasing its speed with the drive means of higher speed in drive connection. The desired braking and / or run-up behavior of the spinning rotor can be achieved by appropriate control of the slip.

To ensure that even if the contact between the returned thread end and the fiber ring to ensure good rotation propagation into the piecing at high rotor speed takes place during the pulling off of this piecing because of the large mass, the thread tension does not increase too much the reduction of the rotor speed is carried out in two phases, the first phase being essentially matched both to the propagation of rotation in the fiber ring and to the desired thread tension, and the second phase to limit the thread tension tolerances that occur to the thread tension. This two-phase reduction in the rotor speed can advantageously be achieved in that it is effected or supported in the first phase by the activation of a brake.

A further advantageous variant of the method according to the invention consists in that, in order to change the rotor speed, the spinning rotor is separated from drive means running at production speed and connected to auxiliary drive means which, according to the desired speed curve of the spinning rotor, initially slows down during piecing and later again until it is reached the production speed can be accelerated, whereupon the spinning rotor from the auxiliary drive means separated and connected to the drive means running at production speed.

In order to adapt not only the rotation of the newly spun thread, but also the thread number as quickly as possible to the values of normal production, it is expediently provided that the condition of the fiber beard, which the fiber ribbon was exposed to during the spinning process, at the beginning of the action of the rotating opening roller of the piecing process is determined and the acceleration of thread take-off speed and rotor speed takes place as a function of the determined fiber beard.

It is not necessarily the case that when certain thread tension values are exceeded, the thread always breaks, even if the risk of thread breakage is already very high. In order to increase the piecing security for future piecing processes, the first of which can be carried out immediately after the threading process has just been started, it is advantageous if the thread tension in the drawn-off thread is monitored during piecing and if one is exceeded predetermined deviation from the thread tension occurring during normal production during the next piecing process, the reduction in the rotor speed is corrected in accordance with the registered deviation.

According to the invention, the thread end is returned to the fiber ring at a higher speed than the pulling off of the part of the fiber ring which increases in mass. Thus occurs during the piecing process in the thread section between on muzzle of the thread take-off tube and the thread take-off device an increased rotation in the drawn thread. So that this rotation can be reduced again before the thread is wound onto the bobbin, it is advantageous if during the time during which the thread take-off speed has not yet reached its production value, the thread is given the pull-off movement at a greater distance from the spinning rotor than after reaching the production value. As a result, the twist can be distributed over a greater thread length, so that the wound thread, despite the increased number of twists during the piecing, receives a twist which essentially does not exceed the normal twist values or only insignificantly.

In order to carry out the described method, in a generic device, means for reducing the rotor speed from the starting speed to a low value, means for re-accelerating the rotor speed after a desired minimum value or a period of time provided for this has been reached, and means for attaching the ramping rotor speed to the desired production speed provided. As a result, the spinning rotor can have its desired speed behavior in coordination with the application of the thread and the removal of the piecer.

According to an advantageous embodiment of the device according to the invention, a control device is provided, with the aid of which it is possible to coordinate the reduction and re-acceleration of the rotor speed with the return of the thread end to the fiber collecting surface such that the thread end reaches the fiber collecting surface at a rotor speed that is higher than when the fiber ring, which is partially in the spinning rotor before the start of take-off, is subsequently pulled off. This time control means that after the end of the thread has been returned to the fiber collecting surface, the rotor speed, possibly further, is reduced, so that the piecer receives the desired strength on the one hand and on the other hand the thread tension when the piecer is pulled off does not exceed the predetermined values.

In order not only to achieve an increase in attachment security, but also to be able to adapt the twist in the thread to the desired twist as quickly as possible, it is advantageous if the timing control means are assigned corresponding adjusting means for determining the duration during which the rotor speed is reduced.

According to an alternative advantageous embodiment of the device according to the invention, means for monitoring the rotor speed or the rotor speed proportional values can be provided in order to prevent the speed of the spinning rotor from falling below a predetermined minimum value. So that the rotor speed can be adapted as precisely as possible to the thread take-off speed, monitoring means for monitoring the thread take-off speed or values proportional to this speed are preferably means in addition to the means for monitoring the rotor speed or this speed, means for converting the measurement values thus obtained into percentages of the respective full values Production values and comparison means are provided for comparing the percentages of thread take-off speed and rotor speed and for triggering a switching pulse when it is reached matching percentages to finish reducing the rotor speed.

Thus, from the moment when the reducing rotor speed in relation to its operating speed reaches the same percentage value as the thread take-off started and accelerating after the thread has returned, the thread produced can have the same rotation as during undisturbed production In a further expedient refinement of the subject matter of the invention, the monitoring means are connected in terms of control to means for generating a rotor speed proportional to the thread take-off speed.

According to a preferred embodiment of the device according to the invention, in order to change the rotor speed in a spinning rotor that can be driven by a belt, a belt pressing device is provided, which is connected to the control device for changing the contact pressure and thus also the slip between the belt and the rotor shaft.

Such a development of the subject matter of the invention is particularly advantageous, in which the spinning rotor can optionally be driven by one of two belts which can be driven at different speeds, if at least the arm of a two-armed switching lever which drives the spinning rotor at a lower speed, by means of which the spinning rotor with the one or another belt can be brought into drive connection, is designed as a belt pressing device. In this way, the speed reduction depending on the selected Apply pressure faster or slower. If both arms of the switch lever are designed as belt pressing devices, the rotor acceleration can also be controlled.

In order to be able to easily control the rotor deceleration or rotor acceleration with regard to the speed profile, the contact pressure between the belt and the spinning rotor or rotor shaft is expediently determined. For this purpose, the belt pressing device is advantageously associated with an adjusting device for determining the maximum or minimum contact pressure between the belt and the rotor shaft. If a single belt is provided, the minimum contact pressure is set for the speed reduction, while the maximum contact pressure is decisive for the acceleration. The maximum contact pressure also determines the rotor deceleration and the rotor acceleration if these speed changes take place with the aid of two belts driven at different speeds.

In today's open-end spinning machines, a large number of similar open-end spinning devices are arranged side by side, which can be operated with the aid of one or more maintenance device (s) which can be moved along this large number of spinning devices. So that the maintenance device can effect the speed control of the spinning rotor in such a case in a simple manner, it is preferably provided that the belt pressure device is connected to a control lever, to which an actuation element of the maintenance device which can be controlled from the control device can be delivered.

In order to limit and define the stroke and the contact pressure of the belt with respect to the rotor or rotor shaft without having to adhere to particularly tight tolerances between the maintenance device and the open-end spinning device, the open-end spinning device expediently has a stop to limit the feed path of the Actuator of the maintenance device.

It has been shown that the rotor speed can be controlled in a simple manner by controlling the slip between the spinning rotor or its shaft and the drive means which continue to run at unchanged speed. According to a particularly suitable embodiment of the subject matter of the invention, a belt for driving the spinning rotor mounted by means of a shaft and a belt pressing device are provided, which has a roller lever carrying a belt pressing roller, which can be brought into contact with the belt by a first elastic element with its belt pressing roller, and that furthermore, a brake lever that can be advanced to the rotor shaft is assigned, which, apart from a braking position, can be brought into various relative positions with respect to the roller lever. Cooperating stops are assigned to the brake lever and the roller lever, with the aid of which the roller lever can be lifted off the belt with its belt pressure roller when the brake lever moves into its braking position. The brake lever and the roller lever are connected to each other via a weaker elastic element compared to the first elastic element, by means of which the belt contact pressure caused by the first elastic element can be reduced by changing the relative movement between the brake lever and the roller lever. Hereby the slip between the belt and the rotor shaft is controlled depending on the relative position of the brake lever relative to the roller lever. Depending on the required braking or acceleration behavior of the spinning rotor, this device can be used both for reducing the speed and for increasing the speed of the spinning rotor when the rotor speed is not reduced after piecing, and is therefore of independent importance.

Such an embodiment of the device according to the invention has proven to be particularly advantageous in which the roller lever has two arms, one arm of which carries the belt pressure roller and is acted upon by the second elastic element, while the arm facing away from the belt pressure roller is acted upon by the first elastic element .

To control the acceleration behavior, according to a further expedient embodiment of the subject matter of the invention, a belt for driving the spinning rotor mounted by means of a shaft and a belt pressing device can be provided, which has a roller lever carrying a belt pressure roller, which can be lifted off the rotor shaft by a brake lever and to which a controllable damping device is assigned is. Such a damping device for controlling the acceleration behavior of a spinning rotor can also be used regardless of whether or not the speed of the spinning rotor is reduced after piecing. Such a damping device is therefore of independent importance.

The damping device can be designed differently, e.g. as a controllable hydraulic or pneumatic piston. According to a preferred embodiment, the damping device is designed as a plate spring mounted on the pivot axis of the roller lever, which is assigned a load element that is adjustable parallel to the pivot axis.

It is not absolutely necessary for the maintenance device to act mechanically on elements of the open-end spinning device in order to be able to control the rotor speed. In an alternative advantageous embodiment of the subject matter of the invention it can be provided that the belt pressing device is assigned to each open-end spinning device its own actuating device, via which the belt pressing device is connected to the control device. This connection to the actuating device can be made electrically, inductively or in another suitable manner, so that the belt pressing device can be actuated in the desired manner at the desired time on the basis of corresponding control commands from the control device.

Instead of or in addition to the belt pressing device, a brake with controllable braking action can also be provided, which can be brought into effect in the desired manner on the spinning rotor or the rotor shaft in order to achieve the desired rotor speed curve.

According to an advantageous embodiment of the device according to the invention, a brake lever can be provided which brakes direction can be actuated via an elastic element and in the lifting direction via a rigid stop by a control element.

It is also not necessary to drive the spinning rotor of the or each spinning station by means of a drive belt or the like. The invention can also be implemented if an individual drive motor is provided for the spinning rotor. In this case, the control device preferably contains a generator for generating electrical values, by means of which the speed of the spinning rotor is controlled in the desired manner.

According to a further advantageous embodiment of the subject matter of the invention, two drive means which can optionally be brought into action with the spinning rotor are provided, one of which serves to simultaneously drive a plurality of spinning rotors, while the others only serve to drive a single spinning rotor. In such a case, it is advantageously provided that the drive means provided for driving an individual spinning rotor are connected in terms of control to the control device and can be controlled thereby.

If the thread draw is controlled as a function of the combed state of the fiber beard, then in an advantageous further development of the device according to the invention it is provided that the control device is connected to a device for the early maintenance of the desired yarn twist, which combs the combed state of the fiber beard at the time the thread end is returned to the Quilt area determined and depending on the determined Aus Combing not only controls the thread take-off, but also the rotor speed.

If the predetermined limit values for the thread tension are exceeded, the thread does not necessarily break, but there is a risk that subsequent piecing attempts will fail. For this reason, a thread tension meter monitoring the thread tension is expediently provided, which is connected for control purposes to the control device, furthermore means for comparing the measured thread tension with a predetermined reference tension and means for changing the data stored in the control device are provided in such a way that when the next piecing process, the rotor speed is reduced so that thread tension deviations are reduced. In such an embodiment of the subject matter of the invention, it can be advantageous if the control device contains means which store the average value of the thread tension in the case of undisturbed production as a reference value. In such a case, there is no need for separate setting means for entering such a reference value.

The invention offers a solution for the first time, such as the contrary demands for conditions during the actual piecing, which fully or at least largely correspond to the normal operating conditions, and for low thread tensions when the piecing tool is pulled off, which - based on the same lengths - is a multiple of the normal Has thread mass, can be met. The device is simple in construction and can be used in conjunction with all the usual rotor drive mechanisms Devices find application. The invention thus enables an increase in piecing security.

• Figur 1 schematisch die Anspinnverhältnisse im Spinnrotor;
• Figur 2 in schematischer Darstellung den Masseverlauf in einem Ansetzer;
• Figur 3 in schematischer Darstellung eine Gegenüberstellung der Rotordrehzahl, der Fadenabzugsgeschwindigkeit sowie der Fadenspannung während des Anspinnens gemäß dem erfindungsmäßen Verfahren;
• Figur 4 und 5 Abwandlungen des in Fig. 3 gezeigten Verfahrens in schematischer Darstellung;
• Figur 6 in schematischer Darstellung einen Faserbart, der nach dem Stillsetzen des Faserbandes der Wirkung einer Auflösewalze unterschiedlich lange ausgesetzt wurde;
• Figur 7 in schematischer Gegenüberstellung den Einfluß unter­schiedlicher Stillstandszeiten des Faserbandes auf das Einsetzen der Faserspeisung sowie die hieran ange­paßte Fadenabzugsgeschwindigkeit;
• Figur 8 und 9 die Antriebsvorrichtung einer Offenend-Spinnvorrich­tung mit einer erfindungsgemäß ausgebildeten Riemen­anpreßvorrichtung in schematischer Ansicht;
• Figur 10 im Querschnitt eine Spinnstelle mit einer erfindungs­gemäßen Offenend-Spinnvorrichtung;
• Figur 11 im Schema die steuermäßigen Verknüpfungen von Faden­abzug und Rotorantrieb;
• Figur 12 im Schema eine Abwandlung der erfindungsgemäßen Vor­richtung, mit deren Hilfe sowohl die Reduzierung der Rotordrehzahl als auch der anschließende Rotordrehzahl gesteuert erfolgen kann;
• Figur 13 eine erfindungsgemäß ausgebildete Offenend-Spinnvor­richtung, die zur Steuerung der Rotordrehzahl eine gesteuerte Rotorbremse aufweist;
• Figur 14 in schematischer Darstellung die Rotordrehzahl und die Fadenabzugsgeschwindigkeit bei einem abgewan­delten Verfahren;
• Figur 15 in schematischer Seitenansicht eine Antriebsvor­richtung einer Offenend-Spinnvorrichtung mit steuer­barer Riemenanpreßvorrichtung; und
• Figur 16 in schematischer Seitenansicht eine Antriebsvor­richtung einer Offenend-Spinnvorrichtung mit einer abgewandelten steuerbaren Riemenanpreßvorrichtung und mit einer steuerbaren Bremsvorrichtung.

Embodiments of the invention are explained in more detail below with reference to drawings. Show it

• Figure 1 shows schematically the piecing conditions in the spinning rotor;
• Figure 2 shows a schematic representation of the mass profile in a piecer;
• Figure 3 is a schematic representation of a comparison of the rotor speed, the thread take-off speed and the thread tension during piecing according to the inventive method;
• Figures 4 and 5 modifications of the method shown in Figure 3 in a schematic representation;
• FIG. 6 shows a schematic representation of a fiber beard which was exposed to the action of a dissolving roller for different lengths after the fiber sliver had stopped;
• FIG. 7 shows a schematic comparison of the influence of different downtimes of the sliver on the onset of fiber feeding and the thread take-off speed adapted to it;
• FIGS. 8 and 9 the drive device of an open-end spinning device with a belt pressing device designed according to the invention in a schematic view;
• Figure 10 in cross section a spinning station with an open-end spinning device according to the invention;
• Figure 11 in the scheme the tax-related links of thread take-off and rotor drive;
• FIG. 12 shows a modification of the device according to the invention, with the aid of which both the reduction in the rotor speed and the subsequent rotor speed can be controlled;
• FIG. 13 shows an open-end spinning device designed according to the invention, which has a controlled rotor brake for controlling the rotor speed;
• FIG. 14 shows a schematic representation of the rotor speed and the thread take-off speed in a modified method;
• FIG. 15 shows a schematic side view of a drive device of an open-end spinning device with a controllable belt pressing device; and
• Figure 16 is a schematic side view of a drive device of an open-end spinning device with a modified controllable belt pressing device and with a controllable braking device.

First, the structure of an open-end spinning device 10 having a spinning rotor 100 will be described with reference to FIG. 10, in order to be able to use this later in the explanation of the problem to be solved.

The open-end spinning device is part of an open-end spinning machine 1, along which a maintenance device 2 can be moved.

Each open-end spinning device 10 has a fiber feeding or delivery device 11 and a dissolving device 12. In the exemplary embodiment shown, the delivery device 11 consists of a delivery roller 110 with which a feed trough 111 cooperates elastically. The feed trough 111 is pivotally mounted on an axis 112, which also carries a clamping lever 113, which is designed as a guide element for a sliver 3 and can be brought into contact with the feed trough 111 by means of an electromagnet 114 or can be lifted off the latter again. In the exemplary embodiment shown in FIG. 10, the opening device 12 is essentially designed as a opening roller 121 arranged in a housing 120. A fiber feed channel 122 extends from it to the spinning rotor 100, from which the spun thread 30 is drawn off through a thread draw-off tube 101.

The spinning rotor 100 is located in a housing (not shown), which is connected to a vacuum source (also not shown) in order to generate the required negative vacuum. The entire open-end spinning device 10 including delivery device 11 and opening device 12 is covered by an openable cover 13.

For the withdrawal of the thread 30 from the spinning rotor 100 during the undisturbed spinning process, a pair of take-off rollers 14 is used with a take-off roller 140 driven at production speed and a pull-off roller 140 which rests elastically on the driven take-off roller 140 and is driven by it by entrainment. On its way between thread take-off tube 101 and Draw-off roller pair 14, the thread 30 is monitored by a thread monitor 15.

The thread then arrives at a winding device 16, which has a driven winding roller 160. The spooler 16 also has a pair of pivotable spool arms 161 that rotatably hold a spool 162 therebetween. The bobbin 162 lies on the winding roller 160 during the undisturbed spinning process and is consequently driven by it. The thread 30 to be wound onto the spool 162 is inserted during the undisturbed spinning process into a traversing thread guide 163 which is moved back and forth along the spool 162 and thereby ensures a uniform distribution of the thread 30 on the spool 162.

The maintenance device 2, which can be moved along the open-end spinning machine 1, has a control device 20 which is connected to a swivel drive 210 of a swivel arm 21 which at its free end carries an auxiliary drive roller 211. The auxiliary drive roller 211 is driven by a drive motor 212, which is also connected to the control device 20 for control purposes.

The swivel arms 161 can be supplied with swivel arms 22 which are also pivotably mounted on the maintenance device 2 and whose swivel drive 220 is in a control connection with the control device 20.

During the undisturbed, normal production operation, the sliver 3 is presented with the help of the rotating delivery roller 110 and the feed trough 111, which is elastically pressed against this delivery roller 110, of the opening roller 121, which dissolves the sliver 3 into fibers 31, which are then passed through the fiber feed channel 122 into the interior of the Spinning rotor 100 are promoted, where they deposit in the form of a fiber ring 32. The thread 30 in the take-off is connected to this fiber ring 32 and rotation is given by the rotation of the spinning rotor 100. This rotation is propagated into the fiber collecting groove in which the fiber ring 32 is formed, whereby the fiber ring 32 is continuously screwed into the end of the thread 30 and is thus connected to it. The thread 30 drawn off from the spinning rotor 100 with the aid of the pair of draw-off rollers 14 is wound onto the bobbin 162 lying on the bobbin roller 160 during production, the thread 30 being oscillated by the traversing thread guide 163 for uniform winding on the bobbin 162.

If a thread break occurs, which is registered by the thread monitor 15 due to the absence or drop of the thread tension, the bobbin 162 is lifted off the winding roller 160 by means not shown, whereby the bobbin 162 is stopped. In addition, the thread monitor 15 sends a control pulse to the electromagnet 114 which actuates the clamping lever 113 and thus clamps the sliver 3 between itself and the feed trough 111. In addition, this pivoting movement of the clamping lever 113 causes the feed trough 111 to pivot away from the delivery roller 110, so that the sliver 3 can no longer be fed to the opening roller 121

If the maintenance device 2, which has reached the open-end spinning device 10 to be serviced in a known manner by means of a call device (not shown) or because of its customary patrol travel along the machine, the yarn break is eliminated in the usual manner. After the usual preparatory work (cleaning the spinning rotor 100, searching for the end of the thread on the spool 162 and pulling the thread therefrom, cutting to length and preparation of the end of the thread, releasing the previously stopped spinning rotor 100), the fiber feed is released by actuating the electromagnet 114 again, so that now fibers 31 again enter the spinning rotor 100 and in turn form a fiber ring 32 there. At a point in time coordinated with this, the thread end is returned to the fiber collecting surface 102 (see FIG. 1) of the spinning rotor 100 which is designed as a fiber collecting groove, the thread end 300 depositing over part U 'of the circumference U of the fiber collecting surface 102 and its radial intermediate region 301 the position 301a occupies. After a short stay on the fiber collecting surface 102, the thread end 300 is subjected in a known manner to a thread draw-off which now runs up to its production value. The thread end 300 is tensioned and reaches the position 301b with its intermediate region 301. The thread end 301 pulls on the fiber ring 32 so that, viewed in the circumferential direction of the fiber collecting surface 102, fibers extend from the thread end 300 to the fiber ring 32 on both sides from the attachment point 320 and form fiber bridges 321 and 322. When the thread take-off continues, the intermediate region 301 of the thread end 300 reaches the position 301c. The fiber bridges 321 and 322 tear and wind in the form of wild windings 323 around the thread end 300. The size of the fiber bridge 322 and thus the size of the accumulation of windings 323 essentially depends on the size of the diameter of the spinning rotor 100.

2 shows a piecing device 33 in two different ways. As can be clearly seen from this figure, a piecing device 33 generally has three length sections 330, 331 and 332.

The first length section 330 is formed by the overlap region of the returned thread end 300 and the fiber ring 32 which is already in the spinning rotor 100 at the time the thread is returned. This length section 330 also contains the wild turns 323 which are formed from the fiber bridge 322 (see FIG. 1). Since the delivery device 11 continues to deliver new fibers 31 to form a fiber ring 32 on the fiber collecting surface 102, the fiber ring 32 is reinforced by the newly fed fiber mass 324.

The second length section 331 of the piecing device 33 also has a reinforced cross-section, which stems from the fact that even after the beginning of the thread take-off, an additional fiber mass 324 enters the spinning rotor 100 through the continuous supply of fibers 31, whereby the fiber ring 32 until the first revolution is completed of the attachment point 320 in the spinning rotor 100 generally has a mass that is greater than the mass after the first revolution of the attachment point 320.

The first length section 330, which is formed by the overlap region of thread end 300 and fiber ring 32, has such a length, which is given by the aforementioned part U 'of the circumference U of the spinning rotor 100. The two length sections 330 and 331 together have a length that is predetermined by the circumference U of the spinning rotor 100.

Ideally, if, after deducting the length sections 330 and 331, the thread take-off speed and the fiber feed effective in the spinning rotor 100 run synchronously, the piecing device 33 has already reached the desired thickness from the end of the length section 331, so that the third length section 332 mentioned is omitted in this case. In all other cases, however, the two length sections 330 and 331 are followed by a third length section 332, which is either stronger or weaker than the thread 30 and can have different lengths. The deviation of this length section 332 from the nominal thickness of the thread 30 depends on whether it has been possible to bring the fiber feed and thread take-off to the same percentage value of their production values by the end of the length section 331.

In the area of the length section 330, it is unavoidable that it has an increased cross section. This is particularly due to the fact that in order to produce a secure connection between the thread end 300 and the fiber ring 32, the thread end 300 on the one hand and the fiber ring 32 on the other hand must have a sufficiently large mass. If the thread end 300, which, of course, can have a tapered shape in a known manner by appropriate pretreatment, does not have sufficient mass, a thread break will occur in this area.

If, on the other hand, the fiber ring 32 is not strong enough, the length region 330 will be followed by a second length region 331 beginning with a thin point, the risk of thread breakage being particularly great in this region 333. In order to remedy this, the procedure according to FIG. 3 deviates from the previously known prior art. This figure shows a schematic comparison of the speed V _{A of} the thread take-off and the speed n _{R of} the spinning rotor 100 in percent, the base line representing 0%, while the upper limit line indicates 100% of the respective production speed or speed. Of interest for the description in connection with the problem to be corrected is only the curve from the time t 1, which characterizes the return delivery R _{F of} the thread end 300 on the fiber collecting surface 102. Thus, the course of the speed V _A or the speed n _{R can take place} before this time t 1 in the usual (and therefore not shown) manner. After returning the thread end 300 to the fiber collecting surface 102, the thread end 300 is subjected to the thread draw-off after a short dwell time t _v , which is now carried out with increasing speed V _{A runs up} to the production value (100%) that it reaches at the time t₂.

Simultaneously with the return delivery R _{F of} the thread end 300 to the fiber collecting surface 102, the speed n _{R of} the spinning rotor 100 is started to be reduced, so that the thread end 300 reaches the fiber collecting surface 102 of the spinning rotor 100 at a rotor speed which is higher than when it is subsequently drawn off of the piecing 33 forming fiber ring 32. At the time t₃, the speed reduction is ended, whereupon the spinning rotor 100 can run up to its full speed n _R (100%), which it reaches according to FIG. 3 at the time t₆, ie only after it has been reached the full speed V _A through the thread draw.

At the beginning of the return of the thread end 300 to the fiber collecting surface 102, ie at the beginning of the attachment, the attachment speed is still at the production speed, ie the spinning rotor 100 still has its full speed n _R (100%) at this point in time, which is the case in the exemplary embodiment shown The start of thread take-off (see speed V _A ) is only approx. 94% of the full speed (100%). The reduction in the speed n _R is continued for a predetermined period of time, except for a speed that is lower than the starting speed of the spinning rotor 100. In the exemplary embodiment shown, the speed reduction is ended in a time-dependent manner, namely at the point in time t der at which the piecing device 33 has entered the thread draw-off tube 101, so that this piecing device 33 no longer has any radial forces due to the rotor rotation in the drawdown Thread 30 can arise. The spinning rotor 100 is then accelerated again to its full speed n _R.

The cross-sectional profile of the newly spun thread 30 is shown in the lower part of FIG. 2. In FIG. 3, taking into account the respectively effective rotational speed n _{R of} the spinning rotor 100, the tension S _F in the thread was derived from the cross-sectional profile of the thread 30 and entered on the same scale.

During the dwell time tv of the thread end 300 on the fiber collecting surface 102 of the spinning rotor 100, the latter still has almost its full speed n _R. Thus, the conditions in the spinning rotor 100 still essentially correspond to those conditions which are effective during the normal production process. It is therefore not only a certain number of real turns generated in the thread 30 depending on the number of rotor revolutions, but due to the high effective centrifugal forces (see high thread tension S _F '), a high false wire is also generated, which propagates to the tie-in point 320 is and ensures that a firm connection between thread end 300 and fiber ring 32 is generated.

At the beginning of the withdrawal of the piecing device 33 there is a large increase in the thread tension S _F up to a multiple of the thread tension effective during the normal spinning conditions, although the speed n _{R of} the spinning rotor 100 is already reduced compared to the production. However, this tension peak cannot be avoided because of the required overlap of thread end 300 and fiber ring 32. After deducting this length range 330 (time t₅) is largely compensated for the increasing mass of the piecing 33 by the further decreasing speed n _{R of} the spinning rotor 100, so that the thread tension S _F is kept essentially constant or at least within tolerable limits, so that there is no danger due to the thread tension S _F there is more of a thread break.

When the piecing device 33 has left the inside of the spinning rotor 100, the spinning rotor 100 is accelerated again to its operating speed.

FIG. 4 shows a modification of the method previously described with the aid of FIG. 3. The main difference is that the reduction in the speed n _{R of} the rotor already begins (time t 1 ') before the thread end 300 reaches the fiber collecting surface 102 of the spinning rotor 100, ie the reduction in the rotor speed begins at a speed above the starting speed. In this modified method, the preparation speed is therefore below the production speed. Furthermore, the reduction in the rotational speed n _{R of} the spinning rotor is also continued during the withdrawal, possibly even after the deduction of the mass-increasing part of the fiber ring, which increases until the first revolution of the attachment point 320 and thus has the length of a circumference U, until the decreasing speed n _{R of} the spinning rotor 100 and the accelerating speed V _{A of} the thread take-off have a desired relationship to one another. This ratio can be the same as for the spinning station production speed. However, it may also be a different Ver Ratio can be provided, for example to generate a thread section with increased rotation to compensate for the low rotor speed and thus also the low centrifugal forces. If the desired ratio should correspond to the production conditions, the rotor speed and the thread take-off must have reached essentially the same percentage value - in each case based on the respective production values.

4, the speed n _{R of} the spinning rotor 100 has already dropped to approximately 90% of the full speed n _{R of} the spinning rotor 100 at the start of the thread take-off, so that the centrifugal forces acting on the thread 30 are already significantly reduced. Nevertheless, the rotor speed is close to the production speed (100%), so that it is ensured that enough rotation can be introduced into the attachment point 320 to ensure a secure connection between the thread end 300 and the fiber ring 32. Due to the further decreasing speed n _{R of} the spinning rotor 100, a drop in the thread tension is achieved, which is therefore below the normal spinning tension. In the short term, the thread tension increases during the period in which the length section 331 is withdrawn from the spinning rotor 100 until the thread tension S _F decreases again towards the end of the withdrawal of this length section 331.

The reduction in the rotor speed is continued after the two longitudinal sections 330 and 331 of the piecing device 33 have been pulled off, so that the spinning rotor 100 reaches a speed n _R as quickly as possible which, as a percentage, corresponds to the speed V _{A of} the thread take-off.

In Fig. 2 in the length section 332 is shown in broken lines that at a speed V _{A of} the thread take-off, which is adapted to the effect of the fiber feed in the spinning rotor 100, a thick spot in the thread 30 can be avoided, so that in such a case the thread 30 already has its target strength from time t₄. By continuously reducing the speed n _{R of} the spinning rotor 100 beyond the time t₄, it is achieved that from the time t₇ at which the speed n _{R of} the spinning rotor 100 and the speed V _{A of} the thread take-off reach the same percentage value of the production values (in shown embodiment at about 76% of the production values), the thread 30 produced not only has the desired strength, but also the desired rotation.

After reaching the desired ratio - which may differ from that at production speed - the rotor speed and the thread take-off speed are accelerated. If the desired ratio already coincided with that at production speed, this will also be maintained during acceleration. If, on the other hand, the desired ratio differs from the production ratio, the ratio between the rotor speed and the thread take-off speed can be adjusted during the joint acceleration of the thread take-off and the rotor speed, but it is also possible to adopt this production ratio only when either the thread take-off speed or the rotor speed already has the Has reached production value.

Another modification of the previously be with the help of FIGS. 3 and 4 The method described will now be explained with the aid of FIG. 5. In this example, the spinning rotor 100 is only braked after the return RF of the thread end 300 to the fiber collecting surface 102 of the spinning rotor 100 (time t _{1 Zeitpunkt} ), so that the starting speed of the spinning rotor 100 corresponds to its production speed. As a result, the thread end 300 is still exposed to the full speed n _{R of} the spinning rotor 100 when it is returned R _F , that is to say when it is attached, and as a result reaches the fiber collecting surface 102 very quickly and can there also very quickly make contact with the fibers 31 of the fiber ring 32. The production and propagation of false wire in the integration point 320 is correspondingly good.

On the other hand, however, to keep the thread tension as low as possible at the time of the start of the thread take-off, the speed n _{R of} the spinning rotor 100 is reduced extremely rapidly between the times t _1˝ and t₃. As shown in Fig. 2, the thread mass and thus the tension in the drawn thread 30 increases between the times t₃ and t₅ and t₅ and t₄ again. In order to nevertheless achieve a constant thread tension, the speed of the spinning rotor n _{R is} further reduced, however in a manner adapted to the thread mass. Assuming that the thread 30 already has its desired strength by appropriate adjustment of fiber feed and thread take-off from the time t,, the speed n _{R of} the spinning rotor 100 is accelerated again shortly before reaching the time t Erreichen, so that the spinning rotor 100 from this point in time t₄, ie with the deduction of the length section 331 of the piecing 33, the spinning rotor 100 already has 100% of its operating speed again. At this point the speed must be speed V _{A of} the thread take-off has not necessarily reached its final speed if it is only matched to the fiber feed effective in the spinning rotor 100.

Fig. 5 shows clearly - one can see from the period before the time t₃ before the start of the thread take-off - that the spinning rotor 100 is reduced in two phases in its speed n _R. The first phase between the times t₃ and t₅ is essentially matched to a good propagation of the - real and false - rotation in the fiber ring 32 and also to a thread tension not too different from the spinning tension, while the second phase alone Limitation of thread tension fluctuations is used.

Depending on whether it is more important that the thread tension S _{F is} close to the operating thread tension or whether it is more important that the rotation in the drawn-off thread 30 corresponds to the operating conditions, the speed n _{R of} the spinning rotor 100 can be reduced accordingly or accelerated again will.

In order to illustrate that by means of the described methods according to FIGS. 3 and 4 the tension peaks, which inevitably occur in the previously usual methods, the thread tension S _{F is} still in FIGS. 3 and 4 (for a rotor speed of 100%) 'Known method shown. It becomes clear that, in contrast to the known method according to the new method, the voltage tolerances can be reduced by about half.

The control of the reduction in the rotational speed n _{R of} the spinning rotor 100 as a function of time has been formed above. However, it is also possible to set the lowest speed, when the speed reduction is reached and a switch is made to increasing the speed. In this case, different values are derived from the times entered in FIGS. 3 to 5.

According to FIGS. 3 to 5 it is provided that the return of the thread end to the fiber collecting surface takes place either at full production speed (100%) of the spinning rotor 100 (see FIGS. 3 and 5) or after the reduction in speed n _R of the spinning rotor 100 has already started.

Figure 14 shows a further modification, according to which the speed n _{R of} the spinning rotor 100 during the return delivery R _{F of} the thread end 300 to the fiber collecting surface 102 of the spinning rotor 100, ie from time t₁₀ to time t₃, is kept constant (see speed n _R ' ). This constant speed n _R 'can be approached either from the production speed (100% - see time t₉) or from standstill (0 ° - see time t₈).

Maintaining a constant speed n _R 'of the spinning rotor 100 during the return delivery R _{F of} the thread end 300 has the advantage that the times can be set very precisely for the actual piecing (return delivery of the thread end 300, switching on the fiber feed, start of the new thread take-off) , since there are no different speed changes due to tolerances etc. during this time. At the latest from the time t₃ at - ie from the moment the thread take-off starts (see speed V _A ) - the speed of the spinning rotor 100 is reduced in order to achieve that the thread tension S _F is kept essentially constant or at least within tolerable limits due to the piecing .

The reduction in speed n _R ', which was kept constant before piecing, on the other hand begins at the earliest at time t 1 - ie at the time at which the return delivery R _{F of} the thread end 300 begins. The reduction in speed n _R 'of the spinning rotor 100 can thus be used depending on the respective spinning conditions between the time t 1 of the return delivery R _{F of} the thread end 300 and the time t 3 of the start of the thread take-off.

For control reasons, it may be expedient to always control the speed n _R 'of the spinning rotor 100 for pinning from above, even if the spinning rotor 100 has stood before the piecing. Such a variant has been represented in FIG. 14 by the line n _R ˝. The rotor speed is thus in this case first from the standstill to a above the piecing speed (rotational speed n _R ') lying speed accelerates and from this speed to the piecing speed (rotational speed n _R' decelerated). The speed at which the speed reduction starts is the production speed (100%) according to FIG. 14, but, if desired, a speed lying between the speed n _R 'and the production speed (100%) can be selected. This type of activation of the preparation speed is advantageous both when the preparation speed is temporarily kept constant (according to Fig. 14), but also when the speed is further reduced without interruption of the speed reduction after reaching the preparation speed and the application takes place during this speed reduction.

It was assumed above that the fiber feed into the spinning rotor 100 starts before the thread end 300 reaches the fiber collecting surface 102. However, this is not a prerequisite for carrying out the procedure. If the delivery device 11 is already switched on, but the fibers 31 are prevented from reaching the fiber collecting surface 102, but are diverted beforehand, the thread end 300 can also be returned to the fiber collecting surface 102 before the fiber flow onto the fiber collecting surface 102 is released. In this way, an extremely precise control of the piecing and the dimensioning of the piecing 33 can be controlled.

In order to be able to implement the described method, it is necessary to match the rotational speed n _{R of} the spinning rotor 100 to the piecing process, in particular the return delivery R _{F of} the thread end 300 to the fiber collecting surface 102 and the renewed removal of the thread. For this purpose, it is provided according to FIG. 10 that the control device 20 has corresponding time control means 23. Since in practice different fiber materials are spun at different speeds n _{R of} the spinning rotor 100, the time control means 23 according to FIG. 10 are equipped with setting means 230 and 231, with the aid of which the switch-on time and the switch-off time of the speed reduction of the spinning rotor 100 can be determined. Depending on how exactly the speed change Further setting means are of course also possible, but are not shown in FIG. 10 for reasons of illustration. It _{goes without saying} that either several setting means for setting the different times t₁, t₁ 'or t _1˝ , t₅, t₄, t₇, t₂ and / or t₆ can be provided. Alternatively, it is also possible to provide two setting means, of which the various points in time are entered one after the other with the aid of the first setting means, while the second setting means serves to determine the speed change, ie speed reduction or speed acceleration.

10 schematically shows a device with the aid of which the speed n _R can be changed. In this exemplary embodiment, two drive belts 17 and 18 are provided, which can be brought into drive connection with the shaft 103 of the spinning rotor 100 by control from a control device 4. In order to match the controls of the control devices 4 and 20 to one another, these are connected to one another via a line 40.

FIG. 12 shows a concrete solution of the device schematically shown in FIG. 10 for selectively driving the spinning rotor 100 with the aid of the drive belt 17 (main drive means) or the drive belt 18 (auxiliary drive means). The two drive belts 17 and 18 run in the longitudinal direction of the open-end spinning machine 1 and are supported between the individual open-end spinning devices 10 arranged next to one another by support rollers 19 and 190. To control the drive of the spinning rotor 100, a switch lever 506 is provided, which by means of a Pivot bearing 54 is mounted centrally and carries a control roller 50 and 51 at the ends of its two arms 500 and 503.

In a neutral middle position, the two control rollers 50 and 51 release the drive belts 17 and 18, which are lifted off the shaft 103 of the associated spinning rotor 100 with the aid of the support rollers 19 and 190. Drives 52 and 53 are connected to the two arms of the change-over lever 506 of each open-end spinning device 10 via suitable coupling elements, which in turn are connected to the control device 4 in terms of control. If the drive device 52 is now actuated by a corresponding control signal output by the control device 4, the control roller 50 is pressed onto the drive belt 17 assigned to it, so that the belt 17 comes into contact with the shaft 103 in its position 17 '. Similarly, the belt 18 in its position 18 'comes to rest against the shaft 103 of the spinning rotor 100 when, by appropriate control by the control device 4, the drive device 53 pivots the switching lever 506 and presses the control roller 51 against the drive belt 18.

The two drive belts 17 and 18 are driven at different speeds, so that by switching the drive of the spinning rotor 100 to one or the other drive belt 17 or 18, the spinning rotor 100 is also driven at different speeds.

Due to different stroke paths, the switch lever 506 can with different force with its roller 50 or 51 against the ordered drive belts 17 or 18 are pressed, so that this drive belt 17 or 18 also abuts with different force on the shaft 103 of the spinning rotor 100. Accordingly, the slip between the drive belt 17 or 18 on the one hand and the shaft 103 of the spinning rotor 100 is of different sizes, so that the speed change (speed reduction or speed acceleration) also takes place at different speeds corresponding to this slip.

The above description shows that in order to carry out the methods explained, it is necessary to have means by means of which the speed n _{R of} the spinning rotor 100 is reduced from the starting speed, which may also be identical to the production speed, to a lower value becomes. In the exemplary embodiment described above, these means are formed by the drive 53, the arm 503 of the switch lever 506 and the control roller 51. Means must also be provided by which the spinning rotor 100 is accelerated again. In the above exemplary embodiment, these means are formed by the drive 52, the arm 500 of the switch lever 506 and the control roller 50. And finally, means are provided which cause the ramping rotor speed to be appended to the production speed. These means are formed by the drive 52 and the switch lever 5 and its arm 500 with the control roller 50, since a correspondingly pivoting of the switch lever 506 causes a slip-free drive of the spinning rotor 100 by the drive belt 17.

The control of the rotational speed n _{R of} the spinning rotor 100 by controlling the slip can also take place with the aid of such a device (with only minor design adjustments) if only a single drive belt 17 and correspondingly only a single control roller 50 are provided, since as the size increases Slip the drive connection between the drive belt 17 and the shaft 103 of the spinning rotor 100 is reduced, so that the spinning rotor 100 is brought to a lower speed n _R , while the spinning rotor 100 is accelerated again as the slip becomes smaller. The means for reducing the rotor speed, for re-accelerating the rotor speed and for appending the rotor speed to the production speed are formed by the - in this case only one-armed - changeover lever 5.

An embodiment of a similar device is shown in FIG. 15. Instead of a switch lever 506, a two-armed roller lever 504 is provided, which has a control roller 50 at the end of its one arm 500. At the end of his other arm, a tension spring 550 engages, the other end of which is anchored at a stationary point on the machine frame.

A brake lever 562 is also provided, which is pivotably mounted on a pivot axis 563 independently of the changeover lever 506. The brake lever 562 carries a brake pad 561, which can be brought to bear against the shaft 103 of the spinning rotor 100. To control the brake lever 562, this is connected to the control link 57.

The brake lever 562 extends substantially parallel to the roller lever 504, the pivot axis 563 being located with respect to the pivot bearing 54 of the roller lever 504 on the side on which the control roller 50 is also located, while the control linkage 57 is on the side of the switching lever 506 with the arm 503. With respect to the pivot bearing 54 on the same side, the brake lever 562 carries a stop 564 which, when it hits a stop 505 on the arm 503 or on the arm 503 itself, pivots the roller lever 504 against the action of the tension spring 550. Depending on the swivel path of the brake lever 562, which is predetermined by the lifting movement of the control linkage 57, the control roller 50 is pressed more or less strongly against the drive belt 17, so that the spinning rotor 100 also differs because of the different slippage between drive belt 17 and shaft 103 which is controlled thereby is accelerated.

An even more precise control of the slip and thus the drive of the spinning rotor 100 by the drive belt 17 via the shaft 103 is obtained if the brake lever 562 and the arm 500 of the roller lever 504 are connected to one another by a tension spring 551. With such a design of a belt pressing device, the effect of the tension spring 550 is stronger than the effect of the tension spring 551. This can be achieved by different distances of the articulation points of the tension springs 550 and 551 from the pivot bearing 54 and / or by different tension springs 550 and 551.

If the brake lever 562 is removed with its stop 564 from the roller lever 504 or the stop 505 carried by it, the tension spring 550 causes the control roller 50 to engage the drive belt 17 and press it against the shaft 103 of the spinning rotor 100. The further the brake lever 562 moves away from the roller lever 504, the more the tension spring 551 is tensioned, the force of which is opposite to that of the tension spring 550. Since the force of the tension spring 550 exceeds that of the tension spring 551, the control roller cannot be lifted off the drive belt 17, but the tension spring 551 reduces the force of the tension spring 550, so that only the differential force between the effective forces of the tension springs 550 and 551 is effective . In this way, a very precise slip control between the drive belt 17 and the shaft 103 and thus an exact drive control for the spinning rotor 100 is possible in that the brake lever 562 can be brought into different relative positions with respect to the roller lever 504.

When the brake lever 562 moves into its braking position, the stop 564 comes to rest against the roller lever 504 or against its stop 505 and, as it continues its movement, lifts the control roller 50 off the drive belt 17. Finally, the brake pad 561 comes to rest against the shaft 103 and stops the spinning rotor 100.

It goes without saying that, with the appropriate arrangement and design, the tension springs 550 and 551 can be replaced by other springs, such as compression springs, or by suitable hydraulic or pneumatic means. It is according to the This elastic means can also be arranged to provide a single-armed roller lever (not shown) instead of a two-armed roller lever 504.

According to a further modification of the device described, it can be provided to reduce the slip that, instead of a tension spring 551 or another elastic coupling member between brake lever 562 and roller lever 504, a controllable damping device 6 is assigned to the latter.

The damping device 6 can in principle be designed differently. According to FIG. 16, a plate spring 60 is arranged on the pivot axis 540, with the aid of which the roller lever 504 (or possibly the switch lever 506 - see FIGS. 8 and 12) is axially immovably mounted on the pivot bearing 54. A rod 61, which carries a fork 610, is provided, movable parallel to the pivot axis 540. The fork 610 engages around the pivot axis 540 formed by a bolt and exerts a pressure on the plate spring 60, which is supported on the roller lever 504 (or on the switching lever 506), from its position in relation to the roller lever 504 (or the switching lever 506 ) depends. The greater the pressure, the greater the preload of the plate spring 60 and thus the greater the damping effect of the damping device 6.

The function of the damping device 6 is described below. In principle, such a damping device 6 has the task of making the roller lever 504 or the changeover lever 506 sluggish in order to prevent a slight imbalance in the spinning rotor 100 from increasing wear of the roller lever 504 or of the switching lever 506 and its storage. On the other hand, a damping device 6, if controllable, offers the possibility of being able to control the run-up behavior of the spinning rotor 100. If the roller lever 504 or the changeover lever 506 is released by the brake lever 562, it only follows the force exerted by the tension spring 550 (or by another suitable elastic element) depending on the preload of the plate spring 60. The stronger the pretension of the plate spring 60, the longer it takes until the roller lever 504 or the changeover lever 506 brings the control roller 50 into full contact with the drive belt 17. It is thus possible, by moving the fork 610 parallel to the pivot axis 540 of the roller lever 504 or the changeover lever 506, to control the response speed with which the roller lever 504 or the changeover lever 506 responds to a release by the brake lever 562.

The loading element, which is designed as a fork 610 in the exemplary embodiment described above, can naturally take different forms. It is conceivable to preload the plate spring 60 with the aid of a stepping motor (not shown).

The damping element 6 can also be designed differently, for example as a controllable bypass line (not shown) of a hydraulic or pneumatic piston, the damping depending on the degree of opening of this bypass line.

A similar design, in which the speed n _{R of} the spinning rotor 100 is controlled with the aid of a switch lever 506, is explained below with reference to FIG. 8. The switch lever 506 is in turn centered on a pivot bearing 54. A pressure spring 55 is associated with the arm 500 of the control lever, which carries the control roller 50, and is supported in a suitable manner on the frame 191 of the open-end spinning machine 1. The compression spring 55 thus has the effect that, as a rule, the control roller 50 holds the drive belt 17 in contact with the shaft 103 of the spinning rotor 100.

The arm 500 of the switch lever 506 carries a stop 501 against which a stop 560 of a brake lever 56 can be brought into contact. The brake lever 56 is arranged together with the control roller 50 on a common axis 502. At its free end, the brake lever 56 is connected to a control link 57.

Between its two ends, the brake lever 56 carries a brake with a brake pad 561, which is lifted off the shaft 103 of the spinning rotor 100 in the position of the brake lever 56 shown. However, if the control linkage 57 is pulled down in FIG. 8, the brake pad 561 comes to rest against the shaft 103, so that the spinning rotor 100 is braked. In addition, when the movement of the control rod 57 continues, the control roller 50 is lifted off the drive belt 17, so that the drive belt 17 is lifted off the shaft 103 of the spinning rotor 100 by the support rollers 19 and 190 (see FIG. 12). When the control linkage 57 returns to the position shown, the compression spring 55 brings the control roller 50 back into the position shown, in which the drive belt comes to rest against the shaft 103 of the spinning rotor 100. If the control link 57 is raised slightly, the stop 560 of the brake lever 56 comes to rest against the stop 501 of the switch lever 506. If this stroke movement of the control linkage 57 continues slightly, the contact pressure between the control roller 50 and the drive belt 17 and thus also between the drive belt 17 and the shaft 103 of the spinning rotor 100 is reduced so that the slip increases. As this stroke movement of the control rod 57 continues, the brake lever 56 pivots the switch lever 506 further via its stop 560, so that the control roller 51 brings the drive belt into contact with the shaft 103 of the spinning rotor 100.

It therefore depends on how large the lifting movement of the control linkage 57 is, in order to achieve a precisely defined slip between the drive belt 17, which is still driven at an unchanged speed, and the shaft 103 of the spinning rotor 100, or between the drive belt 18, which is also driven unchanged at a constant speed, and the shaft 103 to achieve the spinning rotor 100. Accurate speed control of the spinning rotor 100 is thus possible by appropriately lifting the control rod 57. The acceleration of the spinning rotor 100 is controlled by a corresponding control of the slip between the drive belt 17 driven at a higher speed and the shaft 103, while the speed reduction is controlled by controlling the slip between the drive belt 18 driven at a lower speed and the shaft 103 of the spinning rotor 100 .

FIG. 9 shows the device for controlling the spinning rotor 100 shown in FIG. 8 in a side view. The spinning rotor 100 is included With the aid of support disks 104, only one of which is shown in FIG. 9, and an axial / radial bearing 105. The control linkage 57 has a two-armed lever 570 which is pivotable about a bearing 571. At the free end, the lever has a roller 572, which is surrounded by a fork 58. The fork 58 sits at the end of an angle lever 580, the free end 581 of which is mounted in a slot in the cover 13. In addition to position I, which represents the spinning position and in which it is shown, the free end can also assume a position II in which the brake pad 561 (FIG. 8) is brought into contact with the shaft 103 of the spinning rotor 100. Furthermore, the free end of the angle lever 580 can also assume a position III in which the roller 51 presses the drive belt 18 against the shaft 103 of the spinning rotor 100. The lever movement is controlled by a drive device 24 which can be advanced to the angle lever 580, which is arranged on the maintenance device 2 and is controlled by the control device 20.

Fig. 9 clearly shows that by shifting the position III, the indentation of the control roller 50 and 51 relative to the drive belt 17 and 18 can be changed. In order to be able to determine a precise stroke path in relation to the angle lever 580, the drive device 24 can be assigned a stop (not shown) on the cover 13, against which a counter-stop is supported during its actuating movement, said stop being arranged with the drive device 24 or one arranged thereon Actuator is connected.

Such an adjustable stop does not need to cooperate with the drive device 24, but can also - depending on the design of the belt pressing device - the switch lever 506 (see serving as setting device 59, 590 serving stops in Fig. 12), its control linkage 57 or else Angle lever 580 must be assigned. Depending on the design of the belt pressing device, the stop (not shown) can also determine either the maximum or the minimum contact pressure. The setting can be done manually or - to adapt to different desired rotor speed - make changes automatically, as will be described in more detail later.

The switch lever 506 with the associated control elements thus forms a belt pressing device 5, with which the contact pressure between the drive belt 17 or 18 and the shaft 103 of the spinning rotor 100 can be controlled in the desired manner to control the speed n _{R of} the spinning rotor. In the case of a two-armed switch lever 506, each or even only one of the arms 500 and 503 can be brought into effect as part of the belt pressing device.

If very rapid reductions in the rotor speed are required, reducing the speed n _R only with the aid of the drive belt 18 can be too slow. According to the modification shown in FIG. 13 of the embodiments of the device for controlling the rotational speed n _{R of} the spinning rotor 100 previously described with reference to FIGS. 8 and 9, separate control linkages 573 for the changeover lever 506 and 574 for the brake lever 56 are therefore provided, so that the braking effect the brake can be controlled precisely. This 13 is similar to the control of the belt pressing device in the device shown in FIG. For this purpose, the control linkage 573 connects the arm 503 of the switching lever 506, which carries the control roller 51, to the lever 570, which was previously explained with the aid of FIG. 9. The control linkage 574 is connected to an angle lever 575, which is pivotably supported by means of a bearing 576. The angle lever 575 is arranged in a slot next to the angle lever 580 in the top 13. The arrangement of the changeover lever 506 and the parts directly or indirectly assigned to it were shown rotated by 90 ° in FIG. 13 only for illustrative reasons. The angle lever 575 also does not correspond to the actual installation conditions.

By acting on the brake shown in FIG. 13, the speed n _{R of} the spinning rotor 100 can thus be reduced, possibly also with a simultaneous reduction in the speed n _{R of} the spinning rotor 100 by controlling the slip between the drive belt 17 or 18 and the shaft 103 A strong speed reduction can be particularly advantageous in the first phase of a multi-phase speed reduction.

A further modification of a device with the aid of which the braking action is precisely controlled will now be explained using the example of the device shown in FIG. 16. As far as the damping device 6 is concerned, this device has already been discussed.

15, in which the control linkage 57 is connected directly to the brake lever 562, the brake lever 562 has a guide 565 through which a bolt of the control linkage 57 is passed. On the side facing the roller lever 504 or the changeover lever 506, a stop 577 is axially immovably arranged on this bolt of the control linkage 57 in order to bring about an inevitable entrainment of the brake lever 562 when moving away from the roller lever 504 or changeover lever 506 - ie in the lifting direction . On the side facing away from the roller lever 504 or the changeover lever 506, the bolt of the shift linkage 57 likewise carries a stop 578, which is however arranged at a distance from the guide 565. A compression spring 579 is provided between this guide 565 and the stop 578.

If the shift linkage 57 is now actuated in such a way that the brake lever 562 with its brake lining 561 comes to rest against the shaft 103 of the spinning rotor 100 - that is, the brake lever 562 is moved in the braking direction - it is carried along only via the compression spring 579, which initially is relaxed or has only a slight bias. If the brake pad 561 thus comes to rest against the shaft 103, the brake acts only with very little force, since the further stroke of the control linkage 57 is absorbed by the compression spring 579. Here, the preload of this compression spring 579 increases, so that the braking force that acts also increases accordingly over time. The braking effect and thus also the braking behavior of the spinning rotor 100 can thus be controlled by appropriate selection of the stroke.

If the control link 57 is actuated in the opposite direction in order to move the brake lever 562 in the lifting direction, the braking force is first reduced without the brake lever 562 being moved until the compression spring 579 has reached its relaxed starting position again. At this moment, the stop 577 comes to rest against the guide 565 and now takes the brake lever 562 with it, so that the brake pad 561 is lifted off the shaft 103.

The device described can also be combined with a damping device 6 (according to FIG. 16) or a tension spring 551 between roller lever 504 or switch lever 5 on the one hand and brake lever 562 on the other hand, so that both the braking and the starting behavior of the spinning rotor 100 are precisely controlled can.

If, in such a device combined with a damping device 6, the brake lever 562 - after the shaft 103 is released by the brake pad 561 - is moved further in the lifting direction, then the roller lever 504 or the changeover lever 506 follows this movement only after a delay, depending on the pretensioning of the damping device 6 , so that the contact pressure caused by the control roller 50 between the drive belt 17 and the shaft 103 increases only gradually. The same is the case if, instead of a damping device 6, a tension spring 551 or the like. is provided, this contact pressure then depending on the relative position of the brake lever 562 relative to the roller lever 504 or the switch lever 506.

The described method and also the described device can be modified in a variety of ways within the scope of the present invention, for example by combining individual features by equivalents or by another combination. The piecing process and thus also the times to be observed, speed deceleration and acceleration as well as the acceleration of the thread take-off can be controlled in various ways, for example by specifying or setting appropriate times. However, due to different factors such as manufacturing tolerances, tolerances due to wear, different slippage, etc., certain deviations in the speed behavior of the driven elements can occur. In order to reduce this to a minimum, the rotor speed can be controlled depending on the thread take-off speed. It can be advantageous if the rotor speed is reduced to the same percentage of the thread take-off speed (speed V _A ) and then accelerated again to achieve a constant rotation, which corresponds to that during the spinning conditions, in synchronism with the thread take-up speed. 11 that the speed V _{A of} the device, by means of which the thread 30 is drawn off from the open-end spinning device 10 after piecing, is monitored.

With the help of this device, it is possible to monitor the withdrawal speed of the thread 30.

For this purpose, the control device 4 (generally with the control device 20 interposed on the maintenance device 2 - See Fig. 10) connected to the drive motor 212 for the auxiliary drive roller 211.

Such a device is shown in FIG. 11, which is directly controlled without the interposition of a service vehicle 2, as is e.g. is or can be the case with individual test devices.

11, the control device 4 is connected via a line 41 to the drive motor 212 in order to give the latter the control pulses required for starting and starting up. The speed of the drive motor 212 is scanned via a tachometer generator 213, which scans, for example, the extended axis of the drive motor 212. On this axis sits a drive wheel 214, which is connected via a chain or a belt 215 to a further drive wheel 216, on the axis of which the auxiliary drive roller 211 is arranged.

The tachometer generator 213 is connected via a line 42 to a means 43 of the control device 4, which compares the electrical quantity generated with the aid of the tachometer generator with the quantity that the auxiliary drive roller 211 would reach after reaching its desired rotational speed, and leads therefrom for the value determined by the tachometer generator 213 from the corresponding percentage value.

Similarly, the shaft 103 of the spinning rotor 100 is assigned a tachometer generator 106, which is connected via a line 44 to a means 45 of the control device 4, which likewise how the means 43 calculates the percentage value of the current speed n _{R of} the spinning rotor 100 by comparing the actual speed with the target speed. The percentage converted measurement values of the thread take-off speed and the rotor speed by the two means 43 and 45 for converting the measurement values into percentage values are supplied via lines 430 and 450 comparison means 46, where it is checked whether the two percentage values are in agreement. The comparison means are connected via a line 481 to the input of a comparison device 48, the other input of which is connected to the control device 4 via a line 480.

In the exemplary embodiment shown, the drive of the spinning rotor 100 is designed as an individual drive motor 107, which is connected to the comparison device 48 via a line 482.

The control device 4 gives control impulses to the drive motor 212 via the line 41 during the spinning, which then drives the spool 162 accordingly via the auxiliary drive roller 211 and with the aid of this spool 162 pulls the thread 30 out of the spinning rotor 100. The draw-off roller pair 14 is open here, so that the piecing draw-off takes place solely through the coil 162. During the run-up of the drive motor 212, the tachometer generator 213 supplies corresponding pulses via the line 42 to the means 43 of the control device 4, which convert the measured values obtained from the tachometer generator 213 into percentage values. The preset full thread take-off speed serves as the reference value.

At a predetermined point in time, possibly even before the return R _{F of} the thread end 300 into the spinning rotor 100, the reduction in the rotational speed n _{R of} the spinning rotor is started. As long as the spinning rotor 100 has not yet reached the same percentage value as the thread take-off, the control device 4 via the comparison device 48 prevents a control pulse output via a line 482 to the drive of the spinning rotor 100, for example a single drive motor 107. However, if the speed n _{R of} the spinning rotor 100 reaches the same percentage value as the speed V _{A of} the thread take-off, then the comparison means 46 sends a corresponding pulse to the means 48 via the line 481. This has the effect that the speed reduction that was previously achieved via the Line 480 was initiated, is terminated by giving a corresponding control pulse to the individual drive motor 107 via line 482. The rotor is now started up in the manner specified by the control device 4.

When the thread take-off has reached the desired production speed, the thread 30 is brought under the lifted take-off roller 141 and then the pull-off roller 141 is lowered in a known manner onto the driven take-off roller 140 or the thread 30 is inserted into the pair of draw-off rollers 14 so that the take-off is subsequently carried out done by this pair of draw rollers 14. The auxiliary drive roller 211 is lifted off the spool 162, which is now brought into contact with the driven winding roller 160.

The described method of piecing the thread 30 at a greater distance with the aid of a spool 162 instead of With the help of the take-off roller pair 14, after the production take-off speed has been reached - which is in principle quite possible - there is also the advantage that the real rotation can be distributed over a larger thread length in the piecing phase. Thus, when the length section 330 is pulled off, the advantage of the high false twist can be used on the one hand, without the thread 30 reaching the spool 162 therefore having to have an overturn.

The speeds or speeds can be monitored directly or indirectly. In the exemplary embodiment described above, the thread take-off speed was indirectly monitored directly via the speed of the drive motor 212 and the speed n _{R of} the spinning rotor 100.

The described device for scanning the rotor speed (tachogenerator 106) can also be used when the change from speed reduction to speed acceleration depending on reaching a predetermined minimum value of the speed n _{R of} the spinning rotor 100 is to take place, without any adjustment to the Startup of the speed V _{A of} the thread take-off must be provided.

In the case of the single drive motor 107 described, the means for reducing the speed n _{R of} the spinning rotor 100 can be formed by the control device 20, which initiates and controls, for example, the speed reduction. The means for re-acceleration can be formed jointly by the control devices 4 and 20 by the control device 4 according to the address Chen of the tachometer generator 106 initiates the rotor run-up, which is then controlled by the control device 4. The means for appending the rotor speed to the production speed is then formed by the control device 4 alone, which prevents further acceleration when the predetermined operating or production speed is reached.

Alternatively, if the acceleration of the spinning rotor 100 following this speed reduction is to be adapted to the acceleration of the thread take-off, control impulses are sent to the individual drive motor 107 via line 47 after the reduction in the rotor speed has ended, which cause the spinning rotor 100 to run up adapt to the acceleration of the thread take-off, ie regulate so that this run-up is proportional to the run-up of the thread take-off, ie in such a way that the rotor run-up - in percent - coincides with the run-up of the speed V _{A of} the thread take-off.

In the method described last, the thread take-off speed is monitored for the entire duration of its acceleration. The rotor speed change takes place from the point in time at which the speed n _{R of} the spinning rotor 100 reaches the same percentage of the operating speed as the thread take-off until the point in time at which the rotor speed and thread take-off - together - reach the full production values, synchronously with the increase in the thread take-off speed V _A.

To control the rotor run-up, the control device 4 can also be assigned a generator (not shown) which is used for control tion of the rotor run-up generates corresponding electrical values that can be adapted to the thread run-up, if desired.

In the variants of the method described so far, it was assumed that the thread take-off is accelerated according to a defined curve. This curve can be preset on the control device 20 of the maintenance device 2 or - if no maintenance device 2 is provided - on the control device 4.

However, it is also possible to have this setting carried out automatically. In order to make this clear, a description will be given below of what happens when the fiber sliver 3 is stopped by actuation of the electromagnet 114 while the opening roller 121 is still driven. The clamping line K is shown in FIGS 11 the sliver 3 is held clamped. In the device shown in FIG. 10, the delivery roller 110 for stopping the sliver 3 is not controlled. Instead, the upper end is brought into contact with the feed trough 111 by pivoting the clamping lever 113, the sliver 3 being clamped between the clamping lever 113 and the feed trough 111 and the feed trough 111 being pivoted away from the delivery roller 110. The clamping line K is formed here by the line on which the clamping lever 113 presses the sliver 3 against the feed trough 111.

Alternatively, however, the electromagnet 114 and the clamping lever 113 can also be omitted and instead the delivery roller 110 be assigned a clutch, not shown. In this case, the clamping line K is formed by the line in which the feed trough 110 presses the sliver 3 against the delivery roller 110.

6a) to 6c), a line A is also shown, which symbolizes the boundary of the working area of the opening roller 121 (see FIG. 10).

During the normal spinning process, in which delivery device 11 and opening roller 121 run, the latter acts - from the right in FIGS. 6a) to 6c) up to line A on the front end of the sliver 3, the so-called fiber beard 34, and combs out out fibers 31 which are then fed through the fiber feed channel 122 to the spinning rotor 100. As FIG. 6 a) shows, the fibers 31 partially extend far beyond the line A into the working area of the opening roller 121, while other fibers 31 only extend into the area between the clamping line K and the line A.

The fiber beard 34 looks similar with a short downtime of the delivery device 11.

If the delivery device 11 is idle for a longer period of time and the opening roller 121 continues to run, the latter continues to comb fibers 31 out of the fiber beard 34. The fiber beard then only has a few fibers 31 which extend beyond line A (FIG. 6b)). The longer the standstill time of the delivery device 11 (always with the opening roller 121 continuing to run), the shorter the fiber beard 34 until there are no longer fibers 31 during a long standstill time protrude into the working area of the opening roller 121, ie until the longest fibers 31 extend from the clamping line K at most to the line A (FIG. 6a)).

As will now be explained in more detail with reference to FIG. 7, these different states of the fiber beard 34 result in a different startup behavior of the feed. 7 shows the time t on the abscissa, while the ordinate represents the speed in percent. 7a) to 7c) show different downtimes t _Sa , t _Sb and t _Sc which begin with the occurrence of a thread break BF and are ended by switching on the delivery device 11 again.

If the delivery device 11 is started up again after a downtime at the time t _L (FIG. 7), the sliver 3 is fed to the opening roller 121. With a very short downtime t _Sa (FIG. 7a) of the delivery device 11 (compare with FIG. 6a)), the fiber beard 34 has practically the same shape as during the spinning process itself. With a slight delay t _Va , which is due to the time required to generate a fiber stream again between the delivery device 11 and the spinning rotor 100, the fiber feed, ie the fiber stream arriving on the fiber collecting surface 102 of the spinning rotor 100, reaches its full again Value (100% - see ramp-up time t _Va ). This is shown in Fig. 7a), where the fiber feed F is shown as a strong, uninterrupted line.

If the downtime t _{Sb was} somewhat longer (FIG. 7b)), there is initially a weakened fiber beard 34 in the region of the Dissolving roller 121. After the delivery device 11 has been released, only a somewhat lean fiber stream initially reaches the fiber collecting surface 102, this also starting with a somewhat greater delay t _Vb in comparison to the fiber flow according to FIG. 7a). Even if more and more fibers 31 reach the working area of the opening roller 121 during the subsequent transport of the sliver 3, the fiber supply does not suddenly increase to its full value (100%), but takes a certain time for this. The run-up time t _Sb for a fiber beard 34 according to FIG. 6b) is thus longer than for a fiber beard 34 according to FIG. 6a).

The situation becomes even more extreme with a fiber beard 34 which has been exposed to the action of the opening roller 121 for a very long time when the delivery device 11 has been stopped. With a very long standstill time t _Sc , the fiber beard 34 must first be brought over the line A into the working or effective range of the opening roller 121. Since the fiber beard 34 according to FIG. 6c was combed out considerably more than the fiber beard 34 according to FIG. 6b, it also takes longer to start the fiber flow (see delay t _Vc ). The ramp-up time t _Sc is also significantly longer.

As is clear from Fig. 7, the thread draw (see speed V _A ) must be adapted to the effective fiber feed F. It follows from this that the control of the speed n _{R of} the spinning rotor 100 must also be controlled differently depending on the downtime t _Sa , t _Sb or t _Sc . This affects both the reduction in the speed n _R and the later re-acceleration of the rotor speed.

The duration of the downtime is determined in the control device 4 from the time at which the thread monitor 15 (see FIG. 10) responds and the time at which the control device 4 gives a pulse to the control device 20 after the maintenance device 2 on the has reached the relevant spinning position, so that the maintenance device 2 now begins the piecing process. Alternatively, of course, the control device 20 of the maintenance device 2 can also give a corresponding impulse to the control device 4, by means of which the end time of the downtime is determined, since the time t _L for switching on the delivery device 11 at a predetermined time interval of this switch-on time of the piecing device.

The switching on and acceleration of the thread take-off are then controlled in accordance with the measured time - and correspondingly also the speed n _{R of} the spinning rotor 100, the speed control not necessarily having to be synchronous with the control of the thread take-off speed, if not the rotation in the thread 30, but the thread tension even after deduction of the piecing 32 from the spinning rotor 100 is still of particular importance. The longer the idle time t _Sa , t _Sb or t _Sc , the later the fiber flow F starts in the spinning rotor and the later the thread take-off must also start. The run-up curve of the fiber flow is also flatter with a longer standstill time, so that the run-up curve of the thread take-off must also be flatter.

The determination of the fiber beard does not need to be done indirectly by measuring the downtime, but can also be done directly, for example by measuring the air resistance of the fiber beard. The corresponding device, with which the combed state of the fiber beard is determined, is in a suitable tax connection with the control device 4 and / or 20, so that it can then control the thread take-off and the rotor speed in an adapted manner.

As the above description shows, the spinning rotor 100 can be controlled in its speed n _R in various ways. In this way, the slip of its drive (see FIGS. 8, 9, 10 and 12 - possibly also by interposing a torque or slip clutch) can be controlled. The spinning rotor 100 can also be braked with the aid of a controllable brake (see FIGS. 8 and 13) while the central drive continues to run or can be accelerated again in a controlled manner. It is also possible to provide a single drive motor 107 (see FIG. 11) for controlling the spinning rotor 100.

If an exact adaptation of the speed change (speed reduction or acceleration) of the spinning rotor 100 to the speed V _{A of} the thread take-off is desired, the speed of the spinning rotor 100 can also be monitored for a slip control for the control of the speed behavior.

It is also possible to provide a main drive which drives the spinning rotors 100 of a plurality of adjacent spinning stations at production speed, while an auxiliary drive is provided for thread break removal, with which the spinning rotor 100 always only has a single spinning station for the duration of the piecing is coupled. The two drives can be designed as belts or shafts etc.

The two drives are connected to the control device 4 to control the coupling and uncoupling. The speed of the auxiliary drive is controlled by the control device 4 during piecing in such a way that the spinning rotor 100 is first reduced in its speed n _R and is accelerated again to the full production speed at the desired point in time.

If the time control of the rotor speed is not carried out exactly, a thread break does not necessarily have to occur in spite of the predetermined tolerances of the thread tension S _{F being} exceeded, even though the risk of thread breakage is great. In order to reduce this risk for future piecing processes, the thread tension S _F in the spun thread 30 can be monitored during the piecing, which can be done with the aid of the thread monitor 15 designed as a thread tension monitor or an additional thread tension monitor (not shown). If the determined thread tension deviates from the target tension more than is considered tolerable, the control device 4 is sent a corresponding signal. This has the effect that the speed n _{R of} the spinning rotor is controlled accordingly in the subsequent piecing process, for example according to FIG. 5, so that the thread tension deviations become smaller or disappear.

Depending on the programming, it can also be caused that the piecing process just monitored is repeated immediately or that The newly set speed control only comes into play for the correction of an unprovoked thread break.

A value can be manually entered into the control device 4 as a reference value. However, the control device 4 can also contain means which measures the thread tension during normal spinning operation and stores the average value of the measured thread tension values as a reference value for the comparison of the thread tensions occurring during piecing.

Such control of the rotor speed change can be carried out electronically (e.g. in the case of a single drive motor 107) or mechanically with the aid of a stop (not shown) (for example with the aid of a belt pressing device).

Claims (40)

1. A method for piecing a thread on an open-end spinning device working with a spinning rotor, in which a thread end is delivered at a starting speed of the spinning rotor on its fiber collecting surface, connected there with the fibers of a fiber ring and then, with continuous integration, fibers newly fed into the spinning rotor as Continuous thread is withdrawn from the spinning rotor, characterized in that the rotor speed is brought up from the piecing speed immediately after piecing to a speed which is lower than the piecing speed and then increased again to the production speed. 2. The method according to claim 1, characterized in that the reduction of the rotor speed is ended as a function of time. 3. The method according to claim 1, characterized in that the reduction of the rotor speed is ended when a predetermined minimum rotor speed is reached. 4. The method according to one or more of claims 1 to 3, characterized in that the preparation speed before the return of the thread end on the fiber collecting surface is kept temporarily constant and the rotor speed is only reduced in the time between the return of the thread end and the start of the thread take-off. 5. The method according to one or more of claims 1 to 4, characterized in that the rotor speed is accelerated from standstill to a speed above the start-up speed and is brought from this speed to the start-up speed. 6. The method according to one or more of claims 1 to 5, characterized in that the reduction of the rotor speed begins at a speed above the preparation speed and is continued during the application process. 7. The method according to one or more of claims 1 to 6, characterized in that the rotor speed after the removal of the mass-increasing part of the fiber ring is further reduced until by the accelerating thread take-off speed and the decreasing rotor speed have reached a certain desired ratio to one another, whereupon the rotor speed and the thread take-off speed are accelerated to the production speed. 8. The method according to claim 7, characterized in that the certain desired ratio is the same as at production speed and from the moment at which this ratio is achieved by the reducing rotor speed and the accelerating thread take-off speed, even during the subsequent acceleration of the rotor speed is maintained. 9. The method according to claim 5, characterized in that the thread take-off speed is monitored and when the rotor speed reaches the same percentage value of the production value as the thread take-off speed, the reduction in the rotor speed is ended. 10. The method according to one or more of claims 1 to 8, characterized in that in order to change the rotor speed, the slip between the spinning rotor and driving means which continue to run at unchanged speed is changed. 11. The method according to one or more of claims 1 to 9, characterized in that the spinning rotor is brought into drive connection to reduce its speed with lower speed drive means and to increase its speed with higher speed drive means. 12. The method according to one or more of claims 1 to 10, characterized in that the reduction of the rotor speed is carried out in two phases, the first phase essentially both on the propagation of rotation in the fiber ring and on the desired thread tension and the second phase for limitation the thread tension tolerances that occur are matched to the thread tension. 13. The method according to claim 11, characterized in that the reduction of the rotor speed in the first phase is effected or supported by the effect of a brake. 14. The method according to one or more of claims 1 to 8, characterized in that for changing the rotor speed of the spinning rotor is separated from drive means running at production speed and connected to auxiliary drive means which initially slows down in speed according to the desired speed profile of the spinning rotor during piecing and later accelerated again until the production speed is reached, whereupon the spinning rotor is separated from the auxiliary drive means and connected to the drive means running at production speed. 15. The method according to any one of claims 1 to 13, in which a sliver, from which the fibers feeding the spinning rotor are combed, remains at least temporarily exposed to the action of a rotating opening roller even when the spinning process is interrupted, characterized in that the state of the fiber beard, which was exposed to the effect of the rotating opening roller during an interrupted spinning process, is determined at the start of the piecing process and the acceleration of the thread take-off speed and the rotor speed takes place from the determined fiber beard state. 16. The method according to one or more of claims 1 to 14, characterized in that the thread tension in the drawn thread is monitored during piecing and, if a predetermined deviation from the thread tension occurring during normal production is exceeded during the next piecing process, the reduction of the rotor speed corresponding to the deviation is corrected. 17. The method according to one or more of claims 1 to 15, characterized in that during the time during which the thread draw-off speed has not yet reached its production value, the thread is given the draw-off movement at a greater distance from the spinning rotor than after reaching the production value. 18. Device for piecing a thread in an open-end spinning device, with a drivable spinning rotor having a fiber collecting surface, a device for feeding fibers onto the fiber collecting surface, means for returning a thread end to the fiber collecting surface, means for pulling off the spun thread and means for Changing the speed of the spinning rotor to carry out the method according to one or more of claims 1 to 16, characterized net by means of reducing the rotor speed from the starting speed to a lower value, means for re-accelerating the rotor speed after a desired minimum value or a time provided for this has been reached, and means for appending the ramping rotor speed to the desired production speed. 19. The apparatus according to claim 17, characterized by a time control means (23) having control device (4, 20). 20. The apparatus according to claim 18, characterized in that the timing control means (23) are associated with setting means (230, 231) for determining the duration during which the rotor speed is reduced. 21. The apparatus according to claim 17, characterized by means (106) for monitoring the rotor speed or the rotor speed proportional values. 22. The apparatus according to claim 20, characterized in that in addition to the means (106) for monitoring the rotor speed or values proportional to this speed monitoring means (213) for monitoring the thread take-off speed or values proportional to this speed, further means (43, 45) for converting the Measured values in percentages of the respective full production values as well as comparison means (46) are provided for comparing the percentages of the thread take-off speed and rotor speed and for triggering a Switching impulse when matching percentages are reached to end the reduction of the rotor speed. 23. The apparatus according to claim 21, characterized in that the monitoring means (213, 106) with control means (4) for generating a rotor speed proportional to the thread take-off speed are connected. 24. The device according to one or more of claims 17 to 22, with a belt drive for the spinning rotor, which is mounted with the aid of a shaft and can be driven via this shaft, the belt being liftable from the rotor shaft, characterized by a belt pressing device (5) which is used to change the contact pressure between the drive belt (17, 18) and the rotor shaft (103) is connected to the control device (4, 20) in terms of control. 25. The device according to one or more of claims 17 to 23, with two drive belts which can be driven at different speeds, for the selection of which a two-armed switch lever is provided for selectively driving the spinning rotor, one arm of which drives the spinning rotor by the belt which is driven at a higher speed and whose other arm causes the spinning rotor to be driven by the other belt, characterized in that at least the arm (503) of the two-armed switching lever (5) which drives the spinning rotor (100) at a lower speed is designed as a belt pressing device. 26. The apparatus of claim 23 or 24, characterized in that the belt pressing device (5) is assigned an adjusting device (59, 590) for determining the maximum or minimum contact pressure between the drive belt and the rotor shaft (103). 27. The device according to one or more of claims 23 to 25, with a maintenance device carrying the control device, movable along a plurality of similar open-end spinning devices, characterized in that the belt pressing device (5) is connected to a control lever (580), which a actuating element (24) of the maintenance device (2) controllable from the control device (20) is deliverable. 28. The apparatus according to claim 26, characterized in that the open-end spinning device (10) has a stop to limit the feed path of the actuating element (24). 29. Device for spinning a thread in an open-end spinning device, with a drivable spinning rotor having a fiber collecting surface, a device for feeding fibers onto the fiber collecting surface, means for returning a thread end to the fiber collecting surface, means for pulling off the spun thread and means for Changing the speed of the spinning rotor, in particular for carrying out the method according to one or more of claims 1 to 16, characterized in that a belt (17, 18) for driving the spinning rod mounted by means of a shaft (103) tors (100) and a belt pressure device (5) are provided, which has a belt pressure roller (50) carrying roller lever (504), which by means of a first elastic element (550) with its belt pressure roller (50) for abutment on the belt (17, 18) and to which a brake lever (562), which can be adjusted to the rotor shaft (103), is assigned, which, apart from a braking position, can be brought into various relative positions relative to the roller lever (504) such that the brake lever (562) and the roller lever (504) cooperating stops (505, 564) are assigned, by means of which the roller lever (504) can be lifted from the belt (17, 18) by the belt pressure roller (50) when the brake lever (562) moves into its braking position, so that the brake lever (562) and the roller lever (504) are connected to one another via a weaker elastic element (551) compared to the first elastic element (550), with the aid of which by changing the relative position between the brake lever (562) and roller lever (504) the belt pressing force caused by the first elastic element (550) can be reduced. 30. The device according to claim 28, characterized in that the roller lever (504) has two arms (500, 503), one arm (500) of which supports the belt pressure roller (50) and is acted upon by the second elastic element (551), while the arm (503) facing away from the belt pressure roller (50) can be acted upon by the first elastic element (550). 31. Device for spinning a thread in an open-end spinning device, with a drivable spinning rotor having a fiber collecting surface, a device for feeding fibers onto the fiber collecting surface, means for returning a thread end to the fiber collecting surface, means for pulling off the spun thread and means for Changing the speed of the spinning rotor, in particular for carrying out the method according to one or more of claims 1 to 16, characterized by a belt (17, 18) for driving the spinning rotor (100) mounted by means of a shaft (103) and a belt pressing device (5) which has a roller lever (504) carrying a belt pressure roller (50), which can be lifted off the rotor shaft (103) by a brake lever (562) and to which a controllable damping device (6) is assigned. 32. Apparatus according to claim 30, characterized in that the damping device (6) as a on the pivot axis (540) of the roller lever (504) mounted plate spring (60) is formed, which is a parallel to the pivot axis (540) adjustable loading element (61, 610 ) assigned. 33. Device according to one or more of claims 23 to 31, with a maintenance device carrying the control device, movable along a plurality of similar open-end spinning devices, characterized in that the belt pressing device (5) each open-end spinning device (10) is assigned its own actuating device, via which the belt pressing device (5) is connected to the control device (4). 34. Device according to one or more of claims 17 to 32, with a brake which can be brought into action on the spinning rotor, characterized in that the brake (561) is designed as a brake with controllable braking action. 35. Apparatus according to claim 33, characterized by a brake lever (562) which can be actuated in the braking direction via an elastic element (579) and in the lifting direction via a rigid stop (577) by a control element (57). 36. Device according to one or more of claims 17 to 22, with an individual drive motor for the spinning rotor, characterized in that the control device (4) contains a generator for generating electrical values, by means of which the speed (n _R ) of the spinning rotor (100 ) is controlled. 37. Device according to one or more of claims 17 to 22, with two drive means which can optionally be brought into action with the spinning rotor, of which the one serves to simultaneously drive a plurality of spinning rotors, while the others only serve to drive a single spinning rotor in each case, thereby characterized that the to drive a single spinning rotor (100) provided drive means (107) in terms of control connected to the control device (4) and can be controlled by this. 38. Device according to one or more of claims 17 to 36, characterized in that the control device (4, 20) is connected to a device which detaches the condition of the fiber beard at the time of return of the thread end (300) to the fiber collecting surface (102) determined and controls the thread take-off and the rotor speed depending on the combed condition. 39. Device according to one or more of claims 17 to 22, characterized by a thread tension monitor (15) which is connected to the control device (4) in terms of control, further by means for comparing the measured thread tension with a predetermined reference tension and by means for changing the data stored in the control device (4) in such a way that the rotor speed is reduced in the future in such a way that thread tension deviations are reduced. 40. Apparatus according to claim 38, characterized in that the control device (4) contains means which store the average value of the thread tension in undisturbed production as a reference value.

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