The invention also relates to a device for carrying out said method on an open- end spinning machine each operating unit of which contains a spinning unit with a sliver feed device, a spinning rotor, and a yarn delivery tube over which, in the yarn travel path, there is situated a draw-off mechanism comprising a draw-off roller and a pressure roller seated on a swinging pressure lever, a yarn distribution mechanism and a yarn winding-up mechanism holding in its arms a bobbin, and comprising also a control unit connected with the sliver feed device.

Background Art The spinning unit of a rotor spinning machine comprises a textile fibre sliver feed device followed by a fibre singling out device out of which the singled out fibres are by means of underpressure led into the inner space of the spinning rotor and there collected on a collecting groove and due to the spinning rotor rotation transformed into a fibre band. The yarn in process of production is led from the spinning rotor by an outlet tube and is drawn off by draw-off rollers and wound on a bobbin. The presence of the yarn between the outlet tube and the winding device is monitored by a sensing device adapted to send out in case of a yarn rupture a signal intended to stop at least the sliver feed device.

The resumption of the spinning process, called yarn spinning-in, comprises the steps of introducing the yarn end into the outlet tube of the spinning unit in the direction opposite to that of the yarn delivery into the outlet tube of the spinning unit and of letting it come to lie on the collecting groove of the rotating spinning rotor into which prior to this the feed of singled-out fibres has been resumed and a fibre band has been formed on the collecting groove of the.spinning rotor. After connecting the yarn end to the fibre band, the draw-off motion of the yarn is resumed and yarn is produced from said fibre band.

The spinning-in can be carried out either manually or automatically by one of the well-known devices created for this purpose.

When spinning-in manually after a yarn rupture, the operator first tilts the bobbin out of contact with its drive roller, detects the yarn end on the bobbin, winds off the required yarn length, and introduces then the yarn end into the outlet tube of the spinning unit into which the yarn end is sucked by the underpressure existing in the spinning rotor. Having introduced the yarn end into the outlet tube of the spinning unit, the operator tilts the bobbin in the winding device to its operating position in which it is in contact with the drive roller. During this movement, the operator resumes the feed of singled-out fibres into the spinning rotor.

As soon as the yarn end reaches the collecting groove of the spinning rotor the fibres of the fibre band begin to join it, the bobbin, now in contact with its drive roller, begins to rotate, and the yarn newly in process of production begins to be drawn-off from the spinning rotor and wound on the bobbin. The operator cannot influence the time interval during which the renewed fibre band is in connection with the yarn end. In a subsequent operation, the operator puts the yarn between the draw-off rollers responsible for the draw-off speed during the spinning.

The manual spinning-in can be successfully applied in rotor spinning machines operating at small draw-off speed of the yarn in process of formation which is adverse to the interest of both the producers and the users of the rotor spinning machines in raising the productiveness of such machines. After the bobbin has come into contact with its drive roller, a time interval is required to speed it up to the circumferential velocity corresponding to the draw-off speed of the yarn. This time interval increases with the draw-off speed and with the increasing mass of the bobbin. Due to the bobbin start process, the instantaneous yarn speed of the yarn at the moment when the yarn end has reached the collecting groove of the spinning rotor is inferior to the operating draw-off speed of the yarn in process of production so that at the piecer (junction spot of the yarn end with the fibre band) a certain number of fibres with a twist number different from that of the neighbouring yarn section is being deposited. The piecer then forms a thickened yarn section detectable by sight during the turtner processing and representing a serious aesthetic defect not only of the yarn but also of the products made of it.

In view of its drawbacks, the manual spinning-in has been step by step replaced by the automatic one developed substantially in two directions, viz., either by means of mechanisms of the operating unit or by means of an attending device adapted to move along the machine and to stop at any chosen operating unit.

The spinning-in automation by means of mechanisms of the operating unit, for instance as disclosed in the CZ 200 910, has proved to be too complicated and expensive because it requires that the yarn delivery after its rupture is stopped with the yarn end remaining inside the delivery tube which is impossible to obtain at high yarn draw-off speeds.

The automated spinning-in by means of an attending device is at present the most widely used method of automatic yarn spinning-in on rotor spinning machines. As an example, in the CZ patent application 2694-95, after the yarn rupture on a rotor spinning machine, as a first step the yarn end on the lifted bobbin is first detected by means of underpressure and sucked into a detecting nozzle. In the next step the required yarn spinning-in length is unwound from the bobbin, the yarn is moved to the spinning unit and acted upon by the means of the attending device so as to assume its travel path passing via all means of the operating unit being attended except the yarn distribution mechanism. At the end of the metered-out yarn length there is formed the yarn spinning-in end which is in a first step by means of underpressure partly introduced into the spinning rotor. The yarn is then acted upon by deflecting means of the attending device between the spinning unit and the draw-off mechanism of the attended operating unit of the machine and then, upon the suspension of this action the spinning-in yarn end comes onto the collecting groove of the spinning rotor and is there continuously joined by the fibres of the fibre band generated in said collecting groove. The yarn is then exposed to the action of due means of the operating unit intended to draw-off, monitor, and wind the yarn that is then handed over from the attending device to the distribution device of the attended operating unit of the machine. This permits repeatedly to obtain the same quality and size of the piecer.

High quality and small size of the piecer will be obtained even at high draw-off speeds of rotor spinning machines.

The drawback of this spinning-in method consists in increased requirements imposed upon the technical qualification of the operator for correctly adjusting the attending device so that in spite of the due quality of the produced yarn and high productiveness the rotor spinning machines with this spinning-in system have found but a difficult access in particular in areas with comparatively low technical level of the workforce.

Principle of the Invention The drawbacks of the state of art have been reduced or totally removed by the method according to the invention whose principle consists in that prior to being spun- in the yarn is led into its travel path at the operating unit of a rotor spinning machine and passes through a draw-off mechanism, i.e., between a draw-off roller and a pressure roller tilted away from the draw-off roller, is deflected from its travel path by at least one deflecting means of the operating unit of the spinning machine while passing outside the distribution mechanism whereupon the deflecting member is released and due to this the spinning-in yarn end comes onto the collecting groove of the spinning rotor on which prior to this was formed a fibre band beginning then to join it whereupon, at a predetermined time interval after the yarn spinning-in end has come onto the collecting groove of the spinning rotor, the draw-off mechanism of the operating unit of the spinning machine begins to draw off the yarn, and the winding mechanism of the operating unit of the spinning machine begins to wind it.

This method permits to increase the quality of the piecers and by means of this the quality of the resulting yarn which is substantially influenced by the quality of the piecers. It also increases the efficiency and reliability of the spinning-in operation while at the same time reducing the requirements imposed upon both the qualification level and the time of the operator.

Preferably, prior to its spinning-in, the yarn is deflected from its travel path in front of the distribution mechanism and over the outlet aperture of the delivery tube, over the outlet aperture of the delivery tube being deflected by a distance equal to the distance between the spinning-in yarn end and the collecting groove of the spinning rotor, and the deflection over the outlet aperture of the delivery tube is cancelled after the spinning-in process has been completed.

in this manner the spinning-in reliability is still more increased since the yarn suction into the rotor is obstructed by no other means, and the distance between the deflection spot and the outlet aperture of the delivery tube is reduced to a minimum.

A further improvement of the preceding method is achieved by cancelling the yarn deflection in front of the distribution mechanism only after the start of both the yarn draw-off by means of the draw-off mechanism and of the yarn winding by means of the winding mechanism thus handing the yarn over to the distribution mechanism and preventing it from the risk of being broken by the distribution mechanism during the spinning-in process.

In an economical variant of the method according to the invention, the yarn is deflected only from the distribution device, and the deflection cancelling process is carried out in two steps the first of which, carried out before the spinning-in, returns the spinning-in yarn end onto the collecting groove of the spinning rotor, and the second one, carried out after the draw-off and winding have been started, sets the yarn free for the distribution mechanism.

It is advantageous to monitor the presence, and evaluate the quality, of the yarn between its outlet out of the delivery tube and to stop the operating unit if yarn absence or bad quality has been detected.

The principle of the device for carrying out the above method on an open-end spinning machine consists in that the arms of the winding device and the pressure lever of the draw-off mechanism are coupled with a control electromagnet interconnected with a control unit, the control unit being connected also with a yarn deflecting member intended to deflect the yarn from its travel path, the yarn lying before and during the spinning-in process in its travel path between the draw-off roller and the pressure roller tilted away from the draw-off roller, of the draw-off mechanism.

It is advantageous if the deflecting member is made as a deflecting member situated over the outlet aperture of the delivery tube.

In another embodiment, the deflecting member is made as a deflecting member of the distribution.

From the point of view of the reliability of the spinning-in process, it is advantageous if the deflecting member is adapted to take up two defined positions while in contact with the yarn, and more exactly, a position deflected to the maximum before the spinning-in, and a less deflected position during the spinning in.

To improve the yarn quality, a sensor of yarn presence and quality, adapted to measure the quality and size of the piecer and coupled with the control unit so as to be able to stop the operating unit in case of bad quality of the yarn or of the piecer is situated between the outlet aperture of the delivery tube and the winding mechanism.

The top quality of the yarn in process of formation can be monitored by situating said sensor in said position.

It is advantageous to fit the control unit with a switch situated within the reach of the operator on the operating unit of the spinning machine.

Description of the Drawinas Examples of embodiment of a device for carrying out the method according to the invention are schematically shown in the accompanying drawings showing in Fig. 1 an operating unit of an open-end spinning machine with its mechanisms in their operating positions taken up during the spinning, in Fig. 2 the operating unit of the open-end spinning machine after the yarn rupture with a device for individual spinning- in, and in Fig. 3 another variant of a device for individual spinning-in on the operating unit of the machine.

Examples of embodiment of the invention The rotor spinning machine comprises a plurality of operating units arranged side by side, each operating unit adapted independently to produce yarn from a textile fibre sliver and to wind the produced yarn on a bobbin.

Each operating unit comprises a spinning unit 1 situated over a sliver can 2 from which a textile fibre sliver 3 is led into a sliver feed device 11 of a spinning unit 1. A sliver feed device 11 is followed by a singling-out device 12 used to separate the sliver 3 into individual fibres. Related to the singling-out device 12 is a transport channel 13 for the singled-qutfibres leading into the inner space of a spinning rotor 14 in whose widest section there is formed a collecting groove 141 for collecting the fibres into a fibre band 31 under the action of the centrifugal force generated by the rotating spinning rotor 14.

The spinning rotor 14 is made in one of the well-known variants, i.e., it consists either of an open rotation body fitted with not shown air vents used to generate underpressure in the inner space of the spinning rotor in response to its rotation, or it consists of a full-wall open rotation body with out air vents seated in an underpressure chamber whose underpressure at the same time generates the underpressure in the inner space of the spinning rotor 14.

In a well-known manner, the fibre band 31 is transformed into yarn 32 delivered from the spinning rotor 14 by a delivery tube 15 from which it is led into a draw-off mechanism 4 consisting in the shown embodiment in a draw-off roller 41 mounted on a through draw-off shaft 42 common to all operating stations on one machine side and arranged through along the machine length.

The draw-off mechanism 4 also comprises a pressure roller 43 seated on a pressure lever 44 bearing in its operating position onto the circumference of its related draw-off roller 41 and used to press on the yarn 32 whose travel path passes between the draw-off roller 41 and the pressure roller 43. In the second position of the pressure roller 43, its circumference is out of contact with the circumference of the draw-off roller 41. The pressure lever 44 is coupled with a control electromagnet 5 in the shown example of embodiment by means of a first control tie rod 51, and the control electromagnet 5 is coupled with a control unit A.

Situated between the outlet aperture of the delivery tube 15 of the spinning unit 1 and the draw-off mechanism is a sensor 6 monitoring the presence and quality of yarn 32 which is led through it, and coupled in the shown embodiment with the control unit A.

Yarn 32 is led from the draw-off mechanism via a sensor 7 of the yarn presence and a well-known yarn distribution mechanism 8 into a winding mechanism 9 comprising a through drive cylinder 91 onto which there is in a well-known manner pressed a winding bobbin 92 whose tube 93 is fastened in arms 94 of a bobbin holder, the arms being in a well-known manner adapted to tilt away from the drive cylinder 91 of the winding device 9 for stopping the yarn winding, i.e., the bobbin rotation, upon the interruption of the spinning process. At the same time, said arms 94 of the bobbin holder are arranged so as to open from each other and thus to permit a fully wound bobbin 92 to be taken out and an empty tube 93 to be inserted between said arms 94 of the bobbin holder. The sensor 7 monitoring the presence of the yarn 32 is coupled with the control unit A.

The arms 94 of the bobbin holder are coupled with the control electromagnet 5, in the shown example of embodiment by means of a second control tie rod 52.

A deflecting yarn distribution member 10, coupled with a deflecting yarn distribution electromagnet 101 and reaching into the travel path of the yarn 32 between the sensor 7 of the yarn presence and the winding mechanism 9 is used to deflect the yarn 32 out of its travel path so as to produce a reserve length of the yarn 32 required for the spinning-in process.

The control electromagnet 5 and the deflecting yarn distribution electromagnet 101 are equipped with supply circuits interconnected with the control unit A of the operating station that is interconnected also with the control device of the sliver feed device 11 made in the shown example of embodiment as an eiectromagnetic clutch 111 of the feed device 11. The control unit A is fitted with a switch S situated accessibly to the operator on the operating station of the machine.

Provided on the body of the spinning unit 1 at a point within and at the boundary of the reach of the end of yarn 32 from the bobbin 92 at the length of the yarn 32 required for the spinning-in is a well-known not shown yarn severing means or a measuring device M intended to inform the operator about where the yarn 32 is to be severed.

To increase the spinning-in quality, the device can be complemented by a spinning-in yarn deflecting member 20 coupled with a spinning-in yarn deflecting electromagnet 201 fitted with a control circuit interconnected with the control unit A. as shown in Fig. 3. The spinning-in yarn deflecting member 20 is seated between the outlet aperture of the delivery tube 15 and the draw-off mechanism 4 or the sensor of the quality and presence of the yarn 32 and is used to produce the spinning-in yarn reserve by deflecting the yarn 32. In this embodiment, the deflecting yarn distribution member 10 just defines the path of the yarn outside the yarn distribution mechanism at the lifted position of the bobbin 92. The deflecting yarn distribution member 10 need not be used in such machine embodiment which ensures that at the lifted position of the bobbin 92 the path of the yarn 32 cannot interfere with the path of the yarn distribution mechanism 8.

When a yarn rupture occurs or when the bobbin 92 has received a predetermined length of the yarn 32 wound onto it, the feed device 11 of the sliver 3 is stopped in a well-known manner, and the wound bobbin 92 fastened between the arms 94 moves away from the drive cylinder 91 and stops as well.

The tilting-away motion of the arms 94 of the winding mechanism 9 results in a change of the position of the second control tie rod 52 of the control electromagnet 5, and jointly with it, of the first control tie rod 51 which will turn the pressure lever 44 of the draw-off mechanism so as to move the pressure roller 43 away from the draw-off roller 41.

The deflecting yarn distribution electromagnet 101 moves the deflecting distribution member 10 of the yarn 32 to its deflected position.

In case of a yarn rupture on an operating unit, the operator cleans the spinning rotor 14, detects the yarn end on the bobbin 92 and starts unwinding the yarn 32.

During the unwinding, the operator leads the yarn 32 from the lifted bobbin 92 via the deflecting yarn distribution member 10. into the sensor 7 of the yarn presence 32 inserts it into the draw-off mechanism, i.e., between the pressure roller 43 and the draw-off roller 41 tilted away from the pressure roller 43. leads it into the sensor 6 monitoring the presence and quality of the yarn 32. puts it to the measuring device M or to the severing means, shortens it to the length required for the spinning-in, thus creating on the yarn 32 wound off from the bobbin 92 a spinning-in end to be inserted then by the operator into the outlet aperture of the yarn delivery tube 15 into which it will be sucked due to the underpressure existing in the spinning rotor 14.

At this stage, the yarn 32 led from the bobbin 92 via the deflecting yarn distribution member passes through the sensor 7 monitoring the presence of the yarn 32 through the draw-off mechanism 4 i.e., between the rotating draw-off roller 41 and the pressure roller 43 tilted away from it, through the sensor 6 monitoring the quality and presence of the yarn 32 and enters the delivery tube 15 towards the spinning rotor 14 however, without reaching as far as the collecting groove 141 of the spinning rotor 14. The feed device 11 of the sliver 3 is stopped, the spinning rotor 14 rotates, and the attended operating unit is ready to carry out the spinning-in operation. At this, the yarn 32 lies in a path differing from its regular spinning path only in that it is held outside the yarn distribution mechanism 8 by means of the deflecting yarn distribution member 10.

The spinning-in process proper is initiated by the operator by switching in the switch S of the control unit A which engages the clutch 111, sets into rotary motion the feed rollers of the feed device 11 and thus starts the feed of the sliver 3 to the singling- out device 12 from which the fibres are led through the transport channel 13 into the spinning rotor 14 where they are transformed into the fibre band 31 on the collecting groove 141 of the spinning rotor 14. Before the creation of said fibre band 31, the control unit A activates the deflecting yarn distribution electromagnet 101 which sets free the deflecting yarn distribution member 10 of the yarn 32 which is released from the deflecting distribution member 10 and whose spinning-in end is sucked into the spinning rotor 14 where it reaches as far as the collecting groove 141 on which it is in a well-known manner joined by the fibre band 31 to form the yarn 32. After the fibre band 31 has been connected to the yarn 32 the control unit activates the control electromagnet 5 which actuates the first control tie rod 51 so as to turn the pressure lever 44 back to a position in which the pressure roller comes into contact with the rotating draw-off roller 41, grips the yarn 32, and begins to draw it off from the spinning rotor 14. By means of the second control tie rod 52, the control electromagnet 5 at the same time begins to tilt the arms 94 of the winding mechanism 9 to a position in which the bobbin 92 comes to sit on the drive cylinder 91 and the yarn 32 begins to be wound on the bobbin 92. Simultaneously with the start of the activity of the draw-off mechanism 4 the control unit A activates the sensor 6 of the quality and presence of the yarn 32 and the sensor 7 of the presence of the yarn 32, or begins to process the signals emitted by said sensors 6 7 Thus is measured also the quality of the junction spot of the spinning-in end of the yarn 32 with the fibre band 31, called "piecer", and following that, the quality of the yarn in process of formation. Each of the two sensors 6,Z monitors the presence of the yarn 32.

The fact that the spinning-in is carried out manually by the operator has no influence on the quality of the piecer because the spinning-in operations proper are performed by the means of the operating unit of the spinning machine. Thus, the machine may be attended by a not trained operator with only a minimal skill.

If the yarn 32 has been completely released from the deflecting yarn distribution member 10 before the spinning-in, there is a risk for the yarn 32 of getting caught by the yarn distribution mechanism 8 prior to the spinning-in completion. To eliminate the risk, the deflecting yarn distribution member 10 has in a further embodiment a defined spinning-in position ZP chosen so as to ensure that the difference in the length of the yarn 32 passing via the deflecting yarn distribution member 10 in its deflected position VP and its spinning-in position ZP is equal to the distance between the spinning-in end of the yarn 32 in the delivery tube 15 and the collecting groove 141 of the spinning rotor 14 as shown in Fig. 2. Consequently, before the spinning-in, the deflecting yarn distribution member 10 moves from the deflected position VP to the spinning-in position ZP, and in response to this the spinning-in end of the yarn 32 moves onto the collecting groove 141 of the spinning rotor 14 where it begins to be joined by the fibre band 31.

Only after the control unit A has given instructions for resuming the draw-off, winding, and monitoring of the yarn 32, the control unit A activates the deflecting yarn distribution electromagnet 101 so as to move the deflecting yarn distribution member 10 to its released position lying outside the travel path of the yarn 32. When set free of the deflecting yarn distribution member 10, the yarn 32 is gripped by the yarn distribution mechanism 8 to be croswound on the bobbin 92.

In the embodiment shown in Fig. 3, the spinning-in process is analogical except that the reserve of the yarn 32 for the spinning-in proper is actuated by means of a deflecting yarn distribution member 20 actuated in turn by a deflecting yarn distribution electromagnet 201 in response to the instructions of the control unit A.

The deflecting yarn distribution electromagnet 201 and the deflecting yarn distribution electromagnet 101 can be replaced by another suitable well-know device such as a pneumatic cylinder, a step motor, etc.