Background art For resuming the spinning after a yarn rupture, known attending devices of open-end spinning machines are fitted on the operating unit with a detecting device of yarn end on the bobbin lifted out of contact with its driving roller. The detecting device comprises a detecting nozzle adapted to be connected to an underpressure source and to be placed near the bobbin circumference. With the detecting device there are connected a yarn transfer device intended to bring the yarn to the spinning unit and means for unwinding a yarn length required for the spinning-in. The attending device also comprises means for severing the yarn at a predetermined place and creating a yarn end suitable for spinning-in. The attending device is also required to contain means for introducing yarn into the spinning rotor and for letting said yarn end drop on the collecting groove of the spinning rotor of the spinning rotor as well as means for consuming the yarn loop produced after the spinning-in at the beginning of the yarn winding due to the fact that the yarn delivery speed is superior to the yarn winding speed.

In CS 212263, after the yarn spinning-in has been completed, there is reversed the run of auxiliary draw-off rollers that begin to draw off yarn from the spinning device. At the same time, an auxiliary driving roller of the attending device begins to turn the bobbin in reverse direction. When the speeds of all components of the operating unit have been equaled to their operation speed, the mechanisms of the attending device pass the yarn to the mechanisms of the attended operation unit of the machine.

The drawback of this solution consists in the complicated way of passing the yarn to create the yarn length required for spinning-in resulting in lack of precision in the operation of the attending device whose mechanism fails reliably to grip the yarn and reliably to transfer it to a next operation. By this, the reliability of spinning-in by the attending device is impaired. Another drawback consists in the necessity of sucking into the detecting nozzle a considerably long yarn section already in the first stage of operation in order to permit its drawing out of the detecting nozzle in the next stage of operation which in particular increases the time required for attending the operating unit. Still another drawback consists in the large distance between the auxiliary draw-off rollers of the attending device and the mouth of the delivery tube involving the risk that during the last reverse unwinding motion of the auxiliary draw- off rollers the unwound yarn length for various reasons and low tension of the yarn on this free path of its fails to be sucked into the delivery tube and to be spun in.

Very complicated are also the operation of passing the thread after the spinning-in from the means of the attending device to the due means of the attended operating unit of the machine and the operation of passing the winding bobbin set in rotary motion by a driving roller of the attending device to the driving roller of the winding device of the attended operating unit of the machine.

The yarn end is detected on the bobbin, its required length is metered, the spinning-in end of the yarn is inserted into the spinning rotor, and its end brought to the collecting groove of the spinning rotor and there connected with the fibre band.

The means of the attending device set then the lifted bobbin in rotary motion in the winding sense so that the yarn is drawn off from the spinning device by the winding bobbin and only at the stabilization of the winding and spinning parameters is handed over to the draw-off mechanism of the attended operation unit and the winding bobbin is tilted to the driving roller of the operating unit thus completing the spinning-in process.

The means of the attending device fail to impart to the bobbin, especially if it is already wound to a considerable extent, its full operation speed from the very beginning. For this reason, this solution and also the similar ones carry out the spinning-in at reduced speed of the spinning rotor so that the winding speed, as well, is reduced at the beginning. The speed of the spinning rotor gradually increases after the spinning-in up to its operation speed, and the rotation speed of the bobbin drawing the yarn from the rotor is required to increase at the same degree which places heavy demands on the complicatedness of the attending device and increases the total time required for spinning in the operating unit after the yarn rupture. If the increase in speed is not accompanied by the modification of the speed with which the sliver is fed to the spinning unit the yarn spun is thicker than that spun at full speed. The realization of such speed modification substantially increases the complicatedness both of the attending device and of the attended operating unit.

Principe of the invention The drawbacks of the background art have been eliminated by the method of yarn loop consumption according to the invention whose principle consists in that the bobbin, after being spun-in, is set in contact with the driving roller and thus set in rotary motion in the winding sense, then set out of contact with the driving roller and accelerated to a circumferential velocity superior to the operation winding velocity, then the acceleration to said superior circumferential velocity is stopped, the bobbin reset in contact with the driving roller, the bobbin circumferential velocity thus reduced to said operation winding velocity, and the size of the yarn loop due to the overproduction of yarn at the start of the bobbin rotary motion is thus reduced.

Preferably, the bobbin is set out of contact with the driving roller after having reached its operation winding velocity.

Preferably, the bobbin acceleration is stopped before the yarn loop consumption.

Preferably, the bobbin acceleration is stopped at the yarn loop consumption.

Preferably, the bobbin acceleration is stopped by resetting the bobbing in contact with the driving roller.

Preferably, not later than after the first setting of the bobbin in contact with the driving roller, the rotation speed of the bobbin is monitored and compared with the operation winding velocity of the bobbin corresponding to the bobbin diameter at the given moment.

Preferably, the time course from the spinning-in moment through the first setting of the bobbin in contact with the driving roller, the moment of the bobbin setting out of the contact with the driving roller, and the moment of its resetting in contact with the driving roller are governed in accordance with a time schedule determined on the basis of the yarn thickness, the draw-off speed, and the diameter of the bobbin at the given moment.

Description of the drawings An example of embodiment of a device for spinning-in yarn on a rotor spinning machine according to the invention is schematically shown in the accompanying drawings 1 to 3 in which only mechanisms having reference to the yarn spinning-in are illustrated.

Examples of embodiment of the invention An open-end spinning machine consists of a plurality of operating units situated next to each other. Each operating unit independently produces yarn from a sliver of textile fibers and winds it on a bobbin, which can be a cone or a cylindrical bobbin, as needed in a given case.

Each operating unit comprises a spinning unit 1 into which a sliver 2 is supplie from a not represented sliver can by a feeding device 3 from which the sliver 2 is taken by a singling-out device 4 by which the sliver 2 is separated into single fibres which are in a well-known way by underpressure fed into the spinning rotor 5. The underpressure is produced in the spinning rotor 5 either by the rotation of the spinning rotor 5 fitted on its periphery with air vents or by placing the spinning rotor 5 made of full material in an underpressure chamber. Both of these methods of producing the underpressure in the spinning rotor 5 are well-known, and the method of yarn spinning-in according to the present invention can be applied to both of them. Singled-out fibres, brought by underpressure into the spinning rotor 5, are in a well-known way exposed to a centrifugal force generated by the rotation of the spinning rotor 5 and by this placed on a collecting groove 51 where they produce a fibre band 6 which is then in a well-known way transformed into yarn 7.

The spun yarn 7 is led from the spinning rotor 5 by a yarn delivery tube 8 to a draw-off mechanism 9 consisting in the shown embodiment of a draw-off roller 91 extending along one machine side and common for all the operating units of said machine side and of a pressure roller 92 which is a component of each operating unit and serves to press the yarn 7 to the draw-off roller 91. Behind the draw-off mechanism 9, the yarn 7 passes across a well-known not illustrated yarn rupture sensor monitoring the yarn presence. From the draw-off mechanism 9, the yarn 7 is led across said not illustrated yarn rupture sensor and a distributing device 10 made in one of well-known ways into a winding device 11. The winding device 11 comprises a driving roller 111 extending along the machine length onto which there is in a well-known way pressed a bobbin 112 whose tube 113 is fixed in the arms of a bobbin holder 114 which arms are in a well-known way adapted to be tilted away from the driving roller 111 of the winding device 11 so as to interrupt the winding upon interruption of the spinning process, and also adapted to be spaced apart in order to permit the wound bobbin 112 to be taken out and an empty tube 113 to be put in.

To resume the spinning after a yarn rupture or after the empty tube 113 has been substituted for the full bobbin 112, the end of the yarn 7 must be inserted into the spinning rotor 5 and made to be connected with the fibre band 6 produced in a well-known way in the spinning rotor 5 from singled-out fibres. After the end of the yarn 7 has been connected to the fibre band 6, i. e., after the spinning-in has been carried out, the spun yarn 7 begins to be drawn-off from the spinning rotor 5, and the yarn winding on the bobbin 112 or on the tube 113 is resumed. Although the spinning-in can be carried out manually, the requirements of the spinning machine users on the quality of the connection of the yarn 7 with the fibre band 6, known as piecer, prefer the spinning-in to be carried out by an attending device 12 which thus takes up the function of the machine operator.

The attending device 12 is in a well-known way, for instance by being mounted on a rail, adapted to move along the operating units of an open-end spinning machine and it contains means for controlling functions and function components of the operating units. In its turn, the attending device 12 itself is in the examples of embodiment controlled by a not illustrated control unit which can be made as a part of the attending device 12. The description of the examples of embodiment of this invention will refer only to the parts of the attending device 12 that are active in the yarn spinning-in process. For simplification, the other parts of the attending device 12 will be omitted in the description as irrelevant to the object of this invention.

In case of an interruption of the spinning process on an operating unit, due whether to a yarn rupture or to the completion of yarn winding on the bobbin 112 achieved when either a predetermined yarn length has been wound or a predetermined diameter of the bobbin 112 has been reached and the wound bobbin 112 is to be replaced by the empty tube 113, the operating unit is in waiting for the attending device 12 in order to resume the spinning. In this stage, the bobbin 112 or the tube 113 is in its lifted position out of contact with the driving roller 111 of the winding device 11.

The attending device 12 comprises a frame 13 on which there is seated a transport mechanism 14 fitted with transport wheels 141 resting on a transport rail 15 extending at least along the operating units of one machine side. The transport mechanism 14 serves to move the attending device 12 to required positions.

Situated on the frame 13 of the attending device 12 is a bobbin motion starting device 16 containing a rotatably mounted arm 161 having rotatably mounted thereon a drive pulley 162 coupled with a well-known not shown bidirectional drive coupled with an also not illustrated control unit. The arm 161 of the bobbin motion starting device 16 is adapted to tilt between its rest position in which it lies inside the frame 13 of the attending device 12, and its operative position in which the drive pulley 162 is in contact with the periphery of the bobbin 112 or of the tube 113 in the lifted position of the latter.

Situated on the frame 13 of the attending device 12 in the area between the draw-off mechanism 9 and an auxiliary yarn guide 19 of the operating unit is a compensator 20 of a yarn loop 71 due to the overproduction of yarn 7 at the start of the bobbin 112 after the spinning-in when the draw-off speed of the yarn 7 is superior to its winding speed. In the shown embodiment, the compensator 20 is a mechanical one and comprises a revolving arm 201 coupled with a compensation motor 202. The extremity of the revolving arm 201 carries a catching eye 203. A position sensor 21 is related to the terminal releasing position of the revolving arm 201 of the compensator 20.

In another, not shown example of embodiment, the auxiliary yarn guide of the operating unit can be replaced by an auxiliary yarn guide adjustably situated on the attending device. Also the compensator 20 can be a mechanical one or one of the shown pneumatic compensators.

All the above drives, whether consisting of electromotors, pneumatic cylinders or other well-known means, are coupled with the control unit of the attending device 12 which serves in particular to control and coordinate their functions.

In case of a yarn rupture or when a required yarn length has been wound on the bobbin 112, the feeding device 3 of the sliver 2 stops in a well-known way, the bobbin 112 wound or in process of winding moves out of contact with the driving roller 111 and stops as well. When the attending device 12 arrives at the operating unit it first must be ascertained which operation cycle of the attending device 12 is to be chosen, i. e, either the replacement of the full bobbin 112 by the empty tube 113 with subsequent resumption of the spinning process on the empty tube 113, or the resumption of the spinning process on the operating unit in question after a yarn rupture, i. e., winding on the existing bobbin 112. This can be determined for instance by means of the arm 161 of the bobbin motion starting device 16. If the arm 161 of the bobbin motion starting device 16, while moving to the bobbin 112, finds neither the bobbin 112 nor the empty tube 113, the operation of the attending device 12 switches to the spinning-in after the doffing of the bobbin 112 which lies outside the scope of this patent. On the contrary, if said arm 161, while moving to the bobbin 112, comes to lie on the bobbin 112 or tube 113, it starts the cycle of spinning-in after yarn rupture. At least some items of the above information on the condition of the operating unit of the machine can be handed over to the attending device from the operating unit of the machine by one of well-known methods.

To resume the spinning process on the operating unit in question after the rupture of the yarn 7, first is set in action the bobbin motion starting device 16 of the bobbin 112 whose arm 161 tilts towards the machine until the drive pulley 162 of the arm 161 of the bobbin motion starting device 16 comes to lie on the periphery of the bobbin 112. After said spinning-in of yarn 7, carried out at full machine speed, the draw-off mechanism 9 is set in motion and begins to draw off the yarn 7 from the spinning unit 1. Due to the low mass of the pressure roller 92 of the draw-off device 9, almost no slippage takes place, and it can be stated that the draw-off of the yarn 7 begins immediately after the pressure roller 92 has come into contact with the driving roller 91 of the draw-off mechanism 9 and the yarn 7 has got gripped between them.

Even if the bobbin 112 comes to lie on the driving roller 111 of the winding device 11 at the same time as the pressure roller 92 comes to lie on the driving roller 91 of the draw-off mechanism 9, its start is slower and, in the interval before the bobbin 112 reaches its full operation speed, an increased amount of yarn 7 is created between the draw-off mechanism 9 and the winding device 11 due to the yarn overproduction by the draw-off mechanism 9. For this reason, the compensator 20 of the attending device 12 is set in action immediately after the spinning-in and after the start of the winding, and the eye 203 of its revolving arm 201 catches the yarn 7 in the area over the draw-off mechanism 9, i. e., between the draw-off mechanism 9 and the auxiliary yarn guide 19 of the operating unit of the machine. The action of the force of the compensator 20 holds a constant tension in the yarn 7 and prevents the loops of the yarn 7 from being transferred into the winding in formation on the bobbin 112.

At the latest at the moment when the bobbin 112 in contact with the driving roller 111 of the winding device 11 reaches its full operation speed, a lifting device 121 of the attending device 12 is set in action and moves the bobbin 112 to a position out of contact with the driving roller 111 of the winding device 11. After loosing said contact with the driving roller 111, the bobbin 112 begins to accelerate under the action of the drive pulley 162 of the bobbin motion starting device 16 from which it receives acceleration to a speed superior to the operation winding velocity of the bobbin 112. At this stage, the yarn winding speed is superior to the speed of the draw-off mechanism 9 so that the yarn loop previously formed gets consumed and the revolving arm 201 of the compensator 20 gets back to its basic position in which the yarn 7 is free to fall out of the eye 203 of the compensator 20.

As soon as the revolving arm 201 of the compensator 20 reaches its basic position, the position sensor 21 sends out a signal reporting the consumption of the loop 71 of the yarn 7, and the lifting device 121 moves the bobbin 112 back on the driving roller 111 of the winding device 11 thus decelerating the bobbin to its operation winding velocity. While being set in contact with the driving roller 111, the bobbin 112 looses contact with the drive pulley 162 of the bobbin motion starting device 16, and the bobbin motion starting device 16 takes up its rest position in the attending device 12. Throughout the period of the motion start of the bobbin 112 and of the yarn loop 71 consumption, the yarn 7 is led via a gripping hook 181 of yarn length metering mechanism 18 so that it passes beyond a yarn distributing device 115. The yarn 7 is set free from the gripping hook 181 after the loop 71 of the yarn 7 has been consumed.

The drive pulley 162 of the bobbin motion starting device 16 can contact the periphery of the bobbin 112 either during the whole above described process of the consumption of the loop 71 of the yarn 7, as is the case in the illustrated embodiment, or only in its lifted position in the stage of imparting to the bobbin 112 speed superior to its operation winding velocity, when the bobbin has already received from the driving roller 111 speed equal or inferior, to its operation winding velocity.

Analogically, the lifting device 121 need not be in contact with the arms of the bobbin holder at all times but only at the stage of moving the bobbin 112 out of contact with the driving roller 111 and holding it in this out-of-contact position.

Since the drive pulley serves to accelerate a bobbin being already in rotary motion, there is no need to increase the pulley dimensions or the input power of its drive as compared with the drive pulley 162 serving for unwinding the yarn 7 for spinning-in. Besides, in the first stage of the acceleration of the bobbin 112 when it is set in motion from its rest position to its predetermined speed it is driven by the driving roller 111 that contacts it throughout its length thus reducing the danger of damaging the yarn in process of winding.

In the method according to the invention in the shown example of embodiment, the bobbin 112, after being spun-in, is set in contact with the driving roller 111 and thus set in rotary motion in the winding direction, then is set out of contact with the driving roller 111 and accelerated to a circumferential velocity superior to its operation winding velocity, then said acceleration to said circumferential velocity superior to its operation winding velocity is stopped, the bobbin 112 resumes its position in contact with the driving roller 111 and thus decelerated to its operation winding velocity. In this way, the size of the loop 71 of the yarn 7 due to the overproduction of the yarn 7 at the start of the bobbin motion is reduced. After reaching its operation winding velocity, the bobbin 112 gets out of contact with the driving roller 111, and the acceleration of the bobbin is finished before the consumption of the loop 71 of the yarn 7. In another embodiment, the acceleration of the bobbin 112 can be terminated only at the stage of the completed consumption of the loop 71 of the yarn 7.

In the practice, the acceleration of the bobbin is terminated by its setting in contact with the driving roller 111.

In another embodiment, the rotation speed of the bobbin 112 is monitored at the latest after its first setting in contact with the driving roller 111 and is compared with the operative rotation speed of the bobbin 112 corresponding to the diameter of the bobbin 112 existing at the given moment.

The time course from the spinning-in moment through the first setting of the bobbin 112 in contact with the driving roller 111, the moment of the bobbin 112 setting out of contact with the driving roller 111, and the moment of its resetting in contact with the driving roller 111 are governed in accordance with a time schedule determined on the basis of the yarn thickness, the draw-off speed, and the diameter of the bobbin at the given moment.