METHOD FOR AUTOMATICALLY PIECING A THREAD AT A WORKSTATION OF A TEXTILE MACHINE, AND TEXTILE MACHINE

Abstract

A method for automatically piecing a thread at a workstation of a textile machine, includes seeking an end of the thread on a surface of a bobbin with a suction nozzle and unwinding the thread from the bobbin counter to a regular draw-off direction of the thread and sucking the thread into the suction nozzle. The bobbin is driven in a direction of reverse rotation with a drive. A thread loop is draw-opened in the thread and moved towards a piecing unit via movement of a feeder unit. The bobbin is driven in the direction of reverse rotation during the drawing-open of the thread loop such that the thread is unwound from the bobbin. A speed of reverse rotation of the bobbin is coordinated with movement of the feeder unit.

Claims

1-10. (canceled)

11. A method for automatically piecing a thread at a workstation of a textile machine, comprising: seeking an end of the thread on a surface of a bobbin with a suction nozzle; unwinding the thread from the bobbin counter to a regular draw-off direction of the thread and sucking the thread into the suction nozzle; driving the bobbin in a direction of reverse rotation with a drive for the unwinding of the thread; draw-opening a thread loop in the thread and moving the thread loop towards a piecing unit via movement of a feeder unit; driving the bobbin in the direction of reverse rotation during the drawing-open of the thread loop such that the thread is unwound from the bobbin; and coordinating the a speed of the reverse rotation of the bobbin with movement of the feeder unit.

12. The method as in claim 11, wherein the reverse rotation speed of the bobbin is coordinated such that a thread length withdrawn from the bobbin is made available synchronously to a thread length required for forming the thread loop.

13. The method as in claim 11, wherein the reverse rotation speed of the bobbin is coordinated such that at all time during the reverse rotation of the bobbin, a thread length withdrawn from the bobbin is less than a thread length required for forming the thread loop.

14. The method as in claim 11, wherein the reverse rotation speed of the bobbin is coordinated such that at all time during the reverse rotation of the bobbin, a thread length withdrawn from the bobbin is greater than a thread length required for forming the thread loop.

15. The method as in claim 11, wherein the drive is driven according to a speed profile during movement of the feeder unit.

16. The method as in claim 11, further comprising measuring a tensile force of the thread during movement of the feeder unit and controlling the drive according to the measured tensile force.

17. A textile machine comprising a workstation, the workstation further comprising: a suction nozzle for seeking an end of a thread on a surface of a bobbin and sucking in the thread; a drive configured to drive the bobbin such that the thread is withdrawn from the bobbin counter to a regular draw-off direction of the thread; a piecing unit; a feeder unit configured to drawn-open a thread loop in the thread withdrawn from the bobbin and move the thread loop towards the piecing unit; and a controller configured for operating the drive in a direction of reverse rotation during the draw-opening of the thread loop such that the thread is unwound from the bobbin and a speed of the reverse rotation of the bobbin is coordinated with movement of the feeder unit.

18. The textile machine as in claim 17, wherein the drive and the feeder unit are situated at the workstation.

19. The textile machine as in claim 17, wherein the feeder unit moves in a pivoting motion.

20. The textile machine as in claim 17, further comprising a measuring unit disposed to measure a tensile force of the thread sucked into the nozzle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Further advantages of the invention are described with reference to the exemplary embodiments represented in the following. Wherein:

[0021] FIG. 1 shows a schematic sectional representation of a workstation of a textile machine during the regular operation;

[0022] FIG. 2 shows the workstation after an interruption of the regular operation, wherein a thread has been sucked into a suction nozzle;

[0023] FIG. 3 shows the workstation of the textile machine in a further situation, in which a thread loop is being formed; and

[0024] FIG. 4 shows the workstation of the textile machine in a situation, in which the formation of the thread loop has just been ended and the thread is being moved toward a piecing operation.

DETAILED DESCRIPTION

[0025] Reference will now be made to embodiments of the invention, one or more examples of which are shown in the drawings. Each embodiment is provided by way of explanation of the invention, and not as a limitation of the invention. For example features illustrated or described as part of one embodiment can be combined with another embodiment to yield still another embodiment. It is intended that the present invention include these and other modifications and variations to the embodiments described herein.

[0026] FIG. 1 shows a schematic sectional representation of a workstation 2 of a textile machine 1. The workstation 2 includes a spinning device 3 in the usual way, with the aid of which a thread 4 is produced. The thread 4 is drawn out of the spinning device 3 with the aid of a draw-off device consisting of two delivery rollers 5 and is delivered to a winding device 6, where the thread 4 is wound onto a bobbin 7 with the aid of a thread guide 11. The winding device 6 includes, for this purpose, a drive 8, which drives the bobbin in its regular direction of rotation DR (see arrow) during the regular operation represented here. The direction of rotation DR as well as the regular draw-off direction AR of the thread 4 are indicated with the aid of arrows. Between the delivery rollers 5 and the winding device 6, the thread 4 can pass through even further units. For example, a waxing unit 13 is also provided in this case.

[0027] In deviation from the representation shown here, in which the textile machine 1 is designed as a spinning machine, it is also possible, of course, that the textile machine 1 is a winder. In this case, the workstation 2 does not comprise a spinning device 3, but rather only a delivery bobbin, from which the thread 4 is drawn and is then supplied to the winding device 6, as described.

[0028] Moreover, the workstation 2 of the textile machine 1 shown here is designed as a so-called autonomous workstation 2 and includes a workstation-specific piecing unit 12, a workstation-specific suction nozzle 10, and a workstation-specific feeder unit 9, with the aid of which, after an interruption of production, the thread 4 can be accommodated by the suction nozzle 10 and presented to the workstation-specific piecing unit 12 in the form of a thread loop 4b (see FIGS. 3 and 4). The suction nozzle 10 is connected to a vacuum duct 14 in the usual way in this case and can be acted upon with vacuum via the vacuum duct 14 in order seek a thread end 4a on the surface of the bobbin 7 (see FIG. 2), which is run onto the bobbin 7, after an interruption of the spinning process or production.

[0029] According to the present representation, the suction nozzle 10 is situated at the workstation 2 in a stationary manner. During production, the thread 4 therefore passes through the suction nozzle 10, which the thread 4 enters at an opening 16 and which the thread 4 exits once again through the opening 19. Alternatively, it would also be conceivable, however, to allow the thread to extend outside the suction nozzle 10 in the known way and to then movably situate the suction nozzle 10 at the workstation 2 in order to be able to move the suction nozzle 10 toward the bobbin 7 in order to seek the thread end 4a.

[0030] The feeder unit 9 is provided for accommodating the thread 4 with the aid of a thread holder 17 and is pivotably situated at the workstation 2, as indicated by the arrow and the position of the feeder unit 9 indicated with the aid of a dashed line. Finally, the textile machine 1 also comprises a controller 15, with the aid of which at least the drive 8 and the feeder unit 9 can be controlled. The controller 15 can be provided, in this case, as a workstation-specific controller 15 as well as a central controller 15 of the textile machine 1. It is also possible that the controller 15 is provided as a group controller for multiple workstations 2.

[0031] Now that the textile machine 1 and the workstation 2 of the textile machine 1, including their units, have been described, the further method for piecing and forming a thread loop 4b will be explained with reference to FIGS. 2 to 4. The same reference characters will be utilized, in this case, for features which are identical or at least comparable to the exemplary embodiment represented in FIG. 1. Provided these features are not explained in detail once again, their design and mode of operation correspond to the design and mode of operation of the features already described above.

[0032] FIG. 2 shows the workstation 2 of the textile machine 1 in a situation in which production has been interrupted and an end 4a of the thread 4 is run onto the bobbin 7. The thread end 4a has therefore to be sought on the surface of the bobbin 7, for the purpose of which a vacuum is applied to the suction nozzle 10 and the bobbin 7 is driven by the drive 8 in the direction of reverse rotation RR (see arrow above the bobbin 7). The feeder unit 9 has already been pivoted out of its resting position or piecing position, which is shown in FIG. 1, into its thread receiving position which is represented in FIG. 2. The feeder unit 9 therefore extends, via its thread holder 17, into the cross-section of the suction nozzle 10, and so the thread 4 is not only sucked into the suction nozzle 10, it also simultaneously enters the thread holder 17 of the feeder unit 9. In the representation shown in FIG. 2, the thread therefore extends from the bobbin 7, via the opening 19 of the suction nozzle 10, through the thread holder 17 of the feeder unit 9 and is held by the suction force, which prevails within the suction nozzle 10. The thread end 4a has already been sucked into the suction nozzle 10 in this case.

[0033] FIG. 3 shows the workstation 2 of the textile machine 1 in one further situation, in which the formation of the thread loop 4b from the sucked-in end 4a of the thread 4 has already started. For this purpose, the feeder unit 9 with the thread 4 accommodated in the thread holder 17 is pivoted from the thread receiving position shown in FIG. 2 back in the direction of the piecing position, as indicated by the arrow. As is clear from the representation, an additional thread length FL, which is indicated in this case with the aid of a dotted line, is required in order to form the thread loop 4b. In contrast to the related art, the additional thread length FL is not drawn from the suction nozzle 10 once again. Instead, the additional thread length FL is made available from the winding device 6. For this purpose, the bobbin 7 is driven by the drive 8 in the direction of reverse rotation RR (see arrow above the bobbin 7). As compared to the related art, only a shorter length of the thread end 4a has to be drawn into the suction nozzle 10, which is just sufficient for holding the thread end 4a with the aid of the vacuum prevailing in the suction nozzle 10.

[0034] In particular, however, due to the return of the thread length FL from the bobbin 7 required for forming the thread loop 4b, it is possible to provide the thread length FL required specifically in this moment at any point in time of the feed movement of the feeder unit 9. For this purpose, the reverse rotation speed of the bobbin 7 is coordinated with the movement of the feed unit 9 in such a way that the thread length returned from the bobbin 7 always behaves synchronously to the thread length FL required for forming the thread loop 4b. In other words, a surplus of thread length does not arise at any point in time, which would possibly twist and could interfere with the subsequent piecing process. In addition, due to the synchronous coordination of the delivered thread length with the presently required thread length FL, an increased thread tension also does not arise at any point in time, which could otherwise cause the thread end 4a prepared for piecing to spring back, or could result in a thread end 4a which is too short. The risk of further thread breaks can also be reduced as a result.

[0035] It can also be advantageous, however, to always return a slightly shorter thread length from the bobbin than is specifically required for forming the thread loop. As a result, a surplus of thread length does not arise, which could twist or result in so-called backloops, and the thread can always be held under tension during the rewinding. In this case, the thread tensile force should be greater than the adhesiveness of the thread on the bobbin. As a result, the thread can no longer become caught on the bobbin. Instead, the thread is always cleanly unwound and returned.

[0036] Finally, FIG. 4 shows yet another workstation 2 of the textile machine 1 in a further situation, in which the formation of the thread loop 4b is nearly complete and the thread loop 4b is delivered to the piecing unit 12 for piecing. For this purpose, the feeder unit 9 is brought back into the piecing position, which is also shown in FIG. 1. Moreover, FIG. 4 shows, once again, the thread length FL, which has accumulated up to this point in time and is required for forming the thread loop 4b.

[0037] The thread loop 4b is then severed in a known way by the piecing unit 12, and so a new thread end 4a arises, which is prepared to be pieced again or to be pieced and is returned into the spinning device 3, where it is pieced once again. Provided the textile machine 1 is designed as a winder, the newly arisen thread end 4a is therefore moved toward a splicing device, where it is connected once again to a further thread end 4a which comes from the delivery bobbin. The original thread end 4a, which has now been separated, is then disposed of via the suction nozzle 10 and the vacuum duct 14.

[0038] In order to coordinate the reverse rotation speed of the bobbin 7 with the feed movement of the feeder unit 9, it is possible, for example, to specify a speed profile for the drive 8, which the drive 8 follows during the feed movement of the feeder unit 9. As a result, acceleration and braking times as well as a movement of the feeder unit 9, which is non-uniform with respect to the thread length FL can be taken into account and appropriately compensated for and, therefore, the thread tensile force can be held largely constant.

[0039] A particularly precise coordination and a delivery of the thread length returned from the bobbin 7 synchronously to the thread length FL required for forming the thread loop 4b are possible, however, when the thread tensile force in the sucked-in thread 4 is measured and the reverse rotation speed of the drive 8 is regulated in such a way that the thread tensile force is largely constant. For this purpose, a measuring unit 18 is provided at the workstation 2, specifically at the suction nozzle 10 in this case (see FIGS. 3 and 4), over which the thread 4 is guided during the formation of the thread loop 4b, and so the tensile force can be measured. The measuring unit 18 is also connected in a signal-transmitting manner to the controller 15 in order to control and regulate the reverse rotation speed of the bobbin 7. The measurement of the thread tensile force can be provided in addition to the control of the drive 8 according to a speed profile in order to improve the accuracy of the coordination of the reverse rotation speed with the feed movement of the feeder unit 9. It is also possible, however, to regulate the reverse rotation speed of the drive 8 only according to the thread tensile force of the thread 4.

[0040] The present invention is not limited to the represented and described exemplary embodiments. The method was described, in this case, with respect to a textile machine 1, which comprises autonomously designed workstations 2 including at least one workstation-specific drive 8 and one workstation-specific feed unit 9. The described method can be utilized particularly advantageously on such a textile machine 1. It is also possible, however, that the drive 8 and the feeder unit 9 are situated on a displaceable maintenance unit of the textile machine 1.

[0041] Further modifications and combinations within the scope of the patent claims are also possible, as is a combination of the features, even if they are represented and described in different exemplary embodiments.

LIST OF REFERENCE CHARACTERS

[0042] 1 textile machine [0043] 2 workstation [0044] 3 spinning device [0045] 4 thread [0046] 4a end of the thread [0047] 4b thread loop [0048] 5 delivery roller [0049] 6 winding device [0050] 7 bobbin [0051] 8 drive of the bobbin [0052] 9 feeder unit [0053] 10 suction nozzle [0054] 11 thread guide [0055] 12 piecing unit [0056] 13 waxing unit [0057] 14 vacuum duct [0058] 15 controller [0059] 16 opening of the suction nozzle [0060] 17 thread holder [0061] 18 measuring unit [0062] 19 opening [0063] AR draw-off direction [0064] DR regular direction of rotation [0065] RR direction of reverse rotation [0066] FL required thread length for forming the thread loop