Title of Invention

A PROCESS AND AN ARRANGEMENT FOR RE-STARTING AN INTERRUPTED SPINNING PROCESS

Abstract

A process and an arrangement for re-starting an interrupted spinning process in a spinning arrangement comprising an air-jet aggregate and a drafting unit is described. In this process, a prepared end of a thread already spun is positioned in the area of a delivery roller pair of the drafting unit. This thread is subsequently transported in the spinning direction and joined by means of a piecing process during this transport to a staple fibre strand fed thereto by the drafting unit. The piecing process takes place dependent on the position of the thread end. During the piecing process, the staple fibre strand and the thread each have a constant transport speed which is lower than the operational speed.

Full Text

BACKGROUND AND SUMMARY OF THE INVENTION A process and an arrangement for re-starting an interrupted spinning process The present invention relates to a process for re-starting an interrupted spinning process in a spinning arrangement comprising an air-jet aggregate and a drafting unit, whereby a prepared end of a thread already spun is positioned in the area of a delivery roller pair of the drafting unit, thereafter transported in spinning direction and joined by means of a piecing process to a staple fibre strand fed thereto by the drafting unit, whereby the piecing process is controlled in dependence on the position of the thread end. The present invention relates further to a spinning arrangement comprising an air-jet aggregate and a drafting unit for re-starting an interrupted spinning process by means of piecing a thread end to a drafted staple fibre strand, comprising a delivery roller pair bordering the drafting zone of a drafting unit, to which delivery roller pair a first drive motor is arranged, comprising further drafting unit roller pairs arranged upstream of the above mentioned delivery roller pair, to which further drafting roller pairs a joint second drive motor is arranged, also comprising means for opening and closing the delivery roller pair, also comprising a sensor for detecting a prepared end of an already spun thread which has been placed in the opened delivery roller pair and subsequently transported in spinning direction by the delivery roller pair which is now closed again, and also comprising controlling means connected with the sensor and the second drive motor. A process and an arrangement of this type are prior art in European published patent application 12 19 737. In this publication, an improvement at the piecing point by means of drafting control is primarily involved, whereby a monitoring of the thread end by a sensor and control of the feed take place in dependence thereon. One drive at least must hereby be accelerated in the piecing phase. The piecing process itself takes place either at operational speed or in the acceleration phase of both drive motors. Both are disadvantageous with regard to consistency. When the piecing process takes place at operational speed, the transport speeds of the thread and of the staple fibre strand are so high that little time remains for a delicate controlling of the process. When, on the other hand, the piecing process takes place during the acceleration process of both drive motors, there is dependency, with regard to the consistency, on the tolerances or on the slip of the transport rollers. It is an object of the present invention to make the piecing process more consistent while retaining the advantages of the known process and the known arrangement. This object has been achieved in accordance with the present invention in that during the piecing process, the staple fibre strand and the thread have, in relation to the operational speed, a reduced and constant transport speed. With regard to the arrangement the object is achieved in that in the moment of piecing of the thread end to the staple fibre strand, the first drive motor and the second drive motor both run at reduced and constant piecing speeds in comparison to their operational speeds. Because the piecing process now takes place at a reduced transport speed in relation to the operational speed, a longer period of time is now available for the actual piecing. Furthermore, because the piecing speed is constant, there is less dependency on tolerances or slip. The entire piecing process can now take place at a more controlled pace. During the piecing process, the staple fibre strand as well as the thread is transported by the delivery roller pair. The position of the thread end can hereby be detected by a sensor, which is, via a control means, connected to a drive for feeding the staple fibre strand. The sensor gives the starting signal for the delayed feed. In an embodiment and a variation of the invention it can be provided that the first part of the fed staple fibre strand can be removed as trash, before the staple fibre strand is connected to the thread end by the piecing process. The fibres of the staple fibre strand coming from the delivery roller pair are, for the purpose of the invention, first deflected by means of a type of fibre stream deflection, whereby this process can take place upstream of the air-jet aggregate or inside the air-jet aggregate. This deflection can be mechanical or pneumatic. The fibre stream of the staple fibre strand, after a certain delay in time, can be switched back to its original course and the air-jet aggregate put into operation again by means of a supply of spinning pressure when the end of the thread is recognized by the sensor, or when caused to do so by a time control device. In the case of such a fibre stream deflection, there is no dependency on the acceleration behaviour of the first and second drive motors and thus very short piecing places can be realized. In a further embodiment of the present invention it can be provided that directly after the piecing process the fed fibre amount is increased for a short time in order to compensate thin thread places. This can be easily controlled by the second drive motor. With regard to the arrangement it can be provided that the first drive motor is not only arranged to the delivery roller pair, but also at the same time to a withdrawal roller pair that withdraws the thread from the air-jet aggregate. The withdrawal roller pair hereby naturally maintains a transport speed which ensures a certain tension. It can be advantageous to arrange a thread reservoir downstream of the withdrawal roller pair, said thread reservoir taking up a thread loop and being effective during the run-up of the first drive motor to the piecing speed, which thread reservoir is evacuable during the constant piecing speed phase. This variation is based on the knowledge that the winding device arranged downstream of the withdrawal roller pair has, as a rule, a relatively large crosswound bobbin to move and that because of this, a certain degree of slip of the thread can occur in the area of the crosswound bobbin during the acceleration phase of the individual drive motors, which then leads temporarily to a thread loop between the withdrawal roller pair and the winding device. This thread loop can be monitored in the thread reservoir and reduced again during the constant transport speed in the piecing phase. When the variations with the fibre current deflection are chosen, it is possible that the first drive motor and the second drive motor start up at the same time and the deflecting device, dependent on the position of the end of the detected thread, is rendered ineffective again. It can hereby be provided that the first drive motor and the second drive motor maintain a constant speed ratio to one another from the starting point onwards, which already corresponds to the speed ratio during operation. BRIEF DESCRIPTION OF THF ACCOMPANYING DRAWINGS These and further objects, features and advantages of the present invention will become more readily apparent from the following detailed description thereof when taken in conjunction with the accompanying drawings wherein: Figure 1 is a schematic representation of a spinning arrangement on which the process according to the present invention for re-starting an interrupted spinning process is carried out, Figures 2,3 and 4 show the preparation of an end of an already spun thread for a subsequent piecing process, Figure 5 is a section of Figure 1 with an additional device according to the present invention for a fibre stream deflection, Figure 6 is a diagram demonstrating a piecing process to be carried out according to Figure 1, Figure 7 is a similar diagram demonstrating a piecing process to be carried out according to Figure 5. DETAILED DESCRIPTION OF THE DRAWINGS The spinning arrangement according to Figure 1 serves the spinning of a thread 1 from a staple fibre strand 2. The spinning arrangement comprises as essential component parts an air-jet aggregate 3, which, for example, can be designed according to the above mentioned European published patent application 12 19 737, said spinning arrangement also comprising a drafting unit 4 designed preferably as a three-cylinder drafting unit, also comprising a withdrawal roller pair 5 as well as a winding device 6. The drafting unit 4 shown comprises a front roller pair 7, to which the staple fibre strand 2 is fed in feed direction A, furthermore an apron roller pair 8, which is looped in a known way by guiding aprons 9 and 10, and comprising a delivery roller pair 11, at which the drafting zone 29 of the drafting unit 4 ends. A staple fibre strand 2 is drafted in the known way in the drafting unit 4 to the desired degree of fineness. The delivery roller pair 11 comprises a driven bottom roller 32 as well as a pressure roller 12 and is connected to devices 13 for opening and closing the delivery roller pair 11. The open position of the pressure roller 12 is denoted by a broken line at 12'. The air-jet aggregate 3 comprises a feed channel 33, to which the drafted, but as yet twist-free staple fibre strand 2 is fed for receiving its spinning twist. The air-jet aggregate 3 comprises further a yarn withdrawal channel 14 for the spun yarn 1. In the inside of the air-jet aggregate 3, compressed air jets 15 are arranged, whose outlet openings lead into a vortex chamber 16, in which the actual twist application takes place, as, for example, is described in the above mentioned European published patent application 12 19 737. The yarn withdrawal channel 14 is hereby located in a stationary, spindle-like component 17. The spinning direction is denoted by the letter B. Between the air-jet aggregate 3 and the withdrawal roller pair 5, an end-break detector 18 is arranged, whose function is described below. Downstream of the withdrawal roller pair 5 the winding device 6 is arranged, which comprises a take-up roller 21, by means of which during operation a crosswound bobbin 22 is driven by friction, onto which the spun yarn 1 is wound. This is supported by a traversing device (not shown) for the yarn 1 which is located directly upstream of the take-up roller 21. When the spinning arrangement is started up and accelerated from a standstill, it can happen, when the crosswound bobbin 22 has reached a certain volume, that the momentary transport speed of the thread 1 is somewhat lower there than at the withdrawal roller pair 5 due to the slip at the take-up roller 21. In this case, a yarn loop 20 forms during the acceleration phase, which is then temporarily taken up in a yarn reservoir 19. As during operation the take-up roller 21 is driven at a very slightly higher speed than the yarn 1 withdrawn by the withdrawal roller pair 5 in withdrawal direction C, the loop 20 can straighten out again during operation or during a phase of constant transport of the yarn 1. A first drive motor 23 is provided for the drive of the delivery roller pair 11 as well as for the withdrawal roller pair 5, so that these roller pairs 11,5 are always jointly driven, however at very slightly differing speeds, which ensures a desired tension of the yarn 1. The front roller pair 7 and the apron roller pair 8 of the drafting unit 4 is driven by a joint second drive motor 24. That the apron roller pair 8 must rotate significantly faster than the front roller pair 7 should be taken into consideration here, as in this area the pre-draft of the staple fibre strand 2 takes place. A separate drive motor 25 for the take-up roller 21 is provided. For the following description of the two-stage start-up of the second drive motor 24, a control device 26 is provided, for the first drive motor 23 and the motor 25 a further control system 28 is provided. These will be described in more detail below. The control device 26 is connected to the second drive motor 24 and the end-break detector 18, while the other control system 28 is connected to the first drive motor 23, the drive motor 25 and the end-break detector 18. In addition there is in the area of the delivery roller pair 11 a sensor 27 (to be described below), which sensor 27 is also connected electrically to the control device 26. The control device 26 and the control system 28 control the drive motors 23,24 and 25 connected thereto in such a way that they start up in two stages, that is, initially to a constant intermediate speed and subsequently to their operational speed. Certain circumstances, for example an end break, cause the normal spinning process to be interrupted. In such a case, the interrupted spinning process must be re-started. In order that, in the case of an end break, no further staple fibre strand 2 is fed to the drafting unit 4 and the take-up roller 21 does not continue to turn unnecessarily, which would unnecessarily press in the thread layer on the crosswound bobbin 22, it is provided - controlled by the end break detector 18 - that via the control device 26 and the control system 28 the first drive motor 23 as well as the second drive motor 24 and the motor 25 for the take-up roller 21 are brought to a standstill. The sequence is such that the staple fibre strand 2 between the front roller pair 7 and the apron roller pair 8 does not tear, but rather remains threaded into the respective nipping points, and that the staple fibre strand 2, however, between the guiding aprons 9,10 and the delivery roller pair 11 does tear. In order to start up the spinning arrangement again, a piece of the already spun thread 1, denoted here by the reference number 31, must be manually or automatically moved a short distance through the air-jet aggregate 3 so that the end 30 of the thread 31 to be pieced can be reconnected to the staple fibre strand 2 still located in the drafting unit 4. The end 30 is hereby prepared for the piecing process, that is cut off and opened to a kind of fibre brush, which facilitates the piecing process. In order to feed back this thread 31, the pressure roller 12 of the delivery roller pair 11 can be opened by means of the device 13 into the position 12'. The subsequent process for re-starting the spinning process is described in more detail below with the aid of Figures 6 and 7. It need only be said at this point that during the piecing process, the staple fibre strand 2 and the thread 1 have, in relation to the operational speed, a reduced and constant transport speed. Firstly a description of the preparation of the end 30 of the thread 31 is given with the aid of Figures 2. 3 and 4: According to Figure 2. first of all the pressure roller 12 (shown in Fig. 1) is raised from the bottom roller 32 into the position 12'. At the same time, the feed channel 33 (shown in Fig.1) is swivelled into the position 33'. After the area of the vortex chamber 16 and other components of the air-jet aggregate 3 have been cleaned, the thread 31 to be pieced is then transported back into the shown position and cut off to a suitable length L for the purposes of the piecing process. In addition, the end 30 of the thread 31 is opened to form a thread brush with means not shown. These advantageous measures for the piecing process are not part of the present invention. At this point in time, all rollers, that is the front roller pair 7, the apron roller pair 8 and naturally also the delivery roller pair 11. the withdrawal roller pair 5 as well as the take-up roller 21 are at a standstill. The first piece 34 of the broken off staple fibre strand 2 projects out from the guiding aprons 9, 10. where the end -break took place. According to Figure 3, the thread 31 prepared for the piecing process is now fed back through the sensor 27,so that the sensor 27 is located between the end 30 of the thread 31 and the delivery roller pair 11 which is closed again. The first drive motor 23 and also the motor 25 for the take-up roller 21 (shown in Fig. 1) can now be started up via the control system 28 (shown in Fig. 1). The motors 23 and 25 are accelerated however only up to the above mentioned intermediary speed and then held constant for a pre-determincd length of time at this speed. The motor 24 for the front roller pair 7 and the apron roller pair 8 remains at this point at a standstill. When the end 30 of the thread 31 has passed the sensor 27 as shown in Figure 4. the second drive motor 24 (shown in Fig. 1) is switched on via the control device 26 (shown in Fig. 1) after a short delay, so that the first piece 34 of the staple fibre strand 2 is again fed to the delivery roller pair 11. The second motor 24 is also held at a constant intermediary speed. The control system is so designed, that the end 30 of the thread 31 touches the staple fibre strand 2 in the area of the nipping point of the delivery roller pair II and is pieced together therewith. Only then is the first drive motor 23. the second drive motor 24 as well as the motor 25 for the take-up roller 21 driven up to operational speed by means of the control device 26 and the control system 28. The piecing process is carried in such a way that during piecing, the staple fibre strand 2 and the thread 31 (corresponds to the thread 1 during operation) have, in relation to the operational speed, a reduced and constant transport speed. With the aid of the diagram in Figure 6, the piecing process is described in more detail below: On the ordinate the transport speed v is given ( it could also be the number of revolutions of the drive motor) and on the abscisse the time t in connection with the piecing process of an end 30 of the thread 31 to the staple fibre strand 2 is given. The reference number v1, refers to the transport speed of the delivery roller pair 11, the reference number v2 refers to the transport speed of the apron roller pair 8. The additional index A denotes the respective piecing speed, the additional index B the respective operational speed. v1A is thus the transport speed of the delivery roller pair 11 during piecing, v1B is its operational speed. Accordingly, V2A is the piecing speed of the apron roller pair 8, V2B is its speed. It can be seen that the piecing speeds v1A and v2A are reduced but constant in comparison to the operational speeds v1B and v2B. The point at which the end 30 of the thread 31 passes the sensor 27 is denoted by ts. After a short delay, the second drive motor 24 of the drafting unit 4 is started at time t2, so that the first piece 34 of the staple fibre strand 2 can be fed to the thread 31. The length L has been accordingly measured. The point in time tA denotes the moment of the actual piecing. The reduced and constant transport speeds for the fibre strand 2 and the thread 1 or 31 must be reached exactly at the time tA. Below a modification of Figure 1 is shown with the aid of Figure 5: According to Figure 5, there is a particular form of piecing in which the fibre current of the re-fed staple fibre strand 2 coming from the delivery pair 11 is at first fed as trash 36 in suction direction D as a fibre current deflection to suction tube 35, or is deflected by other means. This suction tube 35 can be located between the delivery roller pair 11 and the feed channel 33, or alternatively, as shown by a broken line and 35' and D', inside the air-jet aggregate 3. When the end 30 of the thread 31 is recognized by the sensor 27, or is alternatively controlled by a time control device, the deflected fibre current is no longer deflected after a certain time delay and the air-jet aggregate 3 is made operational again by switching on the compressed air stream. Because of the fibre current deflection, there is no dependency on the acceleration pattern of the second drive motor 24 any more and thus very short piecing times can be realized. This modification according to Figure 5 is explained below with the aid of the diagram in Figure 7: Here the transport speed v is also given on the time t. As already explained in Figure 6, the index 1 refers respectively to the delivery roller pair 11, while the index 2 refers respectively to the apron roller pair 8. The index A refers to the transport speed during piecing, the index B to the transport speed during normal operation. With the aid of Figure 7, it can be seen that in the case of the explained modification the first drive motor 23 and the second drive motor 24 could be started up at the same time. Controlled hereby, either by the sensor 27 or another control device, is the moment of the end of the fibre current deflection, namely that the fibre current is no longer removed as trash 36, but rather joined up with the end 30 of the thread 31. In Figure 7 a curve 37 is shown after the piecing time tA, which illustrates a thin place compensation. Thus it is possible, directly after the piecing process, to increase the speed of the second drive motor 24 for a short time before it is finally driven to its operational speed v2B. WE CLAIM: 1. A process for restarting an interrupted spinning process in a spinning arrangement comprising an air-jet aggregate (3) and a drafting unit (4), whereby a prepared end of a thread already spun is positioned in the area of a delivery roller pair (11) of the drafting unit (4), thereafter transported in spinning direction and joined by means of a piecing process to a staple fibre strand (2) fed thereto by the drafting unit (4), whereby the piecing process is controlled in dependence on the position of the thread end, characterized in that, during the piecing process, the staple fibre strand (2) and the thread (31) have in relation to the normal operational speed a reduced and constant transport speed. 2. A process according to claim 1, wherein the staple fibre strand and the thread are transported by the delivery roller pair during the piecing process. 3. A process according to claim 1 or 2, wherein the position of the end of the thread is detected by a sensor, which is connected via control means to a drive for feeding the staple fibre strand. 4. A process according to any one of the claims 1 to 3, wherein the first part of the fed staple fibre strand is drawn off as trash before the staple fibre strand is joined to the end of the thread by the piecing process. 5. A process according to claim 4, wherein the staple fibre strand is temporarily removed as trash between the delivery roller pair and the air-jet aggregate. 6. A process according to claim 4, wherein the staple fibre strand is temporarily drawn off as trash in the air-jet aggregate. 7. A process according to any one of the claims 4 to 6, wherein - preferably by means of detection of the position of the end of the thread by a sensor - the removal as trash ends, causing the operational spinning process to be re-started. 8. A process according to any one of the claims 1 to 7, wherein directly after the piecing process, the fed amount of fibres is increased for a short time to balance out thin thread places. 9. A spinning arrangement comprising an air-jet aggregate (3) and a drafting unit (4) for restarting an interrupted spinning process by means of piecing a thread end to a drafted staple fibre strand, comprising a delivery roller pair (11) bordering the drafting zone (29) of a drafting unit (4) to which delivery roller pair a first drive motor (23) is arranged, comprising further drafting unit roller pairs arranged upstream of the above mentioned delivery roller pair, to which further drafting roller pairs a joint second drive motor (24) is arranged, also comprising means (13) for opening and closing the delivery roller pair (11) also comprising a sensor for detecting a prepared end of an already spun thread which has been placed in the opened delivery roller pair and subsequently transported in spinning direction by the delivery roller pair which is now closed again, and also comprising controlling means (26) connected with the sensor (27) and the second drive motor, characterized in that, in the moment of piecing of the end (30) of the thread (31) to the staple fibre strand (2), the first drive motor (23) and the second drive motor (24) run at reduced and constant speeds in relation to their operational speeds. 10. An arrangement according to claim 9, wherein the first drive motor (23) additionally to the delivery roller pair (11) is at the same time arranged to a withdrawal roller pair (5) which removes the spun thread (1) from the air-jet aggregate (3). 11. An arrangement according to claim 10, wherein a yarn reservoir (19) is arranged downstream of the withdrawal roller pair (5) during the start-up of the first drive motor (23) to the piecing speed, which yarn reservoir (19) takes up a yarn loop (20), and which yarn reservoir (19) can be emptied during the phase of the constant piecing speed. 12. An arrangement according to any one of claims 9 to 11, wherein a deflecting device (35) for removing the transported staple fibre strand (2) temporarily as trash (36) is arranged to the delivery roller pair (11). 13. An arrangement according to any one of claims 9 to 12, wherein the start-up of the second drive motor (24), in dependence on the position of the end (30) of the detected thread (31), is delayed in relation to the start-up of the first drive motor (23). 14. An arrangement according to claim 12, wherein the first drive motor (23) and the second drive motor (24) start-up simultaneously and the deflecting device (35), in dependence on the position of the end (30) of the detected thread (31), becomes ineffective, 15. An arrangement according to claim 14, wherein, from the first moment of the start-up, both the first drive motor (23) and the second drive motor (24) have a continuous and constant speed ratio. A process and an arrangement for re-starting an interrupted spinning process in a spinning arrangement comprising an air-jet aggregate and a drafting unit is described. In this process, a prepared end of a thread already spun is positioned in the area of a delivery roller pair of the drafting unit. This thread is subsequently transported in the spinning direction and joined by means of a piecing process during this transport to a staple fibre strand fed thereto by the drafting unit. The piecing process takes place dependent on the position of the thread end. During the piecing process, the staple fibre strand and the thread each have a constant transport speed which is lower than the operational speed.

Documents:

435-KOL-2004-FORM-27.pdf

435-kol-2004-granted-abstract.pdf

435-kol-2004-granted-claims.pdf

435-kol-2004-granted-correspondence.pdf

435-kol-2004-granted-description (complete).pdf

435-kol-2004-granted-drawings.pdf

435-kol-2004-granted-examination report.pdf

435-kol-2004-granted-form 1.pdf

435-kol-2004-granted-form 18.pdf

435-kol-2004-granted-form 2.pdf

435-kol-2004-granted-form 3.pdf

435-kol-2004-granted-form 5.pdf

435-kol-2004-granted-pa.pdf

435-kol-2004-granted-priority document.pdf

435-kol-2004-granted-reply to examination report.pdf

435-kol-2004-granted-specification.pdf

435-kol-2004-granted-translated copy of priority document.pdf

435-KOL-2004-PRIORITY DOCUMENT 1.1.pdf