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(11) | EP 3 992 336 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A SPINNING STATION OF A ROTOR SPINNING MACHINE WITH AN IMPROVED YARN TAKE-UP DEVICE, ROTOR SPINNING MACHINE AND RELATED SPINNING METHOD |
| (57) A spinning station (30) of a rotor spinning machine comprising: - a sliver feeding mechanism (21), an opening mechanism (22), a spinning rotor (19) producing a yarn from said sliver, - a yarn take-up device (6) comprising a take-up roller (11) and a pressing roller (12) cooperating each other with the yarn coming from said spinning rotor (19), - a winding mechanism (14) comprising a winding roller (13) and a package (15) so as to wind said yarn on said package (15), - said yarn take-up device (6) intercepting the yarn (5) and comprising a tube (4) able to house and accumulate at least partially said yarn (5), - a control unit (25) operatively connected with said yarn take-up mechanism (6), with said sliver feeding mechanism (21) and with said winding mechanism (14), the control unit (25) being programmed so that - during spinning, the yarn take-up device (6) sucks at least partially a portion of the yarn (5) within said tube (4), in order to control the loosening of the yarn (5) during spinning and then gradually releases it back for winding, wherein the yarn take-up device (6) contains an air injector (1) to create a negative pressure (9) within said tube by means of compressed air (8), so as to suck said yarn (5). |
FIELD OF APPLICATION
[0001] The present invention relates to a spinning station of a rotor spinning machine with an improved yarn take-up device, a rotor spinning machine and a method for taking-up a yarn.
BACKGROUND ART
[0002] As known, in order to obtain a uniform yarn quality on a rotor spinning machine, it is necessary to sufficiently synchronize the beginning of the yarn take-up from the beginning of the yarn winding and thus eliminate the possibility of different yarn take-up times in the rotor. Current prior art solutions do not allow such a synchronization so it is necessary to create a small separation between the beginning of the yarn take-up and the beginning of the yarn winding.
[0003] However, in order to separate the beginning of the yarn take-up from the beginning of the yarn winding, it is necessary to create an additional device for the take-up of the yarn being formed in the meantime.
[0004] At the same time, in order to achieve a uniform yarn spinning time in the rotor, it is necessary to reduce as much as possible the transients of yarn take up and yarn piecing phases.
PRESENTATION OF THE INVENTION
[0006] The need is therefore felt to solve the drawbacks and limitations mentioned in reference to the prior art.
[0007] Such a need is satisfied by a spinning station of a rotor spinning machine with an improved yarn take-up device according to claim 1, by a rotor spinning machine according to claim 11 and by a related spinning method according to claim 12.
DESCRIPTION OF THE DRAWINGS
[0008] Further features and advantages of the present invention will become more comprehensible from the following description of preferred and non-limiting embodiments thereof, in which:
figure 1 shows a side view of a spinning station comprising a yarn take-up device according to a possible embodiment of the present invention;
figure 2 shows a front view of detail II shown in figure 1;
figure 3 shows a side view of a spinning station comprising a yarn take-up device according to another possible embodiment of the present invention;
figure 4 shows a front view of detail IV shown in figure 3.
[0009] The elements or parts of elements common to the embodiments described below will be indicated using the same reference numerals.
DETAILED DESCRIPTION
[0010] With reference to the aforesaid drawings, a spinning station is indicated as a whole with 30.
[0012] In any case, for the purposes of the present invention, the spinning station 30 and the rotor spinning machine may be of any type, shape and size.
[0013] The spinning station 30 comprises a sliver feeding mechanism 21, an opening mechanism 22, a spinning rotor 19 producing a yarn 5 from said sliver.
[0014] Moreover, the spinning station 30 comprises a yarn take-up device 6 comprising a take-up roller 11 and a pressing roller 12 cooperating each other with the yarn 5 coming from said spinning rotor 19.
[0015] The spinning station 30 comprises moreover a winding mechanism comprising a winding roller 13 and a package 15 so as to wind said yarn on said package 15.
[0016] The yarn take-up device 6 intercepts the yarn 5 and comprises a tube 4 (or suction throat 4) able to house and accumulate at least partially said yarn 5.
[0017] The spinning station 30 comprises a control unit 25 operatively connected with said yarn take-up mechanism 6, with said sliver feeding mechanism 21 and with said winding mechanism 14.
[0018] Advantageously, the control unit 25 is programmed so that during spinning and/or piecing cycle, the yarn take-up device 6 sucks at least partially a portion of the yarn within said tube 4, in order to control the loosening of the yarn 5 during spinning and then gradually releases it back for winding.
[0019] In particular, the yarn take-up device 6 contains an air injector 1 to create a negative pressure 9 within said tube 4 by means of compressed air 8, so as to suck said yarn 5.
[0020] According to a possible embodiment, the yarn take-up device 6 sucks at least partially a portion of the yarn 5 within said tube 4, when the yarn 5 is running.
[0021] According to a possible embodiment, the spinning station 30 comprises a compressed air system which is operatively connected both to the yarn take-up device 6 and to a pressure device 16 (typically an arm) acting on said winding roller 13 and/or package 15 so as to modify the contact pressure between them.
[0022] Preferably, the control unit 25, by means of said compressed air system, modifies the pressure contact between the winding roller 13 and the package 15 in relation to the loosening of the yarn 5 and the length of yarn 5 intercepted by the yarn take-up device 6.
[0023] According to a possible embodiment, said compressed air system has a nozzle 3 of the injector 1 with an adjustable diameter.
[0024] According to a possible embodiment, the nozzle 3 of the injector 1 has exchangeable shape variants.
[0025] According to a possible embodiment, the flow of compressed air 8 into the nozzle 3 is not continuous.
[0026] According to a possible embodiment, the control unit 25 is programmed so that the switching on and off of the compressed air 8 is controlled at each location of the machine individually, in parts or simultaneously.
[0027] According to a possible embodiment, the control unit is programmed so that at a time before the winding of the yarn 5 on the package 15, i.e. when the package 15 is not yet in contact with the winding roller 13, the yarn take-up device 6 temporarily takes-up the yarn 5 and then gradually releases it for winding.
[0028] The functioning of the yarn take-up device according to the present invention will now be described.
[0029] In particular, by means of compressed air [8], which passes through the nozzle 3 of exchangeable cross-section into the diffuser 2, a negative pressure 9 is created in the suction nozzle or tube 4, which is located near the yarn spinning axis and at a time when the yarn take-up is stopped, i.e. the pressure roller 12 is not in contact with the take-up roller 11, it helps to get the yarn 23 evenly from the yarn base pin 24 to the spinning axis, and thus evenly the yarn end 20 gets to the rotor 19 for piecing, on condition that the suction of the yarn take-up device 6 is modulated so as not to influence or interfere with the suction of the rotor 19.
[0030] Furthermore, at the time of stopping the winding, i.e. when the package 15 is not yet in contact with the winding roller 13, it can take-up the yarn 5 for a certain time, which it then gradually releases into the winding, so as to ensure uniformity of the piecer and to avoid breaks in the subsequent processing of the yarn 5 from the package 15.
[0031] The suction nozzle or tube 4 has interchangeable shapes that can be replaced as needed to achieve the best take-up of yarn.
[0032] According to a possible embodiment, the compressed air supply 8 is connected via a valve 28 from the control unit 25 of the spinning station 30, which controls it and which can also be connected from the yarn presence sensor 26 for possible adjustment of the start time of this device.
[0033] After ensuring the yarn take-up and achieving the correct yarn tension 7 between the take-up roller 11 and the take-up roller 13, the air supply 8 can be closed, which can be done either by fixed setting the take-up time or by a yarn presence sensor.
[0034] Moreover, this device can also be advantageously used to reduce the loosening of the yarn 5 during winding on the package 15 due to the construction of soft packages or other non-standard packages. It is possible to use full flow with a smaller nozzle 3 or intermittent air flow, which will significantly reduce the demands on compressed air for longer use. The same principle can be used when winding conical packages 15, where periodic loosening occurs due to different package diameters.
[0035] The yarn take-up device 6 can also be used to reduce loosening during stopping and restarting spinning on rotor spinning machines with a controlled stopping and starting function, both with a standard machine power supply and in the event of a power failure. In the time before the spinning stops, a negative pressure is created for the correct tension of the yarn during unwinding on the package. At the time when the compressed air is restored, the yarn can be tensioned again with this device and, if necessary, the excess yarn can be withdrawn for a while and then gradually released to winding before the withdrawal moves back, when the yarn end is introduced into the rotor.
[0036] To reduce the occurrence of loose yarn 60 during shearing, which can cause a spinning break, this device is switched on before the start of shearing and a full or intermittent air flow 8 creates the necessary pressure 9 to suck loose yarn 60 into the suction nozzle or tube 4 of the jet pump (injector) 1 and thus reduces any loosening caused, for example, by greater friction of the yarn on some part of the line or insufficient vacuum in the exhaust pipe of the doffer or the auxiliary exhaust pipe of the machine.
[0037] The activation time of the yarn take-up device is function of different variables including, for example, the yarn count processed, the winding speed, the material of the yarn and so on.
[0038] Moreover, the activation time of the yarn take-up device can be calculated and set by the central processing unit of the machine, automatically or it can be set also manually.
[0039] As may be appreciated by what is described above, the present invention allows the drawbacks introduced in the known art to be overcome.
[0040] In particular, the solution according the invention comprising a yarn take-up device which is switched on before the take-up starts solves the problem of reducing as much as possible the transients of yarn take up and yarn piecing phases.
[0041] Moreover the device also sufficiently solves the problems with unsatisfactory yarn tension during the spinning of soft or otherwise non-standard windings or conical bobbins and thus improves the quality of the winding. Furthermore, it can be advantageously used for automatic doffing.
[0042] Moreover, the device according to the invention can also be advantageously used to reduce the loosening of the yarn during winding on the package due to the construction of soft packages or other non-standard packages. For example, It is possible to use full flow with a smaller nozzle or intermittent air flow, which will significantly reduce the demands on compressed air for longer use. The same principle can be used when winding conical packages, where periodic loosening occurs due to different package diameters.
[0043] The device can also be used to reduce loosening during stopping and restarting spinning on rotor spinning machines with a controlled stopping and starting function, both with a standard machine power supply and in the event of a power failure. In particular, in the time before the spinning stops, a negative pressure is created for the correct tension of the yarn during unwinding on the package. At the time when the compressed air is restored, the yarn can be tensioned again with this device and, if necessary, the excess yarn can be withdrawn for a while and then gradually released to winding before the withdrawal moves back, when the yarn end is introduced into the rotor.
[0044] To reduce the occurrence of loose yarn during shearing, which can cause a spinning break, this device can be switched on before the start of shearing and a full or intermittent air flow creates the necessary pressure to suck loose yarn into the suction nozzle of the jet pump (injector) and thus reduces any loosening caused, for example, by greater friction of the yarn on some part of the line or insufficient vacuum in the exhaust pipe of the doffer or the auxiliary exhaust pipe of the machine.
[0045] The use of a local air injector to create a negative pressure within the tube of the yarn take-up device by means of compressed air, so as to suck said yarn, is a real improvement with respect to the use of a centralised air intake plant of the spinning machine. In fact a local air injector gives the possibility of obtain a precise value of negative pressure in the tube with respect to a centralised solution. In this way the control of the length and of the tension of the yarn is more precise with respect to a solution using the centralised intake system. Moreover in this way there is no possibility to interfere with the functioning of the centralised system and the total air consumption is significantly reduced.
[0046] Advantageously, this device can be used on automatic or semi-automatic machines as a part of a self-contained part of the machine.
[0047] The solution according to the present invention largely eliminates problems with the formation of loose yarn being wound onto a package on rotor fine spinning machines, which can cause problems during further processing, especially in the case of:
- Loosening during or immediately after spinning-in
- Loosening during yarn distribution when it is being wound onto a spool, especially at high draw-off speeds,
- Loosening during doffing due to e.g. increased yarn friction against a contact edge or due to small negative pressure after temporary yarn draw off outside the package,
- Loosening when forming non standard windings, soft windings or conical packages,
- Loosening due to varying technological speeds (feed or draw-off), especially when producing fancy yarns.
[0048] Moreover, the solution provides a reduction of loosening during stopping and starting of a plurality of spinning units and it significantly eliminates the deficiencies in the varying speed of insertion and subsequent removal of the yarn from the rotor during spinning-in.
[0049] A person skilled in the art, with the object of meeting contingent and specific needs, can make several changes and variants to the apparatuses and methods described above, moreover all contained within the scope of the invention, which is defined by the following claims.
LIST of Numeral References
[0050]
- 1.
- Injector, jet pump
- 2.
- Diffuser
- 3.
- Nozzle
- 4.
- Tube or suction throat
- 5.
- Yarn
- 6.
- Yarn take-up device
- 7.
- Correctly tensioned yarn
- 8.
- Compressed air supply
- 9.
- Generated negative pressure
- 10.
- Outlet air
- 11.
- Draw off roller
- 12.
- Pressure roller
- 13.
- Winding roller
- 14.
- Tube
- 15.
- Spool
- 16.
- Pressure device (Arm)
- 17.
- Yarn distribution
- 18.
- Passive compensator
- 19.
- Spinning Rotor
- 20.
- Yarn end for spinning in
- 21.
- Feeding mechanism
- 22.
- Singling out mechanism
- 23.
- Yarn spinning in reserve
- 24.
- Reserve hold pin
- 25.
- Control unit
- 26.
- Yarn presence sensor
- 28.
- Valve
- 30.
- Spinning station
- 60.
- Loose yarn
- a sliver feeding mechanism (21), an opening mechanism (22), a spinning rotor (19) producing a yarn from said sliver,
- a yarn take-up device (6) comprising a take-up roller (11) and a pressing roller (12) cooperating each other with the yarn coming from said spinning rotor (19),
- a winding mechanism (14) comprising a winding roller (13) and a package (15) so as to wind said yarn on said package (15),
- said yarn take-up device (6) intercepting the yarn (5) and comprising a tube (4) able to house and accumulate at least partially said yarn (5),
- a control unit (25) operatively connected with said yarn take-up mechanism (6), with said sliver feeding mechanism (21) and with said winding mechanism (14), the control unit (25) being programmed so that
- during spinning, the yarn take-up device (6) sucks at least partially a portion of the yarn (5) within said tube (4), in order to control the loosening of the yarn (5) during spinning and then gradually releases it back for winding, wherein the yarn take-up device (6) contains an air injector (1) to create a negative pressure (9) within said tube by means of compressed air (8), so as to suck said yarn (5).
- providing a spinning station (30) according to any of the claims from 1 to 10,
- during spinning, sucking at least partially a portion of the yarn (5) within said tube (4) of the yarn take-up device (6), in order to control the loosening of the yarn (5) during spinning and then gradually releasing it back for winding,
- wherein the yarn take-up device (6) contains an air injector (1) to create a negative pressure (9) within said tube by means of compressed air (8), so as to suck at least partially said yarn (5).
- by means of compressed air (8), which passes through the nozzle (3) of exchangeable cross-section into a diffuser (2), creating a negative pressure (9) in the suction nozzle or tube (4), which is located near the yarn spinning axis and at a time when the yarn take-up is stopped, i.e. the pressure roller (12) is not in contact with the take-up roller (11), so as to get the yarn (5) evenly from a yarn base pin (24) to the spinning axis, and thus evenly the yarn end (20) gets to the rotor (19) for piecing.
- at the time of stopping the winding, i.e. when the package (15) is not yet in contact with the winding roller (13), taking-up the yarn (5) for a certain time, and gradually releasing into the winding, so as to ensure uniformity of a piecer and to avoid breaks in the subsequent processing of the yarn (5) from the package (15) .
- reducing the loosening of the yarn (29) during winding on the package (15), due to the construction of soft packages (15), conical packages (15) or other non-standard packages (15), by using full flow with a smaller nozzle (3) or intermittent air flow, which will significantly reduce the demands on compressed air for longer use.
- reducing the loosening of the yarn (5) during stopping and restarting spinning on rotor spinning machines with a controlled stopping and starting function,
wherein the method comprises the steps of:- in the time before the spinning stops, creating a negative pressure if the yarn take-up device (6) for the correct tension of the yarn (5) during unwinding on the package (15),
- at the time when the compressed air is restored, tensioning the yarn (5) again with the yarn take-up device (6) and, if necessary, withdrawing the excess yarn (5) for a while and then gradually releasing to winding before the withdrawal moves back, when the yarn end is introduced into the rotor (19).
- to reduce the occurrence of loose yarn (60) during shearing, which can cause a spinning break, switching on the yarn take-up device (6) before the start of shearing,
- providing a full or intermittent air flow (8) creating the necessary pressure (9) to suck loose yarn (60) into the suction nozzle or tube (4) and thus reducing any loosening of the yarn (5).