Patent Application
20160289868
A method for removing the faulty yarn portion from a work station of an open-end spinning machine after the work station is stopped in a controlled manner, especially after a defect of the spun yarn is detected by a sensor of the quality of yarn.
A device for performing the method at a work station of an open-end spinning machine, whereby each work station of the machine comprises a suction nozzle for sucking the faulty yarn portion after the work station is stopped in a controlled manner.
The production of the spun yarn takes place on spinning machines comprising a plurality of work stations arranged in several substantially parallel rows. During the operation of the machine it is impossible to rule out the possibility that a smaller or greater yarn portion containing defects is spun out. If these defects are visible or if they negatively affect the mechanical properties of yarn, which are essential in the process of further application of yarn, it is necessary to ensure that the defective yarn portion will not get onto the final wound bobbin of the spun yarn. It is therefore necessary to cut out the faulty yarn portion and join the remaining ends of the high-quality yarn. Such joints represent also a local change in yarn diameter, which entails making a compromise so that the new joint will not represent a greater fault of yarn than the fault detected by the sensor.
The operation of a modern open-end spinning machine or the steps carried out by the operator to meet the requirements for yarn quality are known. A spinning machine is at each work station provided with a sensor of yarn quality, the so-called yarn clearer, which monitors the running spun yarn, which means its diameter and its changes, changes of the colour or structure of the yarn, etc. Current sensors of yarn quality are due to high sensitivity able to respond even to minor changes which, however, may occur even on yarn portions of a greater length which have to be removed.
If a change of yarn is detected at a work station of the machine, which is a signal of a possible defect, the process of recording the yarn length is automatically started. If after a certain predetermined period of time the criterion of cleaning the yarn is not exceeded, recording the yarn length is terminated without further intervention. On the other hand, if within this period of time the criterion for cleaning the yarn is exceeded, spinning is automatically terminated at this work station and the total length of the yarn spun between the time of detecting a possible defect and the time when the spinning operation is terminated.
A suction nozzle of a work station is connected to a vacuum system of an open-end spinning machine, whereupon the entire length of the faulty yarn is unwound from the final bobbin, being sucked into the vacuum system of an open-end spinning machine and being deposited in a respective space alloted for waste, whereupon the operator finishes the preparation of yarn for a new spinning-in operation.
The vacuum system of an open-end spinning machine is used to suck in the yarn ends after cutting out the faulty yarn portion or after a yarn breakage, to unwind this portion of the already spun yarn from the final bobbin and to suck it off, or to join the ends of the high-quality yarn by a pneumatic splicer.
Taking into account a great plurality of work stations of an open-end spinning machine, high requirements for uniformity of the spun yarn and the frequent use of the vacuum system for suction of a relatively great length of the faulty yarn, there is a high probability of the necessity of sucking off the faulty yarn simultaneously. Solving this problem by increasing the rated power input of the vacuum source is for such high numbers of of work stations of an open-end spinning machine is uneconomical.
This drawback is not solved by the background art, or it is addressed by uneconomical means. The aim of the invention is therefore to overcome this drawback without increasing the performance of the vacuum source.
The goal of the invention is achieved by a method for removing the faulty yarn portion at a work station of an open-end spinning machine after a work station is stopped in a controlled manner, whose principle consists in that before the request to connect a suction nozzle of a work station for sucking off the faulty yarn portion, the value of the vacuum in the central channel of the vacuum system of an open-end spinning machine is determined and evaluated and the suction nozzle of the work station is connected to the central vacuum channel only if the current capacity of the vacuum source detected is sufficient or only after achieving sufficient vacuum.
The advantage is the fact that there cannot be such a decrease in vacuum which would lead to insufficiently efficient suction of yarn.
The aim of the invention is also achieved by a device whose principle consists in that each suction nozzle for sucking the faulty yarn portion is connected to the central channel of the vacuum system of an open-end spinning machine by means of a valve, which for the purpose of control coupled to a control unit connected to a vacuum meter arranged in the central channel of the vacuum system of an open-end spinning machine.
An exemplary embodiment of a device according to the invention is shown in
A known work station of an open-end spinning machine comprises a spinning unit, from which the spun yarn is withdrawn by a drawing-off mechanism. A sensor I of the quality of yarn is situated in front of the drawing-off mechanism and a sensor of the presence of yarn is situated behind the drawing-off mechanism. The yarn is wound by a winding device onto a final bobbin. The work station comprises a suction nozzle 2 connected to the central channel 3 of the vacuum system of an open-end spinning machine by means of a stop valve 4.
The stop valves 4 are connected to the control unit 5, to which is also permanently connected the outlet of a vacuum meter 6 arranged in the central channel 3 of the vacuum system of an open-end spinning machine. A control unit 5 may be a control unit of a work station, or a control unit of a respective portion of an open-end spinning machine, or, optionally, it may be the central control unit of an open-end spinning machine.
The performance of the vacuum system of an open-end spinning machine is limited by a number of all the work stations simultaneously connected to the central channel 3 of the vacuum system of an open-end spinning machine.
The instantaneous value of vacuum needed for sucking off the defective yarn at one work station of the machine is known and is stored in the memory of the control unit 5 of the machine.
The minimum value of vacuum needed for unwinding the faulty yarn portion from the final bobbin and sucking it off out of the work station and thus the requirement for the capacity of the vacuum source is defined. An insufficient level of the vacuum would result in an incorrect operation of the device.
After detecting a defect of the spun yarn by a sensor 1 of quality and after passing the particular signal to the control unit 5, the control unit 5 stops the particular work station in a controlled manner. This activity includes unwinding the spun faulty yarn portion at the particular work station of the machine. The control unit 5 finds out the current value of the vacuum in the central channel 3 of the vacuum system of the machine sensed by the vacuum meter 6 and evaluates it as the remaining capacity of the unillustrated vacuum source.
If this remaining capacity is sufficient, the signal of the control unit 5 opens the stop valve 4 of the particular work station, whereupon suction of the faulty yarn portion by the suction nozzle 2 is started, as well as its removal to the unillustrated waste space.
If the remaining capacity is insufficient for reliable operation of another work station, the control unit 5 does not give a signal to open the stop valve 4 at another work station and waits until the process of unwinding and sucking off the faulty yarn portion at any of the currently simultaneously attended work stations is terminated. It is only after terminating the operation at any of the currently simultaneously attended work stations and after detecting new data and evaluating the current capacity of the vacuum source, the control unit 5 sends a signal to the waiting work station. Upon this signal the stop valve 4 opens, the suction nozzle 2 is connected to the central channel 3 of the vacuum system of an open-end spinning machine, by which means the operation of sucking off and unwinding the faulty yarn portion is started.
The advantage of the method and device according to the invention is performing properly the operation of sucking off the defective portion of the spun yarn and removing it out of the work station of an open-end spinning machine without having to use a high-performance vacuum source. The loss caused by the downtime of the work station waiting for the necessary vacuum in the suction channel is usually lower than are the acquisition and operating costs which would be required by a more powerful source of vacuum.
| Number | Date | Country | Kind |
|---|---|---|---|
| PV 2015-232 | Apr 2015 | CZ | national |
