EP3760772A1 - Optimization of the operation of a spinning machine - Google Patents

Abstract

The present invention relates to a method for optimizing the operation of a spinning machine in terms of quality and productivity. The invention also relates to a device comprising a control device and the spinning machine. According to the invention, a yarn is produced with predetermined yarn properties, a quality parameter of the yarn is recorded during the spinning operation, a parameter for setting the production speed is specified, the quality parameter and the parameter for setting the production speed are evaluated and the production speed is set as a function of a target variable, the target variable including the quality parameter.

Description

The present invention relates to a method for optimizing the operation of a spinning machine, in particular an open-end rotor spinning machine or an air jet spinning machine, with regard to quality and productivity. The invention also relates to a device comprising a control device and the spinning machine.

The EP 2 565 306 B1 discloses an open-end rotor spinning machine in which the speed of the spinning rotors is automatically set as a function of a respective determined thread breakage rate and thereby the thread breakage rate is regulated so that the thread breakage rate is within a predetermined target range below a maximum thread breakage rate. The speed of the spinning rotor directly determines the production speed of the open-end rotor spinning machine. So that given yarn parameters or yarn properties are maintained when the speed of the spinning rotors changes, the thread take-off speed and the feed speed of the sliver are changed in accordance with the speed of the spinning rotor.

During rotor spinning, the yarn is formed in the rotor groove of the spinning rotor. Here, the deposited fibers are given a twist as a result of the torsional moment of the rotating yarn end. This rotation creates the yarn strength necessary for the yarn to be drawn off. When the yarn is withdrawn from the rotor groove, the yarn must have a strength that is greater than the centrifugal force generated in the rotor by the rotation of the yarn. Otherwise the thread would break in the area of the rotor. With an almost constant tear force, the centrifugal force of the rotating end of the yarn increases quadratically with an increasing rotor speed. A doubling of the rotor speed leads to four times the thread tension in the area of the rotor. The risk of thread breakage in the area of the rotor thus increases as the rotor speed increases.

The thread breakage rate that can be accepted when operating an open-end rotor spinning machine depends on the number of means available to repair the thread breakage. The thread break rate is the number of thread breaks in relation to the operating time of the open-end rotor spinning machine or a job. The thread breakage is remedied by a piecer. The piecing can be carried out semi-automatically, which means that an operator is required for the piecing. The piecing can also take place automatically by means of a piecing carriage. Machines are also known in which piecing can be carried out automatically at a work station. In the first In this case, the number of acceptable thread breaks depends on the number of operators available. In the second case, the permissible thread break rate is determined by the number of piecing cars. In the case of self-sufficient piecing at the work place, it is important how many piecings can be carried out in parallel without impairing a sufficient negative pressure supply. On the basis of the conditions described, a maximum permissible number of thread breaks can be specified.

The speed with which the yarn is produced and thus the productivity of the open-end rotor spinning machine increase with increasing rotor speed. It is therefore desirable that the spinning rotors are operated at the maximum possible speed.

The DE 10 2004 053 505 A1 discloses a method for optimizing the productivity of an air jet spinning machine by reducing the production speed with an increased number of thread breaks and increasing it with a reduced number of thread breaks. Here too, the production speed is set as a function of the yarn breakage rate. To change the production speed, the delivery speed and the withdrawal speed are adjusted accordingly. So that the spin rotation remains constant in relation to the delivery speed, the compressed air is adjusted accordingly depending on the production speed.

The aforementioned documents only consider the productivity of the spinning machines. However, the quality of the yarn produced is also of crucial importance. Therefore, so-called yarn clearers are known in the prior art, such as, for example EP 0 877 108 B1 described.

Yarn clearers record measurable properties of the yarn during the production of the yarn. In this way, yarn defects should be determined. A cleaning limit can be used to determine which yarn defects are cleaned out and which remain in the yarn. In addition to clearing out yarn defects, the yarn clearer also enables the quality of the yarn to be assessed.

It is the object of the present invention to optimize both productivity and quality in yarn production.

The object is achieved by a method for optimizing the operation of a spinning machine in terms of quality and productivity. According to the method according to the invention, a yarn with predetermined yarn properties is produced, a quality parameter of the yarn is recorded during the spinning operation, a parameter for setting the production speed is specified, the quality parameter and the parameter for setting the production speed are evaluated and the production speed is set as a function of a target variable, the target variable comprising the quality parameter.

The optimization is preferably carried out for an open-end rotor spinning machine or for an air jet spinning machine.

The yarn properties are e.g. B. Yarn count and twist. In addition, the raw material used influences the yarn properties. The yarn properties can preferably also be specified by machine and / or production parameters. This includes in particular the spinning means, such as spinning rotors, opening rollers and take-off nozzles or spinnerets. In addition, the spinning vacuum or spinning pressure, the draft given by the spinning device and the given rotation play a role. With the open-end rotor spinning machine, the relationship between the take-off speed, sliver feed and rotor speed is important. In the case of an air jet spinning machine, it is the relationship between the spinning pressure and the delivery speed.

Quality parameters preferably describe deviations from specified yarn properties. In order to optimize the production of the yarn, the CV value and / or IPI values are particularly preferably used. The CV value is a measure of the evenness of the yarn; the more uneven the yarn, the higher the CV value. The IPI values are so-called frequent yarn defects (imperfections) which, viewed individually, are not assessed as disturbing. For the most part, they are below the clearing area activated in the short error matrix. IPI values for thick places, thin places and neps can be specified.

As already described above, the rotor speed in particular comes into consideration as a parameter for setting the production speed in an open-end rotor spinning machine. In order to maintain the yarn properties, the infeed and take-off speed must then be adjusted accordingly. The air jet spinning machine can be used as a parameter for setting the production speed the delivery speed can be selected. The spinning pressure is adapted to the delivery speed to maintain the yarn properties.

The invention is based on the knowledge that the production speed of the spinning machine has a direct influence on the quality of the yarn produced. As the production speed increases, the quality of the yarn produced decreases. By setting the production speed as a function of a quality parameter, maximum productivity can be achieved while maintaining a desired quality. To further increase productivity, the limits for the quality parameter can be adjusted.

The optimization can be carried out for the entire spinning machine, i.e. all workstations are operated at the same production speed. The setting is then preferably made on the basis of mean values or on the basis of the evaluation of the production speed and quality parameters at a pilot spinning station. It is also possible to optimize each job individually. This requires self-sufficient workplaces that are equipped with individual individual drives. Each job can produce at its own individual production speed. This means that different limits for the quality parameters and different yarn properties can be specified for each job. Groups of workplaces on which yarns with the same yarn properties are produced can also be combined for optimization.

The production speed is preferably set with the aid of a control device as a function of a target variable, the target variable including the quality parameter. The control device can preferably be equipped with artificial intelligence.

Accordingly, the object is also achieved by a device which has a control device and a spinning machine. The device comprises means for producing a yarn with predetermined yarn properties, means for detecting a quality parameter of the yarn during the spinning operation and means for specifying a parameter for setting the production speed. According to the invention, the control device is designed for evaluating the quality parameter and the parameter for setting the production speed and the control device is designed so that the setting of the production speed with the aid of Control device can take place as a function of a target variable, the target variable including the quality parameter.

The control device can be part of the spinning machine and in this case is preferably designed as a central control device and / or workstation control. In addition to the tasks involved in the optimization according to the invention, the integrated control device also preferably takes on the known control functions of a spinning machine. The control device can also be (spatially) independent of the spinning machine. It is only necessary that the required data can be exchanged between the control device and the spinning machine. For this purpose z. B. within a spinning mill, the control device can be connected to the spinning machine via a network. The control device can then also be connected to further spinning machines in the spinning mill for optimization. In certain embodiments described below, a connection of the control device and the spinning machine to the Internet can be advantageous. The control device can preferably be designed as a PC, laptop or tablet or comprise these.

The means for producing a yarn are preferably designed as a spinning device, in particular as an open-end rotor spinning device or an air jet spinning device. The means for detecting a quality parameter of the yarn are preferably designed as yarn clearers. An operating device can be present to specify a parameter for setting the production speed.

According to an advantageous development of the method according to the invention, the thread breakage rate is recorded and evaluated and the target variable includes the thread breakage rate. In this embodiment, the target variable therefore includes both the quality parameter and the yarn break rate. This means that the production speed is set both as a function of the quality parameter and as a function of the thread breakage rate. The production speed is preferably set in such a way that both the quality parameters and the thread breakage rate are within specified limits. In this way, both productivity and quality can be optimally adjusted. It can thus be ensured that the production speed is only so high that the thread breaks that occur can still be eliminated. The production speed is also limited in such a way that the quality parameter remains within the specified limits.

Accordingly, an advantageous embodiment of the device according to the invention has means for detecting the thread breakage rate, the control device is designed to evaluate the thread breakage rate and the target variable includes the thread breakage rate. Thread breaks can be determined in a manner known per se with the help of thread monitors or with the help of yarn clearers. A corresponding evaluation device evaluates the thread breaks and determines the thread break rate. The evaluation device can also be part of the control device.

According to a preferred embodiment, the control device comprises a user interface on which the parameters for setting the production speed and the target variable are displayed at the same time. This means that in addition to the parameter for setting the production speed, at least the quality parameter is displayed on the user interface. Depending on the design of the target variable, further quality parameters and / or the thread breakage rate are displayed on the user interface. The parameters for setting the production speed can preferably also be changed via the same user interface. The operator receives all the relevant information he needs to set the production speed. With the help of the user interface, the setting is simplified for the operator. The user interface can be part of an operating device of the spinning machine or the screen of a PC, laptop or tablet.

A representation of the time course of the parameter for setting the production speed and the target size on the user interface is particularly clear. This enables the operator to easily see how changes in the production speed affect the target size and decide whether the production speed can be increased or should be decreased.

A limit value for the target variable can preferably be specified for the control device. Preferably, an upper and a lower limit value for the quality parameter are specified or can be specified by means of the control device. When it comes to the yarn break rate, the upper limit value is the most important. The limit value or values are preferably also displayed on the user interface. A representation of the limit value or values in the representation of the course over time is also advantageous.

According to a possible embodiment of the device according to the invention, the control device is designed to measure the production speed or the parameter To automatically change the setting of the production speed depending on the deviation of the target variable from the predetermined limit value

The control device can preferably be designed to determine suggestions for a change in the parameter for setting the production speed. The suggestions are determined as a function of the deviation of the target variable from the specified limit value. The respective suggestion is preferably displayed to the operator on the user interface. In connection with a corresponding design of the control device, the operator can then confirm the suggestion or change it manually and only then confirm it. The change in the production speed is only carried out by the control device with the confirmation.

Artificial intelligence principles can be used to optimally set the production speed of the spinning machine. In connection with the present invention, the method of case-based reasoning is particularly advantageous. Problems are solved by reasoning by analogy. In order to create the case basis required for this, the control device is designed to create and store data records which include the predetermined yarn properties, the parameters for setting the production speed and the associated target variable. As already explained, the controller preferably has a connection to the Internet. This means that not only local data sets, but also data sets from other spinning mills are available. This can significantly increase the case base and accelerate the learning of the system.

In order to determine a suitable case among the stored data sets, the control device is preferably designed to compare the data sets with the specified yarn properties and a specified limit value for the target variable and to select a data set for operating the spinning machine as a function of the comparison. The device is preferably designed to use the selected data set. That is to say, a data record is preferably selected by comparison and the spinning machine is preferably operated on the basis of the selected data.

So that the operator can evaluate and revise the selected data record, the control device has an interface for revising the selected data record.

The control device is preferably designed to use and store the revised data set. In this way, the data set can be checked and then the case base can be expanded.

Fig. 1

eine Benutzeroberfläche zur Durchführung der erfindungsgemäßen Optimierung;

Fig. 2

eine Darstellung des zeitlichen Verlaufs des Parameters zur Einstellung der Produktionsgeschwindigkeit und der Zielgröße;

Fig. 3

eine schematische Darstellung der Optimierung nach dem Prinzip des fallbasierten Schließens

The invention is explained in more detail below using an exemplary embodiment. Show it:

Fig. 1

a user interface for performing the optimization according to the invention;

Fig. 2

a representation of the time course of the parameter for setting the production speed and the target size;

Fig. 3

a schematic representation of the optimization according to the principle of case-based reasoning

The Fig. 1 shows a user interface of a control device with the aid of which the operator of the spinning machine can set the production speed as a function of a target variable. In the exemplary embodiment, the target variable comprises a quality parameter, namely a CV value, and the yarn break rate (yarn breaks). The CV value is given in%. The embodiment relates to an open-end rotor spinning machine.

The user interface initially contains information that allows conclusions to be drawn about the yarn properties. The lot name is displayed in field 1, the lot number in field 2, the yarn number in field 3 and the work area in field 4. The work area indicates the spinning positions for which the optimization is carried out. By specifying the lot number and the lot name, further machine and production parameters relevant to the yarn properties can be traced at any time.

The observation time that is to be used for optimization can be specified in field 5. The remaining time is given in field 6. A reference speed for the spinning rotor can be specified in field 9. Furthermore, a step size (Delta Rotor Speed) can be specified in field 7, with which the rotor speed is changed for optimization. The upper limit (max) for the thread break rate is specified in field 14. Field 16 enables the entry of a lower limit (min) for the CV value. The upper limit (max) of the CV value is specified in field 17.

The optimization process is started by actuating the start area 10. The process can be interrupted or ended with the stop surface 11. The operation of the spinning machine initially starts with the reference speed 9. The current rotor speed is displayed in field 8. The current production (Production) is displayed in field 12. This means that the meters of yarn produced are given. The current thread breakage rate 13 and the CV value 15 are also given. The specified limit values are indicated directly adjacent. The operator can now see at a glance whether and how far the yarn breakage rate 13 and the CV value 15 are from the limits. The operator can now change the rotor speed directly via the reference speed 9 or by pressing a button by the previously defined step size 7.

In an alternative embodiment, the control device is designed to make suggestions for changing the rotor speed. Such suggestions can e.g. B. can be displayed in a pop-up window. An algorithm can be stored in the control device which calculates this proposal on the basis of the deviation of the yarn breakage rate 13 and the CV value 15 from the predetermined limit values 14, 16, 17 and the step size 7. The operator has the opportunity to check the suggestion again before changing the rotor speed.

In order to make it easier for the operator to make a decision about a change in the production speed, the time course of the parameter for setting the production speed and the target variable can advantageously be displayed graphically. The Fig. 2 shows such a graphic representation again using the example of an open-end rotor spinning machine. A CV value is shown as the target variable.

The Fig. 2 shows the course 20 of the CV value and the course 21 of the rotor speed over time (time). In addition, the lower limit 18 and the upper limit 19 for the CV value are shown. At the beginning of the observation, the CV value lies within the assigned limits, but only slightly above the lower limit 18. Here, there is therefore the possibility of increasing the rotor speed and increasing productivity. The rotor speed is increased in several steps. The CV value increases until the upper limit value 19 is exceeded. The rotor speed is reduced again by the last step carried out. This means that an optimized operating point has been found that has a higher production speed. However, the CV value is still within the specified limits.

The Fig. 3 illustrates an optimization of the operation of a spinning machine in terms of quality and productivity using the principle of case-based closing. The process is largely automatic and is carried out by the control device according to the invention, which z. B. comprises an artificial intelligence chip.

The starting point for the optimization is a case base or a database 22. This database 22 contains a large number of data records 23 with optimized operating points of one or more spinning machines under predetermined conditions. For this purpose, the data sets contain the specified yarn properties, the parameters for setting the production speed and the target variable resulting therefrom. Reference number 24 defines predetermined conditions under which the operation of a spinning machine is to be optimized. The specified conditions 24 include at least the specified yarn properties and a specified limit value for the target variable. The conditions 24 are now compared with the data records 23 and the data record 22 which comes closest to the conditions 24 is selected (retrieve). This results in data record 25. By using this data record 25 under the specified conditions, the applied data record 26 (reuse) is obtained. Up to this point, the method described is preferably carried out automatically by the control device. The control device preferably has an interface that enables revision by the operator (revision). This gives the data record 27, which is finally transferred to the database 22 as data record 28 (retain). The control device thus learns and can access a larger database 22 for future optimizations.

Claims (12)

Process for optimizing the operation of a spinning machine in terms of quality and productivity,
whereby a yarn with specified yarn properties is produced,
a quality parameter (15) of the yarn being recorded during the spinning operation,
whereby a parameter (9) is specified for setting the production speed,
wherein the quality parameter (15) and the parameter (9) for setting the production speed are evaluated,
the production speed being set as a function of a target variable, the target variable comprising the quality parameter (15). Method according to Claim 1, characterized in that the thread breakage rate (13) is recorded and evaluated and the target variable comprises the thread breakage rate (13). Apparatus comprising a control device and a spinning machine
with means for the production of a yarn with predetermined yarn properties,
with means for detecting a quality parameter (15) of the yarn during the spinning operation and
with means for specifying a parameter (9) for setting the production speed,
wherein the control device is designed to evaluate the quality parameter (15) and the parameter (9) for setting the production speed,
the control device being designed so that the production speed can be set with the aid of the control device as a function of a target variable, the target variable including the quality parameter (15). Device according to Claim 3, characterized in that means are provided for detecting the thread breakage rate, the control device is designed to evaluate the thread breakage rate (13) and the target variable comprises the thread breakage rate (13). Device according to one of claims 3 or 4, characterized in that the control device comprises a user interface on which the Parameters (9) for setting the production speed and the target size are shown. Apparatus according to one of Claims 3 to 5, characterized in that the control device is designed to display the time profile (20, 21) of the parameter (9) for setting the production speed and the target variable. Device according to one of Claims 3 to 6, characterized in that a limit value (14, 16, 17) for the target variable can be predetermined for the control device. Device according to one of Claims 3 to 7, characterized in that the control device is designed to determine proposals for changing the parameter (9) for setting the production speed. Device according to one of Claims 3 to 8, characterized in that the control device is designed to create and store data records (23) which include the predetermined yarn properties, the parameter (9) for setting the production speed and the associated target variable. Apparatus according to Claim 9, characterized in that the control device is designed to compare the data sets (23) with the predetermined yarn properties and a predetermined limit value for the target variable and to select a data set (25) for operating the spinning machine as a function of the comparison. Device according to Claim 10, characterized in that the control device has an interface for revising the selected data record (26). Device according to Claim 11, characterized in that the control device is designed to use and store the revised data record (27).

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