WO2001051397A1

WO2001051397A1 - Method for detecting quality features on yarn

Info

Publication number: WO2001051397A1
Application number: PCT/CH2001/000023
Authority: WO
Inventors: Rolf Joss; Hans Wampfler
Original assignee: Zellweger Luwa Ag
Priority date: 2000-01-14
Filing date: 2001-01-12
Publication date: 2001-07-19

Abstract

The invention relates to a method and device for detecting quality features on yarn which is processed in parallel at a number of production points (1, 2, 3). The aim of the invention is to provide a method and device which enables the determination of outliers with a small or justifiable amount of effort and thus taking quality features into account which are essential for the subsequent processing of the yarn. To this end, the invention provides that, on the yarn and at each production point, a value for a parameter is detected again and again from the yarn surface and from a drifting movement of a sensor (8, 9), and a statement with regard to the production point is produced during detection. The detected value should be processed together with the statement in such a manner that an indication regarding the operational mode of the production point is obtained from this processing.

Description

METHOD FOR DETECTING QUALITY CHARACTERISTICS ON YARN

The invention relates to a method and a device for recording quality features on yarn that is processed in parallel on several production parts.

The average quality of the products that are produced today in a spinning process is already very high. This high quality is achieved through powerful controls for the spinning process and through high-quality preprocessing of the starting material for the spinning process. Seen over the length, the aim is to achieve the most uniform possible mass of the yarn by means of a complex regulation in the previous stretching process of the fiber wadding. By continuously monitoring the spun yarn at all production points, that is to say at all spinning and / or winding points, and by means of suitable control interventions, a very high quality can even be achieved. If the monitoring is carried out continuously in all or at least in several successive processing stages, this results in an expensive production system, the monitoring and control means of which are rarely required, namely with so-called outliers. Outliers can be one-off or rare defects in the yarn, or it can be individual production sites that work exceptionally badly and that deliver permanently bad yarn. Although such outliers do not occur very often, they are very harmful because they cause high costs, for example, because a significant amount of production can be devalued if the outliers are not recognized or are recognized only late. High-priced quality goods can suddenly be downgraded to low-priced goods without reducing the effort. Outliers are always noticeable in the subsequent processing of yarn into woven or knitted fabrics. Either as a defect in the end product or as a cause of difficulties in weaving, dyeing or finishing. In order to avoid this, it is common today to check the quality of the product, i.e. the yarn, frequently in the laboratory or continuously on the production machine. While it is possible in the laboratory to test a wide variety of parameters such as yarn diameter, hairiness, fineness, twist, etc., ongoing monitoring practically only allows the detection of a single quality parameter. This is usually the mass or the cross section. If you want to continuously measure more than one parameter, the costs for it rise sharply, or you are satisfied with cheap and simple sensors that only carry out a rudimentary measurement and thus also uncertainties in the evaluation and interpretation of the Create measurement results. Possible approaches to overcoming the dilemma described above can be found in the documents mentioned below.

From EP 0 924 324 and 0 927 887 it is known to detect the diameter of the yarn on a spinning station periodically by means of a sensor which is arranged in front of the spinning stations. In this way, a large amount of data about the diameter of the yarn can be obtained, which can also be continuously evaluated. This makes it easy to find poorly running spinning positions and those that generate periodic errors. The costs for this are limited.

A disadvantage of these known methods and devices is that outliers are only recognized if they relate to the diameter or the mass of the yarn. Other properties of the yarn that can deteriorate are not recognized in this way.

From EP 0650915 it is known to periodically monitor the structure and the winding quality of bobbins that are produced on a bobbin winder, as well as the diameter of the yarn. This gives data relating to the diameter or mass of the yarn and the structure of the bobbins.

A disadvantage of the known device can be seen in the fact that it only detects outliers which relate to the structure of the bobbins or the diameter or the mass of the yarn. The effort required for this is great.

DE 195 01 204 A1 discloses a method and a device for measuring hairiness on containers such as cotton wraps and bobbins. An optical measuring field is applied to the edge area of the container and the brightness values determined are evaluated mathematically.

This device or this method is particularly suitable for testing containers in our own test facilities either in the laboratory or as an intermediate stage that is activated in production. Here too, measurements in the laboratory can be done too rarely, while measurements at all production sites are very expensive.

It is therefore an object of the present invention to provide a method and a device which allows the detection of outliers with little or justifiable effort and takes into account quality features which are essential for the subsequent processing of the yarn. This task is solved in that for a quality feature, which is particularly meaningful with regard to outliers, measured values are repeatedly recorded in the production process at intervals, whereby the intervals between the measurements can range from several seconds to hours. A parameter that depends on the surface of the yarn is proposed as the preferred quality feature. For example, a value for a parameter that appears on the surface of the yarn should be recorded on the test material at each production site. Such a parameter can be the hairiness of the yarn, the foreign matter or foreign fiber content, the material or its composition, the mixing ratio of different materials, etc. When recording, an indication should also be given about the production site and the recorded value should be processed together with the information in such a way that an indication of how the production site works can be obtained. This note is intended to indicate whether the yarn produced has values within the set limits for the selected parameter. In addition, values of other quality characteristics can be recorded, which are helpful for the detection of outliers.

The device for recording quality features on a thread-like test material typically has several production sites arranged next to one another with wound test material, as is the case for yarn in spinning and winding machines with the bobbins. A movement path for sensors is provided, which runs next to the production points, on which at least one first sensor for detecting the parameter on the test item is movably arranged. Another sensor for detecting a position of the first sensor along the movement path is also provided. This also includes a drive and an evaluation unit for the first and the further sensor, so that the sensor moves past the production points on its path of movement, detects the parameters of the yarn at the production points and the position and forwards them to the evaluation unit. In addition to the first sensor, a second sensor can also be provided for measuring the shape, the diameter or other properties of a bobbin, such as projecting yarn sections, etc.

The advantages achieved by the invention can be seen in particular in the fact that certain parameters of the yarn are influenced by several properties and thus several properties which cause outliers are recorded with one parameter. For example, hairiness as a possible measured parameter is influenced by properties such as wear on the spinning materials such as yarn guides, rotors, belts, rollers, separators etc. or machine settings such as the suction pressure during compact spinning etc., so that there are large deviations in these properties in values for express the hairiness. Bad values for a property are often expressed in the Hairiness and hairiness is a good indicator of the good or bad work of a spinning or winding unit. In addition, hairiness has a great influence on the quality of an end product such as a woven or knitted fabric, namely on the structure and the further treatment such as dyeing, etc. It is known that yarn with a high hairiness absorbs color better than yarn with a low hairiness. If the hairiness of the yarn in a fabric is not uniform, streaks can be expected in the fabric. In the case of a yarn, high hairiness means, for example, that compaction has not been successful and that the yarn body is therefore small or has a comparatively small diameter. Viewed from the outside, however, the overall diameter is relatively large. Nevertheless, such a yarn has a lower tensile strength and therefore this means a danger for the subsequent processing. For example, it can no longer endure and tear the loads caused by a weaving machine. This also reduces the utilization of the weaving machine. The same can also apply to parameters such as the twist of the yarn, the material composition, etc. For example, the behavior of the yarn during the dyeing is influenced by the composition, so this parameter must be observed when the yarn is to be used for dyed fabrics.

Since, according to the invention, significantly fewer sensors have to be provided for a production machine than there are production sites, the costs for the sensors are greatly reduced or, for the same or lower costs, sensors can be used which work much more precisely or even measure values which are relevant to use every production site is not so easy to measure. Instead of measuring only one value or one quality characteristic, a further sensor for a further quality characteristic can be integrated into the same device without much additional effort. Such a second or additional quality feature can relate, for example, to the structure of the spools on which the yarn is or is wound. In this way, one gains further knowledge about how a winding unit works.

The device according to the invention can easily be adapted to increasing demands, the outlay correspondingly increasing only gradually. For example, one, two or as many sensors can be provided for a predetermined number of production sites as the period after which a measurement is to be taken, if this period is predetermined.

If the device according to the invention is arranged on a spinning machine, then a separate device for identifying defective bobbins or bobbins is also superfluous, since a sensor detects the position of a bobbin and thus, together with the value for the measured property, provides an evaluation unit with information about poorly running production sites , Coils and bobbins no longer need to be tracked to Determine outlier spindles. In this way, control over the quality of workmanship and the occurrence of outliers in a production facility can be increased starting at a low level, in any dosage.

The invention is explained in more detail below using an example and with reference to the accompanying figures. It shows

Figure 1 is a schematic view of the device according to the invention

FIG. 2 shows a schematic view of part of a further embodiment of the device according to the invention,

FIGS. 3, 4 and 5 each further partial views of the device,

FIGS. 6 and 8 each show a schematic representation of a device for recording a parameter,

Figures 7 and 9 each show a waveform and

Figure 10 is an illustration of an outlier.

In the following description, the term coils is generally used for the sake of simplicity. Depending on the application, e.g. cops for ring spinning machines, conical bobbins for winding machines, cylindrical bobbins for other spinning machines or spinning processes, etc.

1 shows a plurality of production sites arranged next to one another, here in particular spinning stations 1, 2, 3 of a spinning machine by its spools 4, 5, 6, on which yarn is wound. A movement path 7 for sensors, which is formed, for example, by a rail, is provided next to the production points 1, 2, 3. There is a first sensor 8 for detecting a parameter and optionally also a further sensor 9 for detecting the position along the movement path, both of which can be moved together. A sensor 9 can also be permanently assigned to each product location 1, 2, 3, etc. A drive 10 is provided for the sensors 8, 9, which moves them back and forth on the movement path 7. The movement path 7 can also be circumferential, so that it only has to be driven in one direction. The drive 10 can for example consist of a circumferentially arranged string 11, which by a Drive device 12 is driven and is guided by deflection rollers 13. Such drives 10 are known per se and are therefore not shown in detail here. A drive with a linear motor would also be conceivable. Via a data bus 14, the sensors 8, 9 are connected to an evaluation unit 15, which consists, for example, of a suitably programmed processor with means for inputting and outputting data. Such processors are well known and are therefore not shown in detail here. The spinning stations 1, 2, 3 can be assigned further fixed elements, such as a light source or a reflector 16, as shown here only for the spinning station 3. In the embodiment shown here, the sensor 8 is arranged in relation to the coil 6 such that grazing detection of the cylindrical peripheral surface 17 is possible. The movement path is therefore also arranged next to the conical part 18 of the coils 4, 5, 6.

Fig. 2 shows a device with conical coils 19, 20, 21, which are aligned on a common axis 22. Here, a movement path 24 is provided for a sensor 23, which runs at a distance 25 from the axis 22. This arrangement is advantageous in winding machines.

FIG. 3 shows a possibility of how a sensor 23, as is known from FIG. 2, and is moved on a movement path 24, which is perpendicular or parallel to the plane of the drawing, can work together with a further element 25, which is beyond the coil 26 is arranged. The further element 25 can represent a light source, a reflector or something comparable.

FIG. 4 shows a sensor 28 which is designed to detect a field 29 on the surface 30 of a coil and, by means of image processing, values about the hairiness and possibly other quality features such as the rotation, the diameter, foreign fibers etc. from an image of the field 29 to capture.

FIG. 5 shows the device from FIG. 1 from a viewing angle pivoted through 90 °, so that, for example, the coil 6 and the position of the sensor 8 and the element 16 can be better recognized.

FIG. 6 shows a basic diagram of a sensor 31 with which a parameter such as the hairiness of yarn on a spool 32 can be detected. This also includes a fixedly arranged and sufficiently extended light source 33, which is arranged behind the coils. The sensor 31 consists of a lens or an objective 34, an aperture 35 and one Detector 36. Two beam paths 37 and 38 can also be seen, which image pixels 39 on the diaphragm 35 and image points 40 on the detector 36. In principle, direct light from the light source 33 is thrown onto the diaphragm 35 and scattered light from the hair is thrown onto the detector 36, and several such detectors can also be arranged at other locations next to or behind the diaphragm 35.

FIG. 7 shows a signal curve 41 which is recorded via axes 42 and 43 and represents values as received by the detector 36 according to FIG. 6. Signal deflections 44 and 45 indicate the edges of a coil. Values for the position of the sensor and values for the received intensity of the light are plotted along the axis 42 and 43 along the axis. The light received becomes brighter upwards.

8 shows a further sensor 46 for measuring properties of the yarn on a spool 47. The sensor 46 consists of a lens or an objective 48, a semi-transparent mirror 49, a transmitter 50 and a receiver 51. With 52 the path is one Denoted pixel 53, which is still sharply imaged in the area of boundaries 54, 55.

FIG. 9 shows a signal curve 56 which is recorded via axes 57 and 58 and represents values as received by sensor 50 according to FIG. 8. Values for the position of the sensor are plotted along axis 58 and values for the received intensity of light are plotted along axis 57. The light received becomes brighter upwards.

10 shows a representation of measured values plotted over axes 59 and 60. Areas for production sites, designated 101-109, are delimited along the axis 59. Values for a property, as can be detected by the aforementioned sensors, are plotted along the axis 60. Broken lines 61 and 62 delimit a range in which normal values should lie. 63 denotes a value that lies far outside the range mentioned and is therefore considered an outlier.

The mode of operation of the invention is as follows:

On a spinning machine on which dozens or hundreds of spinning stations 1, 2, 3 are arranged side by side, one or more sensors 8, 9 each pass in front of or behind the bobbins on which the yarn is continuously wound, past the spinning stations, and if a specific and suitable point on the movement path 7 pass a measured value for a parameter and a measured value for the position along the movement path 7 or, which is equivalent, record information about the spinning station 1, 2, 3 on which the parameter is currently being measured. The sensors 8, 9 are moved continuously or discontinuously on the movement path 7, so that they repeatedly record the measured values and data at each spinning station 1, 2, 3 and transmit them to the evaluation unit 15 via the bus 14. Threshold values, for example, are pre-stored in the evaluation unit 15, with which the incoming values for the parameters are compared. Such threshold values limit an upper and lower tolerance range, for example, which should not be exceeded if possible. If you want to determine so-called outliers, the tolerance range is rather wide, so that the most common values for the parameter lie in this tolerance range. Outliers are then those values that are normally rarely measured and which exceed the tolerance limits upwards and downwards, as can be seen from FIG. 10. Such outliers are related to the information about the location or the spinning position, so that the evaluation unit 15 can indicate the outlier and the production point 1, 2, 3 by means known per se for display, such as a screen or printer. The evaluation unit 15 can also be connected to a machine control, or even form part of it, and can be designed such that, starting from the report about one or more outliers, a measure such as the interruption of production, for example by generating an artificial thread break or the Assignment of the coil to a specific quality group of the coils is initiated.

A second sensor 27 (FIG. 1) can be used to provide further information about the production site or the production at this point. For example, the sensor 27 can be designed to check the build-up of a layer of the yarn on the bobbin or the contours of the bobbin and, for example, to indicate whether all of the yarn sections in the layer that has just been set up run correctly, for example in parallel, or whether individual yarn sections of the layer or protrude from the contours of the coil. Further sensors can also be arranged on the same movement path. For example, a sensor that measures the uniformity of the diameter or the mass of the test material as a quality feature and whose values are also compared in the evaluation unit with its own tolerance limits. However, all sensors are preferably driven by the same drive 10. The evaluation unit 15 can also be programmed so that an outlier is only reported when the tolerance limits for several quality features are exceeded. If the hairiness on the coil is to be recorded as a parameter, the arrangements shown in FIGS. 6 and 8 can be used. However, sensors of the type known from PCT / CH97 / 00300 or CH 668483 can also be used. Sensors for detecting the mass or the diameter of yarn are known from EP 761 585. Such for the construction of the layers or the contours from EP 0 650 915. A method or a device according to EP 0271 728 can be used to record a parameter such as the twist of the yarn. Foreign substances and foreign fibers can be recorded according to CH 1994/98.

A sensor can, however, also be arranged as shown in FIG. 4 and, of course, also be provided on a path of movement not shown here. Such a sensor 28 processing an image of the field 29 of the surface can detect several quality features in one image. For example, the hairiness, the rotation, the diameter, protruding yarn sections, etc. Such a sensor with the evaluation unit connected to it can accordingly be expensive and possibly take a relatively long time to obtain the data from the image. As a compensation, however, his wandering movement should be adjusted accordingly slowly, so that he needs enough time to move from one coil to another and can end his evaluation of the values just recorded during this time.

The hairiness of the yarn on the bobbin 32 can be detected with the sensor 31 according to FIG. 6. For this purpose, the coil 32 is illuminated from behind from the point of view of the sensor 31 by a light source 33, which can be designed as a luminous band or as a reflector. When the sensor 31 moves past the coil in a known manner, the image 64 of the image point 39 slides past on a path 65. The image 64 hits the diaphragm 35, which blocks the light from the beam path 37. If hair is placed in front of the image point 39, for example, it is deflected by the scatter on the hair so that it appears as the image point 40, resulting in a beam path 38 which runs next to the aperture 35 and onto the detector, for example, located next to the aperture 36 falls. This converts the received light into an electrical signal 41, which is shown for example in FIG. 7. The two signal swings 44 and 45 correspond to the flanks of the coil 32. That is, the largest swings occur when the beam path 37 brushes the surface of the coil 32. Depending on how steep the increase in signal deflection 44 or the decrease in signal deflection 45 is, the hairiness also results. A steep rise or fall corresponds to less, a flat rise or fall corresponds to a great hairiness. With the sensor 46 according to FIG. 8, the transmitter 50 generates an image point 53 on the path 52, which on this travels to the coil 47. The image point 53 is always also reflected on the receiver 51 at the semi-transparent mirror 49, but this means that normally very little light is returned to the receiver 51. However, if the pixel 53 hits the coil 47, the intensity of the signal which the receiver 51 receives increases sharply. This can be seen from the signal course 56 from FIG. 9. If the yarn on the bobbin is provided with hairiness, there is a smooth transition between the signal sections, ie the flanks 66, 67 are less steep and thus give a measure of the hairiness ,

Claims

claims:

1. A method for recording quality features on yarn that is processed in parallel on several production sites (1, 2, 3), characterized in that values for a parameter are acquired by a sensor (8) at at least two production sites that result from the yarn surface be obtained that when the parameter is recorded, an indication of the production site is also generated and that the recorded value is processed together with the specification in such a way that an indication of the functioning of the production site is obtained therefrom.

2. The method according to claim 1, characterized in that, in addition to the value for the parameter, values of at least one further quality parameter are detected which are helpful for the detection of outliers.

3. The method according to claim 2, characterized in that the position of the test material on a coil is recorded as a further quality feature.

4. The method according to claim 1, characterized in that as values for a parameter those from a group of parameters are recorded which contain the hairiness of the yarn, the foreign substance or foreign fiber content, the material or its composition.

5. Device for recording quality features on yarn, characterized by a plurality of production sites (1, 2, 3) arranged next to one another with wound yarn, a movement path (7) for sensors (8, 9) which runs next to the production sites, at least one first sensor (8) on the path of movement for detecting a parameter on the surface of the yarn, another sensor (9) for detecting a position of the first sensor along the

Movement path, a drive (12) for the first sensor and an evaluation unit (15) for the first and the further sensor, so that the sensor is moved past the production points on its movement path

Parameters at the production sites and the location are recorded and forwarded to the evaluation unit.

6. The device according to claim 5, characterized in that a second sensor is provided for detecting values about the structure of the coils.