Method for detecting structural defects in a bundled spun yarn comprising a core of parallel fibers bound together by wrapper fibers and coarse fibers, an apparatus for carrying out the method, a computer program for the apparatus, and a computer-readable medium containing the computer program

Abstract

The present invention relates to a method for detecting structural defects in a spun yarn having a core formed by parallel fibers, the core being bound together by a wrapping layer of fibers comprising wrapper fibers and coarse fibers, the method comprising: capturing moving yarn images along at least a portion of the yarn length by at least one optical yarn sensor, the optical yarn sensor comprising at least one row of radiation-sensitive elements and at least one radiation source, the optical sensor connected to electronic software processing the captured yarn images by digital image analysis to obtain data related to the yarn surface structure; evaluating from the obtained data changes in the yarn surface structure along the yarn length; comparing these changes in the yarn surface structure with predetermined criteria; and determining the occurrence of a structural defect in the yarn if these changes exceed the predetermined criteria. The present invention also relates to an apparatus, a computer program, and a computer-readable medium for carrying out the method.

Description

[Technical Field]

[0001] The present invention relates to a method for detecting structural defects in a bundled spun yarn that comprises a core of parallel fibers bound together by wrapper fibers and coarse fibers.

[0002] The present invention also relates to a device for detecting structural defects in a shied yarn.

[0003] Furthermore, the present invention relates to a computer program (product) comprising instructions for causing a device for detecting structural defects in a spun spun yarn to detect defects in a spun spun yarn during its manufacture, processing or analysis.

[0004] The present invention also relates to a computer-readable medium on which this computer program is stored. [Background technology]

[0005] Yarns are produced on textile machines equipped with suitable devices for converting a suitably constructed fiber sliver into yarn form. Various methods and associated yarn production devices are known. Yarns are produced, for example, on ring spinning machines, rotor spinning machines, and especially on air-jet spinning machines, which have recently made considerable progress.

[0006] Many different types of yarns are known, and the properties and structure of each yarn are determined and influenced by the yarn manufacturing technique and the settings of the respective manufacturing machine.

[0007] One type of yarn produced is a bundle-spun yarn, which includes a core consisting of a bundle of generally parallel fibers bound together by a wrapping layer of fiber. The wrapping layer compresses the parallel fibers that make up the yarn core, thereby increasing the frictional forces between the individual yarn fibers that are in direct contact. This compression has a positive effect on the overall yarn strength. The wrapping layer of fiber includes wrapper fibers and coarse fibers. The wrapper fibers are helically wrapped around the yarn core in a relatively stable manner with a relatively precise pitch. Coarse While it is true that the fibers are also helically wound around the yarn core, these helices have a variable pitch or perhaps even a variable direction, or some of the coarse fibers are incompletely wrapped around the yarn core. This incomplete wrapping of the coarse fibers around the bundle-spun yarn core manifests itself in two basic ways throughout the yarn structure. The first manifestation of the incomplete wrapping of the coarse fibers around the bundle-spun yarn core is a slack of such coarse fibers between two of their ends wrapped around the bundle-spun yarn core, i.e., the central portion of such coarse fibers forms a loop or tuft on the surface of the bundle-spun yarn. The second manifestation of the incomplete wrapping of the coarse fibers around the bundle-spun yarn core is an incomplete wrapping of the ends of the coarse fibers around the yarn core, where the unwrapped ends of these coarse fibers protrude from the yarn core and thus from the yarn itself. In the overall structure of the bundle-spun yarn, the ends of the wrapper fibers, and possibly also the ends of the core fibers, i.e., the ends of the parallel fibers that make up the yarn core, protrude from the bundle-spun yarn core. A typical manufacturing technique for forming bundled spun yarns is the production of yarns on an air-jet spinning machine, which is highly efficient and economically beneficial. Bundled spun yarns formed on jet spinning machines, also known as "air-jet yarns," are characterized by the unique structure described above, which includes a core made of parallel fibers wrapped with wrapper fibers and coarse fibers, i.e., the core is wrapped with a wrapping layer of fibers.

[0008] Nowadays, one of the indicators for evaluating the quality of yarns produced by various techniques, i.e., not only the above-mentioned bonded spun yarns, is the indicator of yarn hairiness. Yarn hairiness is characterized by multiple fiber ends or fiber loops that protrude or are free to move from the yarn or flat textile (fabric, jersey fabric, warp knit fabric, fleece). Therefore, the evaluation criterion for yarn hairiness is essentially the number of fibers protruding in a direction perpendicular to the yarn or the measured distance of the fiber ends from the yarn.

[0009] The technology for producing bundled spun yarns, for example, by air-jet spinning, also introduces problems and technical challenges unknown with previously used yarn production technologies (i.e., ring spinning and rotor spinning). One of these relatively recent problems associated with bundled spun yarns is the accidental occurrence of locations or lengths of the bundled spun yarn that exhibit specific structural defects in the bundled spun yarn; these specific structural defects in the bundled spun yarn are not noticeable in the bundled spun yarn at first glance, but they are objectively revealed, for example, by insufficient strength of the bundled spun yarn at that specific location or section and / or by poor appearance of the bundled spun yarn at that specific location or section; the manifestation of such structural defects is primarily detected only during subsequent processing of the already produced bundled spun yarn, for example, during finishing of the bundled spun yarn or during the production (weaving, knitting) of textile products from the bundled spun yarn. In some cases, these structural defects in the spun yarn only appear in the finished product before or after dyeing, e.g., in the finished fabric or knitwear, these defects, previously invisible to the human eye, become visible in certain locations in the fabric or knitwear, etc. These defects will hereinafter be referred to as "structural defects" because their origin lies in structural changes in certain parts of the spun yarn.

[0010] These structural defects in the yarn cannot currently be detected by conventional online bonded spun yarn quality control methods, for example, in the production of yarns on air-jet spinning machines, and further cannot be detected at all using non-contact methods of monitoring the quality of the bonded spun yarn during its production. Typically, users of air-jet spinning technology, i.e., bonded spun yarn manufacturers, attempt to prevent the occurrence of these structural defects in an empirical manner by setting the parameters of the bonded spun yarn production process, and it is usually not possible to check whether the settings are successful already during yarn production. Although this can be checked with feedback after the yarn has been produced, for example, by detailed yarn testing in a laboratory or by receiving responses from subsequent yarn processing equipment, this is highly undesirable due to the high cost of laboratory testing of large quantities of bonded spun yarn or the high risk of potentially producing large quantities of bonded spun yarn of insufficient quality that are delivered to customers.

[0011] The process of yarn formation and the influence of its specific structure on air-jet spinning machines are described in detail, for example, in the doctoral thesis "Spinning Machines for Air Jet Spinning," available at https: / / dspace.tul.cz / handle / 15240 / 26033. This paper aims to describe the process of yarn formation, investigate the influence of selected technological parameters of air-jet spinning machines on yarn properties, particularly air-jet yarn strength, and, above all, shed light on the air-jet yarn strength prediction problem. This paper addresses the analysis of air-jet yarn structures, providing calculations of the strength of the yarn core as a bundle of parallel fibers, as well as the strength of the fiber wrapping layer as a bundle of fibers helically wound around the yarn core. This paper also considers the interaction effects between the fibers in the yarn wrapping and the fibers in the yarn core. In addition to fiber parameters, yarn structure parameters are also used as input parameters for a model to calculate theoretical yarn strength at short gauge lengths. As an alternative approach to predicting yarn strength (in short sections), a statistical model is presented. Using this model, the effect of tensile tester gauge length on the strength and its coefficient of variation of ring-, rotor-, and air-jet-spun yarns was investigated.

[0012] One structural defect in a knot-spun yarn, for example, a yarn produced by an air-jet spinning machine, is the occurrence of defects in locations or sections of the yarn that reduce the strength of the knot-spun yarn but at the same time do not significantly affect the mass and / or diameter characteristics of the knot-spun yarn or the yarn hairiness parameters of the knot-spun yarn at those locations or sections. Nevertheless, monitoring the mass and / or diameter characteristics of the knot-spun yarn and monitoring the yarn hairiness are used to evaluate the quality of the knot-spun yarn during its production, for example, on an air-jet spinning machine. The hairiness of the knot-spun yarn is essentially evaluated as a statistical value obtained by measuring long sections of the yarn, i.e., sections of yarn tens to hundreds of meters in length, whereby the hairiness of the knot-spun yarn is later recalculated to a length of 1 cm or 1 m of the knot-spun yarn, which is not suitable for evaluating yarn defects that occur only locally or only in short sections of the knot-spun yarn.

[0013] To detect locations or sections of a knotted spun yarn where the yarn strength is reduced without significantly affecting the mass and / or diameter characteristics of the knotted yarn or the hairiness parameters of the knotted yarn at these locations or sections on an air-jet spinning machine, the solution disclosed in Patent Document 1 can be used. This document describes a sensor for detecting changes in the tension of a yarn moving through an air-jet spinning machine, which includes a contact element in the form of a pulley through which the measured yarn passes. The pulley is mounted on the arm of a deformation measuring element. Changes in the yarn tension caused by the local occurrence of structural yarn defects result in changes in the deformation of the deformation measuring element. These changes in the deformation of the deformation measuring element are detected and evaluated, for example, by strain gauges, to determine the occurrence of locations or sections of knotted spun yarn with reduced yarn strength, or so-called weak yarn.

[0014] In the solution of Patent Document 1, additional mechanical action on the spun yarn during production (increased friction and yarn load) can reduce the quality of the spun yarn during production, disrupt the continuity of spun yarn production, reduce the manufacturability of spun yarn production, or even affect subsequent processing of the spun yarn. The natural occurrence of impurities in the fiber production process can cause mechanical problems in the measuring element itself. Because it is a mechanical or mechatronic device, it is relatively expensive and has high demands in terms of servicing, adjusting for various types and finenesses of yarn produced, and the long-term stability of the yarn production process.

[0015] Many types of yarn sensors for monitoring yarns are generally known. Contact type yarn sensors are known as well as non-contact type yarn sensors, see the above-mentioned US Pat. No. 5,649,999.

[0016] Contact yarn sensors, i.e. sensors that require the yarn to be in direct contact with the sensor's measuring element during measurement to determine the yarn parameters, are primarily used in laboratories for additional yarn quality assessments, since the yarn needs to be stationary or move only at a limited speed during the measurement. However, as documented in US Pat. No. 5,629,499 demonstrates, contact yarn sensors are also used in yarn production on air-jet spinning machines, especially when there are no sufficiently reliable and powerful non-contact alternatives to yarn sensors.

[0017] Non-contact yarn sensors are based on different physical principles, such as capacitance sensors, ultrasonic sensors, charge sensors, or non-contact yarn sensors are based on optical principles.

[0018] Different types of optical yarn sensors are described in numerous documents, for example in US Pat. Nos. 5,611,299 to 5,729,102 and others.

[0019] A general drawback of the background art in the field of optical yarn sensors is their inability to monitor and evaluate the occurrence of the above-mentioned or mentioned structural defects, which primarily only appear during subsequent processing of the yarn. Neither the quantitative (mass or diameter) parameters (e.g., CV, IPI, yarn diameter, yarn fineness) that have been used so far for the non-contact evaluation of the quality of a knotted spun yarn, and that are essentially based on monitoring the mass and / or diameter properties and defects of the knotted spun yarn during its production, for example, on an air-jet spinning machine, nor the techniques for evaluating the hairiness of the knotted spun yarn while passing through a location or section of the knotted spun yarn with a structural defect, provide any substantial indication of either an increased likelihood of the occurrence of a particular structural defect in the knotted spun yarn at that particular location or section of the produced knotted spun yarn, or of the actual occurrence of a structural defect in the knotted spun yarn at that location. [Prior art documents] [Patent documents]

[0020] [Patent Document 1] European Patent No. 2565307 [Patent Document 2] Jiaotong Patent No. 306117 [Patent Document 3] Jiaotong Patent No. 305265 [Patent Document 4] European Patent No. 2827132 [Patent Document 5] U.S. Patent No. 371,274 [Patent Document 6] European Patent No. 0627623 [Patent Document 7] Patent No. 4756411 Specification [Patent Document 8] U.S. Patent No. 6,219,135 [Patent Document 9] U.S. Patent No. 5,270,787 [Patent Document 10] U.S. Patent No. 5,654,554 [Patent Document 11] U.S. Patent No. 5,521,395 [Patent Document 12] International Publication No. 2011 / 026249 [Non-patent literature]

[0021] [Non-Patent Document 1] Moaaz Ahmed Samy Moustafa Eldeeb, "Different Approaches for Predicting Air Jet Spun Yarn Strength," 2017 Summary of the Invention [Problem to be solved by the invention]

[0022] It is therefore an object of the present invention to eliminate or at least minimize the drawbacks of the prior art and in particular to provide a method, device, software and software carrier for contactless measurement of the occurrence of structural defects in shied spun yarns, i.e. yarns comprising a core from parallel fibres, the core being wound by a wrapping layer of fibres comprising wrapper fibres and coarse fibres. [Means for solving the problem]

[0023] The object of the present invention is achieved by a method for detecting structural defects in a bundled spun yarn, the yarn comprising a core formed by parallel fibers, the core being bound together by a wrapping layer of fibers comprising wrapper fibers and coarse fibers, the method comprising: capturing a moving yarn image over at least a portion of the yarn length by at least one optical sensor, the optical yarn sensor comprising at least one row of radiation sensitive elements and at least one radiation source; processing the captured yarn image by digital image analysis methods to obtain data relating to the yarn surface structure; evaluating the yarn surface structure along the yarn length from the obtained data; comparing changes in the yarn surface structure with preset criteria; and determining the relevant location in the yarn as the location of the occurrence of a structural defect in the yarn if the changes in the yarn surface structure exceed these preset criteria.

[0024] To simplify and speed up the method of capturing an image of a knotted spun yarn and the method of image analyzing this image of the knotted spun yarn to evaluate the occurrence of structural defects in the knotted spun yarn, it is advantageous that when the yarn image is captured by an optical yarn sensor along the yarn edge, the captured yarn image is processed by a digital image analysis method to obtain data regarding the yarn structure in the area along the yarn edge, and from the obtained data, changes in the yarn structure along the yarn edge are detected and evaluated, after which these changes in the yarn structure along the yarn edge are compared with predetermined criteria, and if these changes in the yarn structure along the yarn edge exceed the predetermined criteria, the relevant location in the yarn is classified as a location where a structural defect in the yarn occurs.

[0025] It is advantageous to capture images of spun skeins if the optical yarn sensor captures an image of the yarn envelope in a limited area of ​​the image field along the yarn edge, extending both within the yarn and in a zone outside the yarn, said zone being located along the yarn edge, while an analysis of lateral deviations of the image of the yarn envelope from the straight yarn direction is performed by digital image analysis methods and / or an analysis of disturbances in the yarn structure is performed.

[0026] According to one embodiment, to analyze the lateral deviation of the image of the bundled spun yarn envelope from the yarn straight direction, changes in the positions of the edges of the yarn image relative to the optical yarn sensor are evaluated, at least one frequency range of a spectrum of the positions of the yarn surface edges is determined or set, and the spectrum of the positions of the edges of the yarn image within the at least one determined or set frequency range is monitored and continuously evaluated. From the monitored and continuously evaluated spectrum of the positions of the edges of the yarn image within the at least one determined or set frequency range, the waviness of the yarn surface is determined as a function of the deviation of the yarn envelope from the yarn straight direction. The current lateral deviation of the image of the yarn envelope from the straight direction of the yarn is continuously statistically evaluated and compared with a reference value for the yarn surface waviness, the reference value for the yarn surface waviness being formed by a long-term average of the yarn surface waviness values ​​from the same spinning unit and / or a long-term average of the yarn surface waviness values ​​from multiple spinning units set to produce the same yarn, and / or the reference value for the yarn surface waviness is set according to current production or processing or measurement parameters at the spinning station of the air-jet spinning machine, for example by a central control system of the production or processing or measuring machine. A structural defect in the yarn is detected upon occurrence of a current deviation of the yarn surface waviness beyond a set decision threshold value relative to the reference value for the surface waviness.

[0027] According to one embodiment, the above-mentioned range of analyzed frequencies of the spectrum of the position of the edge of the spun yarn is set depending on the current yarn parameters, in particular the type of fibrous material for yarn production, the yarn movement speed, the spinning pressure in the spinning nozzle, the fineness of the spun yarn, and the current components of the spinning unit, in particular the type of spinning nozzle.

[0028] According to one embodiment, to analyze the irregularities in the cohesive spun yarn structure, at least one region for monitoring the image of the coarse fibers is determined or set on at least a portion of the yarn length that is important for monitoring the irregularities in the yarn structure, and the irregularities in this region are monitored and evaluated. From the irregularities in the yarn structure, the yarn roughness is determined as a function of the occurrence of irregularities in the cohesive spun yarn structure and / or as a function of the occurrence of irregularities in the cohesive spun yarn surface structure. The yarn roughness is monitored and compared with a reference value for the yarn roughness, which is a long-term average of the values ​​of the yarn roughness from the same spinning unit and / or a long-term average of the values ​​of the yarn roughness from multiple spinning units configured to produce the same yarn, and / or which is set according to the current production, processing, or measurement parameters of the production, processing, or measurement machine, and a structural defect in the yarn is detected upon the occurrence of a deviation of the current yarn roughness from the reference value for the yarn roughness that exceeds the set decision threshold.

[0029] The area for monitoring images of the coarse fibers of at least a portion of the length of the bundled spun yarn is set depending on the current yarn parameters, in particular the type of fibrous material for yarn production, the yarn movement speed, the spinning pressure in the spinning nozzle, the fineness of the spun yarn, and the current components of the spinning unit, in particular the type of spinning nozzle.

[0030] To increase the accuracy and reliability of detecting structural defects in spun yarns, an analysis of the lateral deviation of the image of the yarn envelope from the straight direction of the yarn and an analysis of the disturbances in the yarn structure are carried out simultaneously.

[0031] The optical yarn quality sensor senses at least one yarn diameter parameter, in particular the yarn diameter, for complex determination of the bundled spun yarn parameters simultaneously with capturing a yarn image for detecting structural defects in the yarn.

[0032] The principle of the device for detecting structural defects in bundled spun yarns, wherein the device comprises at least one optical yarn sensor having at least one row of radiation-sensitive elements and further comprises at least one radiation source, is that the device has means adapted to perform a method for detecting structural defects in bundled spun yarns according to the method described above.

[0033] From the point of view of efficient use of the working means of a production, processing or measuring machine, it is advantageous if the optical yarn sensor is formed by an optical yarn quality sensor.

[0034] In order to ensure the calculation and control performance of the device, it is advantageous if the means adapted to carry out the method for detecting structural defects in spun yarns according to the method described above comprise a microprocessor with memory, or a gate array, or a custom electronic circuit of the ASIC type, or a combination of at least two of these elements.

[0035] The principle of the computer program (product) is that it comprises instructions for causing a device according to the preceding paragraph to carry out the steps of the method for detecting structural defects in a shied spun yarn according to the preceding paragraph.

[0036] The principle of the computer-readable medium of the present invention is that it stores a computer program therein, the computer program comprising instructions for causing the device according to the preceding paragraph to carry out the steps of the method for detecting structural defects in a spun yarn device according to the preceding paragraph.

[0037] The present invention is based on the fact that the occurrence of structural defects in bundled spun yarns, i.e. yarns comprising a core formed by parallel fibers, which are bound together by a wrapping layer of fibers consisting of wrapper fibers and coarse fibers, can also be detected by optical yarn sensors by using a specific method for detailed processing of acquired data describing visual features or changes in visual features of the bundled spun yarn structure (in particular, the surface structure of the bundled spun yarn).From the changes in the characteristics of the yarn structure or yarn surface structure captured by the optical sensor, it is possible to determine such changes in yarn structure, or more specifically, such changes in yarn surface structure, and based on these changes, it is possible to determine locations or parts of the bundled spun yarn that belong to the category of locations or sections where structural yarn defects, so-called processing yarn defects, appear in the subsequent yarn treatment process following the yarn production itself, i.e., the processing stage of the yarn.

[0038] Thus, the method of the present invention does not detect yarn defects that affect yarn quality as described by traditional yarn quality parameters, such as the occurrence of thin and thick spots, hairiness, etc., but does detect defects that appear in short sections of a bundled spun yarn only upon subsequent processing of the yarn (e.g., during or after woven or knitted fabric production) due to their specific properties or manifestations when these previously hidden defects appear as optical differences in specific locations or regions on the woven or knitted fabric, for example, based on different colors of these different locations or sections of the previously indistinguishable yarn after dyeing, or due to different light reflectances from these previously indistinguishable locations or sections of the yarn. Such locations or sections of yarn with structural defects do not exhibit the typically monitored mass defects, yarn diameter defects, or yarn hairiness defects, and it should be noted that these locations with structural yarn defects generally have reduced axial strength, but even this reduced axial strength is still sufficient for yarn production and subsequent processing of such yarn. At the same time, however, it should be noted that if the fiber wrapping layer is not stable, uniform, etc., the yarn core will not be sufficiently compressed. As a result, the radial strength of the yarn will decrease, which will then lead to faster wear of the yarn as a manifestation of structural yarn defects. The radial strength of the yarn is evaluated, for example, by a rolling test. Naturally, optical yarn sensors cannot monitor the strength of the yarn during the production, processing, or analysis of the knotted spun yarn, nor can they monitor changes in the tension of the yarn during the production, processing, or analysis of the knotted spun yarn.

[0039] The solution according to the invention therefore works in conjunction with the fact that the occurrence of a section or section of yarn with a structural yarn defect is manifested by a local and short-term change in the structure and properties of the spun yarn, which in the subsequent processing of the yarn in which said section is mixed with a yarn without structural defects into a finished product (woven fabric) leads to the formation of a visible difference in the finished product. It should be noted that this visible difference is not caused by a difference in the strength of the yarn, but by a difference in the structure and properties of the spun yarn instead of a structural defect in the spun yarn.

[0040] It should be added that in principle, the optical monitoring and evaluation of yarn locations or sections with structural defects according to the present invention does not limit other monitoring processes and evaluations of yarn quality, performed optically or by other methods, such as monitoring yarn quality from the point of view of the occurrence of yarn mass or diameter defects, or from the point of view of yarn hairiness, etc. On the contrary, it can be said that the monitoring of yarns and evaluation of the occurrence of yarn locations or sections with structural defects by optical methods, which is the subject of the present invention, brings the evaluation of the quality of shied spun yarns to a whole new level, where the evaluation of the shied spun yarns becomes considerably more detailed, by focusing on the occurrence of abrupt changes in yarn structure or abrupt changes in the structure of the yarn surface, which are not currently applied during yarn production or in the subsequent processing or analysis of the shied spun yarns.

[0041] Therefore, the subject of a detailed analysis of the properties of the shied spun yarn according to the present invention is rapid changes in the structure of the shied spun yarn, in particular rapid changes in the surface structure of the shied spun yarn, either directly on the surface of the shied spun yarn and / or in very limited areas outside (above) the surface of the shied spun yarn, in particular changes in the wrapping of the yarn core with wrapper fibers and / or coarse fibers, and the occurrence of loose sections or free ends of coarse fibers, free ends of other yarn-forming fibers, and possible sagging of the yarn core as a result of insufficient wrapping. For the purposes of the present invention, these rapid changes in the surface structure of the shied spun yarn are fully characterized by changes in the yarn surface waviness and / or changes in the yarn surface roughness (disorder), and accordingly, such locations or sections of the shied spun yarn can be classified as locations or sections of the shied spun yarn with structural defects.

[0042] As can be seen from the nature of the problem, optical yarn sensors (especially optical yarn quality sensors for assessing yarn diameter defects and possibly also yarn hairiness) are well known in principle. These sensors can be used in the present invention as long as they allow for sufficiently detailed and rapid acquisition of yarn images and processing of the acquired image data relating to the visual features of the spun yarn structure (or more specifically, to the visual features of the surface structure of the spun yarn). Preferably, sensors are used in which one or more sensing elements provide sufficient resolution to capture detailed yarn images for assessing the surface structure of the spun yarn. Such one or more sensing elements are, for example, single or even multiple rows of light-sensing elements with a sufficient density of radiation-sensitive elements arranged in rows adjacent to one another in a direction transverse to the yarn movement path, such as in the spinning station of an air-jet spinning machine or in the working station of a winding machine. Another advantage of the solution according to the invention is the fact that image data relating to the visual features of the structure of the spun yarn bundle or the visual features of the surface structure of the spun yarn bundle are obtained by the optical yarn sensor without any additional mechanical components acting on the spun yarn bundle and therefore without being subjected to additional stresses, which makes it possible to maintain a high speed for the production, processing or measurement of the spun yarn bundle and not affect the quality of the produced, processed or measured spun yarn bundle. Also, changes and adjustments to the settings for the optical monitoring and evaluation of structural yarn defects in different types of spun yarn bundles can be made only by modifying the software and changing the relevant parameters of the evaluation algorithm in the device according to the invention, which is fast and relatively inexpensive. Another advantage is that the optical yarn sensor can be common to both the sensing of spun yarn bundles according to the invention and to previously used optical sensing and evaluation methods of yarn quality based on the principles of diameter defects, yarn hairiness, etc., which is economically advantageous and simplifies the structure of the work station (e.g. of a spinning unit of an air-jet spinning machine) or of a winding machine. At the same time, however, it should be noted that the present invention can also be implemented as a solution independent of existing means for assessing the quality of shied spun yarns.

[0043] In terms of image processing of the knotted spun yarn, digital image analysis (for example, but not limited to, a specific image analysis procedure based on the representation of the signal in the frequency domain, where this signal is understood as the sum of a series of appropriately selected periodic functions, a different approach from the standard approach where the output signal of the optical yarn image sensor is understood as a function of time) is used. In practice, the use of trigonometric functions (i.e., sine and cosine functions) has proven to be the most effective. To do this, a given output signal is decomposed into its harmonic components (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, The amplitude spectrum is the frequency dependence of the amplitude of a measurand. The frequency spectrum shows the frequencies of simple oscillatory movements that have the greatest influence on the resulting complex process. In our case, we could also use the so-called power spectrum, or in simple terms, "the power of the frequency components of a signal", which can be simplified as the square of the amplitude spectrum, but we must take into account the fact that the power spectrum shows the proportion of energy in a signal, which is a somewhat important difference from the classical approach using the frequency domain.

[0044] In our case, it is also possible to determine the frequency range of the frequency spectrum that is important for the purposes of the present invention and to determine the "energy" of this range of the power spectrum according to the manufacturing parameters of the spinning machine, winding machine, etc., e.g., spinning speed, moving speed of the spun yarn bundle, etc. Then it is possible to use the values ​​thus determined, e.g., to determine a measure of waviness of the yarn surface.

[0045] Another option is to use digital filters for signal processing: in this case, the input signal is processed by a digital band-pass filter, and only signals of a certain frequency are allowed to pass to the filter output, whereby the specific frequency is set according to the machine parameters or determined in an appropriate way.

[0046] For the purposes of the present invention, the waviness of the yarn surface means the deviation of the yarn envelope from the straight direction of the yarn. The waviness of the yarn surface, or the waviness of the yarn, is preferably determined by storing the position of the first, or possibly the last, consecutively shadowed radiation-sensitive element of the optical sensor from each image of the yarn on the linear optical sensor, thereby detecting the current position of the yarn edge and thus monitoring the yarn envelope, which is further analyzed by the method of the present invention. Furthermore, for each yarn image on the linear optical sensor, first, fibers protruding from the yarn core are filtered out, and then the position of the radiation-sensitive element shadowed by the optical sensor of at least one edge of the yarn core is determined. The positions of the yarn edges are saved, and the envelope of the yarn core is monitored. Subsequently, the envelope of the yarn core is analyzed according to the method of the present invention.

[0047] The term "shied spun yarn roughness" essentially describes a new qualitative parameter for the evaluation of shied spun yarns that differs from the qualitative parameters currently used for the evaluation of shied spun yarns and is also distinct from the parameter known as yarn hairiness. In principle, yarn roughness is a characteristic of shied spun yarns that describes and quantifies the occurrence of irregularities in the shied spun yarn structure, or more specifically, the occurrence of irregularities within the surface structure of the shied spun yarn, primarily due to irregularities in the wrapping of the yarn core by the fiber wrapping layer and other irregularities in the yarn structure itself. Thus, yarn roughness takes into account both the number of coarse fibers twisted into the yarn core, their number, and the orientation of loose fibers on the yarn core, as well as the occurrence of untwisted free ends or other portions of loose fibers. Furthermore, the yarn roughness parameter takes into account the occurrence of loose fibers on the yarn core due to insufficient local wrapping of the yarn core. Furthermore, the yarn roughness parameter also takes into account the occurrence of fibers protruding from the yarn core and entering the yarn hairiness evaluation area through a limited area along the edge of the yarn core. Thus, roughness of a shied spun yarn is a property that describes the degree of disorder in the yarn structure, or the degree of disorder in a short length section of the shied spun yarn.

[0048] One approach to monitoring and recognizing the structure of a knotted spun yarn is to monitor and recognize the untwisted free ends of the coarse fibers within a narrow band along the edge of the yarn core when a yarn image is captured by an optical yarn sensor, whether the yarn is shadowed by at least one row of radiation-sensitive elements of the optical sensor, or by reflecting radiant energy from the yarn and then incidenting the reflected radiant energy onto at least one row of radiation-sensitive elements of the optical sensor. From the captured yarn image, the location and extent (size, thickness, diameter) of the yarn core are identified, and any objects recorded within the set narrow band of the image along the identified yarn core are considered to be objects within the scope of the assessment of the roughness of the knotted spun yarn.

[0049] Another approach to monitoring and recognizing the structure of a shied spun yarn is to use image analysis of the yarn image to recognize the location and extent (size, thickness, diameter) of the yarn core, the untwisted free ends of the coarse fibers, as well as the coarse fibers wrapped around the yarn core, the free ends of the wrapper fibers, the free ends of the fibers protruding from the yarn core, etc., i.e., the irregularities located on the yarn surface.

[0050] Thereafter, for example, the number of active (shadowed or illuminated by radiant energy reflected from the yarn) radiation sensitive elements of the sensing element are summed, whereby the radiation sensitive elements are located outside the identified image of the yarn core within a narrow band set along the identified yarn core. Optionally, these irregularities are monitored within a narrow band set along the yarn core in the captured yarn image (e.g., even across several rows of sensing elements of the sensor), including image analysis of the overall yarn image that allows for recognition of irregularities, etc. in the structure of the spun bundle yarn along the entire width of the captured image of the spun bundle yarn.

[0051] As already mentioned above, image data relating to the spun yarn bundle, or more specifically image data relating to the surface structure of the spun yarn bundle, can also be obtained by a method of image analysis of a yarn image, from which data describing the visual features of the spun yarn bundle, or more specifically the visual features of the surface structure of the spun yarn bundle, are determined by the image analysis method, and these data are used by the method according to the invention to detect locations or sections of the spun yarn bundle having structural yarn defects. Image analysis is possible with the help of convolution methods, filtering methods, edge or object detection in images, etc., as described, for example, in the publication "Image Information Processing" by Klima, M., Bernas, M., Hozman, J., Dvorak, P., Textbook of CVUT, Prague 1996, and in the publication "An Introduction to Digital Image Processing" by Frederic Patin aka YOV408, http: / / teachme.free.fr / ImageProc.pdf, and in the publication "Metody obrazove analyzy dat" by O. Zmeskal, O. Sedlak, M. Nezadal (5 / 2002).

[0052] The invention is represented diagrammatically in the drawing. [Brief explanation of the drawings]

[0053] [Figure 1] 1 shows the configuration of an air jet spinning machine and one of its spinning stations. [Figure 2] 1 shows details of the general construction of an apparatus according to the present invention; [Figure 2a] 1 shows details of the construction of one embodiment of the device according to the present invention. [Figure 2b] 3 shows details of the construction of a second embodiment of the device according to the invention; [Figure 3] 1 shows an example of the structure of a spun yam and a part thereof according to the present invention. [Figure 4] 1 shows an example of a shied yarn structure having a structural defect. [Figure 5] 1 shows a schematic flow chart of the evaluation of structural defects in a shied spun yarn according to the present invention. [Figure 5a] 1 shows a detailed flowchart of the evaluation of structural defects in shied spun yarns according to the present invention. [Figure 6] 1 shows a spectrum of edge position (change in edge position) of a yarn surface in the frequency domain, along with one determined or set range of frequencies that are important for monitoring the spectrum of edge position (change in edge position) of the yarn surface. [Figure 7] 1 shows a captured image of an actual shied yarn that has undergone structural defect detection according to the present invention. [Figure 8a] For example, an image from the detection of an edge of an actual spun yarn bundle for the purposes of the present invention is shown, captured by the sensor configuration of FIG. 2a. [Figure 8b] For example, an image captured by the sensor configuration of FIG. 2b shows the detection of the yarn core, wrapper fibers, and coarse fibers of an actual shied spun yarn for the purposes of the present invention. [Figure 8c] 8a and 8b show an image captured from the detection of thread structure for the purposes of the present invention, produced by combining the captured images of FIG. 8a and FIG. 8b. DETAILED DESCRIPTION OF THE INVENTION

[0054] The present invention will be described with reference to an exemplary embodiment of a method for detecting structural defects in a bundled spun yarn 3 during its production in a spinning station 1 of an air-jet spinning machine. Nevertheless, the present invention is applicable to many other textile machines, in particular winding machines and machines for measuring the quality of the bundled spun yarn 3. Thus, the present invention is applicable not only to the online, non-contact detection of structural defects in a bundled spun yarn 3 during its production, but also to stages of subsequent processing of the bundled spun yarn 3, for example, when winding the bundled spun yarn 3, when processing the bundled spun yarn 3 into a subsequent product, etc.

[0055] When the term "yarn" alone is used in the following text, it means a "bundled spun yarn 3" comprising a core 30 formed by parallel fibers, which are bound together with a wrapping layer of fibers comprising wrapper fibers 31 and coarse fibers 32.

[0056] A method for detecting structural defects in a shied spun yarn 3, which comprises a core 30 formed by parallel fibers, the core 30 being interconnected with a wrapping layer of fibers comprising wrapper fibers 31 and coarse fibers 32, utilizes the fact that an image of the yarn 3 is captured by at least one optical sensor 6 of the yarn 3 along at least a portion of the length of the yarn 3. The optical yarn sensor 6 comprises at least one array 610 of radiation-sensitive elements 6100 and at least one radiation source 62, and the optical sensor 6 is connected to electronics 7 equipped with software. The captured image of the yarn 3 is processed by digital image analysis methods to obtain data on the surface structure of the yarn 3, and from these obtained data, changes in the surface structure of the yarn 3 along the length of the yarn 3 are evaluated. These changes in the surface structure of the yarn 3 are compared with predetermined criteria, and if these changes in the surface structure of the yarn 3 exceed the predetermined criteria, the relevant location of the yarn is determined as the location of the occurrence of a structural defect V in the shied spun yarn 3.

[0057] Preferably, the yarn optical sensor 6 captures an image of the bundled spun yarn 3 along the edge H of the yarn 3, and the captured image of the yarn 3 is processed by digital image analysis methods to obtain data on the structure of the yarn 3 along the yarn edge, and from the obtained data, changes in the yarn structure along the edge of the yarn 3 are evaluated. These changes in the yarn structure along the edge of the yarn 3 are compared with preset criteria, and if these changes in the structure of the yarn 3 surface along the yarn edge exceed the preset criteria, the relevant location of the yarn is determined as the location of the structural defect V in the bundled spun yarn 3.

[0058] It is advantageous if the optical yarn sensor 6 captures an image of the yarn envelope along the edge of the yarn 3 and an analysis of the lateral deviation of the image of the envelope of the yarn 3 from the straight direction of the yarn is performed by digital image analysis and / or an analysis of the degree of disorder of the yarn structure is performed.

[0059] To analyze the lateral deviation of the image of the yarn 3 envelope from the straight direction of the yarn 3, a change in the position of the edge H of the yarn image relative to the optical sensor 6 during yarn movement (e.g., during yarn production or yarn winding) is analyzed, whereby one range O of frequencies of the spectrum of the position of the edge H of the yarn 3 during yarn movement and a spectrum E of the position of the edge H of the image of the yarn 3 in at least one determined or set range O of frequencies are continuously monitored and evaluated. From the monitored and continuously evaluated spectrum E of the position of the edge H of the image of the yarn 3 in the at least one determined range O of frequencies, a waviness K of the surface of the yarn 3 is determined as a function of the deviation of the yarn 3 envelope from the straight direction of the yarn 3. The current lateral deviation of the image of the yarn 3 envelope from the straight direction of the yarn 3 is continuously statistically evaluated and compared with a reference value Kref of the yarn surface waviness K, the reference value Kref of the yarn 3 surface being formed as a long-term average of the values ​​of the yarn 3 surface waviness K from the same unit 1 and / or as a long-term average of the values ​​of the yarn 3 surface waviness K from multiple units 1 set to produce, process or measure the same yarn 3, and / or the reference value Kref of the yarn 3 surface waviness K is set according to current production or processing or measurement parameters of the production or processing or measuring machine, and a yarn structural defect V is detected upon the occurrence of a current deviation ΔK of the yarn 3 surface waviness K that exceeds a set decision threshold value relative to the reference value Kref of the yarn 3 waviness K.

[0060] According to one embodiment, the analyzed frequency range of the spectrum E at the position of the edge H of the bundled spun yarn 3 is set depending on the current yarn 3 parameters, in particular the type of fibrous material for the production of the yarn 3, the movement speed of the yarn 3, the spinning pressure in the spinning nozzle 20, the fineness of the spun yarn 3, and the current components of the spinning unit 2, in particular the type of spinning nozzle 20, etc.

[0061] To analyze the structural disturbances of the shied spun yarn 3, at least one frequency domain OL for monitoring images of the coarse fibers 32 over at least a portion of the length of the yarn 3, which domain OL is important for monitoring the structural disturbances of the yarn 3, is determined or set, and within this domain OL the structural disturbances of the shied spun yarn 3 are monitored and evaluated. From the structural disturbances of the yarn 3, the roughness W of the yarn 3 is determined as a function of the occurrence of irregularities in the structure of the shied spun yarn and / or as a function of the occurrence of irregularities in the surface structure of the shied spun yarn 3. The roughness W of the yarn 3 is monitored and compared with a reference value Wref of the roughness W of the yarn 3, the reference value Wref of the roughness W of the yarn 3 being formed as a long-term average of the values ​​of the roughness W of the yarn from the same unit 1 and / or as a long-term average of the values ​​of the roughness W of the yarn from multiple units 1 set to produce the same yarn, and / or the reference value Wref of the roughness W of the yarn 3 is set according to current production or processing or measurement parameters of the production or processing or measuring machine, and a structural defect V of the yarn is detected when a deviation ΔW of the current roughness W of the yarn from the reference value Wref of the roughness W of the yarn exceeds a set judgment threshold.

[0062] It is advantageous if the area OL for monitoring images of the coarse fibers 32 on at least part of the length of the bundled spun yarn 3 is set depending on the current yarn parameters 3, in particular the type of fibrous material 11, 14 for producing the yarn 3, the movement speed of the yarn 3, the spinning pressure in the spinning nozzle 20, the fineness of the spun yarn 3, and the current components of the spinning unit 2, in particular the type of spinning nozzle 20, etc.

[0063] The analysis of the lateral deviation of the image of the envelope of the bundled spun yarn 3 from the straight direction of the yarn 3 and the analysis of the disturbances in the yarn 3 structure are preferably carried out simultaneously in order to achieve more accurate results and increase the reliability of the detection of structural defects V in the yarn 3.

[0064] In order to efficiently use the means at the machine work station 1, at the same time as capturing an image of the bundled spun yarn 3 for detecting structural defects V in the yarn, at least one average parameter of the yarn 3, in particular the diameter Φ of the yarn 3, is sensed by an optical sensor 6 of the quality of the yarn 3.

[0065] The device for detecting structural defects V in a bundled spun yarn 3 comprises at least one optical sensor 6 of the yarn 3 with at least one row 610 of radiation-sensitive elements 6100. The device further comprises at least one radiation source 62 and also means adapted to perform a method for optical detection of structural defects V in the bundled spun yarn 3, for example during production of the bundled spun yarn 3 on an air-jet spinning machine or during winding of a previously produced yarn 3. According to a preferred embodiment, the optical yarn sensor 6 is formed by an optical yarn quality sensor. The means adapted to perform the method for optically detecting structural defects V in the bundled spun yarn 3, or electronics 7, comprise a microprocessor with memory, or a gate array, or a custom electronic circuit of the ASIC type, or a combination of at least two of these elements.

[0066] A computer program (product) for implementing the present invention comprises instructions for an apparatus for optical detection of structural defects in a shied spun yarn 3, which performs the steps of a method for optically detecting structural defects in a shied spun yarn 3. The computer program is preferably stored on a computer-readable medium.

[0067] The following description focuses on describing an example of an air-jet spinning machine configuration for producing a bundled spun yarn, the core 30 being formed by parallel fibers, the core 30 being wound by a wrapping layer of fibers including wrapper fibers 31 and coarse fibers 32, as well as describing an example of image acquisition and image processing of the yarn 3, and evaluation of the yarn 3 images for the purpose of optically detecting structural defects V in the yarn 3 during production of the bundled spun yarn 3 in the air-jet spinning machine. Suitably, the description can also be used for winding machines and other textile machines (e.g., specialized textile machines or measuring machines) that process or otherwise handle the bundled spun yarn 3.

[0068] The air jet spinning machine comprises at least one row of identical spinning stations 1 arranged adjacent to one another. Each spinning station 1 comprises a container of fibrous material for producing a spun spun yarn 3. The container is typically formed by a sliver can 10 in which a sliver 11 of fibre is stored. The spinning station 1 further comprises a drafting device 13 into which the sliver 11 is fed from the can 10 and which reduces the sliver 11 to a form 14 suitable for feeding it to a spinning nozzle 20 arranged in a spinning unit 2 which is part of the spinning station 1.

[0069] The spinning unit 2 is adapted to convert the fiber formation 14 in the spinning nozzle 20 into a yarn 3, which is withdrawn from the spinning unit 2 by a withdrawal mechanism 4 arranged in the direction of movement of the fibrous material at the spinning station 1, where it is already in the form of a yarn 3 downstream of the spinning unit 2. The spinning station 1 further comprises a traversing and winding device 5 for the yarn 3 onto a bobbin 50, which is arranged in the direction of movement of the fibrous material downstream of the withdrawal mechanism 4 for the yarn 3 at the spinning station 1, and which is adapted to traverse the yarn 3 across the width of the rotating bobbin 50 and wind the yarn 3 onto the rotating bobbin 50.

[0070] At least one optical sensor 6 for the yarn 3 is arranged between the outlet 21 for the yarn 3 from the spinning unit 2 and the device 5 for traversing and winding the yarn 3 onto the bobbin 50. The optical sensor 6 for the yarn 3 is adapted for optical sensing of the yarn 3 during its production at the spinning station 1 of the air-jet spinning machine, i.e., for capturing images of the yarn 3 during its production. The optical sensor 6 for the yarn 3 is connected to an electronic device 7 equipped with software. The optical sensor 6 for the yarn 3 and the electronic device 7 are adapted to capture and process the yarn images according to the invention, i.e., to obtain and process information about the visual characteristics of the bundled spun yarn 3, more specifically, data about the visual characteristics of the surface structure of the bundled spun yarn provided by the optical sensor 6, whether in the form of yarn images or in the form of output signals corresponding to some of the monitored parameters, both for the detection of structural defects in the yarn 3 during its production at the spinning station 1 of the air-jet spinning machine.

[0071] The optical sensor 6 typically comprises at least one radiation source 60 arranged at a suitable position relative to the yarn 3 or relative to the path of the yarn 3 passing the optical sensor 6. The optical sensor 6 further comprises a light-sensitive element 61, relative to which the radiation source 60 is also suitably arranged.

[0072] 1 and 2a, the radiation source 60 is positioned opposite the sensing element 61, and a measurement slot 62 is positioned between the radiation source 60 and the sensing element 61 for the yarn 3 to pass through while sensing the yarn 3 during production of the yarn 3. Thus, the yarn 3 passes through the measurement slot 62 while being sensed at the spinning station 1 during yarn production.

[0073] In another exemplary embodiment, there is another suitable mutual arrangement of the radiation source 60, the sensing element 61, and the path of the yarn 3, i.e., the position of the yarn 3 to be sensed during the production of the yarn 3, including, for example, an arrangement for sensing the yarn 3 by means of radiant energy emitted by the radiation source 60 and reflected from the yarn 3 located in the measurement space in front of the sensing element 61, wherein the radiation source 60 is located on the same side of the yarn 3 as the sensing element 61, in other words, the radiation source 60 here irradiates the yarn 3 from the same direction as the sensing element 61 is pointed towards the yarn, including an embodiment shown in FIG. 2b.

[0074] In one exemplary embodiment not shown, the optical sensor 6 comprises at least a pair of radiation sources 60, one radiation source 60 arranged opposite the sensing element 61, with the measurement slot 62 arranged between this radiation source 60 and the sensing element 61, and the other radiation source 60 arranged on the same side of the yarn 3 as the sensing element 61, i.e., here the radiation source 60 irradiates the yarn 3 from the same direction as the sensing element 61 is directed towards the yarn. This is therefore essentially a combination of the radiation sources 60 of the embodiment shown in FIG. 2a and the embodiment shown in FIG. 2b. This combination of radiation sources 60 is advantageous, since the radiation source 60 arranged opposite the sensing element 61 (see FIG. 2a) serves to generate an outline of the yarn 3 on the sensing element 61, while the radiation source 60 arranged in the same direction as the sensing element 61 (see FIG. 2b) serves to sense the radiant energy reflected from the yarn 3 and incident on the sensing element 61. The two radiation sources 60 mentioned above are synchronized with each other in this case, so that the radiation energy emitted by them changes alternately rapidly, so that one sensing element 61 can detect the contour of the yarn 3, i.e., the edges H, their lateral displacement, the occurrence and parameters of the irregularities of the yarn 3 structure at the protrusions on the surface of the yarn 3, such as the wrapper fibers 31, the coarse fibers 32, the free ends 320 of the coarse fibers, the slack portions 321 of the coarse fibers 32, the short slack portions LN of the core 30 of the yarn 3, the protruding ends 310 of the wrapper fibers 31, the fibers of the core 30 of the yarn 3. 8a), but also the visual appearance of the yarn 3 structure from the side facing the sensing element 61, i.e., the wrapping of the core 30 of the yarn 3 with the wrapper fibers 31 and the coarse fibers 32, as well as the wrapper fibers 31 themselves, the coarse fibers 32 themselves, the free ends 320 of the coarse fibers 32, the loose portions 321 of the coarse fibers 32, the short loose portions LN of the core 30 of the yarn 3, the protruding ends 310 of the wrapper fibers 31, the protruding ends 300 of the fibers of the core 30 of the yarn 3, etc. (see FIG. 8b). In order to process the yarn images and the obtained visual data regarding the structure of the produced bundled spun yarn 3, these results of image acquisition of the bundled spun yarn 3 can then be processed separately (see FIGS. 8a and 8b) or it may be advantageous to combine them (see FIG. 8c) and process them together.

[0075] The radiation source 60 is formed by a suitable radiation emitter (e.g. point or multi-point or plane, etc.), optionally preceded by suitable optics for optimizing the radiation direction and improving the process of sensing the yarn 3. For example, in the embodiment of Fig. 2a, the point radiation emitter is preceded by a collimating optics 600 or the like for collimating the light beam from the radiation source 60 through the measurement slot 62 to the sensing element 61.

[0076] The sensing element 61 includes at least one row 610 of radiation sensitive elements 6100 (pixels) arranged adjacent to each other, the row 610 of radiation sensitive elements 6100 having a length L arranged approximately transverse to the yarn 3, and in the illustrated embodiment, the row 610 of radiation sensitive elements 6100 having a length L arranged approximately transverse to the direction of movement P of the yarn 3 during production of the yarn 3, i.e., transverse to the path of the yarn 3 during production of the yarn 3.

[0077] In an exemplary embodiment not shown, the yarn sensor 6 comprises at least two sensing elements 61 each having at least one row 610 of radiation-sensitive elements 6100 arranged next to each other, the at least two sensing elements 61 being spatially oriented relative to each other and relative to the yarn path 3, i.e. relative to each other and relative to the sensed yarn 3, at the spinning station 1 of the air jet spinning machine, thereby making it possible to capture multidimensional images of the yarn 3 and to perform multidimensional processing of the results of the images of the yarn 3 thus captured, which particularly contributes to increasing the accuracy of determining the occurrence of locations or sections of the yarn 3 having structural defects V.

[0078] In another exemplary embodiment not shown, sensors of physically different yarns 3 (e.g. yarn 3 tension sensors, capacitive yarn sensors, yarn vibration sensors, acoustic yarn sensors, etc.) are assigned to the optical yarn sensor 6, which makes it possible to combine the optical principle of sensing structural defects in the yarn 3 according to the present invention with the sensing of physically different yarns 3 appropriately and according to current needs.

[0079] Preferably, the optical yarn 3 sensor 6 consists of an optical sensor of yarn 3 quality, which is able to provide comprehensive and detailed data on the visual appearance of the sensed yarn 3, i.e. it is able to capture yarn images of the required quality and at the required speed.

[0080] The electronics 7 with software comprises hardware elements that provide the computing power and logical operations for processing the images of the output yarn 3 captured by the optical sensor 6 and for executing software operations for detecting structural defects V in the yarn 3 during production of the yarn 3 in the first station of the air jet spinning machine.

[0081] Advantageously, the electronics 7 comprise a microprocessor with memory, or a gate array, or a custom electronic circuit of ASIC type, or a suitable combination of at least two of these elements (i.e. a microprocessor, a gate array, or a custom electronic circuit of ASIC type), thus constituting means adapted to perform software operations to process images of the output yarn 3 captured by the optical sensor 6 and to detect structural defects V of the yarn 3 during yarn production in the spinning station 1 of the air jet spinning machine.

[0082] The software contained in a computer-readable medium that is part of the electronic device 7 is provided with program blocks or instructions that cause the entire device for detecting structural defects V in yarn 3 of the present invention, including at least one optical sensor 6 of yarn 3, adapted to process images of yarn 3 captured by the optical sensor 6 and to execute software operations for detecting structural defects V in the yarn, and having at least one row 610 of radiation-sensitive elements 6100 arranged adjacent to each other and connected to the electronic device 7 by software, to operate according to the required method, i.e., to perform the steps of the method of the present invention.

[0083] The computer readable medium of the present invention includes the computer program and software according to the above paragraphs.

[0084] For example, a bundled spun yarn 3 produced at spinning station 1 of an air-jet spinning machine includes a core 30 formed by a bundle of generally parallel fibers, the core 30 of the yarn 3 being wrapped with a wrapping layer of fibers including wrapper fibers 31 and coarse fibers 32. The wrapper fibers 31 are wound helically around the core 30 of the yarn 3, with the helices having a relatively regular pitch R. The coarse fibers 32 are also wound helically around the core 30 of the yarn 3, but these helices have an irregular pitch that varies along the core 30 of the yarn 3, as shown in FIG. 3 by the symbols R1, R2, and R3, or the coarse fibers 32 have incomplete wrapping around the core 30 of the yarn 3, thus forming untwisted (free) ends 320 protruding from the core 30 of the yarn 3. Alternatively, the coarse fibers 3 have loose portions 321 that form tufts or loops on the yarn surface. The shied spun yarn also shows short slack portions LN of the yarn 3 core, protruding ends 310 of wrapper fibers 31, protruding ends 300 of core fibers 30 of yarn 3, etc., and protruding or free ends 300, 310, and 320.

[0085] An example application of the present invention in the production of a shied spun yarn 3 at a spinning station 1 of an air-jet spinning machine is that an image of at least a portion of the length of the moving shied spun yarn 3 is captured by an optical yarn 3 sensor 6, thereby obtaining data D1 relating to the appearance (image) of the yarn 3, i.e., data relating to the visual appearance of the yarn 3, more specifically, data relating to the visual structure of the yarn 3. From these data D1, descriptive data D2 are subsequently extracted, which describe how the core 30 of the yarn 3 is wrapped by the wrapper fibers 31 and / or coarse fibers 32, i.e., what the visual structure of the yarn 3 is. From the extracted descriptive data D2, the wrapping S of the core 30 of the yarn 3 by the wrapper fibers 31 and / or coarse fibers 32 is determined. The wrapping S of the core 30 of the yarn 3 by the wrapper fibers 31 and / or coarse fibers 32 is determined continuously during the production of the yarn 3 at the spinning station 1 of the air-jet spinning machine, whereby changes in the wrapping S of the core 30 of the yarn 3 by the wrapper fibers 31 and / or coarse fibers 32 are detected. If a change in the wrapping S of the core 30 of the yarn 3 by the wrapper fibers 31 and / or the coarse fibers 32 is detected, i.e., discovered, the corresponding location of the structural defect V in the yarn 3 is determined, for example, as shown in Figure 4.

[0086] Furthermore, due to the speed of movement of the yarn 3 in the spinning station 1 of the air jet spinning machine, it appears possible to very well determine the wrapping S of the core 30 of the yarn 3 by the wrapper fibers 31 and / or coarse fibers 32 from the surface structure of the yarn 3, i.e. from visual changes in the structure of the surface of the yarn 3 in the vicinity of the edge H of the yarn 3, from the movement of the edge H of the yarn 3, etc. (all this within a monitoring zone Z along the yarn 3 or within the envelope of the yarn 3).

[0087] It appears that the determination of the visual changes in the surface structure of the yarn 3 can be carried out by carrying out an analysis of the surface structure of the yarn 3 with the aim of determining the waviness K of the surface of the yarn 3 and / or determining the roughness W of the yarn 3 from the properties of the coarse fibers 32.

[0088] If a deviation ΔK in the surface waviness K of the yarn 3 is detected, e.g., greater than a set decision threshold, e.g., greater than 5%, compared to the long-term statistical average of the surface waviness K of the yarn 3, and / or if a deviation ΔH in the roughness W of the yarn 3 is detected, e.g., greater than a set decision threshold, e.g., greater than 5%, compared to the long-term statistical average of the roughness W of the yarn 3, the corresponding occurrence location of the structural defect V of the yarn 3 is determined, e.g., as shown in FIG. 4.

[0089] The waviness K of the surface of the bundled spun yarn can be well determined in the frequency domain of the spectrum E of the position of the edge H of the surface of the yarn 3 in the width direction of the sensing elements 61 of the optical sensor 6 or in the length direction of at least one row 610 of elements 6100 of the sensing elements 61 of the optical sensor 6 of the yarn 3 arranged next to each other. In this frequency domain, at least one range O of frequencies is determined or set, which frequencies are important for monitoring the spectrum E of the position of the edge H of the surface of the yarn 3 (change in the edge position ΔH), and this spectrum E of the position of the edge H of the surface of the yarn 3 in at least one determined or set range O is monitored and continuously evaluated. From monitoring and continuous evaluation of the spectrum E of the position of the edge H of the yarn 3 surface in at least one determination or set range O of frequency, the waviness K of the yarn 3 surface is determined, which essentially describes the behavior of the pitch R of the spiral of the wrapper fiber 31 on the core 30 of the yarn 3 in the length direction, or the direction of the sensed movement P of the yarn 3, i.e., it essentially describes the wrapping of the core 30 of the yarn 3 by the wrapper fiber 31.

[0090] Improved determination of the corresponding occurrence locations of structural defects in the yarn 3 is performed by monitoring and continuous statistical evaluation of the deviation ΔK of the current waviness K of the yarn 3 surface from a reference waviness Kref of the yarn 3 surface. The reference waviness Kref of the yarn 3 surface is determined as a long-term average of the waviness K of the yarn 3 surface from the same spinning unit 2 and / or as a long-term average of the waviness K of the yarn 3 surface from multiple spinning stations 2 set to produce the same yarn 3, and / or the reference waviness Kref of the yarn 3 surface is set according to current production parameters at the spinning station 1 of the air-jet spinning machine.

[0091] In order to detect the location of the structural defect V in the yarn, the occurrence of a deviation ΔK of the currently detected waviness K of the surface of the yarn 3 from a set threshold value, for example a deviation of more than 5%, is detected.

[0092] According to another embodiment of the present invention, which uses the determination of the waviness K of the surface of the yarn 3 in the width direction of the sensing element 61 of the optical sensor 6 in the frequency domain of the spectrum E of the position of the edge H of the yarn 3 surface in the width direction, the setting of at least one frequency range O important for monitoring the spectrum E of the position of the edge H of the yarn surface (change in the edge position ΔH) compared to the long-term average of the spectrum E of the position of the edge H of the yarn surface is carried out depending on the current production parameters of the yarn 3, in particular the type of fibrous material 11, 14 for producing the yarn 3, the movement speed of the yarn 3, the spinning pressure in the spinning nozzle 20, the fineness of the spun yarn 3, and depending on the current components of the spinning unit 2, in particular the type of spinning nozzle 20.

[0093] The wrapping S of the core 30 of the yarn 3 can be well determined by determining the roughness W of the yarn 3, which in principle evaluates the degree of structural disturbance of the yarn 3, and this evaluation includes evaluating the wrapping of the core 30 of the yarn 3 by the wrapper fibers 31 and the coarse fibers 32, as well as the wrapper fibers 31 themselves, the coarse fibers themselves, the free ends 320 of the coarse fibers 32, the slack portions 321 of the coarse fibers 32, the short slack portions LN of the core 30 of the yarn 3, the protruding ends 310 of the wrapper fibers 31, the protruding ends 300 of the core 30 fibers of the yarn 3, etc., all within the time domain of the spectrum of the coarse fibers 32, where at least one region OL important for monitoring the structural disturbance of the yarn 3, represented by the above-mentioned parameters, is determined or set in a limited region Z along the edge H of the core 30 of the yarn 3. In this determined or set area OL of the spectrum of disturbances in the structure 3 of the yarn 3, the wrapping of the core 30 of the yarn 3, i.e., the wrapping of the core 30 of the yarn 3 by the wrapper fibers 31 and the coarse fibers 32, the wrapper fibers 31 themselves, the coarse fibers themselves, the free ends 320 of the coarse fibers 32, the slack portions 321 of the coarse fibers 32, the short slack portions LN of the core 30 of the yarn 3, the protruding ends 310 of the wrapper fibers 31, the protruding ends 300 of the fibers of the core 30 of the yarn 3, etc. are monitored and evaluated.

[0094] The roughness W of the bundled spun yarn 3 is used to assess structural defects of the yarn 3 in accordance with the present invention by monitoring and continuously statistically evaluating the deviation ΔW of the roughness W of the current yarn 3 from a reference value Wref of the roughness of the yarn 3. The reference value Wref of the roughness of the yarn 3 is a long-term average of the roughness W of the yarns 3 from the same spinning unit 2 and / or is a long-term average of the roughness W of the yarns 3 from multiple spinning stations 2 set to produce the same yarn 3, and / or the reference value Wref of the roughness of the yarn 3 is set according to the current production parameters at the spinning station 1 of the air-jet spinning machine.

[0095] For a simple and quick evaluation, the occurrence of a deviation ΔW of the roughness W of the yarn 3 exceeding a set decision threshold, for example exceeding 5%, is detected in order to determine the occurrence of a structural defect V in the yarn 3.

[0096] In order to facilitate the setting of the detection of the occurrence of structural defects V of the yarn 3, according to another embodiment of the present invention, the setting of the critical areas for determining the roughness value W of the yarn 3 is carried out according to the current production parameters of the yarn 3, in particular the type of fibrous material 11, 14 for the production of the yarn 3, the movement speed of the yarn 3, the spinning pressure in the spinning nozzle 20, the fineness of the spun yarn 3, and according to the current components of the spinning unit 2, in particular the type of spinning nozzle 20, etc.

[0097] In order to improve the accuracy of detecting structural defects V of the yarn 3, the waviness K of the surface of the yarn 3 and the roughness W of the yarn 3 are continuously monitored, and the overall wrapping KWS of the core 30 of the yarn 3 by the wrapper fibers 31 and the coarse fibers 32 is determined from the deviation of the waviness K of the surface of the yarn 3 and from the deviation of the roughness W of the yarn 3.

[0098] To detect a structural defect V of the yarn 3, a deviation ΔKWS of the current overall wrapping KWS of the core 30 of the yarn 3 from a reference degree KWSref of the overall wrapping KWS of the core 30 of the yarn 3 is monitored and continuously statistically evaluated. The reference degree KWSref of the overall wrapping KWS of the core 30 of the yarn 3 is a long-term average of the overall wrapping KWS of the core 30 of the yarn 3 produced in the same spinning unit 2, and / or is a long-term average of the overall wrapping KWS of the core 30 of the yarn 3 produced in multiple spinning stations 2 set to produce the same yarn 3, and / or the overall wrapping KWS of the core 30 of the yarn 3 is set according to current production parameters at the spinning stations of the air-jet spinning machine.

[0099] In another exemplary embodiment, the spun bundled yarn 3 is sensed by an optical yarn 3 quality sensor 6 that simultaneously senses at least one diameter parameter of the yarn 3, in particular the diameter Φ of the yarn 3. [Industrial Applicability]

[0100] The present invention is applicable to air jet spinning machines in the production of spun bundle yarns, and it is also applicable to winding machines and in principle generally to other types of textile machinery for producing and / or processing and / or analyzing or measuring spun bundle yarns, where it is necessary or desirable to evaluate the produced and / or processed spun bundle yarns not only in terms of diameter properties and hairiness, but also in terms of changes in the produced and / or processed yarn structure. [Explanation of symbols]

[0101] 1 Spinning Station 10 sliver cans 11 Sliver 13 Draft device 14 Fibrous formations 2 spinning units 20 Spinning nozzle 21 Yarn exit from spinning nozzle 3. Bundled spun yarn 30 Bundled spun yarn core 300 Protruding end of bundled spun yarn core 31 Wrapper Fiber 310 Protruding end of wrapper fiber 32 Crude Fiber 320 Free ends of crude fibers 321 loose part of crude fiber 4. Drawer mechanism 5 Winding device 50 bobbins 6 Optical yarn sensor 60 Radiation source 600 Collimation Optics 61 Light-sensing element 610 A row of radiation-sensitive elements arranged side by side 6100 Radiation-sensitive element 62 measurement slots 7 Electronic equipment D1 Data on the visual appearance of the yarn (related to the yarn image) D2 Descriptive data on how the wrapper fibers and / or coarse fibers wrap the yarn core or what the visual structure of the yarn is. E: Spectrum of the edge position of the yarn surface in the width direction of the sensing element of the optical sensor Φ Thread diameter H thread edge ΔH Change in position of yarn edge K Surface waviness of yarn ΔK Deviation of waviness on yarn surface Kref Reference waviness of yarn surface KWS wrapper fibers and coarse fibers for complete wrapping of the yarn core ΔKWS Standard overall wrapping of yarn core L is the length of the array of radiation-sensitive elements LN Short section of slack in yarn core O The frequency range that is important for monitoring the edge position spectrum (change in edge position) of the yarn surface OL: A frequency region important for monitoring the disturbance of the yarn structure in the time domain of the spectrum of the coarse fibers in a limited area along the edge of the yarn core. P: Direction of yarn movement during production R is the pitch of the wrapper fiber helix R1, R2, R3 Pitch of the crude fiber spiral S Wrapping of yarn core V Structural defects of the thread W Thread roughness ΔW Deviation of yarn roughness Wref Reference thread roughness Z-string monitoring zone

Claims

1. A method for detecting structural defects (V) in a shied spun yarn (3) comprising a core (30) formed by parallel fibers, comprising: The cores (30) are bound together by a wrapping layer (S) of fibers comprising wrapper fibers (31) and coarse fibers (32), the coarse fibers (32) being wound helically around the cores (30) with a variable pitch (R, R1, R2, R3) or with a variable direction, or with some of the coarse fibers (32) being incompletely wound around the cores (30); The structural defect (V) of the shied spun yarn (3) is insufficient strength of the shied spun yarn (3) at a specific location or portion and / or insufficient appearance of the shied spun yarn (3) at a specific location or portion, all of which do not significantly affect the mass and / or diameter characteristics of the shied spun yarn (3) or the yarn hairiness parameters at the specific location or portion of the shied spun yarn (3), The method comprises: an image of the moving spun bundle (3) is captured by at least one optical sensor (6) over at least a portion of the length of said spun bundle (3); The optical sensor (6) comprises at least one row (610) of radiation sensitive elements (6100) and at least one radiation source (60); The optical sensor (6) is connected to an electronic device (7) equipped with software, The captured image of the shied spun yarn (3) is processed by a digital image analysis method to obtain data on the surface structure of the shied spun yarn (3); From the acquired data, evaluating the changes in the surface structure of the shive yarn (3) along the length of the shive yarn (3), These changes in the surface structure of the spun shives (3) are compared with a predetermined standard, If these changes in the surface structure of the shied yarn (3) exceed the predetermined criteria, the relevant location of the shied yarn (3) is determined as the location of the structural defect (V) of the shied yarn (3), The optical sensor (6) captures an image of the spun bundle (3) along the edge (H) of the spun bundle (3); processing the captured image of the shied yarn (3) using digital image analysis methods to obtain data relating to the surface structure of the shied yarn (3) along the edge (H) of the shied yarn (3); From the acquired data, the change in the surface structure of the shied yarn (3) along the edge (H) of the shied yarn (3) is evaluated; These changes in the surface structure of the spun yam bundle (3) along the edge (H) of the spun yam bundle (3) are compared with a predetermined standard, If these changes in the surface structure of the shied yarn (3) along the edge (H) of the shied yarn (3) exceed the predetermined criteria, the relevant location of the shied yarn (3) is determined as the location of the structural defect (V) of the shied yarn (3), From the captured image of the spun yam (3) along the edge (H) of the spun yam (3), A lateral deviation of the surface of the spun yam bundle (3) from the straight direction of the spun yam bundle (3) is detected; The lateral deviation of the surface of the spun spun bundle (3) from the straight direction of the spun spun bundle (3) and the change ΔH in the position of the edge (H) of the yarn image relative to the optical sensor (6) are analyzed and evaluated, At least one range (O) of frequencies of the spectrum (E) at the position of the surface edge (H) of the spun yarn (3) is determined or set; The spectrum (E) of the position of the edge (H) of the surface of the spun yarn (3) within the at least one determined or set frequency range (O) is monitored and continuously evaluated; From the monitored and continuously evaluated spectrum (E) of the positions of the edges (H) of the surface of the shied yarn (3) within the at least one determined or set frequency range (O), a waviness of the yarn surface is determined as a function of the deviation of the surface of the shied yarn (3) from a straight direction of the shied yarn (3), the current lateral deviation of the surface of the shied spun yarn (3) from the straight direction of the shied spun yarn (3) is continuously statistically evaluated and compared with a reference value of the yarn surface waviness, the reference value of the yarn surface waviness being formed by a long-term average of the yarn surface waviness values ​​from the same unit and / or a long-term average of the yarn surface waviness values ​​from a plurality of units set up to produce, process or analyze the same shied spun yarn (3), and / or the reference value of the yarn surface waviness is set according to the current production, processing or measurement parameters of a production, processing or measurement machine, A structural defect (V) of the shied spun yarn (3) is detected when a current deviation of the yarn surface waviness from the reference value of the yarn surface waviness exceeds a set decision threshold.

2. The change ΔH in the position of the edge (H) in the time domain is transformed into the frequency domain to generate a frequency spectrum (E) of the position of the edge (H) of the shivering yarn (3); 2. The method according to claim 1, wherein the function of the deviation of the shied yarn (3) from its straight direction is defined as the energy of the spectrum (E) of the analyzed frequency range (O).

3. 3. The method according to claim 1 or 2, wherein the analyzed frequency range (O) of the spectrum (E) of the position of the edge (H) on the surface of the spun yarn (3) is set depending on the current yarn parameters, in particular the type of fibrous material for yarn production, the yarn movement speed, the spinning pressure in the spinning nozzle (20), the spun yarn fineness, and the current components of the spinning unit (2), in particular the type of spinning nozzle (20).

4. A method for detecting structural defects (V) in a bundled spun yarn (3) having a core (30) formed by parallel fibers, comprising: The cores (30) are bound together by a wrapping layer (S) of fibers comprising wrapper fibers (31) and coarse fibers (32), the coarse fibers (32) being wound helically around the cores (30) with a variable pitch (R, R1, R2, R3) or with a variable direction, or with some of the coarse fibers (32) being incompletely wound around the cores (30); The structural defect (V) of the shied spun yarn (3) is insufficient strength of the shied spun yarn (3) at a specific location or portion and / or insufficient appearance of the shied spun yarn (3) at a specific location or portion, all of which do not significantly affect the mass and / or diameter characteristics of the shied spun yarn (3) or the yarn hairiness parameters at the specific location or portion of the shied spun yarn (3), The method comprises: an image of the moving spun bundle (3) is captured by at least one optical sensor (6) over at least a portion of the length of said spun bundle (3); The optical sensor (6) comprises at least one row (610) of radiation sensitive elements (6100) and at least one radiation source (60); The optical sensor (6) is connected to an electronic device (7) equipped with software, The captured image of the shied spun yarn (3) is processed by a digital image analysis method to obtain data on the surface structure of the shied spun yarn (3); From the acquired data, evaluating the changes in the surface structure of the shive yarn (3) along the length of the shive yarn (3), These changes in the surface structure of the spun shives (3) are compared with a predetermined standard, If these changes in the surface structure of the shied yarn (3) exceed the predetermined criteria, the relevant location of the shied yarn (3) is determined as the location of the structural defect (V) of the shied yarn (3), The optical sensor (6) captures an image of the spun bundle (3) along the edge (H) of the spun bundle (3); processing the captured image of the shied yarn (3) using digital image analysis methods to obtain data relating to the surface structure of the shied yarn (3) along the edge (H) of the shied yarn (3); From the acquired data, the change in the surface structure of the shied yarn (3) along the edge (H) of the shied yarn (3) is evaluated; These changes in the surface structure of the spun yam bundle (3) along the edge (H) of the spun yam bundle (3) are compared with a predetermined standard, If these changes in the surface structure of the shied yarn (3) along the edge (H) of the shied yarn (3) exceed the predetermined criteria, the relevant location of the shied yarn (3) is determined as the location of the structural defect (V) of the shied yarn (3), A disturbance in the structure of the spun bundle (3) is detected from an image of the spun bundle (3) captured along the edge (H) of the spun bundle (3); The structural disturbance of the shied yarn (3) is analyzed to determine or set at least one area for monitoring an image of the coarse fibers (32) of at least a part of the length of the shied yarn (3), which is important for monitoring the structural disturbance of the shied yarn (3); In this area, the disturbance of the shied yarn (3) is monitored and evaluated, From the disturbance of the surface structure of the spun shied yarn (3), the roughness of the yarn is determined as a function of the occurrence of irregularities in the surface structure of the spun shied yarn (3), the roughness of the yarn is monitored and compared with a reference value of the roughness of the yarn, the reference value of the roughness of the yarn being a long-term average of the roughness values ​​of the yarn from the same unit and / or a long-term average of the roughness values ​​of the yarn from a plurality of units (2) set to produce or process or measure the same spun yarn bundle (3), and / or the reference value of the roughness of the yarn is set according to the current production or processing or measurement parameters of a production or processing or measurement machine, A structural defect (V) of the shied spun yarn (3) is detected upon occurrence of a current deviation of the yarn roughness from the reference value of the yarn roughness exceeding a set decision threshold.

5. 5. The method according to claim 4, wherein the area for monitoring the image of the coarse fibers (32) of at least a portion of the length of the bundled spun yarn (3) is set depending on the current yarn parameters, in particular the type of fibrous material for yarn production, the movement speed of the bundled spun yarn (3), the spinning pressure in the spinning nozzle (20), the fineness of the bundled spun yarn (3), as well as the current components of the spinning unit (2), in particular the type of spinning nozzle (20).

6. 6. The method according to claim 1, wherein an optical sensor (6) senses at least one yarn diameter parameter, in particular a yarn diameter (φ), simultaneously with the capture of an image of the shied spun yarn (3) for detecting structural defects (V) in the shied spun yarn (3).

7. 1. A device for detecting structural defects (V) in a shied spun yarn (3), comprising: The structural defect (V) of the shied spun yarn (3) is insufficient strength of the shied spun yarn (3) at a specific location or portion and / or insufficient appearance of the shied spun yarn (3) at a specific location or portion, all of which do not significantly affect the mass and / or diameter characteristics of the shied spun yarn (3) or the yarn hairiness parameters at the specific location or portion of the shied spun yarn (3), 10. An apparatus for detecting structural defects in a bundled spun yarn (3), comprising at least one optical sensor (6) having at least one row (610) of radiation-sensitive elements (6100), and further comprising at least one radiation source (60), as well as means adapted to perform the method according to any one of claims 1 to 6.

8. 8. Device according to claim 7, characterized in that the optical sensor (6) is formed by an optical yarn quality sensor.

9. Apparatus according to claim 7 or 8, characterized in that the means adapted to carry out the method according to any one of claims 1 to 6 comprise a microprocessor with memory, or a gate array, or a custom electronic circuit of the ASIC type, or a combination of at least two of these elements.

10. A computer program comprising instructions for causing an apparatus according to any one of claims 7 to 9 to carry out the steps of the method according to any one of claims 1 to 6.

11. A computer readable medium having stored thereon the computer program of claim 10.

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