Title of Invention

PROCESS AND DEVICE FOR CLEANING YARN

Abstract

ABSTRACT (IN/PCT/2001/01607/CHE) "PROCESS AND DEVICE FOR CLEANING YARN" A method for cleaning yarn by cutting out defects in the yarn using a cleaning limit for separating defects which are to be cut out from defects which are not to be cut out, wherein a cleaning limit for eliminating at least one defect in a yam according to its length and thickness is selected, a database of yarn defect images is established and at least one image of a first yarn defect associated with the cleaning limit is displayed from the database, the at least one image of the first yarn defect including yarn defects that are not eliminated by the cleaning limit, the cleaning limit is modified based upon an appraisal of the displayed at least one image of the first yarn defect, and the modified cleaning limit is stored and the defects cut out of the yarn using the modified cleaning limit.

Full Text

The invention relates to a process and a device for cleaning yarn, defects in the yarn being cut out and a cleaning limit separating defects which are to be cut out from defects which are not to be cut out. In devices of this type which are also called yarn cleaners, it is conventional to manually adjust a cleaning limit in that adjustment values are input in a control apparatus to establish a cleaning curve of- this type. This process is very complicated, because good cleaning limits can only be found by complicated trials. This means that, with a first cleaning limit, yarn is produced and the quality of the yarn and the products produced therefrom is then tested, whence data for the adjustment of a new improved cleaning limit has to be found. The cleaning limit which has been found must then also finally be adjusted in a plurality of control apparatuses on spinning frames. A process and a device of the above-mentioned type are known from EP 0 877 108 in which the cleaning limit is adjusted automatically. To this end, yarn defects are detected from a first yarn portion, in that values for the thickness and length of thickness variations of the yarn are measured and collected. With the aid of a computer, for example a so-called PC which contains a suitable programme, these values can be sorted and displayed in a graph, the values for the thickness and the associated values for the length of the defects being entered in a length/thickness graph. In this graph value ranges for various lengths of defects in the yarn are plotted along one axis and value ranges for the thickness of the defect in the yarn along another axis. Rectangular fields are thus produced which are limited by respective upper and lower limits for the length and upper and lower limits for the I now thickness of the defect. Defects detected in the yarn can be entered in the fields in this graph, so for each thickness and length range the number of detected defects is determined and the defect density in this range is obtained. Since with accurate measurements on the yarn even small deviations in the thickness from an average or from a predetermined value are detected, very many values and therefore also a very large defect density are obtained for these small deviations. These values can be allocated to a so-called "yarn package". They do not belong to real defects, as in practice they merely reflect the normal structure of Che yarn. Only deviations in the thickness which exceed a specific measure are noteworthy. In a first approximation, therefore, the defect density can be ascertained as a measure of the size or significance of the defect, namely as follows: The higher the defect density, the less disruptive is the corresponding defect. An optimum cleaning limit should accordingly combine points with identical defect density or identical defect size in one defect graph. Defects which lie on this cleaning limit are thus respectively equally disruptive. In this process, the operator inputs the number of cleaner cuts into the PC and thus obtains the optimum cleaning limit. If the operator agrees with Che curve obtained, he loads this into the memory of a control apparatus for the yarn cleaner which continues to work therewith. A disadvantage of this known process is that the cleaning limit is deCermined on the basis of values for an admissible number of cuts to the yarn. Therefore, the quality of the yarn and the subsequent products possibly needs to be checked and the cleaning limit then adapted again. The invention as characterised in the claims achieves the object of providing a process and a device which avoid these disadvantages and allow an improved, simplified and rapid adjustment of the cleaning limit, so the effect thereof in. the yarn can also be predicted more accurately. This is achieved in that the values, detected by the control apparatus of the yarn cleaner on each yarn defect, for the length, thickness and position along the yarn are evaluated in a new manner. By thickness we are here selectively referring to variables such as defect radius, defect cross-section or also defect mass. A graphic illustration of the cleaning limit is not necessary. Rather a set of simulated yarn defects is displayed in an image, -wherein the image, as described hereinafter can have various forms. In any case, the images always only shown defects which lie on the same cleaning limit. However, the defects can have varying form and length here. With reference to defects which lie on this cleaning limit and are displayed: the most disruptive defects in the yarn are those which still remain after cleaning the yarn, in other words are not removed by cleaning. Even slightly larger defects are, however, cut out. Simulated defect images are shown as defects in the images. Therefore, for each defect with a predetermined length and thickness, images or displays of the images have to be simulated and/or prestored. As a defect which is characterised by a pair of values for its length and thickness can have various forms in practice, it is even desirable to store a plurality of images or displays for a single defect to take possible variations of form into consideration. As a basis for the simulation, pattern tables are used which show yarn defects of defined length and thickness in these different variations of form. There are at least three possibilities for displaying the yarn defects. Firstly, individual yarn portions provided with defects can be shewn approximately in actual size. Secondly, small cut-outs from a sample fabric which contain yarn defects can be shown and, thirdly, larger fabric cut-outs can be shown where, in particular, the two-dimensional distribution of the defects in the fabric is recognisable. The device according to the invention therefore has yarn cleaners known per se which are connected to a spinning or winding frame and a computer (PC) which in its memory has displays of defects and a programme for classifying the defects. The computer also has means for displaying defect examples and contains prestored displays of defects or a programme for displaying defects from input data. It preferably also has selectable fields via which the calculation of a cleaning limit can be triggered. The advantages achieved by the invention are in particular that the adjustment of the cleaning limit is greatly simplified and therefore can be carried out even by relatively modestly qualified operators. The effect of the adjustment made can also be recognised very accurately. In particular, however, the cleaning limit can be influenced and determined by the desired quality of an end product. This quality which, for example, is expressed in the more or less even texture of the surface of a woven or knitted fabric can be considered directly when the cleaning limit for the yarn is determined. The display of the defects can emphasise both the type of defects or the effect of the distribution of the defects in the end product. The invention will be described in more detail hereinafter with the aid of an example and with reference to the accompanying drawings, in which: Fig. 1 is a schematic view of the device according to the invention, Fig, 2 to 7 each show defects in the display field. Fig. S is a view of a display on a PC screen. Fig. 1 shows a test piece moved longitudinally, here a yarn 1 wnich passes through a measuring gap 2 of a yarn cleaner 3. The yarn, cleaner 3 is connected via a line 4 to an evaluation unit 5 which in turn is connected via a bus 6 to a control apparatus 7, Further evaluation units and therefore further yarn cleaners can be connected via a further bus a to the control apparatus 7. The control apparatus 7 is connected via a bus or a network 7, such as, for example, Ethernet (LAN) etc. to a computer 10 which can, for example, be a conventional PC with display means. The PC thus also has the known elements such as screen 11, input keyboard 12 and processor 13. Various programmes are stored in the computer 10, for example a programme for fabric simulation, a programme for establishing a first cleaning limit and a programme for producing defect images and storing predetermined defect images. A programme for simulating fabric is commercially available under the name USTER EXPERT and described in principle in US 5,671,061, A programme for establishing a cleaning limit is sold by the company ZELLWEGER USTER under the name CAY and is known in principle from _EP 0 877 108. Typical defect images in the yarn are known from the classification system USTER CLASSIMAT and shown, for example, in the document "USTER News Bulletin" Ho. 29, August 1981 on pages 4, 6 and 15. Fig. 2 shows an example of defects in an end product such as yarn which could be on the same cleaning limit and therefore are undesired or tolerated to the same degree and therefore can be allocated to points of a cleaning limit. The defect 14 is called a short thick point, the defect 17 a long thick point which, however, has a smaller thickness. The defects 15 and 16 are somewhere inbetween in their measurements. Fig. 3 shows similar defects to Fig. 2 which, however, have a smaller thickness in total and therefore should be less disruptive. This display emphasises the tvce of dpfpf-f-e Fig. 4 shows the same defects 14 to 17 as Fig. 2 but in a cut¬out from a fabric. Fig. 5 shows the same defects 18 to 21 as Fig. 3 but in an environment. Fig. 6 shows a web 25 of a woven or knitted fabric, in which yarn defects are denoted by reference numerals 26 to 29. Fig. 7 shows a web 3 0 of a woven or knitted fabric, in which yarn defects are denoted by reference numerals 31 and 32. This view emphasises the distribution of the defects in the end product. Fig. 8 shows the view as it can be constructed on a screen. 33 denotes a web of an end product such as a woven or knitted fabric which has visible yarn defects, as denoted, for example, by 34, 35 and 35. In a field 37 to the right thereof, these yarn defects are enlarged and shown at the same level, so the nature thereof can be recognised. Five different variations are shown in field 38 for one and the same defect. Ail these variations are classified in the same field as they are felt to be equally disruptive, although their shapes differ from one another. Field 39 and 40 can be selected, for example by a mouse. Selection of field 3 9 restricts the cleaning limit and selection of field 40 makes it more tolerant. The operating method of the invention is as follows: Prior to or at the beginning of yarn production or for a specific production lot, a cleaning limit is input. This can take place, for example, in the manner known from EP 0 877 10 3. In any case, this cleaning limit must finally be prestored in the computer 10 or be determined by a suitable programme. Yarn defects, for example, which can be allocated to this cleaning limit as shown next to one another or in succession in one of Fig. 2, 4 or 6 are -hen shown on the screen 11 in the end product, i.e. in the yarn 1, in the woven or knitted fabric 25, 30. The operator can choose between, for example, three displays as shown in Fig. 2, 4 and 6 and can now judge whether or not he can allow the shown defects in the yarn. If he cannot allow them, he has, perhaps, adjusted his cleaning limit too insensitively. He can restrict it in that he makes a corresponding input on the input keyboard 12 or selects the field 3 9 (Fig. 81 on the screen 11 via a mouse. The processor 13 then calculates a new cleaning limit which cuts out more defects and new images of defects appear on the screen 11 as shown, for example, by Fig. 3, 5 and 7. Conversely, the cleaning limit can also be adjusted more tolerantly, for example in that the field 40 is selected. As a check, the number of expected cleaner cuts for each cleaning limit can be displayed in one display field. As soon as the simulation of the defects allows the desired quality features to be recognised, securing of the cleaning limit and downloading into the control apparatus 1 take place to trigger the cleaner 3. The production of yarn can now be taken up with the optimised cleaning limit. As described above, images of yarn defects can be stored in the computer 10. These images can correspond to real depictions like photographs which to this end are digitalised and stored. As the number of images input in this way is limited, further images, which show yarn defects which are not prestored because they have differences which are too small from the prestored images, can be produced from two images by interpolation with known image processing algorithms. WE CLAIM : 1. A method for cleaning yarn by cutting out defects in the yarn using a cleaning limit for separating defects which are to be cut out from defects which are not to be cut out. wherein a cleaning limit for eliminating at least one defect in a yarn according to its length and thickness is selected, a database of yarn defect images is established and at least one image of a first yarn defect associated with the cleaning limit is displayed from the database, the said one image of the first yarn defect including yarn defects (14-21, 26-29, 31, 32) that are not eliminated by the cleaning limit, the cleaning limit is modified based upon an appraisal of the displayed at least one image of the first yarn defect, and the modified cleaning limit is stored and the defects cut out of the yarn using the modified cleaning limit. 2. The process as claimed in claim 1, wherein the defects displayed are the most disruptive defects which still remain in the end product after cleaning. 3. The process as claimed in claim 1, wherein defects in a yarn are shown as a display. 4. The process as claimed in claim 1, wherein defects in a fabric are shown as a display. 5. The process as claimed in claim 4, wherein the display emphasises the type of defects. 6. The process as claimed in claim 5, wherein the display emphasises the effect of the distribution of the defects in the end product. 7. A device for cleaning yarn by cutting out defects in the yarn using a cleaning limit for separating defects which are to be cut out from defects which are not to be cut out, comprising a yarn cleaner (3), a computer (10), connected to the yarn cleaner, configured to execute, starting from a cleaning limit, the step of retrieving and displaying prestored displays of defects in an end product that make an effect of the defects in the end product visible, and a means connected to the computer for displaying examples of defects. 8. Device as claimed in claim 7, wherein the computer uses prestored displays of defects. 9. The device as claimed in claim 7, wherein the computer has a programme for producing defect images. 10. The device as claimed in claim 7, wherein fields (39, 40) which is capable of being selected thereon are provided, by means of which the calculation of a cleaning limit is capable of being triggered.

Documents:

in-pct-2001-1607-che abstract-duplicate.pdf

in-pct-2001-1607-che abstract.pdf

in-pct-2001-1607-che assignment.pdf

in-pct-2001-1607-che claims-duplicate.pdf

in-pct-2001-1607-che claims.pdf

in-pct-2001-1607-che correspondnece-others.pdf

in-pct-2001-1607-che correspondnece-po.pdf

in-pct-2001-1607-che description(complete)-duplicate.pdf

in-pct-2001-1607-che description(complete).pdf

in-pct-2001-1607-che drawings-duplicate.pdf

in-pct-2001-1607-che drawings.pdf

in-pct-2001-1607-che form-1.pdf

in-pct-2001-1607-che form-19.pdf

in-pct-2001-1607-che form-26.pdf

in-pct-2001-1607-che form-3.pdf

in-pct-2001-1607-che form-5.pdf

in-pct-2001-1607-che form-6.pdf

in-pct-2001-1607-che pct.pdf

in-pct-2001-1607-che petition.pdf