BS ISO 16549-2005 Textiles - Unevenness of textile strands - Capacitance method《纺织材料 纤维绳的不匀性 容量法》.pdf

1、BRITISH STANDARD BS ISO 16549:2004 Textiles Unevenness of textile strands Capacitance method ICS 59.060.01 BS ISO 16549:2004 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 9 February 2005 BSI 9 February 2005 ISBN 0 580 45397 9 National forew

2、ord This British Standard reproduces verbatim ISO 16549:2004 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee TCI/24, Textiles Physical testing, which has the responsibility to: A list of organizations represented on this com

3、mittee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” fac

4、ility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligatio

5、ns. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pa

6、ges This document comprises a front cover, an inside front cover, the ISO title page, pages ii to v, a blank page, pages 1 to 10, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publicatio

7、n Amd. No. Date CommentsINTERNATIONAL STANDARD ISO 16549 First edition 2004-06-01 Reference number ISO 16549:2004(E) Textiles Unevenness of textile strands Capacitance method Textiles Irrgularit des fils textiles Mthode capacitiveBSISO16549:2004ii id FDPscalimer ThFDP si fam eliy ctnome niat deddeby

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12、tela 65 -HCG 1121eneva 02 T.le 22 14 + 10 947 11 Fxa + 22 14 0 94774 9 Eam-il ocpyrithgios.ogr Web wwwi.soo.rg Pbuni dehsil Stiwrezldna BSISO16549:2004 iii Contents Page 1 Scope 1 2 Normative references 1 3 Terms and definitions 1 4 Principle 2 5 Apparatus . 3 6 Atmosphere for conditioning and testi

13、ng . 4 7 Sampling . 4 8 Procedure . 5 9 Calculations and expression of results . 6 10 Test report 6 Annex A (informative) Other methods for the determination of unevenness . 8 Bibliography . 10 BSISO16549:2004iv Foreword ISO (the International Organization for Standardization) is a worldwide federat

14、ion of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committe

15、e. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance

16、with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires app

17、roval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 16549 was prepared by Technical Commi

18、ttee ISO/TC 38, Te x t i l e s, Subcommittee SC 23, Fibres and yarns. This International Standard cancels and replaces ISO 2649 which is now obsolete. BSISO16549:2004 v Introduction In the 1960s the International Wool Textile Organization (IWTO) prepared an unevenness method destined for yarns and o

19、ther strands made of wool. The method was adopted by ISO as ISO 2649:1974. It contains a discussion of the principles of unevenness testing and refers to the then-popular unevenness tester, the 1960s model of the Uster Evenness Tester, which was obsolete in mid-2000 when the present International St

20、andard was written. Later, the IWTO prepared a new method, IWTO-18-00, published in 2000. ISO 16549 has mostly new wording but includes some elements of ISO 2649 and of IWTO-18-00 with thanks to IWTO. BSISO16549:2004. iv ANRETNIITOTS LANDNADRA ISO 45614002:9)E(1 Textiles Unevenness of textile strand

21、s Capacitance method 1S c o p e This International Standard describes a method, using capacitance measuring equipment, for determining the unevenness of linear density along the length of textile strands. The method is applicable to tops, slivers, rovings, spun yarns and continuous filament yarns, m

22、ade from either natural or man-made fibres, in the range of 4 tex ( ) to 80 ktex ( ) for staple-fibre strands and 1 tex ( ) to 600 tex ( ) for continuous-filament yarns. It is not applicable to fancy yarns or to strands composed fully or partly of conductive materials such as metals; the latter requ

23、ire an optical sensor (see A.4). The method describes the preparation of a variance-length curve, as well as the determination of periodicities of linear density. It covers also the counting of imperfections in the yarn, namely of neps and of thick and thin places. Irregularities in the distribution

24、 of additives such as sizes, in moisture content and in fibre blending may increase the measured unevenness above its true value. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. Fo

25、r undated references, the latest edition of the referenced document (including any amendments) applies. ISO 139, Te x t i l e s Standard atmospheres for conditioning and testing 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 unevenness varia

26、tion of linear density along the length of a continuous strand or yarn NOTE The term is also used occasionally for the variation of yarn diameter. 3.2 coefficient-of-variation unevenness value of unevenness (3.1) expressed as a coefficient of variation NOTE 1 The coefficient-of-variation unevenness

27、is expressed in percent, for example . NOTE 2 See also 4.5 and 4.6. 3.3 mean-deviation unevenness value of unevenness (3.1) expressed as an average mean deviation NOTE 1 The mean-deviation unevenness is expressed in percent, for example, . g/km kg/km g/km g/km CV u CV u = 18,3 % U u U u = 14,6 % BSI

28、SO16549:20042 NOTE 2 See also 4.5 and 4.6. 3.4 capacitor length effective length of the capacitor in the direction of the specimen movement, usually to 3.5 length between length of the test specimen for which the instrument takes an individual reading of mass NOTE 1 The unevenness value decreases as

29、 is increased. NOTE 2 In the capacitance method, is normally the capacitor length but it can be increased electronically. NOTE 3 is sometimes referred to in the literature as . 3.6 length within length of the specimen for which an individual value of unevenness is determined and a reading is given N

30、OTE 1 The unevenness value increases as is increased. When is more than or so, then a further lengthening of increases (or ) only slightly. NOTE 2 is sometimes referred to in the literature as . 3.7 total measured length sum of all measured lengths 3.8 nep tightly tangled knot-like mass of unorganiz

31、ed fibres 3.9 package yarn wound to a shape, which may be supported (for example, bobbins, cones) or unsupported (for example, skeins, cakes), suitable for conditioning and testing 3.10 spectrogram attachment to unevenness testers for the calculation and presentation of periodic variations in the st

32、rand 3.11 thick place yarn defect with linear density substantially (at least ) greater than that of the adjoining segments of the yarn and extending for at least 3.12 thin place yarn defect with linear density substantially (at least ) smaller than that of the adjoining segments of the yarn and ext

33、ending for at least 4P r i n c i p l e 4.1 A specimen is passed between two plates of a capacitor causing changes in capacitance which are proportional to the changes of mass of the specimen. The instrument evaluates these changes and reports them as or . 8mm 20mm L b L b L b L b B L w L w L w 100 m

34、 L w CV u U u L w W L w 50 % 5mm 50 % 5mm CV u U u BSISO16549:2004 3 4.2 The fibre dielectric constant is also a factor determining the capacitance change. As long as the dielectric constant is unchanging (non-blended strands or perfectly uniform blending), the dielectric constant has no influence o

35、n the unevenness reading, which depends solely on the variation of mass. If the dielectric constant differs for the types of fibres in a blend and if, at the same time, the blend is irregular, then the reading of unevenness is increased above its true value. The interpretation of results therefore r

36、equires caution. 4.3 Several studies have been conducted over the years, see Reference 3 for example, comparing the true unevenness of a specimen, determined by cutting and weighing (see A.3.1), with the reading from an unevenness tester. Good agreement was obtained, so the readings from the tester

37、can be taken as being the true unevenness value. 4.4 The value of unevenness has meaning only if both and are known and they should, in principle, always be reported, preferably as ( , ). EXAMPLE ( , ). In practice, these two values are usually left unstated and are assumed to be those of the most c

38、ommonly used unevenness tester, namely : for yarns, for rovings, for slivers and tops; : total length of yarn on the package. 4.5 There are two possible expressions for unevenness, and . The is now obsolete and its use, while permitted, is discouraged. is the preferred expression. 4.6 If mass is dis

39、tributed near to “normal”, then the ratio of is approximately 1,25. This conversion factor must be used cautiously because, in case of departures from normality, the ratio can be considerably different. The conversion factor may be used to convert a table of quality levels from to . 4.7 When is plot

40、ted against , a “variance-length curve” is obtained which gives additional information on the materials unevenness. When the plot is made on log-log paper, then the curve is almost a straight line and its slope gives information on the relationship between short-term and long-term unevenness. 4.8 Un

41、evenness testers usually contain a spectrogram, which analyses the data and provides information on periodic variations of linear density. This information is useful in finding faults in the processing. The analysis uses an algorithm based on the Fourier transformation. 4.9 Unevenness testers usuall

42、y contain a counter for yarn imperfections, namely neps, and thick and thin places. The level beyond which the imperfections are counted can be adjusted. 4.10 Unevenness is a fundamental feature of yarn construction. It influences the efficiency of processing as well as fabric appearance. Lower unev

43、enness generally results in a better-looking fabric but the relation is not simple and interpretation requires special care. 5 Apparatus 5.1 Different types of apparatus are in use for measuring strands made of staple fibres and filament yarns. 5.2 The apparatus consists of the following elements: a

44、) measuring device, featuring several measuring condensers, usually grouped into one unit, for strands of varying linear density, yarn guiding and pretensioning devices, an adjustable-speed motor to advance the strand; L b L w CV u L b L w CV u 10 mm 1 000 m L b 8mm 12mm 20mm L w CV u U u U u CV u C

45、V u /U u U u CV u CV u L b BSISO16549:20044 b) signal processing unit, which computes and indicates the values of or and may also calculate the variance-length curve and present a graph of the periodic variations of linear density, also counts the number of imperfections in most instruments. The uni

46、t shall be able to operate at the threshold level of , above which thick places are counted, and the level of , below which thin places are counted. reports a reading for neps which shall be a product of the length, expressed in millimetres, of the nep and the percent excess over the average linear

47、density of the yarn (for example, ). The level of , above which neps are counted, shall be available. other levels (for the three imperfection types) are also usually available; c) printer (optional), which provides a plot of the linear density of the strand; d) twisting device for testing untwisted

48、 or low-twist filament yarns. This device produces false twist in an untwisted or low-twist filament yarn, so that the yarn presents a nearly round cross-section as it passes through the condenser. If the yarn passes through in a flat mode, there is the danger of adding variation depending on the wa

49、y the flat yarn is presented. The direction of the imparted false twist must be the same as that of any twist present in the yarn. The twisting device need not be used for the testing of monofilaments. 5.3 To calibrate, use the procedure built into the instrument if possible. Alternatively, use a standard (usually tape) of known unevenness provided by the instrument manufacturer and follow the manufacturers instructions. Finally