ASTM D1422-1999(2008) Standard Test Method for Twist in Single Spun Yarns by the Untwist-Retwist Method《退捻加捻法测定单细纱捻数的标准试验方法》.pdf
《ASTM D1422-1999(2008) Standard Test Method for Twist in Single Spun Yarns by the Untwist-Retwist Method《退捻加捻法测定单细纱捻数的标准试验方法》.pdf》由会员分享,可在线阅读,更多相关《ASTM D1422-1999(2008) Standard Test Method for Twist in Single Spun Yarns by the Untwist-Retwist Method《退捻加捻法测定单细纱捻数的标准试验方法》.pdf(5页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D 1422 99 (Reapproved 2008)Standard Test Method forTwist in Single Spun Yarns by the Untwist-Retwist Method1This standard is issued under the fixed designation D 1422; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method2describes the determination of twist insingle spun yarns when only an approximation of the
3、true twistis required.NOTE 1For a more accurate method see Test Method D 1423.1.2 This test method is applicable to spun single yarns incontinuous lengths, and also to spun yarns raveled fromfabrics, provided specimens at least 200 mm (8 in.) long can beobtained.1.3 The values stated in either inch-
4、pound or SI units are tobe regarded separately as standard. Within the text, the SI unitsare shown in parentheses. The values stated in each system arenot exact equivalents; therefore each system shall be usedindependently of the other. Combining values from the twosystems may result in nonconforman
5、ce within this test method.1.4 This test method has been found satisfactory for use indetermining twist in all single ring spun yarns and 100% cottonopen-end yarns. For all open-end spun yarns that are not 100 %cotton this test method has not been found to be satisfactory fordetermining twist but ma
6、y be used to measure deviation froman average value.1.5 This specification shows the values in both inch-poundunits and SI units. The “inch-pound” units is the technicallycorrect name for the customary units used in the United States.The “SI” units is the technically corrected name for the systemof
7、metric units known as the International System of Units. Thevalues stated in either acceptable metric units or in other unitsshall be regarded separately as standard. The values expressedin each system may not be exact equivalents; therefore, eachsystem must be used independently of the other, witho
8、utcombining in any way.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of this standard to establish appropriate safetyand health practices and determine the applicability of regu-latory limitations prior to use.2. Ref
9、erenced Documents2.1 ASTM Standards:3D 123 Terminology Relating to TextilesD 1059 Test Method for Yarn Number Based on Short-Length SpecimensD 1423 Test Method for Twist in Yarns by Direct-Counting3. Terminology3.1 Definitions:3.1.1 direction of twist, nthe right or left direction of thehelix formed
10、 in a twisted strand as indicated by superimposi-tion of the capital letter “S” or “Z.”3.1.1.1 DiscussionYarn has S twist if, when the yarn isheld in a vertical position, the visible spirals or helices aroundits central axis conform in direction of slope to the centralportion of the letter“ S,” and
11、Z twist if the visible spirals orhelices conform in direction of slope to the central portion ofthe letter “Z.” When two or more yarns, either single or plied,are twisted together, the letters “S” and “Z” are used in asimilar manner to indicate the direction of the last twistinserted.3.1.2 single ya
12、rn, nthe simplest strand of textile materialsuitable for operations such as weaving, knitting, etc.3.1.2.1 DiscussionA single yarn may be formed fromfibers with more or less twist; from filaments with or withouttwist; from narrow strips of materials such as paper, cello-phane, or metal foil; or from
13、 monofilaments. A yarn which iseither twistless or can be rendered twistless in a singleuntwisting operation. When twist is present, it is usually all inthe same direction.3.1.3 spun yarn, nin a staple system, a continuous strandof fibers held together by some binding mechanism.3.1.3.1 DiscussionThe
14、 binding mechanism most com-monly used in spun yarns is twist. Other useful mechanisms1This test method is under the jurisdiction of ASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.58 on Yarns and Fibers.Current edition approved Aug. 1, 2008. Published October 2008
15、. Originallyapproved in 1956. Last previous edition approved in 1999 as D 1422 99.2This test method is commonly designated by the less precise term“ Untwist-Twist Method.”3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Ann
16、ual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.that are used are chemical additives, wrapping, entanglement,or some combin
17、ation of these. Test Method D 1422 is appli-cable only to yarns which have twist.3.1.4 twist, nin textile strands, the helical or spiral con-figurations induced by turning a strand about its longitudinalaxis.3.1.4.1 DiscussionTwist is usually expressed as the num-ber of turns about the axis that are
18、 observed in a specifiedlength either metres (tpm) or inches (tpi).3.1.5 twist factor, TF, nthe product obtained when thetwist expressed in turns per centimetre is multiplied by thesquare root of the yarn number expressed in tex:Twist factor TF!5tpcm 3 =T (1)where:T = yarn number expressed in tex.3.
19、1.5.1 DiscussionTwist multiplier and twist factor are ameasure of the “twist hardness” of yarn because they areapproximately proportional to the tangent of the angle betweenfibers on the outer yarn surface and the axis of the yarn; thelarger this angle, the harder the twist. Furthermore, this anglei
20、s a function of both the twist content (turns per unit length)and the number of fibers per yarn cross section (yarn number).Hence, twist content alone cannot provide a measure of thetwist hardness of a yarn. Twist multiplier and twist factor areproportional to each other and differ only in the units
21、 used.The two are related by Eq 2 and Eq 3:TF 5 k 3 TM (2)k 5 277.29/=L (3)where:L = length in yards of the hank used to define the indirectyarn number of the type,N = hanks/lb. In particular for cotton count,k = 9.567 so that Eq 2 becomes Eq 4:TF 5 9.567 3 TM (4)3.1.6 twist multiplier, TM, nthe quo
22、tient of the twistexpressed in turns per inch and the square root of the yarnnumber in an indirect system.Twist multiplier TM!5tpi/ =N (5)where:N = yarn number in an indirect system, the cotton systemunless otherwise specified.3.1.7 yarn, na generic term for a continuous strand oftextile fibers, fil
23、aments, or material in a form suitable forknitting, weaving, or otherwise intertwining to form a textilefabric.3.2 For definitions of other textile terms used in this testmethod, refer to Terminology D 123.4. Summary of Test Method4.1 A specimen is untwisted and then retwisted in theopposite directi
24、on until it contracts to its original length. It isassumed that the same amount of twist has been inserted as wasoriginally present. Twist, as turns per unit length, is calculatedas half the number of turns registered on the counter divided bythe specimen length.5. Significance and Use5.1 This test
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