CGSB 4 2 NO 73 2-M91-CAN CGSB-1991 Methodes Pour Epreuves Textiles Laine - Determination Des Parametres De Distribution De Longueur Des Fibres - Methode Electronique ISO 2648 1974《.pdf

1、CGSB CAN/CGSB-4.2 N0.73-2-tI91 * = 18746.50 0011888 989 NATIONAL STANDARD OF CANADA CAN/CGSB-4.2 NO. 73.2-M91/ IS0 2648:1974 Textile Test Methods Wool - Determination of Fibre Length Distribution Parameters - Electronic Method Prepared by the International Organization for Standardization Reviewed b

2、y the I Canadian General Standards Board Copyright Canadian General Standards Board Provided by IHS under license with CGSBNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-CGSB CAN/CGSB-4-2 NO-73-E!-MqL ti = 1874650 0013887 815 The CANADIAN GENERAL STANDARDS BOARD (

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19、da KIA 1G6 in Person - Place du Portage III, 9Cl 11 Laurier Street Hull, Quebec I Copyright Canadian General Standards Board Provided by IHS under license with CGSBNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-CGSB CAN/CGSB-4=2 N0.73.2-NqL *.- LA74650 OOLLA90 537

20、 M NATIONAL STANDARD OF CANADA C ANICGSB-4.2 NO. 73.2-M91/ IS0 2648:1974 TEXTILE TEST METHODS WOOL - DETERMINATION OF FIBRE LENGTH DISTRIBUTION PARAMETERS - ELECTRONIC METHOD Prepared by the International Organization for Standardization Reviewed by the Canadian General Standards Board ea Approved b

21、y the Standards Council of Canada miblished June 1991 by the Canadian General Standards Board Ottawa, Canada K1A 1G6 Minister of Supply and Services Canada - 1991 No part of this publication may be reproduced in any form without the prior permission of the publisher. Copyright Canadian General Stand

22、ards Board Provided by IHS under license with CGSBNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-CGSB CAN/CGSB-4.2 N0-73*2-M91 * H 1874650 OOLL91 V73 E 7 , CANADIAN GENERAL STANDARDS BOARD COMMITTEE ON TEXTILE TEST METHODS (Membership at date of approval) Crown, D

23、r. E.M. Chairperson Biron, C. Clarke, Mrs. N. Cosman, Ms. V. Demen, A. Doihan, Mrs. P. Duhamel, Ms. D. Edwards, D.S. Farnworth, Dr. B. Graham, M. Grgoire, Miss M. Hurley, Ms. M. Kasem, Dr. M.A. King, Dr. M. Kiimes, A. Mitton, Miss M.T. Monk, W.B. Mortimer, R.A. Muni it may be used on top sliver, on

24、worsted drawing slivers and rovings, and on slivers from the semi-worsted system. 2 PRINCIPLE AND DEFINITION OF THE TEST PARAMETERS 2.1 Principle The electronic machine tests the length of textile fibres, using a specimen of fibres made up with the aid of the mechanical grip. This grip, fed with sli

25、vers or rovings, prepares a numerical specimen of fibres, .e. one in which the number of fibres in each length class are represented in the same proportion as in the original sliver. This specimen is in the form of a draw of parallel fibres, all these fibres having their ends approximately on a line

26、 perpendicular to the direction of the fibres. The specimen formed in this way is then transferred from the grip to an electronic instrument, where it is placed in a slide between two thin plastic sheets. lhe slide containing the test specimen moves at constant speed, through a measuring condenser.

27、The variation in capacity caused in this way (due to the partial replacement of the “air“ dielectric by the “wool“ dielectric) is proportional to the mass of the portion of the draw of fibres situated in the condenser. In view of the constitution of the specimen, it is easily shown that the record o

28、f changes in the signal proportional to the changes in capacity is equivalent to a diagram of “hauteur“ H (see references 1 and 2, annex A). This diagram is automatically traced by a recorder connected to the main machine. 2.2 Test parameters An electronic calculator that is incorporated automatical

29、ly evaluates the following length distribution parameters during test : i) mean cross-section biased length or hauteur H : (a, I) in Palmers notation; 2) coefficient of variation of hauteur, CVH; 3) mean length X cross-section biased length, or barbe B: (al, I) in Palmers notation. As the density of

30、 the fibres may be regarded as constant, the barbe B is also the mean weight biased : (w, /I in Palmers notation. 3 APPARATUS The apparatus comprises three parts : i) the mechanical grip; 2) the main electronic instrument; 3) the recorder. A suitable machine is described in annex C. 3.1 The mechanic

31、al grip The grip works in the same way as the nip of a rectilinear comb. With each movement it extracts from the sliver a numerical sample containing all the fibres having their ends within a short length of the sliver, between two cross-sections perpendicular to the sliver axis about 2.5 to 3.7 mm

32、apart. The complete specimen is made up of a collection of about ten to sixteen of these samples. 3.2 Tha min dectronic instrument The main electronic instrument consists of two parts : i) a device for measuring the local mass of the fibre specimen, and 2) a calculator, automatically evaluating the

33、length distribution parameters during the test. NO. 73.2-M91 1 Copyright Canadian General Standards Board Provided by IHS under license with CGSBNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 NO. 73.2-M91 i CGSB CAN/CGSB-4*2 N0*73-2-M9L * = 1874650 0011874 182 I

34、S0 2648-1974 (E) 3.3 The recorder A galvanometric or potentiometric recorder automatically traces the cumulative diagram of hauteur on squared paper during the test (see figure 1). The diagram ordinate gives the percentage (linear density biased) of fibres, the length of which is greater than the le

35、ngth shown by the corresponding abscissa. (The linear . density biased percentage is very near to the numerical percentage.) The lengths in abscissa are actual lengths (scale 1/1). 4 TEST SPECIMENS 4.1 In the case of wool top slivers, the mass of which is between 15 and 30g/m, a length of 1.20m of s

36、liver is broken off from the ball or bump top. Immediately after drawing this sample, it is held under slight tension and given 24 turns of twist; held taut in this state, it is then gripped at its centre, the two ends placed together and held there. It then suffices to release the centre progressiv

37、ely, turn by turn, keeping it slightly tensioned, to form a very uniform compact hank. In this form, the sample may be kept indefinitely; it may easily be sent by post in a plastic bag to the testing laboratory. This twisting operation is absolutely essential in order to obtain accurate rest results

38、 5 CONDITIONING ANO TESTING ATMOSPHERE Under normal conditions, the electronic testing instrument is affected neither by the moisture content of the sliver nor by the temperature and humidity of the room where the test takes place. However, the preparation of the specimen by the mechanical grip and

39、the operations of transferring the specimen from the mechanical grip to the Almeter are much more easily performed with a sliver having a sufficiently high moisture content, corresponding to its regain in an atmosphere of between 55 and 75 96 relative humidity. (In this way difficulties due to stati

40、c electricity are avoided.) Furthermore, the test is sensitive to sudden large variations in the local moisture content along the sliver, such as for example from the application of fibre lubricants in drop form followed almost immediately by testing. Also, slivers that have undergone treatment invo

41、lving soaking (dyeing, backwashing, etc.) and those coming from a dryer should only be tested after a delay sufficient for moisture content variations to come to equilibrium. In the case of samples of which the moisture content and particularly its homogeneity along the sliver are unknown, it is thu

42、s preferable to carry out a preliminary conditioning, The instructions that follow are based on these considerations. 5.1 Conditioning atmosphere The twisting operation may be omitted only in the case when the ball of sliver or roving is available at the time of testing, or when the test is carried

43、out within 4 h of sampling. It is, however, preferable in all cases to work according to the instructions above. 4.2 In the case of rovings or drawing slivers with a mass less than 15 g/m, a sufficient number of successive samples of 1.20 m are broken off to constitute, by juxtaposition, a sliver wh

44、ose mass per metre is about 22 g (30 g maximum). In the juxtaposition, the slivers are always placed in the same direction (for example the leading end always to the left). Then, without delay, this made-up sliver is subjected to the twisting and hanking operation described in 4.1. 4.3 Samples must

45、not be drawn from the outer layer (generally damaged by handling), nor from too near the centre of the ball. 4.4 Slivers having adventitious thickness faults (especially abnormal thick or thin placed are to be discarded. Also, slivers coming directly from the comb, “cut“ or “chopped“ slivers, and th

46、ose containing fibre bundles (sometimes only apparent by examination of the sliver against the light) cannot be used in the test. In all these cases, the variation in fibre length between successive specimens is very great and very large errors may result. 5.1.1 Test in a testing laboratory The samp

47、le, kept in the form of a twisted hank, is exposed to the conditioning atmosphere for a minimum period as indicated below. This period may possibly vary according to the type of material and the sampling conditions. Generally, regardless of the origin of the sample of sliver, the preliminary conditi

48、oning period is 24 h in the standard atmosphere for testing as defined in IS0 139. 5.1.1.1 In the most frequent case of tops sampled in the normal way at a passage following combing, and all drawing slivers and rovings sampled from a machine where fibre lubricant is not applied, the period of condit

49、ioning in standard atmosphere can be reduced to a minimum of 4 h. In some circumstances this period can be reduced still further - for instance, if a rapid conditioning enclosure is available in which the sample hank can be placed for half an hour followed by a further half hour in the standard atmosphere. Finally, the conditioning period may be omitted or reduced to a precautionary half hour when a combination of the following conditions occurs : a) Sampling has taken place recently (approximately wi