YARN PROPERTIES MEASUREMENT: AN OPTICAL APPROACH

Transcription

1 nd INTERNATIONAL TEXTILE, CLOTHING & ESIGN CONFERENCE Magic Wold of Textiles Octobe 03 d to 06 th 004, UBROVNIK, CROATIA YARN PROPERTIES MEASUREMENT: AN OPTICAL APPROACH Jana VOBOROVA; Ashish GARG; Bohuslav NECKAR & Sayed IBRAHIM Abstact: Yan popeties including, effective diamete, and haiiness ae measued optically. A study has been done to measue effect of yan twist and fineness on haiiness. An attempt has also been made to evaluate CV%(mass) at vey shot cut-lengths, which can be of geat inteest while investigating CV% of yan stength, because uptue zone of yan anges fom 1- mm. Results ae in close ageement with USTER evaluation. Expeimental esults of yan diamete ae compaed with theoetical values obtained fom Pof. Necka s Compession theoy. Keywods: Yan diamete, Haiiness, Optical measuement, CV% at small lengths 1. Intoduction Conventionally, capacitive method is used to measue mass distibution along the length of the yan. Capacitance of homogenous dielectics in a unifom electic field is geneally popotional to mass, but is also a function of fequency and fo cotton, additional substances (e.g., moistue) and iegula geomety may affect capacitive measuement esults [1]. Some moden instuments use optical methods fo diect measuement of yan diamete and haiiness. The optical chaacteistics of cotton ae a combination of light absoption (elated to density) and scatteing, with density and scatteing esults vaying as a function of wavelength, paticula contents in the fibe (e.g., moistue), and fibe geomety [1]. In the pesent wok, an optical method is poposed to measue conventional paametes of yan. In addition, with the poposed methodology many othe featues of yan can be highlighted. Most impotant being haiiness in the yan [], and CV% ae nea zeo lengths. CV% at zeo length can be of geat inteested in investigating vaiation in yan stength because uptue zone of yan anges fom 1- mm [3]. Effect of twist on haiiness has been investigated.. Haiiness Theoy by Pof. Necka Thee exists diffeent shapes of fibes in the sphee of haiiness between two adii and, such as fibe end (1), loop (), potuding fibe (3), evesal end (4), and evesal loop (5) (Figue 1). The occuence of the evesal shapes (4) and (5) is so small in yan that these can be neglect. Imaginatively, the loop () can be cut so as to obtain a couple of fibe ends (a, b). Based on this idea, the fibe segments (we call these shotly as fibes ) potuding fom the yan body ceate the sphee of haiiness. It is evident fom Figue that the numbe of fibes potuding fom the cylindical shape of yan compact body (diamete, adius = ) is maximum and the numbe of fibes potuding fom the adius =/ Figue : Potuding fibes > is smalle, because the fee end of some of the fibes ae teminated between these two adii a b Figue 1: Fibe types The diffeential pobability ϕ ( )d, that a andomly chosen fibe suely potuding fom the adius having its fee end lying in the diffeential laye following immediately afte the adius (Figue 3) is geneally a function of the adius. But we assume that this pobability is independent of the adius ( ϕ = ). Futhe we assume the chaacte of fibe oientation is ( ) const. independent of the adius too. Based on these assumptions, we deived the following elation of packing density µ at any adius of the haiiness sphee. µ= µ ( ) ( ) h (1) 1

2 Hee nd INTERNATIONAL TEXTILE, CLOTHING & ESIGN CONFERENCE Magic Wold of Textiles Octobe 03 d to 06 th 004, UBROVNIK, CROATIA µ is the initial packing density coesponding to yan adius and h is the half-decease inteval of the numbe of potuding fibes. (It means always one half of the fibes that ae potuding fom the cylindical aea of adius will also potude fom the same of adius + h.) =/ Some of the paallel light beams can pass beside the x yan at a distance x, but othes ae hindeed by hais y-axis (Figue 4). Figue 4: Light beams It is evident fom Figue 5 that the light beam can pass though the gay stip of width if none of the fibe centes is lying exactly at the middle of the stip. (Hee we idealize each fibe coss section by a ing of diamete.) Based on this idea, the pobability P that the light beam passes beside the yan at the distance x without any obstuction is yan axis x light beam x-axis d Figue 3: Fee fibe end d * Idealized fibe sections x d * Figue 5: Hindeing of the light beam by yan coss-sections π ( ) ( ) x d hcos π ( ) ( cos ) h α x+ d h α ln P= 8 h ( d ln ) d d µ π α α 0 0. () We call the model accoding to equations (1) and () as an exponential model of haiiness. But, the expeimental esults showed that this model is not enough pecise. It is necessay to thing about types (subscipt 1 o ) of fibes in the sphee of haiiness. Each of them follows the exponential model mentioned befoe, but with highly diffeent values of paametes h, h and µ, 1 µ. Then the packing density in this double-exponential model is ( ) h1 ( ) h µ= ( ) µ 1 +µ, (3) and the pobability P that the light beam passes beside the yan at the distance x is π ( ) ( ) x d h cos π ( ) ( cos ) h i α x+ d h i i α ln P= 8 ( d ln ) i hi d d π µ α α 0 0 i= 1 Z x that the light beam cannot pass beside the yan at the distance x is 1. (4) Theefoe, the pobability ( ) Z ( x) = 1 P, (5) whee P is given by equation (4). The so-called blackening function Z ( x ) can be obtained fom the expeimental investigation of images by using image analysis techniques. 3. Methodology 3.1 Mateial Used 100% cotton, oto spun, yans of counts 14.5, 0, and 9.5 tex, each spun at thee diffeent twist multiplies (Phix) of 65, 7, and 80 have been used fo the expeiment. 3. Expeimental Setup An imaging system has been developed using CC Camea, a micoscope, and optical fibe lighting. The CC camea is intefaced to the compute. Fo peliminay wok, a manually opeated device has been used to move the yan unde the imaging system. Fom the yan cone, yan is set to move unde the imaging system. Each image captues about 0.7 cm of yan length. Each pixel in the image coesponds to about x sq. micons aea. Afte each snap, yan is

3 nd INTERNATIONAL TEXTILE, CLOTHING & ESIGN CONFERENCE Magic Wold of Textiles Octobe 03 d to 06 th 004, UBROVNIK, CROATIA fowaded manually (typically 0 cm.). Afte captuing 800 images, MATLAB code is used to analyze the images. Automatic validation of the each image is done to discad any eoneous images. 4. Image Pocessing Example images captued fom the imaging system ae shown in Figue 6. Automatic thesholding is done by detemining point of inflection. Small holes ae filled with white pixels. Image is finally tansfomed into the image shown in image shown in Figue 7. Figue 6: Oiginal Image of the yan Figue 7: Pocessed Image of the yan Fo each pocessed image, yan axis is then automatically detected. To detect yan axis, each column is the image is scanned. Lagest white line is assumed as yan-body and its cente is then maked. This pocedue is epeated fo all the columns of each image. Yan axis is used to measue yan diamete and haiiness. Figue 8 shows yan axis in one the images. Figue 8:Yan axis maked in black 5. Results Fom the set of 800 images, many kind of numeical and gaphical infomation can be obtained. 1) Relative diamete (in tems of white pixels) along the yan length. Figue 9: iamete (in tems of white pixels) Along the Yan Length (9.5 tex) ) Aveage fibe distibution can then be calculated. Figue 10 shows the distibution diagams fo the thee samples. 3

4 nd INTERNATIONAL TEXTILE, CLOTHING & ESIGN CONFERENCE Magic Wold of Textiles Octobe 03 d to 06 th 004, UBROVNIK, CROATIA Figue 10: Fibe istibution iagam (fo 14.5 tex, thee twist coefficients ) 3) Yan haiiness using Necka's haiiness equation. Results have been compaed with USTER 3 test esults and ae shown below in Table 1. Table 1: Haiiness Measuement using two Methods: TUL and Uste Method Yan TUL IH (mm) Uste(cm/cm) 14.5, , , , , , , , , IH: Integal chaacteistic of total haiiness 0.03 Linea egession y = x R = TUL Haiiness Uste Figue 11: Coelation Gaph of TUL Haiiness Vs. Uste Haiiness 4

5 nd INTERNATIONAL TEXTILE, CLOTHING & ESIGN CONFERENCE Magic Wold of Textiles Octobe 03 d to 06 th 004, UBROVNIK, CROATIA Haiiness Vs Fineness Haiiness Fineness 65 am 7 am 80 am Figue 1: ependence of haiiness on Fineness (and Twist as well) CV dia have been measued fom the captued images. Results have been compaed with USTER 3 test esults and ae shown below in Table 1. Table : Results of CV dia at Vaious Cut Lengths and Compaison with Uste Yan TULCV dia (~0 cut length) Method TULCV dia * (1cm cut length) UsteCV m * (1cm cut length) 14.5, , , , , , , , , *CV dia and CV m have been epoted to be highly coelated 4) Vaious paametes of haiiness have been calculated. Effect of yan twist and its fineness have been seen and tabulated below in Table 3. Table 3: Haiiness Paametes of Theoetical Model fo Vaious Yan Counts and Twist Coefficients Paametes of Theoetical Model Yan h1 h µ 1 µ 14.5, , , , , , , , ,

6 nd INTERNATIONAL TEXTILE, CLOTHING & ESIGN CONFERENCE Magic Wold of Textiles Octobe 03 d to 06 th 004, UBROVNIK, CROATIA h1 Vs Fineness h Vs Fineness h am 7 am 80 am h am 7 am 80 am Fineness Fineness a. h 1 Vs Fineness b. h Vs Fineness Figue 13: ependence of Haiiness Paametes on Fineness (and twist coefficients) 6. iscussion Fom the Tables 1 and, it is evident that esults fom ou method ae in good ageement with the esults of USTER testing, see Figue 11. Fom Figue 1, it can bee seen that haiiness inceases with fineness if twist is much below the optimum twist (see case of 65 am). Gaph fo twist vs. total haiiness show a high negative coelation. With incease in twist, haiiness deceases. The same tend is evident in cases of elation between fineness and haiiness paametes viz. h 1, h, see Figue 13. Othe two paametes µ 1 and µ seem to be statistically constant. 7. Conclusion The poposed method can be used as a eliable, epoducible instumental method fo measuement of yan paametes. It not only gives highly coelated esults with woldly accepted USTER esults, but also gives moe detailed infomation about yan and its haiiness. Futhe wok is necessay to standadize the method. Acknowledgment This eseach wok is suppoted by Reseach Cente of Textile, gant no. LN00B090. Refeences [1] Riddle E. R.; Aminuddin N.; and Li E. S, Peliminay Examination of Long Sequences of Yan Capacitive and Optical Evenness ata, 10 th Engineeed Fibe Selection Reseach Foum, Novembe 6-7, 1997, Raleigh, NC. [] Necka B. and Voboova J., A New Appoach fo etemination of Yan Haiiness. 3 d Autex confeence, June 003 Gdansk, Poland. [3] Realff M. L.; Seo M., Boyee M.C.; Schwatz P. and Bake S., Mechanical Popeties of Fabic Woven fom Yans Poduced by iffeent Spinning Technologies- Yan Failue as a Function of Gauge Length, Textile Reseach Jounal, Volume 61(9), Autho(s): Jana VOBOROVA, M.Sc.;Pof. Ing. Bohuslav NECKAR, Ph.., Pof. Ing. Sayed IBRAHIM, CSc. Technical Univesity of Libeec, Faculty of Textile Engineeing, epatment of Textile Stuctues Libeec, Czech Republic Phone: +(40) Fax: +(40) Jana.VOBOROVA@vslib.cz Ashish Gag Technical Univesity of Libeec, Faculty of Textile Engineeing, epatment of Mateial Science Libeec, Czech Republic Phone: +(40) Fax: +(40) ashish.gag@vslib.cz 6