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Textile Research Journal

DOI: 10.1177/0040517586056003081986; 56; 207Textile Research Journal

A. Manich, D. De Castellar and A. BarellaAcrylic Staple Spun Yarns

Influence of a Yarn Extractive Nozzle on the Apparent Loss of Twist in Rotor Open-End

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Influence of a Yarn Extractive Nozzle on the Apparent Loss of Twist inRotor Open-End Acrylic Staple Spun Yarns

A. MANICH AND D. DE CASTELLAR

Instituto de TecnologaQumicay Textil, CSIC, Barcelona, Spain

A. BARELLA

Barcelona, Spain

ABSTRACT

The influence of a yam extractive nozzle on the apparent loss of twist or "residualtwist" has been studied for rotor open-end acrylic staple spun yarns. Four factors werestudied: two quantitative factors - yam linear density at three levels and yarn twistmultiplier at five levels, and two qualitative factors - three nozzle types and four rotortypes. The analysis of results showed that both rotor type and extractive nozzle typeexert a significant influence on residual twist, which tends to increase when the nozzle

produces an increasing false twist effect on the yam and to decrease when yarn frictionagainst the rotor increases. Residual twist increases significantly in a linear mannerwith both yarn linear density and twist multiplier. The nozzle type interacts significantlywith all other factors (rotor type, yam linear density, and twist multiplier). An inter-action between yarn linear density and twist multiplier has been also detected. Generallyboth nozzle type and twist multiplier exert a significant influence on the residual twistcoefficient of variation.

The extractive nozzle effect on twist insertion in rotor

spun yarns, the false twist effect, and the influence of

rotor parameters on the aforementioned twist insertionare topics that have been studied in detail (see literaturelist, 1 through 18). The apparent loss of twist or &dquo;re-sidual twist&dquo;is an important phenomenon in industrialpractice because the noncoincidence between &dquo;ma-chine twist&dquo;and &dquo;yarntwist&dquo;represents a disturbance.

In such twist difference, influences from many fac-tors are superimposed, mainly the rotor type and theextractive nozzle dimensions and surface, because oftheir influence on false twist generation.

In this study, we discuss the influence of several fac-

tors (yarn linear density, twist multiplier, nozzle type,and rotor type) on the apparent loss of twist in rotoracrylic staple spun yarns.

Experimental An acrylic staple of 40 mm effective length, 1.6 dtex

and 22.88 cNtex (Stelometer 1/s&dquo;gauge) was fur- -nished as a second draw frame passage sliver of 2.613tex linear density and Uster CV = 2.95% unevenness.

The yarn was spun on a BD 200 S machine. The

opening roller was specially designed for synthetic fi-bers ; its speed was 6,000 t ~ min-and the 66 mm di,ameter rotors worked at a speed of 36,000 t ~ min-.

Four rotor types, F-72, ND-7, H, and J, described inreference 6, were combined with three extractive nozzle

types: A - exterior diameter at the entry of the funnel:13.5 mm, smooth; B - exterior diameter at the entryof the funnel: 19.5 mm, smooth; and C - exterior di-ameter at the entry of the funnel: 19.5 mm, grooved(4 grooves). All possible combinations were tested (4X 3 = 12 spinning heads).

Tests were planned as four variables factorials onthe basis of three levels of yarn linear density (20, 25,30 tex) five levels of yarn twist multiplier (22, 32, 36,40, 44 t cm- - ~ tex~2),four rotor types, and three noz-zle types. Table I summarizes the experiments showing

theoretical twist valuesand real machine twists

appliedto the yarns.The spinning machine was adjusted to achieve twist

values nearest the theoretical ones, but in one instanceit was unable to obtain a good approach because ofmachine technical limitations.

Apparent yarn twist was determined by means ofthe untwist-retwist method [ 15].Thirty 500 mm lengthtest specimens were measured for each case. The dif-ference between Tm &dquo;machinetwist&dquo;and Ty &dquo;yarntwist&dquo;was expressed as a percentage:

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TABLE I. Planning of experiments. Rotor types: F-72, ND-7, H, J (qualitative factor at four levels). Nozzle types: A, B, C. (qualitativefactor at three levels). -

Tl~percentage Tr is called &dquo;residualtwist&dquo;as otheraujnors have done [ 10].

Results, Statistical Treatment,and Discussion

The results are shown in Table II in terms of signif-icance of main effects and interactions in function of

rotor type, after mathematical treatment of experi-mental values by means of an HP 85 minicomputer.The notation for the considered factors is as follows:B - nozzle type, R - rotor type, M - yarn linear density,T - yarn twist multiplier. L is the linear effect and Qis the quadratic effect.

Table II shows that the nozzle type effect and bothlinear effects of yarn linear density and twist multiplierare significantat the 1 %level for all rotor types, whereasthe B X T and B X M interactions, as is true for theML X TL, are also significant.

Figure 1 shows the main effects of nozzle type andthe linear effect of yarn linear density by averaging for

FIGURE 1. Yarn linear density, main effect, and B x M interactionas a function of nozzle type, byaveraging over twists and rotor types.

each nozzle type over both twists and rotor types. This

graph also shows the B X M interaction due mainly tothe C-type nozzle. Figure 2 shows the yarn twist linear

TABLE!!. Significance of main effects and interactions as a function of rotor type.

Degreesof freedom.



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FIGURE5. Rotor main effects as a function of twist multipliersby averaging over nozzles and yam linear densities.

TABLE IV. Rotors and nozzles: main effects and interactions.

.

FIGURE 6. Nozzle and rotor behavior.

H rotor has been considered independently of the otherthree because of its special geometry [! 1]. This rotorhas a collecting groove angle of 45, whereas in theother rotors such an angle is 35. The rotor wall widthis 9 mm for the H rotor and 14 mm for the others.. From Figure 6 it appears that residual twist dimin-ishes when the friction of the yam against the rotorincreases, and it rises when the effect of false twist in-creases in the extracting nozzle.

Finally the residual twist coefficient of variation val-ues has been analyzed. The analysis of variance cor-responding to this study is summarized in Table V.

Except for the H rotor we verified significant effectsof nozzle type and yarn twist multiplier, as well as someinteractions considered less important. The behaviorof the F-72 rotor in relation to the significant effect ofyarn linear density and the MLX TL interaction, which

do not appear for the other rotors, can also be consid-ered as occasional. In fact, confidence limits for CVestimations are larger than for the mean, and the actualsample size is too small for it to be judged sufficientlyreliable for variability measurements. In general thecoefficient of variation of the residual twist increaseswith both twist multiplier and the increasing effect offalse twist generation in the yarn bynozzle action (types

A to C). ~ .

Conclusions

Both rotor type and extractive nozzle type exert asignificant influence on residual twist, which tends toincrease when the nozzle produces a rising false twisteffect and to diminish when the friction of the yam,against the rotor increases. The residual twist increasessignificantly and linearly with both yarn linear densityand yam twist multiplier.

Four significant interactions have been detected:nozzle X rotor, nozzle X yam linear density, nozzleX yarn twist multiplier, and yarn linear density X yamtwist multiplier. Generally speaking, both nozzle typeand yarn twist multiplier exert a significant influence

______ TABLE V. Significant effects and interactions for the CV of residual twist.

. Degrees of freedom.



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on the coefficient of variation of residual twist. The H

rotor, which has a different geometry in relation to theother rotors studied, behaves, in some instances, in adifferent manner.

ACKNOWLEDGMENTS

We are indebted to Mrs. C. Martinez for collabo-ration in the experimental work.

Literature Cited

1. Anon., Die Garnreibungund das Drehmoment am Ab-zugstrichter beim Rotorspinnen, Textil Praxis 32, 251-252 (1977).

2. Artz, P., and Hehl, R., Der Drehungsbeiwertbei Faden-bruch als Kennwert frdas OE-Spinnverfahren, Chem-iefasern Textil Anwendungstech. Ind. 24/76, 550-553(1974).

3. Barella, A., and Manich, A. M., Der Scheinbare Garn-drehungsverlust beim Rotorspinnen, Melliand Textilber.65,301-304 (1984).

4. Cormack, D.,et al., The Yarn Twist Inside the Rotor inOpen-End Spinning, J. Textile Inst. 70, 380-384 (1979).

5. Feldmiihle, A. G., Br. Patent 1.568.070.6. Gayler, J., and Schren, A., Rotorspinnen-Literaturau-

swertung und Eigene Erfahrungen, Chemiefasern An-wendungstech.Textil Ind. 27/79, 430-434, 591-599( 1977).

7. Kampen, W., et al., "Poaibilidades de lnfiuir y sus Um-ites, Sobre la Estructura de los Hilados Open-End deRotor, Int. Textile Bull. Spinning, 373-387 (1979).

8. Lord, P. R., and Giorgis, T., "Book of Papers for the17th Canadian Textile Seminar," Textile Tech. Feder-ation of Canada, Montreal, 1980, p. 51.

9. Lnenschloss,J., and Brockmans, J., Betrachtungen zumOE-Friktionsspinnen, Melliand Textilber. 63,175-181,261-263 (1982).

10. Lnenschloss,J., et al., Einfluss der Abzugstrichteraus-fhrungauf die Struktur von OE-Rotorgarnen,MelliandTextilber. 57,429-431 (1976).

11. Manich, A. M., Aspectos Estructurales de los Hilos deRotor de Algodn,Fifras Quimicasy Mezdas, doctoralthesis, Universidad Politcnicade Barcelona, 1980.

12. Schubert & Salzer Maschinenfabrik A.G., Br. Patent

1.529.404.13. Singh, S. P., private communication.14. Tura, J. M., Estudio de la Estructura y la Migracinde

las Fibras en los Hilos OE de Mezcla Polister/Algod&oacpor Medio de Trazadores Radioactivos y Fluorimetra,doctoral thesis, Universidad de Barcelona, 1976.

15. UNE 40 002, Medicion de la Torsinde los Hilos.

Manusaipt rereived May 21, /W3. awepted July 8. 1985.

Communications to the Editor

Further Evidence for the Presence of Cellulose I and II in the Same Cross Section ofPartially Mercerized Cotton Fibers

June 6, 1985

Dear Sir:

In a recent publication [1]] we have reported electronmicroscopic evidence to show that the bilateral struc-ture in native cotton fibers influences the conversionof lattice from cellulose I (C I) to cellulose II (C II)during alkali treatments. The presence of C I and C IIregions in the same cross section has been confirmedby distinct morphological differences at the ultra struc-tural level. This note presents further evidence obtainedby the cuene dissolution technique [2] for the existenceof C I and CII regions in the same cross section ofpartially mercerized cotton fibers.

The cuene dissolution technique has been used ex-tensively by earlier workers [2, 3] to evaluate chemicallymodified cotton; further cellulose II is more resistantto cuene than cellulose I. We therefore thought itworthwhile to use this technique to distinguish C I andC II regions occurring in the same cross section. In thisstudy, we treated layered cross .sections (obtained bythe same procedure as that given in reference 1 )ofnative, fully mercerized, and 13% NaOH treated cottonfibers with 0.4M cuene for 2 minutes. The washed anddried cross sections were coated with platinum andexamined in a Hitachi HU 11E electron microscopeat 75 kV.


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