23—the Significance of Yarn Tension in Open-End Spinning

Krause, Hartmut; Soliman, H.A.

doi:10.1080/00405007608630561

Cited by 9 publications

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“…As the twisted yarn is pulled ou t of a guide on the axis of the pot it lashes round the wall gathering and twisting in t he newly arrived individual filaments. The East European mathematicians moved in very rapid ly, leaving relatively poor pickings for those in the West (12,27).…”

Section: Mathematics In the Textile Industrymentioning

confidence: 99%

A simple model of the melt fracture instability

Greenberg

Demay²

1994

Eur. J. Appl. Math

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We develop and analyze a system of equations describing a molten linear polymer being extruded in a capillary rheoineter which is operating under the controlled condition that the mean velocity at the capillary inlet is maintained at a constunt iial,ue. Slipping of the melt at the pipe wall is permitted and an evolution equation for the boundary slip parameter is postulated. The combined system governing the mean cross-sectional velocity and slip parameter is S~O I L~I Ito exhibit relaxation oscillations similar to those observed in actual rheometers. Capillary EquationsOur modelling effort accounts for what happens in the capillary tube and not in the reservoir. We assume the flow in the capillary is axisymmetric and that all quantities depend only on T , z and t . We let p denote the polymer density, p denote the pressure, and assume that the velocity fieldThe governing equations are the continuity and balance of momentum in the directions e,, es, and e3. At the boundary, r = R, we assume thatwhere F 2 1/4 is a dimensionless quantity depending on z and t and ~~( z , t ) = T(R, z , t ) is the wall shear. We further assume that the polymer is slightly compressible and that the following equation of state holds between the density and pressure:Here, po and po are reference values of the density and pressure and 0 < ~1 << 1 is a dimensionless small parameter.To assess which terms in this sytem are important and which may be neglected we cast the system in dimensionless form. We let, 2E1171 POE2 r = Rrl, z = L z l , and t = T t l and (4) where 0 < ~1 = f << 1. With these scalings the shear stress becomes where A syst,ematic perhrbation analysis where we assume that 0 < E I << 1, 0 < ~2 << 1. and 0 < << 1 514 yields ZAMM . Z. angew. Math. Mech. 76 (1996) S4 and The continuity equation, averaged over the cross-section, reduces to dt, 8Pl -8 (FZ) = 0 , o < z1 < 1 with boundary conditions 8Pl 8z1 -F(O,tl)-(O,tl)= q and p(1,t)l) = 1. Modelling of the Wall Parameter -FFor molten polymers one typically observes two distinctly different steady flow regimes. In each regime the (dimensionless) mean velocity GI, (dimensionless) pressure gradient 2, (dimensionless) wall shear T: , and slip parameter F are independent of z1 and t l as shown in Figure 1. The first flow regime exists for mean flow rates 6 1 5 2. In this range the capillary flow is Poiseuille with no-slip at the boundary; that is F 5 1/4. The second regime persists for (dimensionless) mean velocities satisfying GI 2 F2c2 > 2 and corresponds to a capillary flow with constant slip parameter F2 > 1/4 at the capillary wall. Hence and Experimental evidence indictes that the wall shear c1 corresponding to the mean flow % exceeds the wall shear c2 corresponding to the mean flow F~c z .In general one finds no stable steady flows for incoming mean flow rates G l ( 0 , t ) q E (2, F2c2) but one observes oscillatory flows. Figure 1 515Motivated by t,hese observations, we assume the existence of a switch curve (scaled as shown in Figure 1) and assume that at. each point tl th...

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Section: Mathematics In the Textile Industrymentioning

confidence: 99%

A simple model of the melt fracture instability

Greenberg

Demay²

1994

Eur. J. Appl. Math

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“…Here, the second part of the equation (1) is because of the centrifugal force acting on the yarn inside the rotor and majorly, contributing to the generation of yarn tension. Hence, many researchers (Shepherd, 1969; Stalder, 1972; Grosberg, 1973; Brandis, 1975; Krause and Soliman, 1976) have ignored the first part of the equation, i.e. T 0 on the ground that it is much smaller than the second term.…”

Section: Introductionmentioning

confidence: 99%

An experimental verification on existence of air-drag force influencing yarn tension during rotor spinning

Chattopadhyay

Venugopal

2020

RJTA

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Purpose Most researchers have neglected the effect air-drag force on yarn tension during rotor spinning. This paper aims to study the effect of rotor air-vacuum pressure in conjunction with opening roller speed and yarn linear density on the yarn tension generated during the rotor spinning, which has established their significant influences on both the mean and the peak tension.This is the first of one-of-a-kind experimental study being reported to demonstrate the influence of air-drag force on yarn tension during the rotor spinning under dynamic condition. Design/methodology/approach The dynamic measurements on yarn tension at the exit of the doffing tube were carried out by using an electronic capacitive yarn tension meter during rotor spinning. The derived experimental data were fitted into equations to construct the response equations and to work out the coefficients of multiple correlation between the data and the predicted equation for both the mean and the peak tension. Various surface plots were constructed by using those response surface equations, so as to study the effect of variables on yarn tension generated during the rotor spinning. Findings The study has established that the rotor vacuum is responsible in causing a change in yarn tension, it increases with the decrease in air-vacuum inside the rotor. The involvement of the opening roller speed in altering yarn tension during rotor spinning has been proved. As the opening roller speed changes, so does the air stream surrounding the opening roller speed with consequent alteration of the centrifugal force generated due to the rotation of the rotor. The centrifugal force and, hence, the yarn tension generated in the rotor will be simultaneously affected by both the rotor relative vacuum and the opening roller speed. Research limitations/implications This is a structured experimental study to verify the influence of air-drag force generated during rotor spinning on yarn tension. Very limited theoretical work has been carried out in this direction as reported in the introductory part of the paper. The result of the present study will encourage future researchers to revisit the theory on generation of air-drag force during rotor spinning and work out a new formula. Practical implications Next only to the conventional ring spinning system, the rotor spinning holds the second place in the share of global yarn production. Because of its advantage of lower cost of production and amenability to automation, the rotor spinning has gained acceptance in spun yarn production, particularly for spinning coarse and medium counts of yarns. Currently, it has acquired about 25 per cent share in the world’s spun yarn production. As many of the rotor machine variables significantly affect fibre configurations and, subsequently, the yarn properties by influencing the airflow characteristics inside the rotor unit, the study of yarn tension during rotor spinning and its analysis assumes a significance. Social implications Rotor spinning is a relatively new and faster method of conversion of discrete fibres into continuous staple yarn and, subsequently, various textiles and garments. Its yarn is distinct and a bit different compared to the conventional ring yarn. It has got wide acceptance in the market and fashion. As such, the spinning sector that converts fibres into yarns is an important industry world over, providing employment to many. Besides, being the basic operation in the fibre value chain, it supports many downstream activities, including human clothing and fashion. Thus, the research on rotor spinning, particularly the yarn engineering to produce better products will be helpful to strengthen and grow the textile value chain. Originality/value This is an original research study. The magnitude and the direction of the air drag on the yarn during rotor spinning is very difficult to assess. Thus, most researchers for the sake of simplicity in analysis have neglected its effect on yarn dynamics, but a few of them have taken note of it in their theoretical propositions. However, no experimental result has been reported so far in the literature, supporting the influence of such air-drag force on yarn tension in the rotor spinning. In fact, none of the above studies have considered the induced effect of centrifugal force caused because of the rotation of the opening roller on the airstream that flows from the transfer channel inlet into the rotor because of its partial vacuum, causing consequential effects on air-drag force and tension in the yarn inside the rotating rotor. This is the first of one-of-a-kind experimental study being reported to demonstrate the influence of air-drag force on yarn tension during the rotor spinning under dynamic condition.

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“…Враховуючи те, що системи контролю та регулювання натягу ниток на технологічному обладнанні є, переважно, механічними та контактними [1, 2], то їх застосування не дає можливості оперативного технологічного визначення натягу. Існуючі контактні механічні засоби вимірювання натягу [3,4] здійснюють вплив безпосередньо на сам текстильний матеріал. Це може призводити до виникнення додаткового натягу матеріалу при його контролі, що може вносити суттєву похибку вимірювання основного натягу.…”

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Застосування Ультразвукового Методу З Повздовжнім Розповсюдженням Хвилі Для Вимірювання Натягу Текстильних Матеріалів

ЗДОРЕНКО,

МАТЯШ

2023

ВОТТП

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В роботі розглянуто можливість застосування ультразвукового методу вимірювання натягу текстильних полотен з повздовжнім розповсюдженням хвилі у волокнах контрольованого матеріалу. Застосування такого методу для контролю натягу матеріалу дозволить оперативно визначати зазначений параметр в процесі виробництва. Це дозволить у майбутньому вдосконалити текстильні машини для виготовлення готових полотен та стрічок із поточною корекцією натягу матеріалу безпосередньо на технологічному обладнанні із використанням безконтактних датчиків.

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23—the Significance of Yarn Tension in Open-End Spinning

Abstract: The theoretical relation between yarn-mass variation and the variation of yarn-spinning tension lor open-end rotor-spinning is derived, and it is shown experimentally that spinning-tension measurement represents a useful means of assessment of yam irregularity.

Cited by 9 publications

References 1 publication

A simple model of the melt fracture instability

A simple model of the melt fracture instability

An experimental verification on existence of air-drag force influencing yarn tension during rotor spinning

Застосування Ультразвукового Методу З Повздовжнім Розповсюдженням Хвилі Для Вимірювання Натягу Текстильних Матеріалів

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