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EN
The publication presents a theoretical study of the susceptibility of rheological models of threads to dynamic stretching in the context of modern, highly efficient textile technologies. Input parameters of the four analyzed models, the Kelvin-Voigt model, the Maxwell model, Standard model 2, and the Zener model, corresponded to the actual values of the coefficients of viscosity, elasticity, kinematic and dynamic loading, and stretching speed for the analyzed polyester silk threads produced in a knitting process, with knitting speeds from 700 to 1,600 courses/min. The research proves that the tested thread models behave differently in the stretching process-the Kelvin-Voigt model is sensitive to both the increases in kinematic loading and viscosity coefficient, Standard model 2 is only susceptible to dynamic stiffness, and the Zener model is significantly sensitive to kinematic loading. All responses of the models increase with the increase in stretching speeds. The obtained results indicate substantial “accuracy tolerance” in setting input parameters while identifying dynamics of the knitting process on warp-knitting machines.
EN
The present paper investigates the effects of knitted loop length on yarn fluctuation amplitude during feeding into a circular knitting machine. Variation of yarn tension causes a change in the loop length and yarn fluctuation amplitude. In order to study the behaviour of the yarn fluctuation amplitude during the feeding process, a new optical IR electronic monitoring system was designed and developed. Experiments were carried out on an industrial single jersey knitting machine with a plain knitted pattern and polyester 150 denier continuous filament yarn for three different knitted loop lengths. Evaluating the fluctuation amplitudes recorded by analysis of variance revealed that an increase in the loop length will cause a highly significant decrease in the yarn fluctuation amplitude.
PL
Zmiany naprężenia przędzy powodują zmianę w długości oczka i fluktuację amplitudy przędzy. W celu zbadania zachowania się przędzy podczas zmian amplitudy w czasie procesu wprowadzania przędzy do maszyny opracowano i wykonano nowy elektroniczno-optyczny (IR) system monitoringu. Badania przeprowadzono na przemysłowej dziewiarce dla dzianin o splocie lewo prawym stosując przędzę z ciągłych włókien poliestrowych o masie liniowej 150 dtex. Stosowano trzy różnej długości oczka. Ocena zarejestrowanych fluktuacji amplitudy oraz analiza wariancyjna wykazały że wzrost długości powoduje bardzo wyraźny spadek fluktuacji amplitudy przędzy.
3
Content available remote Optimisation of the warp yarn tension on a warp knitting machine
EN
Investigations (calculations) based on a warp yarn tension analysis on a warp knitting machine with multiaxial weft yarn insertion allow prospective reduced yarn tension differences in technical warp knits. From this a future opportunity is provided to substitute the subjective warp let-off adjustment by a model of tension control. The outcome of this is a higher reproducibility with associated increasing process reliability and rising product quality.
EN
In this article assumptions for the physical and mathematical general model of the knitting process, referring to both iso- and anisostructural warp-knitted fabrics, have been defined. In the course of the simulation and experimental research, the changability tendencies as well as the optimum construction parameters of warp-knitting machines were determined from the point of view of the minimum dynamic load of warp threads.
PL
Zdefiniowano założenie fizycznego i matematycznego uogólnionego modelu procesu dziania odnoszącego się zarówno do dzianin kolumienkowych izo- jak i anizostrukturalnych. W procesie badań zarówno symulacyjnych jak i optymalne parametry konstrukcyjne osnowarek ze względu na minimalne obciążenia dynamiczne nitek osnowy.
13
Content available remote Dynamics of yarn tension on knitting machines
EN
The submitted paper reports a study of investigation of the dynamics of yarn tension, i.e. to the time dependence of the yarn tension on large-diameter circular knitting machines (LCKM). The special feature of this study is the fact that predictions are made for the course of the yarn tension during a single stitch-forming process. Only the yarn tension in the area of the yarn feeder and the yarn guide eye can be measured. Some results of such experimental investigations have already been published [1,2]. In this paper, additional results of theoretical model calculations are presented. In particular, by these calculations it will be possible to determine the structure of the yarn tensile force at the knitting point, i.e. in the region between knitting needles. The calculation of the yarn tension required a numerical solution of a system of non-linear differential equations. The special difficulty lies in the formulation of the non-equilibrium state of the running yarn, especially in the formulation of the robbing-back effect.
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