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1

Control Optimisation of the New Drive of Small Diameter Knitting Machines

Skřivánek J., Bílek M., Kašpárek M.

Autex Research Journal

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2017

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Vol. 17, no. 1

1--5

EN

The article is concerned with the issues of the drive of small diameter knitting machines. In connection to the proposal of optimum structure of the driving systems of the machine, there have been analysed the possibilities of precisely controlled servo drives. An optimised structure of the drives allows for the utilisation of precisely defined position and velocity functions. There is applied here the function of a polynomial of 7th degree, proposed for impact-free course of the acceleration, and it is compared with the results corresponding to the existing structure of drives of knitting machines. At the same time, there is analysis and comparison of the consumption of electric power by the original and optimised systems.

2

Mathematical Modelling of the Heald Shaft

Bílek M., Kovář S., Skřivánek J.

Autex Research Journal

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2016

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Vol. 16, no. 4

175--181

EN

The manufacturers of weaving equipment recently endeavour to minimise the necessary designing plays in the weaving loom mechanisms. One of the mechanisms most exposed to stress is the shedding motion that defines the held-shaft stroke. Its end part is the heald shaft. The heald shaft constitutes a problematic assembly of the shedding motion. The design employed presently is characterised by dynamic impact loading caused by designing play in the suspension of healds into the heald shaft. During weaving cycle, the healds fly between the main beams of the heald shaft, producing a considerable force pulse. This paper is concerned with the description of dynamic behaviour of the existing design on the basis of mathematical modelling and verification of obtained results by means of experimental analysis.

3

Mechanical Properties Of Traditional And Nanofibre Textiles

Ursíny P., Bílek M., Moučková E., Pokorná M., Tumajer P., Wiener J.

Autex Research Journal

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2015

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Vol. 15, no. 3

198--206

EN

This study deals with a comparison of mechanical properties of a conventional yarn and a textile from nanofibres. The conventional yarn represents the textile objects with high degree of orientation of fibres and the textile from nanofibres represents the textile objects with low degree of orientation of fibres. The theoretical section is concerned with the issue of internal structure of plied yarn and resulting differences in the orientation and straightening of fibres and in utilisation of deformation properties of fibres in comparison to the referred nano textile. The experimental section describes the manner of realisation of both static and dynamic tests of conventional yarn and strips of nanofibres. The results show differences in the mechanical properties of conventional yarn and textile strip from nanofibres under static and dynamic loading conditions. The processing technology of conventional yarn has been verified in the long term. But textiles from nanofibres are a relatively new material and mechanical properties of the detected differences point out possible problems with their behaviour during standard technological processes.

4

Mathematical Model of the Heald with Damping Element

Bílek M., Skřivánek J.

Autex Research Journal

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2015

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Vol. 15, no. 1

1--7

EN

This study focuses on the analysis of the existing design solution of shedding mechanism. It is characterised by a heald attachment into the heald shaft with a necessary design allowance. The preparation of a mathematical model for the new concept of the heald attaching to the heald shaft frame is explained in this study. A damping element for dissipating the energy created during the heald impact on the carrying wire of the heald shaft is currently used for the high-speed weaving loom. This system makes use of a damping element, fitted in the profile of the rod at an optimum distance from heald eye. This element provides for reduction of the heald velocity before its drop upon the supporting wire because the opposite section of the heald is pressed into the rubber element. The calculated results of the new concept of the heald attaching to the heald shaft frame are compared with the existing solution without application of the damping element.

5

Mathematical modeling of the system shedding motion – heald – warp

Bílek M, Skřivánek J.

Autex Research Journal

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2013

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Vol. 13, no. 2

44--50

EN

The paper is concerned with the description of a mathematical model meant for an analysis of the movement of healds during the weaving cycle. The referred model consists of a mathematical description of shedding motion, coupled with the solution of the heald model of a weaving loom. Principal designing elements of this component have been considered while devising this model. The affected calculations show a high value of acceleration of the heald produced after its drop upon the supporting wire. The referred model allows for analyzing a considerable part of designs of heald shaft that are employed in weaving looms nowadays.

6

Influence of structure of the yarn on mechanical characteristics of yarns exposed to dynamic stress

Tumajer P., Ursíny P., Bílek M., Moučková E., Pokorna M.

Autex Research Journal

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2012

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Vol. 12, no. 2

44--49

EN

This paper is a direct follow-up of the paper [1] describing in detail the VibTex equipment, which facilitates testing of textiles in a wide range of frequencies of their extension, as well as the determination of corresponding dynamic modules and loss angles. This equipment has been employed for testing polyester yarns of concordant fineness manufactured on ring and rotor spinning frames. At the same time, the material concerned has been subjected to a standard strength test. Therefore, the results of experimental measuring published in this paper allow us to assess the effect of the chosen spinning technology upon the mechanical properties of polyester yarns both at their static and dynamic loading. The introductory section of the paper contains a theoretical analysis of the effect of the chosen manner of spinning upon the mechanical characteristics of yarns. The experimental section indicates the results of measurements at static and dynamic loading, and the final section of the paper confronts the obtained pieces of knowledge with theory. This paper is part of a larger group of publications concerned with the behaviour of various linear textiles when exposed to dynamic loading (see [1],[2], [4], [5], [6]).

7

Research Methods for the Dynamic Properties of Textiles

Tumajer P., Ursíny P., Bílek M., Moučková E.

Fibres & Textiles in Eastern Europe

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2011

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Vol. 19, no. 5 (88)

33--39

EN

This paper is concerned with a theoretical description of the dynamic properties of textiles and their experimental analysis. In the theoretical section of the paper, the dynamic properties of textiles are described based on rheological models. To describe their dynamic characteristics, the Laplace transformation has been employed. The experimental section of the paper describes special equipment - VibTex and the possibilities of its use in the experimental analysis of the dynamic properties of textiles. The experimental section includes a description of the manner of determining the dynamic properties of textiles based on the results of measurement.

PL

W artykule omówiono zależności dotyczące właściwości dynamicznych tekstyliów oraz opisano badania eksperymentalne. Zależności teoretyczne oparto na opracowanych modelach. Dla opisania właściwości dynamicznych zastosowano transformaty Laplacea. W części eksperymentalnej przedstawiono VidTex - specjalne urządzenie do badan dynamicznych oraz możliwości jego zastosowania. Artykuł zawiera opis sposobu uzyskiwania parametrów dynamicznych tekstyliów.

8

Use of the VibTex vibration system for testing textiles

Tumajer P., Ursíny P., Bílek M., Moučková E.

Autex Research Journal

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2011

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Vol. 11, no. 2

47--53

EN

Principal objective of this paper is a description of a special testing device (VibTex). This device allows testing of textile materials (threads, samples of fabrics, etc.) during cyclical stress at a high frequency. Control of the VibTex allows harmonic and non-harmonic elongation of the textile samples. Results of the tests with harmonic elongation can be used for calculations of the dynamic characteristics of textile samples. In the final part of the paper, values of the dynamic modulus and loss angles are determined at frequencies of 10 Hz and 100 Hz for various yarns.

9

Szkolne modele ogniw paliwowych

Opatrný P., Bílek M.

Chemistry-Didactics-Ecology-Metrology

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2007

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R.12, NR 1-2

31--35

PL

Spalanie „klasycznych źródeł energii" (węgla, ropy, gazu itp.) powoduje znaczne obciążenie ekologiczne. Dlatego też niezbędne jest poszukiwanie optymalnych warunków wykorzystania tzw. „odnawialnych źródeł energii", np. energii słonecznej, wiatrowej i wodnej. Problemem jest, jak tę czystą energię możliwie najefektywniej magazynować w celu dalszego wykorzystywania. Właśnie wodór, pozyskiwany z użyciem ekologicznej wtórnej metody elektrolizy wody, staje się zadowalającym medium magazynującym. Zestaw funkcjonalnych modeli szkolnych służących do demonstrowania „odnawialnego systemu" składa się z ogniwa słonecznego, elektrolizera oraz ogniwa paliwowego podłączonego do obwodu elektrycznego. Ogniwo słoneczne zamienia energię słoneczną na elektryczną dzięki elektronom obecnym w warstwie n płyty krzemowej. Tak pozyskana energia w elektrolizerze rozkłada wodę w procesie elektrolizy na wodór i tlen. W szkolnych modelach ogniw paliwowych, w temperaturze pokojowej, przebiega synteza wodoru i tlenu, podczas której następuje zamiana energii chemicznej na elektryczną. Z punktu widzenia chemii chodzi o niskotemperaturowe elektroutlenianie wodoru. Podstawą działania elektrolizera i ogniwa paliwowego jest membrana PEM (Proton Exchange Membrane lub Polymer Electrolyte Membrane), za pośrednictwem której odbywa się jednokierunkowy transport jonów H+. Połączenie systemu elektrolizera oraz ogniwa paliwowego obrazuje szkolny model samochodzika napędzanego niskotemperaturowym ogniwem paliwowym. Modele takie są dostępne handlowo.

EN

Combustion of energy resources, like coal, oil, earth gas, causes a hard environmental damage. It is necessary to find an optimal usage of the so-called "renewable energy resources", like energy of Sun, wind and water. The problem is how to most effectively store a "pure energy". Hydrogen, produced by the ecological reversible method of the water electrolytic process, is the most advantageous medium to storage. A set of school functional models to demonstrate "renewable system" consists of a solar cell, electrolyzer and fuel cell connected to an electric circuit. A solar cell converts solar energy into electric one. Energy acquired in the electrolyzer splits water into hydrogen and oxygen. A synthesis of hydrogen and oxygen into water proceed at room temperature in the fuel cell teaching model. A chemical energy converts into the electric one during the synthesis. From the chemical point of view it is a low temperature electrical oxidation. The core of both electrolyzer and fuel cell is PEM - Proton Exchange Membrane or Polymer Electrolyte Membrane through which a one way transmission of H+ ions is realized. Connecting both system of electrolyzer and fuel cell is represented by a school car model powered with a low temperature reversible fuel cell. The models are available commercially.