Band 10, Heft 2

Doubling of sliver has ceased to be the fundamental operation for reducing the weight irregularity of spinning halfproducts, which are decisive for the quality of yarn. Its role has now been taken over by the general use of autolevellers. After leaving the regulation zone, card sliver, whose weight irregularity is reduced by a short-term autoleveller, undergoes a process of relaxation. This phenomenon takes place only in the case of regulated sliver. Unregulated slivers passing through a leveller operating with constant draft show few relaxing properties. One reason why autolevelled card sliver has such relaxing properties may be the variation of the drafting force caused by the continually changing draft. The performance of the short-term card autoleveller cannot be unequivocally evaluated. The main difficulty lies in the time span between levelling and measurement, during which the sliver undergoes relaxation. How quickly the autolevelled card sliver is fed to the next machine in the yarn manufacturing process is therefore important, because in the intervening time the initial irregularity of the product may undergo uncontrolled changes.

Modern textile and clothing manufacturers can today use the entire range of conventional CAD/CAM systems together with new computer graphics and Internet-based technologies in order to strengthen their position on the market, building a completely new electronic-business offer. Graphical presentation of textile products and processing, or visualisation, presents a promising technology that can be treated as a potential enrichment of conventional computer aided technologies used today by the majority of advanced producers of textile fabrics, clothing, and other textile products. The article presents the results of research on designing computer software for visualising the fabric dyeing process. The program package produced enables the effective visualisation of two fabric dyeing processes: a Pad-Batch machine line for dyeing flat textiles in open-width state, and an HT overflow dyeing machine for fabric dyeing in rope form. Graphical applications of both dyeing processes can be used for both industrial and educational purposes. In this article, we focus more on presenting the program structure and functionalities for using the software to support the education of textile students.

The cover factor of Jacquard decorative knitted fabrics determines the quantity of light going through the knitted material. By changing the fabric cover of the knitted material it is possible to influence both the aesthetic and functional features of the product. The intensity of light transmission, determined on the basis of an instrumental method of measuring the light-barrier properties of knitted decorative products, was correlated with values of the fabric cover determined on the basis of both theoretical analysis and experiments.

Unevenness of woven fabric results from irregularity of the yarn used as well as from the process of its manufacture (weaving). A periodical and non-periodical yarn irregularity shows itself in the flat textile by known effects - the moiré effect, cloudiness, and stripiness. It is possible to predict the appearance of flat textiles from measured values of yarn mass irregularity and their characteristic functions (a spectrogram, a variance-length curve). The evaluation of surface unevenness of woven fabrics is done not directly but by judging their appearance, most often subjectively. For evaluation of flat textile appearance, it is also possible to use a so-called area-variation curve. The curve can be constructed on the basis of analysis of a woven fabric image either by a special program, created by J. Militky (Technical University of Liberec) in the programming environment Matlab, or by means of image analysis. By these methods it is possible to evaluate an image of real flat textile as well as a simulated image from an apparatus for yarn irregularity measurement. The woven fabric image is in grey scale. The variation coefficient of greyness degrees expresses the unevenness of flat textiles. In the experiment both real woven fabric images and simulated appearances of woven fabric, obtained by means of the apparatus Uster Tester IV, are evaluated by the methods mentioned above. The acquired area-variation curves are compared with each other and compared with visual evaluation of the woven fabric image. It was found that area-variation curves show only marked unevenness of woven fabric.

Thermal transfer foils like Flex and Flock are novel decorative materials for textiles. They are very attractive due to ease of use, simplicity of application, and the possibility of achieving unusual effects. This technology requires preparation of a digital image for digital cutting and/or printing plotters. This paper describes these materials, their structures, advantages, and techniques of application.