tailieunhanh - Woven Fabric Engineering Part 8

Tham khảo tài liệu 'woven fabric engineering part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | c. Surface Properties Engineering 10 Surface Unevenness of Fabrics Eva Moucková Petra Jirásková and Petr Ursíny Technical University of Liberec The Czech Republic 1. Introduction Unevenness of plain textile is counted among qualitative parameters of fabric still more often. It shows itself for example in the appearance of plain textile fluttering cloudy appearance with thick and thin places as well as in a mass variation of fabric samples. The appearance of plain textiles is influenced by irregularity of yarns that plain textiles are made from and by manufacturing process of plain textile . by weaving or knitting. The yarn mass irregularity displays itself in the plain textile by specific known ways stripiness and a moiré effect . These faults are caused by a periodical irregularity of yarns. A non-periodical yarn irregularity gives cloudiness in the woven or knitted fabric. Parameters and characteristic functions of mass irregularity a spectrogram a variance length curve are usually used for the evaluation of unevenness of longitudinal textiles yarns Slater 1986 . The parameters indicate a value of irregularity. The characteristic functions describe a structure of mass irregularity and enable to find the causes of irregularity. We can predicate unevenness of plain textile surface unevenness on the base of course of the spectrogram as well as the variance length curve. Knowledge of these problems are already known and verified Zellweger Uster 1971 Zellweger Uster 1988 . Currently there are other possibilities for the prediction of surface unevenness. One of them is the application of so called a DR function Deviation Rate . It is determined for example by means of the Uster Tester IV-SX. Today studies of relation between the magnitude DR and surface unevenness are in progress. Instrumentation used for mass irregularity measurement for example the system Oasys from Zweigle the apparatus Uster-Tester IV-SX from Zellweger Uster makes among others simulation of .