الفهرس 
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Abstract
Traditionally, twofold yarns have been used for weaving because they are stronger, and the twisting operation binds the surface fibers into the yarn structure so that it is smoother and more resistant to abrasion during weaving. The Sirospun process adapted some of the selftwist discoveries of CSIRO to the ring spinning technology of the worsted system, and combined spinning and doubling in the one operation. The technology maintains two separate strands during the spinning process, and this allows a number of fiberbinding mechanisms to operate before the strands are twisted about each other. An important aspect of the Sirospun system is a simple device to break out the remaining strand if one of the strands should be accidentally broken. Until now applications of Sirospun technique for producing twofold yarns in the sector of short staple spinning are limited. With the Sirospun process, a special spintwisted yarn can be produced directly on the ringspinning machine. In this process, two rovings are led in parallel through the drafting system, separated by two specially developed condensers, and drafted separately. The purpose of this work is to use the technique in short staple spinning by doing the following, firstly Investigate the properties of Sirospun yarns produced from Egyptian cotton fibers at various yarn linear densities, twist multipliers. Spindle speeds and strand space. Secondly Investigate the properties of Sirospun yarns produced from Bulked Acrylic fibers at various, twist multipliers. Spindle speeds and strand space. Also Analyzing the geometry of Sirospun yarn spinning forming zone, under industrial processing conditions. Then make a Comparison between Sirospun yarn characteristics with the equivalent single and plied yarns that produced at the same count. A simple attachment was designed to separate the two rovings to the predetermined spaces. Then the guides are mounted to conventional ring spinning frame to be acceptable to produce Sirospun yarns. To study the influence of the above machine parameters on the geometry of yarn forming zone and its interaction with yarn properties, we used two different colors of rovings with total count equivalent to one roving, which are used in the production. Each two different colors rovings are fed into each ceramic guide. A simple system contains a video camera and high frequency stroboscope is used to obtain a single frames. This frames was analyzed with special computer software to determine the overall geometrical properties of the yarn forming zone, such strand length, strand twist and convergence angle. The characteristics of the produced yarns were tested for their tenacity (g/tex), Elongation (%), irregularity (Cvm %), imperfections (thick, thin and neps per 1000m), Uster hairiness, frictional properties (dynamic coefficient of friction f, yarntoyarn) and Yarn bulk to investigate the influence of the above processing parameters on the yarn quality. Statistical analysis procedures show that there exist a significant effect of the strand space, twist multiplier and spindle speed on the characteristics Sirospun yarns. Results show an improvement in yarn qualities for example; yarn strength increased about 8%, hairiness also reduced with about 24%, for the same yarn count and twist. Finally, Sirospun yarns, that yarns produced in the sector of short staple spinning using conventional ring spinning frames mounted with special attachments, are completely establish the three common ways for developing, increasing productivity, improving quality and reducing processing cost.