Study On The Rotor Spinning Technology Of The High-count Cotton Noil Yarns

In the past half century,with the development of the rotor spinning and application of rotor-spun yarns continue to expand in China,medium and fine yarns have gradually added their shares in yarn market,but mills are continuously shrinking their revenues,yet the density of rotor yarns is decreasing.Cotton noil,one of the spinning materials in common use,still maintains an important role in the market in manufacturing the low or medium count yarns for the short length of fibers.At the present,medium or fine rotor-spun yarns based on the cotton noil have been little investigated.If textile enterprises can make full use of cotton,they are likely to not only obtain considerable economic interests,but also save resources,protect the environment and yield social benefits.This paper make a preliminary research on spinning elements and main technical parameters,with cotton noil from long-staple cotton as materials foe spinning experiments of 14.6tex(40s)yarn in DS60 semi-automatic rotor spinning machine.First of all,the factors of rotor spinning are modified based on the spinning experience of mills and workers for reference,including machine equipment,spinning elements,main technical parameters and temperature and humidity of workshop,in order to preliminarily spin the 14.6tex rotor-spun yarn.Experimental results indicated that the yarn are prone to breakage with poor strength in the spinning process,which provided the basis for the subsequent spinning experiment.Then,key components of rotor spinning process including the rotor diameter,different models of combing roller and false-twister are also optimized by orthogonal experiment of 3 factors and 3 levels adopting the table of)3(49L.Conducted range analysis and variance analysis on 4 indicators like single yarn breaking intensity,yarn evenness,number of harmful hairiness and 280% nep counts.It is found that 2 kinds of analysis methods for the significance of different factors and the optimal combination are not the same,and fuzzy analysis method is used on 4 indices of yarn quality to make comprehensive evaluation and analysis of significance levels of various factors: rotor diameter > model of combing roller > specification of false-twister.After spinning experiment with preferred elements combination,the yarn quality is better than before,which showed the optimal combination of spinning elements: T-type condensing groove and the diameter of rotor is 33 mm,combing roller model is OK40,curvature radius of the ceramic spiral false-twister is 6mm.Compared with trail yarns,the quality of yarn with preferred element combination increased breaking strength by 11.21%,reduced the number of harmful hairiness by 28.24%,enhanced evenness by 10.16% and lowed 280% nep counts by 22.69%.Finally,based on the above element combination,the design of single-factor experiment and comprehensive analysis of rotor-spun yarns are made to confirm the valid range of 3 main technical parameters(rotor speed,combing roller speed and twist multiplier).Then,rotational and combinational design of quadratic regression with 3 factors is carried out to optimize the experimental scheme and test the performances of yarns including breaking strength of single yarn,elongation at break,strength irregularity,the number of harmful hairiness,yarn evenness,+50% slub counts,-50% thin place counts and 280% nep counts.The quality indexes are optimized by MATLAB software,and the effective regression equation is established by screening the regression equation and the regression coefficient.After computing,with preferred parameters combination is implemented,and the yarn quality is also better than before,which indicated the optimal combination of technical parameters: rotor speed is 84152r/min,combing speed is 7905.5r/min and twist multiplier is 564.5.Compared with previous spinning yarn,the quality of yarn with preferred parameters combination increased breaking strength by 6.67%,reduced the number of harmful hairiness by 2.5%,enhanced evenness by 0.65% and lowed 280% nep counts by 11.1%.