纱条中纤维排列状态与纱条不匀的关系

为研究短纤维纱条中纤维的排列状态与纱条截面纤维根数分布不匀的关系,采用几何概率方法建立了等分区间内纤维左头端数分布与纱条截面纤维根数的期望之间的数学模型,并定义了表征纱条中纤维排列状态的参数。运用蒙特卡罗方法模拟了纱条截面根数不匀随排列参数变化的关系曲线。结果表明:短纤维纱条截面纤维根数的CV值与纱条中短纤维排列参数呈负线性关系,与纤维长度分布和模拟区间大小的划分无关;且当排列参数接近1时,即纤维左头端数在所划分区间中为固定值时,纱条截面纤维根数不匀最低,而当排列参数趋向于0时,即纤维左头端数在所划分区间中呈泊松分布时则不匀最大。     

基于纤维排列参数的纱线不匀预测

在某一纱条结构假设下,提出一种新的纱线细度不匀模型——纤维通道重排假构模型,并给出了既反映纱条截面纤维根数,也反映纱条纤维长度的纱条不匀程度的表征参数——纤维通道内间距。然后利用Martindale极限不匀率公式的原理,进一步给出这个模型的特征分析和各个参数之间的统计分析;最后在实验数据分析的基础上得到了预测的经验公式,并在已知纤维长度参数、纱线截面纤维根数的情况下,预测了纱线的条干不匀,预测结果的精度较高。     

环锭纱截面纤维根数与强力预测模型

推导了环锭纱截面纤维根数的计算公式,并用实际生产中常用、有代表性的20种纯棉环锭纱截面纤维根数实测数据进行修正,从而得到精度较高的纱线截面纤维根数计算公式,使用时把纱线特数、捻度和纤维分特数代入公式即可,既实用又方便.在此基础上,建立环锭纱强力预测模型.以实际生产中常用20种环锭纱的特数、捻度和强力数据平均值为依据,推导出纱线特数和捻度对纱线强力的修正函数,以此修正得到强力预测模型.使用此预测模型时只需代入纤维分特数、纤维强力、纱线特数和纱线捻度即可计算出纱线强力.     

棉纱线细度不匀特性的分析

为深入研究纱线细度不匀问题,依据纤维通道重排假构模型和纱线细度不匀的经验预报公式对棉纱线细度不匀的预报影响因数进行分析。将纤维有效长度改为平均长度,引入纤维线密度和纱线线密度因数改进了纱线细度不匀的经验预报公式。对改进后的经验预报公式进行分析,得到了纱线纤维通道数与纱条截面纤维根数的倍率、纱线线密度、纤维长度、线密度及不匀等参数对棉纱线条干不匀的影响规律。随着纤维细度变异系数的增大、纤维线密度的增大、纱线线密度的减小、纤维通道数与纤维根数倍率的减小、纤维平均长度的减小,棉纱线条干不匀增大,研究结果与实际生产相一致,对棉纱线生产质量的控制和提高具有参考作用。     

绢棉混纺紧密纱线的性能及结构研究

探索了绢棉混纺紧密纱线中纤维的转移和分布规律。试验得出绢棉混纺紧密纱毛羽少，强力和条十改善，纱线光洁紧密，纤维排列整齐。混纺纱线中绢丝纤维向纱芯的转移趋势不明显，绢与棉纤维较为随机地分散在纱线中。     

基于数字单元法的三维正交织物微观几何结构建模

为了反映织物内部纱线的空间构型和微观几何结构,针对在织物建模过程中,因忽略纤维间的相互作用而引起的纱线截面形状变化的问题,基于数字单元法理论,提出了一种计算纤维间摩擦力的方法。通过纱线纤维化离散,用数值模拟和仿真方法模拟三维正交织物成型过程,建立了5种精度递进的微观几何结构数值模型。5种模型中的每根纱线分别由4、7、12、19和37根数字纤维表征。研究结果表明:随着纱线纤维化离散程度的提高,仿真时间延长,织物厚度减小,纤维体积分数增大,节点平均作用力下降速度变缓,势能变小;当每根纱线由19根数字纤维组成时,所建织物的微观几何结构数值模型与真实织物样本在显微镜下的内部切片图像较为吻合。     

生条中纤维左头端的分布

为进一步探究纱条中纤维的分布规律,模拟纱条中纤维的排列情况,对纤维左头端沿纱条轴向服从均匀分布的假设进行实验验证。通过示踪纤维的方法测定若干给定长度的生条片段中染色纤维的左头端数,并利用χ~2拟合检验法对所测数据进行检验。结果表明:生条中纤维左头端沿生条轴向服从均匀分布的假设是合理的;通过改变染色纤维的几何特征、种类及所取生条的片段长度考察了对纤维左头端数的影响,证明了所取生条的片段长度对纤维左头端沿生条轴向服从均匀分布的结论没有显著影响,最终为预测纱条的性能提供了基础。     

第五讲 纱条的极限不匀率和不匀指数

由纤维随机排列所产生的纱条不匀,是现代纺纱方法所必然引起的纱条基本不匀之一。我们先来分析形成完全均匀纱条的必要条件。为了阐述简易起见,可先假定组成纱条的各根纤维平行伸直并具有相同的截面厚度;在这样情况下,组成一条完全均匀纱条的条件,就只是要求在纱条的各截面点上,具有相等数量的纤维根数;可以看出,这个要求达到与否将取决于纤维在纱条中的排列情况,或更确切地可看作是纤维端的排列与联结问题。要求纱条每一截面点上具有     

Modal／Wool混纺精纺纱的实践

1 使用原料情况 纤维细度是设计毛纱截面纤维根数、决定产品手感和毛纱条干均匀度最重要的品质参数，而细度CV值对毛纱线强度和仲长率有直接关系，     

羊毛防缩处理后对纱线CV值的影响

根据显微镜下的观察,羊毛防缩处理后,部分鳞片已被剥除,经过实际测量后,发现羊毛纤维的细度变细。在纺同支数毛纱时,防缩处理后的纱线截面根数增多,而截面根数又影响着纱线的CV值。通过分析试验数据,找出羊毛在防缩处理前后,同支数的纱线在CV值上存在的关系,采用数理统计上的一元线性回归方程分析得出,毛条防缩处理后的纱线CV值是未防缩处理纱线CV值的0.935倍+0.6,该结论对实际生产质量的控制具有指导意义。     

A new approach to theoretical yarn unevenness: a binomial distribution model

For many decades, Martindale’s theory on yarn unevenness has been widely used as a reference for staple yarn production and its quality control. With the yarn count becoming higher and higher and with the decrease in the yarn irregularity, the index of irregularity (I), defined on the basis of Martindale’s limit yarn unevenness, could not be used as a fully effective yardstick for evaluating the yarn unevenness caused by a specific spinning process. This approach, under some plausible assumptions, constructs a new model with a binomial probability distribution that describes the status of the fiber array in a yarn. The analysis of the model is done with the simulation of the parameters and the calculation of cotton ring‐spun yarns is conducted. A newly defined parameter, δ, proves to be valid for evaluating the change in the number of fibers in a cross‐section of the yarn. This parameter, which describes the variation in the number of fibers, can be used as a fiber alignment index in assessing the yarn irregularity in terms of the change in the number of fibers in its cross‐section. The new model can serve as a semi‐empirical method for forecasting the yarn unevenness.     

Geometry of fiber distribution in Marl yarn using the computational method

In this research, the structure of a type of bi-component composite yarns so called Marl yarn was studied. Fibers packing density factors within the yarn cross section as well as the effect of twisting on the resultant yarn were investigated. Samples of Marl acrylic yarns were provided using different twisting levels. Images of the cross sections of the produced yarn were obtained using the transverse sectioning method. The images were captured using the optical microscopy. The prepared images of the yarn cross section were then analyzed using image processing methods. In the first stage, yarn central coordinates and radiuses were calculated. In order to investigate the uniformity of fibers distribution and packing density within the yarn cross section, the fiber distances from the yarn center within the small radial and polar elements were calculated and the coefficient of variations (CV %) was determined. The maximum value of the fibers packing density was determined. The results showed that the fibers were mostly concentrated within the central region of the yarn; this was followed by the decrease in the fibers packing density while moving into the yarn’s outer layers. It was also concluded that increasing the intensity of the applied twist would result in higher fibers packing as well as the decrease in the yarn radius.     

新型全聚赛络混纺纱的成纱质量

为研究新型全聚赛络混纺纱成纱性能,采用一根5.0g／10m 精梳棉粗纱与另一根3.4g／10m涤纶粗纱在细纱工序进行全聚赛络混纺,纺出4种细度的棉／4 涤（60/40）新型全聚赛络混纺纱,并与单根混纺粗纱喂入所纺出的纱进行成纱质量对比;运用哈氏切片器,切取8种混纺纱线样本,在MOTTC B1型显微镜下观察纤维的分布状况,结合汉密尔顿指数分析方法,得到每种混纺纱内纤维的分布规律及内外转移趋势。结果表明：新型全聚赛络混纺纱的单纱条干CV值、断裂强力明显优于环锭混纺纱,且毛羽少;从单纱截面图得出,新型混纺纱中涤纶向纱芯转移呈现棉包覆涤纶的趋势,而环锭纺混纺纱中涤纶分布比较随机。     

段染纱横编织物花纹预测

为方便快捷地预测出给定段染纱编织的横编织物所形成的花纹形状,对段染纱色段的分布特征和横编织物的编织方式进行分析,探讨了段染纱色段在横编织物中的分布规律,确定其可用三角波函数来模拟。并用MatLab 语言编程模拟出给定段染纱编织的横编织物花纹,预测结果与编织实样有很好的一致性。研究结果表明：段染纱色段分布特征结合横编的往返编织方式,可在织物上形成多变的花纹,花纹形状与段染纱色段循环长度和织物横列用纱长度密切相关;用MatLab 程序可简便地实现花纹的预测,生产中可通过改变编织针数来获得所需的花纹,也可根据花纹的需要来选用或设计段染纱。     

芳砜纶纤维原料对其成纱及织物性能的影响

研究了芳砜纶纤维纺纱中,纤维长度对成纱性能影响的规律。采用不同长度的芳砜纶纤维在棉纺设备上进行纺纱对比,并对不同长度芳砜纶纤维纱织物的性能进行对比得出:在纱支一定时,芳砜纶纱及织物的拉伸性能随纤维长度增加而增加;纤维超过一定长度后拉伸性能下降,成纱毛羽则是先减少后增加。成纱条干在一定的纤维长度范围内,变化不大,纤维长度过长,则成纱条干明显恶化。芳砜纶织物的撕破性能变化与成纱拉伸性变化趋势类似。芳砜纶成品性能最佳时纤维长度为52 mm。     

基于临界滑脱长度的短纤纱断裂强力计算

为得到一种更加合理的短纤纱断裂强力的近似计算方法,根据短纤纱结构的理想化假设和临界滑脱长度的概念,推导出短纤纱断裂过程中纤维临界滑脱长度的近似计算表达式以及发生断裂和滑脱的纤维对短纤纱断裂强力的实际贡献。鉴于短纤纱截面纤维根数的不匀,根据计算得到的临界滑脱长度采用纤维在短纤纱中随机排列的模拟对短纤纱断裂强力进行计算。通过纺制不同线密度下具有不同捻系数的粘胶纱与涤纶纱并测试其断裂强力对该计算方法进行验证。计算和验证结果表明：临界滑脱长度的计算值随着捻系数的增加而减小,且当捻系数增加时,短纤纱断裂强力的计算值随着捻系数的增加升高至最高值而后发生下降,这是与实测短纤纱强力值的变化趋势是一致的。     

喷气涡流纺羊绒/涤纶混纺纱纤维径向分布

为研究纤维规格对喷气涡流纺纱线中纤维径向分布的影响规律,将两种不同规格的羊绒纤维和同一棉型涤纶纤维分别以相同比例混纺,经喷气涡流纺纱机MVS861制备了两种羊绒/涤纶纤维混纺纱线。运用哈氏切片器切取两种混纺纱线的横截面样本,借助扫描电子显微镜观察并采集纱线样品横截面的纤维分布图,结合汉密尔顿指数分析法和Onion指数法分析,得到喷气涡流纺混纺纱中羊绒纤维和涤纶纤维在纱线横截面内的内外转移趋势和分布规律。结果表明,利用喷气涡流纺纱技术制得的羊绒/涤纶混纺纱线中,羊绒纤维因其初始模量更小、长度更长有向外转移趋势,初始模量更大、长度更短的涤纶纤维则有向内转移趋势;但混纺纱的最外层纤维由纤维含量和纤维规格共同决定。该结论可帮助纺制喷气涡流纺羊绒混纺纱时根据需要来选择纤维原料的规格。     

Simulation on fiber random arrangement in the yarn part II: joint effect of fiber length and fineness distribution

Simulation on fiber random arrangement in the yarn has been studied in our previous research, where only fiber length distribution was considered. In this study, fiber fineness distribution was also taken into account in order to study the joint effect of fiber length and fineness distribution on fiber arrangement in the yarn. Eight-millimeter term limit irregularity of simulated yarn can be re-expressed by calculating the irregularity of the total weight of fibers within each yarn subsection. It can be seen from the results that the calculated irregularities considering fiber fineness distribution are closer to tested values compared with those without considering fiber fineness distribution. Besides, when the variance of fiber fineness gets greater, the difference between the calculated values with and without considering fiber fineness distribution becomes more obvious. For fiber length, the effect of average fiber length on yarn limit irregularity is very little, while its distribution has no significant effect on yarn limit irregularity. The improved simulation on fiber random arrangement in the yarn is more reasonable and can be applied for the prediction of yarn qualities.