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。     

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。     

纱线条干不匀的随机模拟

 纤维随机排列的描述是研究纱线不匀理论的关键。给定一个纤维长度分布,如果假设纤维头端在纱线长度方向服从均匀分布,便可以建立理想纱条中纤维排列的几何模型。采用Monte Carlo方法模拟了这个理想纱线截面纤维根数的变化。在纱线的几何模型中,还使用8毫米的检测区域模拟了电容式条干仪的检测结果。通过比较说明,在纤维随机排列的前提下,随着纱线支数的增大,纱线模拟检测 值必然按照某个规律增大,理想纱条的截面纤维根数渐近服从正态分布,纱线截面的纤维根数变异与模拟检测的区间上纤维量的变异相关性不够显著。纱线实测数据说明了模型的有效性。     

牵伸区浮游纤维动态行为的随机模拟

通过各种模拟手段得到牵伸区浮游纤维动态行为的规律是牵伸研究的重要内容之一。在考虑了牵伸纱条中纤维长度分布的情况下,利用前人提出的纤维变速点的抛物线密度函数族方法,模拟纱条在牵伸区变细曲线的随机状态,讨论了在不同纤维长度分布下以及不同牵伸工艺参数下,纱条变细曲线的模拟结果。给出在快速牵伸区和慢速牵伸区纤维比例的模拟曲线,给出了在已知长度分布下,牵伸纱条在前罗拉钳口下纱条截面纤维根数变异系数的模拟,此模拟结果与已有模拟结果相比具有良好的相关性,为实现牵伸后须条不匀的预测打下了基础。     

测定混纺纱条混和不匀的方法

测定混纺纱条混和不匀的方法,目前主要有如下几种: 一、显微观察法——即切片法该法是在纱条的截面上,以各种成分的纤维根数所占比例大小来反映其混和不匀.对混纺纱条作横截面的切片,根据各种纤维的截面形状不同(如截面形状相同,就根据其染色性能不一而使某种纤维染上一种特殊颜色后加以区分.详细介绍见后),在显微镜或投影仪下,可数出纱条各个截面的切片上各种纤维的根数,再用统计方法,分析各截面内各种纤维根数     

条混工艺参数对混合效果的影响

不同组分纤维在纱线内混合不匀会导致混纺纱的强度降低、强力不匀恶化、布面色差等瑕疵增加.为探究条混工艺参数对混纺纱条混合均匀度的影响,通过改进混合不匀指数(IBI)表征混合均匀度,并采用计算模拟纤维在条混时的运动情况,获取混合纱条中纤维的分布规律.讨论了不同并合根数、并合道数、排列方式、混纺比等条混工艺参数对纱条混合均匀...     

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.     

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     

第一讲 纱条不匀率的统计分析基础

一、纱条不匀率的意义 提高成纱品质的基本要素之一是改善纱条不匀问题。在每道纺纱过程的半制品和成品纱线中,总存在着纤维在纱条长度方向上的排列不均匀状态,这是引起纱条其他各种性能不匀的基本原因之一,如产生了纱条的拈度分布不匀和纱线强力及伸长率不匀等,后三者都是从属性的。因此要改善纱线的品质,就必须首先研究分析纱条中纤维的排列     

提高棉纱条干的技术措施

一、纱条不匀的内容与性质纱条不匀,就广义来说包括下列几项:1、纱条沿长度方向上单位长度的重量不匀率或称线密度不匀率。2、纱条外观直径或纱条截面投影的不匀率。3、纱条的捻回不匀。4、纱线强力及伸长不匀。有的把纱线色泽不匀亦作为内容之一。     

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.     

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。     

单须条分束纺纱线的结构特征

通过对单须条分束纺纱线的纵向和解捻后的外观特征以及截面形态的观察,讨论了纱线的结构,并与传统环锭纺纱线作了对比。结果表明,单须条分束纺纱线的外观毛羽相对传统环锭纱要少而短;纤维间缠绕紧密,整体外观较光滑密实;纤维间接触概率相对较高,这正好与其断裂强度和耐磨性高互为映证。与环锭纱相比,分束纺纱线的断裂强度和伸长率的变异系数较大,这与纱条不匀、粗细节和毛粒较多有关。     

喷气涡流纺纱线细节产生机制分析

通过数值计算对喷气涡流纺喷嘴内部流场衰减规律进行探讨。讨论加捻腔中纤维的受力情况及涡流作用下的运动状况;建立倒伏在空心锭上的纤维自由端绕空心锭旋转的临界角速度与进入纱尾的纤维头端长度、纤维半径等参数间的函数关系,以临界角速度作为衡量纤维头端是否被抽拔的依据,解释喷气涡流纺落纤、成纱细节产生的原因。临界角速度随进入纱尾纤维头端长度的增加而增大;纤维半径越大,临界角速度越小,在同一喷嘴气压下,半径大的纤维纺纱时落纤、成纱细节较多;增加喷嘴气压对成纱强力有利,超过某临界值落纤、成纱细节增加,对成纱质量不利;增加喷嘴内部负压,适当减小前罗拉与空心锭的距离可减少落纤、细节的产生。     

A study on the suitability of which yarn number to use for recycle polyester fiber

Recycling and reuse of materials is not new to the textile and apparel industry. Recycling refers to the breakdown of product into its raw materials in order for the raw material to be reclaimed and used in new products. The aim of the study is that the examining the usage of recycle polyester fiber (rPET) in different yarn count and blend ratio and so to determine which count and blend ratio is more suitable for rPET usage. For this aim, 24 yarns containing recycle polyester fiber, virgin polyester fiber and viscose fiber as raw material were obtained in different yarn counts which are Ne 10, Ne 20, Ne 30 and Ne 40, and in different blend ratios. Yarn diameter, density, shape (roundness), unevenness, imperfection, hairiness, and yarn tensile tests were applied to the obtained yarns. The findings obtained by experimental and statistical study show that rPET fiber has usually negative effects on the yarn properties in especially fine yarns due to physical and chemical deterioration caused by contaminants of during re-processing of recycle polyester fiber. Based on the findings it is revealed that the values of unevenness, imperfection, and density increase whereas the values of diameter, hairiness, and tensile decrease from coarse yarns to fine yarns. As a conclusion it is possible to say that rPET fiber is suitable for thick yarns which are especially Ne 10 and Ne 20 as pure and in all blend ratios, and rPET fiber is suitable if it is used in lower ratios than 65% for Ne 30 yarns, whereas it is suitable if it is used in lower ratios than 35% for Ne 40 yarns.     

Effects of fiber types and blend ratios on Murata Vortex yarn properties

Murata Vortex spinning (MVS) system is one of the unconventional systems for yarn manufacturing. It is suitable for spinning of 100% cotton fibers, synthetic fibers, and cotton/synthetic fiber blends which are 1 inch or more in length. The production ranges are between Ne 15-60. Vortex yarn and fabrics have low hairiness, clear appearance, high resistance to pilling and abrasion. In this study, the vortex yarns with Ne 30 are produced in different blend ratios in Murata Vortex Spinner using carded cotton, viscose, modal, silver-added polyester (Flexsil-D2?), polyester, and nylon 6.6 fibers. Vortex spun yarns are tested to determine the yarn properties which are diameter, density, roundness (shape), unevenness, imperfection, Uster hairiness (H), Zweigle hairiness, tenacity, and elongation. The study reveals that the fiber type has quite significant effects on yarn properties. In terms of structural properties, cotton is the most negative fiber while regenerated cellulosic fibers are the most positive. As modal, nylon and polyester fiber increase yarn strength, nylon and viscose fiber increase breaking elongation. Viscose and modal reduce unevenness, imperfection and hairiness while polyester and nylon exhibit more negative effect on these properties.     

生条中短纤维含量与成纱指标的相关性分析

为探索生条中短纤维含量对纱线指标的影响,更好地通过短纤维含量指标对纱线指标进行预测,通过在不同锡林刺辊速度条件下对棉纤维进行梳理,并采用相同的后序工艺进行纺纱,将生产的生条取样,借助USTERAFIS 测试仪检测纤维的长度分布,分别统计出10、12、14 和16 mm 以下4 种短纤维的含量,同时借助条干、毛羽和强力测试仪分别检测各种实验条件下生产纱线的条干、强力和毛羽等指标,最后使用SPSS 统计软件计算出4 种短纤维含量指标与成纱各指标之间的相关系数。结果表明：当梳理工艺变化时,生条中短纤维含量指标与条干部分指标有较高的正相关性,与成纱强力指标不存在显著的相关性,与毛羽指标甚至是负相关。     

The effect of mass irregularities of weft yarns on fabric surface protrusion

Fabric surface unevenness and defects are usually created by yarn irregularity and defects in weaving process. These unevenness and irregularities appear on fabric and affect various fabric properties. In order to investigate weft yarn mass irregularities on fabric surface unevenness and defects, various plain fabric samples were prepared in which they differ only in weft yarn mass irregularity. One of the effective factors on fabric surface unevenness is yarn protrusion in fabric structure. Yarn protrusion in fabric structure is influenced by yarn’s physical and mechanical properties and fabric structural characteristics. In this work, relationship between mass irregularities of weft yarn and fabric surface unevenness was investigated using angular power spectrum curve, a measure of yarn protrusion in fabric structures. The results showed a high significant correlation between these two parameters.     

全聚纺集聚区吸风槽型对成纱质量的影响

探讨全聚纺集聚区吸风插件上的吸风槽型对成纱质量的影响。选取八种不同截面尺寸的吸风槽型,分别纺制20S、40S、60S精梳纯棉纱,并对所纺纱线各项成纱性能指标包括毛羽、条干、强力进行测试。结果表明:当吸风槽截面尺寸大时,气流的横向集聚作用减弱,对纤维须条的集聚效果差,成纱质量较差;相同吸风槽对不同纱支成纱质量的作用不同:随着所纺纱线支数的提高,最优吸风槽的截面尺寸相应减小。