基于H∞滤波的异纤光电信号检测

针对纺织企业中异纤难以检测的问题,提出了一种采用单个绿色调制光源、三个硅光电池规则排列检测异纤和纱疵的方案,通过对硅光电池接收到的反射和透射信号进行对比,分析纱线颜色和直径的变化,判断纱线是否存在异纤和纱疵。并建立了数学模型,基于H∞滤波方法采用MATLAB软件进行了仿真实验。结果证明,该算法对纱线表面亮度信号检测和纱线直径信号检测的信号突变更加敏感,并可跟踪异色百分比的变化,所设计的异纤和纱疵检测方案切实可行,H∞滤波算法可以有效提高异色疵点和粗细节疵点的检测精度。     

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。     

Detection clustering analysis algorithm and system parameters study of the near-point multi-class foreign fiber

In this paper, we investigate a detection algorithm for foreign fiber during the processing of cotton textile. By collecting a large number of samples, we determine the color model and establish its characteristic parameters of a foreign fiber. We found foreign fibers of multiple types (classes) and proposed a classification–recognition algorithm based on clustering analysis. The maximum error of the studied recognition algorithm is 0.012, which meets the requirement to recognize foreign fibers. Through many experiments, the optimal parameters for the foreign fiber detection system were determined, and the fiber recognition rates for different types were obtained. The lowest recognition rate is 85%. This is sufficiently high to reject foreign fibers and reach the standards of the textile industry. Experimental results show that foreign fiber clustering analysis algorithm is feasible, and it not only improves the quality of foreign fiber detection significantly, but also has high theoretical value and practical value.     

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.     

氨纶包芯纱蠕变性能测试与分析

对大豆蛋白复合纤维、棉和涤纶纤维纺制的氨纶包芯纱的蠕变性能进行测试,基于纺织材料的黏弹性理论,使用四元素力学模型分析氨纶包芯纱的拉伸变形规律,并利用DPS数据处理系统,建立了氨纶包芯纱蠕变伸长的拟合方程,从本质上研究大豆蛋白/氨、棉/氨、涤/氨包芯纱的蠕变性能特征。结果表明:氨纶包芯纱外包纤维种类不同,其蠕变性能亦不同;四元素模型的理论分析结果比较接近实际测试值,即应用四元素模型可以较好地描述各种氨纶包芯纱的蠕变规律。     

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。     

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。     

使用异纤分检装置清除异性和沾色污染纤维

介绍了异纤污染和沾色污染的概况和危害,叙述了清棉异纤分检仪和异纤电子清纱器的检测原理和使用效果,分析了纺纱流程中异纤和沾色污染纤维清除点的设置和清除参数的选择。     

Influence of Friction Spinning Process Parameters on Spinnability of Pergularia/Cotton-Blended Yarns

In this study, spinnability of Pergularia daemia seed fiber (70%) and cotton fiber (30%) core/100% cotton fiber sheath DREF-3 core yarns of 74 tex were studied using different spinning parameters in order to understand their effect on yarn properties. Box-Behnken Design was used for the optimization of core ratio, drum speed, and suction pressure and to evaluate the effects and interactions of the process variables on the yarn properties at a constant opening roller speed of 12,000 rpm and delivery rate of 100 m/min. The effect of the core/sheath ratio on yarn quality index is significant. With an increase in the core/sheath ratio, yarn tenacity, and elongation decreases due to insufficient wrapper fibers in the yarn and yarn unevenness increases due to higher feed rate and draft at higher core ratio. An increase in the spinning drum speed increases the yarn quality index up to certain range and then decreases at higher speed due to damaging of fibers in the sheath and more number of hooks at the end of fibers. At a higher air suction pressure, yarn tenacity and the elongation at break increases which ultimately increases the yarn quality index. From the regression analysis, it is observed that the drum speed and suction pressure has no significant effect on yarn unevenness.     

环锭纺纱中加捻三角区内纤维受力分析

加捻三角区是成纱过程中的一个关键区域,其几何形态直接影响到三角区内纤维张力的分布进而决定纱线质量。在三角区的几何参数中,加捻点的水平偏移量越来越受到关注,并被认为是影响成纱质量的重要参数之一。针对此,本文利用纤维在三角区内的运动规律,给出具有任意偏移量的加捻三角区内纤维张力分布的理论模型。指出三角区加捻点处的纤维张力由纤维在前罗拉钳口处的速度、加捻点的输出速度、纤维在前罗拉钳口处的初始张力、纤维弹性模量、纤维横截面积和与中心纤维的夹角决定,为三角区优化设计提供理论参考。     

竹纤维混纺纱生产工艺技术探讨

为了探讨竹纤维混纺纱的生产工艺,根据竹纤维的弹性差、伸长大、强力低、比电阻高、静电大、可纺性能差等特点,从纤维性能和纺纱工艺参数等方面进行分析和研究,探讨了提高竹纤维混纺纱质量的一些关键技术措施.结果表明:竹纤维混纺纱有害纱疵少,条干均匀,强度好.     

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。     

Research on Sirospun yarn torque using airflow false twisting device

Yarn torque is one of the most important indexes of yarn quality, which is determined on the mechanical state of the constituent fibers and their configuration in the yarn. The fiber tension within a yarn was proposed to be the most influential factor governing the magnitude of yarn torque by Bennett and Postle. Therefore, the research on Sirospun yarn torque is investigated by analyzing the fiber tension at spinning triangle in this paper. Firstly, theoretical models of the fiber tension distributions at primary and final spinning triangles are presented, and corresponding residual torque within a yarn due to the fiber tension is given. The relationships between the yarn torque and the spinning triangle parameters are analyzed theoretically. Secondly, as an application of the proposed method, a modified Sirospun spinning system with an airflow false twisting device which can change spinning triangle parameters are investigated, and the properties of spun yarns produced by the modified system are evaluated and analyzed. It is shown that with the increasing airflow pressures, the Sirospun yarn shows a more and more uniform distribution of tensile and compressive stress within a yarn, and thus the yarn torque decreases correspondingly.     

提高精梳针织用纱质量的工艺探讨

精梳针织用纱质量以坯布质量好纱疵少为评价标准。选用原棉要控制成熟度、短绒率和有害疵点;精细清棉、完整梳理、选用有设备特性的高产梳棉机是减少纱疵的基础;精梳采用后退给棉方式及短给棉长度可提高梳理效率,使精梳落棉中含短绒率高而精梳条中含短绒率低;自调匀整并条机使熟条定量稳定、成纱号数恒定;细纱机后牵伸力的设定与成纱质量关键密切;控制好自动络筒机张力与速度、用好清纱器可有效去除10万m纱疵中的短粗节和长粗节。     

大豆蛋白纤维混纺纱混纺比与拉伸性能的关系

为了研究大豆蛋白纤维混纺纱的混纺比与拉伸性能的关系,对各种不同混纺比例的大豆蛋白纤维涤纶纤维混纺纱、大豆蛋白纤维棉纤维混纺纱的拉伸性做了测试分析,并与传统的简化模型做了对比.结果表明:大豆蛋白纤维棉纤维混纺纱的混纺比与强度之间的关系并不符合简化模型,主要是由于混纺纱中两种纤维的交互作用所产生,交互作用越大,差异越大;大豆蛋白纤维涤纶纤维混纺纱、大豆蛋白纤维棉纤维混纺纱的断裂强度和断裂功随混纺比的变化关系基本一致.     

混纺纱条不匀与组分纤维细度及其不匀的关系

对双组分纤维混纺时纤维细度及其不匀对成纱极限不匀的影响进行了分析,建立了双组分纤维混纺纱的极限不匀与各组分纤维细度及其不匀、混纺比之间的理论关系式。并用几种双组分纤维及其混纺纱的实例与所得出的理论关系式做了验证对比。     

应用聚类神经网络的异纤检测多类光源优化设计

为使电荷耦合元件（CCD）精确采集处理异纤图像并对多类异纤进行检测,提出了一种基于模糊聚类神经网络的异纤检测多类光源优化设计方法。通过分析CCD成像与入射光能量的关系,推导出多类异纤检测的光源量,建立了CCD靶面曝光量函数,确定光源的最佳检测位置,通过图像参数方程,分析CCD背景板图像的光线分布及平均灰度,通过模糊聚类分析,综合考虑输入值的全部信息建立了多类光源的模糊聚类神经网络,对光源进行优化设计。设计结果表明,最佳检测位置是异纤处于中心位置,在光源数量为10,两侧距离为3mm,神经网络的收敛误差均达到预期值,异纤检出率达到94.79%,符合企业异纤检测实际生产的要求。     

Strengths of Twisted Blend Fibrous Structures: Theoretical Prediction of the Hybrid Effects

Hybrid structures have been applied in many areas such as textiles and composites. However, the mechanisms giving rise to the advantages associated with fiber blending, presumably due to the interactions between constituents of different types, are still poorly understood. This work is an attempt to look into the internal interactions through theoretical analysis. A twisted structure (yarn) of two distinct fiber types with statistically distributed strengths is studied. It has been established in yarns of the single fiber type that the interaction via friction between fibers will lead to a substantial increase of fiber effectiveness, and consequently the yarn strength. Incorporating this concept into the present hybrid case makes it possible to more accurately predict the strength and its distribution for the blended yarn. Moreover, it is revealed in this study that the interaction between fibers prior to the initiation of yarn failure may be the most important factor which causes the so-called hybrid effects. Predictions of the hybrid effect are provided and the influences of relevant factors are discussed in this paper.

Although the present work is targeted at hybrid yarn structures, the conclusions drawn herein are in principle applicable to hybrid fiber composites as well.     

Tensile behavior of staple fiber yarns part II: model validation

The theoretical models of tensile behavior of staple fiber yarns derived in Part I of this work are compared and validated with experimental results. It is observed that the stress–strain curve of yarn always lies under the stress–strain curve of fiber. The well-known Gégauff’s theory is found to overestimate fiber stress utilization in yarn. The partial generalization of helical model by taking fiber orientation into account results in satisfactory agreement with the experimental results. Clearly, fiber orientation plays an important role in deciding the fiber stress utilization in yarns. The lower is the variability of fiber direction in relation to the corresponding helical direction of fibers, the higher is the fiber stress utilization in yarn.     

生物基锦纶56和锦纶66的结构与吸放湿性能评价

为系统分析生物基锦纶56与锦纶66的吸放湿性能,在标准状态下对不同规格纤维进行对比研究。测试了生物基锦纶56、锦纶66弹力丝及短纤维的吸湿、放湿和干燥特征曲线,并由此推导出4种纤维在标准状态下达到吸湿、放湿和干燥平衡过程中,回潮率或含水率对时间的回归方程,以及吸湿、放湿和干燥速率方程。结果表明:标准大气条件下,与锦纶66相比,生物基锦纶56的吸湿、放湿平衡回潮率大,吸湿、干燥速率大,初始放湿速率略小,但随着时间的延长,生物基锦纶56的放湿速率大于锦纶66;4种纤维的吸湿等温线均呈反S形,在高湿度环境下生物基锦纶56的干燥性优于锦纶 66,即生物基锦纶56具有较好的快干性能。