【作者】 卢雨正；

【导师】 高卫东；

【作者基本信息】 江南大学 ， 纺织工程， 2007， 博士

【摘要】 目前竹节纱实际生产中存在着两个主要问题:竹节纱织造断头率高和竹节纱织物表面竹节分布不匀,它们均与竹节参数的设计密切相关,为了解决这两个问题,本文分别利用数学力学模型方法以及图形图像学的方法加以研究。首先重点介绍了当前与竹节纱相关的理论研究以及生产实践的现状。对竹节纱进行了分类,着重比较了几种竹节纱加工装置的区别,对于本论文实验中所采用的ZJ-5型竹节纱装置进行了详细介绍。论文从竹节纱捻度分布的角度入手,构建了竹节纱捻度分布的数学力学模型,将纱线的扭转加捻过程模拟为普通杆件的扭转过程,得出竹节纱中捻度大小的分布规律。根据纱线的捻回守恒定理,推导出竹节纱中各个纱段捻度分布的计算公式,并结合实际生产中的各种情况分析了公式的适用范围,采用间接法对公式的正确性进行了验证。竹节纱强力影响因素的分析建立在捻度分布模型的基础上,通过实验发现,基纱较粗的竹节纱与基纱较细的竹节纱断裂位置的分布有差异,较粗的竹节纱竹节部分易成为强力弱环;较细的竹节纱,基纱部分易成为强力弱环;此外,当竹节长度短于纤维主体长度时,竹节部分的强力会有所增加。在设计开发竹节纱的过程中,要提高竹节纱的强力,要注意两个方面:一要避免较粗竹节纱的竹节部分捻度太低,二要控制较细竹节纱基纱部分的捻度不超过临界捻度。接下来论文提出了竹节纱织物表面竹节分布的均匀性的评价方法。借用图形图像学中的面积A_s以及质心P(x_m,y_m)作为评价指标,对竹节纱表面竹节分布的均匀性进行评价。先通过扫描仪随机采集多个竹节纱织物子样图像,利用时域与频域相结合的方法,将子样图像中的竹节部分与底纹部分分离开来,得到了反映竹节分布状况的二值化图像,竹节分布均匀性主要与各子样二值化图像中竹节所占面积A_s的CV值(变异系数)以及竹节分布的质心P与布面几何中心位置O的最大偏移距离D有关,子样图像间竹节数量差异越小,各子样图像间A_s的CV值就越小;子样图像内竹节分布越均匀,D也就越小。对于一般竹节纱织物而言,子样图像间A_s的CV值小于10%,D值小于图像整体大小的10%的情况下,可以认为该竹节纱织物竹节分布均匀。为了实现虚拟评价,缩短竹节纱织物产品的开发过程,文章利用模拟方法获得竹节纱织物的竹节分布效果图,结合均匀性评价方法分析了竹节纱织物生产过程中各个参数对于竹节分布均匀性的影响。分析结果显示,竹节纱比例较高时,竹节纱参数的变化对于竹节分布的影响较小,竹节的分布均较为均匀;当竹节纱比例较低时,竹节设计参数的影响较为显著,模糊循环竹节纱中各个纱段组合之间的竹节间隔的差异越小,则织物中竹节分布越趋向于均匀。更多还原

【Abstract】 Two problems about the manufacture of the slub-yarn are discussed in the paper. The high ratio of broken ends and the uneven slub distribution in the slub-yarn fabric are the two difficult problems during the slub-yarn fabric manufacture, and both of them are closely associated with the slub parameters. The mathematic model and the image analysis method were carried separately to solve the two problems.First, the theoretical investigation and the practice of the slub-yarn are concluded in this paper. The slub-yarn is classified in this paper, and the characters in variety of controlling devices are explained and compared deliberately. The slub controlling device ZJ-5, used in the paper for all the experiments, is introduced in detail.Second, a model for the twist distribution in the slub-yarn is built as a tool for the analysis of the slub-yarn strength. The twist process is simulated as the common bar retorting process, and then the law of the twist distribution in the slub-yarn is carried out after a series of reasonable hypothesis. The calculating formula for the twist in slub yarn is deduced based on the theory of the conversation of twist. The range of application of the formula is discussed through the analysis to some factors and the validity of the formula is testified based on an indirect method.The analysis of the influential factors to the slub-yarn strength is carried on the model mentioned above. The experiment results proved that the slub-yarn with different linear density would have different breaking position. The thicker slub-yarn is easy to break at the slub part, while the thinner slub-yarn breaks at the base yarn part, although the two kinds of slub-yarns have the similar twist distribution. On the other hand, the slub length will increase the strength of the slub parts when it is shorter than the fiber principal length. Two efficient methods are necessary to increase the strength of the slub-yarn during its designg: one is to increase the twist in the slub part for the thicker slub-yarn; the other is to adjust the twsit in base yarn under the critical twist for the thinner slub-yarn.Third, the evenness for the slub distribution is discussed. An assessment method for the slub distribution is advanced at first. The indices in the image analysis, the center of mass P(x_m,y_m ) and the area As is taken as the new indices to assess the slub distribution. Some image samples are prepared through the scanner for the assessment, and the time domain method and the frequency domain method are carried separately to extract the slub parts from the fabric shading to acquire the binary images from the sample images. The distribution evenness is related to the CV% (coefficient value) of A_s in the sample binary images and the excursion extent D of the center of mass P to the geometric center O. The even distribution would lead less CV% and less D. The CV value of A_s in different samples can not exceed 10% and the maximum of D can not reach the 10% of the sample size in a slub-yarn fabric with even slub distribution.The simulating method is carried to acquire the binary image based on the slub-yarn parameters and the weaving parameters, which helps to shorten the slub-yarn fabric designing process. The influential factors to the slub distribution are tested through the simulation. The test result proved that, the change of the slub-yarn parameters influence the slub distribution little with the high slub-yarn ratio; while to the fabric with littile slub-yarn ratio, the slub parameters is sensitive to the slub distribution, and the smaller difference between the slub lengths in the non-periodic slub-yarn will increase the slub distribution evenness.更多还原