采用多项式拟合的细纱机双区与三区牵伸纤维分布对比

为探究牵伸倍数提高及牵伸区个数改变对成纱条干的影响,以9.7 tex和7.3 tex棉纱为例,分别采用QFA1528三罗拉双区牵伸细纱机和TH558四罗拉三区牵伸细纱机进行纺纱实验,采用切断称重法和Mat Lab多项式拟合方法对前牵伸区内纤维数量进行拟合计算,得到快速纤维和慢速纤维的分布曲线,对比分析2种牵伸方式前牵伸区内摩擦力界分布及纤维理论变速点的位置,从而探究牵伸方式对成纱质量的影响。结果表明:对于9.7 tex棉纱,双区牵伸使前区纤维理论变速点比三区牵伸细纱机前移,条干质量较好;对于7.3 tex棉纱,三区牵伸可使进入前牵伸区的须条结构得到优化,纱线综合质量提高。     

基于循环迭代法的牵伸区纤维运动仿真模拟

为进一步研究牵伸区纤维的运动,基于单纤维在牵伸区内受到的引导力与控制力,采用循环迭代法建立纤维变速模型,计算牵伸区不同压力分布下不同长度纤维的变速点,并得到牵伸区内纤维变速点分布以及各位置不同纤维(包括快速纤维、慢速纤维以及浮游纤维)的分布。结果表明：纤维的变速点位置与其自身长度有关,纤维长度越长,其变速点越靠近前罗拉钳口;在不考虑浮游区情况下,对于长度离散度较大的纤维须条,牵伸区内平稳、缓和的压力分布有利于纤维变速点的集中,但纤维变速点离前钳口较远;纤维长度长、离散度较小时,靠近前钳口增加附加压力有利于变速点的集中且其更加靠近前钳口。     

前牵伸区内纤维变速点分布对混纺纱成纱质量的影响

为探究细纱机前牵伸区内纤维的变速点分布与不同比例混纺纱线的成纱质量的关系,文章以纺R65/T35和T65/R35混纺纱在前区牵伸倍数为40、50、60为例,采用CCZ-X三罗拉双区牵伸细纱机进行实验,对比分析不同牵伸倍数下同一混纺纱纤维变速集中的位置,以及相同牵伸倍数下不同混纺纱的纤维变速集中的位置,从而探究牵伸区内纤维变速点分布对成纱质量的影响。结果表明,当牵伸倍数为50时,R65/T35和T65/R35在前牵伸区的纤维变速点更集中靠近前钳口,成纱条干更好;牵伸倍数为40倍时,T65/R35混纺纱的条干更优,牵伸倍数为50、60倍时,R65/T35混纺纱的条干更优。     

并条机“紧隔距重加压”的实践

罗拉牵伸的理论和实践指出,纤维的变速点分布的分散,特别是须条中短纤维变速位置不稳定,使输出须条中纤维头端产生较大的移距偏差,是造成附加不匀率的主要原因。原棉中短绒率愈高,或罗拉钳口间隔距愈大,这种附加的条干不匀率也愈大。为了改善输出须条的条干均匀度,应控制牵伸区的纤维运动,特别是要使短纤维的变速位置尽量靠近前钳口,变速点分     

超大牵伸条件下前牵伸区内纤维变速点分布对成纱质量的影响

为了探究超大牵伸条件下纤维变速点分布与成纱质量之间的关系,先以定量为16.0 g/5 m的熟条来纺制定量分别为3.54、4.32、5.51、6.20 g/10 m的粗纱,而后在含有四罗拉四皮圈的TH558型三区超大牵伸细纱机上分别以50、60、70、80倍的前区牵伸倍数来纺制5.8 tex的细纱,并测试不同前区牵伸倍数下的纤维变速点位置,对纤维变速点分布进行统计分析,从而探究前区牵伸倍数对纱线质量的影响。结果表明:当前区牵伸倍数为60倍时,纤维变速点分布更集中、稳定、前移,且纱线的各项性能较为理想;在一定范围内,随着前区牵伸倍数的增大,变速纤维集中位置变得分散、后移且不稳定,条干不匀增加,纱线质量变差。     

基于纤维变速点分布实验的成纱条干不匀研究

为探究大牵伸条件下,牵伸倍数的提高和牵伸分配对成纱条干的影响,提出变速点分布实验方法,通过纤维变速点分布的变化,分析成纱条干不匀。以9.7 tex棉纱为例,对比环锭细纱机与超大牵伸细纱机前区变速点分布曲线,在超大牵伸细纱机上以线密度1 000 tex粗纱分别纺制9.7、7.3、6.5 tex棉纱,并以9.7 tex棉纱为例,探讨不同牵伸倍数分配时,前区变速点分布曲线。结果表明:超大牵伸细纱机较环锭细纱机变速点分布更集中、稳定、前移,成纱条干更优;随牵伸倍数增大,变速点分布分散,成纱条干变差;纺9.7 tex棉纱,后区、中区牵伸为1.1、1.3时,前区变速点分布更集中前移,成纱条干最优。     

特殊外观结构赛络花式纱的后区牵伸及成纱结构分析

为开发新型花式纱,在细纱机上采用刻有凹槽的后罗拉上胶辊纺制赛络花式纱。分析了此花式纱用胶辊对后钳口须条的受力及成纱结构,在TH598J细纱机上采用切断称重法测得胶辊转动1周从中罗拉输出的须条的质量分布,分别得到正常胶辊和花式纱用胶辊输出须条的质量分布,并由牵伸倍数公式分别获得正常胶辊和花式纱用胶辊的后区牵伸变化曲线,同时对成纱线密度进行分析,从而探究此花式纱的成纱外观结构变化。结果表明:刻有凹槽的胶辊使得后区牵伸倍数由正常逐渐降为1再逐渐增大到正常,通过凹槽的这段须条对其前后一段须条的牵伸产生影响,使之牵伸倍数从正常开始减小,从而使成纱线密度也呈现增减变化,获得了一种特殊外观结构的赛络花式纱。     

细纱工序采用压力棒隔距块提高成纱质量的实践

在细纱前区采用压力棒隔距块后,压力棒把原有浮游纤维分成两个浮游区,牵伸区内中后摩擦力界得以加强,使一部分弯钩纤维被更好地牵伸伸直.使用压力棒隔距块后,在前区又形成了曲线牵伸形式,须条在压力棒下形成一段包围弧,从而加强了前区对纤维的控制,使纤维变速点分布集中而稳定地靠近钳口,有利于改善条干均匀度,提高成纱质量.     

动态牵伸过程中浮游纤维变速点分布模拟

为研究牵伸条件的变化对牵伸过程的影响,通过建立动态牵伸模型,仿真浮游纤维在动态牵伸过程中受到摩擦力作用的加速过程,得到动态牵伸过程中浮游纤维变速点分布。纤维的牵伸过程被细化为后纤维、慢浮游纤维、快浮游纤维和前纤维4种纤维运动状态变化的过程。通过记录纤维在牵伸过程中速度和位置的变化,计算得到纤维保持每种状态的时间。模拟过程中,通过获取纤维在牵伸过程中速度和位置的变化,得到每根纤维在牵伸区内分别维持4种运动状态的时间,从而建立动态的牵伸模型。此外,通过确定浮游纤维与快速纤维和慢速纤维相互接触的长度,计算浮游纤维在动态牵伸过程中受到的控制力与引导力,模拟浮游纤维在动态牵伸过程中的加速过程。同时计算简单罗拉牵伸的摩擦力界分布,通过改变牵伸模型的牵伸倍数和纤维长度,模拟不同牵伸条件下浮游纤维变速点分布。结果表明：仿真得到的变速点分布近似于正态分布,与实际牵伸过程中变速点分布形态接近;牵伸倍数越大,纤维的长度越长,变速点分布越接近前罗拉,并且变速点分布范围越小。     

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。     

Research on fiber distribution in front draft zone of super high draft ring spinning based on cut-middles method

A super draft ring spinning machine was designed to spin high-count cotton yarns. It was equipped with four-line draft system (FLDS) and four aprons. For yarns spun on FLDS, it often occurs that yarn unevenness increased compared with three-line draft system (TLDS). In the paper, by cut-middles method, the fiber distribution in front draft zone of FLDS draft system was studied, and corresponding yarn qualities were analyzed. First, comparison analysis of yarn quality between FLDS and TLDS was presented. Cotton yarns of 9.7 and 7.3 tex were spun by TLDS and FLDS ring spinning machine, respectively. The results shows that for 9.7 tex cotton yarn, slower fibers in yarns spun on FLDS are more than that in yarns spun on TLDS. For FLDS, the friction field at the back of front draft zone is stronger, which improves yarn evenness. However, for 7.3 tex cotton yarn, accelerated point of fibers on FLDS is nearer to nipper bite of front roller than that on TLDS. Thus, evenness of yarns spun on FLDS is better. Then, 4.9 tex cotton yarn was taken as an example, and they were spun by four kinds of draft distributions on FLDS. The results indicate that for 4.9 tex cotton yarns spun by 64.1 × 1.60 × 1.15, slower fibers at the back of front draft zone are mostly found. And accelerated point of fibers is nearest to nipper bite of front roller. Therefore, 4.9 tex cotton yarns spun by 64.1 × 1.60 × 1.15 have best yarn evenness.     

基于数控耦合牵伸理论的色纺技术及其制品配色花型分布控制研究

适应色纺纱线个性化、高档化的市场需求,开发一种基于数控耦合牵伸理论的色纺技术。其技术关键在于两组合后罗拉由两个伺服电机驱动,与中罗拉形成相互独自的两个后牵伸区。通过调节伺服电机速度控制两根粗纱随机且相互耦合的牵伸比,在前罗拉钳口处形成具有等线密度的色纺段彩纱。分析了双组份耦合牵伸的基本原理,推导了其配色花型分布控制的基本方程,用实验验证了等线密度段彩纱随机性花型的可设计性与再现性。     

阻尼牵伸纺纱技术及其对成纱质量的影响

从纺纱牵伸装置结构和牵伸机制方面,阐述了新型环锭纺阻尼牵伸系统提高成纱质量的原理及应用效果。分别采用传统环锭纺和阻尼牵伸纺技术纺制羊毛/羊绒混纺纱,并对成纱均匀度和强力指标进行测试,采用差异率进行对比分析。结果表明:阻尼牵伸系统可以显著改善成纱条干均匀度,降低粗节、细节、棉结、毛羽量等指标,其中粗节(+50%)数量降低41.0%,最为显著;成纱的强力、断裂伸长率和断裂功等力学指标有所提高,其中断裂伸长率提高23.1%,阻尼牵伸技术对提高毛纱的成纱质量具有良好的效果。     

基于纤维长度分布的浮游纤维变速仿真

采用非参数核密度估计的方法获得纤维长度分布的密度函数,随机生成牵伸区纤维分布样本。利用多项式回归拟合出JF型双短胶圈环锭细纱牵伸装置的纵向摩擦力界分布函数,结合纤维变速的数学模型,采用计算机方法模拟出JF型牵伸装置在纤维等长均匀分布和核密度估计分布下的变速点分布形态的直方图。结果表明：等长分布纤维的变速点高度集中于前钳口;核密度估计分布纤维变速点分度离散,近似于正态分布,表明纤维尾端离开后钳口即会有变速可能,可见核密度估计分布下纤维变速点分布的模拟结果更接近于真实情况。此方法可用于对实际牵伸工艺和牵伸机构的优化和预测。     

金属纤维在常规纺纱设备上的牵切实践

研究了用作防静电织物的金属纤维在常规纺纱设备上的牵切方法和工艺,重点是在常规纺纱设备(A272C)上将连续的不锈钢纤维持续地扯断成单根纤维且不使条子整个地切断的试验。经改进的并条机牵切的不锈钢纤维与常规纤维并合后可正常纺纱,所纺导电纱质量较好。     

Research on yarn qualities modified by mechanical false-twisting device

Abstract

In the ring-spinning process, the area between the front roller nip and twisting point is spinning triangle, and its geometry influences the fiber tension distribution in the spinning triangle directly and determines the properties of spun yarns. Therefore, in the paper, one kind of mechanical false-twisting device was introduced on the ring spinning, which can affect the twist propagation and change the spinning triangle geometry actively. First, the modification of the false-twisting device on the DTM129 ring-spinning frame was introduced. Taking the medium cotton yarn spinning as an example, corresponding ring yarn, Sirospun yarn, compact yarn were spun on the modified spinning frame under different designed twist factors, and the applicability of the false-twisting device on different spinning method was discussed. It is shown that comparing with the common yarn, the Hairiness and Strength of the modified yarns are all improved, and the effect of false-twisting device on yarn qualities is more effective for the low-twist yarn. Comparing with the ring spinning, the improvement degree of the modified compact spinning is a little smaller. Then, the long-staple cotton ring yarn, polyester and medium cotton blend ring yarn, polyester ring yarn were spun on the modified spinning frame under different designed twist factors, and the applicability of the false-twisting device on different fibers was discussed. It is shown that the influence of the false-twisting device on the long-staple cotton yarn and polyester yarn is little. That is, the false-twisting device given in the paper would be more applicable on the short fiber spinning under the low designed twist factor.     

等线密度精确段彩纺成纱性能分析

段彩纱属于花式纱的一种,它利用不同原料、不同颜色纤维组合纺纱,使不同纱段具有不同的色彩、性能。同轴后罗拉牵伸机构可纺制等线密度段彩纱,但过渡段经前区牵伸变长,达6cm以上。采用新开发的同轴中罗拉牵伸机构结合气流集聚方法可纺制过渡段不超过2cm的等线密度段彩纱。主要分析分段时间对纺出纱线的条干均匀度、强力、毛羽指数的影响,使得这种纱线和工艺能更好地被应用在实际生产中。     

赛络纺棉/毛段彩纱结构及其性能

针对环锭纺三罗拉和四罗拉法所纺段彩纱条干不匀的结果问题,采用同轴双后罗拉2组粗纱同锭位藕合等量喂入的方法纺制等线密度赛络纺棉/毛段彩纱,并对成纱的结构及性能进行了分析。纱线的纵向观测结果表明棉与毛的质量比差异越大,分段时间越长,纱线的段彩效果越明显;截面观测结果表明棉和毛纤维在纱中互相压紧并包缠形成类似于太极阴阳鱼的结构;分段中棉与毛质量比差异及纺纱分段时间增加时,纱线的断裂强度变小,CV值变大,但对有害毛羽数量影响不大。该纺纱方法使用天然的棉和毛纤维,既丰富了现有花式纱线的产品种类,也在对细纱机进行简单改装的条件下制得股线风格的毛型感段彩纱,符合绿色低碳循环发展的趋势。     

Effect of accelerated point distribution on sliver irregularity. Part Ι: characterization of accelerated point distribution

This paper introduces a new approach to characterize the accelerated point distribution in roller drafting. The approach uses 2-parameter Weibull distribution and Log-normal distribution to estimate the probability density function of the fiber accelerated point by including the influence of draft ratio and ratch, as well as fiber lengths. The coefficient of variation (CV) of accelerated points is then derived by employing conditional probability. The model was applied to a group of simulated data from literature and newly obtained experimental data of accelerated point distribution. The CV of the fiber accelerated points was compared with the CV from other published accelerated point distributions and the data derived from measurements of sliver irregularity. The model based on Log-normal distribution was proved to adequately characterize the probability density function of the fiber accelerated point. The accelerated point distribution would be a plausible variable to be utilized in the optimization of the draft settings.