转杯纺并合效应模型的构建与解析

Model construction and analysis based on rotor spinning merging effect

针对转杯纺纱的并合效应还未有成熟的理论模型这一问题,基于转杯纺纱超前剥取的特征并通过对剥离点、转杯参考点和纤维喂入点的相对运动的图解描述,分析纤维流在凝聚槽内凝聚和剥取规律,从而构建出转杯纺并合效应的理论模型。结果表明:原始纤维层的形态特征不仅是由粗变细而且呈现阶梯式的特点,每个“阶梯”的长度就是输出小节的长度;在不考虑加捻的因素下,输出纱条上属于同一圈的纤维层以输出小节的长度为单位,在纱体中错落分布于并合层的更低层,直至这一圈的纤维层被完全剥取;并合数与转杯直径、纱线捻度成正相关关系,同时验证了并合数计算公式的正确性。

Objective Rotor spinning is one of the most mature and widely used spinning technologies among various new types of spinning practically used mass production.The research on the merging effect of rotor spinning is relatively less involved.Therefore,exploring the fiber agglomeration process in the rotor groove and the merging effect will contribute to clarify the spinning mechanism of rotor spinning,study the yarn structure of rotor spinning,and guide the development of new-type rotor spinning.Method According to the advanced motion characteristics of rotor spinning,it is assumed that the peeling point,rotor reference point and sliver feeding point coincide in the initial state,and the original fiber-layer exists.Without considering the factors of twisting,the ideal distribution shape of fiber-layer in the rotor groove caused by the relative movement between the peeling point,the reference point and the fiber feeding point at each stage,as well as the shape of the output yarn in the process,are derived in combination with the way(Fig.2).Based on the agglomeration process of whiskers,combined with the fiber supplement amount equal to the output of whiskers peeling,the number of layers of original fiber-layers can be obtained.By combining the original fiber-layer distribution characteristics with the merging effect model,the fiber-layer distribution characteristics of the output yarn can be obtained.Results The ideal distribution state of condensation whiskers in each representative stage was shown(Fig.2).The merging situation at any stage was obtained through inductive method.Among rotating cup reference point A,fiber filling point C and peeling point P,coincidence of any two of these three points was taken as a representative stage.The number of original fiber layers for each representative stage of the output yarn was calculated based on the input of the fiber equal to the output of the yarn,and the distribution pattern of the fiber layer of the output yarn was outlined.The distribution characteristics of the number of original fiber-layers in a peeling cycle were derived(Tab.1 and Fig.3).It was found that the morphological characteristics of the original fiber-layers not only changed from coarse to fine,but also showed the characteristics of steps.The width of each″step″was the length of the output yarn bar.The fiber layer of the output yarn was not simply a layer-by-layer superposition and collection,but the same circle of fiber-layer along the output direction of the yarn,taking the length of the output yarn bar as the unit,was scattered in the lower layer of the composite layer in the yarn body until this circle of fiber layer is completely peeled(Fig.5).By analyzing the merging effect model,the merging number was obtained,which was equal to the ratio of the number of fibers in the yarn section to the number of fibers in the average section of the fiber flow.The simulated results were validated against practical merging effect from experiments to verify the correctness of the model.Conclusion Based on the characteristics of advanced peeling of rotor spinning and the analysis of the law of fiber flow collecting and peeling in the rotor groove,a theoretical model of the merging effect of rotor spinning is constructed.The model deduces that the morphological characteristics of the original fiber-layer not only change from coarse to fine,but also show the characteristics of steps.The fiber-layer of the output yarn is not simply a layer-by-layer superposition and collection,but the same circle of fiber-layer taking the length of the output yarn bar as the unit,and it distributes in the lower layer in the yarn body until this circle of fiber-layer completely peeled.By using this model,the calculation formula of the merging number is derived,and the merging number has a positive correlation with the diameter of the rotor and the twist of the yarn.