Abstract: Vortex spinning is a new spinning technology that adopts the swirling airflow formed inside the nozzle to form the yarn which is composed of a core made of parallel untwisted fibers and the spiral sheath fibers wrapping around the core fibers. This special two-layered structure makes vortex spinning especially suitable for spinning core-spun yarns. The core-spun yarn containing a metal wire fabricated by vortex spinning is a new type of conductive yarn. However, in the process of vortex spinning, the high-speed swirling airflow will make a portion of fibers overcome the twisting force to become lost fibers, which will reduce the amount of fiber on the yarn surface. This will result in the exposure of the metal wire on the yarn surface, which will deteriorate the yarn quality. Therefore, it is of great significance to design the vortex spinning nozzle with reduced lost fibers.
In order to reduce the amount of lost fibers during the spinning process of core-spun yarn containing a metal wire, the vortex spinning nozzle is designed and manufactured. According to the spinning principle, a vortex spinning nozzle with several air suction holes arranged on the wall of the yarn passage through the spindle is designed. The modified spindle is composed of the main body, air suction pipe and end cover. The main body and end cover of the spindle are manufactured by casting molding method with epoxy resin as the material. For the manufacture of air suction pipe, a micro twist drill is used to drill holes on the wall of the copper pipe with an outer diameter of 1.6 mm, an inner diameter of 1.3 mm, and a length of 73 mm. In order to study the effect of the suction airflow and different structural parameters of the suction holes on the fiber loss and yarn breaking tenacity, five air suction pipes with different parameters are designed and manufactured for the spinning experiments with the spindle without suction holes taken as the experimental control group. The method of measuring yarn linear density is used to indirectly characterize the amount of lost fibers under different working conditions. On this basis, the Minitab software is used to statistically analyze the measurement results with 95% confidence intervals. The Grubbs criterion is used to test whether there are abnormal values in the data. ANOVA is used to study the effect of suction hole diameter and axial length of air suction region on the fiber loss during the spinning process and yarn breaking tenacity. The results prove that compared with the traditional nozzle, adding air suction holes on the the wall of the yarn passage through the spindle can effectively reduce the fiber loss during the spinning process and increase the yarn breaking tenacity. The effect of hole diameter in the range between 0.2 mm and 0.4 mm on the amount of lost fibers is found to be insignificant, while the core-spun yarn exhibits highest tenacity at the hole diameter of 0.2 mm. As the axial length of air suction region changes from 25 mm to 34 mm, there is no significant effect on the fiber loss and breaking tenacity of yarn.
The results of this study can provide a new idea for the design of air-jet vortex spinning nozzle device.

Key words: vortex spinning, air suction, core-spun yarn containing a metal wire, lost fibers, breaking tenacity

摘要： 金属丝包芯纱作为一种新型的导电纱线,具有广阔的应用前景。为了减少金属丝包芯纱成纱过程中的纤维损失,设计了一种在引纱通道壁面上设有气流抽吸孔的喷气涡流纺空心锭装置,通过纺纱试验,研究了抽吸孔直径和抽吸区长度对纺纱过程中落纤量和纱线断裂强度的影响。结果表明:在纺锭引纱通道壁面上设置抽吸孔有利于减少成纱过程中的纤维损失,提高成纱断裂强度;抽吸孔直径在0.2～0.4 mm范围内变化时,抽吸孔直径对纤维损失量的影响并不显著,而包芯纱断裂强度在直径为0.2 mm时最高;当抽吸区长度从25 mm增加至34 mm时,对纤维损失和成纱断裂强度均无显著影响。研究结果可为喷气涡流纺纱喷嘴装置的设计提供了一种新思路。

关键词: 喷气涡流纺, 负压抽吸, 金属丝包芯纱, 落纤, 断裂强度