Experimental study on the formation of core-spun yarn manufactured on a modified vortex spinning system

Abstract

Aiming at achieving online monitoring of the yarn formation process of vortex spinning, this paper presents a direct observation method that adopts a charge-coupled device camera fitted with an industrial endoscope that can reach into the nozzle chamber through a small hole drilled on the nozzle wall. Local pressure distortion in the vortex chamber due to the mounting of the observation apparatus was found experimentally. However, the yarn quality was not significantly affected, indicating that the proposed method has the potential to find industrial applications. Based on this method, the formation process of core-spun yarn containing a copper wire manufactured on a modified vortex spinning system is successfully observed. The results show that the core wire is covered by the main strand (core fibers), while the main strand is false-twisted during the yarn formation process. The level of false twist in the main strand fluctuates with time. The level of false twist in the main strand is higher in the upstream region, while it gradually decreases toward the downstream. Mostly, the trailing ends of some fibers are separated from the main strand and expand over the spindle tip to wrap around both the core fibers and core wire to form wrapper fibers in the yarn, while the leading ends of a smaller number of fibers are separated to form wrapper-wild fibers in the yarn. The proposed method can be extended to the study of fiber movement in confined spaces in other textile manufacturing processes.

Design of the Nozzle for Producing Vortex Core-Spun Yarns

“…Therefore, a filament feeding device with an extremely complex structure is needed for controlling the tension [20]. Pei Z, et al reported a design of the nozzle for producing vortex core-spun yarns [5,21]. In their design, a filament feeding orifice is provided through the fiber guiding member at the nozzle inlet instead of the guiding needle.…”

“…Besides, in the nozzle of traditional design, some fibers are pulled out of the fiber strand under the action of the tangential and axial components of the forces from the swirling airflow inside the nozzle chamber and the annular cavity between the spindle and nozzle wall. These fibers become the lost fibers the two ends of which are both in the free state and are then expelled out of the nozzle, which can lead to the deterioration of the yarn evenness [21,22]. Therefore, in order to obtain vortex core-spun yarns with uniform staple fiber sheath around the core filament, designing the nozzle with a low amount of lost fibers is needed.…”

Effect of selected production parameters on yarn evenness, imperfections and tensile properties of core spun vortex yarns

“…, 2019). Pei and He (2019) observed a core-spun yarn formation process containing a copper wire produced on a modified vortex spinning system. It was carefully observed that core wire was covered by the main strand, while the main strand is false twisted during the yarn formation process.…”

“…It was understood from scanning electron micrographs that the copper wire locates in the core region and tightly wrapped by the helical staple fibres of the outer layer in the core-spun yarn . Pei and He (2019) observed a core-spun yarn formation process containing a copper wire produced on a modified vortex spinning system. It was carefully observed that core wire was covered by the main strand, while the main strand is false twisted during the yarn formation process.…”

Fiber movement during twisting in air vortex spinning

“…2 developed a three-dimensional numerical model of airflow within a vortex spinning nozzle and a free-end fiber, utilized structured hexahedral meshes and unstructured tetrahedral structures to delineate the computational region of the airflow and verified the importance of dynamic numerical simulation in solving the unobservable dynamic torsion process by taking into account the physical properties of the fiber. Pei and He 3 utilized a charge-coupled device in conjunction with an industrial endoscope to observe the formation process of a copper wire core yarn and theoretically demonstrated that this method can be applied to other textile manufacturing processes. Smith and Roberts 4 studied the motion of fibers in a two-dimensional accelerated laminar flow.…”