Numerical Simulation of Fiber Motion in the Condensing Zone of Lateral Compact Spinning with Pneumatic Groove

Lateral compact spinning with pneumatic groove is a spinning process to gather fibers by common actions of airflow and mechanical forces. Compared with ring spinning, it can more effectively reduce yarn hairiness and enhance yarn strength. However, fiber motion in the agglomeration area is complex. And, it is important to establish a new fiber model to accurately describing the fiber motion. The objectives of this research were to create a new fiber model to simulate the agglomeration process, to analyze yarn properties of the lateral compact spinning with pneumatic groove, and to compare with other spinning yarns through a series of tests. The new fiber model was based on the finite element method implemented in MATLAB and was to show the fiber motion during the agglomeration area. The simulation generated results were close to the real motion of fibers in spinning. In the lateral compact spinning with pneumatic groove, fiber bundle through the agglomeration area can be gathered, and the output of the fiber bundle was nearly to cylinder before yarn twisted. The experiments demonstrated that the lateral compact spinning with pneumatic groove can improve the yarn properties: increase the yarn twist, enhance the yarn strength, and reduce the yarn hairiness.

Effect of position of the fiber transport channel on fiber motion in the high-speed rotor

The task of the fiber transport channel (FTC) is to transport the fibers from the carding roller to the rotor. Its geometric position in the spinning machine has a strong influence on the characteristics of the airflow field and the trajectory of the fiber motion in both the rotor and the FTC. In this paper, a three-dimensional pumping rotor spinning channel model was established using ANSYS-ICEM-CFD software with three different positions of the FTC (positions a–c). Further, the simulations of air distribution were performed using Fluent software. In addition, the discrete phase model was used to fit the fiber motion trajectory in the rotor. The simulation results showed that among the three types of FTC, position b is the optimal condition. The gradients of airflow velocity in the channel at position b were greater than those of the other two positions, which is conducive to straightening of the fiber.

A FRACTAL TWO-PHASE FLOW MODEL FOR THE FIBER MOTION IN A POLYMER FILLING PROCESS

This paper suggests a fractal two-phase fluid model for the polymer melt filling process to deal effectively with the unsmooth front interface. An infinitesimal fluid element model in a fractal space is proposed to establish the governing equations according to the conservation laws in fluid mechanics, the fractal divergence and fractal Laplace operator are defined. The unsmooth interface is solved numerically, and fibers’ motion properties on the interface are also elucidated. Moreover, the distribution of fibers on the interface at different stages shows the fractal property of the fibers’ motion. However, the motion of fibers is affected by the flow of macroscopic polymer melt, and the fiber orientation in the interface shows a certain statistical regularity. Based on the characters of fiber orientation, the fractal interface can be used for the optimal design of the polymer melt filling process.

Fiber motion model based on yarn-forming mechanism in airflow

With the development of the textile industry, requirements relating to the quality of spinning of fibers to form yarn are becoming increasingly stringent. This paper analyzes the force of fibers in airflow to develop a drafting model and a twisted structural model of airflow, and numerically simulates the internal flow field of the drafting and twisting structures to obtain the optimal parameters for the model and nozzle. The structure is designed to improve the spinnability of different fibers. A fluid–solid coupling simulation is used to analyze the movement of fibers in the drafting channel, and parameters of the model are analyzed and optimized. The proposed model provides theoretical support for improving the speed and quality of spinning.

A study on fiber motion in the drafting zone and hook removal

In this study, the hook removal of four types of hooks during the drafting process has been investigated, and the theory of fiber straightening was further improved by analyzing the relationship between fiber length, fiber straightness, draft ratio, and the fiber accelerated point. Simultaneously, a time domain model was used to simulate the dynamic drafting process based on the straightening analysis, which provided an approach to capture the dynamic motion of different types of fibers and hook removal in the drafting zone. The model is validated by a previous study and experimental work, with the result that the output fiber straightness is both in a good agreement with those calculated by classical theories and experimental data. The straightening effect of the drafting process on four types of hooks under the same drafting conditions is compared. It is shown that the drafting effect on different types of hooked fibers is varied, with the clumped fiber removed preferentially followed by both end hooks or the trailing hook, whereas the leading hook is the most difficult to remove.