Wenliang Xue

A Study of the Twisted Strength of the Whirled Airflow in Murata Vortex Spinning

In Murata vortex spinning, the highspeed whirled airflow twists the open-end trailing fibers converged at the inlet of the hollow spindle into a yarn. The twisted strength acting on the vortex spun yarn by the whirled airflow was investigated by an analytical model based on simulating the flow field inside the nozzle block. The results showed that the twisted strength acting on the vortex spun yarn by the vortex could be regarded as the following functions: (1) the number of jet orifices, the jet angle, the inner diameter of the jet orifice and the nozzle block; (2) the distance from the inlet of the nozzle block to the inlet of the hollow spindle; (3) the projecting height of open-trail-end fibers twined over the top exterior of the hollow spindle; (4) the vortex spun yarn diameter; and (5) the velocity at exit of the jet orifice (i.e. corresponding to nozzle pressure). Increasing the velocity at exit of the jet orifice increased the strength twisted by the whirled airflow. The strength twisted by the whirled airflow increased with decreasing inlet diameter of the nozzle block, and was enhanced with increasing outer diameter of the hollow spindle. The strength twisted by the whirled airflow was weaker when the distance from the inlet of the nozzle block to the inlet of the hollow spindle was bigger. The numerical results validated the effectiveness of the analytical model.In Murata vortex spinning, the highspeed whirled airflow twists the open-end trailing fibers converged at the inlet of the hollow spindle into a yarn. The twisted strength acting on the vortex spun yarn by the whirled airflow was investigated by an analytical model based on simulating the flow field inside the nozzle block. The results showed that the twisted strength acting on the vortex spun yarn by the vortex could be regarded as the following functions: (1) the number of jet orifices, the jet angle, the inner diameter of the jet orifice and the nozzle block; (2) the distance from the inlet of the nozzle block to the inlet of the hollow spindle; (3) the projecting height of open-trail-end fibers twined over the top exterior of the hollow spindle; (4) the vortex spun yarn diameter; and (5) the velocity at exit of the jet orifice (i.e. corresponding to nozzle pressure). Increasing the velocity at exit of the jet orifice increased the strength twisted by the whirled airflow. The strength twisted by the wh...

Analysis of the Fiber Spatial Trajectory in Vortex Spun Yarn

The principle and the process of yarn formation determine fiber migration and twist radial distribution in a yarn. Usually tracer fiber technology is introduced to discuss fiber configuration in the yarn body. There are few studies on fiber spatial configuration based on the principle and the process of yarn formation. In this paper, we discuss fiber spatial trajectory in vortex spun yarn from the viewpoint of the principle and the process of yarn formation. Based on the fiber movement rule, the parameter equations of fiber spatial trajectory in vortex spun yarn were established. The fiber spatial configuration and its influenced factors were analyzed. The research results showed that the fiber spatial configuration in vortex spun yarn consisted of the core fiber and the migration wrapper fiber as well as the regular wrapper fiber. The fiber spatial configuration in vortex spun yarn was affected by the following factors: delivery speed, distance from the front roller nip point to the hollow spindle, mean ...The principle and the process of yarn formation determine fiber migration and twist radial distribution in a yarn. Usually tracer fiber technology is introduced to discuss fiber configuration in the yarn body. There are few studies on fiber spatial configuration based on the principle and the process of yarn formation. In this paper, we discuss fiber spatial trajectory in vortex spun yarn from the viewpoint of the principle and the process of yarn formation. Based on the fiber movement rule, the parameter equations of fiber spatial trajectory in vortex spun yarn were established. The fiber spatial configuration and its influenced factors were analyzed. The research results showed that the fiber spatial configuration in vortex spun yarn consisted of the core fiber and the migration wrapper fiber as well as the regular wrapper fiber. The fiber spatial configuration in vortex spun yarn was affected by the following factors: delivery speed, distance from the front roller nip point to the hollow spindle, mean angular velocity for the open-end trailing fiber, fiber length, and vortex spun yarn diameter.

Intelligent detection of defects of yarn-dyed fabrics by energy-based local binary patterns

For the purpose of realizing fast and effective detection of defects of yarn-dyed fabric via computer vision, and in consideration of the inherent characteristics of texture, that is, color and structure, an applicable approach for intelligent defect detection is proposed in this paper. The image of yarn-dyed fabric enhanced by fractional differentials is first converted from RGB true color space to L*a*b* color space, and energy-based feature images are acquired after the Log-Gabor filter filters chromatic and brightness channels. Then the paper defines the relations between energy and the local binary pattern as a new concept called energy-based local binary patterns (ELBPs). Finally defects can be detected, using ELBPs rather than grayscale-based local binary patterns. The proposed method can detect chromatic and structural defects. Experimental results for the defect detection from several collections of yarn-dyed fabrics indicate that a detection success rate of more than 94.09% is achieved for the proposed method, and the speed of test is also fast.

Theoretical analysis on the yarn twist mechanism of self-twist jet vortex spinning

In this paper, the hollow spindle receives self-twist modifying treatment, which makes the surface friction coefficient of the hollow spindle increase. When the sliding friction torque is enough to overcome the torsional stiffness of the fiber, under the force of the high-speed airflow, the fiber scrolls on the surface of hollow spindle, resulting in fiber twist, which increases the cohesion between the fibers, improving yarn strength. Based on the flow field simulation of the self-twist jet vortex spinning, it establishes the mechanical system of the free-end self-twist motion of the fiber in the flow field, and analyzes the fracture mechanism of the self-twist jet vortex spinning yarn. It provides more comprehensive support for the design and processing of the key components of the self-twist jet vortex spinning system.

Comparative analysis of different jet vortex spinning hollow spindle groove structures on yarn mechanism and yarn properties

According to the self-twist jet vortex spinning process, the free fiber end lays flat and rolls rotationally on the surface of the stationary hollow spindle under the high-speed rotating airflow and the tangential friction torque, which results in the self-twist of the fiber. The self-twist will be wound into the yarn body and increases the friction and the cohesion between the fibers in the yarn, which will improve the strength of the yarn. Based on mechanical analysis and numerical simulation, this article obtains the motion trajectory of the free fiber end and designed six different hollow spindle groove micro-feature structures. Combined with experiments, this article analyzes comparatively the influence of different hollow spindle groove micro-feature structures on the free fiber end and the yarn performance, which lays the foundation for the research and the development of jet vortex spinning.

Comparative analysis on yarn mechanism and yarn properties of different jet vortex spinning systems

Changing the process of jet vortex spun yarn will result in the change of its structure, and further changing its properties. In this article a comparative study is carried out about three aspects, namely the internal structure of the nozzle, the internal flow field distribution of the nozzle, and the yarn properties of MVS861 and MVS870. The correlation between the yarn formation process and yarn properties will be discussed theoretically, which will be validated by designed experiments. There is significant meaning for researching the correlation between yarn formation process and yarn structure because, on the one hand, it can optimize the process of yarn formation and improve the structure of key components used to form yarn, and on the other hand, it can guide theoretically the design of the yarn structure.

Numerical simulation and analysis of airflow in the condensing zone of compact-siro spinning

Compact-siro spinning is a new kind of spinning technique that combines compact spinning and siro spinning, and is widely put into practice. In this paper, a simulation and characterization of the flow field in the condensing zone are made by computational fluid dynamics software. It mainly includes the distribution rules of static pressure and velocity. According to the relative references and factory condition, several orthogonal and control experiments have been done. Through testing the strength, evenness and hairiness properties and analyzing and comparing the results with the data of three different suction slots, we select the compact-siro spinning suction device whose yarn has the best overall performance. The theory analysis gives foundation and explanation for the experiment, and also provides a theoretical basis for optimizing the properties of compact-siro yarn in production practice.

Numerical simulation and analysis of the dynamic finite element model of the fiber motion in the air spinning process

Under the spinning technology of the air-assisted twisting, this paper established the fiber finite element model, which has the structural and dynamic characteristics of the fiber flexible body, based on the space elastic thin rod unit. In this research, we deduced the static equilibrium equation of the fiber finite element model. The nonlinear geometric displacement large deformation problem of the space elastic thin rod unit was treated by the method of stepwise loading successive approximation, and the finite element simulation and analysis of the fiber flexible body’s movement and deformation during the air-jet twisting were carried out and verified by experiment in this paper. This research presents an effective and feasible theoretical model and method for the flexible fiber twisting formation process and mechanism under the high velocity vortex airflow.

Numerical simulation of the fiber trajectories in vortex spinning under different process parameters based on the finite element model

This paper studied the fiber movement in vortex spinning based on the flexible fiber finite element model, according to the theoretical mechanical analysis of the vortex spun yarn forming process. The finite element simulation and analysis of the different trajectories of free-end fiber in vortex spinning under different process parameters were carried out. The influence of the fiber count, fiber bending stiffness and nozzle pressure on the fiber transfer and distribution was analyzed and verified by experiments of tracer fiber and yarn slicing. The numerical simulation and the experiments’ results show a consistent correlation of different process parameters and fiber movement, such as the fiber diameter increasing, the fiber bending stiffness increasing, the nozzle pressure decreasing, and the fiber tending to get a smaller twist angle and becoming more easily distributed in the center of the yarn. This paper provides a theoretical basis for the structure design of vortex spun yarn and the production practice of vortex spinning.

An improvement design of groove-wound clothing on the licker-in—Part I. Theoretical analysis and modeling validation:

This paper argues that the groove-wound licker-in racks’ spiral mounting leads teeth with an inclination angle to the rotating direction. Theoretical analysis of forces on the fibers is carried out when the inclination angle is 0 and θ: when the teeth enter the fiber layer, the inclination angle makes the pressure on fibers increases rapidly and leads to a stronger friction force on fibers. It also leads to increases in both contact area and the wrap angle of the fiber around the teeth. This article also uses ANSYS Explicit Dynamics to simulate the fiber assembly carded by a tooth, when the inclination angle is 0°, 1° and 2°. When the inclination angle of the model is 1°, its fiber deformation is 1.35 times that of 0°; its elastic strain and stress concentration coefficient are 1.40 times than that of 0°; when the inclination angle of the model is 2°, its fiber deformation is 1.72 times than that of 0°; its elastic strain and stress concentration coefficient are 2 times than that of 0°. As with the inclinations increasing, the fiber deformations increase in time grow from 0.0634 and 0.08477 to 0.10584. The simulation also shows that when the tooth works on the fibers, there is a sudden compressive stress on fibers and then this pressure transfers with time. From all of the above, the inclination angle on licker-in teeth results in larger strain and deformation on fibers, so that this inclination angle should be decreased as much as possible in practice.