Longdi Cheng

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.

Enzymatic treatment of mechanochemical modified natural bamboo fibers

Natural bamboo fibers have attracted growing demands in textile industry due to benefit from their excellent properties and renewable and abundant resource; however, there are still limitations for their application in textile industry because of their poor quality. For this reason, enzymes treatments on mechanochemically modified natural bamboo fibers were conducted to extract noncellulosic matters from finer natural bamboo fibers in this paper. Four enzymes, pectin lyase, xylanase, laccase, and cellulase, were used to remove pectin, hemicellulose, lignin and to loosen the compact structure of fibers, respectively. Furthermore, the concentrations of four enzymes were optimized in terms of fiber chemical composition, weight loss, fineness, and tenacity to obtain high quality fibers. An obvious reduction in amount of noncellulosic substances and also a remarkable improvement in fineness in the modified fibers can be found from the experimental results. The optimum parameters are determined as: 0.6 % pectin lyase, 1.2 % cellulase, 0.3 % xylanase, and 1.2 % laccase; and the natural bamboo fiber thus obtained is 77.51 % in cellulose content, 2.81 tex in fineness, and 2.62 cN/dtex in tenacity.

Optimal design of superfine polyamide fabric by electrostatic flocking technology

The use of superfine fibers as piles to produce flocked fabrics is underreported despite their excellent properties. Therefore, a superfine polyamide fiber was used for piles to produce flocked fabric in this study, and a full factorial design was employed with three design factors at three levels to optimize the process parameters in terms of flocking density. The flock density is found, experimentally, to increase with the decrease of flocking distance and the increase of field strength and flocking time. A ternary linear equation is also established in this study based upon the regression analysis on experimental results and verified by F-test showing that it has remarkable significance. Comparison with experimental values shows that the regression equation possesses high accuracy. The optimum parameters are empirically and experimentally determined as: flocking distance of 7 cm, field strength of 60 kV, and flocking time of 10 s.The use of superfine fibers as piles to produce flocked fabrics is underreported despite their excellent properties. Therefore, a superfine polyamide fiber was used for piles to produce flocked fabric in this study, and a full factorial design was employed with three design factors at three levels to optimize the process parameters in terms of flocking density. The flock density is found, experimentally, to increase with the decrease of flocking distance and the increase of field strength and flocking time. A ternary linear equation is also established in this study based upon the regression analysis on experimental results and verified by F-test showing that it has remarkable significance. Comparison with experimental values shows that the regression equation possesses high accuracy. The optimum parameters are empirically and experimentally determined as: flocking distance of 7 cm, field strength of 60 kV, and flocking time of 10 s.

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.

Numerical simulation of fiber strands on condensing effect of suction slot in compact spinning with lattice apron

Compact spinning technology is through the airflow force to get fiber strands to be compacted in the condensing zone. In this paper, it makes a deeper study on the morphological changes and movement process of fiber strands in the flow field of condensing zone. Based on the airflow data in the condensing zone, the geometrical model of single fiber is built, and then the trajectory of single fiber can be got. The difference of trajectory and compact effect of fiber strands is also analyzed in the condensing zone of straight, oblique and deformed suction slots.

Study of the Tensile Properties of Jute / Cotton Blended Yarns Using Weibull Distributions

Jute fibre, a natural composite of cellulose, hemicellulose and lignin, occupies the second place to cotton in economic importance. Recently many attempts have been made to produce fine jute blended yarn with other textile fibres. In this paper, the two types of jute/cotton blended yarn whose jute and cotton fibres were respectively blended at the opening and drawing stages were spun by using the ring spinning technology. The tensile properties of both blended yarn at gauge lengths from 150 mm to 500 mm were investigated, and the evenness and imperfections for both blended yarn were also evaluated. The results show that the draw frame blended yarn was of better quality than the opener blended yarn. The breaking tenacities of both blended yarn increased with the decrease in the gauge length. The equations derived from two-parameter Weibull distribution and based on experimental strength at length of 300 mm can predict the breaking strength of both blended yarn accurately. The scale effect study indicates t...

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.

Investigation of fiber trajectory affected by some parameter variables in vortex spun yarn

The principle and process of yarn formation determines fiber trajectory in a yarn. The objective of this paper was to investigate the effect of some parameter variables on the fiber trajectory of vortex spun yarn produced by the MVS No. 861 spinner, based on tracer fiber and image mosaics techniques. Some typical fiber configurations in vortex spun yarn were also observed. It was found that fiber trajectories in vortex spun yarn are affected significantly by the following parameters: fiber specification, distance between the front roller nip point and the tip of the hollow spindle, nozzle pressure, and yarn delivery speed, as well as yarn linear density. Some typical fiber configurations of vortex spun yarn include straight, ideal trajectory, hooked (trailing, leading, and both ends), looped, and entangled. Increasing the fiber length or decreasing the distance between the front roller nip point and the tip of the hollow spindle will result in an increase of the core fiber length in vortex spun yarn. The mean pitch of wrapper fiber decreases with the decrease of fiber fineness and yarn delivery speed, while its mean wrapper angle takes on an inverse trend affected by fiber fineness and yarn delivery speed. The mean pitch of wrapper fiber increases with decreasing nozzle pressure and yarn linear density, while its wrapper angle is smaller when nozzle pressure is lower and vortex spun yarn is coarser.