Xuzhong Su

Research on pneumatic compact spun yarn quality

Compact spinning is one of the most important improvements of traditional ring spinning, which is implemented by adding a fiber condensing device to condense the fiber bundle and decrease the spinning triangle. Pneumatic compact spinning is the most widely used compact spinning method at present. Compact spinning with perforated drum and compact spinning with lattice apron are the two main kinds of pneumatic compact spinning. Therefore, in this paper, comparison analysis of yarn quality between compact spinning with perforated drum and compact spinning with lattice apron is presented. First, 9.7 tex cotton-combed yarn is spun in three different kinds of pneumatic compact spinning systems, including two kinds of compact spinning with perforated drum: Rieter’s COM4 and complete condensing spinning system (CCSS), and one lattice apron compact spinning system: Toyota’s four-line compact spinning. The test results of yarn qualities show that comparing with other two kinds of compact spinning systems, the yarn ...Compact spinning is one of the most important improvements of traditional ring spinning, which is implemented by adding a fiber condensing device to condense the fiber bundle and decrease the spinning triangle. Pneumatic compact spinning is the most widely used compact spinning method at present. Compact spinning with perforated drum and compact spinning with lattice apron are the two main kinds of pneumatic compact spinning. Therefore, in this paper, comparison analysis of yarn quality between compact spinning with perforated drum and compact spinning with lattice apron is presented. First, 9.7 tex cotton-combed yarn is spun in three different kinds of pneumatic compact spinning systems, including two kinds of compact spinning with perforated drum: Rieter’s COM4 and complete condensing spinning system (CCSS), and one lattice apron compact spinning system: Toyota’s four-line compact spinning. The test results of yarn qualities show that comparing with other two kinds of compact spinning systems, the yarn spun in CCSS has the best evenness, least long hairiness, and slightly lower strength. Then, the properties of spun yarns are analyzed using two methods. First, using Fluent Software, numerical simulations of three-dimensional flow field in condensing zone of three kinds of compact spinning system are presented, respectively. Second, the fiber movements in condensing zones are captured using high speed camera system OLYMPUS i-speed3.

Research on spun yarn qualities in a modified ring-spinning system using airflow-twisting device

In this paper, a kind of airflow-twisting devices which can produce the twist by the high vortex airflow is employed for improving the twist propagation process of ring-spinning system. Firstly, three different kinds of yarns Ne20, Ne40, and Ne60 are spun in this modified ring-spinning system with five different airflow pressures and two different swirling directions, including anticlockwise and clockwise, and the qualities of spun yarns, including hairiness, strength, evenness, and number of snarling characterizing the yarn residual torque, are measured. Secondly, the images of spinning triangles are captured by using a high speed camera system OLYMPUS i-speed3, and the mechanism of the effects of vortex airflow on yarn qualities is discussed by analyzing the fiber tension distributions in the spinning triangle. It is shown that for the ‘Z’ twist spun yarn, the spinning triangle decreases with the increasing of clockwise airflow pressures, whereas the triangle becomes more and more symmetrical with the increasing of anticlockwise airflow pressures. Meanwhile, the comprehensive qualities of spun yarn are improved with the increasing of both directions of airflow pressures to a certain extent. However, the hairiness and strength of spun yarn will be mainly improved with clockwise airflow, whereas yarn residual torque mainly reduced with anticlockwise airflow.In this paper, a kind of airflow-twisting devices which can produce the twist by the high vortex airflow is employed for improving the twist propagation process of ring-spinning system. Firstly, three different kinds of yarns Ne20, Ne40, and Ne60 are spun in this modified ring-spinning system with five different airflow pressures and two different swirling directions, including anticlockwise and clockwise, and the qualities of spun yarns, including hairiness, strength, evenness, and number of snarling characterizing the yarn residual torque, are measured. Secondly, the images of spinning triangles are captured by using a high speed camera system OLYMPUS i-speed3, and the mechanism of the effects of vortex airflow on yarn qualities is discussed by analyzing the fiber tension distributions in the spinning triangle. It is shown that for the ‘Z’ twist spun yarn, the spinning triangle decreases with the increasing of clockwise airflow pressures, whereas the triangle becomes more and more symmetrical with the i...

Research on fiber tension at asymmetric spinning triangle using the finite-element method

Spinning triangle is a critical zone in the ring spinning process of staple yarn, whose geometry influences the fiber tension distribution in the spinning triangle directly and determines the spun yarn qualities. In ring spinning, the spinning triangle is often asymmetric due to the inclination angle of the spinning tension or the migration of the axis fiber at the front roller nip. Therefore, in this paper, the fiber tension distributions in the asymmetric spinning triangle due to the migration of the axis fiber at the front roller nip were studied using the finite element method (FEM). In the direct finite-element model, the initial strain of the axis fiber is set as zero, and the accidental fiber tensions would be produced due to the asymmetric distributions of the initial strain on fibers in the two sides of the spinning triangle. Then, an effective finite-element model of the asymmetric spinning triangle with right (left) axis fiber migration for calculating the fiber tension is built by composing an...Spinning triangle is a critical zone in the ring spinning process of staple yarn, whose geometry influences the fiber tension distribution in the spinning triangle directly and determines the spun yarn qualities. In ring spinning, the spinning triangle is often asymmetric due to the inclination angle of the spinning tension or the migration of the axis fiber at the front roller nip. Therefore, in this paper, the fiber tension distributions in the asymmetric spinning triangle due to the migration of the axis fiber at the front roller nip were studied using the finite element method (FEM). In the direct finite-element model, the initial strain of the axis fiber is set as zero, and the accidental fiber tensions would be produced due to the asymmetric distributions of the initial strain on fibers in the two sides of the spinning triangle. Then, an effective finite-element model of the asymmetric spinning triangle with right (left) axis fiber migration for calculating the fiber tension is built by composing an asymmetric spinning triangle with a corresponding left (right) axis fiber migration and a symmetric spinning triangle is composed. Then, the fiber tension distributions in the spinning triangles in the Ne40 (14.6 tex) and Ne60 (9.7 tex) cotton spun yarn were numerically simulated with different axis fiber migrations and twist factors. Furthermore, the accuracy of the proposed finite-element model in calculating the fiber tension distribution in the asymmetric spinning triangle was validated by comparing it with the theoretical model built by the energy approach. It is shown that the numerical values of fiber tension distribution between the FEM results and the results with the energy method are in good agreement. Meanwhile, with the increase in the migrations of the axis fiber or the yarn twist, fiber tension in the spinning triangle is increased.

Theoretical study of spinning triangle with fiber concentric circular cones arrangement at front nip line

Spinning triangle is a critical region in the spinning process of staple yarn, which geometry influences the mechanical performances of fibers in the spinning triangle and determines the physical performance of spun yarns directly. Taking appropriate measures to reduce the spinning triangle and improve the qualities of yarn has attracted great interesting recently. In these modified ring spinning systems, the fibers in the spinning triangle are not arranged in the same plane, but arranged in concentric circular cones at front nip line, such as compact spinning, in which a fiber-converging device is installed on ring spinning frame, and the fiber bundle can be condensed before twisting in order to reduce the spinning triangle. Therefore, in this paper, a new theoretical model of fiber tension distribution in the spinning triangle with fiber concentric circular cones arrangement at front nip line is proposed based on the principle of minimum potential energy firstly. Then, corresponding residual torque within a yarn caused by the fiber tension is given. Finally, as an application of the proposed method, taking the spinning triangle in Ne40 cotton yarn 3-line rollers compact spinning as an example, the fiber tension distributions in the spinning triangle both with and without fiber buckling and corresponding residual torque within a yarn are numerically simulated, and the results are compared with those from earlier model. Furthermore, the properties of spun yarns produced by compact spinning system and ring spinning system are evaluated and analyzed.

Numerical analysis of fibers tensions in the Siro-spinning triangle using finite element method

Siro-spinning is a new kind of modified ring spinning method and achieved by feeding two rovings simultaneously, which have three spinning triangles including two primary spinning triangles and one final spinning triangle. In this paper, by using finite element method (FEM), the quantitative relationships between the fiber tension in the Siro-spinning triangle and some chosen important spinning parameters are investigated. The constituent fibers in the Siro-spinning triangle are considered as three-dimensional elastic beam elements with tensile, compressive, torsion, and bending capabilities. Then, the finite element model of Siro-spinning triangle is constructed under the assumption that the ends of all fibers gripped in the front roller nip distribute evenly, and the initial strain of the central fiber in each primary triangle is set as zero. Finally, the effects of some more important parameters of the Siro-spinning triangle, including the spinning yarn count, spinning tension, yarn twist, the distance between two feeding bell mouths on fiber tension distributions, are numerically examined and their quantitative relationships are discussed in detail. The accuracy of the proposed FEM model in calculating the fiber tension distribution of the Siro-spinning triangle has been validated by comparing it with our earlier theoretical models. Furthermore, the spinning experiments with different progress parameters were made, and the properties of spun yarns were evaluated and analyzed.

Research on mechanical properties of fibers at asymmetric ring spinning triangle using Finite Element Method

In the ring spinning process of staple yarn, spinning triangle is a critical zone, whose geometry influences the mechanical properties of fiber in the spinning triangle directly. In the practical spinning, especially in some modified ring spinning systems, the spinning triangle is often asymmetric, in which the horizontal deviation of the twisting point is existed and lead to an obvious angle between the yarn spinning tension and the vertical axis perpendicular to the nip line. Therefore, in this paper, the fiber tension distributions in this kind of asymmetric spinning triangle were studied using the finite element method. In the direct finite element model, the initial strain of fibers in the two sides of spinning triangle is asymmetric, and corresponding accidental fiber tensions would be produced, which makes the fiber move to the middle of the spinning triangle and lead to inaccurate results. Therefore, in the paper, one new finite element model of the asymmetric spinning triangle with left (right) h...In the ring spinning process of staple yarn, spinning triangle is a critical zone, whose geometry influences the mechanical properties of fiber in the spinning triangle directly. In the practical spinning, especially in some modified ring spinning systems, the spinning triangle is often asymmetric, in which the horizontal deviation of the twisting point is existed and lead to an obvious angle between the yarn spinning tension and the vertical axis perpendicular to the nip line. Therefore, in this paper, the fiber tension distributions in this kind of asymmetric spinning triangle were studied using the finite element method. In the direct finite element model, the initial strain of fibers in the two sides of spinning triangle is asymmetric, and corresponding accidental fiber tensions would be produced, which makes the fiber move to the middle of the spinning triangle and lead to inaccurate results. Therefore, in the paper, one new finite element model of the asymmetric spinning triangle with left (right) horizontal deviation was presented for calculating the fiber tension. In the model, an asymmetric spinning triangle with the same right (left) horizontal deviation was used to combine with the original asymmetric spinning triangle, and one axisymmetric quadrangle was built, and the symmetry axis is the central fiber. Then, the fiber tension and torque distributions in the spinning triangles of Ne40 (14.6 tex) and Ne60 (9.7 tex) cotton spun yarn were numerical simulated with different horizontal deviations and twist factors. Furthermore, the accuracy of the proposed finite element model in calculating the fiber tensions was validated by comparing it with the theoretical model built by the energy approach.

Research on shape of spinning triangles in the ring spinning system

Ring spinning is the most widely used yarn spinning method at present. Spinning triangle is a critical area in the ring spinning process of staple yarn, in which the geometry influences the distribution of fiber and fiber mechanical properties in the spinning triangle directly, and determines the qualities of spun yarn. Therefore, some new modified ring spinning methods have been appeared gradually by changing the spinning triangle actively. In this paper, the qualities of yarn spun by common ring spinning and two kinds of modified ring spinning were studied by analyzing the shapes of spinning triangle. First, 18.2tex cotton yarns were spun on FA507B ring spinning frame with three different spindle speeds and leading distances of top roller, and corresponding spinning triangles were captured using a high-speed camera system OLYMPUS i-speed3 and one kind of transparent front top roller. Then, the qualities of yarn produced by modified FA507B ring spinning system with four-line rollers compact spinning device and a kind of airflow twisting device were analyzed, respectively. 29.2tex, 14.6tex, 9.7tex yarns, and 18.2tex yarns with three negative pressures 1800, 2200, and 2600 Pa were spun, respectively, and corresponding spinning triangles were captured and analyzed comparatively. It is shown that using compact spinning device, the spinning triangle is reduced greatly, and with the increase in negative pressure, the spinning triangle is reduced gradually. Furthermore, 18.2tex yarns were spun on FA507B ring spinning frame and FA507B ring spinning system modified by a kind of airflow twisting device with airflow pressure 0.1Mpa and 0.05Mpa and two different swirling directions including anticlockwise and clockwise, and corresponding spinning triangles were captured and analyzed. It is shown that for the Z (S) twisting spun yarn, under the effects of the clockwise (anticlockwise) airflow, the spinning triangle can be reduced and benefit for reducing yarn hairiness, while under the effects of the anticlockwise (clockwise) airflow, spinning triangle is more symmetric and benefit for reducing the yarn torque possibly.

Theoretical study on a spinning triangle with fiber superposition

In some new modified ring spinning systems, fiber superposition in the front nip line often exists, that is, each fiber in the spinning triangle is not distributed evenly, but some fibers are divid...In some new modified ring spinning systems, fiber superposition in the front nip line often exists, that is, each fiber in the spinning triangle is not distributed evenly, but some fibers are divided into substrands or bundles. Therefore, in this paper, a theoretical model of fiber tension distribution in the spinning triangle is proposed by considering the fiber superposition at the spinning triangle based on the principle of minimum potential energy. The symmetric and asymmetric spinning triangle due to the inclination angle of the spinning tension and the migration of the axis fiber at the front roller nip were all considered, and theoretical models of fiber tension distributions in the corresponding spinning triangles were given. The relationships between the fiber tension and the spinning triangle shapes were studied. Finally, as an application of the proposed method, ring spinning triangles the 14.6 tex (40S) cotton yarn spinning were taken as an example for the simulation. The numerical simulations of fiber tension distributions in the spinning triangle were presented and analyzed comparatively. In particular, the effect of both fiber superposition and the distance between two adjacent substrands in the front nip on fiber tension distributions were discussed. The results show that when there is fiber superposition in the front nip, comparing with the case that each fiber is distributed evenly, the tensile force of the two boundary fibers is decreased slightly, and the compressive force of the central fibers is also increased slightly, which leads to similar magnitudes.

Research on evenness of section-color yarn

Section-color yarn is a kind of fancy yarn, which has discontinuous color changing on yarn axial direction and meets the needs of the market. Therefore, it is of high added value. In the section-color yarn spinning, one white roving is feeding into the back roller continuously, and one color roving is feeding into the middle roller discontinuously, and corresponding discontinuous color change on yarn axial direction can be produced. Compared to the common ring spun yarn, the evenness of section-color yarn is worsening seriously due to its spinning mechanism. Therefore, in this paper, the evenness of section-color yarn is analyzed. It is shown that the feeding deviation of color roving is the main possible reason for the worsening evenness of section-color yarn. Then, the corresponding measure for improving section-color yarn evenness is taken by modifying the feeding time of the back roller, and the corresponding modified spun yarn evenness is measured. It is shown that the section-color yarn evenness can...Section-color yarn is a kind of fancy yarn, which has discontinuous color changing on yarn axial direction and meets the needs of the market. Therefore, it is of high added value. In the section-color yarn spinning, one white roving is feeding into the back roller continuously, and one color roving is feeding into the middle roller discontinuously, and corresponding discontinuous color change on yarn axial direction can be produced. Compared to the common ring spun yarn, the evenness of section-color yarn is worsening seriously due to its spinning mechanism. Therefore, in this paper, the evenness of section-color yarn is analyzed. It is shown that the feeding deviation of color roving is the main possible reason for the worsening evenness of section-color yarn. Then, the corresponding measure for improving section-color yarn evenness is taken by modifying the feeding time of the back roller, and the corresponding modified spun yarn evenness is measured. It is shown that the section-color yarn evenness can be improved effectively, and the maximal improvement rate is 13.19%, which proves the effectiveness of the given method in this paper.

Effects of lattice apron density on yarn qualities in Four-line compact spinning system

In the paper, using finite element method (FEM), the effects of lattice apron density on yarn qualities in Four-line compact spinning system were studied by analyzing the numerical simulations of the airflow velocity. Firstly, three different kinds of yarns, 18.2tex (32S), 9.7tex (60S), and 5.8tex (100S), were spun on FA507B spinning frame equipped with lattice aprons of mesh size 150, 120, and 100, respectively. The hairiness, breaking strength, and evenness of spun yarns were tested and comparatively analyzed. Secondly, using FEM, the numerical simulations of the airflow velocity in the condensing zone were presented. The finite element model of condensing zone was constructed according to the physical parameters of the practical system. Then, the simulation of airflow velocities on five straight lines located in the front, middle, and back of condensing zone were given. It is shown that, in the whole condensing zone, for the lattice apron with mesh size 100, the direct transverse condensing force is high, but the assisted condensing force is low and disorder, which is not beneficial for yarn qualities. Compared to the lattice apron with mesh size 150, the usage of lattice apron with mesh size 120 may be beneficial for the high-count yarn condensing or the yarn condensing under the relatively lower negative pressures. Furthermore, taking the 9.7tex as an example, the trajectory of yarn movement in the condensing zone was given using high-speed camera system OLYMPUS i-speed3. Corresponding airflow velocities along the yarn movement path were presented.In the paper, using finite element method (FEM), the effects of lattice apron density on yarn qualities in Four-line compact spinning system were studied by analyzing the numerical simulations of the airflow velocity. Firstly, three different kinds of yarns, 18.2tex (32S), 9.7tex (60S), and 5.8tex (100S), were spun on FA507B spinning frame equipped with lattice aprons of mesh size 150, 120, and 100, respectively. The hairiness, breaking strength, and evenness of spun yarns were tested and comparatively analyzed. Secondly, using FEM, the numerical simulations of the airflow velocity in the condensing zone were presented. The finite element model of condensing zone was constructed according to the physical parameters of the practical system. Then, the simulation of airflow velocities on five straight lines located in the front, middle, and back of condensing zone were given. It is shown that, in the whole condensing zone, for the lattice apron with mesh size 100, the direct transverse condensing force is hi...