Study On The Condensing Mechanism And Yarn Properties Of Compact Spinning With Lattice Apron

Compact spinning with lattice apron is one kind of new textile technology based on the technique of conventional ring spinning, pneumatical condense is used in this system to get fiber bundle into yarn. This technology catches lots of career men’s attention for its significantly enhance yarn properties. Currently, researches on spinning mechanism of compact spinng technology and compact-spun yarn structure as well as the relationship between spinning process and yarn quality were not thoroughly enough for its short developing history, which caused a great limited to optimizing compact system and improving compact technology. Therefor, system of compact spinning with lattice apron was regarded as the subject investigated in this paper, influences of airflow on fiber movemente was studied as the subject of researches, and on this basis, a series of works had been done.After precision measurement on each condense component of compact spinning with lattice apron firstly, the computational fluid dynamic model was established and was computerized with parallel technologies & standardκ-εturbulent model by computational fluid dynamics software FLUENT for simulating and characterizing the flow field in condense zone. Flowing state of airflow was characterized in condense zone, also distribution rules of static pressure and velocity and their effect on fiber bundle in inlet curved surface of suction slot were analyzed. Previous studies showed that airflow velocity is influenced by negative pressure, therefore, airflow characteristics under different negative pressure were simulated by the methods mentioned above. The results showed that the converging airflow was generated by negative pressure effects in this system; extracted velocities from the airflow filed and divided them into three different parts (X-axial velocity, Y-axial velocity and Z-axial velocity), it indicated that the effect of the each component velocities on fiber bundle was different, X-axial velocity component was the velocity which get fibers gathering, Y-axial velocity component made fibers keeping close to the surface of lattice apron and Z-axial velocity component helped to deliver the sliver. The simulation also showed that the airflow velocity was increased with the growth of negative pressure, but the increment rate of each axial velocity component was differerent.Then, on the basis of obtaining and extracting the distribution of velocity, dynamic model of infinitesimal element of fiber was established, and force analysis on single fiber in the airflow filed was completed, trajectories of fibers at different initial positions were simulated by specially designed MatLab procedure lastly. On top of that influences of processing parameters such as negative pressures and outer surface friction factor of lattice apron on fiber movement were studied. The research concluded that trajectories of fibers at different initial positions were different, fibers would gradually close and then pasted on the surface of lattice apron due to the effect of Y axial airflow filed; it also reflected that the compact spinning process in condense zone can be divided into three parts: fast convergence zone, adjustment convergence zone and steady convergence zone. Also it indicated that there was an optimum negative pressure, in which the system had the best compacting effect.The research in chapter three also showed that fibers were interlace and tanglement with each other during passed through the condense zone, which meant that additional twist may generate in this zone. Moreover, past productive practices and experiments study in this paper also demonstrated that the actual twist of compact-spun yarn is greater than ring spinning yarn produced under the same process conditions. To verify this appearance, a flexible fiber model which is assumed to be a chain that consists of n mass-quality beads connected by n zero mass rods was rebuilded, with stress analysis of fiber model and simulation by MatLab procedure, trajectories of fibers at different initial positions which was consistent with the result calculated by the infinitesimal element fiber model were simulated, the difference between these two results is that the new simulation result could discuss the reasons of fiber rolling and additional twist generation more vividly.Finally, according to the thought used in the theoretical research, experiment scheme was designed and yarns listed in the scheme were produced, then physical and mechanical properties of yarn such as hairiness, Uster properties, breaking force, elongation at break and twist and so on had been tested and compared, also the microscope was used to observed yarns’ longitudinal structure. The experiment results verified the validity of the theoretical research in this paper to some extent.Based on quantitive study on airflow filed in condense zone, a series of researches on compact spinning with lattice apron have been done and quantity of experiments have been done to verify the simulation results. Research in this paper made compact spinning theory tending to be more perfect, also it could provide a effective guideline for improving compact spinning process in future study.