Study On Mechanism And Property Of Yarn In Compact Spinning With Pneumatic Groove

On compact spinning study, the main purpose is on the change of the spinning craft to meet the request of the high-grade fabric and weave. It has already become the focus study both at home and abroad, and it is regarded as a new spinning technology of "21 "century.The mechanisms of condensing fiber bundles, determined by different condensing components in current compact spinning systems, are classified three categories:aerodynamic convergence (Zinser by Air-com-Tex 700 and Suessen by Elite as well as Rieter by K45 etc), mechanical convergence (Rotorcraft by ROCOS) and mechanical-pneumatic convergence (Donghua University by compact spinning with pneumatic groove).In this work, we will investigate the compact spinning with pneumatic groove, which will also produce positive influences on the industrial application of compact spinning technology to the reform of domestic conventional ring spinning frame.The research work includes that:(1) In compact spinning with pneumatic groove, the computational fluid dynamic model, computed with parallel technologies & FLUENT 6.3, will be developed to simulate the flow field in convergence zone with 3D CFD technology. Flowing state, distributions of static pressure and velocity in convergence zone will be characterized and analyzed.The results show that the compact principle of compact spinning with pneumatic groove consists of compact by airflow and compact by the shape of the pneumatic groove; the fluctuation of the static pressure and velocity near the bottom of the pneumatic groove is relatively bigger and the number of the fluctuation is equal to the number of the round hole in convergence zone; X-velocity component of airflow makes the fiber bundle converge, and Y-velocity component of airflow lets the fiber bundle slide into the groove, which results into the convergence of the fiber bundle by shape of the groove.(2) To study the condensing process and mechanism analysis of compact spinning system with pneumatic groove, flowing state will be analyzed in the convergence zone, then trajectory of the fiber bundle in the flow field will be simulated by MATLAB procedure, and the condensing effect of airflow for fibers will also be analyzed. The results show that the fiber bundle would be condensed only by the effect of airflow before it reaches the groove and when sliding into the groove, it gets effects from both airflow and shape of the groove; edge fibers of the fiber bundle are condensed by airflow, and the condensing width of fibers is dependent upon the effect of air-flow filed; the positions of fibers at different width change as a result of airflow, and the phenomenon of migration of fibers is to take place in the section of the fiber bundle.(3) To further study the compact spinning system with pneumatic groove and improve the yarn quality, the twist propagation analysis of compact spinning system with pneumatic groove will be analyzed, then the change of spinning tension in infinitesimal radian will be analyzed in the twist propagation, and the equations of spinning tension will be also given. This paper will analyze the moment of resistance to twist and the moment of torsion in process of twist propagation. The results show that the spinning tension and the negative pressure in air suction pipe as well as related structure parameters of the pneumatic groove roller affect the twist propagation; for a designed compact spinning system, the negative pressure in air suction pipe and the spinning tension are adjusted for meeting the change of the compact yarn properties.(4) By the experiment on 6 spindles ring frame FB502 which is assembled by the compact spinning apparatus, the optimal parameters of air force and the size of bead ring can be obtained, and compare and analyze the performance criteria of the 20s,40s and 60s compact yarn between compact spinning and ring spinning. The results show that comparing with conventional ring spinning yarn, both the strength and breaking strength of compact yarn are enhanced, in particular, the greatly reducing number of yarn hairiness; the compact yarn strength is increased by 7%～14%, and the Uster CV%fails down by 4%～8%while the quality of 3-9mm hairiness is reduced by 16.61%～86.01%; as the yarn count increasing, the compact effect of 20s,40s and 60s yarn keeps the upward trend, reaching the expected goal and fully reflecting the superiority of the compact yarn.