Li Yu, Li Shilei, Du Xiaobo, Qu Haijun, Wang Jianping, Bian Pingyan, Zhang Haiguang, Chen Shuisheng
School of Mechanical and Power Engineering, Henan Polytechnic University, Jiaozuo, Henan, China.
National Demonstration Center for Experimental Engineering Training Education, Shanghai University, Shanghai, China.
Sci Rep. 2024 Jul 6;14(1):15606. doi: 10.1038/s41598-024-66623-8.
Coaxial nozzles are widely used to produce fibers with core-shell structures. However, conventional coaxial nozzles cannot adjust the coaxiality of the inner and outer needles in real-time during the fiber production process, resulting in uneven fiber wall thickness and poor quality. Therefore, we proposed an innovative semi-flexible coaxial nozzle with a dynamic self-centering function. This new design addresses the challenge of ensuring the coaxiality of the inner and outer needles of the coaxial nozzle. First, based on the principles of fluid dynamics and fluid-structure interaction, a self-centering model for a coaxial nozzle is established. Second, the influence of external fluid velocity and inner needle elastic modulus on the centering time and coaxiality error is analyzed by finite element simulation. Finally, the self-centering performance of the coaxial nozzle is verified by observing the coaxial extrusion process online and measuring the wall thickness of the formed hollow fiber. The results showed that the coaxiality error increased with the increase of Young's modulus E and decreased with the increase of flow velocity. The centering time required for the inner needle to achieve force balance decreases with the increase of Young's modulus ( ) and fluid velocity ( ). The nozzle exhibits significant self-centering performance, dynamically reducing the initial coaxiality error from 380 to 60 μm within 26 s. Additionally, it can mitigate the coaxiality error caused by manufacturing and assembly precision, effectively controlling them within 8 μm. Our research provides valuable references and solutions for addressing issues such as uneven fiber wall thickness caused by coaxiality errors.
同轴喷嘴被广泛用于生产具有核壳结构的纤维。然而，传统的同轴喷嘴在纤维生产过程中无法实时调整内针和外针的同轴度，导致纤维壁厚不均匀且质量较差。因此，我们提出了一种具有动态自定心功能的创新型半柔性同轴喷嘴。这种新设计解决了确保同轴喷嘴内针和外针同轴度的挑战。首先，基于流体动力学和流固耦合原理，建立了同轴喷嘴的自定心模型。其次，通过有限元模拟分析了外部流体速度和内针弹性模量对定心时间和同轴度误差的影响。最后，通过在线观察同轴挤出过程并测量所形成中空纤维的壁厚，验证了同轴喷嘴的自定心性能。结果表明，同轴度误差随杨氏模量E的增加而增大，随流速的增加而减小。内针达到力平衡所需的定心时间随杨氏模量（ ）和流体速度（ ）的增加而减小。该喷嘴具有显著的自定心性能，能在26秒内将初始同轴度误差从380微米动态减小到60微米。此外，它还能减轻由制造和装配精度引起的同轴度误差，有效地将其控制在8微米以内。我们的研究为解决因同轴度误差导致的纤维壁厚不均匀等问题提供了有价值的参考和解决方案。
