He You, Liu Huanlao, Wang Yulin, Hu Weikang
Guangdong Engineering Technology Research Center of Small Household Appliances Innovation Design and Manufacturing, School of Mechanical Engineering, Guangdong Ocean University, Zhanjiang 524088, China.
Polymers (Basel). 2025 Jan 2;17(1):102. doi: 10.3390/polym17010102.
During the production of medical thin-walled tubes, a thin coating layer is required. This requirement reduces the cross-sectional clearance area of the straight section flow channel formed by the mandrel and the die, leading to excessive pressure of the polymer melt at the shaping section, elevated die pressure, and backflow of the material melt, all of which directly impact the quality of the coating layer. To address these issues, this study conducted a non-isothermal numerical simulation of coating models both with and without a shaping section. It analyzed the impact of the coating model without a shaping section on the coating layer's thickness and the stability of the coating flow field under varying drag velocities, inlet flow rates, and die temperatures. Furthermore, it compared these results with those of coating extrusion using shaping section runners and investigates how different flow channel parameters affect the extrusion characteristics of the coating layer. The results showed that the setting of the shaping section could not eliminate the extrusion expansion in wrap extrusion. In comparison to coating extrusion utilizing a shaping section die, the process without a shaping section die reduced die pressure drop by 35% to 40%, decreased energy consumption, and enhanced the quality of the coating layer. Finally, an amorphous segment-coating extrusion die was designed based on the simulation results, and coating extrusion experiments were carried out using the designed and fabricated die.
在医用薄壁管的生产过程中，需要一层薄涂层。这一要求减小了由芯轴和模具形成的直段流道的横截面积间隙，导致聚合物熔体在成型段压力过大、模头压力升高以及物料熔体回流，所有这些都会直接影响涂层质量。为了解决这些问题，本研究对有无成型段的涂层模型进行了非等温数值模拟。分析了无成型段的涂层模型在不同牵引速度、入口流速和模头温度下对涂层厚度和涂层流场稳定性的影响。此外，将这些结果与使用成型段流道进行涂层挤出的结果进行了比较，并研究了不同流道参数如何影响涂层的挤出特性。结果表明，成型段的设置并不能消除包覆挤出中的挤出膨胀。与使用成型段模头的涂层挤出相比，无成型段模头的工艺使模头压力降降低了35%至40%，降低了能耗，并提高了涂层质量。最后，根据模拟结果设计了一种非晶段涂层挤出模头，并使用设计制造的模头进行了涂层挤出实验。
