正向螺纹元件组合对反向螺纹元件熔体输送特性的影响

目的：探究熔体输送段正向螺纹元件间的不同组合对反向螺纹元件的熔体输送特性的影响。方法：通过改变导程构建两种不同模型，使用SolidWorks软件建立三维模型，使用Polyflow软件对两种模型在熔体输送段的挤出过程进行数值模拟，分析不同导程下螺纹元件的螺槽宽度及螺棱厚度对流场的影响及不同转速下流场的变化，通过实验验证转速对物料混合效果的影响。结果：所构建的模型均可使熔体通过反向螺纹元件；在相同螺杆转速下，由大导程螺纹元件构建的模型一建压能力和输送能力强于由小导程构建的模型二；模型一在分散混合能力上优于模型二，在分布混合能力上弱于模型二；在两端压差相同的情况下，增加转速可以提高物料的分散混合效果。结论：在聚乳酸改进加工过程中采用模型一且提高螺杆转速可进一步破碎物料，提高挤出物的质量。

Effcets of forward threaded element combination on melt transfer characteristics of reverse threaded element

Objective: Explore the effects of different combinations of forward screw elements in the melt conveying section on the melt conveying characteristics of reverse screw elements. Methods: Two different models were constructed by changing the lead, using SolidWorks software to establish a three-dimensional model, and using Polyflow software to numerically simulate the extrusion process of the two models in the melt conveying section. The effects of the screw groove width and screw edge thickness of the screw elements on the flow field under different lead lengths and the changes in the flow field at different rotational speeds were analyzed, and the effects of rotational speed on the material mixing were verified through experiments. Results: The constructed model can allow the melt to pass through the reverse threaded element. At the same screw speed, the pressure building capacity and conveying capacity of model one constructed from large lead screw elements were stronger than that of model two constructed from small lead screw elements. Model one was superior to Model two in terms of decentralized mixing ability, and weaker than Model two in terms of distributed mixing ability. Under the same pressure difference at both ends, increasing the rotational speed could improve the dispersion and mixing effects of materials. Conclusion: Using model one in the improved processing of polylactic acid and increasing the rotational speed of the screw can further crush the material and improve the quality of the extrusion.