A STUDY ON THE PERFORMANCE OF BARRIER-SCREW EXTRUDERS
A STUDY ON THE PERFORMANCE OF BARRIER-SCREW EXTRUDERS
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DOI：
10.1002/pen.760311110
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发表时间：
1991-06-01
影响因子：
3.2
通讯作者：
WHEELER, NC
中科院分区：
文献类型：
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作者：
HAN, CD;LEE, KY;WHEELER, NC
对阻隔螺杆挤出机的性能进行了实验和理论研究。在实验研究中，使用带有戴维斯标准阻隔螺杆的挤出机(D=63.5 mm，L/D=24)挤出低密度聚乙烯。挤出机有9个压力传感器，它们沿挤出机轴线几乎等距地安装在挤出机机筒的壁上，这样我们就可以测量挤出过程中的轴向压力分布。还进行了示踪实验(即螺杆“推出”实验)，使我们能够检查固体通道中熔体膜厚的分布。在理论研究方面，对ElBirli等人的分析进行了扩展，做了以下修改：(A)将通过屏障飞行间隙的流动与固体床上方的熔体膜流动分开处理；(B)假定固体床周围的熔体膜绕固体床循环；(C)在固体床周围的熔体通道和熔体膜的能量方程中考虑了对流换热。轴向压力分布的预测值与实验值吻合较好。预测了挤出条件对上、下层油膜厚度和固床速度的影响。从阻挡螺杆的设计和阻挡螺杆挤出机的选择两个方面讨论了这些结果的实际意义。
An experimental and theoretical study was conducted on the performance of barrier-screw extruders. For the experimental study, an extruder (D = 63.5 mm and L/D of 24) with a Davis-Standard barrier screw was used to extrude a low-density polyethylene. The extruder had nine pressure transducers which were mounted, almost equally spaced along the extruder axis, on the wall of the extruder barrel, so that we could measure axial pressure profiles during extrusion. Also conducted were tracer experiments (i.e., screw 'pushout' experiments), which enabled us to examine the profiles of melt film thickness in the solid channel. For the theoretical study, the analysis of Elbirli, et al, was extended by making the following modifications: (a) the flow through the barrier flight clearance was treated separately from the flow of melt film above the solid bed; (b) the melt films surrounding the solid bed were assumed to circulate around the solid bed; and (c) convective heat transfer was included in the energy equations for the melt channel and melt films surrounding the solid bed. Prediction of axial pressure profile was found to be in reasonable agreement with experiment. Predictions are presented of the effects of extrusion conditions on the thicknesses of the upper and lower films, and on the solid-bed velocity. Practical implications of these results are discussed from the view of designing barrier screws and selecting barrier-screw extruders.