茂金屬聚乙烯障壁型螺桿接流道式混合元件之最佳化設計

Abstract

本文是以m-PE為加工材料，高分子熔融行為主要是根據Tadmor熔融模式，數值方法在障璧螺桿部分是採用有限差分法而混合元件部份則是採用流動網格分析網路法(FAN)。以電腦模擬並搭配田口法對我們所採用的螺桿之幾何形狀進行最佳化的設計。 在本文中，我們引進了一評量數值「SN比」來進行最佳化的評比。此項評比標準相當的簡單而 且方便。只需要比較彼此的大小，大者為佳。接下來我們利用SN比根據押出量、螺桿最後一斷面之溫差及螺桿壓力來決定障壁螺桿之最佳幾何形狀。再探討在不同加工條件下，各障壁螺桿於押出性能上之表現，如固體床速度、熔融薄膜厚度、單位長度熔化速率、押出量、壓力分布、螺桿最後一 斷面與整體平均溫度之溫差等。進而探討障壁螺桿接混合元件之壓力表現，藉此對混合元件做幾何形狀之最佳化設計。

Computer simulation combined Taguchi method is used in optimal design of barrier flight geometry with m-PE as our processing material. For the barrier flight section, finite difference method based on the Tadmor melting model was utilized. However, flow analysis network was used to analyze the mixing element. In this study,「SN」ratio was used as our standard .However it is very simple and convenient. The bigger one is good. Then we search the optimal geometry of barrier flight with output rate, screw pressure, and temperature difference between last channel section and barrel with SN ratio. Subsequently, the effect of processing conditions on the screw performance, such as solid bed velocity, melt film thickness, melting rate per unit length, output rate, pressure build-up, temperature difference of last channel section and bulk temperature were discussed. In addition, pressure build-up in barrier flight with mixing element were also studied. In further, Searching the optimal geometry in mixing element.