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題 名 | 平行模穴充填過程黏性流體自由表面之研究 |
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作 者 | 李常聲; 沈永康; 陳明政; | 書刊名 | 國立臺灣大學工程學刊 |
卷 期 | 62 1994.10[民83.10] |
頁 次 | 頁1-19 |
分類號 | 440.137 |
關鍵詞 | 自由表面; 縫合線動力; 平行模穴; Flow front; Weld line dynamic; Parallel cavity; |
語 文 | 中文(Chinese) |
中文摘要 | 在射出成型充填過程申,前進流體之自由面運動進入模穴為完全發展流 的穩態行為;此影響殘留時間分佈及當凝固發生時巨觀分子流體之結構。本文中 高分子流體以牛頓,泛牛頓流模式來描述,自由面與模壁接觸之接觸點為不可積 分之奇異點,值得探討。本文使用葛磊金限元法求解非穩定狀態Navier-Stokcs方 程式,並以預測-修正法(predictor-corrector method)來計算時間域。在充填時,每 一時間間隔之流場及自由面位置必須計算,以了解高分子流體於模穴中流場特 性。 充填過程中,兩異向流相遇形成熔合線(weld line)。導致熔合線結合脆弱的原因 乃在於缺乏混台機制、熔流前界面的擴散(diffusion)以及因噴泉流現象使得熔合線 分子順向與熔流方向垂直所致;以上均為研究過程中已突破之重點,表徵於實例 解析中。 本文並對高分子流體流經不同截斷面所形成噴流(jetting flow)之自由面形狀及其 流場做深入探討,發現噴流並無噴泉流效應產生。 |
英文摘要 | The motion of free surface of advacing fluid flowing into a mold can be appreciablyfound from the steady behavior of well-developed flow. It affects the distributed residencetime and the structure of macro-molecular fluids while the solidification has taken place. Inthis paper such motion is treated numerically for newtonian and generalized newtonian fluids,in which the three-phase contact point represents a special singular problem conceptuallyand analytically. The algorithm of the method applied in this research combines the mixedGalerkin finite-element discretization of the governing equations with a predictor-correctorscheme for the integration in time domain. The flow field and free surface location aredetermined numerically at each time step. Collision of two flow fronts in cavity is another major fluid mechanism in the fillingprocess of injection molding. These transient free surface flows are in small-scale and inducesignificant impact upon the molecular orientation of molded parts. The weakness of weldline is the result of the lack of mechanical mixing and diffusion at the interface of meltfronts, and the fountain flow effects which produces a flow orientation at an angle of 90degrees to the flow direction at the weld line. A transient jetting flow also occurs in injection molding around junctures. The simulation results indicate that fountain flow may disappear in certain occasions. |
本系統中英文摘要資訊取自各篇刊載內容。