https://scholars.lib.ntu.edu.tw/handle/123456789/61992
標題: | 一模多穴流動平衡之實驗探討 | 作者: | 柯岱佑 | 關鍵字: | 流動不平衡;射出速度;模具溫度;螺桿背壓;融膠溫度;一模多穴;Multi-Cavity;flow imbalance;Injection Speed;Screw back-pressure;Melt Temperature;Mold Temperature | 公開日期: | 2004 | 摘要: | 一模多穴模具的優點在於大量生產、大幅降低成本及提高產業競爭力。然而多模穴射出成型因融膠流動不平衡問題,導致多模穴模具各模穴彼此之間的性質產生變異,造成元件品質不佳。本研究先觀察標準H型一模八穴對稱流道不平衡現象,找出其原因,並設計五種不同流道,找出最平衡流道系統。本研究並探討射出速度、融膠溫度、模具溫度與螺桿背壓四種成型參數對於五種流道設計而言,何者影響最大。最後針對五種流道實驗結果進行比較。 探討五種流道設計與成型參數對流動平衡影響結果顯示,融膠溫度與模具溫度可改善流動不平衡現象。其中以弧型流道B的效果最好,利用剪切熱效應的原因使融膠未充填完主流道,部分先轉入第二流道。H型流道中插銷的效果最差;主因在於流道中插銷增加融膠與流道間的摩擦而產生更多剪切熱。實驗發現螺桿計量固定下,射出速度越高,融膠流動長度不增反減,主因在於射速提高越快到達設定計量值,迫使射出機需馬上做出降低射出速度動作,避免超出所預設的計量,壓力因此隨即下降無法提供融膠流動的來源。 The multi-cavity molding is desired since it is advantageous for low-cost mass production. The design of multi-cavity mold is usually symmetric; however; shear heating makes the flow in symmetrical runners imbalanced, resulting in different flow length and quality in different cavities. To solve this problem, the flow imbalance phenomenon in the standard symmetrical H-type mold with eight symmetrical runners is first observed. Then, four molds with variations of symmetrical runners are designed, constructed and tested: Converging H-type runners, Pinned H-type runners, Curved A runners, Curved B runners. The flow balance of each system is observed and compared. The effects of four molding parameters: injection speed, melt temperature, mold temperature, and backing-pressure of screw on flow imbalance are investigated. Based on the observation of short-shots obtained from molding mold with eight symmetrical runner system, it is found that high melt and mold temperature can reduce the flow imbalance. High mold and melt temperature can reduce the shear heating effect. The experimental results of four modified symmetrical runners shows that the Converging H-type, Curved A-type, and Curved B-type runners can improve melt flow imbalance of the inner runners. Melt and mold temperature can reduce the flow imbalance. within 230~237.5℃. Curved B-type shows the best improvement. Pinned H-type runners worsen the flow imbalance; the flow in the pinned runners increases the shear heating. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/61331 | 其他識別: | zh-TW |
顯示於: | 機械工程學系 |
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ntu-93-R91522714-1.pdf | 23.53 kB | Adobe PDF | 檢視/開啟 |
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