外部氣體輔助成型之氣體保壓效果探討

Study on Packing Effects of External Gas-Assisted Injection Molding

黃信義(Hsin-Yi Huang)

指導教授 ： 陳夏宗

中原大學/工學院/光機電及資電控產業研發碩士專班/碩士(2007年)

https://doi.org/10.6840/cycu200700612

摘要

摘要
現今塑膠已經成為所有產品最基本原料，而塑膠加工又以射出成型擁有質輕、低成本、快速及一體成型的優點最為廣泛應用。而射出成型趨向薄件及大面積成品，在傳統的熔膠保壓已經無法達到要求品質，而利用外部氣體輔助成型用來改善品質要求。目前僅有專利說明外氣成型方法以及可提升表面品質，並未針對成型過程模內的壓力以及成型後收縮加以探討。
在本研究中，設計一個長250mm、寬100mm及厚2mm，由短邊處進膠之實驗模具。並從模具澆口開始，沿流動方向（距離10mm、120mm、230mm）安裝三個壓力感測器。比較在無保壓、熔膠保壓及外部氣體保壓的參數變化下，分別測量成型過程中的模穴內部的壓力分佈情形及成型後成品重量及尺寸收縮率。
研究結果顯示利用外部氣體保壓成型時，在三個壓力感測器間壓力差小於5.35Bar，且不同模次間有良好的重現性及穩定性。在比較無保壓的成品重量後，使用熔膠保壓時會有9.39~9.96%的重量增加以及2倍的誤差；而外部氣體保壓時重量增加在1%內以及1.07倍的誤差。利用氣體保壓產生的模穴壓力只要熔膠保壓最大壓力的四分之一以下，就可以有熔膠保壓時69.5%的抵抗流動方向收縮率。另外在流動方向收縮的效果雖然僅有熔膠保壓的56.1~72.7%，但是因為氣體均勻對整個厚度方向的保壓推擠，所以在厚度方向會有熔膠保壓的-1.27～-21.66％的收縮率。使用外氣成型有均勻穩定且無壓力損失的保壓，且抵抗流動方向及表面收縮，因此適用於成型薄件及大面積的成品。

關鍵字

收縮率 ； 外部氣體輔助成型 ； 保壓效果

並列摘要

ABSTRACT
The polymer has become the basic material of products recently. Then injection molding is widely used in the polymer process. Because of its advantages such as fast, light, low-cost and all-in-one. Nowadays products are getting thinner and larger. The most important thing for products is to prevent shrinkage and warpage, but it is not enough by using melt packing. So external gas molding has developed for solving these problems.
In this study, we build a rectangular mold with high L/T (>100). Then we measured pressure by three pressure sensors which installed along the melt flow direction. Finally, we compared the in-mold pressure under the situation that no melt packing, melt packing and external gas packing during molding process. Also we measured mass and shrinkage of products and compared it as well.
As a result, Observe from in-mold pressure can obtain, the external gas molding has uniform packing effect at overall molded, and another has good repeatability and stability. External gas preventing shrinkage achieved 70% of melt packing effect, just only making less then 25% in-mold pressure. Using melt packing increase weight with 9.39~9.96% and diversity up to double, when used external gas packing increase less then 1% and diversity up to 1.07 times. Although external gas packing only has melt packing with 56.1~72.7% effect on shrinkage along flow direction, but uniform packing surface agree with thinner and larger article.

並列關鍵字

external gas molding ； packing effect ； shrinkage

參考文獻

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