衝擊式微射出成型系統開發研究

Development of a Pneumatic Impact Micro-Injection Molding System

粘世智(Shih-Chih Nian)

指導教授 ： 楊申語

國立臺灣大學/工學院/機械工程學研究所/博士(2005年)

https://doi.org/10.6342/NTU.2005.03047

摘要

摘 要

隨著微機電系統、精密光學及生醫技術的蓬勃發展，高精度微細元件的製造技術日益重要。由於高分子材料成型性最佳，最容易大量且價廉的翻製高精度的微細元件，其中微射出成型更因製程的高度自動化而成為微細元件最經濟且快速的成型方法。
由於微量射出與傳統射出在特性、需求上有極大差異，本論文之主要目的在開發以氣壓驅動之衝擊式微量射出成型系統，並使用該衝擊式微射出成型機對微射出成型作一系統化之研究及探討，包括：成型操作窗、成品品質、融膠流動狀態及參數影響等主題。本論文第一部份陳述衝擊式微射出成型機之設計概念、主體結構、作動方式及基本測試。第二部份利用色粒輔助觀察衝擊射出成型之融膠流動，以高速攝影系統透過透明視窗觀察融膠在渦線模具內的流動行為，探討衝擊射出之融膠流動狀態。第三部份探討操作參數對衝擊射出的影響，藉由渦線模具流動觀察並輔以簡易之模擬程式，交叉分析各參數對融膠充填的影響，建立衝擊射出的參數設定依據。第四部份研究超薄拉伸試片之成型操作窗及其成品品質，以拉伸試片模具為載具，結合變模溫系統，定義出微射出成型之操作窗，並得出於不同參數下的拉伸試片的光彈分佈狀態。第五部份藉表面微凸透鏡片陣列光學元件的衝擊射出，以探討衝擊射出參數對表面微結構轉寫性的影響。
所開發之衝擊式微射出成型機經過不斷的改良，衝擊速度可達到每秒6500 mm 以上，並可穩定的完成射出流程。在衝擊式微射出成型機之性能探討部份，從渦線模具的流動觀察與模擬之結果顯示：基本上充填型態仍以噴泉流為主；模穴越深流長越長；模具溫度對薄件影響極大；融膠溫度對各厚度均有影響；氣壓及衝錘重量可供調整衝擊能量並控制渦線模穴的充填。在拉伸試片實驗的結果顯示：較厚的零件及較低的模溫具有較大的操作窗，而模溫的升高有助於短射區域之縮小，但產品的收縮會更加劇烈。在表面微鏡片陣列光學元件射出的實驗結果顯示：微鏡片陣列之複製性良好，只要保壓壓壓力不要過低皆可達到複製之要求，而高模溫或低保壓壓力下成型之表面微鏡片陣列易有較大的收縮變形。

關鍵字

衝擊射出 ； 流動觀察 ； 衝擊式微射出成型 ； 流動觀察 ； 射出成型 ； 微射出成型

並列摘要

Abstract
In recent years, interest has been growing in fabrication of polymer-based Micro-Electro-Mechanical Systems (MEMS). Such products show great potential in optical and biological applications. Among polymer-based fabrication methods, micro-injection molding is versatile, precise, cost-effective, and highly productive.

Because micro-injection molding differs greatly from the traditional injection molding, a new design and construction is needed. A novel pneumatic impact micro-injection machine is constructed in this study. The molding characteristics including the filling patterns, processing effects, operation window, and micro-structure replication are investigated. The first part of this thesis presents the design concept, construction, process, and characteristics of the pneumatic impact micro-injection machine. The second part displays the flow visualization of filling a spiral cavity implemented with transparent window with aid of colored billets and high speed video camera during pneumatic impact micro-injection molding. The third part investigates the effects of processing conditions on the spiral flow using the pneumatic impact micro-injection molding machine. In the fourth part, test-sheet molds of different depths implemented with rapid mold heating/cooling system was constructed. The operation windows with various mold temperatures are defined for such impact micro-injection molding. The shrinkage and birefringence of molded parts are also studied. Finally, the molding of an optical component with feature of micro-lens array on surface was carried out. The effects of processing conditions on the quality of replication of microstructure are investigated and discussed.

The micro-injection molding machine can achieve an impact speed of 6500 mm/s. With the flow visualization facility observing the filling spiral cavity, the colored melt in the back soon take lead indicating that fountain flow is dominant. The flow length is deeper cavity is found longer, and the mold temperature significantly affects to the molding of thin part. The air pressure and hammer mass determines the impact energy and the filling process during impact micro-injection molding of spiral parts. From the molding of the test-sheets, it is found that thicker cavity and reasonably low mold temperature result in larger operation window. High mold temperature prevents short-shot, but causes serious shrinkage. From the molding of the optical components with micro-features, the micro lenses are found better replicated with high holding pressure, and are poorly replicated with high mold temperature and low holding pressure.

並列關鍵字

injection molding ； micro-injection molding ； impact type micro-injection molding ； pneumatic impact micro-injection molding ； flow visualization

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