多段氣體反壓應用於超臨界微細發泡射出成型泡體均勻性之研究

Study of Foaming Uniformity During Microcellular Injection Molding of Multi-Stage Gas Counter Pressure

李沈濰(Shen-Wei Lee)

指導教授 ： 陳夏宗

中原大學/工學院/機械工程研究所/碩士(2020年)

https://doi.org/10.6840/cycu202000222

摘要

超臨界微細發泡射出成型製程(Microcellular Injection Molding, MuCell®)為現今塑膠產業中，具有優越發展性的綠色成型技術之一，其優勢具備環境友善、節省能源、降低成本、縮短成型週期等等，因此於各式領域中皆被廣泛應用，然而在MuCell®製程中，所面臨最大的問題為泡體均勻性差，進而造成產品性能降低。過往研究顯示同為綠色成型技術之一的氣體反壓控制技術(Gas Counter Pressure, GCP)，能有效控制充填過程中的發泡行為，但應用於產品形狀複雜且厚度不一時，仍然在泡體均勻性上會有些差異，因此，本研究期望探討不同厚度下所需之反壓控制壓力，並且針對非均一厚度之產品建立一種多段氣體反壓機制，促使泡體均勻性達到進一步的提升，並於研究期間藉由觀察泡體平均直徑、泡體密度、泡體直徑標準差進行實驗比較與定義。
研究結果顯示，不同厚度模型適當之反壓持壓時間為充填結束時立即洩壓，並且隨著模型厚度變厚，充填時間會相對增加，因此需加長反壓持壓時間，才能夠控制充填過程中泡體的生長；不同厚度模型適當之反壓壓力隨著厚度變厚而增大，因厚度改變會使充填過程中模穴內壓力產生變化，進而影響到控制發泡所需之反壓壓力大小。最後以多段氣體反壓機制應用於多重厚度的模型時，相較於傳統氣體反壓，泡體密度提升約15%，且泡體直徑標準差從12.30µm降低至1.67µm，實現泡體均勻度提升之效果。

關鍵字

超臨界微細發泡射出成型 ； 多段氣體反壓機制 ； 泡體均勻度 ； 氣體反壓參數 ； 厚度不均模型

並列摘要

Microcellular Injection Molding (MuCell®) is one of the green molding technologies with superior development of today's plastics industry. It’s advantages including environment friendly, saves energy, reduces costs, shortens molding cycles, etc., which was used widely in various fields. However, there is a big problem of MuCell® which affects the performance of the product is cell uniformity. In past literatures have shown that Gas Counter Pressure (GCP), which is also one of the green molding technologies can control the foaming behavior more effectively during the filling. Although, there have slight difference of cell uniformity in different part thickness. Therefore, this study expects to investigate the required GCP control pressure at different thicknesses. Expecting to establish a Multi-Stage GCP mechanism for products with non-uniform thickness to further improve the uniformity of the bubbles. During the study, experimental comparison and definition will be carried out by observing the average diameter of the cells, the density of the cells, and the standard deviation of the cell diameter.
The result shows that the appropriate holding time for different thickness must release pressure at the end of filling immediately. As the thickness increases, the holding time is extended to control the cell growth because the filling stage increases. Otherwise the appropriate GCP pressure of different part thickness models are proportional to the product thickness. Owing to the different part thickness will cause the cavity pressure change during the filling stage, which will affect the amount of GCP pressure that required to control foaming. Finally, applied both Multi-Stage GCP control and traditional control to the multiplex part.
The part control by the Multi-Stage GCP which the cell density is increased by 15% and the standard deviation of cell diameter is reduced from 12.30µm to 1.67µm.

並列關鍵字

Microcellular Injection Molding ； Multi-Stage GCP ； Cell Uniformity ； GCP Parameter ； Uneven Thickness Product

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