模內氣體反壓與動態模溫協同控制系統應用於超臨界微細發泡射出成型發泡控制及產品機械性質之研究

Study of Foaming Control and Part Mechanical Properties During Microcellular Injection Molding Process via a Mechanism of Gas Counter Pressure and Dynamic Mold Temperature Variation

蕭宇倫(Yu-Lun Hsiao)

指導教授 ： 陳夏宗

中原大學/工學院/機械工程研究所/碩士(2011年)

https://doi.org/10.6840/cycu201100648

摘要

超臨界微細發泡射出成型(Microcellular Injection Molding Process, MuCell) ，擁有節能省料、尺寸穩定性佳、流動性佳等許多優點，但MuCell成型品的表面缺陷使MuCell技術在產品的應用性下降。近年來關於MuCell成型所造成的表面缺陷已有許多解決方法而這些方法會改變MuCell成型品中的氣泡尺寸與分佈，而改善後成品之發泡品質與機械性質的影響性至今未被廣泛討論。本研究使用現今在MuCell表面品質改善較具成效的兩項技術，其一為模穴內氣體反壓(Gas Counter Pressure, GCP)機制；其二為動態模溫協同控制，分別透過壓力與模溫來控制熔膠中超臨界流體(Super Critical Fluid, SCF)的發泡過程和品質，最後將兩項技術同時應用於MuCell成型中，觀察各種改善方法對於發泡品質與機械性質的影響。
研究結果顯示，GCP對於控制氣泡、增加凝固層厚度較具效果，當凝固層厚度增加，拉伸強度也隨之提高，而衝擊強度則下降；動態模溫則對於氣泡尺寸增大與降低凝固層較為明顯，平均氣泡尺寸越大，拉伸強度下降越多，而衝擊強度在平均氣泡尺寸30μm以下無明顯增加，30μm ~ 80μm能有效增加衝擊強度，而在80μm以上衝擊強度隨著平均氣泡尺寸越大而降低。同時使用GCP與動態模溫控制，可使MuCell成型品中凝固層較GCP來的薄，而平均氣泡尺寸也較動態模溫來的小且均勻，這對拉伸與衝擊強度來說，皆可達到較佳的效用。以拉伸強度而言，獲得控制的氣泡會較動態模溫控制來的高出許多，在同一模溫下約提升10%；就衝擊強度來說，在同一GCP參數且平均氣泡尺寸佳的情況下，提高模溫可使凝固層變薄，這有助於提高衝擊強度。

關鍵字

超臨界微細發泡射出成型 ； 機械性質 ； 動態模溫 ； 氣體反壓

並列摘要

Microcellular injection molding (MuCell) offers many advantages such as material and energy saving, melt viscosity and warpage reduction, but the application of Mucell technology is not common due to the defects of surface quality. There are some new ways to improve the surface quality of Mucell molded part in recent years, but the mechanical properties still have not been widely discussed. The purpose of this study is to develop a foaming control by Gas Counter Pressure (GCP) combined with mold temperature control technology during MuCell process and to investigate its relevant influence on mechanical properties.
The results reveal that under GCP control alone, it can effectively influence the foam qualities and the thickness of Frozen layer, also increase the tensile strength but decrease the Impact strength; the lower the mold temperature control for the frozen layer, the more obvious bubble size increase; the greater the average bubble size, the lower the tensile strength is, and the impact strength does not increase until the average bubble size increase to 30μm ~80μm. The impact strength will decrease while average bubble size is bigger than 80μm.Using both GCP and dynamic mold temperature control, the thickness of the frozen layer is thinner than using GCP only, and the average bubble size is smaller and more uniform than using dynamic mold temperature control only. In this case both tensile strength and impact strength has a better performance. For tensile strength, the numbers of controlled bubbles would be 10% more than only using dynamic mold temperature control in the same mold temperature; for the impact strength, in the same parameters and the uniform bubble size GCP, the mold temperature can improve the thin solidified layer, which can improve the impact strength.

並列關鍵字

Mechanical Properties ； Surface Roughness ； Microcellular Injection Molding ； Mold Temperature Control ； Gas Counter Pressure

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