超音波輔助射出成型製程探討

Study of Ultrasonic Injection Molding

枋定緯(Ting-Wei Fang)

指導教授 ： 楊申語

國立臺灣大學/工學院/機械工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.03482

摘要

本研究利用加裝於模具澆道內的超音波振盪子，在射出成型過程中以頻率19 kHz對Polycarbonate (PC) 融膠進行超音波振盪，觀察超音波輔助射出對融膠在平板件與微結構件的填充保壓行為及微結構複製性的影響。
本研究第一部分使用平板試片，利用1.0 mm與0.5 mm厚度的平板試片射出短射件，研究超音波輔助射出成型的填充行為。實驗結果發現，1 mm厚度的平板試片在不同的製程參數下，有超音波輔助射出的試片長度與重量，皆有不等幅度的增加。在薄件(0.5 mm厚度)射出成型方面也有小幅度效果提升，但輔助效果不及厚件。本研究也針對澆口封閉時間延遲的效果與超音波振幅的影響進行實驗，實驗結果發現超音波輔助射出成型可使澆口封閉時間延遲，讓保壓補縮效果更佳；但振幅也需要大於一定幅度，其輔助效果才會明顯。在殘留應力方面，本研究未發現殘留應力大幅下降，也許受限於本實驗之超音波振盪的位置、方向、能量。
本研究第二部份使用有表面V溝微結構1 mm厚的板件，實驗結果發現超音波輔助射出成型能有效提升結構轉寫率，在三種不同製程參數(射出速度、保壓壓力、模具溫度)的交叉比對下，微結構轉寫率都有得到不等幅度的提升，在較低的保壓壓力時也能得到相當不錯的結構轉寫率。
本研究證實超音波輔助射出成型對塑料在平板與V溝微結構件填充流動有提升效果，驗證了超音波輔助對融膠填充力正面的輔助效果，有潛力可用於克服射出成型在製作特殊精密光電元件時，所遇到短射、微結構填充不足等製程上的困難。

關鍵字

超音波輔助射出成型 ； 塑料填充性 ； 微結構成型

並列摘要

This research is devoted to investigating the effects of ultrasonic vibration in the filling and packing behaviors of the Polycarbonate (PC) melt in flat plates and plates with microstructures.
First, with and without ultrasonic vibration, the filling behaviors of PC melt in the cavities of flat plates of 1.0 mm and 0.5 mm thick with aid of short-shots. This study discovered that the length and weights of short-shots in filling the 1mm-thick cavities increased with ultrasonic vibration, compared to these without ultrasound. On the other hand, little improvements were observed in the filling of the thin-wall parts of 0.5 mm thick. The effects ultrasonic vibration in extending the gate freeze time were systematically investigated. Ultrasonic vibration could significantly prolongs the gate freeze time and extends the packing process. It was found that the amplitude of ultrasonic vibration must exceed a particular level for the effect of ultrasonic vibration to be significant. The ultrasonic vibration in this study showed no effects in reducing residual stress. This maybe due to the limit of our facility and implementation.
In the other part of this research, the replication of V-groove microstructures in the plates of 1 mm thick were also investigated. It was found that ultrasonic vibration improves replication of microstructrues. The effects of vibration in injection molding with different injection speeds, packing pressures and mold temperatures have been studied. The improvements in enhancing the degree of replication are significant, especially at low packing pressure.
This study demonstrates that ultrasonic vibration improves the filling and packing of flat and v-grooved plates, showing the potential of using the ultrasonic vibration in enhancing the molding capacity of injection molding.

並列關鍵字

Ultrasonic injection molding ； Filling behavior ； Microstructures

參考文獻

[2] 鄧高生，王俊欽，”非球面模造鏡片製造技術”，光學工程，第49 期，pp.35-39，(1995)

[1] J. Greener, “General Consequences of the Packing Phase in Injection Molding”, Polymer Engineering and Science, Vol.26, No.12, pp.886 -892, (1986)

[4] Jansen, K. M. B., Van Dijk, D. J. and Husselman M. H. “Effect of Processing Conditions on Shrinkage in Injection Molding”, Polymer Engineering and Science 38,5,838-846(1998)

[6] Pham, “Residual Stresses in Injection Molded Polycarbonate Rectangular Bars”, Polymer Engineering and Science , Vol.33, No.24, (1993)

[7] A. Siegmann , “ Residual Stresses in Injection-Molded Amorphous Polymers” , Polymer Engineering and Science , Vol.27, No.14 ,p1069, (1987)