超音波輔助薄殼射出成形之流動性研究

Abstract

運用超音波振動進行輔助加工時，一般皆認為有降低工件變形阻力，減少介面間摩擦力以及提高工件溫度的效應，本研究則希望透過這些優點來改善薄殼塑膠射出成形所遭遇的材料流動性不良之情況。研究的方法是於模具嵌入一可振動的模仁形成一長直薄流路，材料流入薄流路的同時亦受到超音波振動之影響，再藉由取出之成品觀察超音波振動是否適合用於射出成形之加工。由實驗結果看來，超音波振動用於薄殼射出成形時，較高的模具溫度因材料的固化時間較長，超音波振動能讓成品有較大的增長量。推測此乃因超音波振動在材料固化前能降低其流動時所受的阻力。本文中亦討論了模具設計方法以及實際應用時所可能遭遇到之問題，並於本文最後提出幾項改進之建議，希望藉此增加超音波輔助射出成形之可行性進而對超音波應用於射出成形有所幫助。

While applying ultrasonic vibration to manufacture processes, it is generally recognized that it exhibits the effects of lowering the deformation resistance of workpiece, decreasing friction between contact interfaces and raising the temperature of the workpiece. In this research, we tried to utilize these advantages into thin-wall injection molding to overcome the poor flow properties of the material. A mold insert was designed into the moving-side of the mold, and while the material was being shooting into the thin-wall cavity, the mold insert start vibrating. By observing the appearance and measuring the length of the products, the effects of ultrasonic vibration to thin-wall injection molding were obtained. From experiment results, we found that the higher mold temperature leads to longer solidification time, and the longer solidification time leads to larger elongation of the products. Therefore, the ultrasonic vibration can decrease the flow resistance before the material getting solidified. In this thesis, we also discussed the ways to design a better mold and the problems that may occurred when putting ultrasonic assisted injection molding into practice. Some suggestions for increasing the feasibility of ultrasonic assisted injection molding were proposed at the end of this thesis. We hope they can be a great help to those who are interested in ultrasonic assisted injection molding.