氣體反壓在共射成型上的探討與應用

Discussion applies Gas Counter Pressure of Co-Injection Molding

劉德緯(De-Wei Liu)

指導教授 ： 鍾文仁

中原大學/工學院/機械工程研究所/碩士(2016年)

https://doi.org/10.6840/cycu201600780

摘要

現今日常生活充滿各種塑膠產品，為了減少生產成本、提高產品強度、改善產品外觀與響應環保等要求，發展出了許多綠色成型技術，例如：氣輔、液輔以及共射成型等，其中共射成型又稱三明治成型，能以單一射出程序製造多層結構之複合塑膠產品，其製程是先將一定料量之皮層熔膠短射至模穴內，再射入核心熔膠將模穴填充完整，在業界通常利用回收二次料或是強度佳的塑料作為核心料，達到降低用料成本以及增強產品強度，或是透過適當的料量比例來減少殘留應力並增加機械強度與表面品質。
而本研究目的在共射成型過程加入氣體反壓技術來增強機械強度、減少殘留應力之分佈，因共射成型具有兩種熔膠的流動波前行為，皮層厚度分佈和核心穿透長度較難以控制，而核心熔膠也會因為噴泉流效應造成射出不穩定，因此本研究利用氣體反壓技術運用在共射成型上，來抑制流動波前行為，探討氣體反壓技術，對核心穿透效果和機械強度的影響，並透過不同氣體反壓大小，探討核心熔膠的穿透長度和穿透面積對於強度的影響。實驗結果顯示，加入氣體反壓機制能有效增加核心料穿透穩定性，改變核心料的穿透長度、穿透面積、減少殘留應力以及增強成品強度。

關鍵字

共射出成型、氣體反壓、機械強度、噴泉流效應

並列摘要

Today there are many types of daily products made by plastic. In order to reduce manufacturing costs, improve product strength and product appearance and to response environmental protection requirements, kinds of green molding techniques are developed, such as: gas-assisted, hydraulic auxiliary, and co-injection molding, etc. Co-injection molding is also known as sandwich molding. Co-injection molding is producing composite plastic product with multilayer structure in single injection. The process is to short shot the certain quantity plastic into the mold cavity, and then inject the core melt to complete cavity filling. In the industry recycled material or plastic with better strength are often as the core melt, so that to reduce costs and increase the product strength. Or decreasing the residual stress by the appropriate quantity in proportion, which also can increase the mechanical strength and surface quality.
In this study, we use the gas counter-pressure techniques to enhance the mechanical strength in co-injection molding process, also to reduce the residual stress distribution. Because there would be two different front waves in co-injection molding, cortical thickness and core penetration length are more difficult to control, but the core melt flow is instable due to fountain effect. Therefore, this study applied gas counter-pressure technology in the co-injection molding to suppress the wave front flow behavior. By controlling different amount of gas to discuss the effects of core melt penetration length and penetration area on product strength. Experimental results show that addition of gas counter pressure can effectively increase the penetration stability of the core melt, change the penetration length and area of the core melt, reduce the residual stress and increase product strength.

並列關鍵字

Co-injection molding, Gas Counter Pressure, Mechanical strength

參考文獻

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