模具內旋轉機構對射出成型之結合線強度影響

Abstract

本研究將針對結合線強度的問題進行實驗，由於結合線產生的原因主要是模具內有兩股以上熔融的塑料接合，如產品中有孔洞的設計或者模具有兩個以上的進膠點時會產生結合線。我們將一旋轉機構置於結合線位置，利用旋轉擾流的作用，將結合線位置的塑膠進行攪拌，達到攪亂結合線的效果，並調整旋轉機構的轉速與型式，與一般結合線的產品進行強度上的分析與比較。 實驗結果顯示，旋轉裝置確實有對產品的結合線達到攪拌的效果，外觀上可以很輕易的看出攪拌過的結合線狀況，與我們預期的現象相符合。在強度上，PC材質由於流動性較佳，對攪拌的效果影響較大，低轉速的強度較佳；ABS材料由於本身黏度較高流動性較差，對攪拌的效果較差，同樣的在低轉速下其抗拉強度較高轉速佳。

This study examines the effect of weld lines on the strength of injection mold. Weld lines typically occur when the flow fronts of two or more different plastics melt together during the injection process. Weld lines also result from use of molds designed to create a product with holes, or molds with multiple plastic injection gates. In this study, an in-mold rotational device was placed at the weld line. This added rotational disturbance facilitates the mixing of plastic materials at the weld line, effectively disrupting the structure of the polymers. Comparison was then made between the strength of the weld lines observed when using varying modes of rotation at different speeds, and the strength of typical weld lines. Experimental results show that rotational devices indeed result in disturbance of the weld line. Visual inspection shows an apparent effect of rotational disturbance on the state of the weld line, in accordance with expectations. In strengthening the weld lines of injection process when using polycarbonates (PC), due to a low viscosity and low resistance to disturbance, a low rotational speed is optimal in the disruption of weld lines. For a rigid substance with high viscosity such as acrylonitrile butadiene styrene (ABS), which is highly resistant to disturbance, a low rotational speed is also optimal because of the large amounts of tension involved.