射出成型之縫(熔)合線探討及實務對策

Investigation Weld-line of Injection Process Investigation Weld-line of Injection Process And Application Countermeasure

林文卿(Wen-Ching Lin)

指導教授 ： 黃健生 ； 鍾文仁 ； 陳夏宗

中原大學/工學院/機械工程研究所/碩士(2005年)

https://doi.org/10.6840/cycu200500190

摘要

中文摘要
在這3C的時代裡，消費者對產品的外觀品質及安全舒適的要求已達極緻。因此塑膠製品及射出成型工業越來越重要，但是縫(熔)合線卻常常造成塑膠製品的缺陷與不良，故本文主要探討縫(熔)合線在實務上的完全解決對策，期望能夠改善或消除縫(熔)合線所造成的問題。
本文係利用比對分析法，並參考Kim和Suh所建立的高分子縫(熔)合線鍵結強度的理論模型，及以三十幾套”3C”產品之新的真實塑膠模具做局部的對策及驗證，並配合CAD及CAE 的軟體做模流分析。再以二套類似的模具做最後的比對及驗證。
本文中主要的對策是將塑膠製品的肉厚加大以減少流動波前的阻力，以改善熔膠合流部份的接合處之熔膠溫度，並且改進流道系統及改變進澆充填進入模腔內的時間，以改善模腔內的包風(封)現象，並避免熔膠合流部份的接合處之接合角度過小。
本文所得結果顯示，軟體模擬分析的結果與真實塑膠模具驗證的結果完全吻合，只要能夠避免熔膠流動產生分流或其分流之接合角度不可過小，並且提高熔膠合流部份之接合處的溫度及接合處不可有包風(封)的現象，即可使聚合物之分子在接合處的界面間完全自由的擴散，並且產生完全的鍵結，也就不會有縫(熔)合線發生。

關鍵字

縫合線 ； 熔合線

並列摘要

Abstract
In an era of this 3C generation, the consumer’s demands for the product quality of appearance, security and comfort ability have already reached a limit. Therefore, plastic products with the injection mold industry become more and more important. However, the weld line often causes defects in plastic products. This study mainly concentrates upon practical countermeasures for the weld line. Through this study, it is expected to improve and further resolve the problems caused by the weld line.
This study is to utilize the comparatively analytical approach with reference to the theoretical polymer strength of weld-line model, proposed by Kim & Suh, and do some countermeasure and verification with more than 30 real case studies, the CAE is used to mold flow analysis. At last, two similar molds were compared and verified.
The main countermeasure in this study is to add the thickness of the plastic product. It functions to reduce the obstruction of the flow front, to improve the temperature of the flow joint of melted polymer, to improve the runner system for time controlling of polymer into the mold cavity, consequently to improve the air trap condition in mold cavity, and further to avoid the melted polymer joint’s angle too small.
The study shows that the computational simulated results are quite agreement with the real cases. It can be concluded the polymer molecules can fulfill the totally free diffusion among joint boundaries and perfect bonding by preventing the melt flow from diverging and its joint angle too small, elevating joint’s temperature, and/or keeping air trap from the melt joint. As a consequence, the weld line will not occur.

並列關鍵字

Weldline ； Weld-line

參考文獻

8. 鍾明修,”ABS薄殼射出成型件縫合線之探討”, 中原大學碩士論文,

64. Moldflow Advanced Training (MPI 3.0)(綺城科技股份有限公司)。

76. 伍全企業股份有限公司(http://www.tohatsu.com.tw/)

1. S. G. Kim and N. P. Suh,”Preformance Prediction of Weldine Structure in Amorphous olpmers”, Polymer Engineering and Science, Vol. 26, No. 17, (September 1986)。

2. S.Y. Guo and A. Ait-Kadi,”A study on weld line morphology and mechanical strength of injection molded polystyrene/poly(methyl methacrylate) blends”,Journal of Applied Polymer Science, Vol. 84, No. 10 pp. 1856-1865, ( June 2002)。