塑膠成型話機其外觀缺陷及實體落下測試之研究

Study of the Appearance Defect and Drop Test Performance of Injection Molded Handset with Snap Design

劉子維(Zih-Wei Liou)

指導教授 ： 陳夏宗

中原大學/工學院/機械工程研究所/碩士(2010年)

https://doi.org/10.6840/cycu201000105

摘要

中文摘要
本研究主要係以現有之卡勾設計結合之話機聽筒（Handset）為主體，針對其卡勾(Snap)結構處所造成之素材外觀明顯應力痕(Stress Mark)之缺陷，重新開立一套新模具改善此問題，基於現有產品已通過實體落下測試(Drop Test)且新模具成品仍須通過實體落下測試之考量，實驗中將沿用原聽筒Pro/Engineer 3D圖檔之內外耳卡勾結合型式、移除原聽筒內側供卡勾結合定位之凹槽、增加卡勾本身長度及加強肋（Rib）來增強整體卡勾強度，並進行MoldFlow模流分析（MoldFlow充填末端產品表面溫度差異、產品表面凹陷指標及體積收縮率之分析）以模擬新卡勾結構之聽筒其應力痕改善之情形，其中再探討不同材料溫度、模具溫度、進澆點型態、冷卻水路、模穴對稱式及非稱式排列等不同射出成型參數對成品外觀缺陷影響之MoldFlow分析（MoldFlow包風缺陷、充填末端產品表面壓力、溫度差異及綜合因素整體偏差分析），藉以求得最佳之模具設計及射出成型參數並進行新模具之開立，最後再實際進行新聽筒之落下測試及外觀應力痕改善情形之評判。
由Moldflow實驗結果顯示，新卡勾結構的確可有效改善應力痕之缺陷；另，最佳之射出成型參數為料溫275oC、模溫80 oC、牛角（Banana）式進澆口及10條水路之冷卻系統，可有效將產品表面各點之壓力、溫度差異及外觀缺陷減至最小；除此之外，兩模穴之排列方式以對稱式排列可得到最佳且兩穴品質一致之成品。
至於新模具成品之實體落下測試方面，新卡勾結構之聽筒仍保有舊聽筒卡勾之強力結合特性，且順利通過落下測試之驗證；另於新舊聽筒之外觀評判中可知，新卡勾結構可大幅改善舊聽筒外觀之應力痕，尤以未噴漆之素材最為明顯，且新卡勾設計之聽筒僅需一道噴漆製程即可遮蓋原應力痕之缺陷，達出貨之A級面標準，與舊聽筒所需兩道噴漆製程才能達出貨標準相較之下，可有效降低整體產品成本，增加產品市場之競爭性。

關鍵字

落地測試 ； 外觀缺陷 ； 射出成型 ； 模流分析

並列摘要

Abstract
In this research, the obvious stress mark defect on VoIP unpainted Handset caused by the strong snap mechanism structure will be improved with new tooling creation, consideration about the drop test reliability passed with the original Handset, it will keep the same snap type for the new tooling, and fill the dent area for the clip snap-in from the original snap design, then increase the clips length, with adding enhanced ribs behind clips to perform strong snap connection properties, with MoldFlow analysis to identify the stress mark improvement, furthermore, applying different injection parameters, such as Material & Mold Temperature, Gate Type, Cooling System and Symmetric & Unsymmetrical Orientation for Two Cavities, with MoldFlow analysis(Temperature Difference at the End of Filling, Sink Index and the Variation Volumetric Shrinkage Analysis) to find out the best condition for the new tooling. Finally, to validate the new handset with drop test reliability test, also with stress mark appearance comparison with the original handset.
The experimental results showed that, the new snap mechanism can indeed improve the stress mark defect on handset appearance, also the best injection conditions for the new tooling was Material Temperature 275 oC, Mold Temperature 80 oC, Banana Gate with 10 Water Circuits & 2 baffles, it can have the slightest defect and consistence on handset appearance. With the symmetric orientation design for two cavities, it can have two similar best quality handsets ever after.
On the drop test reliability test with the new handset, it shows the new snap mechanism also has strong connection properties which can meet our requirement, moreover, it can lighten the stress mark extent to compare with original handsets, and meet the appearance standard A with only 1 painting process, save the cost effectively.
Therefore, the new snap mechanism can improve the stress mark defect effectively, and keep the strong connection ability at the same time, also, the Moldflow Analysis results was quite similar to the real product injected from the new tooling.

並列關鍵字

Drop test ； Appearance defects ； Injection molding ； CAE

參考文獻

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