| 摘要: | 金屬粉末射出成型(Metal Injection Molding, MIM)主要的優點為大量生產造形複雜之金屬產品，而且不需二次加工。異形水路近年因金屬積層製造(Metal Additive Manufacturing, MAM)技術的成熟而廣泛應於射出成型模具上，但相關研究之產品材料仍以塑膠為主。本研究為首次結合上述兩種技術，探討異形水路對MIM產品與模具之影響，並於水路設計階段，透過模流分析軟體Moldex3D進行驗證，評估異形水路效益。
本研究之異形水路與傳統2D水路的管徑分別為3mm與8mm。模流分析結果可以看出，冷卻液進點在相同流率的情況下，異形水路之模溫機需要較高的水泵壓力，流速與雷諾數也較高。異形水路及傳統2D水路之平均雷諾數分別為10825與20702，代表其冷卻液皆有達到紊流狀態。模具預熱階段異形水路模具僅需傳統2D水路模具7.17%的時間，就可加熱到指定溫度。由於本研究之MIM機搶卡榫為厚件，所以翹曲變形較不明顯，但從模流分析的結果看來，異形水路產品因模溫分布較均勻的關係，導致擁有較均勻的體積收縮，可減少2.36%的表面凹痕位移量。
本研究利用金屬3D列印製造異形水路模具之模仁，與傳統2D水路模具進行射出成型試驗。 透過紅外線熱影像儀拍攝證實異形水路可改善15.46%的母模仁溫度均勻性，在以模溫控制產品品質上可更有效率。在合適的冷卻液溫度下，異形水路可帶走更多的熱量，達到降模溫及縮短冷卻時間的效果。試驗之成型參數之冷卻時間，異形水路模具較傳統2D水路模具少3秒鐘，仍可順利生產產品，異形水路試模樣品之X、Y、Z尺寸差異與傳統2D水路樣品相當，證明異形水路模具在縮短成型週期的情況下，也能兼顧產品尺寸的精度。
;The major advantage of Metal Injection Molding (MIM) is able to produce complicated metal product without second process. Due to the technology of Metal Additive Manufacturing (MAM) is getting mature in recent years, makes the application of conformal cooling on injection mold more popular. However, the product material in related study is mainly plastic. This thesis is the first study combines the technologies mentioned above, and explores the effect of conformal cooling to MIM product and mold. Moreover, in the cooling channel design stage, injection simulation software - Moldex3D was used to verify the conformal cooling benefits.
The channel diameter of conformal cooling and conventional 2D cooling in this study, are 3mm and 8mm respectively. According to the simulation result, with same coolant flow rate at entrance, the conformal cooling requires higher pump pressure of temperature controller, and the coolant velocity and Reynolds number are higher as well. The average Reynolds number of conformal cooling and conventional 2D cooling are 10825 and 20702 respectively, means both coolant has achieved turbulent flow. In mold preheat stage, the mold with conformal cooling requires only 7.17% of duration to heat up to designated temperature compare to the mold with conventional 2D cooling. The MIM bolt catch in this study is a thick part, therefore the warpage is not obvious, but from the simulation result, conformal cooling product has more uniform mold temperature distribution, leads to more uniform volumetric shrinkage, and able to reduce 2.36% of sink mark displacement.
This study fabricated the core of conformal cooling mold by metal 3D printing, and applied injection molding trial together with the mold with conventional 2D cooling. According to the image of infrared thermal imaging camera, conformal cooling can improve 15.46% of cavity temperature uniformity, and gain more efficiency in product quality controlled by temperature. Under an appropriate coolant temperature, conformal cooling can remove more heat, and achieve the effects of reducing mold temperature and cooling time. The cooling time of the mold trial molding parameter, conformal cooling has 3 second less than conventional 2D cooling. In such condition, conformal cooling mold was still able to produce products, and the product X, Y, Z dimension difference compare to conventional 2D cooling product is close. The result proofs that, while the conformal cooling mold reduces cycle time, it can still ensures the product dimensional accuracy. |
