微快速原型系統之霧化鋪層技術改良

The Improvement of Spray Coating Technology Used in Micro Rapid Prototyping System

洪常益(Ching-Yi Hung)

指導教授 ： 汪家昌

國立臺北科技大學/機電學院/製造科技研究所/碩士(2007年)

https://doi.org/10.6841/NTUT.2007.00338

摘要

細微化高解析度的3D工件已成為目前快速原型機設計與製造的主流，而目前商業化之液態快速原型系統中，切層之厚度常是系統之關鍵技術，鋪層系統鋪過工件表面時，較薄鋪層將容易受到鋪層系統所產生的剪切力破壞，製作微小工件時，太多的支撐結構將難以去除，除此外鋪層系統也易因樹脂污染造成成品精度誤差。因此Micro RP以霧化鋪層是必要的，除了能減少支撐還能免除鋪層時之剪力降低層厚。
本篇研究主旨是改良微快速原型之霧化鋪層技術，之前的研究中魏宏樺以添加氯仿於光硬化樹脂中降低黏度，成功的達到霧化鋪層，但卻導致樹脂變質，在其實驗中驗證了50μm的層厚；嚴志豪以加熱加壓霧化法將層厚降至28μm的層厚。本研究以解決加熱霧化法於長時間操作造成樹脂因熱集中硬化變質，及減低重複加熱造成樹脂性質改變之問題，以高壓之單流體噴嘴，將樹脂施以高壓於常溫正常霧化，並將層厚再減少至20μm以下為目標，以達適用於微快速原型系統之目的。
本論文在研究的過程中，探尋各種可讓樹脂於常溫霧化的霧化技術，並從中尋找出適用於本系統之霧化方式，研究結果以液體壓力轉換方式將樹脂產生高壓使其其霧化，並尋找適合使用之自動化噴槍與高壓用噴頭對樹脂成功霧化鋪層至5μm之厚度，本論文最後結合於實驗室中之微快速原型實驗機，實際霧化量測來證明霧化鋪層技術的可行性，並用於各種微小3D工件之加工，更進一步的將此研究推近商業化之路。

關鍵字

微快速原型 ； 霧化鋪層

並列摘要

The subject of this research is to improve spray coating technology which applies in the RP (Rapid Prototyping) System. In Hong-hwa Wei’s study, [1] the chloroform has been added into photopolymer resin to decrease its viscosity and successfully build up an average level of 50 μm thickness spray coating layer. Although the resin-chloroform mixture can be successfully atomized and sprayed, the properties of resin were changed due to the chemical polymerization effect. On the other hand, Chi-hao Yen [2] adopted high pressure single phase spraying method. Chi-hao Yen made a test to heat up the photopolymer resin to decrease its viscosity. The resin was atomized under high pressure status and successfully decreased the thickness of coating layer to an average level of 28 μm. However, the heat transfer effect and the duration of heating process in Yen’s method could bring the resin to its glass transition temperature. Meanwhile, the repeat-heating procedure changes the resin’s properties as well.
The objective of this research is to atomize photopolymer resin under room temperature by using high pressure single phase spraying method and try to decrease the thickness of coating layer to 20μm. Since the design and manufacturing ability of micro-size, high resolution prototype has become the main stream of RP system; each RP system manufacturer owns their unique expertise. In the field of commercial liquid based RP system, how to control the thickness of RP layer has become the key point of system engineering. The conventional liquid based RP system employs a special designed recoat to scrape resin from one side of the tank to the other to ensure surface flatness. However, the conventional design is easy to cause surface damage, which is resulted from the shear force, when building up a working part with higher resolution (with thinner layer). The conventional liquid based RP system also makes it difficult to remove support structures, especially building up micro size working part. Besides, the scraping procedure is easy to bring extra resin which comes with negative effect on working part accuracy. Therefore, it is necessary to apply spray coating technology on Micro RP system. Not only reduce the necessary support structure, but also reduce the RP layer thickness.
A spray technology which could atomize photopolymer resin in room temperature will be discussed in this research. The spray technology will apply to the new proto type liquid based RP system. The result of this research will utilize liquid-pressure-conversion method to atomize resin liquid under high pressure status. The automatic mechanical spray gun with a TG0.3 spray nozzle made for this research successfully atomize the photopolymer resin and form a 5μm thickness resin coating. In the last phase of this research, a micro-size three dimensional working part were fabricated to test and verify the possibility of spray coating technology. The results of this research will integrated in the prototype of spray coating system which can be employed in the manufacturing of variety of micro size working part.

並列關鍵字

Micro Rapid Prototyping ； Spray coating

參考文獻

[3] 嚴志豪，微快速原型系統之霧化鋪層技術改良，碩士論文，國立台北科技大學，台北市，2006。

[1] 謝明哲，動態光罩微快速原型系統開發，碩士論文，國立台北科技大學，台北市，2004。

[2] 魏宏樺，微快速原型系統之霧化鋪層技術研究，碩士論文，國立台北科技大學，台北市，2005。

[16] C.H. Lee, Rolf D. Reitz, “An experimental study of the effect of gas density on the distortion and breakup mechanism of dropsin high speed gas stream”,International Journal of Multiphase Flow 26(2000) 229-244.

[4] CHUA CHEE KAI, LEONG KAH FAI, Rapid Prototyping: Principles & Applications in Manufacturing, June 1996,pp.17~pp.18