快速原型製程之下料機構改善與雷射掃描參數優化

Improving Feeding Mechanism and Optimizing Laser scan parameters of Rapid Prototyping Process

劉耿良(Geng-Liang Liu)

指導教授 ： 湯華興 ； 嚴孝全

國立臺北科技大學/機電學院/製造科技研究所/碩士(2011年)

摘要

本文第一目的為設計定壓式下料機構，利用固定重量來加壓來改善定容式下料機構刮刀前方漿料堆積的問題。在1kg的配重下，以固定壓力施加於針筒，將漿料送至細縫式刮刀，以刮刀速度30 mm/s 及20mm/s來鋪設層厚為30 μm之生坯薄層，刮刀前方無明顯漿料堆積。定壓式下料機構在前端預留刮面可以適應鋪層時工作條件變動來自動調節流量。因本實驗室製程漿料皆含有硬度較高的陶瓷顆粒，因此以滾捲式矽膠薄膜來取代針筒的抽擠方式，可以避免管壁摩擦造成損傷。
新製程欲開發強度為900 MPa的氧化鋯工件。其製程係使用雷射掃描工件輪廓來燒失黏結劑，但不會使粉末噴發。如此，可使掃描線中的陶瓷粉不黏結，以利工件自生坯塊中取出。故本文第二目的為研究以CO2雷射燒失黏結劑之參數優化。實驗材料為0.2μm 氧化鋯陶瓷粉末、有機聚乙烯醇為主要黏結劑以及濃度25%戊二醛為交聯強化生坯。每一生坯薄層需要掃描兩次。可燒失黏結劑的最佳參數為第一次掃描功率7W、掃描速度40mm/s；第二次掃描功率12W、掃瞄速度80mm/s。清料深度為144μm。

關鍵字

雷射脫脂 ； 燒失 ； 氧化鋯 ； 戊二醛

並列摘要

The primary purpose of this paper is to design a constant-pressure slurry feeding mechanism. To eliminate the disadvantage of the constant-volume feeding mechanism, which induced the heap of slurry in front of the scraper, a mechanism generated a constant-pressure by a constant weight was developed. The syringe with a fixed pressure generated by 1kg weight delivered slurry to a slit scraper for casting layer with speed of 30 mm/s and 20mm/s. No heap of slurry was found in front of the scrape. At front end of the constant-volume feeding mechanism, a scrape surface was kept to automatically adjust the flow rate when the condition of layer casting changed. Because the ceramic particles contained in the slurry are hard, a rolling diaphragm made of silicon film to replace the syringe for avoiding damage caused by friction between cylinder wall and piston of the syringe.
The new process would be used to fabricate the zirconia workpieces with strength of 900 MPa. The process used laser scanning the contour of the workpiece to burn out the binder without ablation. Because the ceramic powder in the scanning line did not bind, the green workpiece was easy to be taken apart from the green block. Therefore, optimizing parameters of burn-out by CO2 was the second purpose of current study. 0.2μm zirconia ceramic powder was a structure material; polyvinyl alcohol was an organic binder, and glutaraldehyde (concentration of 25%) was ascross-linking to strengthen the green body. Each green had to be scanned twice. The optimal parameter combination for binder burn-out was power 7W, scanning speed 40mm/s for the first scanning, and power 12W, scanning speed 80mm/s the parameters for the second scanning. The depth of material removal was 144μm.

並列關鍵字

Constant-pressure ； Constant-volume ； Burn-out ； Zirconia ； Glutaraldehyde

參考文獻

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