DLP刮刀列印系統之探討

Abstract

光固化成型技術具有成品表面光滑、精度高、成型速度快等優勢，可用於快速印製微結構。光固化成型技術依照光源的位置又可分為上照式系統及下照式系統，其中上照式系統由於不需考慮拉拔力，因此較適用於微結構的成型。然而上照式系統需仰賴光敏樹脂自身的流動性填滿列印平台，當印製微結構時，每層切厚度皆為微米等級，樹脂無法流入列印範圍內，造成模型的底部無法順利固化，容易發生瑕疵。若嘗試在光敏樹脂內添加奈米碳管，印製奈米複合材料(Nanocomposite)，會使得樹脂的黏稠度進一步增加，導致完全無法使用上照式列印系統製造模型。 本研究開發出刮刀式系統以改善上照式系統的缺點，並測試刮刀式系統的曝光時間、切層厚度、樹脂調配等列印參數，藉由該系統成功印製出八隅體立體微結構以及含有奈米碳管的微結構。利用有限元素軟體分析八隅體結構受負載時的應力分布、破壞方式，最後探討刮刀式列印系統的技術限制，說明刮刀運作時對於微結構可能的破壞機制。

Vat photopolymerization has advnatages of smooth fabricated product surface, high precision, and fast manufacture. Vat photopolymerization can be used to fabricate free-form 3D microstructures. Vat photopolymerization can be divided into 'top-down' system and 'bottom-up' system according to the position of the light source. The 'top-down' is more suitable for the manufacture of microstructures because it does not need to consider the force of detachment movement at every layer. However, the 'top-down' system relies on the rheological properties of the photosensitive resin to coat the platform. When printing microstructures, the thickness of each layer is micron size, so the resin cannot coat the platform, resulting in defects at the bottom of the model. If carbon nanotubes are added to the photosensitive resin to print nanocomposite materials, the viscosity of the resin will increase, making it impossible to use the 'top-down' system to manufacture models. This study developed a recoating mechanism to improve the shortcomings of the 'top-down' system, and tested parameters such as exposure time, resin formulation, and layer thickness. The octet-truss lattice microstructure and nanocomposite microstructure were successfully fabricated by this system. The finite element method was used to analyze the stress distribution and failure position of the octet-truss lattice microstructure. Finally, the thesis studied on the technical limitations of the recoating mechanism and the possible ways in which the microstructure was damaged when the recoating mechanism was operating.