Stereo-Lithography System for Fabricating Micro-Flexible Mechanism

本研究的目的是设计并建立一套光成形系统，通过引入中空表面控制，在树脂表面形成非常薄的液体层，用于微柔性结构的制造，主要研究成果如下：1.研究了自由液面的表面不均匀性和液面厚度。针对表面不平整的问题，提出了一种空洞控制方法.已经提出并研究了三种涉及空心控制的方法。在气压控制方法中，发现中空表面受到大气压力和温度变化的严重影响。现有的液量控制方法存在树脂罐与动盘摩擦、空槽响应滞后严重等问题。液面差控制方法克服了上述两种控制方法的缺点，易于实现.对空心结构的理论分析和数值模拟为喷嘴单元的设计提供了依据。设计并搭建了一套基于液面差控制的光刻实验系统.进行中空层厚度的检查。当中空部在接近7 μ m的距离处靠近平台时，中空部开始振动。这种现象限制了最小层厚度为7 μ m。已开始制作样品模型。首次将液体表面作为立体光刻系统的控制对象，成功地制作了微柔性悬臂梁零件。已经实现了7 μ m的层厚度。研究表明，空心面控制方法在获得非常薄的液体层和高的加工精度的有效性。

The objective of this research is to design and build a photo-forming system, which can create very thin liquid layers in resin surface for the fabrication of micro flexible structures by introducing a hollow surface control into the system.The results can be summarized as follows.1. Surface unevenness and layer thickness of free liquid surface were investigated. To solve the problem of surface unevenness, a hollow control method was proposed.2. Three approaches involving hollow control have been proposed and investigated. In the air pressure control approach, the hollow surface is found suffering severe influences from the change of atmospheric pressure and temperature. Liquid quantity control approach has the problems of the friction between the resin tank and the movable plate, and serious time delay of hollow response to stick adjusting. Liquid surface difference control approach has no the disadvantages of the above-mentioned two approaches and is easily realized.3. Theoretical analysis and numerical simulation of the hollow shape gave a ground for the design of the nozzle unit. An experimental photo-forming system based on liquid surface difference control approach is designed and built.4. Examination of hollow layer thickness is conducted. The hollow begins to vibrate when it closes to the platform at a distance of near to 7 mum. This phenomenon limits the minimum layer thickness to be 7 mum.5. Fabrication of sample models has been undertaken. A micro flexible cantilever part was successfully manufactured.This is the first time that the liquid surface has been treated as a subject of control in stereo-lithography systems. The layer thickness of 7 mum has been realized. This research shows the effectiveness of the hollow surface control approach on attaining very thin liquid layers and high processing accuracy.