Stereo-Lithography System for Fabricating Micro-Flexible Mechanism

本研究的目的是设计并建立一种光生成型系统，通过在该系统中引入中空表面控制，在树脂表面形成非常薄的液层，以用于制造微柔性结构。考察了自由液面的表面不平整度和液面厚度。针对表面不平整的问题，提出了一种中空控制方法。提出并研究了三种涉及中空控制的方法。在气压控制方法中，中空表面受到大气压力和温度变化的严重影响。液量控制方法存在树脂罐与移动板之间存在摩擦、中空响应滞后严重等问题。液面差控制方法没有上述两种方法的缺点，易于实现。中空形状的理论分析和数值模拟为喷管单元的设计提供了依据。设计并搭建了基于液面差控制方法的光成像实验系统。对空心层厚度进行了检测。当中空在接近7微米的距离靠近平台时，它开始振动。这一现象将最小层厚度限制在7微米。已经进行了样品模型的制作。成功地制造了微柔性悬臂梁零件，这是首次将液体表面作为立体光刻系统的控制对象。实现了7微米的层厚。研究表明，空心面控制方法在获得极薄液层和高加工精度方面是有效的。

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.