BASIC STUDY OF ELECTRO REOLOGICAL FLUID ASSISTED ULTRA-PRECISION POLISHING FOR 3-DIMENSIONAL SMALL PARTS.

本计画系针对微小型非球面透镜、模具、镜面等三维小零件之加工方法进行研究。它试图利用微研磨和抛光工艺来加工小零件。用于常规加工工艺的金刚石套筒具有小直径（0.1-1.0mm），然而，套筒的制造非常困难并且工具寿命变短。针对这些问题，提出了一种新的光整加工方法--场辅助光整加工方法。它被称为电流变（ER）流体辅助抛光。在此工艺中，抛光液是细磨料（金刚石、GC或WA）和电流变液的混合物。强电场（0- 3 kV/mm）施加在非常锋利的工具如针（正电极）和接地电极（负电极）之间。然后，ER流体的粘度增加，并且磨粒被柔和地保持在工具的尖端周围。在本实验中，通过CCD显微镜观察聚集在工具尖端周围的磨粒。很明显，每个磨料颗粒彼此连接成一条线，就像一串珠子，并且随着ER流体朝向工具尖端移动。在研磨和抛光小零件时，工具尖端作为非常小的轮来执行。设计并搭建了电流变液辅助抛光所需的仪器和控制系统。该抛光机具有三轴纳米定位工作台和超精密空气主轴。使用该抛光系统，进行基本的加工试验。抛光速率为20 μ m/15 min。我们开发的电流变液辅助抛光方法表现出优异的抛光性能。该方法不仅适用于制造用于工业微型器件的微尺寸光学器件，而且适用于制造用于医疗应用（例如内窥镜）的微非球面透镜，其将在不久的将来被广泛使用。

This project deals with the development of a new machining method for small 3-demensional parts such as micro-aspherical lens, die and mirror. It is trying to machine the small parts utilizing a micro-grinding and polishing processes. A diamond quill for the conventional machining process has a small diameter (0.1-1.0mm), however manufacturing of the quill is very difficult and a tool life becomes short. A new method, which is one of field-assisted fine finishing methods, is developed to solve these problems. It is named an electro-reological (ER) fluid assisted polishing. In this process, polishing slurry is mixture of fine abrasive (diamond, GC or WA) and ER fluid. A strong electric field (0-3kV/mm) is applied between a very sharp tool like a needle (positive electrode) and a ground electrode (negative electrode). Then, viscosity of the ER fluid is increased, and the abrasive particles are softly hold around the tip of the tool. In this experiment, abrasive particles gathering around the tool tip are observed through a CCD microscope. It is clear that the each abrasive particle is connected with one another in a line like a string of beads, and moving with the ER fluid toward the tool tip. The tool tip is performed as a very small wheel in grinding and polishing the small parts. The necessary instrumentation and control system of the ER fluid assisted polishing have been designed and built. The polishing machine has a 3-axis nano-positioning table and an ultra-precision air spindle. Using this polishing system, basic machining tests were carried out. The polishing rate was 20mum/15min. The ER fluid assisted polishing method that we developed demonstrated excellent polishing performance. This method is applicable for manufacturing not only micro-size optics for industrial micro devices, but also micro-aspheric lens for medical applications such as an endoscope, which will be widely used in the near future.