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

本课题主要研究微非球面、模具、反射镜等小型三维零件的加工新方法。它正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羽管直径较小（0.1-1.0mm），但制造难度大，刀具寿命短。为了解决这些问题，提出了一种新的现场辅助精加工方法。它被命名为电流变（ER）流体辅助抛光。在这个过程中，抛光浆是细磨料（金刚石，GC或WA）和ER流体的混合物。一个强电场（0-3kV/mm）在一个非常锋利的工具，如针（正极）和一个接地电极（负极）之间施加。然后，增加电流变流体的粘度，并将磨料颗粒轻轻地保持在工具尖端周围。在本实验中，通过CCD显微镜观察到磨料颗粒聚集在刀尖周围。很明显，每个磨料颗粒彼此连接成一条线，就像一串珠子，并随着ER流体向工具尖端移动。在对小零件进行研磨和抛光时，刀尖就像一个非常小的轮子。设计并搭建了电液辅助抛光所需的仪器和控制系统。抛光机采用三轴纳米定位工作台和超精密空气主轴。利用该抛光系统进行了基本的加工试验。抛光速度为20mum/15min。我们开发的ER流体辅助抛光方法具有优异的抛光性能。该方法不仅适用于制造工业微器件的微尺寸光学元件，也适用于内窥镜等医疗应用的微非球面透镜，在不久的将来将得到广泛应用。

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.