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

本项目致力于开发一种新型的微非球面透镜、模具、反射镜等小型三维零件的加工方法。它正试图利用微细研磨和抛光工艺来加工小零件。用于传统加工工艺的钻石针头直径较小(0.1-1.0 mm)，但制造非常困难，刀具寿命变得很短。为解决这些问题，开发了一种新的现场辅助精加工方法。它被称为电流变(ER)流体辅助抛光。在这一过程中，抛光浆料是细磨料(金刚石、GC或WA)和电流变液的混合物。在针尖工具(正电极)和地电极(负电极)之间施加一个很强的电场(0-3KV/mm)。然后，电流变液的粘度增加，磨粒被轻轻地夹在工具尖端周围。在本实验中，通过ccd显微镜观察了聚集在刀尖周围的磨粒。很明显，每个磨粒都像一串珠子一样排成一条线相互连接，并随着电流变液向刀尖移动。在磨削和抛光小零件时，刀尖是作为一个非常小的砂轮执行的。设计并搭建了电流变液辅助抛光所需的检测仪器和控制系统。抛光机拥有3轴纳米定位工作台和超精密气轴。利用该抛光系统进行了基本的加工试验。抛光速度为20微米/15分钟。我们开发的电流变流体辅助抛光方法表现出了良好的抛光性能。这种方法不仅适用于制造工业微型设备的微尺寸光学元件，还适用于内窥镜等医疗用途的微非球面透镜，将在不久的将来得到广泛应用。

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.