Research On Fine Machining Using Instantaneous Tiny Grinding Wheel Based On ER Effect And Design Of ER And MR Fluid-assisted Ultra-precision Polishing Installation

As a type of smart function material, Electrorheological(ER) fluids exhibit the peculiar rheological characteristic that is induced by the electric field. In the presence of electric field, ER fluids' apparent viscosity and yield strength will increase rapidly and its property is similar to the solid property. In our research, particle-dispersed ER fluid is used as a special instantaneous bond to cohere abrasive particles in the ER fluid so as to form dynamical tiny grinding wheel in grinding for fine machining. Thus, when abrasive particles is put into the ER fluid and electric power is supplied such that the needle-like tool is cathode and the workpiece is anode, one end of the electric force lines will converge on the tip of the tool and the other end of the electric force lines will be an emissive shape. The abrasive particles are banded in the ER particles and this time a tiny wheel is formed. When the tool rotates, the abrasive particles rotate as well leading to a grinding effect.At first, the capability and the mechanism of ER fluid are analyzed. Then the electric field intensity of tool-tip is analyzed to optimize the shape of tool-tip. The new machining method using instantaneous tiny grinding wheel based on ER effect for fine machining on micro apparatus with rigid-fragile materials was researched. New ER fluid is confected. Experiments have been carried out by using SEM to analyze the characteristics of processed workpiece surface. By regulating some parameters such as voltage, ingredient of ER fluid, material of tool electrode, machining time etc, the size, rigidity, and abrasive mutual combine-intensity of the micro grinding wheel can be controlled in order to achieve an expected machining effect. The experimental results show that the shape of too-tip decides the distribution of electric field intensity on tool-tip so that the structure and grinding property of dynamic tiny grinding wheel are decided. The optimization of component of ER fluid is an effective way to improve the machining effect. Material and abrasive resistance of tool electrode affects observably material removal rate in the process. Abrasive resistance of tool electrode decides retentivity of the gap between the tool and workpiece so that polishing pressure between micro grinding wheel and workpiece is retainability and material removal rate is affected.An installation which can be used for the machining micro apparatus base on ER and magnetorheological(MR) fluid-assisted ultra-precision polishing installation is designed and manufactured. It contains 3 liner motion systems and 1 turning systems. It can machining work piece with ER fluid-assisted polishing or MR fluid-assisted polishing or ER and MR fluid-assisted polishing. The structure of installation is optimized. The control system for the installation is developed. The motion systems are controlled by motion card. Through input machining code to the control software, all the movements of the installation can be controlled by the computer to let workpiece and tool electrode move. The experiment shows the installation has good stability and flexibility.