Research Of Electrochemical Micro Machining Technology With Static Voltage

Electrochemical micromachining(ECM) is a technology that can machine a variety of microstructures. ECM uses a tool electrode in micro scale, combining with multi-axis numerical control system. The principle of machining is metal dissolution in the electrochemical reaction. ECM is an electrochemical dissolution machine that has many advantages such as no cutting force, no tool wear, no deformation and no material hardening restriction. Thus ECM has gradually become one of the main methods for machining the micro devices in micro-electro-mechanical system(MEMS). The technology has broad application prospects in the field of aerospace industry, precision instrument, biomedicaldomain, and so on.The accuracy of ECM technology mainly depends on the accuracy of nanosecond pulse power supply,butthe cost is really high. Those problems have become the bottleneck of achieving high precision with low cost. In this paper, the ECM using vibrating tool electrode and the ECM with small gap are proposed,those methods are avoid using nanosecond pulse power supply. Through the theoretical researches and the experiments of optimizing parameters, high level of machining accuracy and machiningstability are obtained without using a pulsed power supply.An ECM system with high accuracy, good stability and complete function is developed. This system has the following characteristics, such as good stiffness, precision clamping device of cathode and anode, perfect macro-micro motion control and machining detection system. Aim at the two method of using vibrating tool electrode and small gap in this paper. Vibration excitation mechanism with simple structure is designed. The control program that can limit current is compiled. According to this experimental platform, the method of tool setting and the basic procedure of processing micro pore, micro groove and micro structure are formulated.The device of fabricating tool electrode is designed. The technologies of fabricating multi-stepped tool electrode, the ultra flat tool electrode and the ultrafine tungstenwire pole are researched. In order to increase the bending stiffness of tool electrode.the parameter of fabricating multi-stepped tool electrode is researched. the ultra flat tool electrode and the ultrafine tungstenwire poleare fabricated after improving the device of fabricating tool electrode.The driving principle and control mechanism of vibration excitation mechanism are analysed. Through establishing the dynamic model of vibration excitation mechanism, the natural frequency and mode function are solved, and the structural parameters and material selection are determined. The finite element analysis of vibration excitation mechanism is completed, and the frequency of excitation voltage is obtained. The vibration mode and amplitude of vibration excitation mechanism in different parameters are analyzed. Through the coupling analysis of the vibration and electric potential difference in the electric double layer, the rule of voltage between two electrodes is obtained. Based on the diffusion current intensity equation, the vibration tool electrode can effectively improve the diffusion current intensityis verified. After comparative tests, the improvement of machining accuracy by using vibrating tool electrode is verified. Based on the voltage amplitude distance effect of the double layers under small separation, a novel electrochemical micromachining technique is proposed: it is static voltage-small separation electrochemical micromachining technique.Based on the voltage amplitude distance effect of the double layers under small separation, a novel electrochemical micromachining technique is proposed: it is static voltage-small separation electrochemical micromachining technique.Using the control program which can set current limit, the parameters such as current limit, voltage, feed speed, electrolyte concentration and tool electrode diameter are optimized by contrast tests. Some improvement measures are introduced, such as tool electrode with reciprocating feed, adding additive to electrolyte and accessing to reverse current. On the premise of ensuring machining capacity of the ECM with small gapin static voltage, the machining accuracy increased to the level of the ECM using a pulsed power supply. and the side gap of micro hole machining by the ECM with small gap in static voltage can reach the nanometer level.The method of keeping small gap is used in micro electrochemical milling(MECM). Through the contrast test, the parameters such as current limit, voltage, feedspeed, electrolyte concentration and milling layer thickness are optimized. The side gap of micro groove machined by the MECM with small gap in static voltage can reach only 1μm. And the micro structures such as micro cantilever beam, micro bentcantilever beamand micro circular cantileverbeamaremachined.