| The research and current application situation of micro-structure in the field of tribology and micro-machine are introduced in this paper. Micro-USM (Ultrasonic Machining), micro-ECM (electrochemical machining), micro-EDM (electrical discharged machining) and ultrasonic combined electro machining technologies and current status are summarized. Some fundamental research of ultrasonic combined micro-EDM and micro-ECM are carried out. The paper tries to study a precise, efficient and low-cost new technology for the micro-structure machining.The basic principle, characteristic and technology limitations of micro-USM, micro-EDM, micro-ECM and PECM (Pulse Electrochemical Machining) are analyzed. The mechanism of ultrasonic combined micro-EDM, micro-ECM are discussed. Micro-EDM, micro-ECM process state influence of ultrasonic vibration is researched. The technique advantage of the ultrasonic combined electric micro-machining are demonstrated on the mechanism.The ultrasonic combined electric micro-machining systems are built and improved. Ultrasonic device uses piezoelectric transducer and digital ultrasonic generator, which can be automated feedback and track the natural frequency changes of ultrasonic processing system, so processing in the resonant frequency of system which is the maximum amplitude of ultrasonic vibration. Adjustable magnetic tension bench with creep feeding mechanism is used to maintain optimal working pressure. Ultrasonic synchronous chopper is designed and manufactured, which can achieve ultrasonic vibration and synchronous of PECM. The machining accuracy is improved.Micromachining tool electrode is very small; its request of accuracy is very high, so the design and manufacture of micro-tool electrode is one of the key technology and difficulty in combined micro-machining. Many different shapes of tool electrode are designed, such as shaft, groove, rib, micro-convex array, micro gear. The manufacturing methods of micro-tool electrode are studied and perfected, such as WEDM (Wire Electric Discharge Machining), EDM"copy adding translate", combinative EDM, etc. With these means, several different micro-tools are successfully manufactured which are suitable for the request of ultrasonic combined electrical micro-machining.Many experiments are carried by USM on different materials such as kentaniums, stainless steel, monocrystal line silicon, piezoceramics, and glass with different micro-tools. Then compared tests by single ultrasonic machining and ultrasonic combined electrical micro-machining in different materials are done. Several parameters (such as pulse voltage, the quality percentage of electrolyte, etc) contrast test of ultrasonic vibration combined PECM are carried. The processing parameters are optimized, then the preliminary test of ultrasonic vibration combined synchronous PECM is carried. Tribological tests are carried with the surface micro-structure. The test results indicate, micro-USM is an effective method for machining hard and brittle non-metal, but the working efficiency of machining hard and tough metals is very low, and the wastage of machining tool is big. But, the Ultrasonic vibration combined electrical micro-machining has high working efficiency, good surface quality; furthermore, its micro-tool-cathode wastage is low. While Ultrasonic vibration combined synchronous PECM not only has high working efficiency, but also has better machining accuracy and surface quality. Design of auxiliary electrode, the use of micro-electrolysis, EDM combined machining of non-conductive materials is feasible. The friction surfaces with regular profiles micro-structures can store more oil and form oil film, which can reduce friction factor and wearing capacity compared to machine plane.In the end, the process technology of Ultrasonic combined electrical micro-machining is analyzed and summarized. Furthermore, process problems, shortage and its improvement means are also suggested. Then further study works are put forward. |
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