| The array micro-pits with regular profiles can modify surface tribology character, improve lubrication and wear-resisting. As the manufacturing methods are few, the research and current application situation of micro-pits on working surface between friction pairs are introduced in this paper. Ultrasonic combined micro-machining is proposed as a new technology, and then content and research significance of this paper are confirmed.Besides, the principle, working characteristic, realization condition and technologic property of USM, EDM and ECM are analyzed. The processing of impulsive discharge and micro-electrochemical can be improved by ultrasonic vibration. Then the mechanism and technical superiority of ultrasonic combined electrical discharge micro-machining are studied, as well as ultrasonic combined electrochemical micro-machining. At last, systems of ultrasonic combined electrical discharge micro-machining and ultrasonic combined electrochemical micro-machining are completed.In addition, the manufacturing process of micro-protrudes is a key for the micro-pits machining on working surface between friction pairs. At first, general principle of micro-pits design is raised due to the tribology theory; square and rhombus micro-pits are expended, based on the shape of cylinder. Then array micro-protrudes of cylinder, square and rhombus are designed. Micro-protrudes are machined by several combined electrical machining as WEDM, EDM"copy and shake", etc. With these means, different micro-protrudes are made and the general means are summarized.Working parameters like working fluid, oscillation frequency of tool electrodes, contact pressure are chosen according to analysing of processing systems, experiment scheme are presented. Single process experiments of ultrasonic machining of micro-pits are carried on cemented carbide(YT15, YG8), stainless steel, monocrystal line silicon, PZT, glass steel with different tool electrodes; contrast tests between single ultrasonic machining and ultrasonic combined machining are carried on kentaniums and stainless steel. Machining efficiency and precision of micro-pits on working surface between friction pairs as well as waster of tool electrodes influenced by electrolysis voltage amplitude and impulse frequency are mainly discussed. The feasibility of the ultrasonic combined micro-machining of micro-pits used in machining kentaniums and stainless steel is confirmed. At last, tribology test of micro-pits indicate that the structure of micro-pits can store more oil and form oil film, also it can reduce friction factor and wearing capacity compared to machine plane. In the end, the processing technology of ultrasonic combined micro-machining micro-pits on working surface between friction pairs is analyzed and summarized. Furthermore, problems, shortage and its improvement means are also suggested. Then further study work is put forward. |
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