Research On Micro-hole Machining By Ultrasound Vibration EDM

In the process of ultrasonic vibration EDM machining micro-holes,there is a bottleneck problem that the corrosion products stay in the gap flow field,which seriously restricts the processing depth-diameter ratio and aperture.In order to solve this problem,this paper studies the technology of micro-hole ultrasonic vibration EDM,and designs a set of ultrasonic vibration system and variable parameter spiral electrode combined with the characteristics of micro-hole machining.The specific work contents are as follows.Based on the research project,the fixture for locating and clamping the injector nozzle is designed to ensure that the injection hole can be machined without changing the EDM machine tool.The conical ladder ultrasonic horn is designed for the purpose of the design of the amplitude transformer and the amplification coefficient of the horn.The modal modes satisfying the processing requirements are analyzed by modal analysis and harmonic response analysis,and the reasonable amplitude amplification factor is determined.Based on theoretical analysis,the mathematical model and three-dimensional model of variable-parameter helical electrode are established.Through simulation experiments,the flow state of working fluid medium of cylindrical electrode and variable-parameter helical electrode is compared,including working fluid velocity and gap pressure.It is concluded that the variable-parameter helical electrode is more effective in discharging corrosion products in machining gap.Contrastive experiments of micro-hole EDM using cylindrical electrode and variable parameter spiral electrode were carried out respectively.The advantages of variable parameter spiral electrode compared with cylindrical electrode in micro-hole EDM were verified.After that,the experimental study on the model nozzle of ultrasonic EDM was carried out.Three nozzle holes with a ratio of 5:1 of depth to diameter were machined withvariable parameter spiral electrodes of 1mm in diameter with and without horn respectively.By comparing the processing efficiency of the two holes,it was found that in the case of horn,when the amplitude of ultrasonic vibration was large,the average processing time of the hole was longer than that of the unused horn.The time of the latter is 0.47 min shorter than that of EDM alone.The results show that the micro-hole EDM based on ultrasonic vibration and variable parameters spiral electrode can effectively improve the efficiency and quality of micro-hole machining,and improve the outstanding problem of the retention of corrosion products.It is of positive significance to improve the efficiency of micro-hole EDM based on ultrasonic vibration.