大深径比微小深孔超声电火花加工工艺研究

Research on an ultrasonic vibration assisted electrical discharge machining technology of micro deep hole with high aspect ratio

针对难加工材料的大深径比微小深孔加工这一工艺难题,设计并制造了基于工件振动的超声电火花复合加工装置。该装置包括一个已优化的压电振子和一台普通电火花机床。为提高加工效率,对压电振子进行了优化分析,使压电振子具有合适的纵振模态、固有频率和较大的振幅,压电振子中陶瓷片具有合理地安装位置。选择模具钢作为加工材料进行大深径比微小深孔的加工实验,比较研究了超声电火花复合加工装置和普通电火花机床加工大深径比微小深孔的加工效率。实验表明,超声电火花复合加工装置的加工效率更高。研究了超声激励电压、脉冲电流、脉冲宽度以及脉冲间隙等参数对大深径比微小深孔加工效率的影响,得出各参数较优的设置值。根据实验结果可以看出,超声电火花复合加工装置可以有效地加工出直径为0.5mm、深径比为60的微小深孔,适用于难加工材料的大深径比微小深孔加工。

For solving the problem of machining micro deep holes with high aspect ratio in hard materials, an Ultrasonic Vibration Assisted Electrical Discharge Machining （ UV-EDM ） technology with workpieee vibration system was designed and manufac- tured. The device was composed of an EDM machine and an optimized piezoelectric vibrator. For advancing the machining effi- ciency ,the piezoelectric vibrator was optimized to have appropriate longitudinal mode and natural frequency, the appropriate placement of the piezoelectric vibrator＇ s ceramics, and the magnified displacement amplitude of the piezoelectric vibrator. The die steel was selected as experimental material. The machining efficiency of the UV-EDM and traditional EDM was studied contras- tively and it was found that the UV-EDM was more effectively than EDM in drilling micro holes. The parameters including ultra- sonic drive voltage, discharge current, pulse on-time and pulse off-time on the machining efficiency were studied and the optimum parameters were gained. The test result indicated the micro deep hole with diametert/~0.5mm and high aspect ratio 60 could be drilled effectively. The proposed UV-EDM is valuable in machining micro deep holes with high aspect ratio in hard materials.