脉冲电流大厚度电解线切割加工试验

航空航天难加工材料直纹面构件的高精度高表面完整性加工已经成为制造领域普遍关注和亟需解决的难题，电解线切割加工在高表面完整性要求加工场合上具有原理性优势。建立脉冲电流电解线切割加工模型，分析了工件厚度变化带来的影响。试验结果表明：随着工件厚度增加，电解液电阻减小，工件两端极间电压减小，加工缝宽变窄；双电层时间常数增大，脉宽时间内充电所能达到的电位降低，有效加工时间变短，平均电流密度较低；脉冲频率大于20 kHz时，最大进给速度随频率增加而快速减小，低于20 kHz时，最大加工速度差别较小。最后，采用脉冲频率20 kHz，以进给速度4 μm/s稳定加工出20 mm厚榫头/榫槽结构，表面粗糙度约为0.449 4 μm，表面质量、加工效率明显高于100 kHz加工效果。

Experimental research on pulse current wire electrochemical machining of thick structures

Precision and high surface integrity machining of thick rule structures in aerospace difficult-to-cut materials has become a common concern and an urgent problem in the manufacturing field. Pulse Wire ElectroChemical Machining (PWECM) has principal advantages in applications requiring high surface integrity. This paper discusses the effects of workpiece thickness on PWECM using the circuit model. Experimental results show that the electrolyte resistance, the inter-electrode voltage, and machined slit width were reduced with the increase of workpiece thickness. While the time constant of electric double layer in PWECM increases, the charging voltage including the effective machining time decreases. When the pulse frequency is greater than 20 kHz, the maximum electrode feedrate rapidly decreases with the increase of the frequency. When the pulse frequency is lower than 20 kHz, the difference of the maximum machining rate becomes smaller. Finally, a fir-tree-like turbine-disk tenon/mortise structure of 20 mm in thickness is successfully fabricated at the pulse frequency of 20 kHz and the electrode feed rate of 4 μm/s, and the surface roughness Ra was about 0.449 4 μm. The surface quality and machining efficiency at 20 kHz is significantly superior to that at 100 kHz.