超声磨料对TC4钛合金电火花加工表面质量的影响

为改善TC4钛合金电火花加工表面质量,减少表面微裂纹、重熔层等表面缺陷,提出了基于电极振动的超声磨料电火花复合加工方法。在煤油工作液中混入12g/L的SiC磨料粉,进行了有无超声磨料作用的窄脉冲(脉宽小于1μs)电火花加工的表面粗糙度对比实验研究。实验结果表明:SiC磨料的超声振动作用使零件表面粗糙度Ra由0.5μm降到0.2μm左右;重熔层厚度、表面裂纹的扫描电子显微镜(SEM)照片显示,超声磨料作用使重熔层厚度减薄20～30μm,表面微裂纹得到有效控制;机理分析认为工作液高频振动及磨料对工件的冲击作用,是改善TC4钛合金电火花加工表面质量的主要原因。研究表明磨料的超声振动作用可显著改善TC4钛合金电火花加工的表面质量。

Effect of Abrasive Particle Ultrasonic Vibration on Surface Quality of Titanium Alloy TC4 in EDM

In order to improve the surface quality of titanium alloy TC4 processed by electric discharge machining (EDM), this article presents a new combined machining method of ultrasonic vibration assisted EDM by mixing the kerosene fluid with 12 g/L SiC abrasive particles. By comparing the surface roughness between EDM and the abrasive particle ultrasonic vibration assisted EDM in short pulses (with pulse width less than 1 μs), it is found that the ultrasonic vibration of SiC particles can improve the surface roughness R_a from 0.5 μm to 0.2 μm. The recast layer and surface cracks are analyzed by a scanning electron microscope (SEM). Results show that the thickness of recast layer is reduced by 20-30 μm and surface cracks decreased obviously with the action of abrasive particle ultrasonic vibration. Theoretical analysis indicates that the high frequency vibration of the fluid and the abrasive impulse forces of the abrasive particles on the workpieces are the major factors for improving their surface quality. It demonstrates that the combined action of ultrasonic vibration and abrasive particles can considerably improve the surface quality of titanium alloy TC4 in EDM.