干式电火花接触式加工聚晶金刚石试验研究

Experimental research on dry-type EDM contact machining of polycrystalline diamond

基于过渡金属(钼)电极可提高聚晶金刚石(Polycrystalline Diamond,PCD)的加工效率,气中电火花加工可减少PCD加工石墨化问题的优点,提出了PCD的干式电火花接触式加工方法。在极间开路电压为36 V,钼丝为电极条件下,首先进行了在不同工作介质中加工金刚石平均粒径为5μm的PCD的对比试验,发现干式加工可以稳定持续地对PCD进行电火花加工,基于加工过程放电状态特点对其加工原理进行了分析。其次,进行了接触式和非接触式加工PCD的加工效率试验,得出结论,即外加载荷为20 g条件下的电火花接触式加工的加工效率比最大进给速度为5μm/s的电火花非接触式加工的加工效率要高,同时对加工效率提升的原因进行了分析。接着进行了干式电火花接触式加工效率对比试验,发现在一定条件下随着外加载荷的增加,加工效率降低,并通过放电状态曲线分析了加工效率降低的原因。最后,对PCD工件进行了拉曼光谱分析,进一步分析了加工效率随着砝码质量增加而降低的原因。

Based on the advantages that transition metal(molybdenum)electrode can improve the processing efficiency of Polycrystalline Diamond(PCD),and the Electrical Discharge Machining(EDM)in gas can reduce the problem of graphitization in PCD processing,a dry-type EDM contact machining method for PCD was proposed.Under the conditions of 36 V inter-electrode open circuit voltage and molybdenum wire as the electrode,the comparison machining experiments of PCD with 5μm average diamond particle diameter in different working media were firstly carried out,and it was found that dry-type EDM can stably and continuously process PCD.The machining principle was analyzed through the characteristics of the discharge state in the machining process.Secondly,the PCD machining efficiency experiments of contact and non-contact machining were carried out,and it was concluded that the machining efficiency of EDM contact machining under the conditions of 20 g external load was higher than that of EDM non-contact machining with the maximum step speed limit of 5μm/s,and the reasons were analyzed.Then,a comparison experiments on the efficiency of dry-type EDM contact machining were carried out,and it was concluded that under certain conditions,with the increase of the external load,the processing efficiency decreased,and the reason for the decrease of processing efficiency was analyzed through the discharge state curve.Finally,Raman spectroscopy was performed on the PCD workpiece,and the reason for the decrease of processing efficiency with the increase of the weight mass was further analyzed.