Research On High-Efficient EDM Milling For Aerospace Difficult-to-Cut Materials

Difficult-to-cut materials such as superalloys,stainless steel,and aluminum-based composite materials are increasingly widely used in aerospace,military equipment,ships,weapons,and other fields due to their advantages of high strength,high hardness,corrosion resistance,and wear resistance.Following the requirements of low-cost and high-efficiency industrial production,this paper aims at the problems of low efficiency,high energy consumption and environmental pollution in traditional electrical discharge machining(EDM),and relies on the green and high-efficiency numerical control(CNC)pulsed by compounding electrical arc machining and electrical discharge machining milling to research the technology of high-efficient EDM milling aerospace difficult-to-cut materials,and achieved the following innovative research results:The flushing method has a greater impact on the machining performance of high-efficiency EDM.If the parameters such as the flushing pressure and the flushing speed are not ideal,it will cause problems such as low processing efficiency and large electrode wear.Based on the above,the effect of two flushing methods on material removal rate(MRR),relative electrode wear rate(REWR),and machining error(ME)are obtained.The surface micro characteristics of the recast layer,microhardness,discharge pits,micropores,micro-cracks,etc.of the processed materials are comparatively studied,and the law of the influence of the flushing method on the micro characteristics and the processing mechanism is revealed.Based on the gas-solid-liquid multiphase flow theory and discrete phase theory,a mathematical model for the movement of both working medium and machining debris in high-efficient EDM gaps is established.The pressure and velocity distribution in the machining gap under the two flushing modes are compared.The law of the position change of the machining debris with the flushing time is obtained,and the debris removal mechanism of high-efficient EDM milling is explained.The influence laws of gas type and gas content on the performance of high-efficiency EDM milling has been proved.Through the simulation,the behavior of the electric field and electric potential in the machining gap when the deionized water is mixed with air is clarified.By analyzing the recast layer,microhardness,element distribution,and other micro characteristics of the workpiece surface,the influence mechanism of gas on the high-efficient EDM milling performance is revealedOrthogonal experiments are designed to study the influence of current,pulse on-time,pulse off time,and rotation speed on the performance of high-efficient EDM milling.Based on the SPSS data analysis software,using the analysis of variance method,the single-objective parameter optimization was carried out,and the largest MRR,the smallest REWR,and ME are obtained.Based on the signal-to-noise ratio(S/N)of the original data,the grey relation analysis(GRA)is used to carry out the multi-objective optimization,and the optimal value of the comprehensive machining performance is obtained:MMR(2168.67 mm~3/min),REWR(-1.78%),ME(1.03 mm).