| dc.description.abstract | This research is using ultrasonic-assisted electric discharge machining mold steel SKD61, and add silicon carbide powder whose resistance value is much lower than most of the electric discharge liquid to develop innovative electric discharge machining methods to replace the precision machining molding technology and improve the after-discharge machining,the surface roughness and the stability of processing, various electrical discharge machining parameters under study, such as: discharge liquid concentration, incident current, discharge cycle, ultrasonic power, etc., which affect the various processing characteristics of processing mold steel SKD61.The processing characteristics include the surface Roughness and processing time. And use the laser conjugate focal length surface topography measuring instrument (LSCM) and scanning electron microscope (SEM) to observe the surface microstructure and the processing area metamorphic layer.
The experimental results show that the addition of ultrasonic assistance during electrical discharge machining can effectively circulate the dielectric fluid. Also, the processing heat and electrical discharge slag can accelerate to leave the processing area, which can improve processing efficiency and shorten processing time.In addition, adding silicon carbide powder to the dielectric fluid can increase the conductivity of the dielectric fluid due to the proper concentration of silicon carbide solution, making the bridging effect more significant and improving the processing quality.In this study, single-factor experiments were performed sequentially, the result show that when the parameters are the concentration of discharge fluid 5×10-3 wt.%, peak current 0.8A, discharge cycle time 300µs, and ultrasonic power 4 segments, the best surface roughness 0.684 µmRa can be obtained. Compared with the surface roughness of 1.300 µmRa of the deionized water dielectric fluid without silicon carbide, the surface roughness Ra value after processing is reduced by 47%, accompanied by shorter processing time and a thinner recasting layer. | en_US |