| SiCp/Al composites have significant competitive advantages in terms of density,specific strength,specific stiffness,solderability,abrasiveness,and thermal properties.So it is widely used in the fields of aerospace,national defense,automotive,electronic instrument,etc.Because SiCp/Al composites are rich in high-hardness SiC ceramic particle reinforcements,when they are processed by traditional machining,the strong scoring of the tool surface by SiC particles makes the tool wear seriously,the processing cost is high,and the molding accuracy is poor.Compared with traditional machining,EDM has the advantages of no macro cutting force,wide application range,easy access to small material removal,etc.,and is not affected by the hardness and strength of the material.Therefore,EDM is an effective way to process SiCp/Al composites.During the process of EDM machining of SiCp/Al composites,due to the large amount of SiC-reinforced particles and the eroded matrix aluminum material staying in the discharge region,it is not conducive to stable discharge,affects the processing efficiency and accuracy,and restricts its wide application in related fields.Therefore,this paper develops ultrasonic composite processing technology based on EDM technology to solve the problems of low machining efficiency and machining precision in machining SiCp/Al composites by EDM hole machining.In this paper,the material removal mechanism of SiCp/Al composites during conventional EDM machining is theoretically analyzed.Based on this analysis,the influence of the additional ultrasonic vibration of the tool electrode on the discharge channel,discharge gaps,erosion discharges and processed surfaces in EDM was analyzed.Relying on the existing EDM machine of the research group,based on the piezoelectric effect theory and finite element method,combined with the WORKBENCH finite element simulation software,an ultrasonic vibration device system was designed and built The ultrasonic vibration system was tested for impedance and amplitude to achieve the axial stable ultrasonic vibration of the tool electrode.Based on the CFD theory,the theoretical analysis and simulation calculations of the machining gap flow field under the action of the tool electrode ultrasonic vibration were conducted.The effects of the tool electrode ultrasonic vibration on the change in the flow field velocity,pressure,and erosion particles discharge law were explored.The research results show that ultrasonic vibration of the tool electrode is conducive to accelerating the flow rate of the working fluid in the discharge gap,and promoting the discharge of erosion particles from the processing gap.The effect of peak current,reference voltage,pulse interval and pulse width on material removal rate(MRR),surface roughness(Ra)and width of overcut(WOC)of workpiece were investigated by single factor experiments was performed on the machining of SiCp/Al composite square holes on an EDM experiment platform with additional tool electrode ultrasonic vibration.The research results show that the workpiece MMR,Ra,and WOC increase as the peak current increases,the reference voltage and the pulse interval decrease;as the pulse width increases,the MMR increases at first and then decreases,while the Ra and the WOC gradually increase.Based on the single factor experiment,orthogonal experiments were performed on the EDM SiCp/Al composites forming holes,and the optimal combination of electrical parameters regimen for integrated a number of process indicators was obtained by the gray correlation method.The research results provide technical support for the practical engineering application of the EDM SiCp/Al composites forming holes. |
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