Study On Powder-mixed Electrical Discharge Machining Of Titanium Alloys And Design Of Mixing Device For Dielectric Fluid

Electrical Discharge Machining (EDM) by transforming electrical energy into heat energy for the ablation of conductive material between repeated pulse discharge,can process arbitrarily complex shapes,regardless of the mechanical properties such as hardness,strength and toughness. EDM is an important processing means in the field of manufacturing technology. But there are some obvious defects in conventional EDM,such as poor surface quality and lower machining efficiency. Therefore these defects reduce the EDM applications.Powder-mixed Electrical Discharge Machining (PMEDM) by adding electric conductive fine powder such as silicon and aluminum into the dielectric fluid overcome those shortcomings to some extent,reducing the surface roughness,improving the surface quality,increasing material removal speed and processing stability. However PMEDM requires fine powder uniformly suspending in working fluid,there must be a special mixing equipment to complete the mixing operation.Firstly, this thesis reviews the research of EDM of titanium alloys. Based on the mechanism of EDM, this paper analyses the mechanism of powder-mixed EDM, and further analyses the effects of the fine powder on powder-mixed EDM.Then, this thesis designs the simple mixing device for powder-mixed EDM,and in the basis simulates the suspending uniformity of fine powders when mixing on the use of computational fluid dynamics (CFD) software FLUENT. Based on the simulation, structure optimization to the key parts of the device was made, and further installation and adjustment of the device were completed. Then the experiments of the sediment and suspending uniformity of fine powders were made.Finally, studies on the conventional and powder-mixed EDM of titanium alloys were made. Using the and uniform design, the experiments of conventional and powder-mixed EDM of titanium alloys were made, and based on the results of uniform experiments, fitting formulas were got for predicting the machining efficiency using the regression analysis. Powder-mixed EDM of titanium alloy increase the removal rate and improve the surface roughness.