Experimental Study And Finite Elements Simulation On Small-hole For TC4Alloy Drilled By EDM At High-speed

With the development of avigation and navigation, the requirements of materials is higher and higher. TC4(Ti-6A1-4V) is widely applied in frontier for its excellent mechanical and thermal properties, high specific strength, stable performance at moderate temperature, outstanding corrosion resistance and so on. Hole applied in frontier is very normal, for example, the blade in aeroengine almost used titanium, there are thousands of holes on it. today, the requirements for machining precision become higher and higher, because of titanium’s hardness and high melting point, the application of traditional processing methods is difficult to achieve processing accuracy requirements. Electric discharge machine (EDM) is the technical that removal materials by discharge energy to achieve processing purposes, regardless of its hardness,during the process, because of non-contact,there won’t produce a macroscopic force. EDM is suitable for materials hard to cut.KIC is used as an experimental machine for production of high-speed hole machine in this paper, a series of experiments is take on TC4alloy sheet of2mm thick with o.5mm diameter holes. The four factors and four levels of orthogonal table is chose, select peak current、capacitance、pulse-on and pulse-off as the process parameters, and select the small-hole machining efficiency and taper as targets. Based on the experimental datum, summarizes the relation between the single process parameter and the single target, also the effect ratio between them. The result reveal that, the effect ratio of the parameters on targets followed by large and small is peak current、capacitance、pulse-on and pulse-off. Grey relational analysis is used to optimize multi-targets, namely, taper is as small as possible under a certain machining efficiency. The results show that capacitance takes a great impact on taper and machining time.With the help of the super depth of3D microscopy, the surface quality of holes on TC4alloy is observed, analyzes of the effect of electrical parameters on surface quality. The surface is full of small discharge caves. Experimental data show that under low peak current and short pulse-on will cause the cave to be shallow and small. Low peak current and short pulse-on should be adopt in order to get better surface quality.Under the base of the physical and mathematical model. Gaussian heat is considered to be loading heat source, take full consideration of the joint effect of Gaussian heat and heat convection, the material’s physical parameters is temperature change, processing phase change is solved by enthalpy. Simulate the EDM machine TC4by single discharge,the distribution temperature is get under different peak current and pulse-on, also obtains the relation between electrical parameters and size of discharge cave. Under the result of simulation, machining efficiency is calculated.At last, the result of confirmatory experiment show that, the error between experiment and simulation is below15%, the simulation model is valid and predict the machining efficiency.