Applied Basic Research On The Precise And Efficient Electrical Discharge Machining Of Titanium Alloy Grille

With the rapid development of aerospace field, the requirement of light-duty has become more and more strict. To achieve such a request, measures must be done from the two aspects of material and structure. Titanium alloy grille appears to be a promising structure in aerospace field as it combines the advantages of titanium alloy material, i.e. high strength-weight ratio and high heat strength, and grid structure, i.e. high strength-weight ratio and high self-stabilization. As a result, it has a great application prospect in the field of aerospace. However, the cutting performance of titanium alloy is poor and the cost is high. At the same time, the grid structure is also hard to machine as its low stiffness and high requirements for angular size. Therefore, The processing technology is a key factor restricting the further popularization and application of titanium alloy grille. EDM(electrical discharge machining) is one kind of ideal processing technologies of titanium alloy grille, which is not limited by the strength and hardness of metal material, has no macroscopical cutting force and could satisfy the high requirement of angular size. However, compared with other metal materials, the stability of titanium alloy EDM is poor, especially large depth of the grille hole, which makes the machining chips difficult to be eliminated and arc discharge more easily to happen, leading to low machining efficiency, high electrode wear and poor surface quality.It’s a problem urgently to be solved to improve machining efficiency and reduce electrode wear without sacrificing surface quality. Through the mechanism analysis and experiments research, the fundamental process rules of titanium alloy EDM are mastered, process parameters combination is optimized gradually and the optimal process parameters combination is determined for engineering application test. Main content is as follows:Firstly, in order to grasp the influence of different process parameters to performance characteristics, the process experiments of the electrode materials, graphite particle diameter, polarity, no-load voltage, servo SV, peak current, pulse duration, duty factor are conducted. Combined of titanium alloy EDM mechanism, the experiment results are analized and the optimal parameters under the certain condition are obtained.Then, to comprehensively evaluate the performance characteristics, adjustable process parameters are studied in experiments. Optimized process parameters combination is achieved based on gray relation analysis which converts multiple performance objectives into a single index(gray relation grade). Based on the confirmation experiment, the parameters combination can simultaneously achieve a higher material removal rate, lower electrode wear ratio and meet the requirement of surface roughness. With the increase of the machining depth, in order to effectively eliminate chips and improve the processing stability, the parameters combination associated with tool jump cycle is optimized. The results show that the different processing depth section has its own optimal parameters combination. The final optimal parameters combination effectively improves the overall processing stability and machining efficiency.Finally, the engineering application experiments of titanium alloy grille are conducted. Based on the previous experiments, the parameters combination is optimized for inclined plane machining, which effectively improves machining efficiency. The results show that the integral electrodes with different number of prisms exist different optimal process parameters combinations, and the machining efficiency is also different. The final sample meets the requirements of the machining efficiency and surface quality.Based on the research above, the database of titanium alloy EDM process parameters is set up and the optimized process parameters combination is obtained, which greatly improves the machining stability and efficiency of titanium alloy grille, and is of great significance to solve the difficult machining problem of titanium alloy grille widely used in engineering field.