Research On Shaped Tube Electrochemical Drilling Of Micro-hole

The Micro-hole whose diameter is less than lmm has been widely applied in aviation, spaceflight, shipbuilding, military and other areas. In multiple processing methods of micro-hole, the electrochemical machining occupies an important position. Electrochemical machining technology has the advantages of wide processing ranges, no tool loss, independence from hardness, high processing efficiency, good surface quality, etc. It has the ability of removing metal material in the form of ions. Owing to these characteristics, it has broad application prospect in the field of micro-hole machining. Therefore the study of micro-hole electrolytic machining technology has great significance for improving the machining quality and precision of micro-hole, In this paper, electrochemical machining round and square micro-hole by shaped tube were studied.The process parameters of shaped tube electrochemical drilling micro-hole were studied. The influence of process parameters on machining precision was analyzed. Experiment results indicate that reducing processing voltage and duty ratio, increasing the pulse frequency can improve the locality of electrochemical machining, which means the improvement of the machining precision of tiny holes. A set of optimal process parameters were elected by orthogonal experiments. The dimension of side gap of the micro-hole less than40μm with the optimal process parameters:U=7V,f=30kHz and D=0.3.Regularity of the flow velocity distribution in the bottom gap was analyzed by the establishment of the finite element model. The factors that affect the process stability were studied. Experiment results indicate that the electrolyte with excess pressure easily lead to bad process stability and increase of micro-hole roundness error. An appropriate increase of the electrochemical machining gap is conducive to a more stable process.The exit morphology of square micro-hole manufactured by shaped tube electrochemical drilling were studied. Based on the defect of square micro-hole exit, the finite element simulation of the flow field is carried out. The analysis indicates that the nonuniformity of the flow velocity causes the nonuniformity of the electrolytic reaction speed, which resultes in the defect of square micro-hole exit. The result of analysis is consistent with the experimental results. The experiment that improves morphology of square micro-hole exit by extending processing time and building pressure-tight structure was carried out. The result shows that the morphology of square micro-hole exit can be improved effectively by building pressure-tight structure and the process is stable.