| With the continuous development of modern industrial manufacturing technology,high aspect ratio small hole structure has been widely used in aerospace,military,mold,medical machines,automotive and other fields.ECM has the advantages of non-contact,not limited by material hardness,no tool loss,no remelting layer on the machined surface,no microcrack,no residual stress,etc.it is very suitable for deep small hole machining with high surface quality requirements.In this thesis,the technical difficulties of deep hole ECM are comprehensively analyzed,and the side wall insulation method of tube electrode composed of elastic quartz capillary and polyester resin transition coating is proposed.The research on deep hole ECM with super deep diameter ratio is carried out by using neutral sodium nitrate solution as electrolyte.Through process improvement,a through hole with a diameter of 1.1mm and a depth of 200 mm was machined on 304 stainless steel bar,and the depth diameter ratio reached 181.The main research work of this thesis is as follows:1)According to the technical requirements of deep hole ECM,a special ECM equipment is built;2)Many kinds of electrode side wall insulation preparation methods were used to test the durability.On this basis,the preparation method of composite electrode side wall insulation layer with elastic quartz capillary and polyester resin transition coating was proposed;4)Through orthogonal process test,the influence of different process parameters on ECM is studied,and the parameter combination with good machining stability is optimized;3)The experiment of inverted ECM is carried out,and the influence of inverted ECM on ECM stability is analyzed;5)In order to overcome the problems of poor machining stability caused by insufficient electrode stiffness of large aspect ratio tubes,an electrochemical machining process for small holes with self guiding electrode in the hole was proposed and verified by experiments under the optimized process parameters. |
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