Abstract: In the aero-engine, the machining accuracy and surface quality of the mortise/tenon structure used to connect the turbine disc and blade are extremely high. However, the existing machining technology cannot realize the low cost, high efficiency, and high quality machining of the turbine disc mortise. Electrochemical cutting has the characteristics of high machining accuracy, good surface quality and high machining flexibility, and the advantages of principle for low-cost machining of turbine disc mortise. To solve the problem of the uneven surface roughness of the sidewall cut by inner-jet electrochemical cutting using tube electrode, a method of inner-jet electrochemical cutting using tube electrode immersed in electrolyte was proposed. Under the combined action of a flow field that is relatively stable in the entire machining area and a flow field that flows rapidly in the machining gap, high efficiency and high quality machining of large thickness and difficult to machine materials is realized. The experimental results verified that the surface roughness of slit sidewall cut by inner-jet electrochemical cutting using tube electrode immersed in electrolyte is more uniform, and the overall machining quality is better compared with that of the inner-jet electrochemical cutting using tube electrode. The pressure of inner-jet electrolyte was optimized, and mortise structure of aero-engine turbine disc with surface roughness 1.247 μm was successfully fabricated on a 20 mm thick superalloy GH4169 at a feed rate of 4.5 μm/s and inner-jet electrolyte pressure of 2.0 MPa.

Key words: turbine disc mortise, electrochemical cutting, tube electrode, inner-jet, immersed in electrolyte