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Research On Reducing Stray Corrosion Of Cascade In Electrochemical Trepanning

Posted on:2021-03-13Degree:MasterType:Thesis
Country:ChinaCandidate:J B LiFull Text:PDF
GTID:2481306479463574Subject:Master of Engineering
Abstract/Summary:PDF Full Text Request
A large number of integral components such as cascades are used in rocket engines to improve thrust-mass ratio and extend service life.Electrochemical machining has become an important manufacturing technology for integral components due to no material hardness limit,high machining efficiency and low cost.In this paper,research on reducing stray corrosion of integral cascade in electrochemical trepanning was studied:(1)An innovative electrochemical trepanning method in the presence of insulating particles was proposed,in which ceramic particles are used to form an insulating protective layer on the machined surface and thereby inhibit harmful stray currents.The dynamic electric field simulation results suggested that the presence of the insulating particles can dramatically reduce stray current and taper angle.The experiments research results showed that it reduced the taper angle from 4.03° to 2.00° at the feed rate of 1.0 mm/min,and the roughness decreased from Ra 1.32 to Ra 0.86 ?m for 650 particles with the diameter of 1.5 mm.(2)The flow field design and optimization research on electrochemical trepanning of cascade was carried out.The two electrolyte flow modes were designed,one flows from full contour of blade,another runs from the leading and trailing edges of blade.The flow field simulations and experiments suggested that flow mode of leading and trailing edges is more suitable for cascades.After it was optimized,the optimal structure parameters of insulating sleeve were obtained: vertical distance Y of6.0 mm,lateral distance X of 16 mm,outlet length L of 1.5 mm and height H of 13.5 mm.Optimization made its electrolyte flow homogeneously and surface quality improve significantly.(3)The machining parameters of TC4 titanium alloy cascades such as the electrolyte formula,pulse parameters and stray pitting protection scheme were optimized.The Na Cl solution was more suitable for TC4 titanium alloy electrochemical machining and picked as electrolyte.At the machining rate of 2.5 mm/min,the pulse parameters that the blade surface had no pitting and without broken shape were optimized to obtain: the machining voltage of 22 V,the duty cycle of 80% and the frequency of 1000 Hz.The process of stray pitting of machined blades was studied,the schemes of sacrifice,insulation double-layer and gas-assisted protection were put forward.(4)The application research on electrochemical trepanning of TC4 titanium alloy cascades was carried out.The segment of cascade without pitting corrosion was stably machined,and the machining time of single blade was 3.6 min and it can satisfy the machining quality request.
Keywords/Search Tags:electrochemical trepanning, integral cascade, machining taper, surface quality, flow field simulation
PDF Full Text Request
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