Key Technology Of Precision Electrochemical Machining Of Leading And Trailing Edges Of Double-Flange Titanium Aluminum Blades

Titanium-aluminum intermetallic compound is an excellent lightweight and high-temperature resistant material which has been used in important parts such as blades.It is considered as an ideal structural material for replacing nickel-based superalloys in the field of aero-engines.However,the titanium aluminum material has low plasticity at room temperature and high hardness.In addition,the shape of the blade surface is complicated,the leading and trailing edges are sharp and twisted,and the precision is demanding.As a result,the manufacturing difficulty is very large.Electrochemical machining(ECM)has become one of the main manufacturing methods of titanium aluminum blades because its good surface integrity,no loss of cathode,high processing efficiency.In this paper,the typical double-flange titanium aluminum blade is taken as the research object and the precision ECM of its leading and trailing edge is focusing on.The main research contents are as follows:(1)A multi-directional auxiliary flow mode based on liquid seal is proposed.In the ECM of longbody blades with double-flange,the machining short-circuit often occurs due to the uneven flow field.The simulation results of the flow field show that a large amount of electrolyte divided from the gap at the flange plates,which seriously affects the processing zone flow field.In order to improve the flow field state,a multi-directional auxiliary flow mode based on liquid seal is proposed.Four auxiliary liquid inlet ports are designed near the flanges and the electrolyte dividing is suppressed by hydraulic sealing.The simulation of the flow field is carried out,and the results show that the stability and consistency of the flow field in the processing area are significantly improved.A processing test was carried out to produce test pieces with good contour accuracy and surface quality by the preferred pulse processing parameters.(2)Master the influence of processing parameters on the forming rules of the leading and trailing edge of the blade.According to the characteristics of the leading and trailing edge,the effects of different cathode width,machining voltage,feed rate and duty ratio on the equilibrium shape of the ECM are investigated by electric field simulation.The curvature uniformity coefficient is used as the evaluation index.The arc-shaped trailing edge and the elliptical arc-shaped leading edge processing parameters is selected for a processing test.The test specimens have high contour accuracy and repeatability,which verifies the effectiveness of the parameter optimization method.(3)The experimental study on precision ECM of the leading and trailing edges of the doubleflange blades was carried out.According to the structural characteristics of the leading and trailing edges of the double-flange titanium-aluminum blade,the optimal feed direction of ECM was optimized and the fixture was designed.The titanium and aluminum metal test pieces were successfully processed by using the combination of the preferred ECM parameters,and the leading and trailing edge profiles of the test piece have high contour accuracy.The leading edge repeatability is 0.033 mm and the trailing edge repeatability is 0.036 mm.