| Electrochemical machining technology is the main means of machining all kinds of difficult cutting materials,complex cavity and surface components.In the process of electrochemical machining,the workpiece does not contact with the tool,no stress generation;The workpiece is corroded by ion state,which can process any conductive metal materials.The processing speed is not limited by material hardness and processing area,and the processing efficiency can be guaranteed for the complex surface.Flow field,electric field,temperature field,electrode material solution characteristics and other factors will affect the electrochemical machining process,resulting in the workpiece surface quality and molding accuracy is difficult to ensure,which increases the difficulty of actual blade manufacturing.Therefore,based on the analysis results of electrochemical dissolution characteristics of electrode materials,it is necessary to conduct in-depth research on the multi-physical field corrosion model,process parameters and dynamic flow field model of complex blades,so as to reduce the test preparation period,optimize the flow field and improve the workpiece forming accuracy.The main research contents are as follows.1)Study on electrochemical dissolution characteristics of workpiece materials.The conductivity,open circuit voltage,polarization curve and electrochemical impedance spectrum of GH4169 in NaCl and NaNO3 classical solutions were studied,and NaNO3 was finally dissolved as the electrolyte.Secondly,the electrochemical impedance spectra of GH4169 at different concentrations and temperatures were studied,and the dynamic parameters of the electrochemical system were compared.From the point of view of electrochemical analysis,the theoretical basis for the selection of electrolyte types and parameters was provided.2)Multi-physical field corrosion simulation of complex blades.The multi-physical field coupling ecM model of complex blades under DC and pulse power supply was established by COMSOL software.The distributions of electric field,gas-liquid twophase flow field,temperature field and structure field in the machining process were obtained.The distributions of current density,bubble rate,temperature and removal amount under different machining parameters were analyzed.The results show that the bubble rate and temperature of the electrolyte increase with the flow,and reach a stable state in about 20s.Changing the feed rate has obvious influence on the bubble and temperature distribution in the gap.When the duty cycle of pulse power supply is reduced,the temperature and bubble rate in machining gap can be restored,but not to the initial state.Increasing the frequency of pulse power supply is beneficial to reduce bubble and temperature fluctuation and enhance the stability of electrochemical machining.3)Dynamic simulation of complex blade flow field.In Fluent,the internal flow field model of complex blade electrochemical machining in equilibrium state was built,and the dynamic characteristics of internal flow field in blade electrochemical machining were simulated by using the dynamic grid technology,which verified the rationality of flow field design and provided direction for fixture optimization.The results show that the model pressure tends to be stable within 15s,and the flow field in the gap can reach a stable state within 2s.There is a low-speed zone D at the rear end of the clearance,and the flow direction is disorderly,which may cause the phenomenon of lack of liquid,and diversion optimization is needed.Figure[75]Table[21]Ref[61]... |
PDF Full Text Request