Multi-Physical Coupling Simulation And Experimental Study Of Magnetic Field-Assisted Micro-Electrochemical Machining

At present,difficult-to-cut metal materials in heat dissipation holes,microgears,microgrids and other tiny parts have been more and more widely used,micromechanical cutting has machining difficulties,low efficiency,tool wear and residual stress and other problems,electrochemical micromachining technology with its unique non-contact processing advantages are increasingly used in a variety of difficult-to-cut metal micro parts of the machining and manufacturing,and has cathode no loss,no cutting force,good surface quality,high efficiency and other significant advantages.However,due to the shortcomings of electrochemical micromachining,such as stray corrosion and difficulty in improving precision,it is difficult to get a wide range of practical applications.Previous studies have found that the introduction of magnetic field into electrochemical micromachining can well inhibit stray corrosion on the surface of the anode,thereby effectively improving the locality and machining precision of electrochemical micromachining.Since magnetic field-assisted electrochemical micromachining is affected by multiple physical fields such as magnetic field,electric field,flow field,temperature field,etc.,and the coupling relationship between various physical fields and the improvement mechanism of magnetic field on the precision of electrochemical micromachining have not been systematically revealed,it is of great significance to analyze the multi-physics coupling in magnetic field-assisted electrochemical micromachining.This paper mainly studies the coupling relationship between various physics,the influence of each physics on the precision of electrochemical micromachining,single physics simulation and multiphysics coupling simulation,etc.,and the main research work is as follows:(1)In order to obtain the influence of various physics on the precision of electrochemical micromachining in magnetic field-assisted electrochemical micromachining.The magnetic field,electric field,flow field,temperature field,etc.in the inter-electrode gap were studied,and the coupling relationships that play a major role in the boundary coupling,domain coupling,bidirectional coupling,single term coupling,direct coupling,indirect coupling,differential coupling,algebraic coupling,source coupling,flow coupling,attribute coupling,geometric coupling,etc.between various physical fields were discussed in depth.The enthalpy change and entropy change of electrochemical reactions generated in magnetic field-assisted electrochemical micromachining were analyzed,and it was found that the main sources of heat generation were electrochemical heat and Joule heating.The classical electromagnetic theory and the theory of electrochemical micromachining are combined,and the influence law of magnetic field on charged particles is introduced into the electrolyte to explore the driving mechanism of magnetic field on fluid.It is obtained that the magnetic field mainly changes the motion trajectory of charged particles through unidirectional domain coupling,drives the flow of electrolyte,and changes the conductivity of the electrolyte,so as to improve the machining precision.(2)With the COMSOL software for transient simulation analysis of single physics field,the morphology of electrochemical micromachining micropits under processing voltage,electrolyte flow rate,electrolyte temperature,magnetic field and other parameters was simulated,and the influence law and degree of influence of each physics on electrochemical micromachining were obtained.(3)In order to obtain the influence of magnetic field strength,voltage and electrolyte concentration on magnetic field-assisted electrochemical micromachining under the joint influence of various physical fields,the multi-physics coupling simulation analysis of magnetic field,electric field,flow field and temperature field was carried out.The simulation results show that the variation range of flow rate within the simulation parameters is 0.062～ 0.012(voltage4V～6V),0.074～ 0.086(magnetization strength 0.3T～0.7T),0.034～ 0.087(electrolyte concentration 5%～20%),so the influence of different parameters on the flow rate of the electrolyte is analyzed to obtain the degree of influence of different parameters on the flow rate of the electrolyte in the electric field> flow field > magnetic field.The temperature change range under multi-physics coupling is: 369°C ～ 406°C(voltage 4V～6V),350°C ～ 370°C(magnetization strength 0.3T～0.7T),350°C ～ 375°C(electrolyte concentration 5%～20%),so the influence of different parameters on the flow rate of electrolyte is electric field > flow field >magnetic field;The variation range of current density under multi-physics coupling is: 67.6 ～ 82(voltage 4V～6V),48.1 ～ 56.4(magnetization strength 0.3T～0.7T),12.3 ～ 48.1(electrolyte concentration 5%～20%).In summary,in order to improve the machining precision,under the premise of not affecting the normal progress of electrochemical machining,smaller voltage,larger magnetic field strength and smaller conductivity concentration should be selected as much as possible.(4)Comprehensive experimental verification was conducted based on the coupled multiphysics simulation.Based on the improved electrochemical micromachining machine tool,electrochemical micromachining experiments with different magnetic field strengths,different electric field intensities and different electrolyte concentrations were carried out,and the anode morphology and surface quality of micropits under different parameters were obtained.Then,the topography curve of multi-physics coupling simulation is compared with the topography curve obtained by actual processing,and the topography contour of actual processing is consistent with the topography profile result obtained by multi-physics coupling simulation,and the average error does not exceed 10%.Theoretical analysis,single field simulation,multi physical field coupling simulation,and experimental verification were conducted on magnetic field assisted micro electrochemical machining.It was proved that magnetic field can effectively improve the machining accuracy of micro electrochemical machining,with a 14.7% increase in machining accuracy.The feasibility of using multiple physical fields such as electric field,magnetic field,flow field,and temperature field coupling for magnetic field assisted micro electrochemical machining simulation analysis was also demonstrated.This study provides theoretical and experimental guidance for improving stray corrosion and improving the precision of electrochemical micromachining,and promotes the popularization and application of electrochemical micromachining in difficult-to-machine micrometal materials.