Research On Key Technology Of Electrochemical Machining Of Titanium Alloy Triangular Grid Holes

With the continuous progress of the aerospace industry,higher requirements are put forward for the processing technology of high-performance materials and complex structures.Titanium alloy grids have been successfully used in the structural design of stealth fighter inlets,launch vehicle tanks,and stealth aircraft.Therefore,it is extremely important to achieve high-precision and high-quality processing of this type of structure.Electrochemical machining is to realize the copy forming of the workpiece in the form of ions with the advantages of non-contact,no cutting force,no cathode loss,and high processing quality.More importantly,it shows significant advantages in the processing of titanium alloy grids.In this thesis,titanium triangular grid holes are chosen as the research objective,the development of titanium alloy TC4 electrolyte formula,cathode structure optimization design,multi-physics coupling simulation analysis of gaps,forming laws,and optimization of processing parameters are studied,the specific content is as follows:(1)The electrochemical workstation is used to measure the polarization characteristic curves of titanium alloy TC4 in different electrolytes to complete the preliminary selection of electrolyte formulations.Through electrolytic machining of round holes,and the exploration of the effects of different additives on the dissolution of titanium alloys are explored,finally through the electrolyte formula of 11%NaCl+5%NaN03+saturated EDTA is obtained.(2)In order to achieve the optimal design of the tool cathode structure,the preliminary design of the cathode is completed by the equal gap method.The layout of the 5 liquid channels is analyzed and compared through the gap flow field simulation,the layout form of the circular liquid channel with better flow field is obtained,and the size of the liquid channel is optimized.At the same time,the influence of inlet pressure and outlet pressure on the flow field state is analyzed.The electrical characteristics in the gap are obtained through the coupling simulation analysis of the gap multiphysics.(3)To study the forming law of the electrochemical machining of titanium triangular grid holes,a special tooling fixture is designed,and the forming theory of the electrochemical machining of titanium triangular grid holes is explored.The single-factor test scheme is adopted to analyze the influencing of processing voltage,duty cycle,inlet pressure,cathode feed speed affect the side clearance and surface roughness.(4)Through the design of orthogonal experiments with four factors and four levels,Taguchi algorithm and grey relational theory are used to optimize the process objectives,and the primary and secondary influences of different factors on the comprehensive optimization objective are obtained as follows:processing voltage>feed speed>duty cycle>inlet pressure,and obtain the optimal combination of processing parameters:processing voltage 20V,duty cycle 35%,inlet pressure 0.7MPa,feed speed 0.55mm/min.The optimized parameters are used to process qualified titanium triangular grid holes,its side clearance is 0.35mm,the size error is 0.14mm,and the surface roughness is 0.812?m.The theoretical and technological test analysis show that electrochemical machining is an effective method to achieve high-precision and high-quality processing of titanium triangular grid holes,and at the same time it provides an important technological reference for the processing of some difficult-to-machine materials and complex special-shaped holes.