| Deep special-shaped hole is an important structural of deep hole parts.Because of its characteristics of high torque,good guidance and high motion stability,it is widely used in mining equipment,aerospace and other fields.The traditional machining of deep special-shaped hole parts has the weakness of low machining rate and large tool loss.However,electrolytic machining(ECM)has the advantages of no cathode loss and no contact stress,which has become an effective technical means to manufacture deep special-shaped hole parts.In this paper,the key technology research of ECM of deep special-shaped holes is studied.The main contents are as follows:In order to solve the problem of workpiece necking and hole wall flow ripple caused by uneven gap flow field of deep special-shaped hole.In this paper,the preliminary design of tool cathode's structure,flow field simulation and cathode optimization were studied based on the special-shaped hole with large aspect ratio.The structural feature of deep special-shaped hole parts was analyzed;the positive flow liquid supply was adopted,preliminary design and material selection of cathode parts of combined tool was carrying out.Three kinds of liquid filling structures were set up on the cathode arc working teeth,including liquid filling hole,liquid filling groove and liquid filling hole groove.Nine groups of flow field geometric models were established.The machining gap were 0.2mm,0.25mm and 0.3mm.The fluid filling structure was increased fluid hole,increased fluid groove and increased fluid hole groove.Based on COMSOL Multiphysics simulation software,RANS k-co turbulence model was used to analyze the variation of velocity and pressure of electrolyte flow field in machining gap by velocity cloud image method and uniformity index method.The simulation results show that when the machining gap was 0.3mm,the angle of the spray hole was 15°,and the structure was the combination of the liquid feeding hole and the 3° liquid feeding groove,the flow field uniformity index was 0.88,and the flow field stability was the best.The optimization design of cathode structure was realized through the simulation study of gap flow field.The ECM process test was complete by the cathode of 15° liquid spray hole and 3° liquid increasing hole slot.Fixture was designed and hydraulic parameters,working gap,current density,feeding rate and working voltage were selected.Manual and automatic control of voltage were used to solve the problems of workpiece closing and ripple.Through the measurement of the formed parts,the processed test pieces meet the dimensional design requirements.Aiming at the problems of similar structure,different size and long development cycle of cathode design for deep special-shaped hole parts,the demand analysis were carried out.UG 12.0 modeling software and C++programming language were used to realize the digital modeling of cathode of electrochemical machining tool for deep profiled hole parts.By establishing mathematical expression of cathode sketch and introducing digital modeling method of assembly relationship,the automatic modeling and assembly of the three dimensional modular combined cathode controlled by parameters such as large diameter,small diameter,slot width,current density and machining clearance were realized.Specific application of UG system in the design of ECM cathodes was explored,it satisfied the actual needs of the rapid design and modification of the cathode of the deep special-shaped hole electrochemical machining tool. |
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