| 7075 Aluminum alloy is a cold-forged alloy with high strength,stress corrosion resistance and debris corrosion resistance,good stability,plasticity and anode reactivity.7075 Aluminum alloy plate is mainly used in high-speed rail,aerospace,automotive molds,mechanical equipment,tools and fixtures,especially in the manufacture of aircraft structures and other high-pressure structures that require high strength and strong corrosion resistance.At present,because of the soft material of cold forging aluminum alloy,the machining accuracy of microporous wall is difficult to be guaranteed.Therefore,in this paper,the preparation method of micro-abrasive tool and the polishing test of micro-porous wall surface are studied in depth for cold-forged 7075 aluminum alloy.Specifically including EDM,composite electroplating deposition,wire electrode discharge grinding,microelectrode milling,metal grinding and other methods.By analyzing the principle of honing and the design principle of honing head,SOLIDWORKS software is used to carry out three-dimensional modeling,designs the cutter shape,and ABAQUS software is used to carry out static and dynamic analysis,which proves the rationality and operability of the design of micro-abrasive tool.At the same time,the process route is designed and the base material of the one-word groove abrasive tool and the crossgroove abrasive tool is prepared,which lays a solid foundation for the next step of the microhole polishing by the micro-abrasive tool.In this study,a micro-cutting tool compound deposition device of nickel-diamond powder was designed.The device is equipped with a heating and stirring system.The nickel ring is used as the anode,and the cathode rotates along with the spindle and is connected with the SKD61 micro cutting tool.The parameters are used as the control factors to carry out a single factor quantitative study on the coating thickness and diamond adhesion,and the influence rules are summarized.The influences of spindle speed,current density,wetting agent content and diamond concentration on coating thickness and diamond adhesion were investigated by orthogonal experiment.Finally,the optimal parameters were obtained from the single factor experiment and orthogonal test table: the spindle speed was 50 rpm,the current density was12.5A/dm2,the content of wetting agent was 6% of the bath volume,and the diamond concentration was 50g/L.The mass ratio of nickel is 28.0%,and the adhesion ratio of diamond is 54.6%,which fully indicates that the diamond micro powder particles suspended in nickel solution can be deposited on the substrate of the micro abrasive tool successfully with the device,and the coating is uniform and the adhesion is good.In this paper,GA-BP algorithm is also used for nonlinear fitting and optimization of the interaction between parameters.Through input data,weights and thresholds are updated inside the system until they are close to the target value.Comparing the difference between the actual value and the predicted value,it is found that the prediction accuracy is higher within the error range.Then the objective function and boundary conditions were set to obtain the optimal parameters of diamond adhesion: spindle speed 50 rpm,current density 6.6A/dm2,wetting agent content 8.5% of bath volume,diamond concentration 15.8g/L.Finally,the micro-hole polishing experiment was carried out with a micro-abrasive tool and the effect of cutting parameters on the roundness and surface roughness of the micro-hole was studied.Comparing the advantages and disadvantages of one-groove grinding tool and cross-groove grinding tool on micro-hole polishing,it is concluded that onegroove grinding tool is more stable in cutting process. |
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