Study On Electrochemical Forming Technology Of Array Variable Cross Section Microstructure

The complex and precise variable cross-section array pit structure is widely used in medical machinery,aerospace,automobile manufacturing and other key parts.At present,the machining technology of variable cross-section array pit mainly includes traditional precision micro milling,die stamping,micro EDM and ECM.However,how to process the variable cross-section array pit structure with high efficiency and precision on the surface of thin-walled workpiece has always been the difficulty in the manufacturing field.Aiming at the dimple structure of variable cross-section array on 17-4PH stainless steel,this paper presents an electrochemical machining method of radial mid spray liquid to form the dimple of variable cross-section array.Because this technology is a non-contact processing forming method,it has significant advantages over other processing technologies,including independent of material hardness and toughness,no heat affected layer,prevention of tool wear and low-cost high-efficiency production,suitable for stainless steel,titanium alloy,high-temperature alloy and other difficult to form metal materials.First,the electrochemical dissolution characteristics of the 17-4PH stainless steel of the workpiece material were studied using an electrochemical workstation.Through the analysis of the polarization curves of different types and concentrations of electrolytes,this paper finally selected Na NO3 with an electrolyte of 1.5mol / L Solution.Secondly,according to the structural characteristics of the target workpiece,two different liquid inlet cathode structures,side spray and radial medium spray,were designed.The COMSOL simulation software was used to model and simulate the flow fields of different liquid inlet methods.The experimental investigation of the flow field simulation found that the radial mid-spray injection improves the accuracy and forming consistency of the pit structure profile;and designs and manufactures special tooling fixtures for the cathodic structure model of the mid-spray injection.Furthermore,by comparing and analyzing the advantages and disadvantages of the replication accuracy and repetition accuracy of the array pit contour processed under two different mechanisms of pulse current and pulse voltage,the pulse current is finally determined as the experimental mechanism of this subject.Then,through the study and analysis of the influence of different process parameters(electrical parameters,working fluid parameters,motion parameters)on the shape,size and machining stability of the variable cross-sectional pit structure of the electrolytic forming array,the variable cross-sectional array of electrolytic forming is obtained Process parameters of pit optimization: 32 A pulse current with a frequency of 5KHz and a duty ratio of 50%,a pressure of 0.4Mpa,and a feed speed of 0.36 mm / min,which mastered the formation of array pits.Finally,for the target workpiece,a complete cathode structure was designed and manufactured,and the array recesses with length,width and depth profile dimensions of 1750 ± 20μm,1000 ± 20μm and 400 ± 10μm were successfully processed under optimized process parameters The pit completely meets the requirements of the target workpiece.At the same time,in the actual processing process,the average processing time of each piece is 2 minutes,which truly realizes the high-efficiency and highprecision processing of the variable cross-sectional array pit structure.