Research On Sheet Upsetting And Its Application In Composite Process Of Sheet Flattening And Fine Blanking

Sheet metal flattening is a comprehensive process of volume forming and sheet forming,on the one hand with the three-dimensional characteristics of the thickness difference,on the other hand the role of the object is thinner sheet.The process has the characteristics of saving material and strengthening the workpiece.In the process of sheet metal crushing,according to the size and deformation of the parts,the punch will be applied to a very high pressure,may lead to overload,resulting in mold cracking or fatigue cracks.Due to the large error of the existing flattening empirical formula,in order to obtain the accurate formula of flattening force for the sheet metal upsetting,in order to design the mold and select the hydraulic Press,the following research is carried out.Firstly,according to the geometric characteristics of parts and molds,the classification and characteristics of the sheet flattening are analyzed.At the same time,the velocity field ?the stress field and the strain field are analyzed in the process of flattening the solid plate,the hollow plate,the outer ring local plate and the inner ring local plate by the finite element software deform,on the one hand,the regular characteristics of the flow of metal materials in the flattening process of the sheet metal are clarified,on the other hand,the stress and strain distribution and the spreading law of the material in the material are studied.Secondly,through the orthogonal experiment,setting the flatten force of round plate as the goal,the importance of the material,diameter and thickness of the material and the friction coefficient are analyzed,Then the control variable method is used to carry out a single analysis of each factor,the impact of various factors on the forming force of the law;Again,through the study of rod upsetting and the deformation resistance and friction of closed die forging,flattening empirical formula the proposed mathematical model of solid and hollow sheet flattening forming force are put forward combined with the characteristics of sheet flattening,through the simulation of backstepping to get the key coefficient m;method for inner ring and outer ring local flattening force by adding shear stress and pier pressure,combined with engineering testing the result was validated.Finally,the flow stress curve of 20 steel was fitted by MATLAB,and the maximum flattening amount was calculated.In order to solve the problem of large crushing force,it is necessary to adopt the appropriate shunt decompression method according to the geometriccharacteristics of the parts,and analyze and compare the shunt decompression.Analysis of the application of the magnetic disk in the process of fine blanking and flattening composite process.In this paper,through the analysis of the flattening mechanism of the plate sheet,the finite element simulation results,the influence factors of the forming force and the mathematical model,the physical experiments are carried out to verify the process.The above research results are of some scientific research value and engineering significance,and provide some technical guidance for the flattening of the sheet metal in the fine blanking-flattening compound forming.