Optimization Of Hydro-mechanical Deep Drawing Of Cylindrical Cup Based On The Local Bifurcation Theory

In recent years, with the rapid development of automobile, aerospace and otherindustry, scholars of many countries have focused their research on the sheet metalforming process and its forming limit. Hydro-mechanical deep drawing (HDD) isespecially concerned, because this method needs less mould cost, can improve the forminglimit and reduce its forming pass. Due to the lacking of sufficient experience andexperimental data, currently the process design is still based on traditional try-and-errormethod, this resulted in high costs and long design period.With the progressive development of the computer and finite element technology,based on the finite element analysis (FEA) to simulate and optimize the process of sheetmetal forming has become a hot spot. But the criterion of the sheet metal forming embedin the software based on the FLD curve of the proportional loading experiment is notsuitable for non-proportional loading of hydro-mechanical deep drawing. Therefore, usingthe current FLD to predict the formability of deep drawing still has a big problem. And therolled sheet has certain anisotropy, which will make it more difficult to guarantee theaccuracy of FLD forecast results. Concerned with the above problems, this paper hascarried out the following works:(1) The development status of hydro-mechanical deep drawing at home and abroadwas presented. A variety of tensile instability theory was analyzed and the shortage of theexisting prediction criterion of forming limit was pointed out.(2)A simple introduction of the sheet metal anisotropy was made and thecharacteristic of planar anisotropy of rolled sheet was pointed out.(3) A variety of tensile instability theory was analyzed and a sheet metal forminglimit prediction method based on the bifurcation theory was proposed.(4) The prediction criterition has been programed using MATLAB in the article.Theprograme was linked to the finite element simulation results in order to predict theforming results.(5)The anisotropy coefficient of0.5mm thick stainless steel SUS436BA was determined, and the sheet metal tensile test was simulated. The article also used the localbifurcation theory as the criterion of forming limit for the prediction of crack tensilespecimen, and it was comformed that the prediction is in consistence with test result.(6) ABAQUS software is used to simulate and optimize the hydro-mechanical deepdrawing process, and the influence of various process parameters on the forming resultswas analyzed. The forming process parameters were optimized on the basis of forminglimit criterion of the local bifurcation theory, the reasonable forming liquid loading pathswas obtained.