| With the rapid development of China’s industrialization,stainless steel has been widely used in the construction industry,light industry,railway and automobile industry,in which the application of the automobile is mainly concentrated in the car exhaust system.This paper first introduces the research status of stainless steel at home and abroad about characteristics and application in stamping,and summarizes the good forming performance of austenitic stainless steel,but the difficulty of stamping,including deformation hardening significantly,easy to crack and wrinkle and easy adhesion with the common mold material.Then the main contents and chapters of this paper are introduced.In this paper,the basic theory of finite element numerical simulation of sheet metal stamping is introduced,including the element type,the yield criterion of elastoplastic body and the related constitutive model,the treatment of contact and friction problem,and the finite element calculation method,Summed up a set of stamping numerical simulation theory suitable for the stainless steel.As the poor working environment of automobile exhaust system,accompanied by high temperature oxidation,high temperature fatigue,corrosion failure and other failure forms,so the stainless with good performance of stable and excellent corrosion resistance should be used.The double-layer stainless steel muffler shell with the thickness of 0.7mm and 0.5mm is taken as the research object,the idea of the numerical simulation analysis and optimization of the stamping is summarized,and the stamping process is planned.By analyzing the disadvantages of AUTOFORM analysis,this paper introduces the concrete steps of pre-processing in Hypermesh.Aiming at the optimization of the first drawing process of the muffler shell,a four factor and four level(L16(44))scheme based on the orthogonal test method is proposed.The four factors of the test are the shape and size of the blank,the blanking force,the drawbead and the friction coefficient between the two layers.The maximum thinning rate αup、αlow and the maximum thickening rate βup、βlow are test indicators to assess the risk of sheet cracking and wrinkling.Through the analysis and processing of the simulation data,it is shown that the influence of each factor on the maximum thickness reduction of the stamping parts is:the blank holder force>the blank shape>the drawing bar>the friction coefficient,and on the maximum thickness increase of the stamping parts is:blanking force>pull the tendons>blank shape>friction coefficient.The best combination of the parameters for the first forming is BL4,the blank holder force is 350KN,the drawbead is DB3,the friction coefficient of the double plate is 0.2,and the rationality and correctness of the method is verified by the product.Because the importance of blanking process on the quality of punching parts and mould life,coupled with the specificity of stainless steel relative to low-carbon steel.This paper focuses on the impact of the blanking gap on the punching section of the parts,and summarizes the selection of the mold gap and the solution of the blanking burr in the stamping process.In addition,several kinds of mold materials can be used for drawing stainless steel,which can provide some reference and reference for practical manufacturing. |
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