Stamping Process Analysis Based On The Cae Theory And Key Technologies

Sheet forming is a very important technology in manufacturing system, which is applied in automobile, aviation, electric, national defence industry and so on. The key point of die's design is making forming technics. Traditionally, it is greatly relayed on experience, that is why developing level of dies is limited and difficult to improve. With the development of FEM theories and computer simulation techniques which are applied in numerical simulation of sheet forming, CAE becomes a strong and useful tool for developing dies more and more.Nuclear theories about CAE were analyzed in the article, and based on three main defects of sheet forming, theories and methods of forming technics analysis based on CAE are approved, and applied in forming software CADEM which was developed by ourselves, the practicability of CAE software is improved greatly. The main innovative points are as follows:(1) Visible description of sheet's stability and predicting fracture are realized. Fracture is caused by sheet's tensile instability, Hill's totalized instability theories and Swift's diffuse instability theories which based on continuous mechanics are applied to isotropic blank; Marciniak and Kuczynski's theories are applied to orthotropic blank, which introduced thickness imperfections normal to the principal stress and strain direction as a groove pre-existing defects in the material. The stability of each part of blank at each moment is described by numerical method, and the results are shown by computer simulation, thus the fracture in sheet forming can be predicted preciously.(2) Visible description of sheet's stability and predicting wrinkle are realized. The energy theory and FEM are applied. Based on simple mechanical model, a concept of virtual bending stiffness and calculating method of critical stress of sheet's wrinkling are presented. To predict possibility of each part wrinkling, the critical stress of wrinkling is calculated beginning with zones of 16 elements, then searching or selecting zones to calculate, so as to find the easiest wrinkling zone which includes a element, and calculate the critical wrinkling stress of every element. By cloudfigures, wrinkling can be predicted obviously and preciously.(3) The optimum method of binder force based on CAE and Neural Net Method is provided in the analysis. In computer simulation, the sheet's stability in forming process is described each time. Some stability values of key spots (the easiest instable parts) are used as input parameters, and Neural Net Method is applied to optimize binder force. With the method, it is easy to obtain optimum binder force without special equipment to educate style.(4) The calculating method of springback is provided in the analysis. By CAE software, the factors infecting sheet's springback are analyzed by the numbers, and their effects are compared. The possibility of losing stability to the opposite direction in springback is pointed out, and formula of calculating critical stress is given and calculating method of springback considering Bauschinger effect is provided.The forming technics theories and methods are provided in the analysis. By the test of representative parts, they are applied in industry to solve technical problems. It is significant to improve quality, reduce the cost and cycle for dies developing.