Drawbead Mechanics Characters And Influences In Sheet Forming

Drawbead is an important measure taken to control the sheet forming. As the industry, especially the automobile industry, is developing rapidly, the products produced by drawing become more and more complex and are difficult to make. So drawbead has become a key point of drawing die design. At present, the research on drawbead effect on sheet drawing is not profound to meet the request in practices. There are not principles of drawbead design and adjustment which can be applied to practice producing. That is a problem that should be solved as soon as possible in stamping technology. In this paper, the deformation of sheet at shoulder of die is studied by using FEM numerical simulation. It is put forward that the deformation zone is divide into five subzones when sheet is pulled through shoulder. The deformation features and mechanical characters of all deformation zones have been analyzed. The contact state and ruler of contact pressure distributing is studied. The relationship between stroke and moment and tension is discussed. Based on a large number of simulations, the influence of shoulder radius, back tension, friction condition and metal performance on sheet deformation features and mechanical characters is summarized. And the paper gives the update Euler equation and approximate equation of shoulder restraining force. The principle of deformation features and mechanical characters is studied systematically by using FEM analysis when sheet is pulled through drawbead. The process of sheet pulled through drawbead is analyzed. Based on these analysises, the paper obtain the relation between deformation force and friction force, the characters of round corners restraining force, the feature of deformation, the characters of drawbead restraining force components etc. These provide the theoretic guidelines for drawbead design and adjustment in practices. In this paper, the relation between geometric parameters and mechanical characters is studied thorough using the method that combine a large number of simulations and experiments. The principle of drawbead design and adjusting approach is established. And the paper directly put forward the reasonable range of main geometric parameters of drawbead. Also, the principle of large head drawing process is analyzed. The required condition of head forming is built. And based on that, the principle of drawbead design that is used in head forming is suggested. The experiment result is in good accordance with simulation result in the paper. It is verified that using FEM simulation as a tool is a good way to find out the principle of sheet forming, base on a large number of calculations. It can compensate the insufficiency of experiments and other analysis methods.