Research Of Techniques Of Curved Flanging

Flanging is an important forming process in sheet metal stamping industry, and is extensively applied in the field of automotive industry, aviation, astronavigation, household electrical appliances, etc. Since the need of assemblage and the shape of the product, curved flanging of sheet metal is required frequently. There are many defects of curved flanging parts in real product, such as wrinkle, fracture, spring back, etc. So, the research of the formability of curved flanging parts has important directive meaning to real product. Thanks to the continual development of the technology of computer and numerical simulation, more and more researchers take advantage of the technology of computer numerical simulation to study the process of sheet metal forming. The technology of computer numerical simulation can find the defects of current technology, mold structure, the dimensions of blank, etc. before real product, and corresponding effective method can be used. In this way, the cost of production can be reduced and the production cycle will be cut down. Unfortunately, simulation of flanging is a relatively difficult task, and the formability is not so clear so far. Aimed at this situation, in this paper, the formability of sheet metal curved flanging by three different techniques is analyzed making use of DYNAFORM, a sheet metal forming analysis software.There are many curved flanging parts which have similar watch and a few differences in only several key sizes or types. In order to simplify the research, in this paper, all the curved flanging parts are abstracted to a simple model. Some key dimensions that have been used to define a curved flanging part have been introduced, such as the length of straight sides L, the radius of the underside R, the height of the flange wall H, the width of the underside B and the radius of rounded angle r. The author has summarized the three different forming techniques of sheet metal curved flanging in common use, they are two-bend technology, flange after bend technology and one-off forming technology. The author has also introduced their forming process and mold configuration. Large numbers of simulations have been done to curved flanging parts of different dimensions and different techniques by software DYNAFORM. By the analysis to the result of the simulations, the effects of three key geometrical parameters , the length of straight sides L, the radius of the underside R and the height of the flange wall H, on the tangential strain of curved flanging parts have been summarized.The flaws of the curved flanging parts made by the three different techniques are listed by the analysis of the tangential strain pictures, FLD pictures and the thickness pictures in the post treatment of DYNAFORM. And the author has got the regular pattern between the formability of curved flanging parts with different dimensions and the three different flanging techniques. According to the regular pattern, the author has recommended different flanging technique to parts with different dimensions. And the result of the research will do much good to the real product.