The numerical analysis and technique development on light truck muffler bracket forming

The light truck muffler bracket is a kind of deep and complicated stamping part which has curve flange. It is formed by once drawing with 3 mm thick 08TIL sheet. Since it is difficult to design good technique for the workpiece, after the muffler bracket was put into production, problems such as cracks at the bottom projecting corner and wrinkles at the curved flange corner often occurred. This led to high waste product ratio of 15 (and high substandard product ratio of 30). Therefore the part quality was heavily influenced, the production cost kept at high state for long term. In this paper, the geometry model of forming process part is built with the software Euclid3, the forming process of muffler bracket is numerically analyzed with the software LS-DYNA3D. The metal flow law and deformation character under the curve blankholding surface is revealed, in the meantime, the main reason of cracks and wrinkles appearing in the part during the forming process is studied, the direct reason of cracks at the projecting corner of muffler bracket bottom is verified as the metal flow resistance is too large at the preformed flange corner. The new technique that the preformation is finished by punch and die, the formation is finished by punch, die and binder have been developed. The waste product ratio and substandard product ratio have been descended below 0.05. Thus the quality problem which has puzzled production for a long time is successfully solved by using numerical simulation technology, theory bases are offered for the designing of stamping and die of similar workpieces.