Preliminary Study On Stamping Forming Of A Variable Cross-section Elbow Tile

A variable cross-section elbow tile used for a vehicle exhaust system has a special shape. it is difficult to use common stamping process to forming directly. The article collected approximately workpiece forming cases, reduce them to integral and non-integral forming ways.According to L-shape, the article camed up with three schemes, one-piece forming, S-shape two-piece forming, O-shape four-piece forming. First mould numerical model used for simulation was established, then software Dynaform was used to numerical simulation research, the merit and demerit of three schemes was compared:(1)One-piece forming, the mould is simple and reliable, but inside corner of the elbow would be crack for stress concentration.(2)Two-piece forming, the mould load balance. but the thru of semicircle section of elbow would be crack.(3)Four-piece forming, it is high efficiency, but the thru of semi-ellipse section would be wrinkle. For these problems, the improved methods of three schemes were used to avoid the defects, from four aspects blanking, mould structure, technological parameter and technological process.In the process of research, four feature size of variable cross-section elbow have effect on forming difficulty of elbow tile. Orthogonal experimentation was taken into the research. corner degree ?, radius of curvature R, depth of ellipse end H, breadth of ellipse end B, were turn as independent variables, three variables were set for each size factors. 9 orthogonal tests were taken research on one-step forming of elbow tile. The change rate of thickness ?, and the offset of inside material of semicircle section end ? were turn as a measure of forming difficulty. The primary and secondary order of four factors' incidence to ? was gotten through range analysis: ?>H>R>B, the order incidence to ?: ?>H>B>R. Conpositing four groups data, the primary and secondary order of four factors' incidence to forming difficulty was: ?>H>R>B.These three schemes to forming of variable cross-section were practicable, each has advantages and disadvantages. Four feature factors have effect on forming difficulty. So forming coefficient of variable cross-section elbow tile decided by multiple factors,it can not be gotten easily like drawing and turnup decided by two factors.