Research On Stamping-forging Thickening Process Of A Round Sheet Metal In Center Areas

With the development of manufacturing industry in the world, using the traditional method of machining and welding to make the plate parts of uneven thickness can not meet the higher demand for industrial products. Sheet metal stamping-forging which combines the traditional forging and stamping process is an effective method to form such part. In this research, a new method was proposed to produce disk-like parts with thicker center area. In the method, the center area of the sheet was drawn into the die cavity, and then the bulging portion is compressed with the gripping of the flange. The technology is a near-net forming process which can manufacture products with high property and efficiency.The effects of forming parameters on the the maximum thickness Rt and the thickness fluctuation E of the thickened workpiece center area is investigated based on orthogonal test with FE simulation and experiment. The deformation rules of the piece shape and thickness are investigated to summarize the reason why different factors have different influence on the effect of thickening. An optimized parameters group was determined and verified to get a better thickening result.The results show that the punch radius R0, the radius R1 of round bottom, the punch stroke H as well as the clearances D between punch and die have great influence on thickening effect, but the die chamfering R2,R3 have no obvious impacts on thickening effect. Both the maximum thickness Rt and the thickness fluctuation E increase with the increase of H whereas decrease with the increase of R0 and D. Furthermore, the influence rank of the parameters and their interactions on the Rt is H>D>R0>H×D>R0×D>R1>R0×H, the influence rank of the parameters and their interactions on the E is H>R0>D. Other parameters or interactions have no strong effects.The data shows that Rt is proportional to the lateral wall angle of the drawing parts and the E is basically proportional to the largest reduction ratio of drawing process. The difference in parameters leads to the variation difference in sheet thickness, which cause the shape difference in the drawing parts especially in the lateral wall angle and the reduction ratio. In the end, two form of forming process including uniform center zone thickening and no-uniform annular zone thickening is determined. Uniform center zone thickening of 14% and no-uniform annular zone thickening of 50% in round sheet metal can be obtained by using the optimized parameters group.