Process of back pressure deep drawing with solid granule medium on sheet metal

The experimental die apparatus of the solid granules medium forming on sheet metal was designed and manufactured. Typical parts, such as conical, parabolic, cylindrical and square-box-shaped components, were successfully trial-produced as well. According to the analysis of the changing trends of the cross-section shape and the wall thickness during the process, it can be found that the shape of the free deformation zone of the sheet metal, which is the most critical thinning area, can be described as an approximately spherical cap. According to this forming feature, back pressure deep drawing technology with solid granules medium on sheet metal was proposed to restrain drastic thinning at the bottom of the part through the joint friction effect of solid granules medium, the back pressure tringle and the sheet metal. Therefore, the deep drawing limit of the sheet metal is significantly improved. In order to fabricate thin-walled rotary parts with great drawing ratio and complex cross-sections, a finite element model based on the material property test of the solid granules medium was established to optimize the scheme of the back pressure deep drawing. The effects on the forming performance of sheet metal from back pressure load and the approach of blank holding control were analyzed through this model.