Meso-scaled progressive forming of bulk cylindrical and flanged parts using sheet metal

摘要

In microforming, handling and transporting of meso/micro-sized intermediate preforms are difficult due to the influence of adhesive force on preform surfaces. In this research, the fabrication of meso-scaled bulk cylindrical and flanged parts by directly using sheet metal is investigated. The cylinder is made with a single stroke by shearing, while the flanged part is formed progressively via multi-stage shearing and extrusion. In forming of the flanged part, an intermediate preform is fabricated with sheet metal and a pre-pierced hole for positioning. The final part is blanked out from the sheet metal in the last operation. In such a way, the transporting, positioning and ejecting of the flanged part are facilitated. Furthermore, the characteristics of the developed meso-scaled forming process are extensively investigated. The shearing and fractured surfaces on both the cylindrical and flanged parts are found. The surface grains of the blanked cylinder have undergone severe deformation and been hardened, which increases the flow stress of the blanked cylinder. In addition, the longer cylinder and flanged part are obtained with fine-grained material. This implies that a larger amount of material flow to the lateral side of the workpiece in the case of coarse-grained material.