Deformation characteristics and fracture failure of multi-bosses forming process by plate forging

Local functional features in stamped components have been studied in detail due to unique advantages in saving individual parts, reducing maintenance costs, and realizing weight reduction. The present investigation focuses on the plastic forming process of the structure of multi-bosses including non-central symmetrical bosses and tri-bosses, typical local functional features. The technical route draws from a previous study on a central boss by the compression-drawing method and the extension to multi-bosses is built on a hybrid experimental–numerical approach with A1050 aluminum sheet. The results show that for the structure of non-central symmetrical bosses, radial location I of the boss structure is confirmed as a significant factor in boss forming, influencing not only the height but also the cross-section of the boss structure, and the value of I being 8 mm is proven to be the optimum solution for the given boss structure. Under the same deformation conditions, the degree of plastic deformation in the forming process of the tri-bosses structure is much higher than that in non-central symmetrical bosses due to the new cavity of the central boss and the height of the non-central boss in the tri-bosses structure is lower than that in non-central symmetrical bosses as a result of the absorption of the central boss. Moreover, fracture failure around the punch radius will occur when the maximum value of radial tensile stress exceeds the sheet tensile strength.