A New Forming Method of Triple Cup by Plate Forging

A new forming technique to produce a cup with an upper and lower hollow boss by plate forging is proposed. In this process, the sheet metal is worked into a drawn cup by the deep drawing process and then deformed to the target shape by compressing the cup edge. One-stage edge compression process and two-stage compression process are discussed. The tool pressure and surface expansion ratio in the two-stage compression process are more favorable than those in the one-stage edge compression process. A series of two-stage compression experiments are carried out by using a steel sheet for deep-drawing. A product with 1.5 mm in boss thickness and 15 mm in boss height is formed successfully by the two-stage compression process and its shape coincides well with the FEM simulation.