ANALYSIS OF DIE DESIGN FOR THE STAMPING OF A BATHTUB

The die design for the stamping of the base of an enameled bathtub was performed using the three-dimensional finite-element method. The diff iculty encountered in the stamping process is the occurrence of both f racture and wrinkling. To facilitate the analysis, a series of experim ents was conducted to obtain the material properties and the forming-l imit diagram for the enamel steel used for the actual production and f or the finite-element simulations, the latter being first performed to analyze the metal-flow causing the wrinkles on the draw-wall. The str ain distributions obtained from the finite-element simulations were al so used in conjunction with the forming-limit diagram ro predict the o nset of fracture. In addition, the effects of blank-holder pressure an d friction on the occurrence of fracture and wrinkling were investigat ed. An optimum drawbead distribution on the die face was then determin ed, according to the finite-element analysis, to avoid the formation o f both fracture and wrinkles. (C) 1997 Elsevier Science S.A.