Study on the deformation of die and product in closed die upsetting

The experimental study has been performed to find the relation of the deformation between a die and a product in closed die upsetting. The strain of the die was determined by the simple experiment using the strain gauges attached to the outer surface of the die. The history of the deformations of the die and the product was also determined by the experiment and Lame’s formula. The internal pressure on the die causes the deformation of the die that affects the accuracy of dimension and shape of the product. The product with accurate dimension and shape can be obtained by analyzing elastic deformation of the die during closed die upsetting. The deformation of the die during metal forming process has been generally predicted by the experience of industrial engineers or by the finite element analysis. However, it is difficult to predict the dimension of the product at unloading and ejected states. In the present study, useful results for the deformation history of the die and the product were obtained through the experiment and Lame’s formula in closed die upsetting, which can be applied to the die design for the product with accurate dimension.