Deformation Behavior of Tool and Workpiece in Plate Compression

The influence of the combinations of the materials of plate and die on the deformation behavior during unloading in compression of a plate with a high ratio between the diameter and the thickness is investigated by simulations. A plate becomes thicker by elastic recovery during unloading in plate compression for a small ratio of thickness reduction in loading. On the other hand, a plate becomes thinner by the additional compression caused by the elastic recovery of die during unloading for a large ratio of thickness reduction in loading. The turning points by the ratio of thickness reduction from thicker to thinner during unloading depend on the combination of the materials of plate and die. The amount of thickness reduction during unloading is evaluated using the increase in plate diameter during unloading. Increase in plate diameter is large for the conditions that the friction hill in loading is large. Deformation behaviors of a plate using crown dies which are designed to obtain a uniform thickness plate are also investigated. The additional reduction of the thickness during unloading contributes the flatness of the plate.