Deep drawing is a process to create a three-dimensional cup from a flat sheet, and is a difficult process among press forming processes. A unique die was used to form the clad cup, to create a corrugated cup with gaps like the cross section of a corrugated cardboard. To reproduce the corrugated structure, the special die was used in which grooves were machined in the die shoulder and hard balls were densely placed in the grooves. The corrugated cup was produced using the composite die that combined this special die with a normal die. The blank material was an extremely thin pure titanium sheet and an extremely low carbon steel sheet. The sheet was 0.3 mm thick and circular with a diameter of 80 to 90 mm. The lubricant was a molybdenum disulfide-based machining oil. The punch diameter was 39 mm. The sheet thickness distribution, residual stress distribution, compression strength, and impact strength were evaluated. There was no destruction of the cup, and it had excellent formability. An ultra-lightweight and functional cup was obtained.
HARADA et al. (Wed,) studied this question.