2019 年 60 巻 12 号 p. 2552-2557
In order to increase the number of applications of a copper cup, the formability of copper-resin-copper laminated sheets by the deep drawing process was investigated. Pure copper is a ductile metal with very high electrical conductivity, and its density is higher than that of aluminum and titanium. As part of the copper cup is made of resin, a reduction in the weight of the cup can be achieved. Furthermore, heat is more likely to be retained in the clad cup, and the resin clad structure provides protection for the contents from vibrations, like a vibration-damping composite steel plate. In the experiment conducted in this work, the materials employed were pure copper and resins, which were polycarbonate plastic (PC), nylon 66 (66N), polyvinyl chloride (PVC), and polyethylene terephthalate (PET). PC is commonly used due to its impact resistance. The initial thickness of the sheets varied from 0.2 to 0.5 mm and their blank diameter was 70 mm. The punch and the die, whose shoulder radius were 3 mm and 4 mm respectively, were made from cold tool steel JIS-SKD11 and the clearance between them was the same as the thickness of the laminated sheet. The deep drawing process was performed using an oil hydraulic press at a forming speed of approximately 10 mm/min. The laminated sheet was constituted by interposing the resin sheet between two stacked copper sheets. The laminated sheet was employed in the deep drawing process and a flat blank was formed into a circle by the punch. The multistage deep drawing process was, thereafter, employed to investigate the formability of the laminated sheet, which was successfully drawn without cracks. No failure conditions were identified at the bottom or side wall of the drawn cup. Many wrinkles, however, were observed on the opening of the cup, as no pressure was applied in this region by the blank holder during the deep drawing. The section of the drawn cup was observed to examine the formability of the resin sheet, which was within the desirable values. At the bottom corner of the clad cup, the reduction rate of the total thickness was lower than 6%.
This Paper was Originally Published in Japanese in J. Japan Inst. Copper 57 (2018) 142–147.
