IMPROVEMENT OF DEEP DRAWABILITY OF METAL FOIL CUPS

Y. Marumo, H. Saiki, A. Onoue

Department of Mechanical Engineering and Materials Science, Kumamoto University, Kurokami, Kumamoto, Japan

Deep drawability of stainless-steel foil was investigated. In order to improve the deep drawability of the foils, foil-lap blanks in which thin sheets were lapped over the foils were used in the deep drawing operations. In the deep drawing, aluminum sheets, steel sheets and resin sheets were used as lap-sheets, i.e. the thin sheets for lapping. The deep drawbility was improved using aluminum lap-sheets and steel lap-sheets compared with that in the case of using a foil blank without lap-sheets. Cracks on the foil cups were prevented by the lap-sheet on the die side. Wrinkles on the foil cups were prevented by the lap-sheet on the blank holder side. When a foil cup was formed by sandwiching between polyethylene sheets, wrinkles occurred. However, wrinkles were prevented when an aluminum lap-sheet was on the blank holder side and a polyethylene lap-sheet was on the die side. The limiting drawing ratio increased compared with the limiting drawing ratio for the deep drawing of a foil blank without lap-sheets. The combination and types of lap-sheets determined the deep drawability of foil cups.

Keywords: deep drawing, foil, deep drawability, lap-sheets, wrinkles, fracture