Method of draw-forming a metal sheet having an organic film

摘要

A draw-forming method in which a disc-like metal sheet having an organic film or a cup made of a metal sheet having an organic film is held by an annular holder member and a drawing die, and a drawing punch and the drawing die are moved in mesh with each other and relative to each other, the drawing punch being so provided as to move into or cut of the holder member in concentric with the holder member and the drawing die, wherein at least either one of the annular holder member or the drawing die that had been pushing a residual flange portion is so moved as to discontinue the pushing just before the draw forming is finished in said drawing step, and the flange portion is drawn while liberating the rear end of the flange portion. This makes it possible to eliminate the defects inherent in the conventional draw-forming method or the draw/redraw-forming method, and to draw-form a metal sheet having an organic film into a flangeless cup without developing pinching, film hair or enamel hair at the upper portion of the cup, without causing the can barrel or the organic film to be broken during the drawing, and without permitting the tools that are used to be worn out or damaged, but maintaining excellent operation efficiency.