| 摘要 |
The present invention provides a method of manufacturing a shutter to be slidably put on a protective envelope for containing a flexible disk. The method comprises cambering a flat metal strip, punching-out a blank having a shape corresponding to the development of the shutter from the cambered metal strip, and folding the blank along folding lines perpendicular to the cambered edges of the blank in a substantially U-shape. The shutter thus manufactured has opposite side walls cambered away from each other, and an end wall connecting the opposite side walls. The cambered opposite side walls of the shutter will neither diverge nor converge and the distance between the edges of the opposite side walls in sliding contact with the outer surfaces of the side walls of the protective envelope is maintained constant, so that the edges of the opposite side walls of the shutter in sliding contact with the outer surfaces of the side walls of the protective envelope do not rise from the outer surfaces of the side walls of the protective envelope.
|
