| 摘要 |
In order to form a marginal rib on the side of a cylindrical wall (17), an extension (10b) that can be folded according to the dimensions of the rib is provided on the end of the wall (17). The extension is attached by means of a thin, deformable articulated tongue formed in the thickness of the wall by a groove in the side of the wall opposite to that receiving the rib. The extension is folded at 180 DEG against the side of the wall so as to form the rib (10b) when the tongue is folded onto itself. |
