| 摘要 |
A method for fabricating a bag with a flat bottom comprises: making a flattened tubular element with lateral bellows; obtaining a quadrilateral bottom of a single piece, the perimeter of which has a size equal to that given by the sum of the tubular element and the bellows; folding the bottom in a single piece along one of its first axes, keeping the outer sides parallel to the axis and of a size equal to the initial one; folding the other two sides to identify two opposite bellows, bringing a central folding line of the bellows thus identified into a position perpendicular to the first axis; inserting the bottom thus folded into the flattened tubular element, bringing the two opposite bellows of the bottom so that they are astride of the lateral bellows of the flattened tubular element; and welding the ends facing outwards of the flattened tubular element and of the corresponding lateral bellows respectively to the outer sides, which are parallel to the axis and are of a size equal to the initial size of the bellows and to the inner edges of the two opposite bellows obtained in the bottom. The bag has a quadrilateral bottom added to the tubular element and welded around the perimeter. |
