| 摘要 |
A bag having side gussets and a simple but incomplete bottom seam weld is made first from a tube having side gussets. The side gussets are then spread and the bag is pulled open at its bottom, whereafter the pulled-open wall portions are backfolded and flattened to form the bag with a block bottom, which is then sealed. At least the side gusset portions of the tube section are fixed to each other adjacent to the seam by the incomplete bottom seam weld formed first. When the bottom portion has been pulled open and has then been flattened to form a block bottom, the bottom seam edge strips which protrude substantially at right angles from the plane of the rectangular bottom are introduced into an open welding clamp and the incomplete seam is closed completely by welding. |
