| 摘要 |
A method and apparatus for manufacturing a square bottom bag is disclosed herein. The method comprises the steps of driving a web in a first direction and bending the web upon itself across its width as it is driven in the first direction to assume a U-shaped configuration, supporting the main panels of the web in the open U-shaped configuration and folding the side closure forming panels towards one another to an overlapping relationship and securing the side closure panels in the overlapping relationship to form side walls of a bag. The bag forming machine consists of a frame, a former mounted in the frame and a guide means for guiding an unwinding web around the former and drive means for driving the unwinding web around the former. Folding means is provided at opposite sides of the former for engaging the side wall forming portions of a web and folding them inwardly around the former to form closed side walls of a bag. Roll stock specifically designed for use in the method and apparatus is provided wherein a first pair and a second pair of bands of adhesive material of a type which is inactive to form a bond until placed in contact with an adhesive of the same type are applied to the inner and outer faces of the web adjacent said edges thereof. The bands of the first pair are laterally spaced with respect to the bands of the second pair so as to be out of alignment with one another in successive turns of the roll stock such that the successive turns are not adhesively secured to one another. An empty square bottom bag is provided which consists of a front wall, a back wall and a bottom wall formed from a unitary panel and including a band of adhesive on the outer face of said panel extending along the marginal edge portion of each side panel, the panels being folded inwardly so that the band of adhesive on one side panel is disposed at an interface with another side panel and therby secures the side wall panels with respect to one another in an overlapping relationship to close opposite sides of the bag and retain front, bottom and back walls in an open U-shaped configuration. |
