| 摘要 |
This invention is directed to a method for folding a tube into radially superimposed accordion pleats in which the tube is first placed in tubular form and clamped against radial and longitudinal movement at circumferentially spaced zones adjacent an open end of the tube. A first annular band of the tube is then forced radially outwardly and longitudinally to a position radially outwardly of the clamped zones, and is connected by a bight to the remainder of the tube, a part of which forms a second annular band lying radially outwardly from the first band. The two annular bands and the part of the tube containing the spaced zones are then clamped against radial and longitudinal movement, and a series of additional pairs of bands are then sequentially formed radially outwardly from the second band in the same way that said first and second bands are formed, with periodic clamping of all of said bands against radial and longitudinal movement occurring after each additional pair of bands is formed. This invention also covers an apparatus for placing radially superimposed accordion pleats in a tube which includes a forming structure to hold the tube in a distended tubular form while it is alternately contacted by a series of clamping fingers and a series of pleat folding fingers, which latter fingers function to move sections of the bag radially outwardly and longitudinally into a configuration constituting radially superimposed bands.
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