Abstract: A method for folding a tube into radially superimposed accordian 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.

Abstract: A method for folding a tube into radially superimposed accordian 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.