This disclosure teaches a helically corrugated two-layer tube made of strips of sheetmetal or plastic and this disclosure teaches further an apparatus and a method for manufacture of the tube. A leading and a lagging margin of an inner strip are folded over each other along the path of the helix. A leading margin of an outer strip overlaps a lagging margin thereof along a corrugation. That corrugation is pressed along with a mating corrugation of the inner strip to form a head-shaped or snap-button-shaped fold whereby the inner and outer strips are united.
A readily adjustable machine which continuously produces corrugated flexible metal tubing from very light gauge metal and of various diameters. A warping ring receives therewithin a longitudinally corrugated narrow strip of formable metal of light gauge and warps the same helically to produce convolutions by means of a helical warping surface which extends into one of the longitudinal corrugations. The size of the tube produced can be varied by merely substituting a warping ring of a different size. A uniquely shaped pair of die-forming rollers have lock-seam forming surfaces which are adjustable relative to each other to provide variation in the degree to which the seam will permit and withstand axial torque. The lock seam is constructed to be symmetrical about the neutral axis of the corrugation and about the slope line of the common corrugation leg of adjacent convolutions which it constitutes. The lock is provided by its radially extending deformations in its longitudinal medial portions and terminal portions, with intermediate portions therebetween extending at about 60 degrees thereto. The terminal portions extend around the bottoms of each of the U-shaped seam elements to further lock them in place. A flying saw automatically cuts off predetermined lengths of the tubing. The length of the sections to be cut may be varied by merely re-positioning a movable switch in the path of the tube. The tube has a unique lock-seam which is constructed to withstand greater flexing, greater axial twist and more stress without damage and without opening, and is stronger.
A strip of very thin flexible material has continuous longitudinal corrugations in the form of curved ridges and hollows, and may be curled helically to form a flexible tube. The strip has a first marginal ridge with a radius of curvature smaller than that of all other ridges, and a second marginal ridge with a radius of curvature larger than that of all other ridges. As the strip is curled with the first marginal ridge overlying a first intermediate ridge and the second marginal ridge underlying a second intermediate ridge, the marginal ridges are respectively spread over and closed under the intermediate ridges to conform to the curvature thereof.
A bellows pipe construction and method for manufacturing are disclosed wherein helically wound coils of logitudinally corrugated strip are joined with an interlocking seam. Thereafter, the interlocking seam is deformed to position the edges of the strip in substantial parallelism with the axis of the pipe. The resulting pipe can be extended or shortened for installation and will further adjust and accommodate ground movement without substantial loss of strength.
A pipe formed by a helically coiled strip of ductile sheet metal of uniform width connected along its longitudinally extending edges by a seam, which seam is formed by the marginal portions of the strip along said edges. Said marginal portions are formed with parallel return bends extending longitudinally of said edges, which bends are in adjacent opposed relation and which marginal portions include flattened loops extending to the same side of said pipe from approximately one of said bends to the other with one of said loops enclosed within the other, and the said marginal portions are bent along a line spaced from and parallel with said bends to generally V-shape in cross sectional contour transversely of said marginal portions, whereby said bends are positioned in one of the sides of said V spaced from its apex with flattened portions of said loops extending across and to opposite sides of said apex.
A readily adjustable machine which continuously produces corrugated flexible metal tubing from very light gauge metal and of various diameters. A warping ring receives therewithin a longitudinally corrugated narrow strip of formable metal of light gauge and warps the same helically to produce convolutions by means of a helical warping surface which extends into one of the longitudinal corrugations. The size of the tube produced can be varied by merely substituting a warping ring of a different size. A uniquely shaped pair of die-forming rollers have lock-seam forming surfaces which are adjustable relative to each other to provide variation in the degree to which the seam will permit and withstand axial torque. The lock seam is constructed to be symmetrical about the neutral axis of the corrugation and about the slope line of the common corrugation leg of adjacent convolutions which it constitutes. The lock is provided by its radially extending deformations in its longitudinal medial portions and terminal portions, with intermediate portions therebetween extending at about 60.degree. thereto. The terminal portions extend around the bottoms of each of the U-shaped seam elements to further lock them in place. A flying saw automatically cuts off predetermined lengths of the tubing. The length of the sections to be cut may be varied by merely re-positioning a movable switch in the path of the tube. The tube has a unique lock-seam which is constructed to withstand greater flexing, greater axial twist and more stress without damage and without opening, and is stronger.
