US 6,145,732 AGranted

Cylindrical helical seamed tube and method and apparatus therefore

AssigneeEdward A. Akins

InventorsEdward A. Akins, George Harms

Life of this patent

Estimating the term…

Loading patent…

Abstract

A cylindrical helical seamed metal tube wherein the seam thereof is at an angle of between 1 and 25 degrees with respect to the axis of the tube. A method of making the tube comprises the steps of continuously feeding the metal strip into a tubing former to form the metal strip into a helical tube with the leading and trailing edges juxtaposed, the feeding such that the strip longitudinal axis is at a substantially constant acute angle with respect to the tube longitudinal axis of between 1 and 25 degrees. After the tube is substantially formed, applying pressure on at least the leading edge, leading portion, trailing edge and trailing portion in the direction of the cylindrical wall such that same substantially conform to the cylindrical wall. The juxtaposed leading and trailing edges are fused together to form a fused seam, and maintained in a juxtaposed position until the seam cools sufficiently to maintain the juxtaposed position. An apparatus for making the tube is also provided.

Claims11

Dependent claims

An apparatus for making a cylindrical helical seamed tube, having a tube longitudinal axis, from a metal strip having a strip longitudinal axis and parallel longitudinal edges being a leading edge adjacent a leading portion of said metal strip and a trailing edge adjacent a trailing portion of said metal strip, said apparatus comprising:

a tubing former operable to form said metal strip into a helical tube with said leading and trailing edges juxtaposed, said tubing former defining an aperture with a cylindrical wall;
means for continuously feeding said metal strip into said tubing former, said means for continuously feeding operative to maintain said strip longitudinal axis at a substantially constant acute angle with respect to said tube longitudinal axis, said acute angle being between 1 and 25 degrees;
first means to apply pressure, after said tube is substantially formed within said tubing former with said leading and trailing edges juxtaposed, on at least said leading edge, leading portion, trailing edge and trailing portion in the direction of said cylindrical wall such that said leading edge, leading portion, trailing edge and trailing portion substantially conform to said cylindrical wall;
means for fusing said juxtaposed leading and trailing edges together to form a seam;
and
means for maintaining said leading and trailing edges in a juxtaposed position until said seam cools sufficiently to maintain said juxtaposed position.

3 more elements

Dependencies are inferred from the claim text.