| 摘要 |
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.
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