Multiwall steel tube
OwnerYutaka Jinnouchi, Yusuke Yamashita +1inventors
InventorsYutaka Jinnouchi, Yusuke Yamashita, Jirou Suzuki
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Abstract
This aims to provide a multiplex-wound steel pipe which can be sufficiently supplied in its manufacturing procedure with copper needed when brazed, which has its surface freed from any re-solidification of copper, and which has a satisfactory fillet formed at its seamed portion. A steel plate includes one face having a copper-plated film thickness (t1) and the other face having a copper-plated film thickness (t2) such that the copper-plated film thickness (t1) of that one face is smaller than the copper-plated film thickness (t2) of the other face, and such that the steel plate is formed into a tubular shape having that one face positioned on the outer side face of the multiplex-wound steel pipe.
Claims9
A multiwall steel tube formed by winding a steel sheet having opposite first and second surfaces respectively coated with copper films by plating round a forming roll in a tube and bonding together the layers of the steel sheet by brazing, wherein the copper film coating the first surface has a thickness t1, the copper film coating the second surface has a thickness t2 greater than the thickness t1, and the steel sheet is wound such that the first surface faces outside.
A multiwall steel tube manufacturing method of manufacturing a multiwall steel tube formed by winding a steel sheet having copper-plated surfaces round a forming roll in a tube and bonding together the layers of the steel sheet by brazing, said method comprising the steps of:
- preparing a steel sheet having a first surface coated with a copper film of a thickness t1 and a second surface of a thickness t2 greater than the thickness t1;
- winding the steel sheet round a forming roll in a steel tube such that the first surface faces outside;
- and
- bonding together the layers of the steel sheet of the steel tube by brazing that heats the steel tube at a temperature not lower than the molting point of copper in a reducing atmosphere.
Dependencies are inferred from the claim text.