| 摘要 |
PROBLEM TO BE SOLVED: To provide a cold-forming method for a metallic tube of which the wall thickness in the cross section is uneven so as to be different in a predetermined portion in the circumferential direction and in other portions, and to provide a metallic tube formed thereby. SOLUTION: The cold-forming method for the metallic tube includes: a preforming step of forming an original tube composed of a metallic tube into a metallic tube having an elliptical, oblong, square or polygonal section by using any one of a performing roll, a performing roller, and a performing die; and a constriction forming step of changing the cross-sectional shape into another cross-sectional shape while reducing the outer peripheral length of the cross section of the preformed metal tube by using a constriction die so that the wall thickness of the cross section of the metallic tube is uneven so as to be different in a predetermined portion in the circumferential direction and in other portions, and a metallic tube formed thereby is also provided. COPYRIGHT: (C)2006,JPO&NCIPI
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