| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem that in the conventional flattening technique, in order to prevent the deterioration of flatness and a break in edge parts in a flattening part, the use of a core is needed and the deterioration of working efficiency is caused. Ž<P>SOLUTION: Liquid is poured into the inside of the inner periphery of a metallic tube 10 and, under the state where internal pressure is loaded by the pressure of that liquid, flattening work is applied until the height h of flatness becomes a prescribed height H of the flatness of a product of ≤0.5 times the outside diameter D of the metal tube before the flattening work. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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