| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method for a strength member for a car body, by which, even when a material having a big Bauschinger effect is used for a metallic tube body, the strength of the strength member is enhanced without deteriorating the proof stress of the member. SOLUTION: After giving a compressive strain other than a plane compressive strain to a tube body 1, the wall thickness of a designated portion of the tube body is increased more than the initial wall thickness, by forming the tube body 1 into such a shape that a cross section in the direction perpendicular to the longitudinal direction of the body is polygon of rectangle or more and has a perimeter not exceeding the initial cross sectional perimeter, while keeping a hydraulic pressure so as not to cause a pipe expansion. Thus, even when the material having a big Bauschinger effect is used for the tube body 1, a compressive strain is given to a strength body A for a car body to improve the strength of the member A without deteriorating the proof stress of the member comparing with the case in which the member is elongated and deformed. COPYRIGHT: (C)2005,JPO&NCIPI
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