| 摘要 |
PROBLEM TO BE SOLVED: To provide a molding method for a bellows tube of such a size and shape that its outer diameter ratio between a peak and a bottom exceeds the allowable elongation percentage of material, achieving such a large ratio between a maximum peak diameter and a minimum root diameter of more than 2.0:1.0 up to 5.0:1.0. SOLUTION: The method uses a clad tube 18 formed by bonding an inner tube and an outer tube together as a material tube. The outer diameter of the clad tube 18 is a nearly intermediate one between the peak outer diameter and the root outer diameter. The intermediate outer diameter tube is reduced to the root outer diameter by turning processing, and then a wall-thinning process by rolling is applied on the part with a diameter reduced by forming rollers for turning processing 20A, 20B. After that, the remaining intermediate outer diameter part is bulged into a peak by reducing wall thickness by a hydraulic bulge process. COPYRIGHT: (C)2003,JPO
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