| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a bumper stay 21 in the end parts of a shaft part 22 of which mounting flanges 23, 24 having long holes 25, 26 for mounting are formed by a simple method. SOLUTION: Circular holes 28, 29 penetrating through the tube wall are formed in the end parts of a tube stock 27 consisting of an aluminum alloy extruded material and the flanges 23, 24 are formed by expanding the end parts of the tube stock 27 including the parts of the holes by electromagnetic forming. Approximately elliptic holes 25, 26 spread in the peripheral direction are formed on the flanges 23, 24. The flanges are strengthened by work hardening action owing to deformation. COPYRIGHT: (C)2004,JPO&NCIPI
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