| 摘要 |
PROBLEM TO BE SOLVED: To provide a hydroform process capable of achieving the hydroform without generating any cracks even when the internal shape of a die is not uniform. SOLUTION: When the internal shape of the die 1 is non-uniform, the imbalance of the local expansion ratio determined by the contact condition of an inner surface of the die with tube stock 2 in a seamed condition is mitigated by moving a split surface 8 of the die 1 to the side of the higher local expansion ratio. The local expansion ratio is determined as the ratio dB/dA of the non- contact circumferential length dA of the tube stock held by contact points between the tube stock 2 and the die 1 to the inner circumferential length of the die corresponding thereto.
|
