| 摘要 |
The object is to raise the yield by greatly eliminating the disposed amounts of the tube ends, prevent wrinkles due to closing the mold while applying internal pressure, cutting the plurality of steps of hydroforming and pre-processing of the tube ends, cutting the mold costs by simplifying the mold mechanism, and obtaining a hydroformed product formed with a flange along its entire length. For this reason, the present invention provides a hydroforming method which places a metal tube to a lower mold in the state with the tube ends sticking out from it and injects a pressurizing fluid into the metal tube through the inside of a seal punch and gradually presses seal punches against tube ends of the metal tube to apply a predetermined pressing force and fill the inside of the metal tube with the pressurizing fluid to apply a predetermined internal pressure, next, in the state with the internal pressure and pressing force applied, lowers the upper mold and closes the mold so as to deform the tube and end the processing in the state with the tube ends sticking out from the mold, and, further, boosting the internal pressure in the metal tube after closing the mold and ending the forming operation and a hydroformed product processed using these methods and having a flange across the entire length in the longitudinal direction.
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