Patent ID: 7661283
Filing Date: 2010-02-16
Classification: B21C,B21D,Y10T

Abstract:
1. A bulging method for performing a forming process on a hollow member by introducing a fluid under pressure thereinto, comprising the steps of: gripping said hollow member at opposite ends thereof with rods of first holding mechanisms, wherein said rods are movable back and forth and have fluid pressure passages defined therein; introducing a fluid under pressure into said hollow member gripped by said rods to expand said hollow member, and stopping the expansion of said hollow member by contact with a tube expanding die; displacing said first holding mechanisms from said tube expanding die to a preforming die with displacing mechanisms to deliver the expanded hollow member to said preforming die; preforming said hollow member with said preforming die; gripping said hollow member at the opposite ends thereof with rods of second holding mechanisms, wherein said rods are movable back and forth and have fluid pressure passages defined therein, displacing said second holding mechanisms from said preforming die to a main forming die with displacing mechanisms to deliver the preformed hollow member to said main forming die; and forming said hollow member into a product shape with said main forming die.