| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for bending a high strength steel pipe so as to form a flat cross section at the bent portion. SOLUTION: A high strength steel pipe is used as a blank pipe. The press bending is carried out on the blank pipe by pushing a press bending die having the caliber diameter larger than the outside diameter of the blank pipe while applying a tensional force to the blank pipe in its axial direction. By this operation, the pipe having the flat cross section at the bent portion can be formed by one press bending operation. The tensional force to be applied is 3% or higher of the yield strength of the blank pipe, preferably 20% or higher. Further, it is preferable that the caliber diameter of the press bending die is 1.1 times or more of the outside diameter of the blank pipe. COPYRIGHT: (C)2009,JPO&INPIT
|
