| 摘要 |
A method for processing a metal pipe 1 to make part of the metal pipe 1 in an axial direction thereof into a thick portion 10, the method includes: forming a shoulder as a stress concentration portion in an axial center of the metal pipe 1 to concentrate a stress thereon; setting the metal pipe 1 in an outer die 20; and forming the thick portion 10 by inserting an inner die 25 in the metal pipe 1 to provide space S for forming the thick portion 10 between the inner and outer dies 25 and 20, and applying the axial pressure to the metal pipe 1 to concentrate the stress on the shoulder to deform the shoulder after the forming and the setting, thereby forming the thick portion 10 from the deformed stress concentration portion as a starting point. |
