To efficiently manufacture a steel pillar having a thickness part excellent in dimensional accuracy.
An outer die 8 having an abutting stepped part 8a tightly fitted on the outside of a square pipe 2 on its one end and a diameter expanding part 8b which is arranged at an interval S1 with the outside of the square pipe 2 in the other part and an inner die 9 having an airtightly fitting part 9a which is tightly fitted into the inside of the diameter expanding part 8b of the outer die 8 and an inner die inserting part 9b which is inserted to a square pipe 2 at the interval S2 with the inside of the square pipe 2 are provided. One end of the square pipe 2 is heated and the outer die 8 is fitted on the outside of the heated end H, the airtightly fitting part 9a is tightly fitted into the diameter expanding part 8b of the outer die 8, the square pipe 2 is fixed, the inner die 9 is forced into the outer die 8 and pressing is executed. After forming the thick thickness part by increasing the thickness of the heated end H between the diameter expanding part 8b and the inner die inserting part 9b, the square pipe 2 is taken out and, after executing the refinement of crystals by rapid cooling and removal of residual stress by slow cooling, the steel pillar having a prescribed length is assembled by welding another square pipe at the end of the thick thickness part.
| JPH02155605 | WOOD PILLAR |
| JPH04203054 | COLUMN MEMBER STRUCTURE |
IWASAKI TAKAYUKI
RYU SHUNJI
KIRIYAMA SHINICHI
ASAHI CHEMICAL IND