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1. (WO2017154481) METHOD FOR MANUFACTURING DIFFERENT-THICKNESS STEEL PIPE, AND DIFFERENT-THICKNESS STEEL PIPE

Pub. No.:    WO/2017/154481    International Application No.:    PCT/JP2017/005278
Publication Date: Fri Sep 15 01:59:59 CEST 2017 International Filing Date: Wed Feb 15 00:59:59 CET 2017
IPC: B21C 37/16
B21D 39/20
B21J 5/08
Applicants: NIPPON STEEL & SUMITOMO METAL CORPORATION
新日鐵住金株式会社
Inventors: MIZUMURA Masaaki
水村 正昭
IGUCHI Keinosuke
井口 敬之助
ARITA Hidehiro
有田 英弘
Title: METHOD FOR MANUFACTURING DIFFERENT-THICKNESS STEEL PIPE, AND DIFFERENT-THICKNESS STEEL PIPE
Abstract:
This method for manufacturing a different-thickness steel pipe, which manufactures a different-thickness steel pipe from a hollow cylindrical element pipe, has: a locking step, wherein the element pipe is arranged inside a die and a plug is inserted from one end of the element pipe while movement of the element pipe in the lengthwise direction is restricted, thereby enlarging the outer shape of that one end and locking the element pipe in the die; and an ironing step, wherein the restriction of the element pipe is released and, while the locking of the element pipe is maintained, the plug is inserted farther toward the other end of the element pipe, thereby enlarging the inside shape while maintaining the outside shape of the element pipe and forming a thin section.