COLD DIAMETER REDUCTION PRESS MOLDING METHOD OF METAL PIPE AND METAL PIPE MOLDED BY THAT METHOD

摘要

A cold diameter reduction press molding method of a metal pipe comprising a diameter reduction molding process for reducing the outer circumferential length of an original metal pipe having a noncircular transverse section as compared with the original outer circumferential length while press molding the original pipe to have a transverse section different from that of the original pipe; and a cold diameter reduction press molding method characterized by comprising a process for premolding an original metal pipe having a circular transverse section into a pipe having a transverse section different from that of the original pipe by roll molding using a premolding roll or first press molding using a premolding die, and a diameter reduction molding process for reducing the outer circumferential length of a premolded metal pipe as compared with that of the original metal pipe while remolding the premolded metal pipe to have a transverse section different from that of the premolded metal pipe by second press using a molding die.