To provide a method for producing a copper pipe by which a small diameter copper pipe having an outer diameter of ≤ 10 mm produced by applying a cold-working of a large reducing area ratio of ≥ 99% to an extruded blank pipe hardly causes crack when the pipe is further subjected to pipe-expanding work or pipe-shrinking work having a large expanding ratio or shrinking ratio.
When producing the small diameter copper pipe of an outer diameter of ≤ 10 mm which is used after being subjected to the pipe-expanding work or the pipe-shrinking work, on the way of the cold-working, an intermediate annealing of the copper pipe is performed and the copper pipe is tempered with the intermediate annealing, in the range of O to 1/8H in quality symbol of JIS and also, the area reducing ratio of the copper pipe in the cold-working to a finish annealing after the intermediate annealing, is made to be 10-95% to the extruded blank pipe.
ISOZAKI AKIO
NAKADOI JUNICHI
NIWA MICHIHIKO
SATO MASAHIKO
KOBAYASHI MAKOTO
SAKAHARA HISASHI
Makoto Suhara
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