Nippon Steel & Sumkin Stainless Steel Corporation

Mitsuhiro Fujinaga

Junichi Hamada

Shuji Yamamoto

Atsuhisa Yakawa

A method of increasing the thickness of a tube which increases a thickness of an end part of a tube without a burr being formed, comprising placing a tubebetween a dieand mandrelin the state with a space for increasing the thickness between a small diameter partof the mandreland a first end partof a tubeand between a large diameter hole partC of the dieand a second end partof the tube, using a first upsetting punchand a second upsetting punchto respectively process the first end partand the second end partof the tube, pulling out the mandrelfrom the tubein the state with the second upsetting punchconstraining the second end partof the tube, and using the first upsetting punchto push up the first end partof the tubeto take out the tubefrom the die

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Tokyo, Japan

Mitsuhiro Fujinaga