Nisshin Steel Co., Ltd.

Ryuji Tanoue

Naofumi Nakamura

Hirokazu Sasaki

Jun Kurobe

Yusuke Hirose

Toshiro Yamada

Shigeo Matsubara

Iwao Katayama

Yukimi Miwa

A method of manufacturing a rectangular tube having a stepped portion includes: forming V-shaped grooves on a rectangular tube at surfaces of an end thereof in a direction parallel to a longitudinal direction thereof; and pressing each of the surfaces having the V-shaped grooves formed thereon with a rotating roll from outside to inside, whereby the end of the rectangular tube is radially reduced.

Method of manufacturing rectangular tube having stepped portion

A method of manufacturing a rectangular tube having a stepped portion includes: forming V-shaped grooves on a rectangular tube at surfaces of an end thereof in a direction parallel to a longitudinal direction thereof; and pressing each of the surfaces having the V-shaped grooves formed thereon from outside to inside, whereby the end of the rectangular tube is radially reduced.

A zirconia oxygen sensor for measuring oxygen potential in the molten bath of a metal or alloy having a melting point of 350-550.degree. C., which comprises a reference electrode which is of a substance having a melting point of the same level as or lower than the metal or alloy of which the oxygen potential is to be measured and being liquid at the measurement temperature and is open to the atmosphere, a vessel of a zirconia solid electrolyte containing 5-10% yttria or 10-20% of calcium oxide (CaO) and a lead wire which connects the reference electrode and said molten metal or alloy and its use are disclosed.

Zirconia oxygen sensor

Growing community of inventors

Sakai, Japan

Ryuji Tanoue