Hitachi, Ltd.

Shinji Fukuda

Masaki Murashita

Osamu Isshiki

Masayoshi Hashiura

Yutaka Kobayashi

Takashi Sato

Seizo Nakano

Takashi Satoh

Hideaki Kikuchi

Osamu Matsushima

Koji Goto

Sadao Nakagawa

Katsuro Ota

Hideo Kawamoto

Tokio Yamagiwa

Shigetaka Takeuchi

A laser welding device for welding a long sized tubular grounding unit includes a work head arranged to rotate around an outer circumference of two tubular members to be welded, a laser oscillator, and apparatus to transmit the laser beam from the oscillator in sychronism with rotation of the work head. In one embodiment the apparatus to transmit the laser beam includes an optical fiber.

Long-sized tubular grounding container unit for gas-insulated electrical

A welded metal container for a sheath 1 or 1A of gas insulated switch gear comprises a trunk pipe 2, 21 and a branch pipes 3, 31, 32 welded to the trunk pipe 2,21 by arc welding A or laser beam welding LB and flanges welded to the each end portion of the trunk pipe 2, 21 and branch pipes 3, 31, 32 by the laser beam welding. After the arc welding A, the ends of trunk pipe 1, 21 and branch pipes 3, 31, 32 are machined precisely and flanges 4a, 4b, 4c, 4d, 4f and 4g are welded to the end portions of the trunk pipe 2, 21 and branch pipes 3, 31, 32.

Structure of metal container having trunk pipe and branch pipe, and

A method for manufacturing a welded metal container by first arc welding a branch pipe to a trunk pipe. The arc welding of the pipes together causes both of the pipes to be thermally deformed. The end surfaces of the pipes are then cut by a laser cutting or mechanical cutting process so that the ends of the trunk pipe are in parallel and perpendicular to the end of the branch pipe. Subsequently flanges are laser welded to the ends of the pipes without further thermally deforming the pipes. The metal container made by this process can be used as a sheath for a gas insulated switch gear.

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Hitachi, Japan

Shinji Fukuda