To improve manufacturing efficiency by stably running a tube stock while restricting bend of the tube stock by a press roller between a squeeze roll and a pre-forming stand when forming in line a special shape tube having a helical rugged pattern.
After both end parts in a plate width of a metal band of an open tubular shape are butted by he squeeze roll, both plate width end parts butted are welded, a tube stock is passed through a pre-forming stand integrating a pre-forming roll to indent plural recessed parts to a peripheral face of the tube stock in the circumferential direction and a forming stand integrating a forming roll to be fitted into the recessed part, plural helical rugged patterns are formed to the circumferential direction of the tube stock, at this time, a press roll apparatus is arranged between the squeeze roll and the pre-forming stand, bend of the tube stock is restricted by pressing force of the press roll.
KUROBE ATSUSHI
NAKAKO TAKEFUMI
ASADA HIROSHI
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