| 摘要 |
<p>Small diameter metal tubes are manufactured with good precision and high production efficiency by using a large diameter roll in which rolls having diameters that are clearly larger than the outer diameter of the metal tube being manufactured are disposed. A pair of large diameter side rolls is used, the rolls being designed so that the outer diameter ratio f2/ f1 of the outer diameter f2 of the forming roll to the outer diameter f1 of the metal tube being manufactured is 10 or more, preferably 25 or more. After forming a metal band into a cylindrical shape in a single stand, the edges of the metal band are brought together and welded. A three roll-type or a four roll-type can be used for the large diameter side roll.</p> |
