| 摘要 |
This seamless metal tube fabrication method is provided with the following: a step for determining whether to use the group of front stage stands for reducing the outer diameter or reducing the thickness of the hollow raw pipe, and a step in which, on the basis of that determination, the hollow raw pipe into which a mandrel bar has been inserted is drawn and rolled. In the drawing-rolling step, in the case where the group of front stage stands is to be used to reduce the outer diameter of the pipe, at the group of front stage stands, the hollow raw pipe is rolled while the inner surface of the hollow raw pipe remains in a state of non-contact with the mandrel bar, and, in the group of rear stage stands, the hollow raw pipe is rolled while the inner surface of the hollow raw pipe remains in a state of contact with the mandrel bar. |
