| 摘要 |
PROBLEM TO BE SOLVED: To efficiently suppress stripping failure and uneven thickness in consideration of misalignment between a core of a mandrel mill and an axial core of a pipe material during rolling. SOLUTION: This mandrel mill rolls a seamless pipe with a value (F/P) of thrusting force of a bar F/pressing force of the bar P to be in the range of 0.25-0.45 at No.1-3 stands thereof. Accordingly, the occurrence of uneven thickness or stripping failure is roughly determined, and rolling is carried out with F/P on at least No.1-3 stands to be in the most adequate range in consideration of misalignment between the core of the mandrel mill and the axial core of the pipe material during rolling. Thus stripping failure and uneven thickness are effectively suppressed. COPYRIGHT: (C)2004,JPO
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