| 摘要 |
PROBLEM TO BE SOLVED: To provide a mandrel mill capable of manufacturing a pipe free from a damage such as necking. SOLUTION: The mandrel mill is constituted of a plurality of grooved-roll stands consecutively arranged. A mandrel bar 3 is placed in a roll groove array formed of the grooved roll stands and a pipe is continuously rolled and elongated. In this case, a roll groove 4 of at least a first stand and a second stand is arranged so as to satisfy following formulae (1) to (4): (1) b≤10a+1.5, (2) b≥10a-0.2, (3) b≤-a+1.5, (4) b≥-a+1.15, wherein a=S/R1 and b=C/(R1-S). COPYRIGHT: (C)2008,JPO&INPIT
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