| 摘要 |
PROBLEM TO BE SOLVED: To prevent a perforated fault. SOLUTION: This method for rolling a pipe by a mandrel mill can be used to satisfy the following conditions (1) and (2); (1) in at least either the first or the second pilger roll stand from the upstream toward the downstream, rolling should be performed under the condition that a parameter s1 regulated by an equation: s1=-213r+Ψby the draft rate r of a wall thickness in the center portion of a groove bottom and the average contacting angleΨof a roll pilger is made more than -52.0; and (2) in at least either the third or the fourth pilger roll stand from the upstream toward the downstream, rolling should be performed under the condition that a parameter s2 regulated by an equation: s2=3.6r+rQP by the draft rate r of the wall thickness in the center portion of the groove bottom and the draft rate rQP of the wall thickness in the maximum portion of a draft amount in the wall thickness of the roll pilger is made less than 1.49.
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