| CPC B21B 1/16 (2013.01) [B21B 19/02 (2013.01); B21B 19/10 (2013.01); B21B 27/021 (2013.01)] | 20 Claims |
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1. A rolling mill for diameter reducing rolling comprising:
three or more rolling rolls aligned along a circumferential direction of a material to be rolled made of a pipe or bar material, and arranged such that each rotary shaft of the rolling rolls is skewed with respect to a pass line of the material to be rolled, at least one rolling roll from among the three or more rolling rolls being configured as a drive roll that is rotationally driven, and
wherein the three or more rolling rolls are configured to pass the material to be rolled through between the three or more rolling rolls while rotating the material to undergo the diameter reducing rolling,
wherein at least one rolling roll from among the three or more rolling rolls is smaller in roll diameter than at least one other rolling roll; and
wherein, among the three or more rolling rolls, at least one rolling roll having a maximum roll diameter is defined as a maximum diameter rolling roll and at least one rolling roll smaller in diameter than the maximum diameter rolling roll is defined as a small diameter rolling roll, and the small diameter rolling roll has a roll diameter greater than or equal to 65% and equal to or less than 85% of the roll diameter of the maximum diameter rolling roll.
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