DEVICE FOR ADJUSTING ROLLING POSITIONS OF ROLLING ROLLS CONSTITUTING THREE-ROLL MANDREL MILL AND METHOD FOR MANUFACTURING SEAMLESS PIPES OR TUBES
A device for adjusting the rolling positions of rolling rolls and restraining poor roll-biting of the front edge part of a pipe material rolled by a three-roll mandrel mill includes pressing-down devices 1 (P 1 to P 6 ) for moving rolling rolls R 1 to R 6 in the rolling direction and a control unit 2 for controlling the pressing-down devices 1 . Immediately after the front edge part of a pipe material T has begun to be rolled by the rolling rolls disposed on at least one rolling stand of the rolling rolls R 1 to R 6 , the control unit 2 controls the pressing-down device 1 to move the rolling rolls in the closing direction. Preferably, the rolling rolls disposed on at least one rolling stand of the rolling rolls R 1 to R 6 in the closing direction are moved at a speed of 16 mm/sec or higher using the pressing-down device 1.
1 . A device for adjusting the rolling positions of rolling rolls disposed on at least one rolling stand constituting a three-roll mandrel mill, the device comprising:
a pressing-down device for moving the rolling rolls in the rolling direction; and
a control unit for controlling the pressing-down device,
wherein immediately after a front edge part of a pipe or tube material has begun to be rolled by the rolling rolls, the control unit controls the pressing-down device to move the rolling rolls in the closing direction.
2 . The device for adjusting the rolling positions of rolling rolls constituting a three-roll mandrel mill according to claim 1 , wherein the control unit moves the rolling rolls in the closing direction at a speed of 16 millimeters per second or higher by using the pressing-down device.
3 . A method for manufacturing seamless pipes or tubes, wherein a three-roll mandrel mill that adopts the device for adjusting the rolling positions of rolling rolls described in claim 1 is used.
4 . A device for adjusting the rolling positions of rolling rolls disposed on at least one rolling stand constituting a three-roll mandrel mill, the device comprising:
a pressing-down device for moving the rolling rolls in the rolling direction; and
a control unit for controlling the pressing-down device,
wherein immediately after a rear edge part of a pipe or tube material has begun to be rolled by the rolling rolls, the control unit controls the pressing-down device to move the rolling rolls in the closing direction.
5 . The device for adjusting the rolling positions of rolling rolls constituting a three-roll mandrel mill according to claim 4 , wherein the control unit moves the rolling rolls in the closing direction at a speed of 16 millimeters per second or higher by using the pressing-down device.
6 . A method for manufacturing seamless pipes or tubes, wherein a three-roll mandrel mill that adopts the device for adjusting the rolling positions of rolling rolls described in claim 4 is used.