Device for adjusting rolling positions of rolling rolls constituting three-roll mandrel mill and method for manufacturing seamless pipes or tubes

Abstract

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.