Rolling method of shaped steel, production line of shaped steel, and production method of shaped steel

Abstract

Regarding each rolling mill, a rolling torque Gi before biting into a downstream stand is stored, the peripheral velocity of a most downstream stand Rn is controlled to be Gn−1=Gn−1* after biting into Rn, and a rolling torque Gn** of Rn after tension is stabilized is stored. After that, the peripheral velocity of a rolling mill Ri is controlled to be Gi=Gi* toward an upstream side, and the peripheral velocity of a rolling mill Rk at a downstream side of the rolling mill Ri is controlled to keep Gk=Gk** (k=i+1 to n) so that a rolling torque of a most upstream rolling mill R1 becomes equal to a stored G1*. Stabilization of material passage and improvement in accuracy of a product dimension are enabled by controlling tension between stands with high accuracy by using a simple control system without using table values or the like by each rolling condition even under a condition where a distance between stands is short.

1 . A rolling method of shaped steel which performs reduction between a horizontal roll side surface and a vertical roll peripheral surface by using one piece or more of rolling mill when tandem rolling is carried out in a rolling mill train formed of n-pieces of rolling mills of at least three pieces or more, the rolling method comprising:
 a first control step of fixing the peripheral velocity of a rolling mill Ri of the rolling mill train after a material to be rolled is bitten into the rolling mill Ri and before the material to be rolled is bitten into a rolling mill Ri+1 positioning at a downstream side of the rolling mill Ri, and storing a rolling torque Gi of the rolling mill Ri at that time as Gi* regarding each rolling mill Ri, and   controlling the peripheral velocity of a most downstream rolling mill Rn of the rolling mill train after the material to be rolled is bitten into the rolling mill Rn so that a rolling torque Gn−1 of a rolling mill Rn−1 positioning at an upstream side of the rolling mill Rn becomes equal to Gn−1* which is stored as a rolling torque of the rolling mill Rn−1 before the material to be rolled is bitten into the rolling mill Rn;   a second control step of storing a rolling torque Gn** of the rolling mill Rn after the first control step, and   subsequently, controlling the peripheral velocity of the rolling mill Rn−1 so that a rolling torque Gn−2 of a rolling mill Rn−2 positioning at an upstream side of the rolling mill Rn−1 becomes equal to Gn−2* which is stored as a rolling torque of the rolling mill Rn−2 before the material to be rolled is bitten into the rolling mill Rn−1, and controlling the peripheral velocity of the rolling mill Rn so that a rolling torque Gn of the rolling mill Rn becomes equal to the stored rolling torque Gn**, wherein   the second control step is applied to all of the rolling mills Ri, and the peripheral velocity of each rolling mill Ri of the rolling mill train is controlled so that a rolling torque G1 of a most upstream rolling mill R1 becomes equal to G1* which is stored as a rolling torque of the rolling mill R1 before the material to be rolled is bitten into a rolling mill R2 positioning at a downstream side of the rolling mill R1,   here, i is an arbitrary integer number from one to n, and n is an integer number of three or more.   
     
     
         2 . The rolling method of the shaped steel according to  claim 1 , wherein
 the control is performed by using a torque arm coefficient (G/P) which is a value where a rolling torque of each rolling mill is divided by a rolling load of the rolling mill in place of a value of the rolling torque of each rolling mill of the rolling mill train.   
     
     
         3 . The rolling method of the shaped steel according to  claim 1 , wherein
 after controlling all of the peripheral velocity of the respective rolling mills Ri of the rolling mill train, rolling is carried out by fixing a ratio of the peripheral velocity of the respective rolling mills Ri.   
     
     
         4 . The rolling method of the shaped steel according to  claim 3 , wherein
 a rolling speed of the most downstream rolling mill Rn of the rolling mill train is increased to a desired speed under a state where the ratio of the peripheral velocity of the respective rolling mills Ri is fixed.   
     
     
         5 . A production line of shaped steel having a constitution where a rolling mill train formed of n-pieces of rolling mills of at least three pieces or more and at least one piece or more of rolling mills or a rolling mill train are tandem arranged in this order and carrying out reduction between a horizontal roll side surface and a vertical roll peripheral surface by using one piece or more of rolling mill, wherein
 in the production line, no-tension control of a material to be rolled is performed at the upstream rolling mill train, the upstream rolling mill train and the downstream rolling mills or rolling mill train are arranged in a state where there is a sufficient distance for the material to be rolled to be bitten into the downstream rolling mills or rolling mill train after the no-tension control is completed, and   the rolling method of the shaped steel according to  claim 1  is independently performed at the upstream rolling mill train and the downstream rolling mills or rolling mill train.   
     
     
         6 . A production method of shaped steel produced by carrying out reduction between a horizontal roll side surface and a vertical roll peripheral surface, the production method comprising:
 a first control step of fixing the peripheral velocity of a rolling mill Ri after a material to be rolled is bitten into the rolling mill Ri and before the material to be rolled is bitten into a rolling mill Ri+1 positioning at a downstream side of the rolling mill Ri, and storing a rolling torque Gi of the rolling mill Ri at that time as Gi* regarding each rolling mill Ri in a rolling mill train formed of n-pieces of rolling mills of at least three pieces or more, and   controlling the peripheral velocity of a most downstream rolling mill Rn of the rolling mill train after the material to be rolled is bitten into the rolling mill Rn so that a rolling torque Gn−1 of a rolling mill Rn−1 positioning at an upstream side of the rolling mill Rn becomes equal to Gn−1* which is stored as a rolling torque of the rolling mill Rn−1 before the material to be rolled is bitten into the rolling mill Rn;   a second control step of storing a rolling torque Gn** of the rolling mill Rn after the first control step, and   subsequently, controlling the peripheral velocity of the rolling mill Rn−1 so that a rolling torque Gn−2 of a rolling mill Rn−2 positioning at an upstream side of the rolling mill Rn−1 becomes equal to Gn−2* which is stored as a rolling torque of the rolling mill Rn−2 before the material to be rolled is bitten into the rolling mill Rn−1, and controlling the peripheral velocity of the rolling mill Rn so that a rolling torque Gn of the rolling mill Rn becomes equal to the stored rolling torque Gn**, wherein   the shaped steel is produced by applying the second control step to all of the rolling mills Ri, and controlling the peripheral velocity of each rolling mill Ri of the rolling mill train so that a rolling torque G1 of a most upstream rolling mill R1 becomes equal to G1* which is stored as a rolling torque of the rolling mill R1 before the material to be rolled is bitten into a rolling mill R2 positioning at a downstream side of the rolling mill R1.   
     
     
         7 . The rolling method of the shaped steel according to  claim 2 , wherein
 after controlling all of the peripheral velocity of the respective rolling mills Ri of the rolling mill train, rolling is carried out by fixing a ratio of the peripheral velocity of the respective rolling mills Ri.   
     
     
         8 . A production line of shaped steel having a constitution where a rolling mill train formed of n-pieces of rolling mills of at least three pieces or more and at least one piece or more of rolling mills or a rolling mill train are tandem arranged in this order and carrying out reduction between a horizontal roll side surface and a vertical roll peripheral surface by using one piece or more of rolling mill, wherein
 in the production line, no-tension control of a material to be rolled is performed at the upstream rolling mill train, the upstream rolling mill train and the downstream rolling mills or rolling mill train are arranged in a state where there is a sufficient distance for the material to be rolled to be bitten into the downstream rolling mills or rolling mill train after the no-tension control is completed, and   the rolling method of the shaped steel according to  claim 2  is independently performed at the upstream rolling mill train and the downstream rolling mills or rolling mill train.   
     
     
         9 . A production line of shaped steel having a constitution where a rolling mill train formed of n-pieces of rolling mills of at least three pieces or more and at least one piece or more of rolling mills or a rolling mill train are tandem arranged in this order and carrying out reduction between a horizontal roll side surface and a vertical roll peripheral surface by using one piece or more of rolling mill, wherein
 in the production line, no-tension control of a material to be rolled is performed at the upstream rolling mill train, the upstream rolling mill train and the downstream rolling mills or rolling mill train are arranged in a state where there is a sufficient distance for the material to be rolled to be bitten into the downstream rolling mills or rolling mill train after the no-tension control is completed, and   the rolling method of the shaped steel according to  claim 3  is independently performed at the upstream rolling mill train and the downstream rolling mills or rolling mill train.   
     
     
         10 . A production line of shaped steel having a constitution where a rolling mill train formed of n-pieces of rolling mills of at least three pieces or more and at least one piece or more of rolling mills or a rolling mill train are tandem arranged in this order and carrying out reduction between a horizontal roll side surface and a vertical roll peripheral surface by using one piece or more of rolling mill, wherein
 in the production line, no-tension control of a material to be rolled is performed at the upstream rolling mill train, the upstream rolling mill train and the downstream rolling mills or rolling mill train are arranged in a state where there is a sufficient distance for the material to be rolled to be bitten into the downstream rolling mills or rolling mill train after the no-tension control is completed, and   the rolling method of the shaped steel according to  claim 4  is independently performed at the upstream rolling mill train and the downstream rolling mills or rolling mill train.