Roller leveler and metal sheet flattening method

Abstract

A roller leveler for flattening a metal sheet or plate having a cut-sheet form includes leveling rolls disposed in a staggered state on upper and lower sides of a pass line and configured to sandwich and flatten the metal sheet while pressing it therethrough, a hydraulic pressing cylinder for pressing the metal sheet via the leveling rolls, intermediate rolls set in contact with the respective leveling rolls from outside and larger in diameter than the leveling rolls, and a drive unit for rotating the intermediate rolls. The roller leveler causes the drive unit to rotate the intermediate rolls and transmits the driving force to the leveling rolls to pass the metal sheet while causing the pressing cylinder to press the metal sheet via the leveling rolls.

1 . A roller leveler for flattening a metal sheet having a cut-sheet form, the roller leveler comprising:
 a plurality of leveling rolls disposed in a staggered state on upper and lower sides of a pass line of the metal sheet to be flattened and configured to rotate to sandwich and flatten the metal sheet while passing the metal sheet therethrough;   a hydraulic pressing cylinder configured to press the metal sheet via the leveling rolls;   a plurality of intermediate rolls disposed outside the plurality of leveling rolls on the upper and lower sides and set in contact with the respective leveling rolls from outside, the intermediate rolls having a diameter larger than that of the leveling rolls; and   a drive unit configured to rotate the intermediate rolls,   wherein the roller leveler is configured to cause the drive unit to drive the intermediate rolls for rotation and cause a driving force therefrom to be transmitted to the leveling rolls to pass the metal sheet while causing the pressing cylinder to press the metal sheet via the leveling rolls.   
     
     
         2 . The roller leveler according to  claim 1 , further comprising:
 a pair of roll frames that support the leveling rolls and the intermediate rolls on the upper and lower sides, respectively, wherein one of the pair of frames is configured to be pressed by the pressing cylinder from a side opposite to the leveling rolls;   a plurality of hydraulic crowning cylinders arrayed in a width direction perpendicular to a pass direction of the metal sheet between one of the frames configured to be pressed by the pressing cylinder and a corresponding one of the roll frames; and   a control system configured to control flattening of the metal sheet,   wherein the control system is configured to perform control to cause the drive unit to drive the intermediate rolls for rotation and cause a driving force therefrom to be transmitted to the leveling rolls while causing the pressing cylinder to press the metal sheet via the leveling rolls, with the metal sheet being passed between the leveling rolls on the upper and lower sides, and   wherein the control system is configured to obtain lateral deflection amounts of the pair of frames, to calculate necessary tightening amounts of the respective hydraulic crowning cylinders necessary for compensating for the deflection amounts, and to control tightening of the respective hydraulic crowning cylinders based on the necessary tightening amounts.   
     
     
         3 . The roller leveler according to  claim 2 , wherein the control system is configured to calculate necessary tightening amounts of the respective hydraulic crowning cylinders necessary for compensating for compressive deformation of the pressing cylinder, the hydraulic crowning cylinders, the pair of roll frames, the intermediate rolls, and the leveling rolls based on information on the compressive deformation, and to control tightening of the respective hydraulic crowning cylinders based on a total value of the necessary tightening amounts necessary for compensating for the compressive deformation and the necessary tightening amounts necessary for compensating for the deflection amounts of the pair of frames. 
     
     
         4 . The roller leveler according to  claim 1 , wherein the intermediate rolls have a diameter 1.2 to 2 times as large as a diameter of the leveling rolls, and the leveling rolls have a pitch, on each of the upper and lower sides, 1.2 to 2 times as large as the diameter of the leveling rolls. 
     
     
         5 . The roller leveler according to  claim 1 , wherein the intermediate rolls are configured to be individually driven. 
     
     
         6 . The roller leveler according to  claim 1 , wherein a pressing amount to the metal sheet is reduced until a leading end of the metal sheet passes through an area where the leveling rolls are disposed, and then is set at a value necessary for flattening the metal sheet after the leading end of the metal sheet passes through the area where the leveling rolls are disposed. 
     
     
         7 . The roller leveler according to  claim 1 , wherein the metal sheet to be flattened is a steel sheet having a thickness of 2.0 to 25.4 mm and a yield stress of 400 to 1,800 MPa. 
     
     
         8 . A metal sheet flattening method of flattening a metal sheet having a cut-sheet form in a roller leveler, which includes
 a plurality of leveling rolls disposed in a staggered state on upper and lower sides of a   pass line of the metal sheet to be flattened and configured to rotate to sandwich and flatten the metal sheet while passing the metal sheet therethrough,   a hydraulic pressing cylinder configured to press the metal sheet via the leveling rolls,   a plurality of intermediate rolls disposed outside the plurality of leveling rolls on the upper and lower sides and set in contact with the respective leveling rolls from outside, the intermediate rolls having a diameter larger than that of the leveling rolls, and   a drive unit configured to rotate the intermediate rolls,   the method comprising:
 inserting the metal sheet between the leveling rolls on the upper and lower sides; 
   causing the pressing cylinder to press the metal sheet via the leveling rolls; and causing the drive unit to drive the intermediate rolls for rotation and causing a driving force therefrom to be transmitted to the leveling rolls to pass the metal sheet.   
     
     
         9 . The metal sheet flattening method which according to  claim 8 , wherein the roller leveler further includes
 a pair of roll frames that support the leveling rolls and the intermediate rolls on the upper and lower sides, respectively,   a pair of frames that support the pair of roll frames on the upper and lower sides, respectively, wherein one of the pair of frames is configured to be pressed by the pressing cylinder from a side opposite to the leveling rolls, metal sheet via one of the roll frames, the intermediate rolls, and the leveling rolls,   a plurality of hydraulic crowning cylinders arrayed in a width direction perpendicular to a pass direction of the metal sheet between one of the frames configured to be pressed by the pressing cylinder and a corresponding one of the roll frames,   the method further comprising:
 obtaining lateral deflection amounts of the pair of frames; calculating necessary tightening amounts of the respective hydraulic crowning cylinders necessary for compensating for the deflection amounts; and controlling tightening of the respective hydraulic crowning cylinders based on the necessary tightening amounts. 
   
     
     
         10 . The metal sheet flattening method according to  claim 9 , wherein the method comprises calculating necessary tightening amounts of the respective hydraulic crowning cylinders necessary for compensating for compressive deformation of the pressing cylinder, the hydraulic crowning cylinders, the pair of roll frames, the intermediate rolls, and the leveling rolls based on information on the compressive deformation; and controlling tightening of the respective hydraulic crowning cylinders based on a total value of the necessary tightening amounts necessary for compensating for the compressive deformation and the necessary tightening amounts necessary for compensating for the deflection amounts of the pair of frames. 
     
     
         11 . The metal sheet flattening method according to  claim 8 , wherein the intermediate rolls have a diameter 1.2 to 2 times as large as a diameter of the leveling rolls, and the leveling rolls have a pitch, on each of the upper and lower sides, 1.2 to 2 times as large as the diameter of the leveling rolls. 
     
     
         12 . The metal sheet flattening method according to  claim 8 , wherein the intermediate rolls are configured to be individually driven. 
     
     
         13 . The metal sheet flattening method according to  claim 8 , wherein a pressing amount to the metal sheet is reduced until a leading end of the metal sheet passes through an area where the leveling rolls are disposed, and then is set at a value necessary for flattening the metal sheet after the leading end of the metal sheet passes through the area where the leveling rolls are disposed. 
     
     
         14 . The metal sheet flattening method according to  claim 8 , wherein the metal sheet to be flattened is a steel sheet having a thickness of 2.0 to 25.4 mm and a yield stress of 400 to 1,800 MPa. 
     
     
         15 . The roller leveler according to  claim 1 , further comprising a plurality of backup rolls that back up the plurality of intermediate rolls on the upper and lower sides. 
     
     
         16 . The metal sheet flattening method according to  claim 8 , wherein the roller leveler further includes a plurality of backup rolls that back up the plurality of intermediate rolls on the upper and lower sides.