Steel plate manufacturing facility and manufacturing method

Abstract

A facility is provided for manufacturing a steel plate excellent in steel plate shape and mechanical property while setting low cooling-water spraying performance in a descaling step and achieving uniform cooling in a cooling step. Specifically, a hot rolling mill 3 , a first hot leveler 5 , a descaler 4 , and cooling equipment 6 are arranged in that order from the upstream side in a conveying direction. A pressure P [MPa] at the point of impact of cooling water sprayed from the descaler to each surface of a steel plate 1 is greater than or equal to 1.5 MPa.

1 . A steel plate manufacturing facility comprising:
 a hot rolling mill, a hot leveler, a descaler, and cooling equipment arranged in that order from the upstream side in a conveying direction, wherein a pressure P at the point of impact of cooling water sprayed from the descaler to each surface of a steel plate is greater than or equal to 1.5 MPa.   
     
     
         2 . The steel plate manufacturing facility according to  claim 1 , wherein when V [m/s] denotes the conveying velocity from the descaler to the cooling equipment and T [K] denotes the temperature of the steel plate before cooling, the distance L [m] between the descaler and the cooling equipment satisfies the expression L≦V×5×10 −9 ×exp(25000/T). 
     
     
         3 . The steel plate manufacturing facility according to  claim 1 , wherein the components are arranged such that the distance L between the descaler and the cooling equipment is less than or equal to 12 m. 
     
     
         4 . The steel plate manufacturing facility according to  claim 1 , wherein the distance H between each spraying nozzle of the descaler and each surface of the steel plate is greater than or equal to 40 mm and less than or equal to 140 mm. 
     
     
         5 . The steel plate manufacturing facility according to  claim 1 , wherein the cooling equipment includes a header supplying cooling water to the upper surface of the steel plate, cooling water spraying nozzles extending from the header and spraying rod-like cooling water, and a dividing plate disposed between the steel plate and the header, and the dividing plate includes a plurality of water supply inlets receiving the lower ends of the cooling water spraying nozzles and a plurality of drain outlets draining the cooling water supplied to the upper surface of the steel plate onto the dividing plate. 
     
     
         6 . A steel plate manufacturing method including a hot rolling step, a hot leveling step, and a cooling step performed in that order to manufacture a steel plate, the method comprising:
 a descaling step of spraying cooling water to each surface of the steel plate at a pressure at the point of impact of 1.5 MPa or higher, the descaling step being performed between the hot leveling step and the cooling step.   
     
     
         7 . The steel plate manufacturing method according to  claim 6 , wherein when T [K] denotes the temperature of the steel plate before cooling, the period of time t [s] between the completion of the descaling step and the start of the cooling step satisfies the expression t≦5×10 −9 +exp(25000/T).