| 摘要 |
<p>PURPOSE:To obtain a hot rolled steel sheet excellent in quality by dividing the groups of cooling-water spraying nozzles to be placed at the upper surface side of a sheet in the direction of sheet width to control the flow-rate density of cooling water, and increasing the density from the central part of sheet to the end parts. CONSTITUTION:Nozzle groups 2 to be placed at the upper-surface side of a steel sheet 1, are arranged by dividing them into a central zone (c), both-side zones (e), and an intermediate zone (m), to control separately the density of flow rate at each zone. Flow controllers 6 control regulating valves 7 respectively so as to conform the flow rates obtained by flowmeters 4 to the set values of flow rates obtained by an arithmetic device 5 respectively. By this mechanism, the cooling water is sprayed on the upper-surface of sheet 1 by increasing its flow-rate density from the central part of sheet width to the end parts thereof within a range of 20%, to perform the cooling of sheet 1 without causing an irregularity of heat treatment and a cooling strain, then a hot rolled sheet having excellent quality and shape is obtained.</p> |
