| 摘要 |
PURPOSE:To prevent shearing force from reducing and the shear crack on the shearing surface from cracking by cooling a steel material gradually through the aperture of a damper and by the convection current according to the kind of steel and the temperature of steel material. CONSTITUTION:All the outer periphery of a cooling floor 1 is enclosed with a heat-insulating walls 15-18 and the temperature of the steel material 10 is measured on the inlet side and the outlet side of the cooling floor 1 enclosed with heat-insulating walls 15, 16. The amount of aperture of aperture parts 19, 20 formed by this measurement and the input from a temperature setting device 29 at the lower parts of the heat-insulating walls 15, 16 on the inlet side and the outlet side is controlled by opening or closing ventilating dampers 21, 22. Thereby, the temperature of the steel material is controlled by the inflow of air determined by the steel material 10 and its atmospheric temperature so that the temperature of the steel material 10 at a cold shearing time is not made too low. Consequently, the reduction of shearing force and shear crack on the shearing surface can be prevented from arising. |
