| 摘要 |
PURPOSE:To improve reliability of prompt hole openability and cleanability of a molten steel by releasing the refractory plug inserted into the upper nozzle hole on a device for adjusting the flow rate of the molten steel together with a piston into the vessel by the pressure of high pressure gas. CONSTITUTION:A high pressure gas introducing port is punched in a moving plate 1-1 of a sliding nozzle 1 and a cylinder 6 and a refractory plug 7 are disposed in a stationary plate 1-2 and an upper nozzle 2 above said port. The vertical movement of a cylinder pipe 6-2 is restrained by plates 1-1, 1-2 engaged with the bottom flange of said pipe. When a high pressure gaseous source 8 is communicated with the introducing port prior to charging of the molten steel after receiving of the steel- secondary refining process, the pressure in the pipe 6-2 is hermetically closed by a seal and therefore the pressure rises sharply and the piston 6-1 is pressed onto the bottom surface of the plug 7 to transmit the cylinder thrust thereto. When the thrust attains the resistance of the plug 7, the plug 7 begins to float and the plug 7 and the piston 6-1 float acceleratively with a decrease in the resistance and are released into a pan 0. Since the gaseous pressure decreases sharply in this stage, the plate 1-1 is moved to an open position upon detection of said decrease to start charging the molten steel.
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