| 摘要 |
PURPOSE:To detect the rate of erosion of a gas blowing nozzle at furnace bottom easily and surely from the rate of erosion of artificial flaws by making ultrasonic waves incident to a fine metallic bar which is inserted into the longitudinal direction of said nozzle and is provided with >=1 point of artificial flaws from one end thereof on the nozzle outside and measuring the ultrasonic waves reflected from the artificial flaws. CONSTITUTION:When molten steel is blown by blowing a gas therein through a piping 4 out through a nozzle 3, the nozzle 3 is eroded together with the bricks 2 in the furnace; at the same time, the erosion progresses at the preceding end of a fine metallic bar 6 inserted into the nozzle 3. Under such conditions, the ultrasonic waves made incident to the inside of the bar 6 are reflected from artificial flaws 9, 9' and an end face 10; therefore, the reflection echoes of the ultrasonic waves from the artificial flaws and the end part shown in the figure are obtained. Further, when the erosion of the nozzle 3 progresses and the flaw 9 is eroded, the reflection echo (a) from the flaw 9 is annihilated. When the reflection echo (b) of the flaw 9' is annihilated by the progression of the erosion of the nozzle, the result indicates that the bar is eroded up to the part 9'. In other words, the erosion of the nozzle is detected from the presence or absence of the reflected echoes of the ultrasonic waves. |
