| 摘要 |
<p>In continuous casting of steel, the invention is able to accurately detect a crater end only from a value measured by a sensor without needing calibration based on the slab rivet method, etc. An ultrasonic shear wave sensor 6, 8 for transmitting an ultrasonic shear wave to a cast product 1 and receiving it and an ultrasonic longitudinal wave sensor 7, 9 for transmitting an ultrasonic longitudinal wave to the cast product and receiving it are installed at the same position in a continuous casting machine or at two positions apart in a casting direction but at the same position in a transverse direction of the cast product. From variations of an ultrasonic signal received by the ultrasonic shear wave sensor, it is detected that a crater end 4 of the cast product is matched with the installed position of the ultrasonic shear wave sensor. A calculation formula for determining the crater end from a propagation time of an ultrasonic longitudinal wave signal is calibrated such that the crater end computed from the propagation time of the ultrasonic longitudinal wave signal at that time is matched with the installed position of the ultrasonic shear wave sensor. After the calibration, the crater end is determined from the propagation time of the ultrasonic longitudinal wave signal based on the calibrated calculation formula.</p> |
