Apparatus and method for ultrasonic detection to detect flaws of steel plate

1. An ultrasonic detection apparatus comprising:

an injection nozzle which is installed below a steel plate being transported and configured to form a medium column by jetting a medium toward the steel plate;

an ultrasonic probe which is installed in the injection nozzle and configured to transmit and receive ultrasonic waves for detecting flaws in the steel plate through the medium column;

a medium circulation unit which reclaims the medium falling from the medium column and circulates the reclaimed medium to the injection nozzle; and

a jet pressure control unit for supplying a jet pressure to the injection nozzle and controlling the jet pressure of the injection nozzle,

wherein the jet pressure control unit comprises:

a medium chamber for containing the medium which falls from the medium column and is reclaimed and supplying the contained medium again to the injection nozzle, and

a chamber height adjustor which is configured to adjust a height of the medium chamber to control the jet pressure of the injection nozzle.

2. The ultrasonic detection apparatus of claim 1 , wherein the medium circulation unit comprises:

a medium plate which is installed on an outer perimeter of the injection nozzle and configured to receive the medium which falls from the medium column;

a reclaiming pipe which is connected to the medium plate and configured to reclaim the medium in the medium plate; and

a supply pipe for supplying the medium in the reclaiming pipe to the injection nozzle.

3. The ultrasonic detection apparatus of claim 2 , wherein a filter for filtering the medium discharged from the medium plate is installed at the reclaiming pipe.

4. The ultrasonic detection apparatus of claim 2 , wherein the jet pressure control unit is installed between the supply pipe connected to the injection nozzle and the reclaiming pipe connected to the medium plate installed on the outer perimeter of the injection nozzle.

5. The ultrasonic detection apparatus of claim 1 , wherein the jet pressure control unit is a circulation pump.

6. The ultrasonic detection apparatus of claim 1 , wherein the jet pressure control unit comprises:

a medium chamber for containing the medium which falls from the medium column and is reclaimed and supplying the contained medium again to the injection nozzle; and

a surface level adjustor which is configured to adjust the surface level of the medium contained in the medium chamber to control the jet pressure of the injection nozzle.

7. The ultrasonic detection apparatus of claim 6 , wherein the surface level adjustor comprises:

a level sensor which is configured to sense the surface level of the medium contained in the medium chamber;

a first pipe for supplying the medium to the medium chamber;

a second pipe for discharging the medium from the medium chamber; and

a control unit which is connected to the first and second pipes and configured to control flow rates of the medium in the first and second pipes such that the surface level of the medium has a certain value based on a value sensed by the level sensor.

8. The ultrasonic detection apparatus of claim 7 , wherein the control unit comprises:

a supply chamber which is connected between the first and second pipes and contains the medium;

a supply pump installed at one of the first pipe and the second pipe;

first and second control valves installed at the first and second pipes, respectively; and

a controller which is configured to control the first and second control valves based on the value sensed by the level sensor.

9. The ultrasonic detection apparatus of claim 1 , wherein the chamber height adjustor comprises:

a driving portion which is configured to drive the medium chamber to move in the vertical direction; and

a controller which is configured to control an operation of the driving portion according to an input signal.

10. The ultrasonic detection apparatus of claim 1 , wherein a plurality of such ultrasonic probes are arranged in the width direction of the steel plate, and

wherein the injection nozzle is configured to accommodate a probe array formed by the plurality of ultrasonic probes.

11. The ultrasonic detection apparatus of claim 10 , wherein the probe array has a length that is greater than or equal to the width of the steel plate.