Apparatus for preventing damage to casting rolls in strip casting machine

1. An apparatus for preventing damage to casting rolls in a strip casting process in which the casting rolls are driven according to a target pressure value for maintaining a set roll gap, the apparatus comprising:

a roll pressing force detection unit measuring a roll pressing force applied to the casting rolls;

a foreign object determination unit determining whether foreign objects have been introduced to the casting rolls based on the measured roll pressing force;

a roll gap instruction value generation unit generating a roll gap instruction value by adding a preset roll gap amount to the set roll gap if it is determined that foreign objects have been introduced to the casting rolls; and

a roll gap control unit controlling a roll gap between the casting rolls based on the roll gap instruction value.

2. The apparatus of claim 1 , wherein the roll gap control unit controls the roll gap between the casting rolls based on the roll gap instruction value for a preset period of time, and

after the preset period of time, the roll gap control unit controls the roll gap between the casting rolls based the set roll gap.

3. The apparatus of claim 1 , wherein the preset roll gap amount is proportional to the measured roll pressing force.

4. The apparatus of claim 2 , wherein the preset period of time is several seconds or shorter.

5. The apparatus of claim 1 , further comprising:

a roll gap detection unit measuring a roll gap between a driving roll and a fixed roll constituting the casting rolls;

a roll gap deviation calculation unit calculating a roll gap deviation along axes of the driving roll and the fixed roll based on the measured roll gap;

a low pass filter unit through which the roll gap deviation is low-pass-filtered; and

a pair of casting roll cylinders controlling the roll gap deviation according to a new target pressure value obtained by adjusting the target pressure value using the low-pass-filtered roll gap deviation.

6. The apparatus of claim 5 , wherein the pair of casting roll cylinders comprise:

a first casting roll cylinder disposed on one side of the axis of the driving roll so as to drive the driving roll; and

a second cast roll cylinder disposed on the other side of on the axis of the driving roll so as to drive the driving roll.

7. The apparatus of claim 6 , wherein a target pressure value is increased for a casting roll cylinder disposed on one side of the axis of the driving roll to which foreign objects are introduced, and a target pressure value is decreased for a casting roll cylinder disposed on one side of the axis of the driving roll to which foreign objects are not introduced.

8. The apparatus of claim 6 , wherein one of the pair of casting roll cylinders drives the driving roll according to a new target pressure value obtained by adding a value based on the low-pass-filtered roll gap deviation to the target pressure value, and

the other of the pair of casting roll cylinders drives the driving roll according to a new target pressure value obtained by subtracting a value based on the low-pass-filtered roll gap deviation from the target pressure value.

9. The apparatus of claim 8 , wherein the value based on the low-pass-filtered roll gap deviation is a value obtained by multiplying the low-pass-filtered roll gap deviation by a constant.

10. The apparatus of claim 6 , wherein the roll gap deviation is a value obtained by subtracting a roll gap between the driving roll and the fixed roll measured on the side on which the second casting roll cylinder is disposed from a roll gap between the driving roll and the fixed roll measured on the side on which the first casting roll cylinder is disposed.

11. The apparatus of claim 5 , wherein the pair of casting roll cylinders start to operate when molten steel solidified on a leader strip is drawn out between the casting rolls.