Device and method for measuring surface temperature of cast piece

1. A cast piece surface temperature measuring device comprising:

a magnetic field exciting device which applies an AC magnetic field substantially perpendicular to a surface of a cast piece;

a magnetic field detecting device which detects the AC magnetic field to detect a magnetic flux varied in response to a surface temperature of the cast piece; and

a surface temperature deriving device which derives the surface temperature of the cast piece based on an induced electromotive force obtained by detecting the AC magnetic field by the magnetic field detecting device and a predetermined relation data,

wherein the magnetic field exciting device includes a solenoidal excitation coil,

wherein the magnetic field detecting device includes a solenoidal detection coil interposed between the surface of the cast piece and the excitation coil,

wherein the relation data indicates a correspondence relationship between the surface temperature of the cast piece and the induced electromotive force in a temperature range including a predetermined Curie point,

wherein the cast piece is a slab obtained through a continuous casting by drawing the slab from a bottom of a mold, and

wherein the magnetic field exciting device and the magnetic field detecting device are arranged in a narrow side of the cast piece immediately under the mold and below a cooling zone to cool the narrow side of the cast piece.

2. The cast piece surface temperature measuring device according to claim 1 , wherein the relation data is an equation which indicates the correspondence relationship between the surface temperature of the cast piece and the induced electromotive force.

3. The cast piece surface temperature measuring device according to claim 1 , wherein an application frequency of the magnetic field excited by the magnetic field exciting device is equal to or more than 0.5 Hz and equal to or less than 20 Hz.

4. A cast piece surface temperature measuring method which measures a surface temperature of a cast piece using the cast piece surface temperature measuring device according to claim 1 , the method comprising:

applying the AC magnetic field to the cast piece by the magnetic field exciting device and detecting the AC magnetic field by the magnetic field detecting device; and

deriving the surface temperature of the cast piece by the surface temperature deriving device.

5. The cast piece surface temperature measuring device according to claim 1 , wherein the magnetic field exciting device and magnetic field detecting device are aligned with a center of the narrow side of the cast piece.

6. The cast piece surface temperature measuring device according to claim 1 , further comprising:

a glass epoxy-based pipe,

wherein the solenoidal excitation coil and the solenoidal detection coil are wrapped around the glass epoxy-based pipe.

7. The cast piece surface temperature measuring device according to claim 1 , further comprising:

an oscillator; and

a constant current amplifier connected the oscillator, the constant current amplifier providing power to the solenoidal excitation coil.

8. The cast piece surface temperature measuring device according to claim 1 , wherein the solenoidal excitation coil and solenoidal detection coil are a predetermined distance from the cast piece.