Method and system for determining a series of temperature values of a molten metal bath

1 . A method for determining a series of at least two temperature values T mes (n) and T mes (n+1) of a molten metal bath with a device comprising an optical cored wire and a detector, wherein a leading tip of the optical cored wire is immersed under the surface of the molten metal bath at a point in time a temperature of the molten metal bath is obtained, the method comprising:

(a) supplying a model F(t) describing the temperature development of the molten metal bath with time;

(b) defining a critical temperature value T cri ;

(c) measuring a measured temperature value T mes (n) of the molten metal bath at a point in time t(n);

(d) determining a fitted heating rate R heat (n) based on the model F(t), the critical temperature value T cri and the measured temperature value T mes (n), wherein R heat (n) is defined as:

R heat ( n )=Δ T heat ( n )/Δ t;

(e) calculating a point in time t cal (n+1) based on the temperature difference ΔT(n) between the critical temperature value T cri and the measured temperature value T mes (n) and the fitted heating rate R heat (n), wherein:

Δ T ( n )= T cri −T mes ( n ); and, t cal ( n+ 1)= t ( n )+(Δ T ( n )/ R heat ( n )); and

(f) measuring a measured temperature value T mes (n+1) of the molten metal bath at the point in time t cal (n+1).

2 . The method according to claim 1 , wherein the method further comprises:

(g) determining a fitted heating rate R heat (n+1) based on the model F(t), the critical temperature value T cri and the measured temperature value T mes (n+1), wherein R heat (n+1) is defined as:

R heat ( n+ 1)=Δ T heat ( n )( n+ 1)/Δ t;

(h) calculating a point in time t cal (n+2) based on the temperature difference ΔT(n) between the critical temperature value T cri and the measured temperature value T mes (n) and the fitted heating rate R heat (n), wherein:

Δ T ( n+ 1)= T cri −T mes ( n+ 1); and

t cal ( n+ 2)= t ( n+ 1)+(Δ T ( n+ 1)/ R heat ( n+ 1)); and

(i) measuring a measured temperature value T mes (n+2) of the molten metal bath at the point in time t cal (n+2).

3 . The method according to claim 2 , wherein the fitted heating rate R heat (n+1) is higher than the fitted heating rate R heat (n).

4 . The method according to claim 1 , wherein the model F(t) describes the maximum temperatures for the development of the temperature of the molten metal bath with time.

5 . The method according to claim 1 , wherein the first derivative of the model F(t) describing the temperature development of the molten metal bath with time is a linear function.

6 . The method according to claim 1 , wherein the model F(t) describing the temperature development of the molten metal bath with time is based on previous measurements.

7 . The method according to claim 1 , wherein the model F(t) describing the temperature development of the molten metal bath with time is based on operational parameters.

8 . The method according to claim 1 , wherein the fitted heating rate R heat (n) is determined based on a linear fit of the model F(t).

9 . The method according to claim 1 , wherein the fitted heating rate R heat (n) is determined based on the first derivatives of the model F(t) for the point in time tori and the point in time t(n).

10 . The method according to claim 1 , wherein the model F(t) describing the temperature development of the molten metal bath with time is derived by a method comprising the steps of:

(i) providing a set of data relating characteristics of a molten metal bath with recorded data for the development of the temperature of a molten metal bath with time;

(ii) providing characteristics of the molten metal bath; and,

(iii) receiving a model F(t) describing the temperature development of the molten metal bath with time from the provided set of data relating characteristics of the molten metal bath corresponding to the provided characteristics of the molten metal bath.

11 . The method according to claim 1 , wherein a measured temperature value T mes is determined by the application of a measurement profile MP, the measurement profile MP comprising at least one of the following steps to obtain the temperature of the molten metal bath:

(i) providing the optical cored wire with its leading tip above the surface of the molten metal bath;

(ii) feeding the leading tip of the optical cored wire for a time period from t0 to t2 with at least one feeding velocity V fed towards the molten metal bath and below the surface of the molten metal bath, wherein the leading tip of the optical cored wire is below the surface of the molten metal bath during a time period from t1 to t2;

(iii) obtaining temperature information within a measuring time period within t1 to t2; and

(iv) retracting the optical cored wire with a velocity v ret to a position above the molten metal bath.

12 . The method according to claim 11 , wherein the measurement profile MP further defines a step within a stationary time period within t1 to t2, during which the feeding of the leading tip of the optical cored wire is paused with or the leading tip of the optical cored wire is fed with a low speed.

13 . The method according to claim 11 , wherein the feeding of step (ii) is defined by at least two feeding velocities v fed 1 and v fed 2.

14 . A system for determining a series of at least two temperature values T mes (n) and T mes (n+1) of a molten metal bath comprising a device and a module and the module is adapted to interact with the device,

wherein the device comprises an optical cored wire and a detector, the system configured to immerse a leading tip of the optical cored wire under the surface of the molten metal bath at a point in time a temperature of the molten metal bath is to be obtained,

wherein the module comprises a storage unit, a processing unit and a controlling unit,

wherein the storage unit comprises:

(a1) a storage element for supplying a model F(t) describing the temperature development of the molten metal bath with time;

(a2) a storage element for defining a critical temperature value T cri , wherein the processing unit comprises:

(b1) a processing element for determining a fitted heating rate R heat based on a model F(t), a critical temperature value T cri and a measured temperature value T mes , wherein R heat is defined as:

R heat =ΔT heat /Δt;

(b2) a processing element for calculating a point in time t cal based on a temperature difference ΔT between a critical temperature value T cri and a measured temperature value T mes and a fitted heating rate R heat , wherein:

Δ T=T cri −T mes and t cal =t +(Δ T/R heat ); and,

wherein the controlling unit comprises:

(c1) a controlling element for measuring a temperature value T mes of the molten metal bath.

15 . The system of claim 14 , wherein the optical cored wire has a linear density in a range of from 35 to 70 g/m.