Method and system for determining a temperature value of a molten metal bath

A method for determining a temperature value of a molten metal bath with a device comprising an optical cored wire and a detector, comprising:

• (a) providing the optical cored wire with its leading tip at a position pl above the surface of the molten metal bath;
• (b) feeding the leading tip directed towards the molten metal bath from position pl with a velocity v1 for a first time period from t1 to t2 to a position p2 in an immersion depth i1 below the surface of the molten metal bath;
• (c) feeding the leading tip with a velocity v2 for a second time period from t2 to t3 to a position p3 in an immersion depth i2 below the surface of the molten metal bath;
• (d) feeding the leading tip with a velocity v3 for a third time period from t3 to t4 to a position p4 in an immersion depth i3 below the surface of the molten metal bath;
• (e) either pausing with the feeding of the leading tip or feeding the leading tip with a velocity v4, each for a fourth time period from t4 to t5;
• (f) retracting the leading tip with a velocity v5 to a position above the surface of the molten metal bath after t5;
• and
• (g) obtaining temperature information of the molten metal bath within a measuring time period within t2 to t5, wherein the immersion depth and velocities have the following relations
• (i) i2>i1,
• (ii) i3>i2,
• (iii) v1>v2,
• (iv) v2<v3 and
• (v) v4<v1 or v2 or v3.