How is the thermometer used in hot rolling?
1. Basic principles
All objects with a temperature higher than zero are constantly emitting infrared radiation energy to the surrounding space. Infrared radiation characteristics of an object: the size of the radiation energy and its distribution according to the wavelength have a very close relationship with its surface temperature. Therefore, by measuring the infrared energy radiated by the object itself, its surface temperature can be accurately determined, which is the objective basis for infrared radiation temperature measurement.
Infrared thermometer, also known as infrared radiation temperature measurement, is a technology that uses the infrared radiation emitted by the object itself to measure the temperature of an object. Infrared radiation or infrared radiation is electromagnetic radiation with a wavelength between 0.76 μm and 1000 μm. For an ideal black body, the total radiation power of all wavelengths emitted per unit surface area to the hemispherical space (abbreviated as total radiation or radiation intensity) is 4 times the temperature of the object. Proportional to the power:
Mb(T) = σT4(1)
This is the Stephen-Boltzmann law. Among them, σ=5.6697×10-8W/m2K4 is called Stephen-Boltzmann constant.
Equation (1) is used for real objects and needs to be multiplied by the emissivity:
Mgb(T)=εσT4
It can be seen that the spontaneous emission intensity Mgb(T) of any object is related to the temperature of the object and the emissivity of the object. The emissivity ε of an object is directly related to its material properties (composition, metal and non-metal, crystal and amorphous, etc.), surface state (smooth and rough surface, degree of oxidation, pollution or surface coating, etc.) and the temperature of the object. As long as the emissivity of the object can be selected correctly, the actual temperature of the measured object can be accurately obtained.
Infrared thermometer is composed of three parts: optical system, detection unit and signal processing. The main function of the optical system is to collect the radiation power of the measured target and make it converge on the infrared detector. The function of the infrared detector is to convert the received infrared radiation into electrical signal output.
