How is infrared thermometer used in hot rolling?
1. Basic principles
All objects with a temperature higher than **zero are constantly emitting infrared radiation energy into the surrounding space. Infrared radiation characteristics of an object: The size of the radiation energy and its distribution by wavelength are closely related to its surface temperature. Therefore, by measuring the infrared energy radiated by the object itself, its surface temperature can be accurately measured. This is the objective basis on which infrared radiation temperature measurement is based.
Infrared thermometer, also known as infrared radiation temperature measurement, is a technology that uses infrared radiation emitted by the object itself to measure the temperature of an object. Infrared radiation, or infrared rays, 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 to the hemispheric space per unit surface area (referred to as total radiance or radiation intensity) is 4 times the temperature of the object. Proportional to the power of:
Mb(T)=σT4(1)
This is the Stefan-Boltzmann law. Among them, σ=5.6697×10-8W/m2K4 is called Stephen-Boltzmann constant.
Equation (1) is used for actual objects and needs to be multiplied by the radiation rate:
Mgb(T)=εσT4
It can be seen that the spontaneous radiation 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 the properties of its material (composition, metal and non-metal, crystal and amorphous, etc.), surface state (surface smoothness and roughness, degree of oxidation, pollution or surface coating, etc.) and the temperature of the object. As long as the emissivity of the object is chosen 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 focus it on the infrared detector. The function of the infrared detector is to convert the received infrared radiation into electrical signal output.
