Method for measuring temperature field in laser welding process

Abstract

The invention belongs to the technical field of measurement and relates to a method for measuring a temperature field in a laser welding process. In the laser welding process, a fusion line of a welding joint section and a represented temperature value (a material melting point temperature value) during metal welding are utilized, so that a method for measuring the temperature field in the laser welding process is designed, the thermal imagery and temperature field obtained by utilizing the conventional thermal infrared imager and software processing system thereof are accurately calibrated, and the important problems that the result of the temperature field obtained by the conventional thermal infrared image system has a large error compared with the actual result and an accurate calibration is absent because of the influence of essential factors such as metal steam / plasma radiation, fast temperature change and the like during the current laser welding are solved. The obstacle in the process of measuring the laser welding temperature field by utilizing the thermal infrared imager at present is offset, and a way is provided for accurately measuring the temperature field distribution of a fusion zone and a thermal influence area in the laser welding process.

Description

technical field [0001] The invention belongs to the technical field of measurement, and relates to a method for measuring a temperature field in a laser welding process. Background technique [0002] Due to the fast heat propagation speed in metal materials, the heat source density is highly concentrated during laser welding, so the temperature field during welding is very uneven, especially due to the existence of high-temperature metal vapor / plasma, liquid molten pool, solid heat-affected zone and In the solidification cooling area, even for the welding of the same material, the temperature difference in these areas is very large, such as the temperature of metal vapor / plasma can be as high as 8000 ° C, while the temperature of the solidification area may be several hundred degrees, and the melting point of the material to be welded There is a big difference, for example, the melting point of aluminum alloy is about 600°C, while that of titanium alloy is about 1700°C. The...

AI Technical Summary

Problems solved by technology

[0004] In the specific technical field of laser welding, the welding process will be accompanied by strong metal vapor / plasma radiation, and the temperature of metal vapor / plasma can reach above 8000°C. According to the law of black body radiation, these radiation bodies will be measured by infrared thermal imaging The wavelength band of the response produces a strong infrared radiation signal, which will enter the infrared thermal image, and the system cannot distinguish whether it comes from the measurement target surface or the infrared radiation energy from these gases, resulting in a large error in the measurement results

Therefore, although the infrared thermal imaging cameras currently used are all strictly calibrated, due to the factory calibration of the thermal imaging cameras, they are all carried out under a standard temperature source. In the temperature field measurement of the laser welding process, the current infrared The temperature field results obtained by the thermal image and its software processing system have a considerable error (sometimes as high as 500°C) from the actual temperature field, and all systems do not have calibration methods and practical calibration standards for this specific technology. Accurate correction of the obtained thermal image, resulting in the actual measured temperature field cannot be used in practice