Development of Dynamic High-Speed True Temperature Measurement System for Welding Head Based on Infrared Radiation Thermometry

Temperature is an important basic parameter used to characterize the properties of objects, and is widely used in various fields such as metal processing, production life, aerospace, etc. The accuracy of temperature measurement has a crucial impact on each industry. With the continuous miniaturization of the size of electronic devices and the popularity and development of various wearable smart devices, miniaturization has become an important technical indicator of the level of technology of electronic components, so electronic components have also been developing in the direction of small size and high integration, and its welding temperature fluctuations caused by the product yield is also decreasing. Therefore, achieving real-time access to the solder head temperature during welding electronic components has become an urgent research topic for many related companies. Based on the working characteristics of transistorized welding power supply, this paper starts by analyzing the structural characteristics of the solder head, using the infrared spectral radiation characteristics of the solder head, and designs a laser-targeted optical system to measure the temperature of the solder head using the Lambertian method, to obtain the real-time true temperature of the solder head when working. The whole temperature measurement system consists of a hardware system part and a software system part. Among them, the hardware system includes the design of the optical system, I/V conversion and amplification circuit and the high-speed data acquisition system of the upper computer. The software part of the system mainly includes the design of the interface of the upper computer system. The software of the upper computer adopts LabVIEW for program design, which mainly includes the configuration and driving of AD acquisition card, data filtering, zero point measurement, temperature calibration, temperature calculation, real-time temperature curve and data storage. After the system was established and the software was debugged, the temperature measurement system was calibrated using a standard cavity blackbody furnace. First, the emissivity of the weld head during operation was tested using the integral blackbody method, and the results showed that the emissivity was in general agreement with literature data in both oxidized and non-oxidized states. Then, using this emissivity value, the cavity blackbody emissivity was calculated for the small holes in the solder head. Finally, system stability and repeatability experiments were performed using a constant-current transistorized welding power source. The uncertainty analysis of the method yielded an overall uncertainty of the method within 3%. By calibrating and configuring the temperature measurement system, the system can also be applied to other scenarios where high-speed accurate temperature measurement is required.