Research on some influence factors in high temperature measurement of metal with thermal infrared imager

Thermal infrared imagers have been introduced into the research field of metal processing temperature in recent years, such as the workpiece's and the tool's temperatures in metal machining. However, these metal components are usually non-black body with unknown and varied surface emissivities, plus the in-line processing environment also effects the measurement of infrared imager. Hereby, accurately measuring metal processing temperature with infrared imager becomes a challenge. In this paper, the temperature measurement formula of infrared imager is analyzed first, and next the experimental devices designed by the authors is introduced, then several influences on the temperature measurement, such as low temperature and high temperature backgrounds with high emissivity, object area / viewing field ratio, and the shooting angel, are experimentally investigated with a thermal infrared imager. The results indicate that a low temperature background with high emissivity and a small object area / viewing field ratio, as well as a shooting direction perpendicular to the measured surface, can improve the measurement accuracy. This work provides a useful reference for the temperature measurement in metal processing.