A New Method for Temperature Measurement of Wire Rod Based on Adaptive Exposure Time

In wire rod production, the temperature change range of different wire rods is large. However, the thermal imagers usually suffer from the problem of low-temperature resolution when dealing with such a wide temperature measurement range, which greatly affects the temperature measurement accuracy. To address this issue, we propose an adaptive exposure time setting method tailored to individual wire rods based on the temperature characteristics of the measured objects (i.e., relatively small temperature differences within the same rod). When a wire rod enters the thermal imaging camera’s field of view, the maximum temperature is measured within a short period. Subsequently, the appropriate exposure time and calibration curve for the corresponding temperature range are determined. Compared to the fixed exposure time approach, this method substantially enhances the temperature measurement resolution. For instance, at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$500~^{\circ }$ </tex-math></inline-formula>C–<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$710~^{\circ }$ </tex-math></inline-formula>C, the average resolution improves from 0.12 to 9.86 DN/°C, and at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$910~^{\circ }$ </tex-math></inline-formula>C–<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$970~^{\circ }$ </tex-math></inline-formula>C, it rises from 2.33 to 17.57 DN/°C, thereby enhancing measurement accuracy. Finally, application tests demonstrate that this method significantly improves the thermal image quality of wire rods at different temperatures, potentially offering a new approach for improving the temperature measurement accuracy of objects with a wide temperature dynamic range.