Modeling radiation pyrometry of glass during the container-forming process

Abstract

During the forming of glass containers by a variety of different processes, it is important to be able to accurately measure the temperature of the glass. Also, to be practical for production applications, the temperature-measuring technique must not interfere with the process or disturb the product. Radiation pyrometry is ideally suited for such demanding requirements. Narrow-band radiation pyrometers are non-contacting sensors that (depending on the operating wavelength) either measure the surface temperature or some weighted average of the surface and internal temperatures of semi-transparent glass objects without significantly affecting the product or its heat exchange with the environment. When using a narrow-band infrared radiation pyrometer to measure glass temperature during the container-forming process, the effects of glass color and thickness, pyrometer-operating wavelength and emissivity setting, and background conditions must be considered when interpreting the results. A mathematical model is used to investigate the relative errors that these effects introduce into the measured temperature results, and techniques for controlling and/or compensating for them are suggested.