Development of a two-color pyrometer using a quartz optical fiber and an InGaAs－InAs composite device for cutting temperature measurement

The authors have previously developed a two-color pyrometer that combines a chalcogenide optical fiber with a photoelectric conversion element. Using this pyrometer, we established a technique for accurately measuring the highly small area temperature which changes rapidly—such as the cutting edge temperature of high-speed rotating micro-tools. However, chalcogenide optical fibers are difficult to obtain and have low mechanical strength for practical applications. In this study, we developed a new dual-element InGaAs–InAs sensor as a two-color detector. This new detector makes it possible to use a quartz optical fiber. Quartz optical fibers are much more readily available and have significantly higher strength. A newly developed InGaAs–InAs two-color pyrometer with a quartz optical fiber maintains key advantages such as fast response, the ability to measure temperatures in microscopic areas, reduced sensitivity to emissivity variations, high ability in high-temperature measurement and non-contact temperature measurement. The sensitivity characteristics of the developed pyrometer were theoretically analyzed and experimentally validated. Furthermore, the pyrometer was applied to measure cutting temperatures during turning operations of Ti-6Al-4V titanium alloy, S45C and 6000-series aluminum alloy. The validity and practicality of the temperature measurement system were then discussed based on these results.