In-process monitoring of tool temperature in end milling by newly developed compact two-color pyrometer

A compact two-color pyrometer using an optical fiber is developed for the purpose of monitoring the tool temperature in end milling. The infrared rays radiated from the cutting tool are accepted by a chalcogenide glass fiber and led to the laminated-type InAs/InSb two-color detector. The detector is thermoelectrically cooled at -60 degrees C without liquid nitrogen by Peltier device. Therefore the sensor is miniaturized and is easy to handle and mountable to the machine tool. This pyrometer has a good signal-to-noise ratio and large measurable range above approximately 200 degrees C. In addition, it has a flat response up to approximately 100 kHz, which is enough speed to measure the temperature of a cutting tool in high speed end milling. The temperature of carbide tool during intermittent cutting of carbon steel is measured with this pyrometer developed. The tool wear is also judged by tool temperature.