Abstract
Automating machining processes require the functions of high-accurate process monitoring. However, additional sensors have problem that they lead to high-cost and reduce stiffness and reliability of mechanical systems. Authors proposed system called cutting force observer, which is the sensor-less and real-time cutting force estimation methodology based on the disturbance observer theory. There are possibilities that monitoring methods using the cutting force observer enhance the productivity in turning. One of the parameter which significantly-affects the cutting process is shear angle. Determining the shear angle is very important that it can be used to know the machining condition. In this study, external sensor-less monitoring system of shear angle in turning is developed and its performance is evaluated.