External Sensor-Less Tool Contact Detection by Cutting Force Observer

Precise tool length measurement and work coordinate setup is technically a difficult operation which generally requires a manual adjustment and takes long time. Contact of cutting edge of a micro tool is conventionally detected by laser, vision sensor, acoustic emission sensor (AE sensor) and so on. However, those techniques are necessary to install additional sensors and equipments to a machine tool. In addition, tool setting technique depends on an engineer's skill. Therefore, skill-independent technology of tool setting is desired. In this study, we propose an automatic detection methodology of the tool contact by cutting force observer. Moreover, applying the developed detecting technique of the tool contact, automatic micro drilling system without tool setting is developed. Its validity is verified through glass micro drilling tests.