Abstract
On-machine measurement (OMM) is introducing to Numerical Control (NC) machine tools. By the OMM, a workpiece is measured on the machine tool (i.e., without loading and unloading), so OMM can reduce the setup time and positioning error for reloading a workpiece. OMM is used for the process control during machining because it is still difficult to suppress the machining error caused by the cutting process such as the tool deflection, the tool wear and the heat deformation during machining. There are several approaches to on-machine measurement, including non-contact measurements using a laser displacement sensor or imaging equipment and contact measurements using a touch probe. However, to conduct OMM with a touch probe it is necessary to generate an NC program by operators. Moreover, for the process control and monitoring, the information of machining process should be considered in the measuring plan.
For process control, measurement of a region that affects machining in the next process should be conducted during the machining process (i.e., after the machining of that region). Furthermore, when some machining abnormality that affects product quality occurs during the machining process, the abnormality should be detected and measured at an early stage to avoid unnecessary machining.
This study aims to realize the automation of planning for on-machine measurement, where measurement is conducted at the necessary time during the machining process based on process planning for the early detection of machining abnormality. Furthermore, when a machining abnormality is detected based on the measurement results, the proposed system automatically judges whether to stop machining or to re-machine the affected region.
