Recently, the demand for realizing micromachining through small-diameter tools has increased. When performing microfabrication using a numerically controlled machine tool, a machining error may be introduced if the relative position of the tool tip and workpiece surface deviates during tool change. Therefore, it is critical to determine this relative position in an actual machining condition at a specific spindle speed. We are currently developing an air bearing turbine spindle with a built-in acoustic emission sensor that can detect the contact of the tool tip with the workpiece surface in real time. The acoustic emission (AE) signal generated at the tool tip can be accurately detected by placing the AE sensor in direct contact with the tool end surface inside the main shaft floated by air. In this study, we investigated the possibility of contact detection between the tool tip and the workpiece surface at the submicrometer level through the proposed spindle. The results of the performed evaluation experiments indicated that by using the spindle with a built-in acoustic emission sensor, the contact of the small-diameter tool tip with the workpiece surface could be detected with damage to the workpiece at the submicrometer level on average.

近来，通过小直径工具实现微加工的需求增加了。当使用数控机床进行微细加工时，如果换刀时刀尖和工件表面的相对位置发生偏离，可能会导致加工误差。因此，在特定的主轴转速下，在实际加工条件下确定该相对位置至关重要。我们目前正在开发一种带有内置声发射传感器的空气轴承涡轮机主轴，该传感器可以实时检测刀尖与工件表面的接触。通过将AE传感器与空气中漂浮的主轴内的工具端面直接接触，可以准确地检测出在工具尖端产生的声发射（AE）信号。在这个研究中，我们研究了通过建议的主轴在亚微米水平上检测刀尖与工件表面之间接触的可能性。进行的评估实验的结果表明，通过使用带有内置声发射传感器的主轴，可以检测到小直径刀尖与工件表面的接触，平均在亚微米级别上会损坏工件。