| 摘要 |
PURPOSE:To achieve high-sensitivity detection without using a high-frequency power source by providing an annular energizing coil which surrounds an induced current path and generates magnetic flux and a detection coil which surrounds the induced current path. CONSTITUTION:In a machine tool, for example, a troidal coil 20 surrounding a spindle 12 connects with an AC power source 21. When a tool T and a workpiece W come into contact with each other, an induced current flows through a current path 23 including the tool T, the spindle 12, a main shaft head 11, a brush 16, a working machine body 10, a table 15, and the workpiece W. Its induction magnetic field permits an alternating current to flow to a detection coil 22, which sends an AC voltage signal to a discriminating circuit 25. The energizing coil 20 and detection coil 22 are insulated magnetically by a shield part 24. Consequently, the contact between the tool T and the workpiece W is detected with high sensitivity without using a high-frequency power source. |
