| 摘要 |
PURPOSE:To make it possible to detect conduction state without the need of working blade edge of a cutting tool and without deteriorating durability of the cutting tool, by providing an electric contact within the circular periphery of the blade edge except the center and the edge of the blade. CONSTITUTION:When a start switch 13 is pushed, a cutting tool 6 is lowered while it is rotated as a clamp is lowered. The blade edge of the cutting tool and an electric contact 8 is contacted with an outer copper foil layer 1a and, thereby, an electric conduction signal is produced. This signal is sent to a lowering/raising operation control section 12 via a slip ring 16 and added to a counter circuit in the control section 12. A lowering speed decreasing signal is produced by controlling a pulse motor by a control section 10. An insulating substrate 2a is counterbored and the blade edge and the electric contact are contacted with a reference position mark 4 on an inner copper foil layer 16. Thereby, a second conduction signal is added to the counter circuit. If a count reaches a value set by a layer setting switch 18, the cutting tool is stopped and raised by a motor control drive circuit. |
