| 摘要 |
PURPOSE:To instantaneously stop cutting and perform spot facing of a mark, by detecting cutting resistance, delicately changed in accordance with a material changing from a non-conductive material layer to copper foil in an inner layer circuit of a work to be cut, as a fine change of electric power in a motor rotating a tool to be driven. CONSTITUTION:A cutting tool 1, if it is lowered while rotating, adapts its edge point first to outer layer copper foil 2, and cutting resistance at this time is assumed to be, for instance, 100. The tool advances spot facing being adapted to a non-conductive material layer 4, and cutting resistance at this time is assumed to be, for instance, 80. The edge point, further advancing, is adapted to an inner layer circuit 4, obtaining cutting resistance again 100. This change of cutting resistance causes a load current to change in a rotary driving motor, and a device, detecting this change of the load current by a converter 18, input device 19, fine current detector 9 and a rotation control device 10 so as to stop the tool 1 lowering instantaneously when a load changes in the cutting resistance 100 80 100, discloses properly a reference position display mark 5 on the inner layer circuit 4. |
