| 摘要 |
PURPOSE:To surely detect the breakage of a cutting tool with time lag, by causing discharge between the cutting tool and a needle located near it and by judging whether normal discharge has taken place or not. CONSTITUTION:A drill 2 is attached to a spindle 1, which is moved up and down. A pressure foot 3 is provided around the drill 2. A needle 4 is attached to the pressure foot 3 so that the needle is insulated therefrom. A high voltage generator 5 is connected to the spindle 1 and the needle 4 through a detector 6. The sindle 2 is moved up and down to perform cutting work while the drill 2 is rotating. When the drill 2 has reached the top dead center, discharge is caused between the drill and the needle 4 by the high voltage generator 5 and the voltage change is found out by the detector 5 to judge normal discharge has taken place or not. According to this constitution, the breakage of the drill 2 can immediately be detected. |
