| 摘要 |
PURPOSE:To detect the abnormality of cutting with high sensitivity, by separating a signal of thermoelectromotive force and a signal of electrical current across a cutting tool and a workpiece. CONSTITUTION:Both ends of a detection resistor R0 coupled in series between the table 2 of a machine tool and an AC power source E0 are connected to a differential amplifier 16. A low-pass filter 17 is coupled to the differential amplifier 16. Another low-pass filter 20 is coupled to the amplifier 16 through a band-pass filter 18 and a rectifier circuit 19. Voltage is applied across the table 2 and an electric contact 7 provided on the central part of the end of a main shaft 5. The magnitude of a circuit current is measured by the detection resistor R0. An AC voltage is applied across a cutting tool 4 and a workpiece 3. A signal of electrical current and a signal of thermoelectromotive force are separated from a signal detected from the detection resistor R0. It is judged from both former separated signals whether cutting is normal abnormal (wear, damage or the like of the cutting tool). Since the signal of electrical current and the signal of thermoelectromotive force show characteristic differences as to the normality and abnormality of the cutting, the purpose is attained. |
