| 摘要 |
PURPOSE:To eliminate misdecision due to noise caused by mechanical vibrations, collision of chips, flying of cutting oil and the like and malfunctioning due to frictions between tools and work along with a simplified circuitry by outputting a tool abnormality signal detecting a frequency ratio rise abnormality signal. CONSTITUTION:An output signal of a frequency ratio Y/X from a divider 7 is inputted into a second comparator 11 provided in a bypass separated from a comparator 9 and a frequency ratio abnormality signal is inputted into an AND circuit 12 when the level of the frequency ratio Y/X exceeds the set threshold A. The abnormality signal of the frequency ratio Y/X is inputted into the AND circuit 12 as outputted when the variation rate of the frequency ratio Y/X exceeds the set threshold B in the comparator 9. When both of the signals are generated simultaneously, a tool abnormality signal is outputted to an output circuit 10. Thus, depending on such two signals, the abnormality of the tool can be detected accurately. |
