| 摘要 |
PURPOSE:To enable the setting of optimum sensitivity even when the sensitivity does not settle within a variable range of AE sensor sensitivity for a fixed time, by making an acoustic emission (AE) sensor count at a frequency set for each sensitivity to set the sensitivity on the AE sensor based on the sensitivity corresponding to the maximum of counts thereof as optimum value. CONSTITUTION:A signal processing section 7 identifies the breakage of a tool 2 based on the output signal of an acoustic emission sensor 6. A pseudo breakage signal generator 4 generates a pseudo breakage signal containing frequency components of an AE signal obtained with the breaking of the tool 2 based on the level set. Then, a CPU 9 drives the generator 4 depending on a driving level corresponding to the tool used to set the amplification factor of a variable amplification factor amplifier at the signal processing section 7 to an optimum value making the AE sensor 6 count at the frequency set for each sensitivity. Thus, when the amplification factor is not set to the optimum value with the CPU 9 within a specified time, the sensitivity of the AE sensor 6 is set with a numerical controller 3 based on the sensitivity corresponding to the maximum value of counts as optimum value.
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