TOOL ABNORMALITY DETECTING DEVICE IN MACHINE TOOL

PURPOSE:To detect abnormality of a cutting tool with a high degree of accuracy to restrain a working process from being interrupted by an abnormal signal due to external noise, by detecting breakage of a cutting tool in accordance with an abnormal signal from an AE sensor and a breakage sensing output from a proximity switch. CONSTITUTION:Detection is made for breakage of a cutting tool only when an abnormal signal from an AE sensor 9 and a breakage sensing output from a proximity switch 14 are issued. Further, When no breakage sensing output from the proximity switch is issued even if an abnormal signal from the AE sensor 9 is issued, a confirming means 23 confirms that there is no breakage in the cutting tool. Thereafter, it is possible to detect whether the abnormal signal is caused by external noise or by abnormality such as, for example, breakage, chipping and abrasion, by checking whether the AE sensor 9 continues the issuance of the abnormal signal or not. Accordingly, it is possible to restrain a cutting process from being interrupted cue to external, noise so that the fabricating process may be carried out with a high degree of efficiency, thereby it is possible to avoid a failure in working due to breakage, chipping, abrasion or the like.