TOOL ABNORMALITY DETECTING DEVICE

PURPOSE:To permit to discriminate the abnormality of the tool correctly by a method wherein the device is constituted so as to be capable of catching the change of peak value in a load torque surely and deciding the condition of abrasion of the tool, in the tool abnormality detecting device on a rotary main spindle supported by a main spindle head through bearings. CONSTITUTION:The load torque, acting on the main spindle 12, is detected by a torque detecting means 16 and the output of the means 16 is inputted into a peak value detecting circuit 21. The output of the circuit 21 is synchronized with the rotation of the main spindle 12, or synchronized with the breaking of a pulse signal outputted by a pulse generating means 18 generating the pulse at every one rotation of the main spindle 12, for example, and is shifted to a sample holding circuit 22, thereafter, the circuit 21 is reset in synchronized with the building-up of the pulse signal. According to this method, a signal, indicating the change of the maximum peak generated in one turn of the main spindle, is outputted from the circuit 22 and when the output of the circuit 21 exceeds an allowable value with respect to the reference value, an abnormality signal is outputted.