Abstract: A monitoring device for a machine tool, which monitors operations in work machining to increase the precision level of the work yield. To monitor a load current supplied to a machining motor in 1-cycle units, sampling points are taken at shorter intervals along the time axis of the machining in areas where the machining is complex. In areas where the machining is simple sampling points are taken at longer intervals. At each sampling point the sampling data are stored and undergo numerical processing. The load current measured value is compared to determine whether the measured value is within a range of limits determined by a standard deviation value calculated from the sampling data at each sampling point. Determination as to defective/non-defective is performed at each sampling point on the basis of the range of limits which model the shape of the work.

Abstract: Disclosed is a monitoring device for a machine tool, which monitors operations in work machining to increase the precision level of the yield of the work. To monitor a load current supplied to a machining motor in 1-cycle units which run from the start of the machining to the end of the machining, sampling points are taken at shorter intervals along the time axis of the machining in areas where the machining is complex, and in areas where the machining is simple sampling points are taken at longer intervals along the time axis of the machining; and at each sampling point the sampling data are stored and undergo numerical processing. Then, the actually measured value of the load current is compared to determine whether or not the actually measured value is within a range of an upper and a lower limit which are determined by a standard deviation value calculated from the sampling data at each sampling point, to thereby monitor the machining process.