ACCEPTED
Please predict whether this patent is acceptable.PATENT ABSTRACT: A machine learning unit capable of judging the necessity of replacement of a spindle of a machine tool. A machine learning unit includes a state observing section observing a state variable comprising processing volume data showing a number of processed workpieces, processing accuracy data showing a difference between an actual dimension of a processed workpiece and a dimension target value, interruption time data showing a time period of interruption of operation of the machine tool, and replacement determination data showing a judgment result of a necessity of spindle replacement; and a learning section provided with profit-and-loss data comprising a profit per unit time or a loss per unit time, generated by a production of the processed workpiece, and a loss per unit time generated due to the spindle replacement. The learning section uses the profit-and-loss data and the state variable and learns a condition associated with the spindle replacement.