JP2642122B

PURPOSE:To detect with high precision the abnormality of a machine tool by supplying to a surveillance system a plurality of processing loads and cutting times having the quality of ambiguity. CONSTITUTION:A detection means 30 to detect the processing load of a machine tool and a detection means 17 to detect the time of cutting are provided. A membership function 11 showing the degree of an abnormal load in opposition to the size of a processing load detected by means of this detection means 30, a membership function 15 showing the degree of a tool life and a membership function 18 showing the degree of the tool life from the cutting time, are provided. In addition, a function 13 showing the degree of the abnormal load and a tool abnormality and a function 20 showing the degree of the tool abnormality from the degree of 2 tool lives, are had, and inputs (processing load, cutting time) having a plurality of qualities of ambiguity are joined by seeking the more sure degree MAR of tool abnormality from the degrees AR1, AR2 of abnormality of respective tools, and the more sure processing abnormality or tool abnormality is detected. That is to say, an alarm signal AN is outputted.