Detecting method of abnormality of machine tool operation

A detecting method of abnormality of a machine tool operation, which detects chucking miss of a material, wear and damage of a tool or the like, comprising:

• a preparing step S100 of setting a kind of tool and a machining process at a host computer in a state that a current sensor and a voltage sensor are installed at a power line of a motor drive unit of the machine tool and connected to a sensor processor, and the sensor processor is connected to a monitoring controller, and the monitoring controller is connected to the host computer and a machine tool controller;
• a reference waveform obtaining step S200 of measuring a drive voltage and a drive current using the current sensor and the voltage sensor, while machining the material in a normal state of the machine tool, and obtaining a reference waveform which functions as a standard for determining abnormality of the tool;
• a monitoring section setting step S300 of setting a monitoring section with respect to the reference waveform obtained in the reference waveform obtaining step S200 and thus automatically calculating a maximum load value and a minimum load value;
• a permissible limit setting step S400 of setting maximum and minimum permissible limits in order to set an alarm operation section based on the maximum and minimum load values calculated in the monitoring section setting step S300;
• and
• a monitoring step S500 of continuously obtaining a machining load generated when actually machining the material and determining whether a difference between maximum and minimum load values of the machining load obtained in the monitoring section is out of the maximum or minimum permissive limit and then outputting normality or abnormality thereof.