System and method for predicting failure in machine tool

A system for predicting an occurrence of failure in a machine tool comprising:

• a) first means for detecting a monitor data which is changed according to an operating situation in a series of working processes of the machine tool within an operating cycle, said first means including fifth means for detecting a load current of a servomotor installed in the machine tool as the monitor data, sixth means for detecting a position deviation variable of the servomotor, seventh means for detecting an orientation time of a main axle of the machine tool, and eighth means for detecting a speed arrival time at which the rotation of the main axle reaches a predetermined target speed;
• b) second means for variably setting a prediction level of failure against the monitor data, the prediction level being varied according to different types of operating situations in the machine tool within the operating cycle;
• c) third means for comparing the monitor data detected by the first means with the prediction level set by the second means during a predetermined one of the series of working processes of the machine tool, said predetermined one of the series of working processes including servomotor operation and main axle rotation, and outputting a failure prediction signal when the value of the monitor data exceeds the prediction level;
• and
• d) fourth means for informing the prediction of the occurrence of failure on the basis of the received failure prediction signal,
• wherein said machine tool is a Numerical Control machine tool which is operated in accordance with a predetermined working program and wherein said third means sets the predetermined working process as a comparison period of time during which the third means compares the monitor data with the prediction level on the basis of a time during which a predetermined command related to the servomotor operation and the main axle rotation in the working program of the Numerical Control machine tool has been processed.

A method for predicting an occurrence of failure in a machine tool, comprising the steps of:

• a) detecting at least one monitor data which is changed according to an operating situation in a series of working processes in the machine tool within an operating cycle, said at least one monitor data including a position deviation variable of a tool as a result of rotation of a servomotor installed in the machine tool;
• b) variably setting a prediction level of failure against the monitor data, the prediction level being varied according to different types of operating situations in the machine tool within the operating cycle;
• c) setting a comparison period of time according to the series of the working processes and comparing the monitor data detected in the step a) with the prediction level set in the step b) during a predetermined one of the series of working processes of the machine tool set as the comparison period of time, said predetermined one of the series of working processes including servomotor rotation;
• d) outputting a failure prediction signal when the value of the monitor data exceeds the prediction level;
• and
• e) informing the prediction of the occurrence of failure on the basis of the received failure prediction signal.

A method for predicting an occurrence of failure in a machine tool, comprising the steps of:

• a) detecting at least one monitor data which is changed according to an operating situation in a series of working processes in the machine tool within an operating cycle, said monitor data being a load current of a servomotor installed in the machine tool;
• b) variably setting a prediction level of failure against the monitor data, the prediction level being varied according to different types of operating situations in the machine tool within the operating cycle;
• c) setting a comparison period of time according to the series of the working processes and comparing the monitor data detected in the step a) with the prediction level set in the step b) during a predetermined one of the series of working processes of the machine tool set as the comparison period of time;
• d) outputting a failure prediction signal when the value of the monitor data exceeds the prediction level;
• and
• e) informing the prediction of the occurrence of failure on the basis of the received failure prediction signal.