Abnormality diagnostic device for feed axis mechanism

An abnormality diagnostic device for a feed axis mechanism diagnosing an abnormality occurrence and an abnormal portion of the feed axis mechanism, the feed axis mechanism transmitting a rotation of a motor to a ball screw coupled by a coupling to rotate the ball screw, the abnormality diagnostic device comprising:

• a resonance frequency measuring unit that measures a resonance frequency at a plurality of stroke positions within a stroke range of the feed axis mechanism;
• and
• a diagnosis unit that identifies the abnormal portion based on a relationship between the stroke positions and change amounts relative to a standard value of the measured respective resonance frequencies;
• and
• wherein when the change amount relative to the standard value of at least one of the resonance frequencies measured at two stroke positions exceeds a preset abnormality existence determination threshold, the diagnosis unit determines that there is an abnormality in the feed axis mechanism, and
• when the abnormally is determined to be in the feed axis mechanism, the diagnosis unit obtains a difference between the change amount relative to the standard value of the resonance frequency measured at the stroke position on a coupling joining side and the change amount relative to the standard value of the resonance frequency measured at the stroke position on a counter coupling joining side, and the diagnosis unit diagnoses the abnormality in the feed axis mechanism as an abnormality of the coupling when the difference exceeds a preset abnormal portion identification threshold, and diagnoses as the abnormality in the feed axis mechanism as an abnormality of the ball screw when the difference is less than or equal to the preset abnormal identification threshold.