| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect abnormality of a ball screw when an end of a ball screw nut is firmly fixed to a table with mass of ten times or more of that of the ball screw nut.SOLUTION: A vibration sensor 10 attached to a ball screw nut 6 detects vibration, vibration data in a ball screw abnormality detection frequency band is filtered from the detected vibration data, and abnormality of a ball screw is detected on the basis of filtered vibration data in the ball screw abnormality detection frequency band. In that case, a frequency band equal to or below a fixed-free primary longitudinal natural frequency of the ball screw nut 6 is filtered as an abnormality detection frequency band of the ball screw 9. If an axial end of the ball screw nut 6 is firmly fixed to a linearly moving table 1 of high rigidity having mass of ten times or more of that of the ball screw nut 6, the ball screw nut system has support close to fixed-free support, and thus abnormality is detected from a change in a harmonic component in a frequency band equal to or below the fixed-free primary natural frequency of the ball screw nut 6. |
