A method for detecting a drop in preload of a ball screw and a direct-acting drive device

摘要

A method for detecting a decrease in a preload applied to a ball screw, and a direct drive drive device including a ball screw capable of detecting a decrease in the preload are provided. The linear drive device includes a ball screw (9), a linear motion table (1) driven by the ball screw (9) to move linearly, and an abnormality detection device (11) for detecting a decrease in the preload applied to the ball screw (9). ) is provided. The abnormality detection device 11 acquires the vibration value of the vibration signal in a specific frequency band among the vibration sensor 10 that measures the vibration when the ball screw 9 is operated, and the vibration signal measured by the vibration sensor 10 . Calculation processing unit 12 and the vibration value during the initial and normal operation of the ball screw 9 as a reference value, when the vibration value is less than a predetermined threshold value with respect to this reference value, the ball screw 9 is It has an abnormality detection part 13 which judges that the fall of the preload has occurred.