| Summary: | 碩士 === 國立中正大學 === 機械工程學系暨研究所 === 101 === There are two purposes of this research. Firstly, a technique based on the method of Angular Velocity Vold-Kalman Filtering Order Tracking (AV VKF-OT) for monitoring the occurrence of preload loss of a ball screw in a feed drive system is proposed. Secondly, a method to measuring the ball screw friction torque induced by the preload is introduced. In detecting the preload loss in a ball screw feed drive system, it is worthy of noting that both the ball pass order and the vibration amplitude change corresponding to the major ball pass order along the screw shaft are monitored. It shows that the vibration amplitude of the ball screw without preload is not only higher than those with preloads but also varies strongly when the nut is traveling along the ball screw shaft. It also shows that the vibration amplitude variation along the shaft without preload is much larger than those with preload. Taking not only the change of BPO but also the vibration amplitude variation as well into account, experimental results show that the accuracy in detecting the occurrence of preload loss can be improved up to 93% approximately. On the other hand, the ball pass order changes little as the temperature rises from 25.5℃to 36.3℃. It concludes that the preload appears to be unaffected in this temperature range. For measuring the ball screw friction torque induced by the preload, a platform that consists of loadcells and accelerometers is introduced. The torque measured using this platform does not include the friction torque from bearings and thus it reflects the torque induced only by the preload on the ball screw.. Experiment results show that the torque induced by ball screw preload is 71% to 80% of that measured using the traditional torque sensor. That is, for a ball screw feed drive system, the ball screw preload costs 71-80% of the torque from motor, whereas the bearing accounts for the remaining 20-30%.
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