| Summary: | 碩士 === 國立高雄應用科技大學 === 機械與精密工程研究所 === 103 === In this paper, an ultrasonic motor operating in two shear vibration modes is proposed. The stator of the motor is formed by obliquely placing four piezoelectric actuators in a four-side hollowed cubic elastic body. The two orthogonal vibration modes are driven by the sine voltage with phase difference between the two sets of piezoelectric actuators. Then, the stator has elliptical trajectory deformation at the hole edge around the z-direction. The object is driven by friction force due to the deformation happened in the hole edge. Based on the operating principle, two types of ultrasonic motor were designed in this study.
In a design of rotary ultrasonic motor, it consists of stator, rotor, bearing, preload spring, and screw nut. The rotor is pushed by friction force due to the deformation happened in the hole edge of the stator. To improve the performance of the motor, a preload force is adjusted by a preload spring. In the experiment, a motor prototype was fabricated according to the analyzed results for measurement. The measured speed of the rotor approached 69.77 rpm when applying 18 V peak voltage to the stator with loading force of 82.4 mN.
In a design of screw-driven ultrasonic motor, it consists of a stator and a screw rod. The hole was designed in the z-direction of the stator, exactly fitting the screw rod to be pushed. The stator is operated by driving the x and y shear vibration modes with phase difference. Then, the stator has elliptical trajectory at the threaded hole edge and drives the screw rod to rotate. In experiment, the translational speed of the screw-driven motor is 2.137 mm/s when applying 16 V peak voltage without mechanical load. The translational speed of the motor is 1.174 mm/s with 16 g mechanical load under 16 V peak voltage driving.
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